HISTOLOGY = the study of tissue
Chapter 4: The Tissue Level of Organization
HISTOLOGY is the microscopic study of tissue. These are many
techniques that can be used, the major ones including a biopsy
and/or an autopsy.
TISSUE: a group of cells that usually have a common
embryological origin and work together to carry out a specific
function. There will be communication between these cells that
allows them to function as a unit.
BIOPSY: The removal of tissue samples from patients (surgically
or through a needle) for diagnostic purposes.
AUTOPSY: Examination of the organs and tissues of a dead body to
determine cause of death. Microscopic examination of the removed
tissue is often part of the procedure.
TYPES OF TISSUES
Body tissues can be classified into 4 groups.
1. Epithelial tissue: covers surfaces, lines inside of organs
and body cavities and forms glands.
2. Connective tissue: protects and supports body, binds organs
together, provides immunity.
3. Muscle tissue: movement and generation of heat
4. Nervous tissue: initiate and transmits impulses (action
potentials) that control and coordinate the functioning of the
body.
These different tissue types are interdependent. For example,
when flexing the arm, the bones cant move without the skeletal
muscle contracting and this contraction cannot occur without the
nervous tissue carrying an impulse to those muscles.
The cells that compose a tissue are not just found near each
other. There may be physical connections that allow for
communication between them. These points of contact between the
plasma membranes of 2 cells are called GAP JUNCTIONS.
1. EPITHELIAL TISSUE (epithelium)
There are 2 general classifications of epithelium. The first is
COVERING and LINING EPITHELIUM and the second is GLANDULAR
EPITHELIUM. Covering and lining epithelium forms the outside layer
of the skin and the outside and inside layer of internal organs and
structures. Glandular epithelium makes up the secreting portion of
the glands.
GENERAL CHARACTERISTICS OF EPITHELIAL TISSUE:
1. Epithelial cells have an APICAL surface and a BASAL surface.
The apical surface is free and the basal surface is connected to a
BASEMENT MEMBRANE.
2. Epithelial cells are arranged close together in the
tissue.
3. Epithelial cells are arranged in sheets that are either
single or layered to form the tissue.
4. Many gap junctions occur in epithelial tissue.
5. Avascular tissue. No blood vessels found in epithelial
tissue. The cells rely on diffusion of O2 and nutrients from nearby
vessels.
6. Epithelial tissue has a nerve supply.
7. High rate of mitosis due to location causing wear and
tear.
8. FUNCTIONS: protection, filtration, lubrication, secretion,
absorption, and other functions.
COVERING AND LINING EPITHELIUM 1. Arrangement of layers: 2 main
possibilities = simple and stratified
a. SIMPLE EPITHELIUM: single layer of cells
b. STRATIFIED EPITHELIUM: 2 or more layers of epithelial cells.
Mostly found in areas of high wear and tear
2. Epithelial cell shapes = 3 possible shapes
a. SQUAMOUS Epithelium: flat cells (skin)
b. CUBOIDAL Epithelium: cube shaped cells (kidney tubules)
c. COLUMNAR Epithelium: shaped like columns. Some have cilia on
them (trachea)
When describing epithelium, usually 3 words are used: the cell
arrangement, cell shape, and word epithelium - Ex. Simple cuboidal
epithelium
In stratified tissue, there may be more than one cell shape in
the layers. To name, use the shape of the top layer of cells. An
example is stratified squamous epithelium, where the cell shape of
the top layer of cells is flat (squamous shaped).GLANDULAR
EPITHELIUM:
The function of glandular epithelium is secretion. A GLAND may
consist of a cluster of epithelial cells or just one epithelial
cell that is capable of producing a secretion.
There are 2 types of glands: Exocrine and Endocrine glands.
a. Endocrine glands: These are DUCTLESS glands - secretions do
not go through a duct. These secretions are called HORMONES.
Example: Pituitary gland.b. Exocrine glands: glands in which the
secretions that are produced flow onto through a tube-like
passageway (a DUCT) to get to the surface or the lumen surface of
the organ. Example: Mucus and digestive glands.
2. CONNECTIVE TISSUE:
This is the most abundant type of tissue in the body. There are
a variety of different tissues in this group.
Examples include bone, cartilage, blood, and adipose. Many
times, the cells of this type of tissue produce the extracellular
matrix. Those cells that have the suffix blast will produce this
matrix while those cells with cyte at the end of the word will
maintain the matrix. Those cells whose name ends in clast will
break the matrix down. Examples of this terminology are:
osteoblasts, osteocytes and osteoclasts.
The extracellular matrix of connective tissue has 3 major
components:
1. Protein fibers (examples = collagen and elastin)
COLLAGEN: is the most abundant protein in the body ELASTIN: a
protein that can recoil and return to the original shape after
being stretched or compressed.2. Ground substance consisting of
nonfibrous proteins and other molecules
3. Fluid
General Characteristics of Connective Tissue:
a. Cells are usually scattered. Substance in between the cells
is the MATRIX.
b. Connective tissue is not located on surfaces.
c. Most connective tissue has a nerve supply (exception:
cartilage)
d. Connective tissue is highly vascularized (exceptions:
cartilage and tendons)
e. The matrix may be solid, fluid, semifluid depending upon
which tissue it is. Example: Blood has a fluid matrix and bone has
a solid matrix.
All connective tissue is derived from embryonic connective
tissue called MESENCHYME.
3. NERVOUS TISSUE: Although the nervous system is very complex,
there are only 2 general types of cells: neuroglia cells (glial
cells) and neurons. Neurons carry the impulses that control and
coordinate the body. Neuroglia cells do not carry impulses but
support the neurons in different ways.
Neurons are post mitotic but neuroglia cells continue to be
mitotic throughout life.
4. MUSCLE TISSUE: The purposes of muscle are movement,
maintaining posture and thermogenesis. There are 3 different types
of muscle tissue: skeletal muscle, smooth muscle and cardiac
muscle.
REVIEW YOUR LAB NOTES FOR THE CHARECTERISTICS OF EACH TYPE OF
MUSCLE
Note that skeletal muscles are under voluntary control; however,
the nervous system can cause these muscles to contract without
conscious involvement, such as during reflex movement.Also note
that although cardiac muscle is considered involuntary, a person
can learn to influence this rate though meditation and
biofeedback.
MEMBRANES
A membrane is a thin sheet of tissue that covers a structure or
lines a cavity. Most membranes are composed from EPITHELIUM and
CONNECTIVE tissue under it. The SKIN is the EXTERNAL MEMBRANE of
the body. In addition, there are 3 major categories of INTERNAL
MEMBRANES: MUCOUS MEMBRANES, SEROUS MEMBRANES, and SYNOVIAL
MEMBRANES.
1. MUCOUS MEMBRANE: consists of epithelial cells, their basement
membrane and the lamina propria (connective tissue found under the
epithelium of mucous membranes) underneath. Mucous membranes line
cavities and canals that open to the outside of the body (digestive
system, reproductive system, excretory system and respiratory
system). Many of these mucous membranes contain GOBLET CELLS or
MUCOUS GLANDS that produce MUCUS.
2. SEROUS MEMBRANE: membranes consist of SIMPLE SQUAMOUS
EPITHELIUM, the basement membrane and the lamina propria. Serous
membranes line cavities such as those found lining the chest wall
and the abdominal wall. They do not open to the exterior of the
body. The cells of the membrane produce a SEROUS FLUID that
decreases friction.
3. SYNOVIAL MEMBRANE: Synovial membranes line the capsule of
freely movable joints (shoulder, thigh). They produce a fluid that
decreases friction.
Chapter 5: Integumentary Systen
The skin is an organ because it consists of different tissues
that work together for specific purposes. It is the largest organ
of the human body.
The skin is composed of 2 general parts: the epidermis and the
dermis. The epidermis is the superficial layer of epithelium and
the dermis is the deep connective tissue.
Deep to the dermis is the subcutaneous layer (sub Q), which
consists of areolar (loose connective tissue) and adipose tissue.
Skeletal muscle is found under this sub Q. This area is also known
as the HYPODERMIS and is the site where the needle reaches in a
SUBCUTANEOUS INJECTION.
FUNCTIONS OF SKINa. Protection: protects tissues from damage of
ultraviolet light from the sun. Also is the first line of defense
against microorganisms (bacteria and viruses) and against
dehydration.b. Sensation: have receptors that can detect heat,
cold, touch, pressure and pain.
c. Temperature regulation: Body temp is controlled by blood flow
through the skin and by the activity of sweat glands.
d. Vitamin D production: When the skin is exposed to UV light, a
molecule is produced that will later be transformed into Vitamin D.
Vitamin D is important in the absorption of calcium in the
digestive system and therefore important in the strength of bones,
as well as the functioning of the nervous system and blood
clotting.
e. Excretion: excretion is the removal of waste products from
the body. In addition to water and salts, sweat contains waste
products like urea, uric acid and ammonia.
EPIDERMISThe epidermis is described as KERATINIZED STRATIFIED
SQUAMOUS EPITHELIUM.
It contains 4 different types of cells including Merkel cells,
responsible for reception of light touch and Langerhans cells,
involved in the immune system.
However, the main 2 types are keratinocytes and the
melanocytes.
1. KERATINOCYTES: comprises 90% of all of epidermal cells. These
cells produce the protein KERATIN, which waterproofs the skin.
2. MELANOCYTES: produces the pigment MELANIN. Melanocytes exist
in the lower portion of the epidermis and transfer their melanin to
keratinocytes by pinocytosis.
There are 4 to 5 regions (strata) of cells that compose the
epidermis, depending where the skin is located.
Most of the skin will have only 4 layers. When an area is
exposed to friction constantly, like the palms of the hands and the
sole of the feet, the epidermis will have a 5th layer.
stratum corneum: consists of 25 - 30 layers of flat dead
squamous cells that are completely filled with keratin. They will
be continuously shed (DESQUAMATE) and replaced by deeper cells.
stratum lucidum: 3-5 layers of clear, flat dead cells. Found
only on palms and soles of feet (= thick skin)stratum granulosum:
3-5 layers of cells. Keratin begins to be formed and the nuclei of
the keratinocytes begin to degenerate.
stratum spinosum: 8 -10 layers of cells where uptake of melanin
from melanocytes to keratinocytes occurs.
stratum basale: Singles layer of stem cells that are continually
going through mitosis producing new keratinocytes. Melanocytes also
found in this area. The cells multiply, produce keratinocytes that
push towards the surface of the skin. The nuclei will eventually
degenerate because the cell is moving further away from the O2 and
nutrient source, the blood. The cells die and become filled with
keratin by the time they reach the stratum corneum.It takes
approximately 40-56 days for a cell to be pushed up from the s.
basale to the top portion of the s. corneum. Once they reach the
top layer, they desquamate. At time of birth, the infant has VERNIX
CASEOSA covering his/her skin. This is a waxy white substance
coating the newborn that is secreted by the fetus sebaceous glands
beginning at 20 weeks gestation. It is theorized to have antibiotic
properties.SKIN COLOR:
3 pigments are responsible for the color of skin: melanin,
carotene and hemoglobin.
1. Melanin: This is the most important group of pigments in
skin, hair and eyes. Melanin molecules have different colors,
ranging from yellow to reddish-brown to black. It is also the only
one of the 3 pigments that is actually produced in skin cells, the
MELANOCYTES and is thought to provide protection against UV light
from the sun. The amount that is there will determine if the skin
is pale or black. The number of melanocytes is about the same in
all races - it is the amount of pigment that each cell produces
that differs among the races.
The amount of melanin produced by each melanocyte, the melanins
color, and the distribution of these cells are determined by:
a. Geneticsb. Exposure to light (environment). Exposure to UV
rays (sun and tanning booths) produces a tan.
c. Hormones. During pregnancy, when hormone levels are high, a
woman may experience darkening around the eyes known as a mask of
pregnancy, an appearance of a line on the middle od the abdomen as
well as darkening of the nipples.
Melanin is synthesized from an amino acid, tyrosine, in
melanocytes in the presence of an enzyme called TYROSINASE.
tyrosine -------------------------( melanin
tryrosinase
Exposure to UV radiation (sunlight) will increase the enzymatic
activity of tyrosinase and lead to more melanin production. The
skin will become darker, or tan, offering protection from UV
radiation to the body. Note that sunless tanning preparations cause
a chemical reaction with the keratin in the epidermal cells,
resulting in a pigment.An inherited lack of melanin formation is
ALBINISM. Individual has melanocytes and tyrosine but do not
produce tyrosinase and therefore are unable to produce melanin.
They lack color in their hair, eyes and skin. SUNLESS TAN lotions
work by chemically reacting with the keratin in the epidermal
keratinocytes
2. Carotene: This is a yellowish-orange pigment that can
accumulate in the stratum corneum and subcutaneous layer. The
individuals diet is the source of this pigment and those
individuals who eat a lot of carrots can develop an orange cast to
their skin, due to the large amount of carotene in carrots.
Decreasing the ingestion of these foods will decrease the deposit
and therefore the yellow tinge to the skin.3. Hemoglobin: This is
the red pigment found in red blood cells that carries oxygen. In
the skin of Caucasians, where there is little melanin, the skin
appears pink.
DERMISThe dermis is composed of connective tissue containing
collagen and elastic fibers.
COLLAGEN: a protein that gives connective strength and
pliability. It is the most abundant protein in connective tissue.
ELASTIN: also a protein that gives skin plasticity.
The dermis is subdivided into 2 parts: the more superficial
papillary region and the deeper reticular region. If the skin is
overstretched as in a pregnancy or fast increase in muscle or fat
deposits, the dermis may tear and leave lines through the epidermis
called STRIAE, also called stretch marks.There are 3 types of
injections:1. INTRADERMAL injection: (tuberculin skin test)
injection into the dermis
2. SUBCUTANEOUS injection: injection into the fatty tissue of
the hypodermis referred to as a SUB-Q injection
3. INTRAMUSCULAR injection: an injection into the skeletal
muscle deep to the hypodermis. Referred to as an IM injection.
The border between the epidermis and dermis is not straight but
contain distinctive rising areas referred to as DERMAL PAPILLAE.
These ridges are reflected onto the overlying epidermis and will be
responsible for fingerprints and footprints. These patterns are
unique to each individual, including identical twins.Tattoos and
the dermis: Tattooing involves the placement of pigment into the
skin's dermis. After initial injection, pigment is dispersed
throughout the damaged layer down through the epidermis and upper
dermis, activating the immune systems phagocytes to engulf the
pigment particles. As healing proceeds, the damaged epidermis
flakes away, eliminating surface pigment. In the dermis, the injury
stimulates the formation of new connective tissue cells,
fibroblasts, that will trap the pigmented phagocytes just below the
dermis/epidermis boundary. Its presence there is very stable, but
in the long term (decades) the pigment tends to migrate deeper into
the dermis, accounting for the degraded detail of old tattoos. The
dermis also has structures like hair follicles, glands, and nails
are called Accessory Skin Structures.Accessory Skin Structures =
glands, nails, and hair (epidermal derivatives)
Glands:1. Sebaceous glands: These are oil glands that are
located in the dermis and usually connected to hair follicles. The
SEBUM from these glands prevents the hair from becoming brittle and
breaking and maintains the moisture of the skin.
2. Sudoriferous glands: These are sweat glands located
throughout the body. There are 2 types: merocrine and apocrine.
a. Merocrine (eccrine) sweat glands are more abundant than
apocrine. The sweat from these glands is very watery and they are
responsible for temperature homeostasis
b. Apocrine glands are mostly found in the axillary and groin
areas. They become active at time of puberty. The sweat from these
glands is viscous and is produced during stress or excitement.
Bacteria grow rapidly on this secretion and the breakdown of the
sweat by the bacteria can lead to body odor. Influenced by sex
hormones.
Emotional sweating is used in polygraph tests (lie detectors)
and is based on the idea that lying is a stressful activity that
causes sweating. Due to the salt content of sweat, a small amount
of electricity can be conducted through this secretion and
measured.
3. Ceruminous glands: These are modified sweat glands that are
found only in the outer ear. They produce a waxy secretion called
CERUMEN, which offers protection from some debris.
4. Mammary glands: These are modified sweat glands located in
the breasts that, under the control of hormones, produce milk for
newborns.
Nails: These are plates of tightly packed, hard, keratinized
cells that lie over epidermis of the dorsal, distal portion of
digits. The LUNULA is a thickened area of the nail that covers the
matrix, the mitotically active.
Nails grow from the base, do not have a resting period and
fingernails grow faster than toenails.Hair (pili): characteristic
of all mammals is the presence of hair. In humans, hair is found
most places on the body.
By the 5th month of fetal development, the fetus body is covered
by unpigmented hair called LANUGO. Near the time of birth, TERMINAL
HAIRS that are course and pigmented, replace the lanugo on the
scalp and eyebrows. VELLUS HAIRS, which are short and fine, replace
the lanugo on the rest of the body. At time of puberty, terminal
hair in the pubic, axillary regions, and in males on the chest and
face, replaces the vellus hair. The main functions of hair are
protection, decrease in friction (in pubic region during sexual
intercourse), and odor retention associated with sexual
arousal.
A hair is composed of columns of dead keratinized epithelial
cells. The SHAFT of the hair projects above the skin, while the
ROOT is the portion that is beneath the skin. Surrounding the hair
is the HAIR FOLLICLE. At the base of the hair follicle is the BULB
that contains the mitotically active cells. Sebaceous glands are
closely associated with the hair follicle, as is an ARRECTOR PILI
muscle, a smooth muscle that will lift the hair when it contracts,
causing goose bumps in humans.
Hair is produced in cycles that involve a growth stage and a
resting stage and is dependent upon where it is located. Eyelashes
grow for 30 days and rest for 105 days, while scalp hair grows for
a period of 3 years and rests for 1-2 years. At any given time, 90%
of scalp hair is in a growing stage. There appears to be maximum
lengths that hair will grow to, genetically determined.
Loss of hair can indicate a problem. Temporary loss can be due
to drugs, diet, stress, and high fevers. Hormonal changes can also
result in hair loss and cause a shift from terminal hair to vellus
hair production beginning at the temples and spreading to the crown
of the head. This is a genetic condition seen in men and is
referred to as male pattern baldness. Pregnant females may also see
a change during the 9 months.
Medication used to promote hair growth in balding individuals,
example Minoxidil, was originally a blood pressure medication. This
is sold over the counter as ROGAINE.
Hair colorThe color of hair is determined genetically. It is
produced by melanocytes within the hair bulb and passed to the
keratinocytes of the hair cortex and medulla. Blonde hair has a
small amount of melanin whereas black has much more. Lighter brown
hair has a smaller amount of lighter melanin and red hair contains
melanin that has more copper in it. As aging occurs and protein
synthesis decreases, the amount of melanin in the hair decreases,
resulting in a gray-white color.
HYPODERMISThe hypodermis is the underlying connective tissue of
the skin, mostly consisting of adipose. Its purpose is to connect
the skin to the skeletal muscle. This is not anatomically
considered part of the skin and is referred to as hypodermis,
subcutaneous tissue or superficial fascia.
Half of the adults body fat is stored in the hypodermis, which
functions to store energy, protection and insulation of the body.
The amount of fat is dependent upon age, sex, diet and
genetics.
The Skin and Homeostasis
THERMOREGULATION AND THE SKIN:
One of the functions of the skin is to help maintain the
homeostasis of the body temperature at 37 C. If the environmental
temperature is high, heat receptors in the skin will send impulses
to the brain.
The brain then sends impulses to the sweat glands to produce
perspiration. As this fluid EVAPORATES from the surface of the
skin, the skin is cooled off and returns to normal. Also, more
blood will be circulated to the skin and will release heat to the
outside of the body.
In the cold, the brain will send information to the muscle layer
of blood vessels causing them to constrict. When this occurs, less
blood will go into the vessels of the skin and therefore less heat
will be lost.
The Skin and Administering medications: Some lipid-soluble
medications pass easily through the skin. These tend to slowly
diffuse through into the blood and be taken to other parts of the
body. Examples include nicotine patches, birth-control patches, and
Dramamine patches. Other epithelial coverings, like mucus
membranes, also allow for absorption such as the mucous membrane in
the mouth used for administration of NITROGLYCERIN for chest pain
and the mucous membrane in the rectum, used for administration of
medication thought suppositories. The Skin and Burns: Tissue damage
due to heat, electricity, radioactivity or strong chemicals that
DENATURE proteins in the exposed cells is called a BURN. Generally,
the SYSTEMIC effects of a burn are greater than the local
effects.
Classification of Burns:Depending upon the depth, burns are
classified as PARTIAL-THICKNESS BURNS that are subdivided into
first and second degree burns or FULL THICKNESS BURNS that are also
referred to as third degree burns.
First-degree burn: involves only the surface epidermis, mild
pain and redness with no blisters. Typical sunburn.
Second-degree burn: destroys all of the epidermis and may
destroy some of the papillary region of the dermis. Redness,
blisters, edema and pain are the symptoms. No injury to accessory
skin structures. The regeneration of skin occurs from the epidermis
of the hair follicles, sweat glands and from the unharmed tissue
around the involved area.Third-degree burn: destroys epidermis,
dermis and epidermal derivatives and may also involve deeper
tissue. They may also be surrounded by areas that have suffered
first and second degree burns which still may be sensitive the
third degree burned areas no longer have dermal sensory receptors
so may not experience feeling. Skin functions are lost and
regeneration can only occur from tissue in adjoining areas. Often,
skin grafts are necessary.Serious burns destroy the bodys first
line of defense, making the person susceptible to infections.
A major burn of the face can lead to respiratory problems while
those in the joints lead to scar tissue formation that restricts
movement. Deep partial burns and full thickness burns can result in
scar tissue that experiences contracture disfigurement follows.
SKIN GRAFTS are performed to avoid this and to speed healing. In a
SPLIT SKIN GRAFT, the epidermis and part of the dermis are removed
from another part of the body and placed over the burned area.
Interstitial fluid nourishes this graft and the dermis becomes
vascularized. The area that the graft was taken from still
maintains some of its dermis and therefore will still have
accessory structures containing epithelium within them. These hair
follicles and sweat glands will be the source of the new
epithelium.When the loss of skin is so extensive that conventional
grafting is not possible, a self-donation procedure is used in
which small amounts of an individuals epidermis are removed and
grown in a lab. This will produce sheets of new skin. These will be
transplanted back to the person where needed and is termed
AUTOLOGOUS SKIN TRANSPLANTATION. This new skin will only be
epidermis and does not contain glands or hair. This procedure takes
3-4 weeks. A person needs some type of covering to protect him
during this time. During the waiting period, skin from a human
cadaver may be used (homograft) or from another animal, like a goat
(heterograft).
When burns are extensive, the bodys first mode of defense is
destroyed and it is left vulnerable to infection. The patient is
maintained in an ASEPTIC environment to decrease exposure to
microorganisms that could enter and cause infection. ANTIBIOTICS
are given as a PROPHYLACTIC step and DEBRIDEMENT is also done. This
is the removal of dead tissue from the burned area, which helps to
clean the wound and remove tissue in which infection could develop.
Maggots can be used.Despite all the procedures available, infection
is the major causes of death among burn victims.
There is also generalized depression of the immune system
because the burned tissue is recognized as a foreign substance and
overwhelms the immune system. There will be a decrease in the
activity of the cells and substances of this protective mechanism
and the body is more susceptible.
Aside from the threat of infection, the LOSS OF FLUIDS is
another problem facing the patient as well as an increase in the
occurrence of BLOOD CLOTS in blood vessels. This is due to an
increase of clotting factors in the blood (due to a decrease in
fluid volume).
Physiological Changes and Burns:
Within minutes of a deep burn, capillaries become more
permeable, allowing for the release of fluid from the blood into
the tissue spaces. This results in EDEMA (swelling) and a decrease
in the amount of blood in the cardiovascular system. This decrease
in blood volume can lead to tissue damage due to lack of adequate
oxygen, shock and death. The change in the tissue of the blood
vessels can lead to blood clotting.Self Investigation: What is the
RULE OF NINES? Does it apply to both adults and infants?(a) In an
adult, surface areas can be estimated using the rule of nines: Each
major area of the body is 9%, or a multiple of 9%, of the total
body surface area. (b) In infants and children, the head represents
a larger proportion of surface area, and so the rule of nines is
not as accurate for children, as can be seen in this illustration
of a 5-year-old child.
SKIN PATHOLOGY:Skin cancer: Skin cancer is the most common type
of cancer and is usually associated with overexposure to the sun or
TANNING LIGHTS. With exposure, the DNA in the skin cells change
(mutate) leading to uncontrolled cell division and abnormal
behavior. Melanin protects the DNA those with fair skin and less
melanin are more susceptible to skin cancer.3 most common forms of
skin cancer:
1. BASAL CELL CARCINOMA: Accounts for 75% of all skin cancer.
Tumors arise from s. basale of epidermis and have a variety of
appearances. Usually slow metastasis.2. SQUAMOUS CELL CARCINOMA:
This is the second most common skin cancer that arises from the s.
spinosum. Usually slow metastasis.3. MALIGNANT MELANOMA: This is a
life- threatening CA arising from melanocytes, many times found
within a preexisting mole. Treatments of melanomas, which are
confined to the epidermis, are usually successful however,
melanomas metastasize rapidly therefore early detection is
important. Remember the ABCDE rule when examining a possible
melanoma
A = asymmetry (one side of the lesion does not match the
other)
B = border irregularityC = color pigmentation is not uniform
D = diameter greater than 6mm
E = evolving lesion changes appearance over time.OTHER
PATHOLOGIES of the skinDecubitus: bedsore or pressure sore; caused
by prolonged deficiency of blood to tissues overlying a bony
projection. The deficiency causes a breakdown of the skin resulting
in cracking, infection, and deep damage. Commonly seen in patients
that are bedridden for a long time, on buttocks, sacrum, and heels.
Turning is necessary.Psoriasis: Chronic skin condition in which the
skin cells divides 7 times more frequently than normal. This leads
to excessive cell accumulation, seen as scaly reddened patches on
skin surface. Some cancer drugs can be used for treatment.Vitiligo:
The development of patches of white skin due to abnormal or lack of
melanocytes in an area. May be an autoimmune response.
Vocabulary:
Cyanosis: a bluish color caused by decreased blood oxygen
content, is an indication of impaired circulatory or respiratory
functionJaundice: A yellowish skin color, can occur when the liver
is damaged by a disease such as viral hepatitis.Impetigo (know
symptoms and what causes it): usually produces blisters or sores on
the face, neck, hands, and diaper area. It is primarily caused by
Staphylococcus aureus, and sometimes by Streptococcus
pyogenes.Erythema: is increased redness of the skin resulting from
increased blood flow through the skin.Chapter 6: Bone Tissue and
the Skeletal SystemThe skeletal system has 4 components bone,
cartilage, tendons, and ligaments all are different types of
connective tissue.Functions of Bone:
1. SUPPORT: Bones provide a hard framework that ANCHORS soft
tissue of the body.
2. PROTECTION: to internal organs by this hard tissue that
overlies and/or surrounds them.
Example: cranium and brain, spinal cord and vertebral column
3. MOVEMENT: bones provide leverage for muscle contraction.
4. STORAGE: Some minerals in the blood, like calcium, are taken
into the bone and stored. When levels in the blood decrease, the
minerals move from the bone into the blood, maintaining a
homeostatic level. Also adipose tissue, a source of energy, is
stored in the YELLOW BONE MARROW within bone cavities.
5. BLOOD CELL PRODUCTION: occurs in RED BONE MARROW of certain
bones (cranium, sternum, ribs, vertebrae, sacral and hip bones (Os
coxae), head of femur and humerus). The production of blood cells =
hemopoiesis
CARTILAGE
As with bone, cartilage is a component of the human skeletal
system. These 2 tissues are closely related to each
other.CHONDROBLASTS are cells that produce new cartilage matrix.
When this material surrounds these cells, there is a decrease in
the O2 level and they differentiate into mature cartilage cells,
the CHONDROCYTES, which maintain the cartilage. This round cell is
found within LACUNAE.
Blood vessels and nerves are found only in the perichondrium and
dont enter the cartilage itself. Therefore, nutrients and oxygen
diffuse through the cartilage matrix to the cells. Due to this low
level of needed materials, cartilage takes a long time to heal.
PERICHONDRIUM is a double layer of connective tissue that is
found on the outside of cartilage. Blood vessels and nerves
penetrate the outer portion of this sheath but not the cartilage
itself. Therefore nutrients must diffuse from these blood vessels
to the chondrocytes.
There are 3 types of cartilage hyaline cartilage, fibrocartilage
and elastic cartilage. They are located in different areas of the
body. The difference is dependent upon how flexible the matrix
is.
1. Hyaline Cartilage: The most abundant type of cartilage, found
at the ends of long bones and in the costal (rib) area. Also seen
in the embryo as the material that will be replaced by bone in
endochondral ossification: very strong, but not very flexible.
2. Fibrocartilage: Tough but flexible cartilage. Seen forming
intervertebral discs and pubic symphysis. The matrix has a lot of
collagen.
3. Elastic Cartilage: Very flexible. Contains many collagen and
elastin fibers in matrix.
Example: pinna of the ear.MESENCHYME LEADING TO CARTILAGE and
BONE FORMATIONDuring embryological development, MESENCHYME STEM
CELLS or MSCs (embryological connective tissue), gives rise to all
definitive connective tissue, such as blood, adipose, cartilage,
among others. Bone is also included in this group because of its
connective tissue classification.
Some mesenchyme gives rise to OSTEOCHONDRAL PROGENITOR CELLS, a
type of stem cell. These eventually will become cartilage or bone.
OCPCs are located in the perichondrium, the periosteum, and the
endosteum.
This development from one type of cell into another is referred
to as DIFFERENTIATION the process by which cells undergo a change
toward a more specialized form or function.HISTOLOGY OF BONE:
Osseous tissue consists of widely spread cells, separated by
matrix.
4 Principal Osseous Cells:
1. OSTEOCHONDRAL PROGENITOR CELLS: All connective tissue
develops embryologically from MESENCHYME cells. Some of these
mesenchyme cells become Osteochondral Progenitor Cells. These cells
are stem cells, able to go through mitosis. They eventually become
osteoblasts or chondroblasts.
2. OSTEOBLASTS: cells that form bone but no longer can go
through mitosis.
They will secrete material that will compose the matrix of the
bone, like collagen.
All osteoblasts are derived from osteochondral cells.
OSSIFICATION (osteogenesis): formation of bone by
osteoblasts.
3. OSTEOCYTES: mature bone cells that are derived from
osteoblasts-they are the main cell of osseous tissue and maintain
the bones matrix. No mitosis occurs in these cells. They
differentiate from osteoblasts as the osteoblasts surround
themselves with matrix and reduce O2 supply.
Osteoblasts originally form bone tissue and osteocytes maintain
daily cellular activity. Osteocytes are found within LACUNAE. They
are cells that have long processes that run through the CANALICULI
and come into close contact with those processes of other
osteocytes. Diffusion of O2 and nutr\ients is possible.
Mesenchyme cells( osteochondral progenitor cells ( osteoblasts (
osteocytes
4. OSTEOCLASTS: Derived from stem cells in the red bone marrow
(not from the osteochondral progenitor cells in bone and
cartilage). They will settle on surfaces of bone and are
responsible for RESORPTION or breakdown of the matrix. This
resorption of bone is important in the growth and repair of bone
and is a natural process that is constantly occurring. In health,
resorption is in balance with OSTEOGENESIS (formation of new bone
by osteoblasts). These cells have many nuclei and have ruffled
edges.
BONE MATRIXThe MATRIX of bone is solid, composed of 35% organic
and 65% inorganic material. The organic material consists primarily
of the protein collagen. The inorganic material is primarily of a
calcium phosphate crystal called HYDROXYAPATITE. The collagen is
responsible for flexibility and the inorganic material gives it
strength.These salts are deposited in the framework of COLLAGEN
FIBERS, which gives flexibility to the hard inorganic material. It
is produced by osteoblasts.
PATHOLOGY OSTEOGENESIS IMPERFECTA: genetic disease in which
there is a mutation in a gene governing the formation of collagen.
The result varies but less collagen will be produced, leading to
abnormal bone formation as well as decrease strength and
flexibility in tendons. Osteogenesis Imperfecta can be either
barely noticed by the patient or can result in death soon after
birth due to fracture of the extremities occurring before and
during birth and an inability to breathe because of small thorax
and rib fractures.
ARRANGEMENT OF BONE - CANCELLOUS and COMPACT BONE
Compact Bone: An arrangement of bone tissue that is very tight
and dense. Because of this, compact bone will be arranged in
OSTEONS, a system of osteocytes that are arranged around a
HAVERSIAN CANAL, which contains blood vessels.
Compact bone composes the outside of all bones.
Cancellous Bone (spongy bone): An arrangement of bone that
consists of separate plates called TRABECULAE. Between these
trabeculae are spaces filled with bone marrow and blood
vessels.
NO OSTEONS EXIST IN CANCELLOUS BONE. This type of arrangement
makes up the internal portion of bone.
BONE ANATOMY
STRUCTURE OF A LONG BONE:
DIAPHYSIS: The shaft of the bone
EPIPHYSIS: The extremities or ends of the bone.
EPIPHYSEAL GROWTH PLATE: growth area of bone (originally hyaline
cartilage). This area closes as person ages and is known as
EPIPHYSEAL LINE.
ARTICULAR CARTILAGE: thin layer of hyaline cartilage covering
surface of bone where it meets another bone within a joint; reduces
friction.
PERIOSTEUM: membrane around the surface of the bone, except
where there is articular surface.
MEDULLARY CAVITY: space within the diaphysis that contains the
yellow marrow and, in specific bones, red marrow.
ENDOSTEUM: membrane lining of medullary cavity.
BONE DEVELOPMENT
The skeleton during early development is composed of fibrous
connective tissue and hyaline cartilage, not bone. As the embryo
develops, bone will replace these 2 types of tissue.
Ossification (production of bone tissue) begins at about 5 weeks
gestation and continues throughout a persons life.
There are 2 types of ossification, based on the original tissue
that the bone replaces INTRAMEMBRANEOUS OSSIFICATION and
ENDOCHONDRAL OSSIFICATION.
1. INTRAMEMBRANEOUS OSSIFICATION direct ossificationa. At about
5-6 weeks of development, mesenchyme forms a fibrous connective
tissue membrane around the brain and where the mandible and
clavicles will be.
b. These mesenchymal cells become osteochondral progenitor cells
that then become osteoblasts.
c. As the osteoblasts produce matrix, they differentiate into
osteocytes due to a decrease in oxygen.
Bone has been formed directly from mesenchyme, within a
membrane. In humans, this type of ossification occurs only in the
flat bones of the skull, mandible and clavicles.
2. ENDOCHONDRAL OSSIFICATION indirect ossification This is the
method that most bones in the human body are formed.
a. Mesenchymal cells collect in regions of where bone will
form.
b. Mesenchymal cells differentiate into osteochondral progenitor
cells.c. Osteochondral progenitor cells become chondroblasts and
form a HYALINE CARTILAGE MODEL, which will have the same shape as
the bone that will later be formed will have. These cells become
surrounded by cartilage matrix, decrease O2 and differentiate into
chondrocytes. A hyaline cartilage model has been formedd. Blood
vessels invade this cartilage model bringing with them
osteochondral progenitor cells that become osteoblasts, replacing
the chondrocytes. These osteoblasts produce bone that replaces the
cartilage, starting at the PRIMARY OSSIFICATION CENTERS of each
bone.
e. Replacement of cartilage by bone continues until all of the
cartilage, EXCEPT IN THE EPIPHYSEAL PLATES, is replaced by bone. In
mature bone, these plates will also ossify, restricting future
elongation and be referred to as EPYPHSEAL LINES.
Summary
Mesenchymal cells ( osteochondral progenitor cells (
chondroblasts which form a
small cartilaginous model of the bone(
Chondroblasts differentiate into ( blood vessels invade the
cartilaginous model
Chondrocytes due to decrease in O2 bringing a new population of
OCPC with them (OCPC become osteoblasts, ( Osteoblasts eventually
become osteocytes due to decrease in O2.
which form matrix in all areas BONE is formed.
except epiphyseal growth plate.
Note that in ENDCHONDRAL OSSIFICATION, the development of bone
is not direct. The structure is first hyaline cartilage and then is
replaced by bone.
Ossification of all bones will be complete by age 25, with the
medial epiphysis of the clavicle being the last to stop
growing.FACTORS AFFECTING BONE GROWTHa. Geneticsb. Nutrition: The
formation of bone is dependent upon mitosis and differentiation of
stem cells. Any metabolic disorder that affects overall health will
effect rate of mitosis and therefore have serious effects on
skeletal growth. VITAMIN D is important for absorption of CALCIUM
from the digestive system. c. Hormones: GROWTH HORMONE, a hormone
from the pituitary gland of the brain, is important in bone
formation and growth. THYROID HORMONE and PARATHYROID HORMONES are
also important in growth.SEX HORMONES are also important in bone
growth. Estrogens (female sex hormones) and testosterones (male sex
hormones) initially stimulate bone growth. When there is an
increase in these hormone levels around puberty, a growth spurt
will follow. However, these hormones that initially stimulate
growth are also responsible for closure of the epiphyseal plates
and therefore are responsible for stopping growth. It has been
hypothesized that estrogens cause a quicker closure and that is why
females tend to be shorter than males.
Remodeling is the ongoing replacement of old bone tissue by new
bone tissue.
Bone tissue is never at rest and changes are constantly
happening, even after the bone reaches its final length and
shape.
This remodeling will take place at different rates, depending
upon the bone and the age of the person. The distal portion of the
femur will be replaced every 4 months, while the shaft will not be
completely replaced after the individual reaches adulthood.
Two other hormones involved in bone development are PARATHYROID
HORMONE and CALCITONIN, antagonistic hormones, and together will
regulate the balance of calcium between the bone and the blood and
are therefore vital in bone remodeling.
BLOOD CALCIUM HOMEOSTASIS: Bones are important in regulating
blood calcium levels that must be maintained within tight limits.
PTH and Calcitonin are 2 antagonistic hormones that work together
to maintain homeostatic blood calcium levels
Parathyroid Hormone (PTH) is a hormone of the parathyroid glands
and is the major regulator of blood calcium levels. When the blood
calcium level decreases, the secretion of PTH increases, resulting
in an increase in the activity of osteoclasts.
PTH: AIM increase calcium level in the blood Ca+2 derived from
bone.
PTH also has an effect on the kidneys and digestive system that
will act to increase calcium levels in the blood.
Cancerous tumors can secrete hormones that the normal tissue
would not do (paraneoplastic syndrome). When a malignant neoplasm
secretes PTH, bones become very thin and break easily. The increase
in Ca+2 in the blood can also cause problems.
Calcitonin is a hormone that is secreted by the thyroid gland
and decreases osteoclast activity, leading to a decrease in blood
calcium concentration. High levels of calcium in the blood
stimulate synthesis and release.
Calcitonin: AIM decrease calcium level in the blood. Calcium is
taken into the bone.
The concentration of calcium must remain within homeostatic
levels or pathologies occur.
STEPS IN BONE REPAIR:
Bone is a living tissue that can be repaired after damage is
done to it.
FRACTURE: any break in a bone.
a. HEMATOMA FORMATION:HEMATOMA: a localized mass of blood
confined within an organ or space.
When a fracture occurs, the blood vessels in the area are
broken, blood rushes into the injured area and a clot forms 6-8
hours after injury.
Osteocytes around the site die due to a disruption of the blood
and therefore of oxygen.
Inflammation occurs, bringing phagocytic cells (white blood
cells) and osteoclasts into the area to clean up the dead and dying
bone cells.
b. CALLUS FORMATION: CALLUS: mass of tissue that forms at the
fracture site and attempts to connect the broken ends of the
bones.
This connective tissue will be invaded by chondroblasts from the
periosteum and endosteum of the broken bone. Cartilage is formed
and chondoblasts become chondrocytes.
c. CALLUS OSSIFICATION:Similar to fetal development, the
chondrocytes will eventually be replaced by osteoblasts and new
bone will be formed.
d. REMODELING OF BONE:The final phase of fracture repair is
REMODELING of the bony callus by osteoblasts and osteoclasts.
Repair may be so complete that no evidence of a break remains.
However, the repaired area may remain slightly thicker.
In order for this fracture repair to occur, the 2 portions of
the broken bone must be located very near to each other and held
stationery. If this is not possible, another material must be used
to join the bone living bone from another, dead bone from a
cadaver, or a type of coral that resembles cancellous bone.
EXERCISE AND BONE
Bone can become stronger in response to mechanical stress,
including walking. When a person is immobile, the bone will
decrease in strength and size. This is also observed when a cast
immobilizes a limb and when an astronaut is in space where there is
no gravity. Mechanical stress applied to bone increases osteoblast
activity.
AGING AND BONE LOSS:
With age there is a decrease in bone mass. This is due to, in
women, a decrease in estrogen with menopause, which leads to a
decrease in calcium deposits in matrix. Also seen in men usually
not until age 60 due to decrease in testosterone.
With age, there is also an overall decrease in protein
synthesis. For bone, this means a decrease in the amount of
collagen and elastin made and therefore a decrease in bone strength
and flexibility. The chance of bone fractures, especially hip
fractures will increase with age, and these fractures take a longer
time to repair.
OSTEOPOROSIS is a pathology that leads to porous bones. It is
characterized by decrease bone mass and the bones are more likely
to fracture.
In this condition, bone resorption (osteoclasts) occurs faster
than bone formation (osteoblasts). It affects middle age and older
people, primarily women.
Osteoporosis is also seen in young people whose caloric intake
is inadequate, those with eating disorders and those with low fat
content (ballet dancers).
The beginning of bone loss is OSTEOPENIA.
First sign of osteoporosis may be a PATHOLOGICAL SPONTANEOUS
FRACTURE, where the bone becomes so thin that it cannot take the
stress of everyday life.
Chapter 7: Axial Skeleton and Chapter 8: Appendicular
Skeleton
(note: majority of this information will be covered in lab)The
bones can be classified according to shape. Long bones, short bones
(tarsals and carpals),
flat bones (cranial bones), irregular bones (vertebrae), Wormian
bones (skull), and sesamoid bones (small bones embedded in tendons
like the patella).
DIVISION OF THE HUMAN SKELETON:
The adult human skeleton consists of approximately 206 bones
divided into 2 subdivisions; the AXIAL SKELETON and the
APPENDICULAR SKELETON.
AXIAL SKELETON: skull, vertebral column, ribs, sternum, hyoid,
and ossicles
APPENDICULAR SKELETON: pectoral girdle (clavicle + scapula),
humerus, radius, ulna, carpals, metacarpals and phalanges, and
pelvic girdle (os coxae), femur, tibia, fibula, tarsals,
metatarsals and phalanges.
At birth, the human has approximately 270 bones. Some of these
bones will ossify together with time, resulting in a smaller number
in the adult, approximately 206.
Most of this work has been completed in the lab. The following
are a few extra facts about the bones.
AXIAL ADDITIONS:
SKULL: The skull of a newborn consists of fibrous connective
tissue areas that have not yet ossified. These soft spots are
called FONTANELS and enable the fetal skull to modify it size and
shape during a vaginal delivery, and to adjust to the increase in
the size of the brain. The ANTERIOR FONTANEL is the largest and
finishes ossifying at 2 years of age.
Note that the top portion of the skull (skullcap) is termed the
CALVARIA.
The skull may have a few extra small bones referred to as
WORMIAN BONES, existing within sutures.
There is one type referred to as an INCA BONE which is larger
than most and midline between the junction of the lambdoidal and
sagittal sutures. This bone was common in the skulls of the Incas
and is still present in their Andean descendants.
A SINUS is an opening within a bone that is lined with mucous
membrane. The bones around the nasal cavity have large sinuses
within them called the PARANASAL SINUSES. These empty areas will
decrease the weight of the skull and act as a resonating chamber
for the voice. There are sinuses in the frontal, maxillary,
ethmoidal and sphenoidal bones.
NASAL SEPTUM: There is one NASAL CAVITY that is divided by a
NASAL SEPTUM (Septum = division). This anatomical wall between the
2 NOSTRILS is composed of the PERPINDCULAR PLATE of the ETHMOID
BONE, the VOMER and the anterior SEPTAL CARTILAGE (pg. 206).
This is located mid-sagitally but can be injured by a trauma and
is placed laterally to one side. This is a DEVIATED SEPTUM that may
be severe enough to cause difficulty in breathing. Surgical repair
can be done with excellent results.
Fracture of the Cribriform Plate of the ethmoid bone -
Trauma can pierce the membranes around the brain and cause the
loss of clear cerebrospinal fluid (CSF) through the nose. Because
of this, infection is very possible.CLEFT PALATE: usually the
palatine processes of the maxillary bones unite during 10-12 weeks
gestation. If this does not happen, a CLEFT PALATE can occur. This
is a condition in which there is an opening between the oral and
nasal cavity and feeding the infant is difficult. Surgical results
are excellent. In many instances, a CLEFT LIP accompanies this
condition. As with the hard palate, anterior portion of the
maxillae do not fuse with each other.
HYOID BONE: U shaped bone, unique because it does not articulate
with other bones. It is found between the mandible and the larynx
and provides attachment for muscles of the tongue.
VERTEBRAL COLUMN: composed of 26 bones, distributed in 5
regions: 7 cervical vertebrae, 12 thoracic, 5 lumbar, the sacrum (5
FUSED vertebrae) and coccyx (4 FUSED vertebrae).
(Think: breakfast, lunch, and dinner at 7, 12, and 5)
There are INTERVERTEBRAL DISKS in between the bodies of adjacent
vertebrae. These structures are composed of fibrocartilage and are
shock absorbers.
PATHOLOGY: HERNIATED (ruptured) DISK (slipped disk)This
pathology occurs when there is a rupture of a portion of the disk
so that it is dislocated and leans on spinal nerves. Can be very
painful. Surgical intervention may be useful, removing a portion or
the entire disk and, when needed, fusing 2 vertebrae together.
There are 4 NORMAL CURVATURES of the spinal column: The infant is
born with the THORACIC and SACRAL curvatures. As the child lifts
his head, the CERVICAL CURVATURE develops. As the child becomes
BIPEDAL, the LUMBAR CURVATURE develops
ABNORMAL CURVATURE OF THE SPINE:
SCOLIOSIS: lateral bend of the vertebral column, usually in the
thoracic region.
KYPHOSIS: exaggeration of the thoracic curvature. Also known as
hunchback.
LORDOSIS: exaggeration of lumbar curvature. Seen in pregnancy
and also known as swayback.
APPENDICULAR ADDITIONS:
2 girdles exist to suspend the arms and legs.
PECTORAL GIRDLE: consists of the clavicle and the scapula,
joined at the ACROMIOCLAVICULAR JOINT. This is the most superior
girdle that supports the arms.
PELVIC GIRDLE: formed by the anterior PUBIC SYMPHYSIS, joining
the 2 OS COXAE.
The pubic symphysis is held together by FIBROCARTILAGE.
Chapter 9: JointsMuscles pull on bones to make them move, but
movement would not be possible without articulations (joints)
between the bones.
ARTICULATION: place where 2 bones come together. Some of these
articulations are movable but some are not.
The 3 major types of joints are classified as FIBROUS,
CARTILAGINOUS and SYNOVIAL. This classification system is based on
the type of connective tissue that binds the 2 bones together.
1. Fibrous Joints: consists of 2 bones that are united by
FIBROUS CONNECTIVE TISSUE. They have little or no movement and do
not have a joint cavity.
a. Sutures immovable joints found in skull
b. Gomphoses a peg shaped structure fits into sockets and is
held in place by connective tissue the teeth.
2. Cartilaginous Joints: bones are united by hyaline or fibrous
cartilage.
a. symphysis: a slightly movable joint where fibrocartilage
unites the 2 bones. pubic symphysis.
b. synchondrosis connecting material is hyaline cartilage.
Epiphyseal plates of long bones are temporary joints. 3. Synovial
Joints: These are joints that have SYNOVIAL FLUID and are freely
movable. Many of the joints in the appendicular skeleton are
synovial elbow, hip, knee. The ends of the bones are covered by
hyaline cartilage.Self Investigation: Joint Changes during
PregnancyQUESTIONS:
What hormones cause changes in joints of a pregnant woman?What
joint are these changes beneficial in? What types of changes
occur?
Why may the expectant mom suffer from fallen arches during
pregnancy?
What major joint of the infant be negatively affected by
increase in hormones in the mother?
GENERAL STRUCTURE of SYNOVIAL JOINTS
1. There is a joint cavity that contains 2 bones.
2. Articular cartilage covers articulating surfaces.
3. An ARTICULAR CAPSULE holds bones together. There are 2 parts
to this capsule.
a. Fibrous capsule: Superficial connective tissue that attaches
to periosteum of bones surfaces also called LIGAMENTS. LIGAMENT:
Bundle of fibers connecting bone to bone.
b. Synovial membrane: inner portion of the articular capsule
that secretes SYNOVIAL FLUID.
This is a fluid inside of a synovial joint that decreases
friction when the bones move. It has the appearance of raw eggs,
and its consistency changes, depending upon the amount of movement
- When there is no movement the synovial fluid is thick, but will
become thinner with joint movement.
This fluid also provides nourishment to the articular cartilage,
which is avascular. It contains phagocytic cells that remove debris
from the area. With over usage and stress on the joint, there may
be an increase in the production of the synovial fluid = water on
the knee is a possibility. This may need to be removed.
Other structures associated with some synovial joints:
Bursa: saclike structure filled with fluid. It is located
between the skin and bone where there is a lot of friction.
Inflamed bursa: bursitisMeniscus: pads of fibrocartilage found
within some joints.
TYPES OF MOVEMENT WITHIN SYNOVIAL JOINTS
ELEVATION AND DEPRESSION: upward and downward movement of body
part.
Example: Mandible and shrugging of shoulders.
PROTRACTION AND RETRACTION: forward and backward movement of a
body part, parallel to the ground. Example: Mandible
INVERSION AND EVERSION: movement of sole of foot inwards and
outwards
DORSIFLEXION AND PLANTER FLEXION: bending the foot towards the
body and pointing it away from the body.
SUPINATION AND PRONATION: movement of forearm so palm faces
forward (anatomical position) or posteriorly.
ADDUCTION AND ABDUCTION: movement towards the midline or
away
FLEXION AND EXTENSION: decrease or increase the angle between 2
bones
JOINT PATHOLOGY
3 types of arthritis
1. RHEUMATOID ARTHRITIS: An autoimmune disease. The body attacks
CARTILAGE and SYNOVIAL MEMBRANES of joints. There will be
inflammation of the joint, swelling, pain. If this type of
arthritis is not treated, the synovial membranes become thicker and
produce more fluid (water on the knee). There may also be abnormal
growth of tissue formed by the inflamed synovial membrane = PANNUS.
The pannus may grow large enough to distort the joints. Destruction
of the cartilage leads to the bones within the joint ossifying
together.
2. OSTEOARTHRITIS: This is a degenerative joint disease which is
much more common than Rheumatoid Arthritis. Its onset is usually
associated with aging.
There is deterioration of the articular cartilage with
osteoarthritis, but no synovial membrane involvement. There is
inflammation, pain and decrease in the use of the joint.
3. GOUTY ARTHRITIS: This is a metabolic disease.
Uric acid is a waste product produced by the cells, and much of
it will be excreted through urine. When a person has gout, they
will be producing too much uric acid - more than can be excreted.
The uric acid will build up in the blood and some will form salt
crystals that deposit in the joints, causing pain and decrease in
motion. Bones can also fuse because the crystals will wear away at
the cartilage.
Usually seen in men with a family history and usually in the
joints of the big toe.
A tophus (Latin: "stone", plural tophi) is a deposit of
monosodium urate crystals in people with longstanding high levels
of uric acid in the blood. Tophiseen in gout.
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