Tissues Hierarchy of organization Atoms molecules cells TISSUES organs Organ systems organisms populations communities ecosystems biosphere Study of tissues.

Tissues

Hierarchy of organization

Atoms molecules cells TISSUES organs

Organ systems organisms

populations communities ecosystems biosphere

Study of tissues = Histology

Tissue types

* Epithelial tissueCover exposed surfaces (linings) both external and internal

* Connective tissueFills internal spacesConnects, supports, transports

* Muscle tissue movement

* Neural tissue Transmission of information

Epithelial tissue

Covering of all exposed surfaces

CharacteristicsPolarity (apical and basal surfaces)

Attachment (basement membrane)

Tightly bound cells

Avascular (nutrients via diffusion)

Regeneration (actively in 24° cell cycle)

Epithelial tissueFunctions

Physical protectionControl permeabilitySensationSecretion (glands)

Exocrine = secretions onto epithelial surfaceEndocrine = secretions released to surrounding fluids

Cilia and microvilli

Epithelial connectionsSpecial proteins connect cells to each other at

Tight junctions Desmosomes Gap junctionsApicalIn-between epi cellsKeeps fluids

from leaking between cells

Connect cell to cell

Attach to cytoskeleton

Interlock cells

Provide channels Between cells

Basement membrane Holds epithelium to rest of bodyProteins and glycoproteins from basal lamina and reticular lamina

Epithelium continuously replaced by stem cells near basement layer

Epithelium classificationSimple epithelial tissue = single layer of cells

Stratified epithelial tissue = stacked cells

Cell shapes Squamous cuboidal columnar

FlatIrregular shapeLining ventral body cavityMouthKidney tubulesBlood vesselsWhere thin/permeable required

Box shapedDuctsglands

Long and narrow(simple only)Secretion absorptionCilia and microvilliSmall intestineNasal cavity

Epithelium and glands

Endocrine glands = to follow

Exocrine glands = secrete into ducts

Merocrine = secretion via exocytosismucous

Apocrine = secretion with loss of cytoplasmmilk

Holocrine = secretion with loss of cellsebum

Epithelial secretions

Serous secretion = watery with enzymesparotid salivary glands

Mucous secretions = watery with glycoproteinsfor lubricationsublingual salivary glands

Mixed secretion = bothsubmandibular salivary glands

Connective tissueConnect, support, transport

Bone, fat, blood

Characteristics

With specialized cells

With extracellular proteins

With ground substance

Proteins + ground substance = extracellular matrix

Connective tissue

Functions Structural framework

Transport (fluids)

Protection (cushion)

Support/connect tissues

Store energy

Defense

Connective tissue classification

Connective tissue proper

Fluid connective tissue

Supporting connective tissue

Cellular and matrix content variedAdipose, tendonsMay be loose or dense

Distinct cells in watery matrixBlood, lymph

Cartilage, bone

Connective tissue PROPERThe CELLS

Fibroblasts

Macrophages

Adipocytes

Mesenchymal cells

Melanocytes

Mast cells

Lymphocytes

Microphages

Always present, secrete hyaluronan to make ground substance, viscous

WBCs that engulf pathogens

Fat cells

Stem cells that produce macrophages,fibroblasts and other connective tissue cells

Synthesize/store pigment

Release histamine and heparin in response to injury

WBCs involved in immune response

WBCs involved in protection from pathogens

Connective tissue PROPER

The FIBERS

Collagen

Reticular fibers

Elastin fibers

Long, straight, unbranchedtendons, ligaments

Like collagen but branchedStabilize position of cells

Thin, branchedReturn to original shape

The GROUND SUBSTANCE

Clear, colorless, viscous

Loose connective tissue

Adipose, reticular

Dense connective tissue

Tendons, ligaments, surrounding organs

FLUID connective tissueBlood Lymph

Erythrocytes (RBCs)

Leukocytes (WBCs)

Platelets

Plasma

Hemoglobin~45% blood volume

Immune system

Blood clotting

Watery matrix

Lymphocytes

Interstitial fluid

Immune system

Watery matrix collected from surrounding cells

SUPPORTING connective tissue

Cartilage Chondrocytes produce matrixAvascularPerichondrium separates cartliage from other tissue

Types of cartilage

Hyaline Elastic Fibrocartilage

CommonTightly packed

collagenRibs, sternumNasal, end bones

Elastic fibersEpiglottis,Middle ear,Pinna, larynx

Interwoven collagenDurableSpinal vertabraePelvic bones

SUPPORTING connective tissue

Bone Osseous tissueOsteocytes in matrix with calcium saltsCovered by periosteum

More to follow with skeletal system

Connective tissueMembranes

Mucous membranes

Line cavities that communicate with exteriorRespiratory, digestive, urinary, reproductive

Serous membranesLine divisions in ventral body cavityPleural = pleural cavityPeritoneum = peritoneal cavityPericardium = pericardial cavity Transudate = fluid on surface of serous membranes

Connective tissueMembranes

Cutaneous membrane

= skin = covers surface of body

Synovial membranes

Capsule at articulations (joints)Loose collagen, proteoglycans, glycoproteinsFull of synovial fluid

Connective tissue layers

Superficial fascia

Deep fascia

Subserous fascia

Subcutaneous/hypodermisSkin/underlying organs

Deep connective tissueOrgans/muscle

Between serous membrane and deep fascia

Muscle tissueFor MOVEMENT via contraction

3 types of muscle tissue

Skeletal muscle

Cardiac muscle

Smooth muscle

Striated, multi nucleatedvoluntary movement

Heartconnected at intercalated discs

NonstriatedInvoluntary movement

MORE TO FOLLOWMuscular system

Neural tissue

Conduct electrical impulses

Neurons = conduct nerve impulsesGlial cells = support neurons

MORE TO FOLLOW Nervous system

Embryology Zygote undergoes cleavage morula

BLASTULA (blastocyst) = hollow ball

Gastrulation forms 3 germ layers

Ectoderm, mesoderm, endoderm

Become different tissues organ systems (page 1088-1089)