Histology The study of tissues. Homeostasis Maintenance of a constant internal environment. We Don’t Like Stress. Physiology identifies and studies the.

HistologyThe study of tissues

Homeostasis

• Maintenance of a constant internal environment.

• We Don’t Like Stress.

• Physiology identifies and studies the mechanisms of homeostasis.

• Controlled by Two Systems– A.– B.

Levels of Organization

Cells

Tissues

organs

organ system

organism

Tissuesgroups of cells with a common structure and function

Four categories

epithelial

connective

muscle

nervous

Epithelial tissuelocation: outside of body, line organs and cavities

Function: barrier, absorption or secretion– Glandular secretory portion of gland

2 types

simple - one layer

stratified - multiple layers

“pseudostratified” appears stratified due to cells of various lengths

Epithelial tissueCell Shapes

squamous - floor tiles

cuboidal - dice

columnar - bricks on end

Simple SquamousLeaky to allow diffusion/osmosis.

Capillaries, alveoli.

May be keratinized on body surfaces.

Connective Tissue

Basement Membrane

Stratified Squamous

Connective Tissue

Readily sloughed off.

Skin, anus, vagina.

Simple Cuboidal

Area of secretion or absorption.

Stratified Cubiodal

Simple Columnar

Ciliated Columnar

Lumen of vessel

High secretion and absorption, High SA/VOL

Pseudostratified ColumnarPseudostratified Ciliated Columnar

Some cells do not reach the surface

Connective TissueMOST ABUNDANT TYPE OF TISSUE.

binds and supports other tissues, TRANSPORT, FRAMEWORK, STORE ENERGY

cells create a matrix/ web of fibers [Matrix non-living web of fibers.]

3 kinds of fibers

collagenous fiber - made of collagen

Elastic fibers - Elastin Protein

reticular fibers - Thin collagen fibers

Types connective tissueloose connective binds epithelia to underlying tissue; holds organs

1-Fibroblasts- secretes extracellular proteins

2-Macrophages- amoeboid WBC’s; phagocytosis

3-Adipose tissue- fat storage; insulation

Types of Connective Tissuefibrous connective - parallel Bundles of cells

Ligaments, Tendons,

cartilage - collagen in rubbery matrix

bone - mineralized tissue

blood - liquid plasma matrix

Collagen

Tough, somewhat flexible protein. Provides the toughness of meats.

Very strong, resists longitudinal stress (tensile strength). Underlies epithelial tissue.

Elastic fibersLong threads of elastin.

Easily returns to original shape (rubberband). This is from an aorta. Also found in skin and lungs.

Small, unbranched.

Secreted by fibroblasts.

Nuclei of Fibroblast

Loose Connective Tissue (areolar)

• Loose web of fibers (all 3)

• Fills space between organs (Styrofoam peanuts). Gel-like matrix.

• Composed of elastin (elasticity), collagen (strength), reticular fibers (support/form).

• Edema: excess interstitial fluid absorbed by LCT

Dense Connective tissue

Tendon Fibrous Connective Tissue.

Bundles of collagenous fibers. Secreted by fibroblasts.

Non-elastic. Resists pulling forces

Fxn: strong attachment between structures (tendons & ligaments)

Nuclei of Fibroblast

CartilageHyaline

Elastic cartilage

Chondrocyte

Large amount of collagen, embedded in chondroitin sulfate.

Provide rigid support. Nose, ear, trachea, interverterbral disks.

Reduces friction on ends of long bones, absorbs shock

Blood

Eosinophil

Neutrophil

Connective tissue with liquid matrix (plasma). Two types of cells RBC’s (Erythrocytes) and WBC’s (Leukocytes)

Plasma composed of H2O, NaCl, plasma proteins

R.B.C’s

W.B.C.

Adipose (FAT)

Nucleus

Adipocyte

15% Male body wt.

22% Female body wt.

Bone

Osteocytes

Haversian System/ Canal

Support, protection, storage, movement.

Osteocytes produce collagen + calcium phosphate hydroxyapatite

Muscle Tissuelong cells called muscle fibers capable of contracting when stimulated

3 types

Smooth - involuntary

Skeletal - voluntary

cardiac - walls of heart

MuscleSkeletal Muscle Cardiac Muscle

Fxn: Motion, Heat production, maintain posture.

Highly specialized for contraction

Aka. VoluntaryStriated, branched.

Intercalated disks to speed impulse.

Smooth Muscleaka: visceral, unstriated.

Surround hollow structures (stomach, blood vessels, intestine, bladder.

Nervous tissue

neuron or nerve cell

specialized to transmit nerve impulses

Dendrites: transmit impulses from tips to rest of neuron

Axons: transmit impulses toward another neuron or effector

Neuron and Glial Cells

Nervous Tissue

Neuromuscular Junction

Create a presentation: use microscope pictures

Show the All types of epithelial: simple squamous, simple cuboidal, stratified squamous, simple columnar

tell what they are where they would be located

SHow types of connective tissue and what they do:

adipose, cartilage, loose connective, ground bone (no longer a ground bone slide)

show the 3 kinds of muscle tissue and how to tell them apart:

Skeletal, cardiac, smooth

Show a neuron - what are the axons and dendrites? - Use a web picture

Organ systems

Organ: organization of tissues

Mesentaries: suspension of organs (connective tissue)

Thoracic cavity (lungs and heart)

Abdominal cavity (intestines)

Diaphragm (respiration)

Organ systems…...

Digestive-food processing

Circulatory-internal distribution

Respiratory-gas exchange

Immune/Lymphatic-defense

Excretory-waste disposal; osmoregulation

Endocrine-coordination of body activities

Reproductive-reproduction

Nervous-detection of stimuli

Integumentary-protection

Skeletal-support; protection

Muscular-movement; locomotion

Regulation of Internal Environment

Interstitial fluid: internal environment of vertebrates; exchanges nutrients and wastes

Homeostasis: “steady state” or internal balance

Negative feedback: change in a physiological variable that is being monitored

response counteracts the initial fluctuation;

i.e., body temperature

i.e., uterine contractions at childbirth

Positive Feedback

Positive feedback: physiological control mechanism in which a change triggers mechanisms that amplify the change;

Metabolism: sum of all energy-requiring biochemical reactions

Size vs. Metabolic Rate

Inverse relationship

Small = high metabolic rate

Large = low metabolic rate

Endotherms: bodies warmed by metabolic heat

Ectotherms: bodies warmed by environment

Basal Metabolic Rate (BMR): minimal rate powering basic functions of life (endotherms)

Standard Metabolic Rate (SMR): minimal rate powering basic functions of life (ectotherms)

Countercurrent exchange

Counter Current -Common process in multiple systems

Heat exchange example