Physiology 1, Fall 2008, LPC

Chapter 3 - Compartmentation: Cells and Tissues

Three major body cavities (Anatomic)

1. Cranial

2. Thoracic

3.Abdominopelvic

Three fluid compartments (Functional)

1. Intracellular fluid

2. Extracellular fluid

Interstitial fluid

Plasma

Biological Membranes

Cell Membrane = Plasma membrane

Functions

1. Physical isolation

2. Regulation of exchange with the environment

3. Communication between the cell and its environment

4. Structural support

Composition

Phospholipid bilayer with proteins and carbohydrates inserted in surface

phosphate end - hydrophilic, faces aqueous environment in interstitial and cellular fluid

lipids, hydrophobic, face each other

proteins can control entry & exit of substances

carbohydrates - protective layer or identification

fluid mosaic model - proteins & carbohydrates move around in cell surface to where needed

Proteins

Integral or transmembrane - alpha helix winds back & forth through membrane, has extra- & intra- cellular ends

Peripheral - anchored to cell surface, enzymes & some structural binding

 

Intracellular Compartments

Plasma membrane encloses cytoplasm with nucleus, membranous organelles & inclusions

Inclusions - ribosomes, proteosomes (degrade proteins), cytoskeleton, centrioles, cilia, flagella

3 types of cytoplasmic protein fibers - structural support & movement

microtubules - centrioles, cilia, flagellum

Cytoskeleton assembled & disassembled as needed

1. mechanical strength & shape

2. help organize cell interior

3. intracellular transport

4. connect with extracellular proteins - bind tissues together, communicate

5. movement

Motor proteins

myosin in muscle binds to actin

kinesins & dyneins bind to cytoskeleton & "walk" load

Organelles

Mitochondria

Endoplasmic reticulum - smooth & rough

Golgi

Cytoplasmic vesicles

storage (glycogen)

secretory - substances for export

lysosomes & peroxisomes - clean up

Nucleus

nuclear pores in nuclear membrane- control what comes into & out of nucleus

chromatin = DNA + associated proteins

Tissues

Extracellular matrix - extensive in connective tissues

structure, strength, communication between cells

Cell Junctions - tight junction, desmosome, gap junction

Epithelial

Structure - one or more layers stuck on basal lamina. Variably tightly stuck to each other.

simple = 1 layer, stratified = multiple layers

shapes - squamous, cuboidal, columnar

Functions:

1. exchange - thin flat cells

2. transporting - 1 cell thick, cuboidal or columnar, microvilli, fairly tight cell junctions, high energy requirement -> many mitochondria

3. ciliated - 1 cell thick, respiratory system, female reproductive tract

4. protective - many cells thick, tightly connected, protect areas from abrasion & chemicals, separate in from out

5. secretory - make, then export substances

a. exocrine have ducts to surface - secrete watery or mucous

b. endocrine separated from surface - secrete hormones

Connective

-> shape and support

characterized by much extracellular matrix

 

Muscle & Nervous Tissues - discussed in other chapters

 

Tissue Remodeling

Apoptosis - programmed cell death. Remodeling and clean-up

Stem cells - retain ability to divide. Varying degrees of plasticity.