ANAT Ch 4 Tissues BULK

BULK of info from textbook

the body contains at least ____ distinct _____

200 cell types

cells contain essentially same internal structures yet vary in

shape and function

different types of cells not randomly distributed throughout body, but rather

occur in organized layers (tissue)

summary single cell > human body

single cell at fertilization > divides to trillions each built from same blueprint > organize into tissues + become irreversibly committed to developmental pathway

TISSUE

group of cells found tgt in body

share common embryonic origin, morphological features

arranged in orderly pattern achieve function

tissues appear in more complex organisms, not

multicell protists, ancient euks

4 broad categories of tissues

epithelial

connective

muscle

nervous

each of 4 categ of tissues characterized by

specific functions > overall health and maintenance of body

disruption in structure is sign of

injury/disease

changes in tissues detected by

histology

histology is micro study of

tissue appearance, organization, function

Epithelial Tissue

aka epithelium

sheets of cells cover exterior surfaces of body

line internal cavities + passageways

form certain glands

Connective Tissue

binds cells + organs

protect, support, integrate all parts of body

Muscle Tissue

is excitable

responds to stimulation, contract for movement

3 major types

• skeletal/voluntary

• smooth

• cardiac

Nervous Tissue

is excitable

allows propagation electrochem signals (nerve impulses) communicate diff regions body

zygote

aka fertilized egg

single cell formed by fusion of egg and sperm

after fertilization zygote gives rise

rapid mitotic cycles > many cells: embryo

first embryonic cells generated have ability to

differentiate into any type of cell

aka called totipotent

totipotent

each has capacity to divide, differentiate, develop into new organism

as cell proliferation progresses, 3

major cell lineages established within embryo

each of these lineages of embryonic cells forms the

distinct germ layers from which all tissues/organs eventually form

each germ layer is identified by its relative ____

ectoderm

mesoderm

endoderm

position

ecto - outer

meso - middle

endo - inner

epithelial tissue originates in

all three layers

nervous tissue derives primarily from

ectoderm

muscle tissue derives primarily from

mesoderm

Tissue Membrane

thin layer/sheet of cells covers

outside of body,

organs,

internal passageways that lead to exterior of body,

lining of moveable joint cavities

2 types of basic tissue membranes

connective tissue

epithelial membranes

connective tissue membrane formed solely from

connective tissue

connective tissue membranes

encapsulate organs

line movable joints

synovial membrane

type of connective tissue membrane lines cavity of freely movable joint

ex: shoulder, elbow, knee

fibroblasts in inner layer of synovial membrane release

hyaluronan into joint cavity

hyaluronan effectively

traps available water > synovial fluid

synovial fluid

natural lubricant enables bones of joint move freely against another without much friction

readily exchanges water + nutrients w blood (like all body fluids)

epithelial membrane composed of

epithelium attached to layer of connective tissue

ex: skin

mucous membrane

also composite of connective + epithelial tissues

sometimes called mucosae these epithelial membranes

line body cavities + hollow passageways that open to external environment

includes: digestive, respiratory, excretory, reproductive tracts

mucus is produced by

the epithelial exocrine glands

mucus covers the

epithelial layer

lamina propria

“own layer”

underlying connective tissue

helps support fragile epithelial layer

serous membrane

epithelial membrane composed of mesoderm-derived epithelium (mesothelium)

supported by connective tissue

serous membranes line

coelomic cavities of body (those don’t open to outside)

covers organs within those cavities

serous membranes are essentially

membranous bags w mesothelium lining inside and connective tissue on outside

serous fluid secreted by cells of thin squamous mesothelium

lubricates membrane

reduces abrasion, friction between organs

serous membranes identified according to

locations

3 serous membranes line

thoracic cavity

2 pleura cover the

lungs

pericardium covers

heart

4th: peritoneum

serous membrane in abdom cavity covers abdom organs +

forms double sheets of mesenteries suspend many digestive organs

skin is an epithelial membrane also called

cutaneous membrane

cutaneous membrane is a

stratified squamous epithelial membrane resting on top of connective tissue

apical surface of cutaneous membrane

exposed to external environment, covered w dead, keratinized cells

help protect body from desiccation and pathogens

epithelium forms much of the _____ tissue of the body

glandular

areas exposed to the outside

skin, airways, digestive tract, urinary, reproductive systems

all lined by an epithelium

endothelium is a type of

epithelium

hollow organs and body cavities that don’t connect to exterior of body (including blood vessels, serous membranes) are lined by

endothelium

all epithelia share important structural and functional features

tissue is highly cellular, little/no extracell material present between cells

cell junction created by

adjoining cells form specialized intercellular connection between cell membranes

epithelial cells exhibit polarity with differences in structure and function between

exposed/apical facing surface

and

basal surface close to underlying body structures

basal lamina

mixture of glycoproteins and collagen

basal lamina provides

an attachment site for epithelium

separating it from underlying connective tissue

basal lamina attaches to

reticular lamina

reticular lamina secreted by

underlying connective tissue

basal lamina + reticular lamina forms

basement membrane helps hold it all tgt

epithelial tissues are nearly completely

avascular (few/no blood vessels)

no blood vessels cross basement membrane to

enter tissue

if avascular, nutrients must come by

diffusion or absorption from underlying tissues/surface

many epithelial tissues are capable of rapidly

replacing damaged/dead cells

sloughing off of damaged/dead cells is characteristic of

surface epithelium

sloughing off of damaged/dead cells allows

our airways, digestive tract rapidly replace damaged with new cells

epithelial tissues provide body’s first line of protection from

physical, chemical, biological wear and tear

cells of an epithelium act as gatekeepers

controlling permeability, allow selective transfer of materials across physical barrier

all substances that enter body must cross an epith.

many epith. cells capable of secretion and

release mucous and specific chem compounds onto their apical surfaces

ex: epith of small intestine release digestive enzymes

a glandular epithelium contains many

secretory cells

epithelial cells are typically characterized by

the polarized distribution of organelles and membrane bound proteins between their basal and apical surfaces

certain organelles are segregated to basal sides whereas other

organelles/extensions are on apical surface

ex: cilia, when present

cilia

microscopic extensions on apical cell membrane supported by microtubules

beat in unison, move fluids and trapped particles

ciliated epith lines ventricles of brain where it

helps circulate cerebrospinal fluid

ciliated epith in airway forms

mucociliary escalator (upward towards the throat)

nasal cilia

sweep mucous down towards throat

both cases airway and nasal, transported materials usually

swallowed, end up in acidic envir of stomach

cells of epithelia are

closely connected, not separated by intracellular material

3 basic types of connections allow varying degrees of interaction btwn cells:

• tight junctions

• anchoring junctions

• gap junctions