Chapter 4 Flashcards
(4) basic types of tissues
1) epithelial
2) connective
3) muscular
4) nervous
Epithelial tissues
(4) functions
cover body surfaces
form glands
line hollow organs/cavities/duct
Connective Tissue (3) functions
protect, support & bind organs
Types of CT
Fat - store energy
RBCs, WBCs, platelets
Muscular Tissue
functions (2)
- generate physical force for movement
- generate heat
Nervous tissue
functions (2)
detect changes in body
respond by generating nerve impulses
Tissues of the body develop from?
(3) primary germ layers
(3) primary germ layers
1) endoderm
2) mesoderm
3) ectoderm
Endoderm develops into?
digestive tract, lungs & resp tract, bladder
Mesoderm develops into?
muscles, bones, cartilage, blood vessels, lymph tissue, part of kidneys & gonads
Ectoderm develops into?
nervous tissue, outer skin layer, parts of sense organs, mouth, sinuses & teeth
What tissues are derived from mesoderm?
connective tissue & muscle
What tissues develop from ectoderm?
nervous tissue
Intracellular Junctions
- functions?
connect adjacent cells at specific contact points
Types of Intracellular Junctions (5)
1) tight junctions
2) adherans junctions
3) desmosomes
4) hemidesmosomes
5) gap junctions
1) tight junctions
leak-proof seal bw cells
epithelial tissue of stomach, intestines & bladder
2) adherans junctions
make adhesion belt that keeps tissue from seperating as they stretch & contract
Cadherin glycoprotein inserts into belt-like plaque which is attached to microfilaments of cytoskeleton
3) desmosomes
“spot welds”
- use cadherin
- similar to adherans but plaque attaches to intermediate filaments (keratin) which extend from attachment on 1 side of cell to attachment on another
4) hemidesmosomes
half-welds that join cells to basement membrane
- look like half a desmosome
5) gap junctions
membrane proteins (connexions) form tiny fluid‐filled tunnels (connexons) that allow ions to pass between cells
Epithelial vs. Connective Tissue
Epithelial - more dense, avascular, usually forms layer with underlying & adjacent CT
- high rate of cell division
Why does Epithelial tissue usually form surface layer with underlying & adjacent CT
CT provides blood supply
Why does Epithelial tissue have high rate of cell division?
high rate of turnover - constantly shedding/scraping off skin
(3) major functions of Epithelium
1) selective barrier - limits/assists transfer of substances
2) line surfaces & form barrier
3) secrete mucous, hormones & other substances
Epithelium surfaces (3)
1) Apical
2) Lateral
3) Basal
Apical Surface
faces surface, cavity, lumen or duct
Lateral surface
faces adjacent cells
Basal surface
adher to basement membrane (contains basal & reticular lamina)
Epithelia named according to?
shape
arrangement
Epithelium named according to shape
squamous
cuboidal
columnar
Epithelium named according to arrangement
simple
pseudostratified
stratified
squamous
flat, wide, paving stone cells
cuboidal
cells as tall as they are wide
columnar
cells taller than they are wide
Simple
one layer of cells all in contact with basement membrane
Pseudostratified
all cells contact basement membrane but not all have apical surface
Stratified
2+ layers
only basal layer contacts basement membrane
Transitional cells
cells that change shape
Connective Tissue
most abundant & widely distributed tissue in body
- most heterogeneous of tissue groups
Connective Tissue functions (5)
1) bind tissues together
2) support & strengthen tissue
3) protect & insulate internal organs
4) compartmentalize & transport
5) energy reserves & immune responses
Collagen
main protein in CT & most abundant in body (~25% of total proteins)
Connective Tissue characteristics
highly vascular & supplied with many nerves
- sparse cells
- surrounded by ECM
CT is highly vascular & supplied with many nerves.
Exception?
cartilage & tendon
- little to no blood supply & no nerves
Extracellular Matrix
non-cellular material location between & around cells
ECM consists of?
protein fibers & ground substance (fluid, semifluid, gelatinous or calcified
Importance of the ground substance of the ECM
gives tissues its characteristics - elasticity/flexibility
Cells of Connective Tissue (3)
1) fibroblasts
2) chondroblast
3) osteoblast
1) fibroblasts
most numerous cell of CT
- secrete protein fibers (collagen, elastin & reticular) & ground substance
2) chondroblast
in cartilage
3) osteoblast
in bone
cells ending in “blast”
common immature CT cells
CT cells secrete?
3 common fibers
CT cells secrete (3) common fibers
1) collagen
2) elastin
3) reticular
Relationship between “blast” cells & “cyte” cells
immature blast cells differentiate into mature cyte cells after ECM is produced
“cyte” cells
cells with reduced capability for cell division
(2) major categories of Connective Tissue
1) Embryonic CT
2) Mature CT
Types of Mature CT (5)
1) loose
2) dense
3) cartilage
4) bone
5) liquid
Types of loose CT (3)
1) areolar
2) adipose
3) reticular
Areolar CT
- location, contains & function
loose CT widely distributed in body
- contains several types of cells & all 3 fiber types
- used to attach skin & underlying tissues & as packing between glands/muscles/nerves
Adipose CT
- location & function
loose CT located in subQ layer deep to skin & around organs/joints
- reduces heat loss, serves as padding & energy source
Reticular CT
- function
network of interlacing reticular fibers & cells
- forms stroma (supporting framework) used by cells of lymphoid tissues such as spleen & lymph nodes
types of Dense CT (3)
1) dense irregular
2) dense regular
3) elastic
Dense Irregular CT
- consists of, function
consists mostly of fibroblasts & collagen fibers randomly arranged in sheets
- provides strength when forces pull from many directions
Example of Dense Irregular CT
fascia of muscles & joint capsules
Dense Regular CT
comprise tendons, ligaments & other strong atttachments where strength along 1 axis is needed
(muscle pulling on bone)
Elastic CT
consists of? function?
consists mostly of fibroblasts & freely branching elastic fibers
- allows stretching of certain tissues like elastic arteries (aorta)
Cartilage
tissue with poor blood supply that grows slowly, relatively inactive
- when injured/inflamed, repair is slow
Types of Cartilage (3)
1) Hyaline
2) Fibrocartilage
3) Elastic
Hyaline cartilage
- most abundant
- covers end of long bones & parts of ribs/nose/trachea/bronchi/larynx
- provides smooth surface for joint movement (weak)
Fibrocartilage
very strong tough cartilage with chondrocytes scattered among thick bundles of collagen fibers
- fibrocartilage disks in intervertebral spaces & knee joints support huge loads up/down long axis of body
Elastic Cartilage
chondrocytes located in threadlike network of elastic fibers
- make up malleable part of external ear & epiglottis
How does Cartilage get repaired?
substances & blood cells required for repair must migrate into cartilage (perichondrium)
Growth Of Cartilage - (2) types
1) interstitial - growth from within tissue
2) appositional - growth at outer surface of tissue
Interstitial Growth
chondrocytes rapidly divide & form matrix
- childhood & adolescence
Appositional Growth
cells on inner layer of perichondrium differentiate into chondroblasts & create ECM, causing matrix to deposit on outer surface of cartilage & grow in width
- starts later & continues through adolescence
Bone
CT with calcified intracellular matrix
- work with skeletal muscles to provide movement & protection
- store TAGs, red bone marrow & calcium
Blood & Lymph
atypical liquid CT
Muscle & Nerve Tissues
considered excitable cells because they exhibit electrical excitability
electrical excitability
ability to respond to certain stimuli by producing electrical signals such as action potentials
Action potentials - what do they do?
propagate (travel) along plasma membrane of neuron/muscle due to presence of specific voltage-gated ion channels
Organ
2 tissues combined
Epithelial membranes
- simplest organs in body
- constructed of only epithelium & little bit of CT
= epithelium + CT
types of epithelial membranes (3)
1) mucous membranes
2) serous membranes
3) cutaneous membrane
Mucous membranes
line interior body surfaces open to outside
- (tight junctions between cells, secrete mucus to hydrate, lubricate & trap particles)
Where do you find Mucuous membranes? (3)
1) digestive tract
2) respiratory tract
3) reproductive tract
Serous membranes
line some internal surfaces
Where can you find Serous membranes? (3)
1) parietal layer next to body wall
2) serous fluid b/w layers
3) visceral layer next to organ
Cutaneous Membrane
skin
Synovial membrane
not an organ
- enclose certain joints
- are made of connective tissue only (NO epithelium)
Epithelial Glands - (2) types
1) endocrine
2) exocrine
Endocrine Glands
secrete contents directly into interstitial fluid which diffuses directly into blood (no ducts)
types of Endocrine glands
pituitary
pineal
para/thryoid
adrenal
Exocrine Glands
secrete contents into lumen or duct
- ducts empty onto covering & lining epithelium
types of Exocrine Glands
sweat oil earwax digestive (salivary) pancreas
Parenchyma
constitute functioning part of tissue/organ
Stroma
supporting CT
Parenchyma of Heart
cardiac muscle cells
Stroma of heart
nerves, intrinsic blood vessels & CT
When tissue damage is extensive, return to homeostasis depends on? (2)
active repair of parenchymal cells (if active in repair, tissue regeneration
or stroma (if active, impaired scar tissue will make repair) `
Restoration of an injured tissue/organ to normal structure and function depends entirely on?
whether parenchymal cells are active in repair process.
If parenchymal cells accomplish repair..
tissue regeneration is possible & near-perfect reconstruction may occur
If fibroblasts of stroma are active in repair..
replacement tissue will be new CT
- fibroblasts synthesize collagen & other ECM material to form scar tissue (fibrosis)
Why is the original function of the tissue impaired in scar tissue?
because scar tissue is not specialized to perform functions of parenchymal tissue
Tissue Repair - Epithelium
cells continuously renew
Tissue Repair - Bone
high rate of renewal bc of ample blood suppy
Tissue Repair - - Muscle
poor capacity for renewal bc of slow division of stem cellss
Tissue Repair -Cardiac Muscle
no satellite cells & existing cells dont undergo mitosis
- small # of stem cells may migrate to heart from blood
Tissue Repair - Nervous Tissue
very low capacity for repair
Aging & Tissues
1) healing rate
2) nutritional state
3) thickness of epithelium
4) CT
1) faster in young adults - surgery leaves no scars on fetus
2) better nutritional state, blood supply & higher metabolic rate in young tissues
3) thinner as you age
4) more fragile as you age
