tissues (cont) Flashcards
tissue
group of similar cells and extracellular products that
perform a common function
Four types of tissue in the body
- Epithelial tissue
- Connective tissue
- Muscle tissue
- Nervous tissue
Characteristics of Epithelia
- polarity
- innervation
- avascularity
- regeneration
polarity of epithelia include
apical and basal surfaces
what type of tissue in basement membrane?
connective tissue
Functions of Epithelial Tissue
- Provide Physical Protection
- Control Permeability
- Provide Sensation
- Produce Specialized Secretions (glandular epithelium
what is intercellular connection within epithelium (ET)?
cell junctions
Cell junctions
Form bonds with other cells or extracellular material
types of cell junctions
- Tight junctions
- Gap junctions
- Desmosomes
Tight junctions
– Water tight seal
– Prevents solutes from moving between cells
Gap Junctions
– Allow rapid communication
– Are held together by channel proteins (junctional
proteins, connexons)
– Allow ions to pass
Desmosomes
CAMs, dense areas, and intercellular cement
2 types of desmosomes
- spot desmosomes
- hemidesmosomes
Spot desmosomes
- Tie cells together – like a button
– Allow bending and twisting
Hemidesmosomes
Attach cells to the basal lamina
2 types of basement membrane
- Secreted by epithelia = basal lamina
- Secreted by connective tissue
2 types of basal lamina
- lamina lucida: thin layer (clear layer)
- lamina densa: type IV collagen (dense layer)
basement membrane secreted by connective tissue
lamina recticularis (recticular layer)
-> type III collagen (aka reticular fibers)
how do epithelia maintain and repair?
Epithelia are replaced by division of germinative cells
(stem cells)
singular of ET
epithelium
plural of ET
epithelia
2 ways to classify epithelia
- based on shape
- based on layers
classes of epithelia based on shape
- squamous epithelia
- cuboidal epithelia
- columnar epithelia
which type of epithelia that is thin and flat?
squamous epithelia
which type of epithelia is square shape?
cuboidal epithelia
which type of epithilia is tall, slender rectangle?
columnar epithelia
types of epithelia based on layers
- simple epithelium: single layers of cells
- stratified epithelium: several layers of cells
subtypes of squamous epithelia
- simple squamous epithelium
- mesothelium
- endothelium
- stratified squamous epithelium
Mesothelium
Lines body cavities
Endothelium
Lines heart and blood vessels
types of glandular epithelia
- endocrine glands
- exocrine glands
endocrine vs exocrine glands
- endocrine glands: release hormones, no ducts
- exocrine glands: produce secretions onto epithelial surfaces through ducts
types of glandular secretion
- merocrine secretion
- apocrine secretion
- holocrine secretion
merocrine secretion
- Released by vesicles (exocytosis)
- Salivary glands
apocrine secretion
- Released by shedding cytoplasm (more destructive)
- Mammary glands
Holocrine Secretion
- Product builds up in cell causing it to swell
- Released when cell ruptures
how to distinguish connective tissues?
based on:
- types of specialized cells
- extracellular matrix composition
Extracellular matrix composition
- protein fibers (aka CT fiber) (solid): elastic, collagen, recticular
- ground substance (liquid): water, electrolytes, etc
collagen fibers (type I)
- most common
- long, straight, unbranched
- resist force in one direction
ex: tendons, ligaments
reticular fiber (type III collagen)
- network of fibers
- Resists force in many directions
ex: Sheaths around organs
elastic fibers
– Contain elastin
– Branched and wavy
– Return to original length after stretching
– Elastic ligaments of vertebrae
Functions of Connective Tissue
– Structural framework for the body
– Transport of fluids and dissolved materials
– Protect organs
– Support/surround, and interconnect other tissues
– Storage of energy reserves
– Defense from invading microorganisms
subtypes of connective tissues proper
-loose connective tissues: areolar, adipose, reticular
- dense connective tissues: regular, irregular, elastic
loose vs dense connective tissues
loose CT: More ground substance, fewer fibers
dense CT: More fibers, less ground substance
tendons
attach muscle to bones
ligaments
connect bone to bone and stabilize organs
where does dense irregular CT locate?
- reticular layer of dermis
- Around cartilages (perichondrium)
- Around bones (periosteum)
- Form capsules around some organs (e.g. kidneys)
- Sheaths around nerves
cartilage
- Gel-type ground substance
- For shock absorption and protection
bone
- Calcified (made rigid by calcium salts, minerals)
- For weight support
4 types of membranes
- Mucous membranes
- Serous membranes
- Cutaneous membrane
- Synovial membranes
mucous membrane
epithelial tissue must be moist
serous membrane
has 2 layers:
- parietal layers: cover cavity
- visceral layers: cover organ
3 subtypes of serous membranes
- pleura: cover lungs
- peritoneum: cover abdominal organs
- pericardium: cover heart
cutaneous membrane
– Skin
– Thick, waterproof, and dry
synovial membrane
- produce synovial fluid
- lack a true epithelium
- protect the ends of bones
functions of CT
- Provide strength and stability
- Maintain positions of internal organs
- Provide routes for blood vessels, lymphatic vessels, and
nerves
The body’s framework of connective tissue
fasciae (singular: fascia)
