Chapter 3- Tissues Flashcards
what is a tissue
- group of cells performing a similar function
- study is called histology
- composed of 75 trillion cells
variations of tissues
-vary in structure, function, and content of extracellular matrix
tissue types
- epithelial
- muscle
- nervous
- connective
extracellular matrix
- located outside the cell
- a substance produced by cells of a tissue which can contain protein fibre, salts, water, and dissolved macromolecules
where is epithelial tissue
- lines every body surface and cavities
- lines inside and outside of organs
- derives majority of glands
- has little to no extracellular matrix
- on basement membrane
- avascular
epithelial tissue functions
- physical protection
- selective permeability
- secretions
- sensations
epithelial physical protection
- protection from dehydration and abrasions
- protection from physical, chemical, and biological agents
- regenerations
epithelial selective permeability
regulates passage of certain molecules in or out of a certain region of body
epithelial secretions
exocrine cells produce secretions such as sweat or oil
epithelial sensation
posses nerve endings that detect light, taste, sound, smell, and hearing
epithelial classification
2 criteria:
1) number of layers of cells
2) shape (morphology) of the cells
epithelial cell layers
- simple
- stratified
- pseudostratified
simple epithelium
- single layer of cells
- all cells having an apical surface attached to basement membrane
stratified epithelium
- 2 or more layers of cells
- not all cells have an apical surface not attach to basement membrane
pseudostratified epithelium
- single layer but not all cells reach apical surface
- nuclei give appearance of multilayered, stratified epithelium but they are not
epithelial cell morphology
- squamous
- cuboidal
- columnar
- transitional
squamous epithelium morphology
flattened and similar to shape of fried egg
cuboidal epithelium morphology
same size on all sides, nucleus is central
columnar epithelial morphology
taller than they are wide, nucleus is oval and in basal region
transitional epithelial morphology
a mixture of squamous, cuboidal, and columnar
how to decide epithelial type
- start with single layer simple
- then consider multiple layered stratified
epithelium types
- simple squamous
- simple cuboidal
- simple columnar
- pseudostratified columnar
- stratified squamous
- transitional
- ciliated
glands
- perform secretory functions
- produce mucin, hormones, enzymes, and waste products
- unicellular or multicellular
categories of glands
- endocrine glands
- exocrine glands
endocrine glands
- do not have ducts
- secrete directly into interstitial fluid or bloodstream
- derived from multiple tissues
exocrine glands
- have ducts
- secrete products into their ducts
- derived from epithelial tissue
muscle tissue
- comprised of cells called fibres
- fibers contract when stimulated
muscle tissue function
- contraction of fibres results in movement
- myofilaments (actin & myosin) are responsible for muscles contractibility
types of muscle tissue
1) skeletal
2) cardiac
3) smooth
skeletal muscles
- attached to bones and some skin
- contraction causes movement of skeleton or skin
cells of skeletal muscles
- cylindrical and long
- multinucleated
- striated (striped)
- voluntary*
cardiac muscles
- on walls of heart (myocardium)
- contactions cause movement of blood
cells of cardiac muscles
- branched
- y-shaped
- shorter than skeletal fibre cells
- striated
- involuntary
- attach end to end by strong gap junctions called intercalated discs that allow rapid passage of electoral currents from one cell to the next during each heart beat called intercalated discs
smooth muscles
- in walls of most internal organs
- contraction causes movement of food, air, blood, oocytes, and sperm
- slow but consistent movement
cells of smooth muscles
- relatively short
- wide in middle
- tapered at ends (fusiform)
- non-striated
- involuntary
nervous tissue
2 types of cell:
1) neurons
2) neuroglia
nervous tissue function
communication and control of body functions
neurons
- functional unit of nervous system
- nerve cells that initiate and conduct electrical activity through body
- produce action potentials
neuroglia
- cells that support neurons
- half the volume of CNS, 50x more numerous
- help protect and nourish the neuron cell
- cells can divide (tumour formation) not excitable
neuron structure
cell body: -single nucleus with prominent nucleoli -nissl bodies (RER) neurofilaments give cel shape and support microtubules move materials inside cell cell process: -dendrites -axons
dendrites
- impulse into cell
- conducts impulse towards cell body
- short, highly branched, unmyelinated
- surfaces specialized for contact with other neutrons
- has neurofibers and nissl bodies
axons
- impulse out of cell
- conducts impulse away from cell body
- long, thin, cylindrical process of cell
- arises at axon hillock
- side branches end in fine process called axon terminals
- swollen tips contain vesicles filled with neurotransmitters
neuroglia cell types
CNS: astrocytes oligodendrocytes microglia ependymal PNS: Schwann cells satellite cells
connective tissue
- most diverse, abundant, widely distributed, and structurally varied of all tissues
- connective tissue= cells + extracellular matrix
- extracellular matrix= fibers + ground substance
- tendons, ligament, body fat, blood, bones, and cartilage
- the “glue” and “filler” of body
connective tissue function (7)
- connect and support body structures
- physical protection
- support and structural framework
- binding of structures
- storage
- transport
- immune protection
connective tissue classification
- CT proper
- supporting CT
- fluid CT
cells of connective tissue proper
1) resident cells
2) wandering cells
resident CT cells
- DONT MOVE
- fibroblasts
- adipocytes
- fixed macrophages
- mesenchymal cells
wandering CT cells
- MOVE
- mast and plasma cells
- free macrophages
- leukocytes
fibres of connective tissue
produced by CT cells and secreted into extracellular matrix
1) collagen fibers
2) elastic fibers
3) reticular fibers
CT collagen fibers
- 70% of CT fibres
- long thick, unbranching, strong, flexible, and resistant to stretching
- collagen makes up 25% of protein in body, most abundant protein
CT elastic fibers
- thinner than collagen, stretch easily, branch, and rejoin
- allow structures like blood vessels to stretch and relax
CT reticular fibers
- thinner than collagen fibres
- form a meshwork-like configuration
- found in organs with abundant spaces and acts as packing material
CT ground substance
- combo of proteins and carbohydrates
- additional content like water and salts can result in semi-fluid texture (adipose, fat) or hard texture (bone)
CT proper categories
- loose CT: fewer protein fibres and more ground substance
- dense CT: more protein fibres and less ground substance
Loose CT types
serves as body packing material, found in spaces around organs
1) areolar CT
2) adipose CT
3) reticular CT
areolar CT
- has fibroblasts, collagen, and elastic fibers
- can be distorted without damage
- found subcutaneous to skin
adipose CT
- known as “fat”
- comprised of adipocytes (fat cells) and very little else
- cells are connected but not strongly adhered to each other
reticular CT
- contains reticular fibers, fibroblasts, and leukocytes
- found in spleen lymph nodes, and bone marrow
dense CT types
- strong, has fibres (mostly collagen) packed tightly together
1) dense regular CT
2) dense irregular CT
3) elastic CT
dense regular CT
- collagen fibres aligned parallel to applied force
- found in tendons (muscle to bone) and ligaments (bone to bone)
dense irregular CT
- bundles of collagen extending in different directions
- in deep portion of skin (dermis) and capsules around organs (liver, kidney, spleen)
elastic CT
- elastic fibres provide ability to stretch and recoil
- in vocal cords and large/medium arteries
specialized CT
supporting CT: -cartilage -bone Fluid CT: -blood
cartilage tissue types
1) hyaline cartilage
2) elastic cartilage
3) firbocartilage
cartilage tissue cells
- chondroblasts found growing in cartilage
- chondrocytes
cartilage tissue matrix
- gel-like ground substance
- fibers: collagen, elastic fibers in some
cartilage tissue general features
- resists compression due to large amounts of water in matrix
- functions to cushion and support body structures
bone tissue types
1) compact bone
2) spongy bone
bone tissue cells
- osteoblasts
- osteoclasts
bone tissue matrix
- gel-like ground substance calcified with inorganic salts
- fibers: collagen
bone tissue general features
- hard tissue that resists compression and tension
- functions in support
fluid connective tissue
- plasma: watery ground substance containing protein fibres
- erythrocytes: red blood cells
- leukocytes: white blood cells
- platelets: fragments of blood cells involved in blood clotting
