Anatomy & Physiology Unit 2

tissue

a group of cells with similar structure and function

histology

the study of tissues

extracellular matrix

complex network of fibrous proteins and ground substance that surrounds cells, providing both structural support and biochemical regulation to tissues

4 primary types of tissues

epithelial, connective, nervous, muscular

characteristics of epithelial tissues

cells are close together, little to no extracellular matrix, form most glands, free surface (may contain microvilli, cilia, and flagella), no blood vessels, basement membrane

function of epithelial tissues

protect, act as a barrier, diffusion & filtration, secretion, absorption

how are epithelial cells named?

number of cell layers and shape

simple squamous

structure: 1 layer of flat, tile like cells

function: diffusion, filtration, osmosis

location: lungs, kidneys, blood vessel

stratified squamous

structure: many layers of flat, tile like cells

function: protect and act as a barrier

location: mouth, throat, esophagus, skin

simple cuboidal

structure: 1 layer of square shaped cells

function: absorption and secretion

location: glands, small intestines, kidneys

simple columnar

structure: 1 layer of tall, narrow cells

function: secrete mucus and absorption

location: stomach, intestines, uterine tubes, respiratory tract

pseudostratified columnar

structure: appears stratified but isn’t, cilia on top

function: secrete music and propel debris out of respiratory tract

location: nasal cavity, trachea

transitional

structure: changes shape, stretched = squamous, not stretched = cuboidal (depending on how full bladder is)

function: hold fluids

location: urinary bladder

microvilli

increase cell surface area (shorter than cilia)

cilia

move materials across cell surfaces (short and numerous)

flagella

move sperm cells (longer than cilia, 1-2 per cell)

basement membrane

attaches epithelial cells to underlying tissue

characteristics of connective tissue

cells are far apart, large amounts of extracellular matrix, abundance of blood vessels

function of connective tissue

enclose and separate, connect, support and movement, storage, cushion and insulation, transport, protect

components of extracellular matrix

fluid, ground substance (sugar & protein), protein fibers

characteristics of extracellular matrix

located between cells; support, connect, and communicate with cells

how are connective tissues classified?

based on the type of extracellular matrix & function

loose CT

location: between organs, muscles, glands, skin

structure: loose network of collagen and elastic fibers (has clear spaces)

function: support and protect

reticular CT

location: spleen, lymph nodes, thymus gland

structure: loose network of reticular fibers, has bigger fibers than loose

function: supportive framework of lymphatic organs

adipose CT

location: under skin and around organs

structure: collagen and elastic fibers, cells (adipocytes) with lipids, little white clouds representing the cell

function: storage, insulate, cushion

dense regular CT

location: tendons, ligaments, vocal cords

structure: densely packed collagen fibers running in parallel directions

function: connect and can withstand pulling forces

dense irregular CT

location: dermis

structure: densely packed collagen fibers running in random directions

function: resist tearing

hyaline cartilage

location: covers the ends of bones and trachea

structure: some collagen fibers

function: reduces friction (cushions)

fibrocartilage

location: between vertebrae

structure: lots of collagen fibers

function: can withstand compressions

elastic cartilage

location: ear

structure: elastic fiber

function: can recoil

compact bone

location: outer layer of all bones

structure: dense and solid, made of osteons arranged in tightly packed layers

function: strength, support, protection

spongy bone

location: inside bones

structure: porous, lightweight network of trabeculae (thin bony plates); does not contain typical osteons

function: makes bones lighter while maintaining strength, contains red bone marrow for blood cell production

blood

liquid connective tissue composed of erythrocytes, leukocytes, and platelets

location: cardiovascular system but flows to every part of the body function: transports nutrients, oxygen, waste, and hormones

nervous tissue

structure: consists of neuron (nerve cell) & neuroglia (supporting cells); includes dendrites, cell bodies, and axons

location: brain, spinal cord, and peripheral nerves

function: controls and coordinates body movements

skeletal muscle tissue

structure: long and cylindrical

location: attached to bones

number of nucleus/nuclei: many

location of nucleus/nuclei: periphery

striated: yes

type of control: voluntary

cardiac muscle tissue

structure: web shaped

location: heart

number of nucleus/nuclei: one

location of nucleus/nuclei: center

striated: yes, contains intercalated disks

type of control: involuntary

smooth muscle tissue

structure: spindly shaped, not parallel

location: organs and glands

number of nucleus/nuclei: one

location of nucleus/nuclei: center

striated: no

type of control: involuntary

tissue growth

cells increase in number or size

tissue repair

substitute dead cells for viable cells

tissue regeneration

cells of same type are developed and no scarring occurs

tissue replacement

cells of a different type develop and scarring occurs

tissue death (necrosis)

dead tissue due to trauma, toxins, or infection