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group of cells similar in structure and function

four basic tissue types

epithelial, connective, muscle, and nervous

epithelial tissue

is a sheet of cells that covers the body surface or lines a body cavity

two types of epithelia

covering and lining and glandular epithelia

covering and lining epithelia

forms the outer layer of the skin
lining in the body cavities
covers the surface of visceral organs


cover the glands of the body

functions of epithelium

protection, absorption, filtration, excretion, secretion, sensory reception

characteristics of epithelial tissues

-composed of tightly packed cells that form a sheet
-cells are connected by tight juntions and desmosomes
-free surface (apical) is exposed to the lumen (opening) of internal organs

basal surface of basement membrane

support of cells
forms boundaries between tissue layers
lie on top of connective tissue


tissue does not contain blood vessels


tissue is supplies with nerve tissues

cell regeneration

through mitosis

simple squamous

single layer, flattened cells, disc shaped central nucliei, sparse cytoplasm.
allows filtration or secretion
air sacs of lungs.

simple cuboidial

single layer of cubelike cells with large spherical central nucliei,
used for secretion and absorption
found in kidney tubules

simple columnar

single layer of tall cells round to oval nucliei
absorption anad secretion of mucous, enzymes and other substances
location: nonciliated type lines most of the digestive tract (stomach to anal canal), gallblader

pseodstratified columnar

single layer of cells differeing hieghts
used in secretion
found in ciliated variety lines the trachea, most of the upper respiratory system

stratified squamous

thick membrane composed of several cell layers, basal cells are cuboidial or columnar and metabollically active , surface cells are flatten
function: protects underlying tissues in areas subjected to abrasion
location: nonkeratinized stype forms the moist linings of the esophagus, mouth and vagina

transitional epithelial

resembles both stratified squamous and stratified cuboidial. surface cells dome shaped or sqamous.
function: stretches readily and permits distention of urinary organ by contained urine.
location: lines the uretus, urinary bladder, and part of the urethra.


is composed of one or more cells that is/are specialized to produce and secrete substance into ducts or body fluids

endocrine glands

ductless and secrete hormones that travel through lymph or blood to target organs

exocrine glands

numerous, many of their products are familar, secrete their product on their body surfaces, or into body cavities.
ex. mucous, sweat, oil, salivary galnds, the pancreas(which synthesizes digestive enzymes)

what three things carry out both exocrine and endocrine functions

pancreas, testes and ovaries

two structural types of exocrine glands

unicellular and multicelluar glands

goblet cells

epithethial cell
-does not have ducts, only ductless exocrine gland in body
- one cell
-secrete mucous to lubricate tissue
found in respiratory, digestive, urinary and reproductive tracts

three types of exocrine glands

merocrine, holocrine, apocrine

merocrine glands

most common,
glands release fluid products by exocytosis
secretion is only produced on demand
-pancreas, salivary and mucous glands

holocrine glands

-secretions accumulate within their cells until they rupture and die
-sebaceous glands

apocrine glands

modified sweat glands
-secretion accumulate at the tip of each cell
- the tips of cells pinch off to release secretion
-rare, remaing part of cell regenerates
-ex. mammary glands

functions connective tissue

- needed for binding structures
-protection, insulation
-fill spaces between tissue
-produce blood cells

characteristics of connective tissue

-derived from embryonic tissue called mesenchyme (stem cell)
-most are highly vascular (rich in blood supply) except cartilage (avascular- no blood supply) and tendons are slightly avascular
-CT cannot be found on free surfaces
-innervated except for cartilage
consist of 3 elements (cells, fibers, no shape(amorphous))
-contains matrix- ground substance+fibers, matrix excreted by cells. Consistency of matrix varies from a liquid to solid

blast cells

-immature cells of Connective tissue (CT)
-blast-spout or produce
-undergo rapid mitosis
-secrete the matrix of CT

types of blast cells

Fibroblast, chondroblast, osteoblast, hemocytoblast


immature cells
-large flat cell with branche processes
-most common type in CT
-secrete fibers into matrix


secrete the matrix of cartilage


secrete the matrix of bones


produce all blood cells

cyte cells

-mature cells of CT
maintain the health or condition of the matrix


-originate as white blood cells
-carries out an immune response
-carry out phagocytosis, clean tissue of bacteria and foreign organisms

mast cells

large cells found near blood vessels
-release heparin and histamine

plasma cells

-small cells that secrete antibodies

collagen fibers

collagen- the most structural protein
-appears as thick and whitish threads
-fibers grouped in a long parallel bundle
flexible, slightly elastic
-great tensile strength( can resist pulling)
-found most abundant in ligaments and tendons

elastic fibers

protein called elastin
- weaker than collagenous fibers
-highly stretchable
-common in body parts that stretchsuchs as the vocal cords, air tubes, skin, and blood vessels

reticular fibers

very thin collagen fibers
form delicate supporting networks
-supports soft organs, fat cells nerve and muscle cells

dense irregular connective tissue

-pimarily irregularly arranged collagen fibers; some elastic fibers; major cell type is the fibroblast.
-able to withstand tension exerted in many directions, provides structural strength
-located in the dermis of the skin

dense regular CT

-primarily parallel collagen fibers, a few elestic fibers, major cell type is fibroblast
-function- attatched muscles to bones or to muscle; attached bones to bones, withstands great tensile stress when pulling force is applied in one direction
-location, tendons, most ligaments, apopneruroses

adipose tissue

-matrix as in areolar, but very sparse,closely packed adiposecytes or fat cells have nucleus pushed to the side by large fat droplet
-function, provides reserve food fuel, insulates against heat loss supports and protects organs.
-location-under skin in the hypodermis, around kidneys and eyeballs; within abdomen in breast

areolar tissue

-gel-like matrix with all three fiber types; cells, fibroblast, macrophages, mast cells and some white blood cells.
-function- wraps and cushions organs; its macrophages phagocytize bacteria; plays important role in inflamation; holds and conveys tissue
-location-widely distributed under epithelia of body e.g forms lamina propria of mucous membranes; packaging organs; surrounds cappilaries


-tough, flexible but rigid
-can withstand tension and compression
-provides support, framework, attachments and protection
-matrix abundant with collagen and elastic fibers,
- predominant cells chondroblast and chondrocytes (encased within lacunae)
-not innerverted

hyaline cartilage

-amorphous but firm matrix, chondroblast produce the matrix
-supports and reinforces; has resilient cushioning properties; resist compressive stress
- forms most of the embryonic skeleton; covers the end of long bones in joint cavities; forms costal cartilage of the ribs, cartilage of the nose trachea, and larynx

elastic cartilage

-similar to hyaline cartilage but more elastic fibers in matrix
-maintains the shape of a structure while alowing great flexibility
-supports external ear


-matrix is similar to but less firm than that in hyaline cartilage, thick collagen fibers predominate
-tensile strength with the ability to absorb compressive shock
-intervertebral disc; pubic symphysis; disc of knee joint


most rigid CT
-matrix solid and hard due to mineral salts such as calcium phosphate and calcium carbonate
-function-protection and support, attachments for muscles, make blood cells, stores and releases inorganic salts, predominant cells called osteoblast, osteoclast and osteocytes ecased with lacunae


-liquid CT
-matrix called plasma
-plasma contains - white blood cells- fight diseases via phagocytosis -red blood cells- transport respiratory gases
-platelets- needed for blood clotting
-fibers of blood called plasma proteins
-Function- transport nutrients, hormones waste, respiratory gases and other substances

nervous tissue

found in brain, spinal cord and peripheral nerves
-cells called nerons and neuroglia


-transmit electrical impulses throughout body


-support cells
-highly mitotic

nervous system

regulate and control body functions

muscle tissue

-tissue specialized to contract or shorten
-muscle cellsare elongated referred to as muscle fibers
-well vascularized
-function-provide motion, maintain posture, generate heat

skeletal tissue

-long, cylindrical, multinucleate cells, obvious striations
-voluntary movement locomotion; locomotion manipulation of the environment; facial expression; voluntary control.
-in skeletal muscles, attached to bones or occasionally to skin.

cardiac muscle

-branching, striated, genaerally uninucleate cells that interdigitate at specialized junctions.
-as it contracts, it propels blood into the circulation; involuntary control
-the walls of the heart

smooth muscle

-spindle-shaped cells with central nucliei; no striations, cells arranged closely to form sheets
-propels substances or objects (foodstuffs, urine, a baby) along internal passageways; involuntary control.
-mostly in walls of hollow organs.

tissue repair

occurs in two major ways 1) regeneration 2) fibrosis
regeneration- the replacement of destroyed tissue with the same kind of tissue
fibrosis- involves the formation of scar tissue

four major membranes of the body

serous, mucous,synovial, cutaneous

serous membrane(wet)

-line body cavities that do not open to the body exterior
-form inner linings of the thorax and abdominal and covers the organs with the cavities
-composed of two layers- parital(line cavities) visceral(line surface of organs)
-cells secrete watery serous fluid, which lubricates surface

mucous membrane(wet)

-line cavities and tubes that open to the exterior of the body
-areas include- oral and nasal cavities, digestive tube, respiratory, urinary and reproductive ststems
-mucous membrane consist of epithilium which overlie a layer of loose connective tissue called the aminapropria (sub layer of mucous membrane, simple columnar, stratified squamous)
-membrane contain goblet cells

synovial membrane (wet)

-forms inner linings of joint cavities
-cells of membranes secrete a thick colorless synovial fluid into joint cavity

cutaneous membrane(dry)

skin-integumentary system
dry membrane


outer layer


middle layer


inside layer


superficial layer, outermost protective layer, composed of epithelial cells


-deep layer underneath the epidermis
-make up bulk of skin
-tough and leathery
-composed of epithelial cells
-well vascularized to supply epidermis
-well innervated
-regulate body temp

subcutaneous layer (hypodermis)

-not a skin layer
- found underneath the dermis layer of skin
-consist of adipose and areolar CT
-store fat
-anchors skin to underlying structures
-contain major blood vessels that supply the skin
-shock absorber

epidermis layer

-contain keratinized stratified squamous epithilium
-four cell types-kerotinocytes, melanocytes, langerhans cells, merkel cells


chief or most abundant cells in epidermis
-produce kertin (tough, water proofing protein)
-flaten cells with scale like apperance
-surface keratinocytes are dead, slough off


spider shaped cells
-produce melanin, (pigment)
-found in deepest layer of epidermis

langerhans cells

star shaped
-arise from bone marrow then migrate to epidermis
-known as macrophages (mature cells)

merkel cells

spiky appearance
-found at the junction between epidermis and dermis skin layers
-associated with a nerve disc forming a merkel disc

skin has four strata layers (thick have 5)

stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum.

stratum basale

deepest layer
-cells active in mitosis
-one layer
-containt young keritinocytes, melanocytes and merkel cells
-attached to dermis

stratum spinosum

-several layers of thickness
-keritinocytes have developed spiny projections (called prickle cells)
-langerhans cells most abundant

stratum granulosum

consist of 3-5 cell layers in thickness
-keritinocytes accumulate granuls in cytoplasm
-kertin forms

stratum lucidum (thick layer only)

abesnt in thin skin
-lies above granulosum layer
-few layers of dead keritinocytes

stratum corneum

superficial thick layer
-sloughing noted in this layer
-20-30 cell layers
-keritinocytes are shingle like in appearance

two dermis layers

papillary layer, reticular layer

papillary layer

thin superficial layer
-make up 20% of the dermis
-contain peg-like projections celled dermal papillae which produce the ridges of fingertips
-dermal papillae contain- capillary loops- produce nutrients to the epidermis - meissners corpuscles- touch receptors

reticular layer

deep layer
-makes up 80% of dermis
contains pacinan corpuscles- pressure sensitive receptors
- contain sweat and sebaceous glands


- major skin pigment color range,
-pigment from yellow-red-black
-local accumulation of melanin produce freckles and moles


yellowish-orange pigment
-abundant in soles and palms
-pigment acculates in the stratum corneum and hypodermis

oxygenated hemoglobin

red pigments of red blood cells
-produce pinkish tint to skin

alterations of skin color-redness

due to blushing, fever, inflamation, hyper tension and allergy

alterations of skin color-blanching

pale skin due to anemia of emotional stress

alterations of skin color-jaundice

yellowish appearance due to disorder of the adrenal glands

alterations of skin color-bruising

black blue due to hematoma(clotted blood mass)

sweat glands

-two major types-eccrine and apocrine
-located in all skin areas except nipples of breast and part of human genetalia
-two modified sweat glands-ceruminous glands, mammary glands

eccrine (merocrine) glands

most numerous
-abundant in palms, soles, forehead, and scalp
-duct extends to surface of skin, opens into a pore
-secretion- called sweat (prevents the body from over heating known as thermoregulation)
-composition-99%water, salts, nitrogen, waste, vitamin C, lactic acid, antibodies, pH 4-6
-regulatede by sympathetic division of ans
-emotional sweating called cold sweat

apocrine glands

-found most abundant in armpits and genital region
-larger in size than eccrine glands
-ducts empty into hair follicle
-secretion contains lipids and protiens
-odoless unless mixed with bacteria
-become fully funtion at puberty
-secretions do not function in thermoregulation

ceruminous glands

found in external ear canal, secrete earwax or cerumen, functions as protection

mammary glands

found in the breast; specialized to secrete milk

sebaceous glands

-secrete sebum (oily secretion)
-sebum softens and lubricates the hair and skin
-holocrine glands by function (cells accumulate sebum, swell and burst)
-sebum released into hair folicles and onto skin surface
-glands scattered throughout skin except in the palms and soles
-androgens (male-like hormones) stimulate the secretion of sebum
-glands become very active during puberty inactive at childhood
-blocked sebaceous gland ducts produce whiteheads and blackheads on skin
-inflamed sebaceous glands cause acne or pimples
-overeactive sebaceous glands cause seborrhea (oily scales on scalp) known as "cradle cap" in infants

hair follicles

-hair present in all skin areas except palms, soles, lips, nipples, and part of the external genitalia
-needed for protection and filtration
-hair produced in hair follicle
- follicle extends from epidermis into the dermis layer of skin

structure of hair follicle

-structure- hair bulb, root hair plexus, hair papilla, connective tiisue root sheath, epithelial root sheath, arrector pili

hair bulb

expanded base of hair follicle

root hair plexus

wrapped around bulb

hair papilla

nipple like; provides nutrients for hair growth

connective tissue root sheath

derived from the dermis; makeup outer wall of the hair follicle

epithelial root sheath

derived from an invagination of the epidermis

arrrector pili

associated with each hair follicle, is a bundle of smooth muscle cells

structure of hair



major region of hair; extends above skin


embeded in dermis

shapes of shafts

-flat and ribbon

layers of shaft



central core; absent in fine hair


middle bulky layers around medula


outermost layer, composed of overlapping cells

hair types

vellus- fine
terminal hair-coarse, found on scalp, eyebrows, pubic region, axillary, face and chest

hair growth

avg, 2mm/week
alopecia-thining or baldness condition of scalp, male pattern baldness most common


-protective coverings of fingers and toes
-contains protein keratin
-nail structure -free edge, body root
-nail matrix- proximal portion producing nail growth
-lamule- whitish area on nail at proximal end

skin cancer

a tumor that does not spread is benign
-a tumor that spreads (metastisize) is malignant or cancerous
-most common type of skin cancer is exposure to ultraviolet light
-three types of cancer-basal, squamous, melanoma

basal cell carcinoma

least malignant and most common skin cancer
-lesions occur on the face
-80% of skin cancer
-highly curable
-proliferate, invading the dermis and epidermis

squamous cell carcinoma

-second most common skinn cancer
-arise from the keratinocytes of the stratum spinosum
-lesion arise on head, ears, scalp, lower lip and hands
curable if it does not spread


cancer of the melanocytes and most dangerous
- highly metastatic and resistant to chemotherapy
-originates from preexisting moles that get larger


causes tissue damage resluting from excessive heat or exposure to chemicals

first degree burn

-superficial partial thickness burn
-pain, redness, flaring of skin
-ex mild sunburn
-healing 7-10 days

second degree burn

-deep partial thickness burn
-damages the epidermis and upper layer of dermis
-some skin appendages are lost
-this wound occurs from open flames, hot objects and chemicals
-ex. formation of a blister
-healing 2-3 weeks

third degree burn

-full thickness burn
-damages the epidermis and dermis layer and accessory organs in the skin
- all skin functions are lost
-life threatening conditions
-skin becomes tough leathery and numb, skin graphing required, leaving extensive scars

rule of nines

a method to estimate the extent and severity of burns
-it divides the body into 11 areas, each accounting for 9% of the total body area plus 1% for the genitals

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