A&P exam 2 objectives

name the four primary classes into which all adult tissues are classified

epithelial, connective, nervous , and muscular tissues

name the three embryonic germ layers and some adult tissues derived from each

ectoderm, endoderm, mesoder

Ectoderm

outer layer, gives rise to epidermis and nervous system

Endoderm

Inner layer, gives rise to mucous membrane lining digestive and respiratory tracts, digestive glands

Mesoderm

middle layer, becomes gelatinous tissue called mesenchyme

* wispy collagen fibers and fibroblasts in gel matrix
* gives rise to cartilage, bone, blood, muscle

visualize the three-dimensional shape of a structure from a two-dimensional tissue section

longitudinal section , cross section (transverse section), oblique section

longitudinal section

tissue cut on its long axis

cross section (transverse section)

tissue cut perpendicular to long axis of organ

oblique section

tissue cut at angle between cross and longitudinal sections

structure of epithelia

* sheets of closely adhering cells, one or more cells think


* coves body surfaces and lines body cavities
* upper surface usually exposed to the environment or an internal space in the body
* constitutes most glands
* avascular (does not have blood vessels)

functions of epithelia

* protect deeper tissues from injury and infection
* produce and release chemical secretions
* excrete waste
* absorb chemicals including nutrients
* selectively filter substances
* sense stimuli

describe the junctions that hold cells and tissues together

* cell junctions
* tight junctions
* desmosomes
* gap communicating

cell junction

* connections between two cells
* communication, resist mechanical stress, control what moves through the gaps between them

tight junctions

* linkage between two adjacent cells by transmembrane cell-adhesion proteins


* seals off intercellular space, making it difficult for substance to pass between cells

desmosomes

* patch that holds cells together (like a clothing snap)
* keeps cells from pulling apart, resist mechanical stress
* (hemidesmosomes) half anchors basal cells of an epithelium to underlying basement membrane

gap communicating junction

* formed by ring-like connexons
* 6 transmembrane proteins
* ions, nutrients and other small solutions pass between cells
* located in the cardiac and smooth muscle, embryonic tissue, lens and cornea

glands

cell or organs that secretes substance for use elsewhere in the body or releases them from elimination from the body

* epithelial tissue
* connective tissue

secretion

products useful to the body

* saliva

Excretion

waste product

* urination

endocrine gland

have no ducts; secrete hormones directly into blood

* thyroid, adrenal, and pituitary glands

exocrine glands

maintain their contact with surface of epithelium by way of a duct

* (external) sweat, tear glands
* (internal) pancreas, salivary glands

unicellular glands

found in an epithelium that is predominantly nonsecretory

* can be exocrine or endocrine
* goblet cells
* secrete mucus

capsule

connective tissue covering of exocrine gland

* sac around the heart

Stroma

connective tissue framework of the gland

* supports and organizes glandular tissue

parenchyma

cells that perform the tasks of synthesis and secretion

* framework, structure

Tubular (classification of glands)

narrow secretory portion

\-eccrine sweat gland

acinar (classification of glands)

secretory cells form dilated sac (acinus or alveolus)

* mammary gland

tubuloacinar (classification of glands)

both tubular and acinar portions

serous glands

* produce thin, watery secretions
* milk, tears, digestive juices

mucous glands

* produce glycoproteins, mucin, which absorbs water to form musuc
* goblet cells: unicellular musous glands

Mixed glands

* contain both serous and mucous cell types and produce a mixture of the two types of secretions
* tears can change and saliva glands

apocrine secretion

lipid droplet covered by membrane and cytoplasm buds from cell surface (budding)

* milk fat secretion

merocrine secretion

(used by eccrine glands)

* uses vesicles that release their secretion by exocytosis
* tear glands, pancreas, gastric glands
* lowest lipid concentration

holocrine secretion

cells accumulate a product until they disintegrate

* secret a mixture of cell fragments and synthesized substances
* oil glands of scalp adn skin, gland of eyelids

cutaneous membrane (the skin)

largest membrane in the body

* stratified squamous epithelium (epidermis) resting on layer of connective tissue (dermis)
* relatively dry layer serves protective function
* compound membrane

mucous membrane (mucosa)

lines passages that open to the external environment (digestive tract)

* absorptive, secretory, and protective functions
* often has mucus producing goblet cells
* compound

serous membrane (serosa)

internal membrane

* double membrane
* produces serous fluid that arises from blood
* covers organs and lines walls of body cavities

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tissue growth

increasing the number of cells or size of existing cells

hyperplasia

growth through cell multiplication

hypertrophy

enlargement of preexisting cells

* muscle growth through exercise
* accumulation of body fat

neoplasia

development of a tumor

* composed of abnormal, nonfunctional tissue

differentiation

development of more specialized form and function by unspecialized tissue

* embryonic mesenchyme becoming cartilage and bone

metaplasia

changing from one type of mature tissue to another

* simple cuboidal tissue of vagina before puberty changes to stratified squamous after puberty

developmental plasticity

ability of a stem cell to give rise to a diversity of mature cells types

totipotent

having the potential to develop into any type of fully differentiated human cell including accessory organs of pregnancy

* most plasistity
* cells of the very early embryo
* twins separate in cells

pluripotent

can develop into a type of cell in the embryo (but not accessory organs of pregnancy)

* cells of inner cell mass of embryo (blastocyts)

multipotent

able to develop into two or more cell lines

* bone marrow stem cells

unipotent

produce only one cell type

* cells giving rise to sperm

induced pluripotent stem cells (iPS Cells)

starts as a multipotent stem cell, reprogrammed to mimic a pluripotent stem cell

stem cells

* adult
* undifferentiated cells that give rise to keratinocytes
* in deeper layers of the epidermis (stratum basale)
* high metabolism= close to the source of nutrition

embryonic stem cells

* pluripotent stem cells
* can divide more or become any type of cell in the body
* can be used to regenerate or repair diseased tissue and organs

regeneration

replacement of dead or damaged cells by the same type of cells as before

* restores normal function
* ex: minor skin or liver injuries

fibrosis

replacement of damaged cells with scar tissue

* scar holds organs together, but does not restore function
* repair of severe cuts and burns, scarring of lungs in tuberculosis

simple squamous epithelium

* single row of thin cells
* permits rapid diffusion or transport of substances
* secretes serous fluid
* location: alveoli, glomeruli, endothelium, and serosa

simple cuboidal epithelium

* single layer of square or round cells
* absorption and secretion, mucus production and movement
* location: liver, thyroid, mammary and salivary glands, bronchioles, and kidney tubules

simple columnar epithelium

* single row of tall, narrow cells
* oval nuclei in basal half of cell
* brush border of microvilli, ciliated in some organs, may possess goblet cells
* absorption and secretion; secretion of mucus

location: lining of GI tract, uterus, kidney, and uterine tubes

pseudostratified epithelium

* looks multilayered, but all cells touch basement membrane
* nuclei at several layers
* has cilia and goblet cells
* secretes and propels mucus

location: respiratory tract and portions of male urethra

keratinized stratified squamous epithelium

* multiple cell layers; cells become flat and scaly toward surface
* resists abrasion; retards water loss through skin; resists penetration by pathogenic organisms

location: epidermis; palms and soles heavily keratinized

non-keratinized stratified squamous epithelium

* same as keratinized epithelium without surface layer of dead cells
* resists abrasion and penetration of pathogens

locations: tongue, oral mucosa, esophagus, and vagina

stratified cuboidal epithelium

* two or more cell layers; surface cells square or round
* secretes sweat; produces sperm, produces ovarian hormones
* locations: sweat gland ducts; ovarian follicles and seminiferous tubules

transitional epithelium

* multilayered epithelium with surface cells that change from round to flat when stretched
* allows for filling of urinary tract
* location: ureter and bladder

functions of connective tissue

* connecting organs
* support
* physical protection
* immune protection
* movement
* storage
* heat production
* transport

connecting organs

tendons and ligaments

support

bones and cartilage

physical protection

cranium, ribs, sternum

immune protection

white blood cells attack foreign invaders

movement

bones provide lever system

storage

fat, calcium, phosphorus

heat production

metabolism of browns fat in infants

transport

blood

cells of fibrous connective tissue

* fibroblasts
* macrophages
* leukocytes
* plasma cells
* mast cells
* adipocyte

fibroblast

produce fibers and ground substance of matrix

macrophages

phagocytize foreign material and activate immune system when they sense foreign matter (antigens)

leukocyte

white blood cells

* neutrophils attack bacteria
* lymphocytes react against bacteria, toxins and other foreign agents

plasma cells

synthesize antibodies

mast cells

often found alongside blood vessels

* secrete heparin to inhibit clotting
* secrete histamine to dilate blood vessels

adipocytes

store triglycerides (fat molecules)

collagenous fibers

* collagen is most abundant of the body’s proteins 25%
* tough, flexible, and stretch-resistant
* tendons, ligament, and deep layer of the skin are mostly collagen
* less visible in matrix of cartilage and bone

reticular fibers

* thin collagen fibers coated with glycoprotein
* form framework of spleen and lymph nodes

elastic fibers

* thinner than collagenous fibers
* branch and rejoin each other
* made of protein called elastin
* allows stretch and recoil

areolar tissue

* loosely organized fibers, abundant blood vessels
* underlies epithelia, in serous membranes, between muscles, passageways for nerves and blood vessels

reticular tissue

* mesh of reticular fibers and fibroblasts
* forms supportive stroma (framework) for lymphatic organs
* found in lymph nodes, spleen, thymus, and bone marrow

dense regular connective tissue

* densely packed, parallel collagen fibers
* compressed fibroblast nuclei
* elastic tissue forms wavy sheets in some locations
* tendons attach muscles to bones and ligaments home bones together

dense irregular connective tissue

* densely packed, randomly arranged, collagen fibers and few visible cells
* withstands unpredictable stresses

location: deeper layer of skin; capsules around organs

atrophy

shrinkage of tissue through loss in cell size or number

* senile atrophy through normal aging
* disuse atrophy from lack of use

necrosis

pathological tissue death due to trauma, toxins, or infections

infarction

sudden death to tissue when blood supply is cut off

gangrene

tissue necrosis due to insufficient blood supply (usually involved infection)

dry gangrene

common complication of diabetes

wet gangrene

liquefaction of internal organs with infection

gas gangrene

usually from infection of soil bacterium that results in hydrogen bubbles in tissues

apoptosis

programmed cell death

adipose tissue

Fat, tissue in which adipocytes are the dominant cell type

* primary energy storage, insulation, cushioning
* subcutaneous fat and organ packing
* brown fat of juveniles produces heat

white fat

main type of fat in adults

* provides thermal insulation
* cushions organs such as eyeballs, kidneys
* contributes to body contours- female breasts and hips

brown fat

in fetuses, infants, children

* color comes from blood vessels and mitochondrial enzymes
* heat-generating tissue

hyaline cartilage

* clear, glassy appearance because of fineness of collagen fibers
* eases joint movement, holds air way open, moves vocal cords, growth of juvenile long bone
* location: articular cartilage, costal cartilage, trachea, larynx, fetal skeleton

Elastic cartilage

* cartilage containing abundance of elastic fibers
* covered with perichondrium
* provides flexible, elastic support
* location: external ear and epiglottis

fibrocartilage

* cartilage containing large, coarse bundles of collagen fibers
* resist compression and absorbs shock
* location: pubic symphysis, menisci, and intervertebral discs

compact bone

* arranged in cylinders that surround central canals that run longitudinally through shafts of long bones
* blood vessels and nerves travel through central canal
* bone matric deposited in concentric lamellae

excitability

ability to respond to stimuli by changing membrane potential

* nervous and muscular tissue