Anatomy and Physiology Chapter 4

tissue

collections of specialized cells and cell products that perform a limited number of functions

histology

the study of tissues

epithelial tissue

covers exposed surfaces, lines interval passageways and chambers, produces glanular secretions, includes epithelia and glands, layers of cells that cover internal and/or external structures

connective tissue

fills internal spaces, provides structural support, stores energy

muscle tissue

contracts to produce active movement

neural tissue

conducts electrical impulses, carries information

glands

composed of secreting cells derived from epithelia

5 characteristics of epithelia

cells bound closely together, one exposed surface, attached to underlying tissue by a basement membrane, absence of blood vessels so thy gain nutrients from underling tissue or exposed surface, continually replaced

4 functions f epithelia

physical protection, control permeability, provide sensation, produce specialized secretions

glandular epithelium

most or all cells produce secretions

exocrine

secretions are discharged onto the surface of the epithelium: enzymes entering digestive tract, perspiration on the skin, and milk produced by mammary glands

endocrine

secretions are released into the surrounding tissue and blood, called hormones and act as chemical messengers and regulate or coordinate the activities of other tissues or organs

apical surface

exposed to an internal or external environment

intercellular connections

connections between epithelial cells and other epithelial cells or the basement membrane

how epithelia renew ad repair themselves

through continuous division of unspecialized cells known as stem cells (germanative cells)

stem (germanative) cells

unspecialized cells found in the deepest layers of the epithelium, near the basement membrane

simple epithelium

single layer of cells covering a basement membrane, thin and fragile and dont provide much mechanical protection, only found in protected areas of the body, like heart chambers and blood vessels and the lungs

stratified epithelium

more protection than simple epithelium due to several layers of cells above basement membrane, in areas subject to more stress, like the surface of the skin, lining of mouth and anus

squamous epithelium

cells are thin and flat, nucleus occupies the widest part of cell, looks like a fried egg from the side

cuboidal epithelium

resemble large, hexagonal boxes, appear square in section view

columnar epithelium

cells are hexagonal but taller and slender, very tall, nuclei in middle, look like rectangles in section view

3 components of all connective tissues

specialized cells, extracellular protein fibers, ground substance

ground substance

fills the space between the cells and surrounds connective tissue fibers, clear, colorless, maple syrup consistency, dense consistency, slows bacteria and other pathogens, allowing easier capture by phagocytes

matrix

formed by extracellular fibers and ground substance surrounding cells, accounts for most of the volume of connective tissue

no

are connective tissues ever exposed to the outside world?

4 functions of connective tissue

support and protection, transportation of materials, storage of energy reserves, defense of the body

3 major connective tissue types

connective tissue proper, fluid connective tissue, supporting connective tissue

connective tissue proper

consists of many cell types within a matrix containing extracellular fibers and a syrupy ground state; tissue underlying skin, fatty tissue. tendons and ligaments

fluid connective tissue

have a distinctive population of cells suspended in a matrix of watery ground substance containing dissolved proteins; blood and lymph

supporting connective tissues

less diverse cell population than connective tissue proper, and a matrix of dense ground substance and closely packed fibers; bone and cartilage

fibroblasts

most abundant, permanent residents, produce connective tissue fibers and ground substance (fibrocytes are next in abundance and they maintain connective tissue fibers)

macrophages

scattered through the matrix, "big eater" cells engulf damaged cells or pathogens in tissue, release chemicals that mobilize the immune system and attract more macrophages

fat cells (adipose cells)

permanent residents, contain a large droplet of liquid with organelles squeezed o one side, number of these vary among connective tissues, regions, and individuals

mast cells

small, mobile, near blood vessels, cytoplasm has vesicles with chemicals that begin body's defense activities after injury or infection once they are released

antibodies

proteins that destroy invading microorganisms or foreign substances

collagen fibers

long, straight, unbranched, strong but flexible fibers that are the most common fibers in connective tissue proper

elastic fibers

contain protein called elastin, these fibers are branched and wavy, return to original length after stretching

reticular fibers

made up of same protein subunits as collagen fibers, but arranged differently, least common of 3 connective tissue fibers, thinner than collagen fibers, form a branching, interwoven framework in various organs, made from protein subunits secreted by fibroblasts

2 types of connective tissue proper

dense and loose connective tissue

3 types of loose connective tissue

areolar tissue, adipose tissue, reticular tissue

areolar tissue

least specialized, contains all the cells and fibers in any connective tissue, extensive blood supply, forms layer that separated skin from deeper tissue, stretchiness allows for independent movement of skin and muscle, blood supply provides metabolic needs of epithelial tissue

adipose tissue

fat, loosely connected tissue dominated by fat cells, provides padding and shock absorption, insulates, and stores energy

reticular tissue

loose connective tissue that forms a complex 3D network, stabilize positions of functional cells I lymph nodes and bone marrow, spleen and liver

tendon

cords of dense regular connective tissue that attach skeletal muscle to bones

ligament

resemble tendons, but connect bone to bone

plasma

watery matrix in blood

3 types of cells found in blood

red blood cells, white blood cells, platelets

red blood cells

almost 1/2 volume of blood, transport oxygen

white blood cells

important components of the immune system

platelets

cell fragments that function in blood clotting

3 fluids that constitute most of the extracellular fluid in the body

blood, lymph, and interstitial

2 types of dense connective tissue

tendons and ligaments

cartilage

connective tissue with a gelatinous matrix containing an abundance of fibers

chondrocytes

only living cells in the matrix of cartilage

problem that cartilage is avascular

chondrocytes must get nutrients and eliminate waste by diffusion through the matrix, also limits repair abilities of cartilage

hard calcium compounds and flexible collagen fibers

the matrix of bone consists mainly of...

no

is bone avascular

mucous membrane

line cavities that communicate with the exterior, digestive, respiratory, reproductive, and urinary tracts, keeps epithelial cells moist at all times

serous membrane

membrane of simple epithelium supported by areolar tissue, line ventral cavities of the body, pleura-lungs, peritoneum-abdominal cavity (abdominal organs- liver, stomach...), pericardium-heart

cutaneous membrane

skin, covers body's surface, stratified squamous epithelium and a layer of areolar tissue and underlying connective tissue, thick, waterproof, usually dry

synovial membrane

mainly areolar tissue and an incomplete epithelial tissue, lines joint cavities and produce fluid within the joint

4 main membranes in the body

mucous, serous, cutaneous, synovial

3 types of muscle

skeletal muscle tissue, cardiac muscle tissue, smooth muscle tissue

neurons

a cell in the neural tissue specialized for intercellular communications by changes in the membrane potential and synaptic connections

neuroglina

cells of the CNS that support ad protect the neurons

3 main components of a neuron

cell body, axon, dendrites

inflammation

isolates area from healthy, neighboring tissue while damaged cells, tissue components, and any dangerous microorganisms are cleaned up, a nonspecific defense mechanism that operates at the tissue level, characterized by redness, swelling, warmth, and pain

regeneration

damaged tissues are replaced or repaired to restore normal function, fibroblasts produce a dense network of collagen fibers called scar tissue

what happens to tissue structure when you age

change with age, repair speed and effectiveness decreases, epithelia are thinner, connective tissue more fragile, bruise easier, bones more brittle

increase; 25

cancer rates _____ with age, and _____% of all Americans develop cancer in their lives

Cutaneous membrane and accessory structures

2 components of the integumentary system

Cutaneous membrane

Skin, organ composed of the superficial epithelium (epidermis) and underlying tissue of the dermis

Dermis

Connective tissue later deep beneath the epidermis of skin

Epidermis

Epithelium covering the surface of the skin

Epidermis and dermis

2 layers of the cutaneous membrane

Accessory structures

Hair, nails, variety of exocrine glands, hair, sweat glands, small muscles, touch receptors, nerves, and other glands

Loose connective tissue that separates the integumentary from deeper tissue

Hypodermis; subcutaneous layer

Hypodermis

Separates integumentary from deeper tissues and organs

5 functions of skin

Protection, temperature maintenance, syntheses and storage of nutrient, sensory reception, excretion and secretion

Stratum basal

Deepest epidermal layer, cells of this layer are firmly attached to the basement membrane by hemidesmosomes

No

Do blood vessels reach the epidermis?

Basal cells or germinative cells

Large stem cells that dominate the stratum basal

Melanocyte

Synthesize melanin

Melanin

Brown/yellow brown/black pigment that colors the epidermis, it is a protein

Intermediate strata

3 layers, cells progressively displaced and specialized as they become the outer protection of the skin, stratum spinosum deepest, then stratum lucidum, then stratum granulosum

Keratin

Extremely durable, water resistant protein in hair, skin, nails, and calluses

Stratum corneum

At exposed later of skin, 15-30 layers of dead, flattened epithelial cells that have accumulated large amounts of keratin

Keratinized (cornified)

Cells that have accumulated a large amount of keratin

7 to 10 days; 2 weeks

How long does it take for cells to move from the stratum basal to the stratum corneum? How long do they stay there?

Hey is UV radiation from the sun beneficial?

Stimulated the synthesis of vitamin d3 in the epidermis

Albinism

Disease where melanin isn't produced by melanocytes despite normal abundance and distribution

Vitamin D3

Epidermal cells in the stratum spinosum convert a cholesterol based steroid into this when exposed to UV radiation, its absorbed from the liver and converted by the kidneys into calcitrol which aids in calcium absorption by the small intestine

3 types of skin cancer

Basal cell carcinoma, squamous cell carcinoma, malignant melanomas

Basal cell carcinoma

Which type of skin cancer is the most common?

Malignant melanomas

Which type of skin cancer is the most dangerous?

Dead, keratinized cells

Hair is composed of ______ that has been pushed to the skin surface

Arector pili

Bundle of smooth muscle cells, pull on the hair follicle, forcing hair to stand up, caused by emotional state or feeling cold

Sebaceous and sweat glands

2 types of exocrine glands

Sebaceous gland

Oil glands, discharge oily lipid secretion into hair follicles or on skin

Sweat gland

Perspiration maintain body temp; apocrine sweat on nipple, armpit, pubic hair; merocrine sweat directly on skin