also called cutaneous membrane

epidermis: outermost layer

dermis: papillary/reticular layer; mostly dense connective tissue

hypodermis: fat, protective layer

mucous membranes

composed of epithelium resting on loose connective tissue membrane

line body cavities that are open to the outside

form barrier to protect against pathogens

body temperature regulation

aids in excretion of urea and uric acid

synthesizes vitamin D

protects against: mechanical damage, chemical damage, bacterial damage, ultraviolet radiation, thermal damage, and desiccation (drying out)

stratum corneum: 20-30 cell layers thick, dead cells shed all the time

stratum basale: bottom-most layer, next to dermis

stem cells, melanocytes (make melanin)

oil glands found all over the skin except on the palms of the hands and soles of feet

ducts usually empty into a hair follicle but some open directly onto skin surface

produces sebum

product of sebaceous glands

mixture of oily substances and fragmented cells

lubricant that keeps the hair soft and moist and prevents hair from becoming brittle

contains chemicals that kill bacteria

two kinds:

eccrine - more numerous, secrete sweat (water, salts, vitamin C, metabolic wastes) which is acidic (helps inhibit growth of bacteria on skin's surface), involved in regulation of body temperature

apocrine - found in axillary and genital areas of the body; larger than eccrine glands and their ducts empty into hair follicles; secretion contains fatty acids and proteins which bacteria use as nutrients and causes it to take on unpleasant odor

fibrous proteins that make the epidermis a tough protective layer

outside layer of epidermis

20-30 cells deep, shed dead cells all the time

bottom-most layer of epidermis

next to dermis

melanocytes make melanin

stem cells

located in stratum basale (bottom-most layer of epidermis)

make melanin

any micro organism that can make us sick (bacteria, virus, fungi)

cells that engulf foreign invaders (pathogens)

ex. macrophage, neutrophil

natural killer (NK) cells

spontaneously lyse (break open) any invading cells

NK cells are not phagocytic

1. network of lymphatic vessels - return fluid to circulation

2. lymphoid tissues and organs - fluid monitored by immune cells as it passes through lymph nodes

=clear water

fluid component of blood that is leaked out of blood vessels (capillaries close to brain/retina are not leaky)

fluid picked up by lymphatic vessels and returned to heart

help protect body by removing foreign material such as bacteria and tumor cells from the lymphatic stream and by producing lymphocytes that function in the immune response

macrophages and lymphocytes (type of whtite blood cell) are located in the lymph nodes

spleen, thymus gland, tonsils, and Peyer's patches of the intestine

only the lymph nodes filter lymph

nonspecific response to tissue injury

1. injury, 2. release of proinflammatory chemicals,

3. blood vessels dilate, 4. redness, heat

indicators: redness, heat, swelling, pain (due to increased blood to injury site)

end result: bring chemicals and cells to site of injury for protection and cleanup; tissue repair

neutrophils squeeze through capillary walls at injury site (during inflmmatory response) to perform cleanup

refers to group of at least 20 plasma proteins (enzymes, regulators) that circulate in the blood in an inactive state

becomes activated when becomes attached/fixed to foreign cells such as bacteria, fungi, or mismatched red blood cells

activation of first enzyme starts cascade and leads to inflammation and membrane attack complex (MAC)

swelling

enhances innate defenses by attacking microorganisms directly or hindering their ability to reproduce

most important: complement proteins and interferon

antibiotic

drug that will kill bacteria

bacteria become unaffected by antibiotic drugs; evolution/natural selection

individuals within a population may vary and some variability is heritable

survival is not random; those best suited to environment survive

mutation = change in DNA, if mutation occurs in gametes you can pass it down to offspring

respond immediately to protect body from foreign substances no matter what they are

skin, mucous membranes, phagocytes, natural killer cells, inflammatory response, antimicrobial proteins, fever

disease  that can be passed between mammal species (ex. rabies)