midterm 1 study

what is homeostasis?

ability to maintain stable internal environment despite changing conditions

what are the 5 steps of homeostasis control mechanism?

stimulus → receptor → control center → effector → response

what does negative feedback do?

reverses a change and returns a variable toward its normal range

what does positive feedback do?

amplifies a change until a climactic event stops the loop

high blood glucose stimulates release of what?

insulin

low blood glucose stimulates release of what?

glucagon

what are the 4 tissue types?

epithelial, muscle, nervous, connective

main function and feature of epithelial tissue?

covers/lines surfaces

tightly packed cells with little extracellular matrix

main feature of connective tissue?

cells within extracellular matrix

supports, binds, protects, transports

skeletal muscle

voluntary? striated? function? location?

voluntary

striated

moves body and helps produce heat

attached to bones

cardiac muscle

voluntary? striated? function? location?

not voluntary

striated

pumps blood

in heart

smooth muscle

voluntary? striated? function? location?

not voluntary

not striated

moved substances through organs and controls diameter

walls of hollow organs + blood vessels

primary function of neurons

receive, process, transmit nerve impulses + electrical signals

primary function of glial cells

support, protect, nourish, insulates neurons

gray matter vs. white matter

gray = cell bodies/processing

white = myelinated axons/signal transmission

3 protective barriers of the integument

chemical, physical, biological

major functions of integument

protection, form, hydration, temperature, vitamin D, sensation, blood reservoir, excretion

how does skin release heat?

vasodilation increases blood flow

how does skin conserve heat?

vasoconstriction decreases blood

what is the vitamin D pathway?

UVB → skin → liver → kidney → calcitriol → small intestine

what does calcitriol do?

tells small intestine to increase calcium and phosphate absorption

epidermal layers superficial to deep

corneum → lucidum (thick skin only) → granulosum → spinosum → basale

where is stratum lucidum found?

thick skin, palms and soles

what is special about the stratum basale?

deepest epidermal layer, has mitotically active cells

why do cells of the stratum spinosum look spiny?

cell shrinks, desmosomes stay attached, looks spiny

what do melanocytes produce?

melanin → skin color + protects DNA from UV

papillary vs. reticular dermis?

papillary = superficial, areolar connective tissue

reticular = deep, dense irregular connective tissue

apocrine/merocrine sweat glands: main function and destination?

temperature control

sweat travels to skin surface

where are merocrine glands especially abundant?

palms, soles, forehead

apocrine sweat glands: location and where does secretion go?

mainly axillary/anogenital regions

secretion enters hair follicle

what do sebaceous glands produce and why?

sebum

lubricates/protects skin and hair

helps prevent water loss

merocrine vs. holocrine secretion

merocrine → exocytosis, cell survives

holocrine → cell dies, releases contents

what does arrector pili muscle do?

contracts to pull hair upright

goosebumps

what produces shivering?

rapid involuntary contractions of skeletal muscle

generates heat

most immediate critical threat from severe burns?

dehydration (fluid loss) → decreased blood volume → risk of hypovolemic chock

what happens to the skin barrier in atopic dermatitis?

barrier weakens → irritants/allergens go through → inflammation

endocrine vs. exocrine glands

endocrine → hormone into blood

exocrine → products through ducts to a surface

autocrine vs. paracrine signaling

autocrine → affects same cell

paracrine → affects nearby cells

3 types of hormone release stimuli

hormonal, humoral, neural

what is hormonal stimulus?

hormone to hormone

what is humoral stimulus?

change in blood triggers release

what is neural stimulus?

nervous-system triggers release

steroid hormones are synthesized from what?

cholesterol

hydrophilic hormones interact with target cells how?

bind membrane receptors → second messengers → alters existing protein/enzyme activity

hydrophobic hormones interact with target cells how?

cross membrane → intracellular receptor → alter gene expression/protein synthesis

why are t3/t4 unusual amino-acid-derived hormones?

they are amino-acid derived but hydrophobic and use intracellular receptors

what is signal amplification?

one hormone signal activates many downstream molecules, producing a large response

what is hormone synergism?

two or more hormones together produce a greater effect

what is hormone permissiveness?

one hormone allows another hormone to produce its full effect

what is hormone antagonism?

two hormones have opposite effects on the same variable

ex: calcitonin + PTH

adenohypophysis vs. neurohypophysis

adenohypophysis → anterior pituitary

neurohypophysis → posterior pituitary

anterior pituitary cascade?

hypothalamus → regulatory hormone → anterior pituitary → target gland/hormone

what hormones does the posterior pituitary release and where are they made?

ADH and oxytocin

both made in the hypothalamus

what does ADH do?

tells kidneys to reabsorb more water → less urine

what does oxytocin do?

stimulates uterine contractions and milk ejection

TSH → source + function?

anterior pituitary → stimulates thyroid to release t3/t4

FSH → source + function?

anterior pituitary → promotes egg development and sperm production

LH → source + function?

anterior pituitary → ovulation and stimulates testosterone production

ACTH → source + function?

anterior pituitary → stimulates adrenal cortex to release cortisol

GH → source + function?

anterior pituitary → promotes growth, especially bone and muscle

melatonin → source + function?

pineal gland → regulates sleep and circadian rhythms

t3/t4 → source + function?

thyroid gland → increase metabolic rate and supports growth/development

calcitonin → source + function?

thyroid gland → lowers blood calcium

PTH → source + function?

parathyroid gland → raises blood calcium

calcitonin and PTH have what relationship?

antagonistic

calcitonin lowers calcium, PTH raises calcium

adrenal cortex vs. adrenal medulla

cortex → steroid hormones

medulla → EPI/NE

aldosterone → source + function?

adrenal cortex → retains Na+ and water supports blood volume/pressure

cortisol → source + function?

adrenal cortex → long-term stress, increases available energy/blood glucose

epinephrine → source + function?

adrenal medulla → fight/flight, increases heart rate and energy availability

norepinephrine → source + function?

adrenal medulla → vasoconstriction and increased blood pressure

what stimulus causes adrenal medulla hormone release?

neural stimulation from the sympathetic nervous system

what chemical class is produced by the adrenal cortex zonas?

steroid hormones

insulin → source + function?

pancreas → lowers blood glucose, promotes uptake/storage

glucagon → source + function?

pancreas → raises blood glucose, promotes glucose release into blood

estrogen → source + function?

ovaries → female reproductive development + menstrual cycle regulation

progesterone → source + function?

ovaries → prepares/maintains the uterus for pregnancy

testosterone → source + function?

testes → male reproductive development + supports sperm production

inhibin → source + function?

ovaries/testes → inhibits FSH

what do thymic hormones do?

help T lymphocytes develop and mature

TRH → TSH → T3/T4: what happens if t3/t4 rise normally?

negative feedback decreases TRH and TSH secretion

hypersecreting hypothalamic tumor ignores feedback: effect on TSH and TH?

excess hypothalamic stimulation → increased TSH → increased thyroid hormone