Hormone life history

Question 1

what determines the effects of a hormone

Answer 1

depend largely on their concentration in blood and extracellular fluid
because of this disease results when hormone concentrations are either too high or too low

Question 2

what three factors determines the hormone concentration

Answer 2

1. rate of production
2. rate of delivery
3. rate of degradation and elimination

Question 3

what is the life history of a hormone

Answer 3

hormones - bile - gi - excretion

Question 4

what us a humoral stimulus

Answer 4

hormone release casued by altered levels of certain critical ions or nutrients
Ex. thyroid hormone
the low concentration of Ca2 in capillary blood
response - parathyroid glands secrete parathyroid hormone (PTH) which increases blood Ca2

Question 5

what is a neural stimulus

Answer 5

hormone release caused by neural input
stimulus - action potentials in preganglionic sympathetic fibers to adrenal medulla
response - adrenal medulla cells secrete epinephrine and norepinephrine

Question 6

what is a hormonal stimulus

Answer 6

hormones released by another hormone (a tropic hormone)
stimulus - from hypothalamus
response - anterior pituitary gland secretes hormones that stimulate other endrocrine glands to secret hormones

Question 7

for a tissue to response to feedback via hormone stimulus, what does it need to have

Answer 7

receptors for that hormone

Question 8

what is the difference between androgenous and exdrogenous

Answer 8

androgenous - made in the body
exdrogenous - taken into the body

Question 9

how do hormones circulate the blood

Answer 9

either free or bound to large protiens
water soluable - no specific transport mechanism
lipid soluable - transport proteins

Question 10

what are the most common transport protein

Answer 10

1. albumin and transthyretin : bind small ligands, general transport morecules - most common
2. specific transport proteins
   (corticosteroids binding globulin - stress hormones
   thyroxine binding globulin - t3 and t4
   sex hormone binding globulin - sex hormone

Question 11

what effects the rate of delivery

Answer 11

protein binding impacts metabolism and bioactivty of circulating
- free hormone activity, bound inactive hormone, plasma carrier
- synthesis and degration

Question 12

what is a free hormone

Answer 12

bioactive form that signals to turn a hormone on and off

Question 13

how are hormones degraded or metabolized

Answer 13

some are metabolized at their target cells (leave the blood and go to target organ)
some are metabolized in circulation
from enzymes in the liver or kidneys
more are excreted via the kidneys

Question 14

what is the rate of degration

Answer 14

the half life - the time during which the concentration of hormones decreases to 50% of its initial volume
shutting off secretion of a hormone that has a very short half life causes circulating hormone concentration to plummet

Question 15

what would happen if a hormone had a half-life that was long

Answer 15

it would take a while for it to dissapear from the bloodstream

Question 16

what is MCR

Answer 16

metabolic clearance rate - romoval of hormones from circulation, the volume of plasma cleared of the hormone per unit time
the mrc and and half life are inversly proportional, metabolic clearance life is the opposite to half life
if there is a fast half life - metabolic rate is high

Question 17

what is metabolic degradation

Answer 17

excretion of hormone metabolites occur through the bile or urine
target cells may internalize the hormone and degrade it

Question 18

why is the kidney important

Answer 18

urine is a very good way to measure hormone levels and non invasive target organ because the urine provides a good diagnostic marker

Question 19

once a hormone arrives at a target cell, what can it do

Answer 19

-alter plasma membrae permeability of membrane potential by opening or closing ion channels
-stimulates synthesis of proteins or regulatory molecules
-activate or deactivate enzyme systems
-induce secretory activity
-stimulate mitosis