Mod 4. L26 Flashcards
adrenaline (epinephrine) and noradrenaline (norepinephrine)
catecholamine hormones
synthesized in the adrenal medulla
important for various physiological responses
(glucose availability, heart rate, blood flow, etc)
released during stress
modulate flight or fight responses
increases heart contractions
vasoconstriction (leading to an increase in blood pressure)
relax smooth muscles around the lungs to promote breathing
increase blood sugar levels
adrenal medulla
in adrenal gland
medulla, a core central part of the adrenal gland
produces stress hormones (like epinephrine and norepinephrine)
L32 it is innervated by only the sympathetic system
example of hormone affecting other hormone systems
adrenaline stimulates the release of glucagon and inhibits insulin release
leptin can inhibit insulin secretion
and insulin can also directly reduce the drive for food intake
nephron
functional unit of the mammalian kidney
has 3 main regions:
1) proximal convoluted tubule
2) loop of henle
3) distal convoluted tubule
loop of Henle
part of the nephron
extracts water out of the filtrate, salts are pumped out into the surrounding medium to make it hypertonic relative to the filtrate
establishes concentration gradient for removing more water from the filtrate
collecting duct
part of mammalian kidney
where solutes and water are also exchanged between blood and urine
osmoconformers
animals that do not actively control the osmotic condition of their body fluids and instead conform to the osmorality of the ambient medium
osmoregulators
animals that maintain and internal osmolarity that is relatively constant and can differ from the surrounding medium
glomerulus
a system of tiny capillaries where blood is forced into as it enters the kidney through renal arteries
Bowman’s capsule
as the pressure in the glomerulus is pretty high, some of the fluid (filtrate) in the blood enters a sac (Bowman’s capsule)
the filtrate is made of water, urea and some smaller ions , some of it should be resorbed
hormones acting on nephrons (important for osmoregulation)
ADH (anti-diuretic hormone) from the posterior pituitary gland
and aldosterone
from adrenal cortex
both influence processes in collecting duct of nephrons
ADH (anti-diuretic hormone)
from the posterior pituitary gland
stimulated by dehydration
makes collecting duct more permeable to water = creates more concentrated urine ( due to increase in aquaporins in membrane cells of collecting duct )
High ADH = concentrated urine
Low ADH = Dilute urine
aquaphorins (relation with ADH levels)
allow water to flow in and out of cells
opening aquaporins in collecting duct (increased by ADH increase) = reabsorbing water from urine
ADH decrease = decrease of aquaporins by endocytosis
Aldosterone
steriod hormone secreted by adrenal cortex
regulates solute concentrations in blood and urine
similar to ADH, stimulated by dehydration
acts on receptors in collecting duct
influences re-absorption of Na+ from the urine
net movement of Na+ out of the urine indirectly leads to water movement out of the urine
amount of urine reduced
ADH levels in saltwater versus freshwater environments
freshwater = lower (diluted urine)
saltwater (more dehydrated) = higher (concentrated urine)
