ch 11.9- excretory system Flashcards
excretion
is the filtering out of metabolic wastes from
the body’s fluids and eliminating them as urine.
functions of the kidney
● Regulation of blood pressure
● Regulation of blood pH
● Stimulates the generation of new red blood cells
what are the main processes of the nephron
filtration- filtration of stuff from blood (glomerulus) to bowmans capsule
reabsorption
secretion
excretion
renal corpuscle
comprises the glomerulus and
Bowman’s capsule and is located in the renal cortex.
what happens in the glomerulus
glomerulus, filtration occurs. Blood enters
from the afferent arteriole into the glomerulus, which
acts as a sieve, allowing small substances into the
Bowman’s capsule. Hydrostatic pressure from the
blood is the main force driving filtration in Bowman’s
capsule. The glomerulus exits the Bowman’s capsule
via the efferent arteriole, which forms the peritubular
capillaries and the vasa recta.
where does most of reabsorption occur
in the proximal convoluted tubule through ACTIVE TRANSPORT
distal convoluted tubule
reabsorbs Na+
and Cl-
what does the nephron absorb
Glucose and amino acids are two molecules the
nephron reabsorbs almost completely due to their
importance in the body.
loop of henle
The loop of Henle descends into the medulla and
exhibits selective permeability at each limb. Urea,
waste products, and drugs are secreted into the
nephron by active and passive transport. Surrounding
the loop of Henle is the vasa recta, a network of
capillaries that runs parallel to it.
descending limb of loop of henle
permeable to water. Water is
reabsorbed into the blood as the filtrate travels down
the descending limb, becoming more concentrated.
ascending limb of loop of henle
impermeable to water. As the
filtrate travels up the ascending limb, solutes are
reabsorbed, and the filtrate becomes less
concentrated.
the longer the loop of henle
the more concentrated urine will be
distal convoluted tubule
From the loop of Henle, the filtrate goes to the distal
convoluted tubule. Na+
and Cl-
are reabsorbed
here, with water following passively.
collecting duct
where water passively moves out and concentrates
the urine. The urine travels to the renal pelvis and
then to the ureter.
RAAS
renin angiotensin aldosterone system
juxtaglomerular cells
release renin when blood
pressure is low.
renin
is an enzyme which acts on angiotensinogen
to activate it to the form angiotensin I.
ACE
Another enzyme called angiotensin converting
enzyme (ACE) acts on angiotensin I to convert it to
angiotensin II. Angiotensin II is the active hormone.
angiotensin II
has many effects in the body to
increase blood pressure and volume, including:
● It stimulates aldosterone release from the adrenal gland cortex.
● It increases Na+ reabsorption from the proximal tubule (water follows the salt).
● It is a systemic vasoconstrictor, causing vessels to constrict and thereby increasing total peripheral resistance (TPR).
● It increases thirst: drinking more increases liquid blood volume (and thus TPR).
aldosterone
mineralocorticoid produced by the
adrenal cortex. It increases salt and water
reabsorption and potassium secretion in the distal
tubules and collecting ducts.
ADH
(aka ADH or vasopressin).
Released from the posterior pituitary upon
stimulation from the hypothalamus. Causes
aquaporins to insert into the collecting duct of the
nephron and increases water reabsorption.
ANP
Atrial natriuretic peptide (ANP) is produced by atrial cells in response to atrial distension by increased blood volume and pressure. ANP reduces blood volume and blood pressure. It accomplishes this by:
● Increasing the glomerular filtration rate (GFR),
which is the rate at which the kidneys filter blood.
● Decreasing sodium reabsorption
● Increasing sodium excretion
● Inhibiting renin and the renin angiotensin aldosterone system (RAAS)
osmoregulation of marine/saltwater fish
are hypoosmotic to their
environment. They are less salty than the
surrounding saltwater. Therefore, they’re
constantly losing water to their environment. As a
result, marine fish:
● Constantly drink water
● Rarely urinate
● Secrete accumulated salts through their gills
osmoregulation of freshwater fish
are hyperosmotic to their
environment. They are more salty than the
surrounding freshwater. Therefore, they’re
constantly absorbing too much water. As a result,
freshwater fish:
● Rarely drink water
● Constantly urinate
● Absorb salts through their gills
