Lecture 1: Into and Overview (Bolsor) Flashcards
which 2 organs have greatest control on extracellular pH? How?
lungs via elimination/retention of CO2
kidneys via reabsorption or secretion of H+ or HCO3
Main functions of the kidney
1) removal of wastes
2) maintaining body fluid/electrolyte/acid-base balance
what 3 systems control water balance, extracellular fluid osmolality and blood pressure?
CNS, Cardiovascular, and renal
where is ADH released?
anterior pituitary gland
increased venous volume –> ADH secretion?
decreases
decreased plasma osmolality —> ADH release
decreases
decreased ADH –> water excretion
increases
Which is faster in it’s response to pH change: respiratory or renal system?
respiratory (but renal is usually needed for full compensation)
what hormone controls sodium reabsorption by the kidneys? Where is it released?
aldosterone (adrenal gland)
how do kidneys regulate blood pressure?
via regulation of extracellular water and electrolytes
urea
a metabolic waste product that is important in the maintenance of the intrarenal medullary concentration gradient
renin
released in response to reduced NaCl delivery to the macula densa. Catalyzes the formation of angiotensin II in the lungs, which then elicits the release of aldosterone from the adrenal cortex to increase Na reabsorption
aldosterone fx in kidneys
stimulates sodium reabsorption
common markers of renal failure
elevated metabolic waste products, such as urea, creatinine, bilirubin, and uric acid
erythropoetin
renal hormone that stimulates erythrocyte production by bone marrow
how are kidneys influential in communication?
urine can carry pheromones
three renal capillary beds
1) glomerular
2) peritubular
3) vasa recta
glomerular capillary bed
- specifically for filtration
- afferent and efferent arterioles within the glomerulus
- high BP forces solutes out of the blood
peritubular capillary bed
- for absorption
- arises from efferent arterioles that drain the glomerulus
- operates under low pressure
- absorbs solutes and water from the tubules
vasa recta capillary bed
- long, thin walled looping arterioles that follow the loop of Henle
- serve juxtamedullary nephrons
what receptors detect decreased plasma volume and signal production of ADH?
atrial receptors
increased renin –> angiotensin II
increases
increased angiotensin II —> aldosterone
increases (see p. 8 diagram in scavma notes)
Levels of multiscale systems physiology:
subcellular processes –> cellular processes –> tissue –> organ –> whole body –> behavior –> population. Each step influences the next. Physiology influences behavior
initiation of hormonal cascade by renin ultimately stimulates which hormone?
aldosterone
nephron
functional subunit of the kidney. Filtrates and reabsorbs arterial plasma components.
Bowman’s capsule
where plasma filtration occurs within a nephron. Always located in the renal cortex
how does age effect #/size of nephrons?
As you get older, nephrons get fewer in number but larger in size
proximal tubule
first part of nephron attached to the Bowman’s capsule
Flow from arcuate artery to bladder through the nephron (10 steps)
arcuate artery –> afferent arterioles –> Bowman’s capsule –> proximal tubule –> loop of Henle –> distal tubule –> collecting duct –> renal pelvis –> ureters –> bladder
What occurs in the afferent arterioles in kidney?
small molecules pass across the glomerular capillary epithelium into the Bowman’s capsule
when does “fluid” become “filtrate” in the kidney?
when it passes into the Bowman’s capsule
what happens in loop of Henle?
filtrate becomes more concentrated
what happens in distal tubule of kidney?
sodium and water are removed and returned to the circulation
primary site of action of ADH in the kidney
collecting ducts. Causes water reabsorption from tubular fluid
juxtaglomerular apparatus
regulates renal blood flow and glomerular filtration rate. Formed when thick ascending limb of loop of Henle loops around to touch the vascular elements supplying the glomerular capillaries.
macula densa
darkly staining band of cells in the thick ascending limb. Contain sodium sensing mechanisms that allow the kidney to regulate sodium balance by controlling blood flow through the glomerulus
long or short loops of Henle more likely to be involved in urinary concentrating mechs?
Long
3 types of cells in collecting ducts
1) Principal cells
2) Intercalated cells (type A)
3) Intercalated cells (type B)
Principal cells
present in collecting ducts. Where ADH and aldosterone act to modify salt and H2O balance
Type A intercalated cells
A stands for acid. Eliminate excess acid in collecting duct in case of acidemia
Type B intercalated cells
B stands for base. Present in collecting ducts. Secrete base into the urine in case of alkalemia
What area of the kidney are glomeruli ALWAYS located in? ***
the cortex
Which structures of the nephron lie in the medulla?
collecting ducts, loop of Henle
What structures of nephron lie in the cortex?
Glomerulus, proximal/distal tubules, part of the collecting ducts
how does fluid osmolality change from outer cortex to inner medulla in the kidney?
osmolality increases as you move towards inner medulla. Cortex = isotonic
thicker medulla –> ability to concentrate urine
increases
xeric definition
something that needs very little water
which groups of animals have loops of Henle in their nephrons?
Mammals and birds
Which groups of animals have a renal portal system?
birds, reptiles, amphibians
which groups of animals have a peritubular capillary network?
mammals only
Which animals have salt glands?
birds and reptiles
which animal groups excrete uric acid?
birds and reptiles
Which species use “number of nephrons filtering” to regulate GFR?
birds, reptiles, amphibians
Which group of animals uses “net filtration pressure” to regulate GFR?
mammals
fx of salt glands
allows animals to excrete excess salt that kidneys alone could not accomplish
how do salt glands and kidneys change in size with an increased salt load?
salt glands increase in size, kidneys don’t change
NaCl concentration in salt glands vs. kidneys
salt glands maintain constant NaCl concentration, while NaCl concentration varies in the kidney
Composition of outflow in salt glands vs. kidneys
Salt glands –> almost exclusively NaCl
kidneys –> NaCl, K, other ions and inorganic solutes
which has higher flow rate: salt glands or kidneys?
salt glands (2-fold higher)
vascular beds (primarily afferent and efferent arterioles) are control elements of circulation in the kidney
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