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60 Cards in this Set

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nitrogenous wastes

urea
uric acid
creatinine


kidney functions


excrete nitrogenous wastes


regulate blood volume


regulate blood pressure


regulate blood chemical


stabilize pH


convert vitamin D into active form

regulate the rate of filtration and blood pressure

macula densa


granular cells

macula densa

in the DCT, contain osmoreceptors that monitor solute concentration and flow rate of filtrate

granular cells

smooth muscle cells in the afferent arteriole, act as mechanoreceptors to monitor BP, synthesize and secrete renin

renin

hormone that

nephron renal processes

glomerular filtration


tubular reabsorption


tubular secretion


excretion

glomerular filtration

plasma filtered from the glomerulus into Bowman's capsule; solutes and hydrostatic pressure forces fluid through the filtration membrane; blood cells and plasma proteins too large to enter filtrate

glomerular capillary BP (55 mmHg)

result of BP pushing on the inside of the capillary wall

plasma-colloid osmotic pressure (30 mmHg)

due to retention of plasma proteins in the blood of glomerulus; concentration of water is higher in Bowman's capsule because proteins are absent there and water tends to return to glomerulus by osmosis

Bowman's capsule hydrostatic pressure (15 mmHg)

tend to move fluid from Bowman's capsule into the glomerulus

glomerular net filtration pressure

glomerular BP - (plasma-colloid osmotic pressure + Bowman's capsule hydrostatic pressure)

GFR efficiency

higher pressure bc afferent larger than efferent arteriole


number of nephrons ↑ surface area


permeability of capillary pores

GFR too high

needed substances cannot be reabsorbed quickly enough and are lost in the urine

GFR too low

everything is reabsorbed, including wastes that are normally disposed of

GFR mechanisms of control

renal autoregulation (intrinsic control)
sympathetic NS (extrinsic control)
hormones (renin-angiotensin-aldosterone system)

renal autoregulation (intrinsic control; short term)

regulates the GFR by factors within the kidneys and normally prevents inappropriate changes in the GFR by myogenic mechanism and tubuloglomerular feedback mechanism

myogenic mechanism

type of renal autoregulation that is controlled by arteriole smooth muscle cells and responds to changes in pressure in the renal blood vessels by constricting the afferent arteriole if pressure is too high, resulting in lower GFR

tubuloglomerular feedback mechanism

type of renal autoregulation that is controlled by macula densa cells in the JGA and senses changes in flow rate in the nephron's tubular component so that the release of vasoactive chemicals would be stimulated if flow rate is too high, resulting in vasoconstriction of afferent arterioles

sympathetic NS (extrinsic control; long term)

overrides autoregulatory mechanism when blood volume drops


stimulates renin-angiotensin-aldosterone system

renin-angiotensin-aldosterone system

triggers ↓ stretch of granular cells


stimulates granular cells by activating macula densa cells


directs stimulation of granular cells via β₁-adrenergic receptors


promotes ↑ systemic BP and volume

angiotensin II

causes systemic arteriole vasoconstriction


stimulates adrenal cortex to release aldosterone

granular cells

releases renin that acts on angiotensinogen to make angiotensin I, which converts to angiotensin II

tubular reabsorption

selective transfer of substances needed by the body from the filtrate back into the peritubular capillaries

transepithelial transport

by this method a reabsorbed substance must cross the tubule wall, enter the interstitial fluid, and pass through the wall of the peritubular capillaries, entering the blood

luminal membrane and a basolateral membrane

membranes of the epithelial cells of the nephron tubule

Na⁺ diffuses through tubule cells at luminal membrane


then actively transported by Na/K pump at basolateral membrane

how sodium reabsorption occur at the tubules

proximal tubule

where 67% of Na⁺ reabsorption occur at a constant rate

loop of Henle

reabsorption of Na⁺ here produces varying concentrations and volumes of urine

distal tubule

reabsorption of Na⁺ here is variable depending on needs of body and level of aldosterone

aldosterone

this hormone increases Na⁺ absorption in the DCT and collecting ducts

insert more Na⁺ channels in the luminal membrane


insert more Na/K pumps in basolateral membrane

what aldosterone can do to promote Na⁺ absorption

atrial natriuretic peptide (ANP)

this hormone inhibits Na⁺ reabsorption which decreases blood volume and lowers BP by acting directly on collecting ducts, inhibit renin pathway, and dilate afferent arteriole to trigger ↑ GFR which ↓ water and sodium reabsorption

reabsorption by proximal convoluted tubule cells

cells that drives reabsorption of the following:


water by osmosis, aided by aquoporins


anions follow by diffusion down electrochemical gradient


glucose and amino acids by secondary active transport

proximal tubule and loop of Henle

80% of water reabsorption is obligatory in these areas and occurs by osmosis without control

distal tubule and collecting duct

20% of water reabsorption is facultative in these areas and based on the secretion of ADH, depending on body's needs

ADH

hormone that works on tubule cells through a cyclic AMP mechanism (secondary active transport) to reabsorb 99% of the water in the filtrate

concentrated

what ADH causes urine to become

glucose and amino acids

minerals that are reabsorbed by secondary active transport and cotransported with sodium on the luminal membrane

transport maximum

this reflects the number of carriers in the renal tubules available and exists for nearly every substance that is actively reabsorbed; when the carriers are saturated, excess of that substance is excreted

urea, creatinine, uric acid, excess K⁺, other nitrogenous waste

substances that lack carriers, are not lipid soluble, and are too large to pass through membrane pores

tubular secretion

selective process by which substances from the peritubular capillaries enter the lumen of the nephron tubule in order to speed up the elimination of substances from the blood (instead of waiting for blood to get back to glomerulus)

distal tubule

where excess potassium secretion occurs

aldosterone

hormone that stimulates tubular cells to secrete potassium if plasma potassium levels are too high

1. chemical buffers in blood act within seconds


2. respiratory center in brain stem acts within 1-3 min


3. renal mechanisms need hours to days to ∆ pH

regulation of acid-base balance (concentration of H⁺)

renal mechanisms of acid-base balance

reabsorb/generate new bicarbonate ions if acidosis (lose H⁺)


excrete bicarbonate ions if alkalosis (gain H⁺)

phosphate buffer system

when excreted H⁺ binds to buffers in the urine

response to acidosis

type A cells generate bicarbonate ions and add them to blood


an equal amount of H⁺ are added to the urine


H⁺ binds with buffers in the filtrate (monohydrogen phosphate)

response to alkalosis

type B cells exhibit bicarbonate ion secretion


type B cells reclaim H⁺ and acidify the blood

vertical osmotic gradient

the large variation in reabsorption in the interstitial fluid of the renal medulla (300-1200 mosm/liter)

countercurrent

the movement of opposite directions of filtrate through the ascending and descending limbs of the loop of Henle, also applies to the flow of blood through the vasa recta

countercurrent multiplier

refers to the ability to increase the osmolarity of the interstitial fluid

descending loop of Henle

is relatively impermeable to solutes


is permeable to water

ascending loop of Henle

is permeable to solutes


is impermeable to water, doesn't follow Na⁺ by osmosis


actively transports NaCl out of tubular lumen

interstitial fluid

ascending loop of Henle produces this that becomes hypertonic to the descending limb in order to attract water by osmossis for reabsorption

countercurrent exchanger

the hairpin structure of the vasa recta that allows the blood of the vasa recta to equilibrate with the interstitial fluid

high glucose levels


alcohol


caffeine/drugs

osmotic diuretics

high glucose level diuretic

osmotic diuretic that carries water out with the glucose

alcohol diuretic

osmotic diuretic that inhibits the release of ADH

caffeine and most diuretic drugs

osmotic diuretics that inhibit sodium ion reabsorption