Kidney Structure and Function

what is the most important function of the kidney?

homeostatic regulation of fluid and electrolytes

what is one of the 6 areas that the kidney functions in?

regulation of extracellular fluid volume and blood pressure

what is one of the 6 areas that the kidney functions in?

regulation of osmolarity

what is one of the 6 areas that the kidney functions in?

maintenance of ion balance

what is one of the 6 areas that the kidney functions in?

homeostatic regulation of pH

what is one of the 6 areas that the kidney functions in?

excretion of wastes

what is one of the 6 areas that the kidney functions in?

production of hormones

what do the blood vessels of the kidney supply blood to?

nephrons

what percent of nephrons does the outer cortex contain and what are they called?

80%; cortical nephrons

what percent of nephrons does the inner medulla contain and what are they called?

20%; juxtamedullary nephrons

what is the bowman’s capsule the site of?

plasma filtration with glomerulus

what are the bowman’s capsule and glomerulus called together?

renal corpuscle

loop of henle

descending limb and ascending limb

collecting ducts

distal tubules of up to 8 nephrons converge and drain into collecting duct then renal pelvis

distal nephron

distal tubule and collecting ducts

juxtaglomerular apparatus

regulates blood pressure and fluid balance

where does the ascending limb in the juxtaglomerular apparatus pass between?

afferent and efferent arterioles at glomerulus

kidney filtration: where does fluid from blood go?

lumen of nephron

where does kidney filtration occur?

renal corpuscle only

filtrate

filtered plasma

excreted unless reabsorbed

what happens to materials in filtrate during kidney reabsorption?

passed back into blood

with what does kidney reabsorption occur?

peritubular capillaries

where do materials go during kidney secretion?

from blood into lumen of tubule

with what does kidney secretion occur?

peritubular capillaries

what percent of filtrate is reabsorbed by proximal tubules?

70%

filtrate in loop of henle: how much solute is reabsorbed relative to water?

more solute reabsorbed than water

what is the equation for amount of filtrate excreted?

amount filtered - amount reabsorbed + amount secreted

filtration fraction

percent renal flow that filters into tubule

the renal corpuscle contains ___ barriers

filtration

what is glomerular filtration rate (GFR) controlled by?

regulating blood flow through renal arterioles

GFR control: increased resistance in afferent arteriole, ___ GFR

decreases

GFR control: increased resistance in efferent arteriole, ___ GFR

increases

GFR control: decreased resistance in afferent arteriole, ___ GFR

increases

GFR control: decreased resistance in efferent arteriole, ___ GFR

decreases

myogenic response

intrinsic ability of vascular smooth muscle to respond to pressure changes

what is myogenic response similar to?

autoregulation in other systemic arterioles

what do hormones and autonomic neurons also influence?

glomerular filtration rate

how do hormones and autonomic neurons influence GFR?

by changing resistance in arterioles

by altering the filtration coefficient

what kind of control pathway is tubuloglomerular feedback?

local

tobuloglomerular feedback: what influences GFR?

fluid flow through tubule

transepithelial transport

substances cross apical and basolateral membranes of the tubule epithelial cells

what is transepithelial transport also known as?

transcellular transport

paracellular pathway

substances pass through the cell-cell junction between two adjacent cells

what kind of gradients does active transport of Na⁺ create?

electrical

what kind of gradient is created when anions follow the active transport of Na⁺?

osmotic

what happens when H₂O follows active transport of Na⁺?

higher concentration of cations left behind

what is the primary driving force for most renal reabsorption?

active reabsorption of Na⁺

what is the secondary active transport?

symport with Na⁺

what is the passive reabsorption?

urea

what is endocytosis?

plasma proteins

saturation

maximum rate of transport that occurs when all carriers are occupied by substrate

renal threshold

plasma concentration at which a substance first appears in the urine

what is an example of renal threshold?

glucose

what do peritubular capillary pressures favor?

reabsorption

what does it mean if there are healthy concentrations of glucose?

all glucose is reabsorbed

what does it mean when there is excess glucose?

filtered faster than it can be carried

what is the point of saturation?

transport maximum (T_m)

what is renal threshold in terms of glucose concentration?

plasma concentration when glucose appears in urine