Chapter 17- Physiology of the Kidneys

Functions of Kidneys

volume of blood plasma, wastes, electrolytes, pH, erythropoietin

where is urine made

kidney nephrons

where does urine drain into after being made?

renal pelvis

after the renal pelvis where does urine go?

ureter then urinary bladder and urethra

how is urine transported

peristalsis

Two distinct regions of the kidney

renal cortex and renal medulla

Each pyramid of the renal medula drains into

minor—> major calyx—> renal pelvis

Nephron

functional unit of the kidney that consists of small tubules and associated with blood vessels

How many nephrons are in each kidney

more than a million

What surrounds the glomerulus?

GLomerular (Bowman’s) capsule

The surrounding of the golmerulus does what

forms renal corpuscle

What is the fluid path of nephron tubules?

glomerula capsule —> proximal convoluted tubule —> descending/ascending limbs of loop of henle —> distal convulted tubule —> collecting duct —> minor calyx

What capillaries are found in kidneys

fenestrated

Filtrate

fluid entering capsule

Barriers to glomerular filtration

capillary fenestrae, basement membrane, podocytes with pedicles

reabsorption

return of filtered molecules to blood

How much water is filtered/day

180L

How much water becomes urine

1-2L

Minimum urine output

400mL/day

where does reabsorption happen?

85% in proximal tubules and descending loop of Henle

What is the procees of active transport for kidneys?

Na+ pumped out of filtrate into blood creates a gradient for osmosis

What are found on apical side of tubule cells

tight junctions and microvilli

How is Na+ entered and pumped out in active transport?

Na+ enters passively and is pumped out basally

How does passive transport happen in kidneys?

Cl- follows Na+ into interstital space and water follows both into capillaries

How much salt and water is reabsored in proximal tubules?

65%

How mich water is reabsored in descending limb of loop of henle?

20%

How much water is later regulated by ADH in nephron?

15%

What is the specifications of the collecting duct?

impermeable to NaCl, but permeable to water

When does water leave ?

if interstitial space is hypertonic

What is inserted depending on ADH?

aquaporins

What is the proccess of adh?

ADH binds collecting duct —> cAMP —> protein kinase —> aquaporin fuses with membrane

What happens if there is no ADH?

aquaporins removed and no water reabsorption

Renal clearance

removing substances from lood

Steps of renal clearnace

filtration, reabsorption, secretion

Filtration

starts the process o

Reabsoprtion

returns useful stuff, decreases clearance

Secretion

moves substances into tubules, increases clearance