Chapter 17 - kidneys Flashcards
What 5 things do the kidneys regulate?
a. Volume of blood plasma (affects blood pressure)
b. Wastes
c. Electrolytes
d. pH
e. Secrete erythropoietin
How is urine created and how is it excreted?
Urine made in the kidney nephrons drains into the renal pelvis, then down the ureter to the urinary bladder.
It passes from the bladder through the urethra to exit the body.
How is urine transported?
Using peristalsis
What are the 2 regions of the kidney?
Renal cortex
Renal medulla, made up of renal pyramids and columns
How do renal medulla pyramids drain into the renal pelvis?
Each pyramid drains into a minor calyx → major calyx → renal pelvis.
Functional unit of the kidney?
Nephron
What does the nephron consist of?
small tubules and associated blood vessels
How does blood turn into urine?
Blood is filtered, fluid enters the tubules, is modified, then leaves the tubules as urine
What are the renal blood vessels?
Renal artery →
Interlobar arteries →
Arcuate arteries →
Interlobular arteries →
Afferent arterioles
Glomerulus →
Efferent arterioles →
Peritubular capillaries →
Interlobular veins →
Arcuate veins →
Interlobar veins →
Renal vein
What surrounds glomerulus?
Glomerular (Bowman’s) capsule
glomerulus
What makes up the renal corpuscle?
Glomerular (Bowman’s) capsule
Filtrate from the renal corpuscle passes into what?
proximal convoluted tubule
Nephron tubules:
Fluid passes into the descending and ascending limbs of the _____________
Loop of Henle
Where does fluid pass after the loop of Henle?
The distal convoluted tubule
In nephron tubules, where is the last place fluid passes before it drains into the minor calyx?
the collecting duct
What does it mean for the capillaries of the glomerulus if it has large pores allow water and solutes to leave but not blood cells and plasma proteins?
Capillaries of the glomerulus are fenestrated
Fluid entering the glomerular capsule is called?
Filtrate
In Glomerular Corpuscle, what must the filtrate pass through?
a. Capillary fenestrae
b. Glomerular basement membrane
c. Visceral layer of the glomerular capsule composed of cells called podocytes with extensions called pedicles
return of filtered molecules to the blood?
Reabsorption
What is the obligatory water loss?
A minimum 400 ml must be excreted to rid the body of wastes
______ L of water is filtered per day, but only ___ to ____ L is excreted as urine.
180 L of water is filtered per day, but only 1 to 2 L is excreted as urine.
85% of reabsorption occurs in the?
proximal tubules and descending loop of Henle
What does it mean if the osmolality of filtrate in the glomerular capsule is equal to that of blood plasma?
It is iso osmotic
__________ is actively transported out of the filtrate into the peritubular blood to set up a concentration gradient to drive ________.
Na+ is actively…
…to drive osmosis
Reabsorption in the Proximal Tubule - Active transport (copy paste)
a. Cells of the proximal tubules are joined by tight junctions on the apical side (facing inside the tubule).
b. The apical side also contains microvilli.
c. These cells have a lower Na+ concentration than the filtrate inside the tubule due to Na+/K+ pumps on the basal side of the cells and low permeability to Na+.
d. Na+ from the filtrate diffuses into these cells and is then pumped out the other side.
Reabsorption in the Proximal Tubule - Passive transport (copy paste)
a. The pumping of sodium into the interstitial space attracts negative Cl− out of the filtrate.
b. Water then follows Na+ and Cl− into the tubular cells and the interstitial space.
c. The ions and water diffuse into the peritubular capillaries.
What ion do you actively transport in water reabsorption
Which ions follow?
Na+
Cl- and H2O
heres the rest of the slides - I’ve surrendered
Significance of proximal tubule reabsorption
a. 65% of the salt and water is reabsorbed, but that is still too much filtrate
b. An additional 20% of water is reabsorbed through the descending limb of the Loop of Henle.
Happens continuously and is unregulated
The final 15% of water (~27 L) is absorbed later in the nephron under control of the hormone Anti-Diuretic Hormone (ADH).
Fluid entering loop of Henle is isotonic to extracellular fluids.
Collecting Duct and ADH
Last stop in urine formation
Impermeable to NaCl but permeable to water
a. Also influenced by hypertonicity of interstitial space – water will leave via osmosis if able to
b. Permeability to water depends on the number of aquaporin channels in the cells of the collecting duct
c. Availability of aquaporins determined by ADH (antidiuretic hormone; arginine vasopressin)
ADH binds to receptors on collecting duct cells → cAMP → Protein kinase → Vesicles with aquaporin channels fuse to plasma membrane.
a) Water channels are removed without ADH.
ADH is produced by neurons in the hypothalamus but stored and released from the posterior pituitary gland
a) Release stimulated by an increase in blood osmolality
Transport Processes Affecting Renal Clearance
Kidneys must also remove excess ions and wastes from the blood.
a. Sometimes called renal clearance
b. Filtration in the glomerular capsule begins this process.
c. Reabsorption returns some substances to the blood (decreases renal clearance)
d. Secretion finishes the process when substances are moved from the peritubular capillaries into the tubules. (increases renal clearance)
