CH24 P2

By what method are solutes and water reabsorbed across the apical surface of the PCT?

symport with Na+

Know how solutes and water are transported across the basal surface of the PCT.

K+/Cl- symport

What other things are secreted and reabsorbed in the PCT?

reabsorbed HCO3-

secrete:

H+

toxins

drugs

Besides electrolytes, what else is reabsorbed in the PCT?

water

nearly all nutrients

vitamins

numerous electrolytes

How much of the water that enter the PCT is reabsorbed?

65%

Understand how obligatory water reabsorption occurs in the PCT.

1. solute reabsorption creates an osmotic gradient

2. H2O drawn through aquaporins

In the descending and ascending LOH know if solutes and water are secreted or reabsorbed.

Descending LOH

• H2O reabsorbed ; solutes secreted

Ascending LOH

• solutes reabsorbed ; not permeable to H2O

How does the concentration of the filtrate change as it moves through the descending LOH?

tubular fluid gets more concentrated at bottom of loop

How does the concentration of the filtrate change as it moves through the ascending LOH?

tubular fluid gets less concentrated at top of loop

Know what methods are used to secrete and reabsorb solutes across the apical surface of the DCT.

Na+/K+

Na+/H+

Know what methods are used to secrete and reabsorb solutes across the basal surface of the DCT.

symport

• Na+/HCO3-

antiport

• Na+/K+

What will be secreted and reabsorbed in the collecting duct?

Na+ and HCO3- reabsorbed

K+ and H+ secreted

Understand how principal cells and intercalated cells will allow for secretion and reabsorption in the collecting duct.

Principal cells

• Have receptors for ADH and aldosterone

• Water only reabsorbed if ADH is present

Intercalated cells

• Type A

  • secrete H+

  • reabsorb HCO3-

• Type B

  • secrete HCO3-

  • reabsorb H+

Pathway of Urine Flow – Be able to trace the pathway of urine flow.

collecting duct → papillary duct → minor calyx → major calyx → renal pelvis → ureter → urinary bladder

What occurs when aldosterone is released?

aquaporins allow for H2O to be reabsorbed

What causes the release of ANP?

increase blood volume and BP

How does ANP release effect ADH and aldosterone?

decrease ADH and aldosterone

What effects will this have?

decrease ADH

• decrease thirst

• increase urine output

decrease aldosterone

• decrease Na+ reabsorption

• decrease K+ and H+ secretion

Understand how countercurrent exchange increases solute concentration in the interstitial fluid.

makes the tubular fluid concentrated at the bottom of the loop

What type of tissue lines the ureters?

transitional epithelium

What allows the urine to move through the ureters?

peristalsis

What type of tissue lines the urinary bladder?

transitional epithelium

What is the trigone?

triggers urination when bladder fills

helps funnel urine to urethra

What is the role of the detrusor muscle?

contraction compressed bladder to release urine

Why are the rugae in the bladder important?

increase surface area

What prevents the contraction of the detrusor muscle during urine storage?

efferent sympathetic impulses

Is the internal urethral sphincter open or closed when urine is being stored?

closed

Where is the micturition center located?

pons

Understand the effect that increasing parasympathetic activity and decreasing sympathetic activity will have on the bladder.

detrusor muscle contracts

internal urethral sphincter relaxes

What causes the internal urethral sphincter to relax? What kind of muscle comprises this sphincter?

decrease sympathetic activity

smooth muscle

What allows for the external sphincter to relax? What kind of muscle comprises this sphincter?

Decrease somatic motor stimulation

skeletal muscle

Capsular Hydrostatic Pressure

pressure in the capsular space that opposes filtration

Glomerular Colloid Osmotic Pressure

osmotic pressure in the blood that opposes filtration

Glomerular Hydrostatic Pressure

BP in the glomerulus that drives filtration

Net Filtration Pressure

helps determine Glomerular Filtration Rate (GFR)

Tubular Reabsorption

allows us to recover some components from the filtrate

Tubular Secretion

allows us to eliminate things