Chapter 20 Flashcards
Explain how the countercurrent multiplier in the loop of Henle is the key to the regulation of urine concentration.
- Transfers solutes by active transport (ascending limb) into the medulla
- Results in greater ECF osmolarities
What does the vasa recta do in the renal countercurrent multiplier?
removes water
what does the osmolarity of urine represent?
how much water is excreted in the urine
what does low osmolarity represent?
high water
what does high osmolarity represent?
low water
What does the medullary interstitial osmolarity allow?
allows urine to be concentrated
Fluid in descending loop of Henle _________________ to the medulla.
loses water by osmosis
Cells in thick portion of the ascending limb of the loop are impermeable to water and ______________________.
actively transport Na+ out of the lumen into the medulla
Fluid leaving loop of Henle is _____ dilute than fluid entering.
more
Describe what happens in the distal nephron.
- water permeability is under control of hormones
- Permeable to water, filtrate becomes concentrated
What does the collecting duct do?
can reabsorb additional solute, filtrate can become even more dilute
Map in detail the reflex pathway through which vasopressin (aka ADH) controls water reabsorption in the kidney.
look on whiteboard
Diagram the cellular mechanism of action of vasopressin on principal cells.
What does vasopressin cause?
insertion of water pores into the apical membrane –> makes collecting duct epithelium permeable to water
Map the homeostatic responses to salt ingestion.
look at whiteboard
Diagram the cellular mechanism of aldosterone action at principal cells.
look at whiteboard
Map the renin-angiotensin-aldosterone system (RAAS), including all the responses initiated by ANG II and aldosterone.
look at whiteboard
Describe the release of natriuretic peptides and their effects on sodium and water reabsorption.
whiteboard
Diagram the appropriate homeostatic compensations for different combinations of volume and osmolarity disturbances.
whiteboard
Compare and contrast the three mechanisms by which the body copes with minute-to-minute changes in pH.
1) Buffers –> Moderate changes in pH by combining with or releasing H+
- include proteins, phosphate ions, and
HCO3-
2) Lungs –> Ventilation can compensate for pH disturbances
3) Kidneys –> buffers urine
- Proximal tubule secretes H+ and
reabsorbs HCO3-
- Distal nephron can secrete or reabsorb
H+ and HCO3- to regulate pH of
extracellular fluid
Diagram the reflex pathways and cellular mechanisms involved in respiratory compensation of pH changes.
whiteboard
Diagram the mechanisms by which the kidneys compensate for pH changes.
whiteboard
what is the normal pH of plasma?
7.38 - 7.42
Describe acidosis.
Neurons become less excitable –> CNS depression
Describe alkalosis.
Neurons become hyperexcitable –> severe can lead to muscle tetanus
Describe a respiratory acidosis disturbance.
Hypoventilation –> PCO2 increases –> pH decreases
Describe a respiratory alkalosis disturbance.
Hypoventilation –> PCO2 decreases –> pH increases
Describe a metabolic acidosis disturbance.
Dietary and metabolic input of H+ exceeds excretion –> pH decreases
Describe a metabolic alkalosis disturbance.
Loss of H+ through excessive vomiting or excessive ingestion of bicarbonate-containing antacids –> pH increases
