Human Anatomy and Physiology : Excretory Physiology

Study concepts, example questions & explanations for Human Anatomy and Physiology

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Example Questions

Example Question #11 : Excretory Physiology

What is the main purpose of the vasa recta?

Possible Answers:

Secretes the majority of the  and  ions into the filtrate

Maintains countercurrent multiplication to prevent disregulation in the concentration gradients set up in the renal medulla

Provides the nephron with oxygen-rich blood

Maintains appropriate temperature in the renal medulla to allow for regular blood flow

Reabsorbs the majority of the solute from the filtrate

Correct answer:

Maintains countercurrent multiplication to prevent disregulation in the concentration gradients set up in the renal medulla

Explanation:

The vasa recta wind around the loop of Henle and maintain a countercurrent multiplication to prevent any disregulation or washout of the concentration gradient that has been set up in the renal medulla.  Without this gradient, the nephron would be unable to concentrate filtrate.  Since the vasa recta carry venous blood, it's oxygen concentration is low and thus needs to go through the pulmonary circuit to pick up more oxygen.

Example Question #12 : Excretory Physiology

Which of the following is the most concentrated part of the nephron?

Possible Answers:

Thick ascending loop of Henle

Thin descending loop of Henle

Distal convoluted tubule

Proximal convoluted tublue

Collecting duct

Correct answer:

Thin descending loop of Henle

Explanation:

Thin descending loop of Henle is the most concentrated part of the nephron. As you progress up and down the nephron, the closer the nephron is to the medulla, the more concentrated it is. This ability is due to the increases absorption of water and the inability to reabsorb solute at this level. 

The other mentioned parts of the nephron are permeable to solute and some water and thus are not as concentrated as the thin descending loop of Henle.

Example Question #13 : Excretory Physiology

If the efferent arteriole becomes constricted, what is likely to occur in the nephron? 

Possible Answers:

The increased osmotic pressure will elevate glomerular filtration rate

Fluid backup will cause the nephron to rupture

The increased hydrostatic pressure will elevate glomerular filtration rate

Glomerular filtration rate will decrease due to a loss in blood pressure

Glomerular filtration rate will remain the same

Correct answer:

The increased hydrostatic pressure will elevate glomerular filtration rate

Explanation:

The efferent arteriole carries blood away from the glomerulus, and so if it is constricted, the blood pressure behind it will increase.  The raise in blood pressure will result in an increase in hydrostatic pressure, pushing additional fluid through the glomerulus i.e elevated glomerular filtration rate. While high hydrostatic pressure does cause damage to the nephron, the nephron rupturing is too extreme of a statement and requires assumptions that are not necessarily valid.

Example Question #14 : Excretory Physiology

The release of renin ultimately results in the stimulation of which gland?

Possible Answers:

Anterior pituitary gland

Thyroid gland

Adrenal cortex

Adrenal medulla

Correct answer:

Adrenal cortex

Explanation:

Renin is a hormone released by granular cells in the juxtaglomerular apparatus, near the nephron glomerulus. These cells monitor the pressure of the filtrate in the distal convoluted tubule. The release of renin will stimulate a cascade of angiotensin I and II. Angiotensin II will ultimately stimulate the adrenal cortex to release aldosterone and increase sodium reabsorption and potassium excretion from the filtrate, leading to water retention.

Example Question #2 : Help With Raas Physiology

Which of the following directly stimulates the release of aldosterone?

Possible Answers:

Angiotensin II

Vasopressin

Adrenocorticotropic hormone

Renin

Angiotensinogen

Correct answer:

Angiotensin II

Explanation:

Aldosterone is a steroid hormone that is released from the adrenal cortex. The function of aldosterone is to increase reabsorption of sodium ions from the distal tubule. Increased sodium ion concentration in the blood then causes the diffusion of water from the nephron into the circulatory system, preventing water loss due to excretion and increasing blood pressure and volume)

Release of aldosterone is mediated by the renin-angiotensin system (RAS). When juxtaglomerular cells detect low blood pressure, they release renin. Renin travels to the liver, where there angiotensinogen is produced, and cleaves angiotensinogen to produce angiotensin I. Angiotensin I then travels to the lungs, where angiotensin converting enzyme (ACE) cleaves it to produce angiotensin II. Angiotensin II then travels to the adrenal cortex to stimulate release of aldosterone into the blood.

Adrenocorticotropic hormone is secreted by the anterior pituitary and acts on the adrenal cortex to stimulate release of cortisol and cortisone, but does not affect aldosterone release. Vasopressin is released by the posterior pituitary and helps the body to retain water; it is not related to aldosterone release.

Example Question #3 : Help With Raas Physiology

Which of the following is not an effect of angiotensin II?

Possible Answers:

Indirectly increases blood volume via the action of antidiuretic hormone

Stimiulates  antiporters to increase reabsorption in the proximal convoluted tubule

Dilutes the urine in order to rid the body of excess fluid

Vasoconstricts the afferent and efferent arterioles to maintain glomerular filtration rate

Promotes the effects of aldosterone to further increase reabsorption

Correct answer:

Dilutes the urine in order to rid the body of excess fluid

Explanation:

Angiotensin II is a major influence on the kidney's function when the body needs to retain fluid - it works in tandem with antidiuretic hormone and aldosterone to accomplish this.  Angiotensin II will also act upon the afferent and efferent arterioles in order to control the glomerular filtration rate and stimulates reabsorption to ensure that the body is keeping necessary solutes/molecules.  Diluting the filtrate in the nephron is the opposite effect that angiotensin has on the kidney.

Example Question #4 : Help With Raas Physiology

Too much of which of the following substances would cause chronic hypertension (high blood pressure)?

Possible Answers:

Nitric oxide

Prostacyclin

Brain natriuretic peptide

Atrial natriuretic peptide

Angiotensin II

Correct answer:

Angiotensin II

Explanation:

Angiotensin II (part of the RAAS) works in the body to cause vasoconstriction in an effort to raise blood pressure. Too much of this substance will cause hypertension, another name for elevated blood pressure. Nitric oxide and prostacyclin work to vasodilate and lower blood pressure. Atrial natriuretic peptide and brain natriuretic peptide are released by the body to lower blood pressure in volume overloaded states.

Example Question #1 : Help With Kidney Physiology

Which of the following is not considered to be a function of the kidney?

Possible Answers:

Conversion of angiotensinogen to angiotensin I

Thermoregulation

Regulation of blood osmolarity

Stimulation of red blood cell production

Maintaining fluid levels in the body

Correct answer:

Thermoregulation

Explanation:

The human kidney has many functions, all of which are important for sustaining life.  The kidney controls blood osmolarity by filtering, reabsorbing, and secreting various ions found throughout the body.  The kidney controls fluid volume in the body by this same mechanism.  Additionally, the kidney produces erythropoietin and renin which stimulate the production of red blood cells and convert angiotensinogen to angiotensin I, respectively. 

Example Question #2 : Help With Kidney Physiology

Which of the following is the outermost layer of the kidney?

Possible Answers:

Renal medulla

Renal cortex

Renal sinus

Renal capsule

Renal pyramid

Correct answer:

Renal capsule

Explanation:

The renal capsule is the outermost structure of the kidney.  It is the fibrous connective tissue kidney structure that directly surrounds the renal cortex, and is surrounded by a layer of adipose tissue that protects the kidney from trauma.  The renal pyramids, renal sinus, and renal medulla are located deep within the kidney.

Example Question #3 : Help With Kidney Physiology

Which of the following kidney structures is the connection point between the bladder and the kidney itself?

Possible Answers:

Renal pelvis

Renal medulla

Urethra

Collecting duct

Ureter

Correct answer:

Ureter

Explanation:

The urine made within the kidney drains out from the renal pelvis and down the ureter to ultimately be stored in the bladder.

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