Chapter 24: Renal System and Long-Term Blood Pressure Regulation

GFR has fallen and is now too low. Which of the following is a response that you might expect?

- Vasoconstriction of the efferent arteriole - Vasoconstriction of the afferent arteriole * Vasoconstriction of the efferent arteriole causes blood to back up in the glomerulus, while vasodilation of the afferent arteriole will allow more blood to flow into the glomerulus. Both cause increased GBHP and GFR.

Match each region of the renal tubule to a description of its location and histology: 1. Proximal convoluted tubule 2. Thin segment of nephron loop 3. Thick segment of nephron loop 4. Distal convoluted tubule

1. Located in the cortex; lined by a simple cuboidal epithelium with microvilli 2. Located in the medulla; lined by a simple squamous epithelium 3. Located in the medulla; lined by a simple cuboidal epithelium 4. Located in the cortex, lined by a simple cuboidal epithelium without microvilli

Match each limb of the nephron loop to a description of its permeability: 1. Descending limb 2. Ascending limb

1. Permeable to water but not solutes 2. Permeable to solutes but not water

Arrange the connective tissues coverings of the kidneys from deep to superficial

1. Renal capsule 2. Perirenal fat capsule 3. Renal fascia

Arrange the regions of the male urethra in the order that they would be encountered by a catheter. That is, arrange them from the region opening to the exterior of the body, to the region adjacent to the bladder.

1. Spongy urethra 2. Membranous urethra 3. Prostatic urethra

You are performing an inulin clearance test on a patient in order to determine their GFR. Inulin is being infused such that blood plasma concentration is 0.5 mg/mL. The patient produces urine that has an inulin concentration of 40 mg/mL at a rate of 1.5 mL/min. What is this patient's GFR in mL/min?

120 mL/min * C=UV/P - C is the rate of renal clearance, typically in mL/min - U is the concentration of the substance in the urine - V is the rate of urine formation - P is the concentration of the substance in the blood plasma

If the BCOP is suddenly decreased to 20 mm Hg, while the GBHP and CHP are unaffected, what would the NFP be?

20 mm Hg

Blood enters the glomerulus through which vessel?

Afferent arteriole

Urine is stored within the ___ prior to leaving the body

Bladder

A 22-year-old male arrived at the emergency department one Saturday morning feeling very ill. He had extreme nausea and had vomited several times. He was also complaining of a throbbing headache with faintness and dizzy spells. On physical examination, the patient had a strong odor of alcohol. He admitted that he had become extremely intoxicated the night before. What is the cause of the dizziness and faint feeling in this patient and what should we do?

He has low blood volume, give him IV fluids with dextrose

A 72-year-old male comes to the clinic because he is "not feeling right" and has experienced ankle swelling over the past two weeks. He was being treated for high cholesterol, took a baby aspirin every day, and had some atherosclerosis on a recent CT scan, which the patient received due to a minor automobile accident. There was no injury, but the ER ordered the CT scan because he had some abdominal discomfort around the area of the seat belt. He denied taking any other medications, but then he remembered that the ER doctor had given him a prescription for pain killers. He said he did not fill the prescription because painkillers make him feel weird, so he just takes multiple ibuprofen for pain. The physical exam did not show much except a little edema around the ankles. Ibuprofen acts as a vasoconstrictor of arterioles at higher doses. What do you think is wrong?

Ibuprofen constricts the afferent arteriole, slowing blood flow to the kidneys and other areas of the body

What problem(s) would ensue if proteins larger than 7 nm were filtered into the nephron?

It would be very difficult for them to be reabsorbed and they would cause problems with the loss of urine from the body.

Which of the following is not part of the filtration barrier inside the glomerulus?

Proximal convoluted tubule

Which of the following accurately follows the flow of urine from a renal papilla to the urinary bladder?

Renal papilla, minor calyx, major calyx, renal pelvis ureter, urinary bladder * A minor calyx collects urine from the papilla and then empties into a major calyx. The major calyx empties into the renal pelvis, which is continuous with the ureter, which then carries urine to the urinary bladder.

​A 44-year-old man arrives at the clinic for a follow-up visit. He had very high blood pressure on the previous visit, so he was asked to keep a journal of his blood pressure. The journal revealed that he was hypertensive over 70% of the day, leading to a diagnosis of hypertension. The physician prescribed some medications and advised him to greatly decrease his sodium intake. He stated that he really liked salt and salty foods and asked how necessary it actually is to decrease sodium. Why was the patient asked to reduce his sodium intake?

Sodium forces the body to retain water, thus increasing blood volume and blood pressure *Sodium is an important ion and presents 50% of the solutes within plasma. In the kidney, reabsorption of sodium leads to reabsorption of water, ultimately resulting in blood volume and blood pressure

Is there any other capillary system in the body with two capillary beds in series like those found in the kidney?

The hypothalamic-pituitary blood flow also has two capillary beds in series

Which type of epithelium comprises the mucosa of the urinary bladder? Why is this functionally significant?

The mucosa of the bladder is a transitional epithelium. This type of epithelium readily stretches allowing the bladder to expand as it fills with urine.

Which of the following statements regarding the ureter is false?

The transitional epithelium of the ureter mucosa contracts to move urine by peristalsis * The ureter does move urine via peristalsis, but it is the smooth muscle of its muscularis layer that accomplishes this.

What does the presence of transitional epithelium in the ureter tell you about the function of the ureter?

The ureter does not stretch and hence does not store urine.

Why is the external urethral sphincter composed of skeletal muscle and not smooth muscle, like the internal urinary sphincter?

This allows people to decide when they wish to void urine, because skeletal muscle is under voluntary control.

Urination is the process by which:

Urine is lost from the body

Imagine a genetic condition that impaired the ability of the cells of the proximal convoluted tubule to reabsorb glucose. What would be the physiologic consequence of this disorder?

Valuable glucose would be lost in the urine. Additionally, as the movement of water is the PCT is passive and requires the osmotic gradient created by active reabsorption of ions, proteins, amino acids, vitamins, and glucose, there will be reduces reabsorption of water. This will cause dehydration. So, this person will have difficulty remaining nourished and hydrated

What are the possible consequences of prolonged elevation of GFR?

​Filtrate that moves too quickly through the renal tubules has less available time for reabsorption. Hence, many things that should be reabsorbed, like Na+, Cl-, organic nutrients, etc. may be lost with the urine. Dehydration may also occur as there will be reduced reabsorption of water.