Week 11

Question 1

What are the three main regions of the kidney?

Answer 1

Cortex, Medulla (both contain nephrons), and Pelvis.

Question 2

List four key functions of the kidneys.

Answer 2

1. Activate Vitamin D
2. Maintain water/salt and acid/base balance
3. Produce renin and erythropoietin
4. Filter blood to remove toxins, wastes, and excess ions

Question 3

What are ureters and their function?

Answer 3

Paired tubes that transport urine from the kidneys to the bladder.

Question 4

Where is the bladder located and what is its main function?

Answer 4

In the pelvic cavity; it stores urine until excretion.

Question 5

What triggers the urge to urinate, and what muscles are involved?

Answer 5

Stretch receptors in the bladder trigger the urge at ~300–400 mL; detrusor muscle contracts, internal sphincter relaxes involuntarily, and external sphincter relaxes voluntarily.

Question 6

Name two clinical conditions related to the bladder.

Answer 6

Urinary tract infections (UTIs) and incontinence.

Question 7

What is the difference between the internal and external urethral sphincters?

Answer 7

Internal is involuntary; external is under voluntary control.

Question 8

What is the nephron and what is its main function?

Answer 8

The nephron is the structural and functional unit of the kidney, responsible for filtering blood and producing urine.

Question 9

What are the glomerulus and glomerular capsule, and what do they form together?

Answer 9

The glomerulus is a porous ball of capillaries; the glomerular capsule is a cup-shaped structure surrounding it. Together, they form the renal corpuscle.

Question 10

What is the primary role of the proximal convoluted tubule?

Answer 10

Reabsorption of filtrate back into the bloodstream.

Question 11

What is the function of collecting ducts in the nephron?

Answer 11

They receive urine from nephrons and deliver it to the renal pelvis.

Question 12

Where are cortical nephrons located and what is their role?

Answer 12

Located in the kidney cortex; they perform most of the kidney’s regulatory functions.

Question 13

What is the key function of juxtamedullary nephrons?

Answer 13

Located in the cortex and medulla; they help the kidney produce concentrated urine.

Question 14

What are the two capillary beds associated with each nephron and their functions?

Answer 14

• Glomerular capillaries: produce filtrate
• Peritubular capillaries: reclaim filtrate back into the blood

Question 15

What are the three major processes of urine formation in the nephron?

Answer 15

Glomerular filtration
Tubular reabsorption
Tubular secretion

Question 16

What happens during glomerular filtration?

Answer 16

Fluids and small solutes (e.g., water, glucose, amino acids) are passively filtered from blood into the glomerular capsule, while proteins and blood cells are excluded.

Question 17

What substances are reabsorbed during tubular reabsorption and where does it occur?

Answer 17

Glucose, amino acids, water (70%), vitamins, salts (Na⁺, Cl⁻, K⁺, Ca²⁺, etc.); occurs in the PCT, loop of Henle, DCT, and collecting ducts.

Question 18

Describe the functions of the descending and ascending limbs of the loop of Henle

Answer 18

Descending limb: Permeable to water, concentrates filtrate.
Ascending limb: Impermeable to water, reabsorbs solutes (Na⁺, Cl⁻).

Question 19

What hormones influence reabsorption in the distal convoluted tubule and collecting ducts?

Answer 19

• ADH: Water reabsorption
• Aldosterone: Sodium and potassium
• ANP: Sodium excretion
• PTH: Calcium and phosphate balance

Question 20

What is tubular secretion and why is it important?

Answer 20

Selective removal of substances (H⁺, K⁺, ammonia, creatinine) into the tubule to regulate pH and eliminate waste; occurs in PCT and DCT.

Question 21

Describe the two phases of micturition.

Answer 21

• Storage Phase: Bladder fills; detrusor relaxed; sphincters contracted; sympathetic control.
• Voiding Phase: Bladder contracts; internal sphincter relaxes; external sphincter voluntarily relaxed; parasympathetic and somatic control.

Question 22

What are some clinical conditions related to micturition?

Answer 22

• Urinary incontinence (stress, urge, overflow, functional)
• Urinary retention
• Neurogenic bladder
• Overactive bladder

Question 23

What are the two main fluid compartments in the body?

Answer 23

• Intracellular fluid (ICF)
• Extracellular fluid (ECF) = interstitial fluid + plasma

Question 24

What triggers the thirst mechanism and ADH release?

Answer 24

• Rising plasma osmolarity stimulates osmoreceptors in the hypothalamus → triggers thirst and ADH release.
• Drinking water and stomach stretch inhibit thirst and ADH.

Question 25

How does ADH regulate water balance?

Answer 25

- High ADH → aquaporins in collecting ducts → water reabsorbed → concentrated urine - Low ADH → water lost in urine → dilute urine

Question 26

How is sodium balance tied to water balance and blood pressure?

Answer 26

- Water follows sodium (osmosis) - Sodium determines ECF volume, influencing blood pressure and blood volume

Question 27

What is the role of the Renin-Angiotensin-Aldosterone System (RAS)?

Answer 27

- Renin → angiotensin I → angiotensin II (via ACE) - Angiotensin II → vasoconstriction & aldosterone release - Aldosterone → Na⁺ reabsorption → water follows → increased blood volume and pressure

Question 28

What stimulates renin release from the juxtaglomerular apparatus?

Answer 28

- Sympathetic stimulation - Decreased blood pressure or decreased blood volume - Reduced stretch of afferent arterioles

Question 29

What are the three mechanisms of acid-base balance regulation?

Answer 29

1. Chemical buffer systems (immediate) 2. Respiratory regulation (minutes) 3. Renal regulation (hours to days)

Question 30

Name and describe the three major chemical buffer systems.

Answer 30

- Protein buffer system: Most abundant, buffers both acids and bases - Phosphate buffer system: Buffers ICF and urine - Carbonic acid-bicarbonate buffer system: Major ECF buffer, especially in the blood

Question 31

How does the respiratory system regulate pH?

Answer 31

- Removes CO₂ → reduces H⁺ → raises pH - Chemoreceptors in the medulla, carotid, and aortic bodies detect pH changes

Question 32

How do the kidneys regulate acid-base balance?

Answer 32

- Excrete H⁺ and reclaim HCO₃⁻ - In acidosis: increase H⁺ excretion and bicarbonate reabsorption - In alkalosis: reduce H⁺ excretion and reabsorb less bicarbonate