EXAM 4 - PNB 2775 UPDATED ACTUAL QUESTIONS AND CORRECT ANSWERS

EXAM 4 - PNB 2775 UPDATED ACTUAL QUESTIONS AND
CORRECT ANSWERS

Question:
1. Urinary system
- Excretes
- Regulates
- Secretes
Answer:
Excretes
- Metabolic end products
- Drugs, and many other exogenous compounds Regulates
- Many essential substances (Na, K, H+, Ca, Mg, Cl, HCO3, HPO4, H2O)
- Osmolarity
- pH
- Arterial BP Secretes
- Secrete renin, erythropoietin, and activates vitamin D

Question:
2. Anatomy of the kidney
Answer:
Cortex (outer area)
- Outer cortical region
- Inner juxtamedullary region Medulla (inner area)
- Renal pyramids (nephrons come together into the tip of the pyramids) Calyces
- Minor: papillae extend (tip of pyramid)
- Major: converge to form pelvis

Question:
3. Anatomy of the nephron
Answer:
- Nephron = Corpuscle + a renal tubule of 50 mm in length
- Consists of a Bowman's capsule, proximal convoluted tubule (PCT), loop of Henle, distal convoluted
tubule (DCT), and collecting duct
- In reality, the corpuscle makes close contact with the loop of Henle but this is not shown in diagrams

Question:
4. Two types of nephrons

,Answer:
Cortical (85%)
- Start in cortex
- Re-absorption, filtering, and secreting
- Peritubular capillaries Juxtamedullary
- Also start in cortex
- Extend deeper into medulla
- Very few
- Vasa recta extend from the peritubular capillaries and surround the loop of Henle
- Osmolarity differences

Question:
5. Excretion formula
- Where does secretion, filtration, and reabsorption happen in the nephron
Answer:
- Excretion = Filtration - Reabsorption + Secretion
- Reabsorption happens throughout the nephron
- Filtration happens only at the capsule
- Secretion happens only at the tubules and collecting duct

Question:
6. Glomerular Filtration Rate (GFR)
Answer:
- Amount of plasma filtered from the glomeruli into Bowman's space per unit time (volume/time)
- The average in an adult human is 125 ml/min, or 180 L/day, meaning a lot of plasma gets reabsorbed
otherwise we would be urinating a lot more
- Plasma can be filtered about 60 times a day
- About 20% of the plasma volume coming in gets filtered into the nephron, the other 80% stays in the
blood, and more than 19% gets reabsorbed, so only less than 1% is actually secreted

Question:
7. Renal corpuscle
Answer:
- Composed of the glomerulus and Bowman's Capsule
- Glomerulus: capillary network
- Bowman's capsule: beginning of tubule (parietal and visceral epithelium)
- Plasma enters in through the afferent arteriole and exits through the efferent arteriole

Question:
8. Filtration barrier
- What gets through and what doesn't?
Answer:
- Made up of fenestrated capillary epithelium, basement membrane (basal lamina), and pores formed by
podocytes
- Because of the fenestration and leaky podocytes, things in plasma (ions, glucose, small nutrients, etc.) get
through while larger things like cells and proteins stay left behind in the blood
- The resulting filtrate is protein-free dialysate of plasma

, Question:
9. Factors that affect GFR
Answer:
Favor
- Ph: glomerular capillary hydrostatic pressure (causes fluid to filter into the lumen)
-- This is the primary mechanism for physiological regulation of GFR Oppose
- Pfluid: Bowman's capsule hydrostatic pressure (increasing fluid buildup in capsule opposes the
hydrostatic pressure)
- Colloid pressure: from proteins left behind in the blood

Question:
10. Formula for net glomerular filtration pressure
Answer:
Net glomerular filtration pressure = Ph - Pfluid - colloid

Question:
11. Variables that affect Ph
Answer:
- Arterial pressure; buffered by auto regulation
- Afferent arteriolar resistance
- Efferent arteriolar resistance
- Dilating the afferent arteriole increases capillary BP, renal flow, and GFR (all increase)

Question:
12. Autoregulation of GFR
Answer:
- Achieved over a wide range of blood pressures to maintain a certain GFR
- This maintains a nearly constant GFR when mean arterial BP is between 80 and 180 mmHg
- Done via myogenic response (blood vessels), tubuloglomerular feedback (juxtaglomerular apparatus),
and hormones and autonomic neurons (renin-angiotensin system)

Question:
13. Myogenic response (autoregulation of GFR)
Answer:
- Similar to autoregulation in other arterioles
- Increased renal BP causes stretch and constriction of afferent arteriole (and vice versa) via MLCK
activation

Question:
14. Tubuloglomerular feedback (TGF)
Answer:
- Paracrine control
- Increased GFR (via increased NaCl sensed by macula densa) --> constriction of afferent arteriole
- The macula densa are from the distal tubule that communicate with the corpuscle to regulate GFR