mod 8 Urinary Tract and renal physiology Flashcards
• 2b. The kidneys are retroperitoneal – what does this mean?
• The retroperitoneum is the part of the abdominal cavity which lies
between the posterior parietal peritoneum and anterior to the
transversalis fascia
• Organs are retroperitoneal if they have peritoneum on their anterior
side only
. Describe the micturition reflex
• When the bladder volume reaches about
400mL (in an adult), the urge to void
becomes so great that micturition can no
longer be delayed
• Visceral afferent impulses from the bladder
wall receptors act via spinal interneurons to
excite parasympathetic neurons and inhibit
sympathetic and somatic neurons
• Three simultaneous events
1. Contraction of detrusor muscle by activation
of parasympathetic fibres and inhibition of
sympathetic fibres
2. Relaxation and opening of internal urethral
sphincter by activation of parasympathetic
fibres and inhibition of sympathetic fibres
3. Relaxation and opening of external urethral
sphincter by inhibition of the somatic
efferents
Bladder contracts and internal and external
sphincters open voiding of urine
• 5. In terms of body water compartments, which contains the greatest
percentage of body water?
• A. plasma
• B. tissue fluid (extracellular interstitial fluid)
• C. intracellular fluid
• D. the abdominal cavity
• E. whole blood
• C. intracellular fluid
- The apex of the renal pyramid is called the
- A. major calyx
- B. minor calyx
- C. renal papilla
- D. renal pelvis
- E. ureter
• C. renal papilla
• 7. The renal pyramid is
• A. the innermost layer of kidney tissue
• B. the conical shaped structure in the renal medulla
• C. an internal cavity lined by the fibrous capsule and located in the
area of the hilus
• D. a large branch of the renal pelvis
• E. a knot of capillaries in the renal corpuscle
• B. the conical shaped structure in the renal medulla
• 8. Which of the following is correct concerning the
location of the kidneys?
• A. the right kidney is usually higher than the left one
• B. they are both located behind the parietal
peritoneum
• C. their upper borders are about at the level of the
third lumbar vertebra
• D. They are against the anterior wall of the abdominal
cavity
• E. none of the above
• B. they are both located behind the parietal
peritoneum
- Major calyces are
• A. large branches of the renal pelvis
• B. expanded ends of nephrons
• C. basic functional layers of the kidney
• D. conical-shaped structures in the renal medulla
• E. the expanded ends of renal pyramids
A. large branches of the renal pelvis
- The thirst centre is located in the
- A. thalamus
- B. hypothalamus
- C. midbrain
- D. pons
- E. medulla oblongata
• B. hypothalamus
- The external urethral sphincter is formed by
• A. smooth muscle in the wall of the bladder
• B. smooth muscle in the wall of the urethra
• C. skeletal muscle of the urogenital diaphragm
• D. skeletal muscle in the wall of the bladder
• E. smooth and skeletal muscle in the wall of the
bladder
• D. skeletal muscle in the wall of the bladder
- Which of the following statements concerning the
micturition reflex is false?
• A. relaxation of the external sphincter occurs under
voluntary control
• B. interneurons in the spinal cord relay sensory
information to the cerebral cortex
• C. increased afferent impulses from stretch receptors
in the urinary bladder facilitate parasympathetic motor
neurons in the spinal cord
• D. the internal sphincter relaxes when the external
sphincter is relaxed
• E. the micturition reflex is controlled by neurons in the
lumbar region of the spinal cord
• E. the micturition reflex is controlled by neurons in the
lumbar region of the spinal cord ( neurons in the
sacral region of the spinal cord are involved)
• 13. Which of the following correctly lists the order of
structures through which urine flows after its
formation in the nephron?
• A. calyx, renal pelvis, ureter, urinary bladder, urethra
• B. renal pelvis, calyx, ureter, urinary bladder, urethra
• C. renal pelvis, calyx, urethra, ureter, urinary bladder
• D. renal pelvis, calyx, urinary bladder, ureter, urethra
• E. glomerular capsule, PCT, nephron loop (LoH), DCT,
collecting duct
• A. calyx, renal pelvis, ureter, urinary bladder, urethra
• 14. The detrusor muscle
• A. moves urine through the ureters
• B. compresses the urinary bladder and expels urine through the
urethra
• C. functions as the internal urinary sphincter
• D. functions as the external urinary sphincter
• E. is located in the renal pelvis
B. compresses the urinary bladder and expels urine through the
urethra
• 15. The micturition reflex is voluntarily controlled by
the
• A. person controlling contraction and relaxation of the
pyloric sphincter valve
• B. sympathetic impulses stimulating the internal
urethral sphincter valve
• C. cerebral cortex stimulating or inhibiting the
external urethral sphincter valve
• D. voluntary contractions of inhibition of the prostate
gland
• E. spinal cord
C. cerebral cortex stimulating or inhibiting the
external urethral sphincter valve
• 16. Define detrusor muscle
• Smooth muscle wall of the urinary bladder
• When relaxed allows urine storage
• Contraction compresses the bladder contents and expels urine from
the bladder
• 17. Distinguish between the internal and external urethral sphincters
• The internal sphincter is a smooth muscle ring and is
continuous with the detrusor muscle
• Under autonomic control by the sympathetic and
parasympathetic systems
• Sympathetic activation contraction urine storage
• Parasympathetic activation relaxation and
micturition
• The external sphincter is part of the urogenital
diaphragm
• Composed of skeletal muscle
• Voluntary (somatic motor) control
• Contraction allows urine storage
• Relaxation allows micturition
• 1. Which of the following represents the correct order
of anatomical structures in the nephron?
• A. glomerulus, proximal convoluted tubules (PCTs),
loop of Henle (LoH), distal convoluted tubules (DCTs)
• B. PCTs, LoH, DCTs, glomerulus
• C. glomerulus, DCTs, LoH, PCTs
• D. DCTs, glomerulus, PCTs, LoH
• E. glomerulus, LoH, PCTs, DCTS
• A. glomerulus, proximal convoluted tubules (PCTs),
loop of Henle (LoH), distal convoluted tubules (DCTs)
• 2) Which structure(s) are responsible for collecting the primary filtrate as it is formed? • a) the proximal tubules • b) the bladder • c) the glomerulus • d) the Bowman’s capsules • e) the collecting ducts
d) the Bowman’s capsules (glomerular capsules)
• 3) The Tmax for glucose in the renal tubules is
approximately 300mg/100ml of filtrate.
• What does this mean?
• a) any value lower than this will likely ensure no
glucose is found in urine
• b) any value higher than this will likely ensure no
glucose is found in urine
• c) any value lower than this will likely cause glucose
to be left in urine
• d) any value higher than this will likely cause glucose
to be left in urine
• e) options a) and d) are both correct
e) options a) and d) are both correct
4. What would you not expect to find in the primary filtrate? • a) glucose • b) urea • c) haemoglobin • d) albumin • e) neither c) or d)
• e) neither c) or d)
5) What is the net filtration pressure, assuming that:
(all values in mmHg)
• 1. glomerular capillary hydrostatic pressure = 54
• 2. plasma COP = 32
• 3. hydrostatic pressure in Bowman’s capsule = 14
• a) 54 mmHg
• b) 32 mmHg
• c) 22 mmHg
• d) 14 mmHg
• e) 8 mmHg
• Forces driving water and solutes out of plasma in
glomerular capillaries through filtration membrane into
Bowman’s (glomerular)capsule:
• Glomerular hydrostatic pressure (HPgc) = glomerular
blood pressure
• Bowman’s capsule osmotic pressure (OPcs): healthy
urine has negligible protein, so that OP in Bowman’s
capsule ≈0
• Forces opposing movement of water and solutes from
the glomerular capillaries into Bowman’s capsule:
• Colloid osmotic (oncotic) pressure of blood in the
glomerular capillaries (OPgc)
• Capsular hydrostatic pressure (HPcs) exerted by fluid in
Bowman’s capsule
• NFP = (HPgc+ OPcs)-(HPcs+ OPgc)
• Where HPgc = glomerular blood hydrostatic pressure
• OPgc = blood colloid osmotic (oncotic) pressure
• HPcs = capsular hydrostatic pressure
• Opcs = osmotic pressure of fluid in Bowman’s capsule
• NFP = (54 + 0)– (32 + 14)mmHg
• = 54 – 46 mmHg
• = 8 mmHg
• 6) Presuming the same as the previous question but informed that filtrate COP is 1 mmHg, what would net pressure now be? • a) 33 mmHg • b) 9 mmHg • c) 7 mmHg • d) 13 mmHg • e) 39 mmHg
- b) 9 mmHg
- NFP = (HPgc+ OPcs)-(HPcs+ OPgc)
- = (54 + 1)– (32 + 14)mmHg
- = 55 – 46 mmHg
- = 9 mmHg
• 7) How much of filtered water is absorbed in the
proximal tubule (known as “obligatory” reuptake)
• a) ~25%
• b) ~50%
• c) ~65%
• d) ~ 95%
• e) option a) would be correct if the term
“facultative” was used in place of “obligatory” since
the uptake in the proximal tubule is facultative
• c) ~65%
• 8) The renal juxtaglomerular apparatus: what do
macula densa cells do?
• a) release renin
• b) release angiotensin
• c) release factors which constrict or dilate the
associated afferent arterioles
• d) ensure that associated efferent arterioles are
normally severely constricted (i.e. essentially closed)
• e) induce leakiness in glomerular capillaries
c) release factors which constrict or dilate the
associated afferent arterioles
- Most filtered water is reabsorbed in the kidney:
which segment of a nephron achieves the bulk of this
reabsorption, and how is this achieved?
- ~65% of filtered water is reabsorbed in the PCT
* Water follows sodium by osmosis
• 14. Diabetes mellitus refers to the production of sweet urine – explain
how and why this occurs.
• What other, related renal symptom occurs with respect to urine
formation?
• Saturation of the Na+-Glucose transporters in the
proximal convoluted tubule i.e. Tm is exceeded
• By leaving glucose in the urine it exerts an osmotic
pull on water, holding more water in the tubule
system
• Uncontrolled DM patients produce large volumes of
“sweet” urine (diuresis)
• 15. The kidneys can excrete a very dilute urine or a comparatively
concentrated urine – give figures in mOsm to these extremes, and
describe how each is arrived at.
• Establishment and maintenance of the osmotic
medullary gradient
• and
• The action of ADH
• 19. The kidneys activate or produce all but one of the following – which is the odd one out? • a) vit D • b) erythropoietin • c) antidiuretic hormone • d) renin • e) the original statement is incorrect – the kidneys produce or activate all of the above
• c) antidiuretic hormone
- Presuming that the transport maximum for glucose
carriers in the proximal tubule of the kidney is
300mg/100ml filtrate, what would happen if the
filtrate contained 350 mg glucose/100ml
• a) the excess glucose will be taken up the distal tubule,
and urine volume will remain unchanged
• b) excess glucose will be taken up the collecting duct
and bladder, at the expense of water, meaning a
hypotonic diuresis will occur
• c) the excess glucose will remain in the urine, occupy
space, and therefore reduce water loss, reducing the
volume of urine lost
• d) the excess glucose will remain in the urine, attract
water osmotically, meaning a diuresis will occur
d) the excess glucose will remain in the urine, attract
water osmotically, meaning a diuresis will occur
- Approximately what maximum tissue osmolarity is
created by the long loops of Henle, and it what tissue
is this created?
• a) ~120 mOsmols,……in the medulla
• b) ~1200 mOsmols,……in the cortex
• c) ~2100 mOsmols,……in both the cortex and medulla
• d) ~1200 mOsmols,……in the medulla
• e) ~ 300 mOsmols, ……in both the cortex and medulla
• d) ~1200 mOsmols,……in the medulla
• 22. Why don’t we suddenly produce a large volume
of urine when our blood pressure rises during
exercise, for example?
• a) in fact we do, but the excess urine is reabsorbed
by the bladder
• b) the myogenic response reduces flow through the
afferent glomerular arteriole
• c) sodium pumps in the proximal tubule are inhibited
by high blood pressure
• d) sympathetic nerves reduce blood flow to the
kidneys
• e) both b) and d) can be involved
e) both b) and d) can be involved
- What is the role of angiotensin converting enzyme (ACE)
- a) to activate conversion of renin to angiotensin I
- b) to convert angiotensin I to angiotensin II
- c) to activate conversion of renin to angiotensin II
- d) to convert angiotensin I to renin
- e) to convert angiotensin II to aldosterone
• b) to convert angiotensin I to angiotensin II
- What stimulates the release of aldosterone?
- a) low plasma Na+
- b) drop in arterial BP
- c) high plasma K+
- d) angiotensin II
- e) all of the above
• e) all of the above
25. What stimulates release of renin? • a) low BP • b) low GFR • c) sympathetic activity • d) all of the above • e) none of the above, renin is always present and simply needs to be activated
d) all of the above
• 26. What specific properties of the renal vasa recta
facilitate it’s role in maintaining low [NaCl] in the
medulla
• a) slow moving blood
• b) the presence of a vascular loop that, essentially,
follows the loop of Henle
• c) high COP
• d) all of the above
• e) all of the above, but only if the original statement
stated that the vasa recta helped maintain high [NaCl]
in the medulla
• e) all of the above, but only if the original statement
stated that the vasa recta helped maintain high [NaCl]
in the medulla
• 27. This hormone directly inhibits sodium and water retention by the
kidneys
• a) aldosterone
• b) renin
• c) atrial natriuretic peptide
• d) angiotensin
• e) options a) and b) both serve this function
• c) atrial natriuretic peptide
- Cells of the juxtaglomerular apparatus are in direct contact with….
- a) the proximal convoluted tubule
- b) the loop of Henle
- c) the collecting ducts
- d) the distal convoluted tubule
- e) the vasa recta
• d) the distal convoluted tubule
