BIO 431 Exam 4 Questions with
Verified Answers
Outer lining/Protection of the Kidneys - ANSWER--Kidneys are outside of the
peritoneal cavity. This means it is retroperitoneal.
-Instead of serous membranes, kidneys will be protected by layers of fat.
-4 layers, from inner to outer:
1. Fibrous (CT) capsule
2. Perinephric fat
3. Renal Fascia
4. Paranephric fat
Path of Blood Flow To and Away from Kidneys - ANSWER-Aorta → Renal Artery →
Segmental artery → Interlobar artery → Arcuate artery → Cortical radiate (or
interlobular) artery → Afferent arteriole → Glomerulus (capillaries) → Efferent
arteriole → Peritubular capillaries or vasa recta → Cortical radiate vein → Arcuate
vein → INterlobar vein → Renal vein → IVC
Difference between Peritubular Capillaries And Vasa Recta - ANSWER-Peritubular
capillaries go with the convulated tubule seciton but vasa recta go along the length of
the nephron loop/loop of Henle
Nephron Tubule Components (in order) - ANSWER-Glomerular (Bowman's) capsule
Proximal convoluted tubule (PCT)
Nephron loop (loop of Henle)
Descending limb → Ascending limb
Distal convoluted tubule (DCT)
Multiple nephron tubules drain into Collecting Duct (CD): Collecting duct is not part of
the nephron
Two Types of Nephrons - ANSWER-1. Cortical
-Located mostly in cortex
-85%
2. Juxtamedullary
-Located at junction between cortex + medulla
-Long loops extend deep into medulla (cortical nephrons are not like this)
-Vasa recta association
Nephron Blood Vessel Components - ANSWER-Afferent arteriole
Glomerular capillaries (glomerulus)
Efferent arteriole
Peritubular capillaries
Vasa recta (if juxtamedullary nephron)
,List of Post-Nephron Structures (Also flow of filtrate/urine out of the nephron) -
ANSWER--Collecting duct
-Papillary duct
-Minor calyx
-Major calyx: Receives urine from many minor calyces
-Renal pelvis: Receives urine from a few major calyces
-Ureter
-Bladder
-Urethra
At what point is the fluid considered urine and not filtrate? - ANSWER--Once the
filtrate drains into the minor calyx from the papillary duct, it is considered urine.
-At this point, there is no way of modifying the chemical composition or volume that
comes out of the papillary duct.
Full Flow of Urine - ANSWER-1. Capsular space/Capsule
2. PCT
3. Descending limb of nephron loop
4. Ascendiong limb of nephron loop
5. DCT
6. Collecting tubules (to get filtrate from other nephrons)
7. Collecting duct
8. Papillary duct
9. Minor calyx
10. Major calyx
11. Renal pelvis
12. Ureter
13. Bladder
14. Urethra
Ureter (with histology) - ANSWER--Smooth muscle contractions propel urine into
bladder (and further away from the kidneys
-3 layers (inner to outer):
>Mucosa: Transitional epithelium and lamina propia (loose areolar CT)
>Muscularis (smooth muscle): Inner longitudinal layer and outer circular layer
>Adventitia
Layers of the Bladder Wall - ANSWER-1. Mucosa: Transitional epithelium + lamina
propria
2. Submucosa
3. Muscularis: Smooth muscle layers
>Detrusor muscle: urine expulsion. Provides powerful contractions that help propel
urine down to urethra.
4. Adventitia
Trigone - ANSWER--Triangle of 2 Ureteral openings + 1 Urethral opening
-Smoother mucosa and lacks rugae observed in other regions of the bladder wall
Urethra Anatomy - ANSWER-LINING
, -Mucosa: Transitional → Stratified squamous.* Lamina propria with mucous glands.
>URethra will transition to a stratified squamous epithelium as it gets closer to the
exterior of the body because there is more friction there
-Muscularis: Smooth muscle
SPHINCTERS
-Internal urethral sphincter: Involuntary smooth muscle at base of the bladder
-External urethral sphincter: Voluntary skeletal muscle at the urogenital diaphragm.
Urogenital diaphragm is the border between inside and outside
External urethral orifice
Male and Female Urethra Differences - ANSWER--Length: Male is 7-8" and Female
is 1-2" (Urine has a longer distance to travel in males.)
-Males have three segments to the urethra. Prostatic → Membranous/Intermediate
(at the urogenital diaphragm) → Penile/Spongy
Micturition Reflex - ANSWER--Micturition means urination
-Stretch receptors in bladder wall
-Afferents neurons can travel to spinal cord
-Afferent neurons can travel to brain (perception of pressure)
> specifically the Micturition Center in the pons
PARASYMPATHETIC motor neurons (ANS with no conscious control)
1. Contraction of detrusor muscle
2. Relaxation of internal urethral sphincter (to allow urine to flow down)
SOMATIC motor neurons (voluntary/conscious control):
>Relaxation of external urethral sphincter: This sphincter contracts when it's not
ready to urinate and relax when it is ready or appropriate.
3 General Processes of Urine Formation - ANSWER-1. Glomerular filtration
-Water + solutes from glomerulus into glomerular capsule
-Renal corpuscle = glomerular capillaries + capsule
2. Reabsorption
-Movement from tubule lumen back into blood (peritubular capillaries)
-Reclaim everything the body needs to keep
99% of filtrate is reabsorbed ( 70% of filtrate is reabsorbed in the PCT). Urine is the
1% result of what was ultimately filtered at the glomerulus.
3. Secretion
-Movement from the blood (peritubular capillaries) or cells lining the tubule into the
tubule lumen
-Selectively add to the urine: elimination of undesirables + excesses
Three Major Renal Processes (repeat of the slide before) - ANSWER-1. Glomerular
filtration: The movement of substances from the blood within the glomerulus into the
capsular space
Verified Answers
Outer lining/Protection of the Kidneys - ANSWER--Kidneys are outside of the
peritoneal cavity. This means it is retroperitoneal.
-Instead of serous membranes, kidneys will be protected by layers of fat.
-4 layers, from inner to outer:
1. Fibrous (CT) capsule
2. Perinephric fat
3. Renal Fascia
4. Paranephric fat
Path of Blood Flow To and Away from Kidneys - ANSWER-Aorta → Renal Artery →
Segmental artery → Interlobar artery → Arcuate artery → Cortical radiate (or
interlobular) artery → Afferent arteriole → Glomerulus (capillaries) → Efferent
arteriole → Peritubular capillaries or vasa recta → Cortical radiate vein → Arcuate
vein → INterlobar vein → Renal vein → IVC
Difference between Peritubular Capillaries And Vasa Recta - ANSWER-Peritubular
capillaries go with the convulated tubule seciton but vasa recta go along the length of
the nephron loop/loop of Henle
Nephron Tubule Components (in order) - ANSWER-Glomerular (Bowman's) capsule
Proximal convoluted tubule (PCT)
Nephron loop (loop of Henle)
Descending limb → Ascending limb
Distal convoluted tubule (DCT)
Multiple nephron tubules drain into Collecting Duct (CD): Collecting duct is not part of
the nephron
Two Types of Nephrons - ANSWER-1. Cortical
-Located mostly in cortex
-85%
2. Juxtamedullary
-Located at junction between cortex + medulla
-Long loops extend deep into medulla (cortical nephrons are not like this)
-Vasa recta association
Nephron Blood Vessel Components - ANSWER-Afferent arteriole
Glomerular capillaries (glomerulus)
Efferent arteriole
Peritubular capillaries
Vasa recta (if juxtamedullary nephron)
,List of Post-Nephron Structures (Also flow of filtrate/urine out of the nephron) -
ANSWER--Collecting duct
-Papillary duct
-Minor calyx
-Major calyx: Receives urine from many minor calyces
-Renal pelvis: Receives urine from a few major calyces
-Ureter
-Bladder
-Urethra
At what point is the fluid considered urine and not filtrate? - ANSWER--Once the
filtrate drains into the minor calyx from the papillary duct, it is considered urine.
-At this point, there is no way of modifying the chemical composition or volume that
comes out of the papillary duct.
Full Flow of Urine - ANSWER-1. Capsular space/Capsule
2. PCT
3. Descending limb of nephron loop
4. Ascendiong limb of nephron loop
5. DCT
6. Collecting tubules (to get filtrate from other nephrons)
7. Collecting duct
8. Papillary duct
9. Minor calyx
10. Major calyx
11. Renal pelvis
12. Ureter
13. Bladder
14. Urethra
Ureter (with histology) - ANSWER--Smooth muscle contractions propel urine into
bladder (and further away from the kidneys
-3 layers (inner to outer):
>Mucosa: Transitional epithelium and lamina propia (loose areolar CT)
>Muscularis (smooth muscle): Inner longitudinal layer and outer circular layer
>Adventitia
Layers of the Bladder Wall - ANSWER-1. Mucosa: Transitional epithelium + lamina
propria
2. Submucosa
3. Muscularis: Smooth muscle layers
>Detrusor muscle: urine expulsion. Provides powerful contractions that help propel
urine down to urethra.
4. Adventitia
Trigone - ANSWER--Triangle of 2 Ureteral openings + 1 Urethral opening
-Smoother mucosa and lacks rugae observed in other regions of the bladder wall
Urethra Anatomy - ANSWER-LINING
, -Mucosa: Transitional → Stratified squamous.* Lamina propria with mucous glands.
>URethra will transition to a stratified squamous epithelium as it gets closer to the
exterior of the body because there is more friction there
-Muscularis: Smooth muscle
SPHINCTERS
-Internal urethral sphincter: Involuntary smooth muscle at base of the bladder
-External urethral sphincter: Voluntary skeletal muscle at the urogenital diaphragm.
Urogenital diaphragm is the border between inside and outside
External urethral orifice
Male and Female Urethra Differences - ANSWER--Length: Male is 7-8" and Female
is 1-2" (Urine has a longer distance to travel in males.)
-Males have three segments to the urethra. Prostatic → Membranous/Intermediate
(at the urogenital diaphragm) → Penile/Spongy
Micturition Reflex - ANSWER--Micturition means urination
-Stretch receptors in bladder wall
-Afferents neurons can travel to spinal cord
-Afferent neurons can travel to brain (perception of pressure)
> specifically the Micturition Center in the pons
PARASYMPATHETIC motor neurons (ANS with no conscious control)
1. Contraction of detrusor muscle
2. Relaxation of internal urethral sphincter (to allow urine to flow down)
SOMATIC motor neurons (voluntary/conscious control):
>Relaxation of external urethral sphincter: This sphincter contracts when it's not
ready to urinate and relax when it is ready or appropriate.
3 General Processes of Urine Formation - ANSWER-1. Glomerular filtration
-Water + solutes from glomerulus into glomerular capsule
-Renal corpuscle = glomerular capillaries + capsule
2. Reabsorption
-Movement from tubule lumen back into blood (peritubular capillaries)
-Reclaim everything the body needs to keep
99% of filtrate is reabsorbed ( 70% of filtrate is reabsorbed in the PCT). Urine is the
1% result of what was ultimately filtered at the glomerulus.
3. Secretion
-Movement from the blood (peritubular capillaries) or cells lining the tubule into the
tubule lumen
-Selectively add to the urine: elimination of undesirables + excesses
Three Major Renal Processes (repeat of the slide before) - ANSWER-1. Glomerular
filtration: The movement of substances from the blood within the glomerulus into the
capsular space
