Urinary System Part 1

Question 1

External Structures of the Kidney:

Answer 1

-Kidneys
Retroperitoneal- location
Renal capsule- surrounds each
- Imbedded in mass of fat
Renal fascia- fibrous tissue surrounding the capsule and fat layer that attaches the kidney to posterior abdominal wall
- Hilum- medial indentation for entry/exit blood vessels, nerves, lymph vessels, ureter

Question 2

Structures of the Kidney

Answer 2

• Renal cortex
• Renal medulla
• Renal pyramids
• Renal columns
• Minor calyx
• Major calyx
• Renal pelvis

Question 3

Nephron

Answer 3

Nephron
 1.2 million nephrons per kidney
 Functional unit of the kidney
 3 kinds
 Superficial cortical nephrons
 Extend partially into medulla
 Midcortical nephrons
 Juxtamedullary nephrons
 Extend deep into medulla- urine concentration

Question 4

Nephron- Tubular structure with subunits that contribute to urine formation

Answer 4

• Renal corpuscle
• Proximal convoluted tubule
• Loop of Henle
• Distal convoluted tubule
• Collecting duct

Question 5

Nephron- Tubular structure with subunits that contribute to urine formation:

Answer 5

-Renal corpuscle
Glomerulus- “tuft of capillaries”
Bowman capsule
Mesangial cells-support, contractile, phagocytic, produce vasoactive substances, control flow
Bowman space- Space inside Bowman’s capsule

Question 6

Nephron

Answer 6

• Glomerular filtration membrane (wall of glomerular capillary for filtration)
• • Glomerular endothelium
• • Basement membrane

–Capillary epithelium
Also referred to as podocytes or visceral epithelium
Filtration slits

Question 7

Nephron

Answer 7

Juxtaglomerular apparatus

• Juxtaglomerular cells- around the afferent arteriole where it enters renal corpuscle
• Macula densa- portion of distal convoluted tubule with specialized sodium and chloride sensing cells.

Question 8

Nephron

Answer 8

- Renal tubules
 Proximal tubule
 Loop of Henle
 Distal tubule
 Collecting duct
--- Principal cells-resorb  
Na and H2O, secrete K
--- Intercalated cells- secrete H, bicarbonate, resorb K

Question 9

Structures of the kidney: Blood Vessels

Answer 9

• Renal arteries
• Interlobar arteries
• Arcuate arteries
• Interlobular arteries
• Afferent arterioles
• Glomerular capillaries
• Efferent arterioles
• Peritubular capillaries and vasa recta

Question 10

Ureters

Answer 10

• 30 cm long
• Long, intertwining muscle bundles
• Pass obliquely though posterior aspect of bladder
• Peristaltic activity
• Micturition compresses the lower end of the ureter to avoid urine reflux

Question 11

Bladder

Answer 11

• Detrusor muscle
• Transitional epithelium-barrier to prevent water and solutes moving between urine and blood
• Trigone- between openings ureters and urethra
• Micturition reflex

Question 12

Urethra:

Answer 12

• internal and external sphincters (muscles)
• 3 to 4 cm in females
• 18 to 20 cm in males

Question 13

Renal Blood flow:

Answer 13

 Receive 1000 to -1200 mL of blood per minute

-Glomerular filtration rate (GFR)
1) Plasma vol per unit
time
2) Directly related to
perfusion pressure
in glomerular
capillaries
3)Directly related to
renal blood flow
(RBF)

Question 14

Regulation of Renal Blood Flow:

Answer 14

• Autoregulation
• Try to keep RBF and GFR constant
• Myogenic mechanism
  1) ↓Arterial pressure → ↓ stretch afferent arteriolar SM → arteriole relaxes → increase RBF

2) ↑ Arterial pressure → ↑ stretch afferent arteriolar SM → arteriole contracts → decrease RBF

-Tubuloglomerular feedback
 –Macula densa cells sense flow and sodium and triggers compensatory changes in arteriolar resistance and GFR

Question 15

Regulation of Renal Blood Flow:

Answer 15

Neural regulation
 -Baroreceptor reflex response to Systemic BP
- Sympathetic ANS- NE stimulates
vasoconstriction when systemic BP decreases

Hormones

• Renin- angiotensin systems
• Natriuretic peptides- atrial natriuretic peptide (ANP) from right atrium

Question 16

Renal Blood Flow: Nephron Function

Answer 16

-Glomerular filtration

 The process of forming a protein-free plasma across the glomerular capillaries

 Net filtration pressure
- Glomerular hydrostatic pressure
-Capsular hydrostatic pressure
- Blood oncotic pressure
 
Filtration rate

Question 17

Glomerular Filtration: Nephron Function

Answer 17

• Tubular reabsorption
  -Tubular secretion
  -Excretion
  -Tubular transport
  Proximal tubule
  Loop of Henle and distal tubule
  Glomerulotubular balance- proximal tubule adjusts rate to counter GFR to maintain Na and water balance

Question 18

Tubular reabsorption:

Answer 18

• Movement fluids and solutes from the tubular lumen to the peritubular capillary plasma
• Mechanisms are both active and passive

Question 19

Tubular Secretion:

Answer 19

• transfer of substances from the plasma of peritubular capillary to the tubular lumen
• Not water
• Transport mechanisms are both active and passive

Question 20

Excretion:

Answer 20

-Elimination of urine

Question 21

Tubular Transport:

Answer 21

-General name for movement of ions or water across the tubule membranes

Question 22

Nephron Function- Simultaneous

Concentration and Dilution of Urine

Answer 22

Countercurrent exchange system

• Contributes to production of concentrated urine
• Fluid flows in opposite direction through parallel tubes
• Fluid moves up and down the parallel limbs of the loop of Henle
• The longer the loop, the greater the concentration gradient

Question 23

Concentration and Dilution of Urine:

Answer 23

• Urea
• Catecholamines
• Antidiuretic hormone (ADH)
• Urodilantin
• Natriuretic peptide
• Diuretics

Question 24

Renal Hormones:

Answer 24

• Vitamin D

- Erythropoietin

Question 25

Tests of Renal Function:

Answer 25

``` - Clearance and glomerular filtration rate  Inulin  Creatinine -Clearance and renal blood flow - Blood tests  Plasma creatinine concentration  Plasma cystatin C concentration  Blood urea nitrogen (BUN) ```

Question 26

Tests of Renal Function: Urinalysis

Answer 26

-Urine color -Urine pH -Specific gravity -Urine sediment  RBCs  Casts  Crystals  WBCs

Question 27

Tests of Renal Function: Urinalysis

Answer 27

``` -Urinalysis  Reagent strips (dipsticks)  Glucose  Bilirubin  Urobilinogen  Leukocyte esterase  Nitrates  Ketones  Proteins  RBCs, hemoglobin, and myoglobin ```

Question 28

Aging and Renal Function:

Answer 28

- Decrease in kidney size -Decrease in renal blood flow and GFR -Number of nephrons decrease due to renal vascular and perfusion changes -Glomerular capillaries atrophy -Tubular transport response decreases -Increased bladder symptoms  Urgency, frequency, and nocturia