Anatomy

Question 1

Renal blood supply

Answer 1

• 22% of cardiac output
• unique blood flow
• 2 capillary beds
  1) glomerular
  2) peritubular

Question 2

Glomerular capillaries

Answer 2

• HIGH hydrostatic pressure (60mm)
• causes rapid fluid FILTRATION
• encased in the Bowman’s capsule

Question 3

Peritubular capillaries

Answer 3

• LOWER hydrostatic pressure (13mm)

- allows for rapid fluid REABSORPTION

Question 4

Nephron

Answer 4

• functional unit of the kidney
• 2 diff nephron structures/areas
  1) Cortical nephron
  2) Juxtamedullary nephron

-can NOT regenerate new nephrons

Question 5

Juxtamedullary nephron

Answer 5

• significantly longer Loop of Henle
• penetrates deeper into medulla
• 20-30% of the nephrons
• surrounded by specialized peritubular capillaries (VASA RECTA)

Question 6

Fluid filtered from glomerular capillaries

Answer 6

Bowman’s Capsule -> proximal tubule -> loop of Henle -> distal tubule -> connecting tubule -> collecting duct -> renal pelvis

Question 7

Cortical nephron

Answer 7

• short loops of Henle
• only barely penetrate into the medulla
• 70-80% of the nephrons
• surrounded by peritubular capillaries

Question 8

Anatomy of urinary bladder

Answer 8

Smooth muscle chamber with 2 main parts

1) Body - primary part where urine collects
2) Neck - attaches to urethra

Question 9

Detrusor muscle

Answer 9

-responsible for CONTRACTION OF BLADDER
-smooth m of bladder
-fibers are intertwined
-low-resistance to electrical impulses btwn muscle cells
(whole bladder contracts at once)
-contraction - increases pressure by 40-60 times
-major step in emptying bladder

Question 10

Trigone

Answer 10

• on POST wall of bladder
• ureters enter at UPPER trigone
• Surface = smooth mucosa (contrast to the folded rugae of the rest of the bladder mucosa

Question 11

Ureters

Answer 11

• obliquely enters the bladder through the DETRUSOR MUSCLE
• penetrates 1-2 cm through detrusor and mucosa
• the tone of the muscle shuts down the ureters (prevents BACKFLOW of urine)

Question 12

Bladder neck (posterior urethra)

Answer 12

• composed of DETRUSOR M and ELASTIC tissue
• muscle here is the INTERNAL SPHINCTER - prevents emptying of the bladder until pressure rises above the critical threshold

Question 13

Urethra

Answer 13

Passes through UROGENITAL DIAPHRAGM

Question 14

External sphincter muscle

Answer 14

• smooth muscle

- under voluntary control (can consciously contract to prevent urine; MEN)

Question 15

Innervation of urinary bladder

Answer 15

1) Pudendal N
2) Sympathetic Innervation
3) Pelvic N’s
4) sensory and motor nerve fibers

Question 16

Pudendal N (urinary bladder)

Answer 16

• SOMATIC

- Innervate the EXTERNAL bladder sphincter

Question 17

Sympathetic Inn (urinary bladder)

Answer 17

• through HYPOGASTRIC n’s (L2)

- stimulate blood supply to the bladder

Question 18

Pelvic N’s (urinary bladder)

Answer 18

-through SACRAL PLEXUS (s2,s3)

Question 19

Sensory nerve fibers (urinary bladder)

and Motor nerve fibers

Answer 19

Sensory - detect STRETCH of bladder wall

Motor - PARASYMP; innervate DETRUSOR M

Question 20

Urine Flow

Answer 20

Nephron -> Collecting ducts -> Renal calyces -> Ureters -> Bladder

-CD’s to RC’s causes peristaltic contractions (in renal pelvis and ureters)

Question 21

Ureters

Answer 21

• Innervated by SYMP (dec contraction) and PARASYMP (inc contraction) nerves
• smooth visceral m (contraction of ureters)

Question 22

Ureterorenal Reflex

Answer 22

• ureters contain a lot of PAIN fibers
• severe pain (ie, kidney stone) =
  1) reflex constriction occurs
  2) symp reflex occurs back to kidney
  3) constrict renal arterioles
  4) dec’s flow of fluid into the kidney with a blocked ureter

Question 23

Micturition

Answer 23

• SENSORY STRETCH RECEPTORS initiated as bladder fills
• Self-regenerative (initial contracture of the detrusor m causes further activation of the stretch receptors)

-Urination can be facilitated or inhibited by centers in the PONS and CEREBRAL CORTEX (have final control of micturition)

Question 24

As micturition reflex INCREASES…

Answer 24

• reflex passes through the PUDENDAL N’s to the EXTERNAL sphincter
• AUTONOMIC REFLEX

Question 25

Voluntary urination

Answer 25

• contraction of ABS
• increase pressure in bladder
• increase urine that enters bladder neck
• stretch receptors initiate micturition reflex
• empty bladder