214 neural control

Question 1

What is the somatic innervation of the striated muscles of the pelvis?

Answer 1

pudenal nerve

external anal and urethral sphincters, bulbospongiosus, ischiocavernosus, transverse perineal muscles, pelvic diaphragm

Question 2

What are the sympathetic innervations of the pelvis?

Answer 2

hypogastric nerve mostly

colon receives fibers from lumbar colonic nerve

pelvic organs receive innervation from the lumbar colonic nerves

Question 3

What are the parasympathetic innervations of the pelvis?

Answer 3

pelvic nerve (uses ACh)

Question 4

What are the pelvic afferents?

Answer 4

pelvic and pudenal nerves (mostly)

some in the hypogastric nerve

visceral afferents transmit distension information from the bladder, urethra, and colon + pain from viscera

Question 5

What nerves maintain contraction of the internal and external anal sphincter?

Answer 5

internal - contracted by sympathetic nerves

external - contracted by pudenal plexus activity

Question 6

What is the defecation reflex?

Answer 6

distension of rectum initiates reflex –> pelvic nerve afferents transmit signal to spinal cord –> inhibits sympathetic nerves (leads to sphincter relaxation and colonic motility) –> external anal sphincter relaxes by withdrawal of tonic pudenal nerve activity

Question 7

What brainstem responses are associated with the defecation reflex?

Answer 7

valsalva maneuver, maintenance of voluntary control

Question 8

What is the sympathetic and parasympathetic innervation to the detrusor and bladder neck?

Answer 8

sympathetic: hypogastric nerve
parasympathetic: pelvic nerve

Question 9

What is the somatic innervation to the external urethral sphincter and other striated muscles?

Answer 9

pudenal nerve

Question 10

What is the function of the internal urethral sphincter?

Answer 10

to prevent leakage of urine

Question 11

What neurotransmitters contract the detrusor muscle? Relax it?

Answer 11

contract: ACh
relax: NE, NO

Question 12

What neurotransmitters relax the internal urethral sphincter? contract?

Answer 12

relax: NO, ACh
contract: NE

Question 13

What controls the tone of the external urethral sphincter?

Answer 13

resting tone due to tonic pudenal nerve activity

Question 14

What spinal reflex controls continence?

Answer 14

bladder filling promites sphincter contractions and leads to inhibition of the detrusor muscle by the hypogastric nerve (via inhibition of pelvic nerve activity)

leakage of urine into the urethra leads to contraction of the external urethral sphincter

Question 15

What are the spinal reflexes of the mictruition reflex?

Answer 15

bladder distension leads to relaxed external and internal sphincters (mediated by withdrawal of pudenal activity and sympathetic activity respectively)

Question 16

What are the physical events of male sexual arousal?

Answer 16

penile erection (vasodilation in tissue, contraction of striated muscles)

increased arterial blood flow, reduced venous outflow

increased penis volume

Question 17

What nerves/neurotransmitters mediate penile vasodilation?

Answer 17

cavernous nerve, nitric oxide

Question 18

What nerve mediates contraction of penile muscles?

Answer 18

pudenal nerve

Question 19

What physical changes are associated with female arousal?

Answer 19

vaginal lubrication (high in K, low in Na)

clitoral erection (cavernous nerve)
genital vasocongestion

Question 20

What are the physical events of male climax?

Answer 20

fluid release from prostate, seminal vesicle, and ductus deferens into the prostatic urethra

pressure builds and fluid is pushed out (with muscle contraction)

Question 21

What neurotransmitters stimulate glandular secretion during male climax?

Answer 21

ACh and NE

Question 22

Which best describes the role of sympathetic innervation of the urinary system?

a) contracts detrusor muscle
b) relaxes bladder neck
c) promotes micturition
d) promotes continence
e) is synergistic with the parasympathetic innervation

Answer 22

d) promotes continence

Question 23

A woman suffers a pudenal nerve injury from a bicycle accident. What is the most likely dysfunction from this injury?

a) impaired detrusor contractions
b) anal sphincter weakness
c) reduced colonic peristalsis
d) absent bladder fullness sensation

Answer 23

b) anal sphincter weakness

Question 24

Which of the following elements of the defecation process requires input from higher centers of the brain in a healthy person under normal conditions?

a) peristaltic contractions of the sigmoid colon
b) rectal distension
c) rectal peristalsis
d) relaxation of external anal sphincter
e) relaxation of internal anal sphincter

Answer 24

d) relaxation of external anal sphincter

Question 25

A 65 yo man with a longstanding history of BPH has the acute onset of a sensation of urinary urgency followed by urinary incontinence. Which of the following is the most likely mechanism for his urinary leakage?

a) pelvic nerve afferent fibers inhibiting pelvic nerve efferent fibers
b) hypogastric nerve inhibition of detrusor muscle
c) pudenal nerve efferent fiber stimulation of the external sphincter
d) brainstem inhibition of the parasympathetic preganglionic neuron
e) acetylcholine (muscarinic) fibers stimulation of bladder smooth msucle

Answer 25

e) acetylcholine (muscarinic) fibers stimulation of bladder smooth msucle

Question 26

A 51 yo man presented to his physician with a complaint of difficulty maintaining an erection during sexual intercourse. During the history and physical examination, he said he had been a diabetic since he was 8 years old. He had some problems with retinopathy previously, and he was taking an ACE-I, a statin, and insulin injections daily. He has six children, between the ages of 7 and 22 years. His heart and lung sounds were within normal limits. His EKG showed normal sinus rhythm with a rate of 75 bpm. Results of his lab studies included a blood sugar of 120, BUN of 16, serum creatinine of 0.6, cholesterol of 180, hematocrit of 49%, HbA1c of 7. His urine was positive for microalbuminuria but negati ve for glucose. It is likely that this individual is suffering from what condition?

a) cryptorchidism
b) erectile dysfunction
c) premature ejaculation
d) hyperandrogenism

Answer 26

b) erectile dysfunction

Question 27

Which component of sexual function shows the greatest difference between men and women?

a) speed of arousal
b) involvement of the parasympathetic system
c) post-climax refractory period
d) frequency of orgasmic contractions of the perianal muscles
e) spinal organization of sexual reflexes

Answer 27

c) post-climax refractory period