Exam 1 - Erection and Ejaculation

Question 1

Define the two male sex acts.

Answer 1

erection - penis becomes rigid permitting entry into the vagina, a neuromuscular phenomenon resulting from changes in blood flow

ejaculation - discharge of semen from penis

Question 2

Where is the smooth muscle in the penis and what happens to it during erection vs. flaccid state?

Answer 2

vascular compartments/sinusoidal spaces of the corpora cavernosa and corpus spongiosum

relaxes during erection and contracts during flaccid state

Question 3

How does blood enter the penis (pathway) during smooth muscle relaxation/erection?

Answer 3

dorsal artery, circumflex artery, cavernous arteries, helicine arteries, sinusoidal spaces

Question 4

How does blood exit the penis (pathway) during smooth muscle contraction/flaccid state?

Answer 4

sinusoidal spaces, circumflex veins, deep dorsal vein

Question 5

What is the tunica albuginea? What purpose does it serve?

Answer 5

a tough, fibroelastic layer that surrounds the corpora cavernosa and corpus spongiosum

since the penis is a variable-volume hydrostatic structure, it keep the walls in tension

Question 6

What are the skeletal muscles of the penis and what function do they serve?

Answer 6

ischiocavernosus muscle (down each side) and bulbospongiosus muscle (around the base)

contract during erection- compress venous outflow which forces blood to stay in the penis

Question 7

Describe the flaccid and erect states of the penis as a variable-volume hydrostatic structure.

Answer 7

flaccid -
arteries suppling the vascular compartments are contricted (little blood in)

erect -
arteries dilate, vascular compartments expand (more blood in)
veins are compressed (less blood out)
blood pressure in the penis increases and it becomes rigid

Question 8

Fill out the nervous system flow chart from lecture 2

Answer 8

Done

Question 9

Describe the afferent innervation (sensory receptors and nerves) of the male genital system

Answer 9

receptors: glans penis and penile shaft

nerves: dorsal nerve of the penis and pudendal nerve

Question 10

Describe the somatic efferent innervation of the male genital system?

Answer 10

muscle: bulbospongiosus and ischiocavernosus muscles

motor nuerons: pudendal and perineal nerves

Question 11

Describe the autonomic efferent innervation of the male genital system?

Answer 11

smooth muscle: corpora cavernosa and corpus spongiosum

sympathetic (adrenergic) and parasympathetic (cholinergic) NS: cavernous nerve

Question 12

Describe the stimuli for the two types of erection?

Answer 12

psychogenic erection: thoughts, emotions, and sensory inputs like sight and smell trigger descending CNS pathways

reflexogenic erection: input from the penis mechanoreceptors

Question 13

What kind of neuron activity stimulates erection?

Answer 13

decreased sympathetic, increase parasympathetic = relax smooth muscle

Question 14

How does afferent/sensory information travel from the penis?

Answer 14

via the dorsal and pudendal nerves to higher centers (brain or spinal cord)

Question 15

How does efferent/motor and autonomic information travel to the penile muscle?

Answer 15

cavernous nerve —> corpora cavernosa and corpus spongiosum smooth muscle

pudendal and perineal nerve —>
bulbospongiosus and ischiocavernosus skeletal mucle

Question 16

What are the names of the 4 erection reflex loops and what do they generally control?

Answer 16

pudendo-cavernosal reflex loop: relax smooth

bulbocavernosus reflex loop: compress venous outflow

psychogenic pathway: relax smooth

ascending spinal pathway: integrate with higher centers

Question 17

Describe the psychogenic pathway (type of info, nerves, location on the spinal cord, etc.)

Answer 17

efferent info carried from brain to smooth muscles

the hypogastric nerve deviates around T10 and the pelvic nerve deviates around S2-S4

relax smooth muscle

Question 18

Describe the pudendo-cavernosal reflex loop (type of info, nerves, location on the spinal cord, etc.)

Answer 18

Afferent info from penile sensory receptors carried to the sacral spinal cord (S2-S4) via the dorsal nerve of the penis and pudendal nerve

efferent info from spinal cord comes back to smooth muscle via pelvic (S2-S4), hypogastric and cavernous (T10) nerves

relaxes smooth muscle

Question 19

Describe the bulbocavernosus reflex loop (type of info, nerves, location on the spinal cord, etc.)

Answer 19

Afferent info from penile sensory receptors carried to the sacral spinal cord (S2-S4) via the dorsal nerve of the penis and pudendal nerve

efferent info from spinal cord comes back to skeletal muscle via pudendal and perineal nerves (S2-S4)

contraction of skeletal muscle compresses venous outflow

Question 20

What are the 4 phases of the sexual response cycle?

Answer 20

excitement phase, plateau phase, orgasmic phase, and resolution phase

Question 21

Describe the excitement phase of sexual response

Answer 21

psychogenic or reflexogenic erection

Question 22

Describe the plateau phase of sexual response

Answer 22

intensification of excitement phase

Question 23

Describe the orgasmic phase of sexual response

Answer 23

ejaculation reflex (emission and expulsion)
rhythmic contractions of the penis are accompaniesd by increased respiration, heart rate, general muscle contraction, and heightened emotion

Question 24

Describe the resolution phase of sexual response

Answer 24

return to pre-arousal state
latent period during which a second erection is not possible

Question 25

What are the two reflexive, involuntary components of ejaculation? Describe them.

Answer 25

emission -
in response to sensory penile afferents, smooth muscle contracts in the epididymis, vas deferens, ejaculatory ducts, prostate, and seminal vesicles to deposit sperm and secretions into the urethra
Contraction of the urinary bladder sphincter keeps semen from entering the bladder or urine from entering the ejaculate

expulsion -
in response to urethral afferents (filling of the urethra), rhythmic contractions of skeletal muscle at the base of the penis expels semen

Question 26

What is the difference in nervous pathways that are active during the emission and expulsion reflexes?

Answer 26

emission - near simultaneous sympathetic and parasympathetic reflexes

expulsion - somatic (motor) reflexes

Question 27

What causes orgasm sensation?

Answer 27

near simultaneous activation of sympathetic and parasympathetic tension-release process

Question 28

Is the brain involved in the ejaculation reflexes?

Answer 28

No, but it can modulate them

Question 29

Describe the emission reflex (type of info, nerves, location on the spinal cord, etc.)

Answer 29

sensory/afferent info from penis travels to S1-S3 via pudendal nerve

sympathetic info from T12-L1 trigger contraction of accessory glands to empty into the urethra
simultaneously…
parasympathetic info from S1-S3 trigger relaxation of the accessory glands to empty into the urethra

Question 30

Describe the secretion reflex (type of info, nerves, location on the spinal cord, etc.)

Answer 30

sensory/afferent info from penis travels to S1-S3 via pudendal nerve

parasympathetic info from S1-S3 trigger contraction of accessory glands to deposit secretions into the urethra

Question 31

Describe the expulsion reflex (type of info, nerves, location on the spinal cord, etc.)

Answer 31

sensory/afferent info from penis travels to S1-S3 via pudendal nerve

motor info from S1-S3 causes contraction of the bulbospongiosis muscle (skeletal) which results in ejaculation

Question 32

What nerves send signals from spine to smooth muscle?

Answer 32

hypogastric and pelvic, then merge into the cavernous

Question 33

What nerves send signals from spine to skeletal muscle?

Answer 33

pudendal which branches into the perineal

Question 34

What nerves take signals from the penis to the spine?

Answer 34

dorsal which merges into the pudendal