Exam 1 - Erection and Ejaculation Flashcards
Define the two male sex acts.
erection - penis becomes rigid permitting entry into the vagina, a neuromuscular phenomenon resulting from changes in blood flow
ejaculation - discharge of semen from penis
Where is the smooth muscle in the penis and what happens to it during erection vs. flaccid state?
vascular compartments/sinusoidal spaces of the corpora cavernosa and corpus spongiosum
relaxes during erection and contracts during flaccid state
How does blood enter the penis (pathway) during smooth muscle relaxation/erection?
dorsal artery, circumflex artery, cavernous arteries, helicine arteries, sinusoidal spaces
How does blood exit the penis (pathway) during smooth muscle contraction/flaccid state?
sinusoidal spaces, circumflex veins, deep dorsal vein
What is the tunica albuginea? What purpose does it serve?
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
What are the skeletal muscles of the penis and what function do they serve?
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
Describe the flaccid and erect states of the penis as a variable-volume hydrostatic structure.
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
Fill out the nervous system flow chart from lecture 2
Done
Describe the afferent innervation (sensory receptors and nerves) of the male genital system
receptors: glans penis and penile shaft
nerves: dorsal nerve of the penis and pudendal nerve
Describe the somatic efferent innervation of the male genital system?
muscle: bulbospongiosus and ischiocavernosus muscles
motor nuerons: pudendal and perineal nerves
Describe the autonomic efferent innervation of the male genital system?
smooth muscle: corpora cavernosa and corpus spongiosum
sympathetic (adrenergic) and parasympathetic (cholinergic) NS: cavernous nerve
Describe the stimuli for the two types of erection?
psychogenic erection: thoughts, emotions, and sensory inputs like sight and smell trigger descending CNS pathways
reflexogenic erection: input from the penis mechanoreceptors
What kind of neuron activity stimulates erection?
decreased sympathetic, increase parasympathetic = relax smooth muscle
How does afferent/sensory information travel from the penis?
via the dorsal and pudendal nerves to higher centers (brain or spinal cord)
How does efferent/motor and autonomic information travel to the penile muscle?
cavernous nerve —> corpora cavernosa and corpus spongiosum smooth muscle
pudendal and perineal nerve —>
bulbospongiosus and ischiocavernosus skeletal mucle
What are the names of the 4 erection reflex loops and what do they generally control?
pudendo-cavernosal reflex loop: relax smooth
bulbocavernosus reflex loop: compress venous outflow
psychogenic pathway: relax smooth
ascending spinal pathway: integrate with higher centers
Describe the psychogenic pathway (type of info, nerves, location on the spinal cord, etc.)
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
Describe the pudendo-cavernosal reflex loop (type of info, nerves, location on the spinal cord, etc.)
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
Describe the bulbocavernosus reflex loop (type of info, nerves, location on the spinal cord, etc.)
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
What are the 4 phases of the sexual response cycle?
excitement phase, plateau phase, orgasmic phase, and resolution phase
Describe the excitement phase of sexual response
psychogenic or reflexogenic erection
Describe the plateau phase of sexual response
intensification of excitement phase
Describe the orgasmic phase of sexual response
ejaculation reflex (emission and expulsion)
rhythmic contractions of the penis are accompaniesd by increased respiration, heart rate, general muscle contraction, and heightened emotion
Describe the resolution phase of sexual response
return to pre-arousal state
latent period during which a second erection is not possible
What are the two reflexive, involuntary components of ejaculation? Describe them.
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
What is the difference in nervous pathways that are active during the emission and expulsion reflexes?
emission - near simultaneous sympathetic and parasympathetic reflexes
expulsion - somatic (motor) reflexes
What causes orgasm sensation?
near simultaneous activation of sympathetic and parasympathetic tension-release process
Is the brain involved in the ejaculation reflexes?
No, but it can modulate them
Describe the emission reflex (type of info, nerves, location on the spinal cord, etc.)
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
Describe the secretion reflex (type of info, nerves, location on the spinal cord, etc.)
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
Describe the expulsion reflex (type of info, nerves, location on the spinal cord, etc.)
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
What nerves send signals from spine to smooth muscle?
hypogastric and pelvic, then merge into the cavernous
What nerves send signals from spine to skeletal muscle?
pudendal which branches into the perineal
What nerves take signals from the penis to the spine?
dorsal which merges into the pudendal
