Chapter Three: Men's bodies

Question 1

What are the three erectile structures of the penis?

Answer 1

• two corpora cavernosa that lie side by side and account for the bulk of the penis’s erectile capacity
• a single corpus spongiosum, which runs along the middle of the undersurface of the penis.

Question 2

What is the glans of the penis?

Answer 2

• the corpus spongiosum extends from the shaft into the glans, where it balloons out and fills the entire volume of the glans.

Question 3

What is the frenulum on the penis?

Answer 3

a loose strip of skin that runs between the glans and the shaft..

Question 4

how are the clitoris and penis anatomy similar in innervation?

Answer 4

• the penis and especially the glans is heavily innervated by dorsal nerves of the penis. (Tip)

Question 5

what is the physiology of erections?

Answer 5

that physical genital arousal is to a good degree a spinal reflex, like many others that exist within our body.

Question 6

Where does the sensory info from the glans travel to?

Answer 6

the sensory nerve fibers to the spinal cord.

Question 7

how do they synapse?

Answer 7

via interneurons, with output neurons, which travel back towards the genitals via the parasympathetic nerve fibers to the erectile tissue.
- it is an automatic reflex

Question 8

what is the state of the penis controlled by?

Answer 8

the sympathetic and parasympathetic signals that oppose each other.

Question 9

what is the flaccid state maintained by?

Answer 9

• the sympathetic nerve fibers that release the neurotransmitter norepinephrine.

Question 10

what is the erection state maintained by?

Answer 10

• the parasympathetic nerve fibers (reflex) release nitric oxide and acetylcholine making the sympathetic activity decrease.

Question 11

what are the key consequences of these different activations relating to the state of the arterioles and veins?

Answer 11

When PNS is winning, the open arterioles allow an influx of blood while the occluded veins keep it from leaving. The blood fills the space and loses it oxygen, turning purple.

Question 12

what causes the lubrication with erections?

Answer 12

the Vaso congestion associated with erection causes a pressure increase that induces higher transudation of fluid from Bartholin’s gland.

Question 13

What are also the pathways that are activated in the brain during arousal?

Answer 13

• the hypothalamus –> what goes on in the brain can get you aroused.

Question 14

What are the steps in helping the penis gain blood flow?

Answer 14

1. stimulation of the genital skin
2. activates sensory fibers in the pudendal nerve
3. signals pass to the dorsal horn of the sacral spinal cord
4. which activates interneurons.
5. then turns on motor neurons in a portion of the ventral horn known as Onuf’s nucleus
6. the motor neurons axis pass out through the pudendal nerve and innervate the bulbospongiosus muscle. Similar reflexes involve the ischiocavernosus muscles.
7. when these muscles contract, they pull on and squeeze the corpus spongiosum and corpora cavernosa, causing the penis to stick out from the body and become more engorged
8. the erect penis can be moved voluntarily by contraction of these same muscles.

Question 15

what is priapism?

Answer 15

an erection lasting more than a few hours.
- can cause tissue damage.
- can happen for both women and men.

Question 16

What is the treatment for priapism?

Answer 16

involves administration of norepinephrine or draining of the blood from the penis using a needle.

Question 17

What is spermatogenesis?

Answer 17

it occurs within the seminiferous tubules of the testis..

Question 18

What happens to the sperm over the course of a week?

Answer 18

sperm become more concentrated and mobile as they go through the epididymis.
- then the sperm travels up the vans deferens towards the ejaculatory duct, with additions (seminal plasma) from the prostate gland and seminal vesicle, which contributes most of the volume of the semen that will be ejaculated.

Question 19

What percentage of the semen ends up being sperm?

Answer 19

• 1%
• the rest is fructose for energy
• buffers to keep pH alkaline
• ascorbic acid for antioxidant protection

Question 20

What happens during the 2-3 second emission stage?

Answer 20

• all the components of semen merge and are loaded into the urethra.
• after that, ejaculation is mostly inevitable, and results from contraction of the urethra and assorted pelvic muscles.

Question 21

How often does contraction occur during ejaculations?

Answer 21

• occur once every 0.8 seconds or so.

Question 21

What is the refractory period?

Answer 21

• happens in males may relate to feedback mechanisms involving the above systems or from the release of hormones such as oxytocin..

Question 22

What is the bulbourethral gland?

Answer 22

produces a clear mucus (pre-cum) that is often emitted earlier during sexual arousal and precedes ejaculation of semen.

Question 23

What is associated with semen quality?

Answer 23

• varies inversely with scortal temperatures. ideally 4-7 degrees below body temperature.

Question 24

What are the cremaster muscles?

Answer 24

they contract to lift the testicles closer to the body.

Question 25

What are the dartos muscles?

Answer 25

they contract to make the scrotal skin more wrinkly, reducing heat loss.

Question 26

What is the prevalence of newborn circumcision, in Canada?

Answer 26

32%

Question 27

What are the pros of circumcision??

Answer 27

• reduced occurrence of UTIs
• lower rate of prostate cancer
• protection against cervical cancer
• less smegma

Question 28

What are the cons of circumcision?

Answer 28

• possible hemorrhage, infection, damage.
• death can occur, through sanitary conditions.
• can sensitivity be reduced?

Question 29

What did Bossio, Pukall and Steele’s study find about penile sensitivity in Neonatally circumcised and non-circumcised males?

Answer 29

• that there is no difference in sensivity between circumcised and non-circumcised men.

Question 30

Does circumcision alter adult socio-affective processing?

Answer 30

• yes, it can affect some areas of their life afterwards. such as anxiety, attachment avoidance and agreeableness.

Question 31

What are some penis disorders?

Answer 31

• Peyronie’s disease - fibrous plaque on corpus restricts symmetrical erection acts like a tether causing curvature. treatment is collagenase clostridium histolyticum, an enzyme that breaks down collagen plaques.
• Balanitis - involves inflammation of the glans area due to infections and buildup of environmental substances. more associated with poor hygiene.
• Phimosis - foreskin cannot contract over the glans.
  -paraphimosis - infections and physical trauma from phimosis.

Question 32

what is the consensus on size mattering to men?

Answer 32

• penis length does matter to most men in Veale, Miles, Bramley, Muir and Hodsoll’s study

Question 33

What was the overall attitudes towards their partners penis size?

Answer 33

• women were 85% satisfied with their partners penis than were the males themselves 55%.

Question 34

What did Loehle et al (2017) study find?

Answer 34

that genital self-image significantly associated only with other issues related to self-perception.

Question 35

What did Stephen Cranney’s study on internet porn use and sexual body image in Dutch sample find?

Answer 35

• found evidence supporting an effect of porn on genital dissatisfaction. - some mixed results in other studies however.