coitus and contraception

Question 1

comparative anatomy of clitoris and penis

Answer 1

structures of clitoris and penis are homologous. Tissues of clitoris are erectile as in the penis

Question 2

layers of fascia of penis

Answer 2

dartos fascia (outer), superficial fascia, deep fascia

Question 3

how is an erection maintained

Answer 3

Deep arteries vasodilate so more blood flow to corpora cavernosa

Filling of lacunae compresses veins which prevents blood leaving

Question 4

blood supply to penis

Answer 4

abdominal aorta –> common iliac artery –> internal iliac artery –> internal pudendal artery (supplies perineum and external genitalia)

Question 5

arteries in penis

Answer 5

artery to bulb

urethral artery

dorsal artery

deep (cavernosal) artery

Question 6

why does corpus spongiosum not get erect

Answer 6

tunica surrounding is thinner - important so it does not compress urethra

Question 7

nerve supply to penis

Answer 7

richly innervated by sensory and motor nerves

responsive to touch, pressure and temp

pudental nerve supplies sensory and somatic motor innervation to perineum and external genitalia (dorsal nerve of penis)

Sympathetic and parasympathetic pathways converge on pelvic plexus

Question 8

how is erection controlled

Answer 8

Parasympathetic NS in response to visual, mental or physical stimulus stimulates production of nitric oxide (NO, vasodilator) by deep arteries of penis.

Deep arteries dilate and fill lacunae in corpora cavernosum

Question 9

how is emission controlled

Answer 9

Sympathetic NS stimulates contraction of smooth muscle of ductus deferens to move sperm into ampulla (peristaltic contractions).

Smooth muscle of ampulla, seminal vesicles and prostrate gland contract moving sperm and seminal fluid into urethra

Question 10

how is expulsion controlled

Answer 10

Semen in urethra activates somatic and sympathetic reflexes

Contractions of urethral smooth muscles.

internal urethral sphincter contracts

Pelvic floor muscles (bulbocavernous) contract

Semen ejected

Question 11

what happens in resolution (after ejaculation)

Answer 11

efferent sympathetic signals cause:

• internal pudendal artery constricts which reduces blood flow to penis
• trabecular muscles contract to squeeze blood from erectile tissues
• penis becomes flaccid

Question 12

stages of female sexual response

Answer 12

1. Engorgement of corpora of clitoris, bulbs of vestibule, labia and vagina in response to autonomic stimulation
2. Lubricating fluid secreted through vaginal wall; secretion of mucus into vestibule (greater vestibular glands)
3. Increased width and length of vagina in response to tactile stimulation. Uterus elevates upwards.
4. Rhythmic contraction of vaginal, uterine and perineal (pelvic floor) muscles in response to stimuli from pudendal nerve

Question 13

natural methods of contraception

Answer 13

Rhythm method (periodic abstinence)

Withdrawal method (coitus interruptus)

lactational infertility - infertile whilr lactating

• high failure rate
• rely on timing of coitus or behaviour during

Question 14

diaphragm

Question 15

condom

Answer 15

cheap

easy to use

reduce risk of STI

Question 16

combined oral contraceptive (the pill)

Answer 16

contain estrogen and progestin

suppress ovulation

thicken mucus from cervix

Question 17

progesterone-only pill

Answer 17

effects cervical mucus

Question 18

subdermal progestin implant

Answer 18

long acting

disrupt follicle growth and ovulation

Question 19

copper IUD

Answer 19

low grade inflammation

reduces sperm transport

toxic to oocyte and zygote

impairs implantation

Question 20

hormonal IUD

Answer 20

contains progestins

affects cervical mucus

affects endometrium

may prevent ovulation

Question 21

what is cutting uterine tubes called

Answer 21

tubal ligation

Question 22

what is a vasectomy

Answer 22

cutting ductus deferens

Question 23

what is removing entire uterus called

Answer 23

hysterectomy