Lecture 38: COITUS, FERTILIZATION AND CONTRACEPTION Flashcards
What is coitus?
Sexual intercourse/copulation
When does coitus occur?
When the erect penis is introduced to the vagina (intromission)
What is insemination?
Semen released into upper part of vagins
What can happen because of insemination?
Sperm can travel to the appropriate site for fertilisation (ampulla of uterine tube)
What are the stages of the male sexual act?
Erection, ejaculation and resolution
What type of action is erection?
Parasympathetic
What also happens during erection?
Mucus from bulbourethral gland is secreted into the urethra
What are the parts of ejaculation?
Emission and expulsion which are both sympathetic
What are erectile tissues surrounded by?
Different layers of fascia
What are the corpora cavernous and corpus spongiosum surrounded by?
Separate tunica albuginea
What surrounds the tunica albuginea?
Deep fascia
What surrounds the deep fascia?
Superficial fascia
What is within the erectile tissue?
Smooth muscle fibres (trabecular) surrounding lacunae
What do the structure of the clitoris and penis share?
Developmental origins
Are the tissues of the clitoris erectile?
Yes
What is the path of blood supply to the penis?
Abdominal aorta > common iliac artery > internal iliac artery > internal pudenal artery
Where does the gonadal artery branch from?
High from the abdominal aorta as the testes develop quite high
What does the internal pudenal artery do?
Feeds the perineum and external genitalia, including penis
What do branches to the penis include?
artery to bulb, urethral artery, dorsal artery, deep (cavernosal) artery
What are the veins of the penis?
deep dorsal, superficial dorsal and subtunical
When does blood supply to the penis increase?
During erection, filling the lacunae
What is the penis richly innervated with?
Sensory and motor neurons
What does the nerve supply of the penis include?
Sensory fibres responsive to touch, pressure and temperature
What does the pudenal nerve supply?
Sensory and somatic motor innervation to perineum and external genitalia, including penis (dorsal nerve)
What is autonomic innervation to the penis dervied from?
Pelvic plexus (parasympathetic and sympathetic)
What does erection stimulate?
Production of nitric oxide (NO)- a vasodilator by deep arteries of the penis
What do deep arteries do during erection?
Dilate and fill lacunae in corpora cavernosa with blood
What control is ejaculation under?
Sympathetic and somatic
What sympathetic processes happen during ejaculation?
Stimulates contraction of smooth muscle, reproductive glands and accessory glands
What is the somatic actions during ejaculation?
Stimulates contraction of skeletal muscle around the bulb of the penis
Erection is a …
parasympathetic response to stimuli (visual, mental, tactile)
What is erectile dysfunction?
When erection can’t be maintained
What does the smooth muscle of the ductus deferens do during emission?
It contracts to move sperm into the ampulla (peristaltic contractions)
What do the smooth muscle of the ampulla, seminal vesicles and prostate gland do during emission?
Contract moving sperm and seminal fluid into the urethra
What does semen in the urethra activate (during expulsion)?
Somatic and sympathetic reflexes
What happens during expulsion?
Contractions of urethral smooth muscle, pelvic floor muscles contract and semen ejected
What happens in resolution?
Blood flow to penis is reduced and the penis becomes flaccid
What are the phases of the female sexual response similar to?
the reflex responses in the male
What happens to the clitoris, labia and vagina in response to autonomic stimulation during the female sexual response?
Engorgement
What is secreted through the vaginal wall in the female sexual response?
Lubricating fluid - secretion of mucus into vestibule (greater vestibule gland)
What happens to the vagina in the female sexual response?
Increased width and length of vagina
What happens to the uterus in the female sexual response?
It elevates upwards
What is there rhythmic contraction of in the female sexual response?
vagina, uterine and perineal (pelvic floor) muscles
What does sperm do when it reaches the ampulla?
Fuses wth the secondary oocyte
What does the oocyte do once the sperm has fused with it?
Complete meiosis 2
What is the fertilized oocyte/ovum known as?
A zygote
What does the zygote initiate?
Cleavage (about 7 days) and travels towards the uterus for implantation (now known as a blastocyst)
What is contraception?
any method used to prevent pregnancy which can regulate when and how many pregnancies occur
What are the methods of contraception?
Natural and artificial
What are the artificial methods of contraception?
Barrier methods, hormonal contraceptives, intrauterine devices and sterilisation
What do natural methods of contraception rely on?
Timing of coitus or behaviour during coitus
Natural methods of contraception have a …
high failure rate
What are some of the natural methods?
Rhythm method (periodic abstinence), withdrawal method (coitus interrputus), lactation infertility
What is involved in the rhythm method?
Tracking cycle and no sex during ovulation
What is involved in lactation infertility?
When breastfeeding don’t ovulate but it is difficult to know how long this will last
What are the barrier methods?
Caps, diaphragms and condoms
What are caps and diaphragms?
An imperfect barrier so should be used in conjunction with spermicidal foams/jellies/creams/sponges
How long after intercourse does a cap/diaphragm need to remain?
6 hours
Are caps and diaphragms commonly used?
Not anymore - preference for more effective and convenient methods
What are the benefit of condoms?
Cheap, readily available, easy to use and reduce risk STI (the only method which does this)
What are the steroidal contraceptives for females?
Combined oral contraceptive pills, progestin-only contraception
What do combined oral contraceptive pills contain?
Estrogen and progestin (provide negative feedback)
What do combined oral contraceptive pills do?
Suppress ovulation (affect feedback loops to hypothalamus and pituitary) and affect mucus produced by cervix making it more viscous (prevents sperm penetration)
What are some progestin-only contraception methods?
Progesterone-only pill and subdermal implant/injectable progestins
What does the progesterone-only pill have?
Low doses of progestin
What does the progesterone -only pill effect?
Cervical mucus
How long does the subnormal implant/injectable progestins last?
Long time (over years)
How do subnormal implants/injectable progestins work?
Primarily by disrupting follicular growth and ovulation
What are the types of IUD?
Copper and hormonal
What does the copper IUD do?
Causes low grade inflammation, reduces sperm transport, is toxic to the oocyte and zygote, impairs implantation
What does the hormonal IUD contain?
Progestins
What does the hormonal IUD affect?
Cervical mucus, reducing spermtransport, has local affects on endometrium and may prevent ovulation
What is the sterilisation method in females?
Tubal ligation
What happens in tubal ligation?
Cut and tie uterine tubes
What is the method of sterilisation in males?
Vasectomy
What is vasectomy?
Cut vas (ductus) deferens
What are caps and diaphragms?
An imperfect barrier so should be used in conjunction with spermicidal foams/jellies/creams/sponges
