22. Chapter 26- Part 2

Question 1

What are the 4 phases of ovulation?

Answer 1

1. Early to mid-follicular stage- low levels of estrogen cause negative feedback to GnRH, FSH, LH (estrogen promotes more estrogen secretion
2. Late follicular phase and ovulation- rising levels of estrogen and increasing progesterone cause LH surge
3. Early to mid-luteal phase- combined estrogen and progesterone shut off FSH and LH
4. Late luteal phase- estrogen and progesterone fall when corpus luteum dies (gonadotrophins start follicular development for a new cycle)
   Slides 3-6 Mar 25

Question 2

Which hormones produce which female secondary sex characteristics (physical characteristics)?

Answer 2

Estrogen- breast development, pattern of fat distribution to hips and upper thighs
Androgens- pubic and armpit hair, libido (sex drive)

These are produced by adrenal cortex
Slide 7 Mar 25

Question 3

What is procreation?

Answer 3

Reproduction marked by species-specific behaviours designed to ensure that egg and sperm meet
In terrestrial vertebrates, internal fertilization requires interactive behaviours and specialized adaptations of the genitalia (females must have a receptacle for sperm, males must possess an organ to deposit sperm into receptacle)

Question 4

What are the 4 components of the human sexual response?

Answer 4

1. Excitement- erotic stimuli prepare for copulation (erection in both sexes is a state of vasocongestion, arterial blood blood into spongy erectile tissue exceeds venous outflow)
2. Plateau- changes that started during excitement intensify
3. Orgasm- climax in both sexes is a series of muscle contractions accompanied by intense pleasurable sensations and increased blood pressure, heart rate, and respiration rates
4. Resolution- parameters return to normal
   Slides 9-10 Mar 25

Question 5

What is the erection reflex?

Answer 5

A key element to successful copulation is the ability of the male to achieve and sustain an erection
ACh released from parasympathetic nerves binds muscarinic ACh receptors on endothelial cells (results in production of nitric oxide in endothelial cells, this enters smooth muscle cells and causes relaxation of vascular smooth muscle)
Slides 11-12 Mar 25

Question 6

What is emission and ejaculation?

Answer 6

Emission (sympathetic)- movement of sperm out of the vas deferens and into the urethra, where it is joined by secretions from the accessory glands to make semen
Ejaculation (somatic)- expulsion of semen by a series of rapid muscular contractions accompanied by sensations of pleasure (erection and ejaculation can occur in absence of mechanical stimulation, non sexual erection occurs in REM sleep)

Question 7

What is erectile disfunction?

Answer 7

Erectile disfunction (impotence) is the inability to achieve or sustain an erection, disrupts the sex act for both men and women
Causes:
Diabetes: damage to nerves and vascular
Cardiovascular disease and atherosclerosis: ED can be an early warning of CVD
Drugs, alcohol, etc

Question 8

What is female sexual dysfunction?

(Ways to fix it0

Answer 8

Most commonly low sexual desire
Flibanserin (addyi) helps restore prefrontal cortex control over the brains motivation/reward pathways that enable sexual desire
Androgen therapy phase 3 trial bremelanotide which is a synthetic hormone that acts in the hypothalamus to target the melanocortin receptor (believed to be involved in upregulating a woman’s sexual response to appropriate cues)

Question 9

What are the 3 categories contraceptive falls under?

Answer 9

1. Abstinence- total avoidance of sexual intercourse
2. Sterilization- tubal ligation or vasectomy
3. Interventional methods: barrier methods, implantation, prevention, and hormonal treatments
   Slide 17-19 Mar 25

Question 10

What is implantation prevention?

Answer 10

Some contraceptive methods do not prevent fertilization but rather prevent implantation of fertilized egg in the uterine wall
Intrauterine devices (IUD) and chemicals that change properties of the endometrium

Question 11

What a re the male contraceptives in development?

Answer 11

RISUG/VasalGel- reversible inhibition of sperm under guidance, injection of polymer gel into vas deferens

Also male hormone contraception- combination of progestin and androgen therapy
Slides 6-8 Mar 27

Question 12

What is infertility in males and females?

Answer 12

Males- low sperm count, abnormal sperm, abnormal motility
Infections: STI’s, prostatitis, mumps
Females- damaged Fallopian tubes, polycystic ovaries, endometriosis, uterine/cervical disorders
Slides 9-10 Mar 27

Question 13

What is assisted reproductive technology?

Answer 13

In vitro fertilization slide 11 Mar 27
Artificial insemination- intracervical insemination (ICI), intratubual insemination (ITI), and intrauterine insemination (IUI)
Slide 12 Mar 27

Question 14

What is capacitation of sperm for fertilization?

Answer 14

Fertilization requires capacitation
Sperm sheds surface molecules (proteins and carbohydrates) allowing them to rapidly swim and penetrate an egg, believed to depend on substances produced in uterus
Fertilization of egg by sperm occurs by chance, possibly aided by chemical attractants produced by the egg
Slide 13 Mar 27

Question 15

How does fertilization occur?

Answer 15

Commonly occurs in distal portion of Fallopian tube
Of the millions of sperm deposited, about 100 reach this point
Sperm must penetrate loosely connected granulosa cells and the zona pellucida layer
Slide 14-16 Mar 27

Question 16

Where does the developing embryo implant?

Answer 16

In the endometrium

Slide 17 Mar 27

Question 17

What is a blastocyst?

Answer 17

Approx 100 cells
Outer cell layer (trophoblast) surrounds an inner cell mass
Implants approx 7 days after ovulation
Upon contact with endometrium trophoblasts proliferate and secrete proteolytic enzymes allowing blastocyst to penetrate wall
Outer layer of blastocyst forms an extra embryonic membrane (chorion) enclosing the embryo and forming placenta
Slides 18-19 Mar 27

Question 18

What is amnion and allantois?

Answer 18

Amnion- secretes amniotic fluid
Allantois- becomes part of the umbilical cord

These two are extraembryonic membranes

Question 19

What is the placenta?

Answer 19

Outer layer of cells, chorion, that will become placenta begin to form the chorionic villi that penetrate vascularized endometrium
Secrete enzymes that break down walls of maternal blood vessels
Nutrients gases and wastes exchange across membranes of villi mainly by diffusion
Slide 20 Mar 27

Question 20

What is human chorionic gonadotropin?

Answer 20

Chorionic villi of developing placenta secrete human chorionic gonadotropin (hCG) which binds LH receptors of corpus luteum, continues hormone secretion, keeping endometrium intact
hCG stimulates testosterone production in developing testes in male fetuses
hCG is hormone detected by pregnancy tests
Slides 13-14 Mar 29

Question 21

What are the 3 hormones the placenta secretes?

Answer 21

Progesterone and estrogen- negative feedback to HPG axis prevents follicle development, estrogen develops milk secreting ducts in breasts, progesterone maintains endometrium, suppress contractions
Human placental lactogen (hPL) aka human chorionic somatomammotrophin (hCS)- alters mothers glucose and fatty acid metabolism to support fetal growth

Question 22

What is parturition?

Answer 22

The birth process
Occurs between 38th-40th week of gestation
Begins with labor, rhythmic contractions of the uterus
Some animals drops estrogen and progesterone to signal contractions, not the case in humans
Days prior to labor, the cervix softens and ligaments holding pelvic bones together loosens under enzymatic control
Slides 16-18 Mar 29

Question 23

What secrets milk during lactation?

Answer 23

Mammary glands

Slide 19 Mar 29

Question 24

What is lactation?

Answer 24

During puberty estrogen stimulates the growth and branching of milk ducts and deposition of fat
Glands further develop at pregnancy due to estrogen, growth hormone and cortisol
Progesterone converts epithelium into a secretory structure
Progesterone and estrogen inhibit milk production
Slides 19-21 Mar 29

Question 25

What controls milk production?

What causes milk ejection?

Answer 25

Prolactin
Secreted from anterior Pitcairn
Prolactin is under control of prolactin inhibitory hormone (PIH) (dopamine) which drops later in pregnancy
Oxytocin causes milk ejection, contraction of smooth muscle in breast (myoepithelial) and uterus
Slide 21-22 Mar 29

Question 26

What happens during puberty in males and females?

Answer 26

Males- subtle, growth, and maturation of genitalia, pubic and facial hair, lowering of voice, change in body shape and height (9-14 years old)
Maturation of hypothalamic-pituitary pathway increases pulsatile secretion
Females- budding breasts and first menstrual period (menarche) (8-13 years old)

Question 27

What is menopause and andropause?

Answer 27

Menopause- the cessation of the female reproductive cycles
Approx 40 years after first menstruated Cycle
Ovaries no longer respond to gonadotropins
Andropause- testosterone production decreases with age, 50% of men over 50 have symptoms of andropause
Decrease in leydig cells