Physiology 4 (pt 3)

• Acidic environment of the vagina
• Thick curtain of cervical mucous (thinned prior and during ovulation due to high levels of estrogen)
• Subjected to uterine contractions that disperse the sperm and make available to phagocytes

• Sperm membranes must be made fragile so that enzymes can be released from the heads of the sperm
• Usually takes about 6-8 hours

• Produced in the seminiferous tubules of the testes 
• Sertoli cells help nourish sperm and regulate the process of sperm and regulate the process of sperm production (spermatogenesis)

Epididymis

• Is its nucleus
• Covered by the acrosome (Contains enzymes necessary to penetrate the egg)

Contains mitochondria for energy production (swimming)

Flagellum which allows sperm to swim

• Parasympathetic response
• When a man is sexually aroused, reflex is triggered which promotes a local release of nitric oxide (NO)
• This relaxes vascular smooth muscle and causes the arterioles in the penis to dilate. The spaces of the erectile tissues in the penis fill with blood and cause an erection

Parasympathetic system stimulates this during erection to produce a clear mucus to clear the urethra of urine and lubricate the glans penis

• Sympathetic response
• Reproductive ducts and accessory glands contract, bladder sphincter muscles constrict, preventing urine outflow or semen into bladder

During ejaculation, undergoes a rapid series of contraction and semen is ejaculated from the penis

• Vas deferens: Carries sperm to the urethra
• Ejaculation

• Flagellum
• Contractions in female reproductive system during orgasm to help disperse the sperm through out the female tract
• Prostaglandins in the semen induce contractions

• High pH: mucus is alkaline which neutralizes the female secretions
• Prostaglandins that alter cervical mucus: make the cervical mucus thinner which allows the sperm to enter female tract easier

• Comes from hypothalamus
• Released in bursts every 90 mins
• This hormone is Gonadotropin Releasing Hormone (GnRH) and it causes the release of FSH and LH from the anterior pituitary gland

In female, it helps drive the process of menstruation and development of fetus

• Stimulates the interstitial cells of the testes to produce testosterone 
• In anterior pituitary hormones

In females: release egg to ovary

• Stimulates the seminiferous tubules of the testes to produce sperm
• In anterior pituitary hormones

In females, stimulates the eggs to develop and the follicles on the ovary to mature and produces estrogen

• Stimulates spermatogenesis and also the development of secondary sex characteristics of the male
• Involved in libido
• Exert a negative feedback effect on GnRH and LH to inhibit production of those hormones

• Contains many follicles each containing an immature egg (oocyte)
• At puberty a female has 300,000-400,000 follicles approx halfway through meiotic divisions

• One follicle matures each month from puberty until menopause
• Ovulation is monthly release of an oocyte from the ovary when a follicle ruptures

• Forming the eggs
• Begins before birth (5 mo fetal) and halts until puberty; completion after fertilization
• Follicle matures through a timed hormone release, oocyte is ejected from the ovary during ovulation
• To create an egg, the meiotic divisions form one complete ova, with all the cytoplasm, DNA and organelles

Cells around the ovum (in the ovary) and they develop along with the ovum

• When ovulation occurs, these cells remain on the ovary and become this
• Source of progesterone and estrogen

• Egg and surrounding cells are released from the ovary (ruptures the outer cortex)
• Zona pellucida (thick membrane around egg) and corona radiata (layer of cells around zona pellucida) are ovulated with the egg
• Egg and surrounding cells will enter the fallopian tubes

• Fallopian tubes
• Site of fertilization 
• Lining of the fallopian tubes contain cilia which help move the egg along inside the fallopian tubes

• Involves erection of the clitoris
• Sometimes, an orgasm (feelings of intense pleasure associated with intercourse) will occur

Orgasm doesn't affect fertility

Stimulate growth of pubic and axillary hair and also stimulates the sex drive

Stimulates growth of the egg and follicles on the ovary and the development of the secondary sex characteristics of the female

• Released by corpus leuteum
• Main job is to ready the uterus for implantation of uterus and maintain embryo until formation of amniotic sac

Ranges from 24-35 days (28 days are ideal)

• Menstrual phase (menstruation)
• Proliferative phase (preovulatory)
• Secretory phase (postovulatory)

• Days 1-5 of cycle
• Estrogen and progesterone levels are at their lowest
• Inner lining of endometrium is shed (menses)
• At the end of this phase, the low levels of estrogen turns on their anterior pituitary's release of FSH 
• ~20 immature follicles begin to enlarge

• Days 6-13 of cycle
• Controlled by GnRH of hypothalamus
• FSH stimulates several primitive follicles and their eggs to begin maturing
• Follicles secrete estrogen, peak levels on day 14
• Rising levels of estrogen stimulate the endometrium and lining of the vagina to proliferate or to thicken with tissue
• At end of this stage, high levels of estrogen turn off FSH

The combination of high estrogen and low progesterone turns on LH

• Day 14 of cycle
• Increasing level of LH stimulates one of the maturing follicles allows the release of the ovum from that follicle into the pelvic cavity
• Big rise in oral temperature in this

• Days 15-28 of cycle
• LH stimulates the remnants of the ruptured follicle within the ovarian cortex to change into the corpus luteum
• Produces large amounts of progesterone

• Stimulates the endometrial glands of the uterus to begin secreting
• Inhibits myometrial contractions
• Increases the vascularity of the endometrial lining

• Fertilized egg produces HCGF around 6-8 days after fertilization
• HCG stimulates mother's corpus luteum to continue producing progesterone even though LH has dropped

• Very narrow window
• Eggs viable for 1 day 
• Sperm viable for 2-3 days

It takes between 1 to 3 minutes for sperm to reach the eggs after ejaculation

• Hormone produced by the chorion of the embryo as early as 8-12 days after fertilization
• Chorion develops into the placenta which eventually takes over the job of the corpus luteum in hormone secretion

• The egg is surrounded by an outer matrix called the zona of pellucida
• Outside the matrix it has a few layers of follicular cells collectively called corona radiata

• There is no production of HCG, the high levels of progesterone and estrogen turn off LH at the end of this stage
• Drop in LH shuts down the corpus luteum
• Drop in progesterone decreases the blood supply to the endometrium resulting in necroses and shedding of endometrial lining (back to menses)

• Ovum: 12-24 hours
• Sperm: 48-72 hours

Acrosome releases its enzymes and those enzymes digest through the corona radiata and zona pellucida around the egg to allow sperm to enter the egg

• Cortical granules just inside the egg fuse together to put a layer of water like a "moat"
• Prevents polyspermy

Sperm and egg nuclei join to form the zygote

• Begins with gamete formation
• Zygote forms when eggs and egg fuse
• Cleavage: mitotic cell divisions that follow zygote formation that convert the zygote into ball of cells

• For 3-4 days after fertilization, zygote travels down the fallopian tube
• Undergoes its first cleavage
• By the time the cluster of dividing cells reaches the uterus, it is a solid ball of cells called the morula

The ball is transformed into this which consists of a surface layer of cells trophoblast (becomes placenta) and a clump of cells to one side called the inner cell mass

Embryo develops

• Occurs within a week after fertilization
• Trophoblast adheres to the lining of the uterus
• Trophoblast cells secrete enzymes to digest the lining (foothold)
• Implatation is complete 14 days after ofulation
• The fertilized egg secretes HCG which prevents menstruation

• During first trimester
• Organs form
• Sensitivity to disruption: baby can be damaged by teratogens (environment agents that can cause birth defects)
• Cell differentiation
• Morphogenesis: produces shape and structure of body regions

• Embryo's bloodstream remains distinct from mother's 
• Oxygen and nutrients diffuse out of mother's blood vessels, across blood filled spaces in endometrium, then into embryo's umbilical blood vessels i.e alcohol and caffiene

• 2nd and 3rd trimesters
• Organ specialization and growth occurs at this time
• Right before birth, surfactant is produced in lungs

• Hair develops
• Head growth slows
• Distinguished males and females
• Heartbeat with stethoscope

Fetal movement felt by mother

• Fetus rotates so head is pointed towards cervix
• Fetus weighs ~7.5 lbs and 20.5 inches

• Vasectomy (males)
• Tubal ligations (females)

Condom, diaphragm, cervical cap

• Oral contraceptive pill
• Depo provera

Contain synthetic progesterone which acts like the body's progesterone to cause negative feedbach inhibition of FSH and LH release which prevents ovulation and implantation

• IUD
• Birth control pills

Set up a hostile environment within the uterus which will not allow the baby to implant

• Rhythm method: women keeps track of when she ovulates and avoids intercourse around that time
• Monitoring cervical mucus: mucus is thin and slippery when ovulating

• Preven: morning after pill
• RU-486: causes loss of implanted embryo (more effective)

• antigen on the Y chromosome which caues the indifferent gonad to differentiate into a testis
• If not present, indifferent gonad differentiates into an ovary

• During childhood, the hypothalamus and pituitary gland are very sensitive to low levels of estrogen and testosterone circulating in the blood so they don't release hormones
• But during adolescence, they are less sensitive so are not inhibited by low levels so you get increase in GnRH, FSH, LH, Estrogen, Testosterone

Caused by the increased testosterone in the male and increased estrogen in the female

Caused by the action of FSH and LH

Senescence: process of aging

• After 40 the body changes include:
• Bone and muscle mass decline
• Increased skin wrinkling
• More fat deposition
• Immune system declines

• Ovarian changes: less responsive to FSH and LH and stop functioning
• Altered hormone production: decreased estrogen
• Associated pathologies: osteoporosis, heart disease, stroke, high cholesterol, cancer, all due to low estrogen levels