Human Reproductive System Notes

Human Reproductive System

Male Reproductive Physiology
Hypothalamus --> GnRH --> Anterior Pituitary --> FSH --> Seminiferous tubules
Hypothalamus --> GnRH --> Anterior Pituitary --> LH --> Leydig Cells

Male reproductive system is regulated by negative feedback.

Testosterone—hormone that is secreted in the testes influencing the production of sperm and producing secondary sex hormones
Follicle Stimulating Hormone (FSH)

FSH goes to seminerfous tubules and cause spermatocyte to develop into the sperm. In the seminerfous are also sertoli cell which are designed to nourish, mature and develop the sperm.

Leutenizing hormone

LH goes to other cells in the testes called Leydig cells causing production of testosterone.

Seminiferous Tubule—where the sperm is produced
Sertoli Cells—help nourish, develop the cell
Leydig (interstitial) cells—produces testerone

These are the cell that are targeted by the LH
Cause the production of Testosterone

Epididymus—Stores sperm. This is where the sperm becomes mature and motile.

Gubernacular—pulls the spermatic chord down. The spermatic chord has testicular artery and vein and the vas deferen.

The scrotum is attached to the pereteum cavity.

Sign of puberty—growth of testes is the first sign because FSH and LH are going to the testes. After two years of puberty, secondary sex characteristics occur such as growth spurt, skeletal muscle mass increase and penis growth. Pubic and axillary hair also grow and the enlargement of larynx occurs (deepens voice).

Testosterone feeds back onto the hypothalamus and tells it that we produced enough testosterone.

This is the example of the male pituitary reproductive system being regulated by negative feedback.

(male reproductive system)

Factors affecting sperm production

Temperature

Increased temperature decreases sperm production
Wearing tight underwear cause the sperm to be close to the body, getting heat from the body, decreasing sperm count. The cremaster muscle of the testes regulates this process. If the environment is too cold, then the muscle takes the testes close to the body.
Countercurrent heat exchange occurs at the capillary bed of the testes.

Varicocoele: when the countercurrent heat exchange doesn’t work well

Sexually Transmitted Disease

Scar tissue develop in the vas deferens preventing sperm to be released

Drug and Alcohol
Motility

The sperm has to be motile. Therefore, doctors check the motility of the sperm

Psychological Behavior

Male Sexual response (male reproductive system)

Parasympathetic nervous system controls erection of the penis

Nitric oxide signal the parasympathetic ns, causing the blood to flow to the penis

Emission

Sympathetic nervous sytem—causes contractions of vas deferens, seminal vesicle and prostate.

In the ejaculate: 1-2% is sperm. Very low amount
Seminal vesicle—75% of ejaculate. Produces semen which has sugars nourishing the sperm. The pH is basic because vagina is acidic.
Prostate—has antibiotic that goes with the sperm

Ejaculation reflex: Somatic spinal reflex involving skeletal muscle. This is when the semen enters the urethra.

Men release endorphins during orgasm.

Female reproductive system

During puberty:

Hypothalamus releases GnRH during puberty. FSH and LH released by anterior pituitary.
First sign of puberty for women: Breast development
Menarche: First menstrual cycle (about 2-3 years after puberty started)

Female Menstrual Cycle

Most fertility drugs are mimics of FSH, more eggs get produced.
Contraceptives

Orals:Contains estrogen and progesterone, which causes negative feedback. This means that LH and FSH are not released. If LH is not released then ovulation can’t occur. Progesterone maintains the uterine lining. But once progesterone is being stopped, sugar is giving then menstruation occurs.
Implant: (patch or subdural implants): Smaller amounts of estrogen and progesterone go directly into the bloodstream instead of directly in the liver. The liver filters the substances in the orals.
Progesterone Analog—purely progesterone. Prevents LH secretion for about three months. This is because estrogen therapy has side-effects
RU-486—morning after pill. Binds to progesterone receptor onto the endometrium. Progesterone can’t bind, which causes slough off of uterine lining. Egg is prevented from implantation.

Miscarraiges

60% of the fertilization is miscarriages.

This is because the female is not making enough estrogen and progesterone.
Another reason is that the egg has bad implantation onto the uterine lining.
Another reason is the bad development of placenta (bad maternal blood).
Maternal blood supply is inaccurate. In these cases, most women don’t know that they are pregnant.

(female reproductive system)

Fertilization

Most fertilization occurs in the fallopian tube. This is why sperm must have motility.

Cleavage occurs once fertilization occurs. The zygote divides rapidly. Cleavage—really fast mitosis. When the zygote divides, the it divides so fast that the size of the egg stays the same. That’s why the female egg is 50-100x bigger than the sperm
The cell becomes a Morula—Solid Ball of cells
Now in the uterus, a Blastula (hollow cells) develops and implants onto the uterus.
After implantation, gastrulation occurs. This is when the developing embryo forms the primitive gut (the tube forms).

Endoderm (digestive lining and organs, inner layer of the gastrula) Ectoderm (forms nervous system, integument), Mesoderm (connective tissue, cardiovascular system, urinary system)

Neuralation

Organs, brain starts to form

Pregnancy Test

Corpus luteum makes progesterone, producing the uterine lining for the fertilized egg to attach onto.
Blastula produce HCG. The developing embryo makes the HCG. HCG gets filtered at the glomerulus and its not reabsorbed.

False negative can occur, because HCG hasn’t developed
Fasle positive (saying you are pregnant, but actually you are not)—very rare

HCG can mask previous steroid use in males.

Placenta—made after a couple months of fertilization.

Placenta makes the estrogen and progesterone. If placenta gets bigger, the hormone levels increase.

Progesterone levels have to stay high in pregnancy to keep the lining intact so the fetus won’t slough off.
Increase estrogen makes women very nausea (morning sickness). However, the morning sickness goes away.

After pregnancy, estrogen and progesterone causes a big drop off. Women can become very moody and depressed.

Placenta has a huge network of capillary connecting the women and the fetus. Veins go to the baby.

Essential gases are passed through

The PO2 is fetus is 30. The PO2 in women in arteriole pressure is 100.

Fetal Hb steals the oxygen off of mom’s hemoglobin because of higher affinity.
Carbon dioxide from the baby goes to the mom, so she can get rid of it

Glucose—main fuel for the developing baby.
Amino acids and fatty acids go to the baby

(female reproductive system)

Gestational diabetes:

10% of the expected mother population
Very similar to type 2 diabetes (sensitivity problem)
More like to get type 2 diabetes later in life for the mom.
Really high blood sugars transferred to babies. Babies become huge due to hyperglycemia. The risk is that vaginal delivery is too difficult because the baby is too big. Glucose challenge test to check if a mom is a gestational diabetic.

Maternal blood flow

Maternal blood flow increases 40%
Increased blood goes throughout the body. That’s why the breasts enlarges and the skin glows when the mom is pregnant

Red blood cells, White blood cells and platelets are not passed through the placenta.

During delivery, blood can mix. That’s why Rogard is given to the mom. Rogard protects against Rh factor

Menopause

Decrease estrogen occurs.

Hot flashes occur, chances of osteoporosis increases, decreases vaginal secretion, and uterine glands are decreased

We don’t know the trigger of menopause. Estrogen therapy is not the treatment

Disease Conditions

Preeclampsia (5% of pregnancies)

Protein leave the blood and enters glomerulus. Protein clogs the filtration, and filtration can’t occur. Blood pressure starts to rise. Then the kidneys fail.

Eclampsia (less than 1%)

Vascular spasms occur, smooth muscle constrict
Incredibly high blood pressure
Systolic pressure can go up to 200 rather than the normal 120mmHg
Only treatment: deliver baby or abort baby or else mom dies.
Vasodilators are given to cause the vessels to try and open. Then women has to induce pregnancy

Surfactant—Doesn’t develop until the 7 month

Not enough surfactant causes respiratory distress syndrome. That’s why you avoid premature pregnancy

(female reproductive system)

Birth

Braxton Hicks contractions—false start labors. These are just rhythmic contractions
Oxytocin from posterior pituitary causes the real labor.

Hypothalamus signals posterior pituitary via Hypothalamo-hyposeal tract. Oxtocin goes through bloodstream and onto the myometrium. This is a positive feedback system. More oxytocin, then a stronger contraction.

Relaxin—softens the pubic symphisis andcervix and loosens ligaments and connective tissue.
Drug given to induce labor—Pitoccin (mimic of oxytocin)
Oxytocin trigger can be because of the fat accumulation in the baby

Lactation
The mammary glands are swelled. Estrogen and Progesterone inhibit milk production. After birth, Prolactin comes from the anterior pituitary which stimulates the mammary glands to make milk. The prolactin feed backs onto GnRH and shuts off the release. Now oxytocin is used for milk ejection which is caused by the reflex of suckling.

Neonates

Some things to watch out for:

Hypoglycemia (low blood sugars)—because they haven’t gotten nutrient from mom’s milk (mom’s milk isn’t produced yet). Baby feeds off of its own fat.

Signs: fatigue, lethargy, metabolism decrease, heart rate and breathing rate decreases

Jaundice

Yellowing of the skin because of buildup of bilirubin.
It is a build up bilirubin (made in the liver and spleen). Breakdown of red blood cells release bilirubin
Neonates are breaking down red blood cells because they have to convert fetal hB to adult hB. However, there is too much of the break down, and the liver and spleen are overwhelmed.
UV light of the sunlight treats jaundice

Maintaining temperature:

Brown fats are in the neonates allowing thermogenesis.

Remember there is more brown fat in neonates than adult.

(female reproductive system)
End of Human Reproductive System Notes

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