Unit 5 Reproductive system

Describe the structure structure of a mature sperm cell and explain the importance for each part.

spermatozoa: contains nucleus, acrosome and tail Head: -nucleus contains haploid set of chromosomes -Acrosome contains enzymes that penetrate the egg Tail: -midpiece contains mitochondria (produce ATP for flagellar movement)

What are the paramesonephric and mesonephric ducts? what is their function in the adult?

start with two sets of ducts: 1) Mesonephric duct develop into male reproductive system (paramesonephric ducts degenerate) 2) Paramesonephric ducts (mullein ducts) develop into female reproductive tract (mesonephric ducts degenerate)

Why is the blood-testis barrier important for sperm development?

we want to have a barrier between our blood cells and reproductive cells because if there is a crossover our body could make antibodies that our foreign to our reproductive cells and that would not be good for sperm development and reproduction

What is cervical cancer?

-Cancer of the cervix caused by the HPV virus -Symptoms: Pain during sex, pelvic pain, unusual bleeding or discharge -Rosk group: infection with HPV, having multiple sex partners, smokers, long term use of oral contraceptives

How does oogenesis differ from spermatogenesis?

1. During meiotic divisions, cytokinesis is unequal, with almost all of the cytoplasm in one daughter cell, the secondary oocyte 2. Unlike sperm, eggs are not produced continuously throughout life 3. Oogenesis has long "resting" periods, whereas sperm are produced in uninterrupted sequence

What happens at puberty in males and females and why? what hormones are involved and what is there effect?

Puberty in men: Reproductive system remains dormant for years after birth -surge of pituitary gonadotropins (FSH and LH) begins sexual development - release of testostrerone leads to secondary sex characteristics: 1)facial, pubic and chest hair 2) Deeper voice (larger larynx) 3) broader shoulders Puberty in Women: Triggered by rising levels of GnRH which stimulates anterior lobe of pituitary to produce FSH and LH (gonadotropins) - FSH stimulates follicles to secrete estrogen and progesterone *menarche=first menstrual period -Female hormones secreted cyclically and in a sequence -release of estrogen in puberty causes the development of secondary sex characteristics: breasts and broader hips

What substance in the urine would over the counter pregnancy tests test for? Explain

- The way that over-the-counter pregnancy tests (also called home pregnancy tests) work, is that they indicate whether or not your urine contains the human chorionic gonadotropin (hCG), or pregnancy hormone

What is Endometriosis?

-A condition in which endometrium growth takes place outside of the uterus - The endometrial tissues acts just like the endometrial lining of the uterus, it grows and sheds with each cycle but since the tissue is in the abdominal pelvic cavity it has no way to escape and it builds up over time -Symptoms: Pelvic pain, heavy periods, infertility -risk groups: Never giving birth, pelvic infections, family history

what are polar bodies? why are they important in females but not males?

-A polar body is a small haploid cell that is formed concomitantly as an egg cell during oogenesis, but which generally does not have the ability to be fertilized. -Polar bodies form because the egg cell (oocyte) does not divide evenly. The resulting cells have the same DNA, but one is much smaller, called a polar body. The cell with more cytoplasm becomes a mature ovum while the polar body usually dissolves.

What signaling molecules (hormones) are important in sexual determination/development? What do these hormones do to the developing fetus?

-Absence of testosterone and AMH (anti-mullerian hormone) causes degeneration of (male) mesonephric duct > Female -Presence of testosterone and AMH causes development of mesonephric and degeneration of Paramesonephric duct> male -Penis=clitoris -Penile skin=labia minora -scrotal skin=labia majora

Explain the Importance of sexual reproduction and recombination for the human species. Why is genetic diversity important?

-During sexual reproduction, meiosis generates genetic variation in offspring because the process randomly shuffles genes across chromosomes and then randomly separates half of those chromosomes into each gamete

How do the male and female gametes differ and why is this important?

-Female gametes are called ova or egg cells, and male gametes are called sperm. Gametes are haploid cells, and each cell carries only one copy of each chromosome.

Briefly explain the importance of oxytocin and prolactin in birth and lactation. What does each do? What is the importance of oxytocin in mother-infant bonding?

-High levels of endorphins in the mother pass on to the baby in her breast milk. -Prolactin and oxytocin are released in response to stimulation by the baby's sucking at the breast. Prolactin is responsible for milk production, and oxytocin for milk letdown. However, these hormones are beneficial in other ways. -Suckling causes release of Prl and oxygen fro anterior pituitary

What are the secretions of the accessory glands of the male and what function does each perform?

-It's made up from secretions from the three accessory glands. The seminal vesicles, the prostate and the bulbourethral glands all contribute to the production of semen. The seminal vesicles provide nutrients and mobility to previously immobile sperm

What causes menstruation to occur?

-Low levels of estrogen and progesterone trigger the Hypothalamus to release GnRH -If the egg is not fertilized, it will break apart. Then, hormone levels drop, and the thickened lining of the uterus is shed during the menstrual period. This occurs after hormone levels drop at the end of the previous cycle, signaling blood and tissues lining the uterus (womb) to break down and shed from the body.

Summarize oogenesis. Where and when does oogenesis occur?

-Monthly event producing single haploid egg -embryonic development 1. Germ cell differentiate into oogonia and multiply in number(millions made by mitosis) 2. start meiosis 1 and transform into primary oocytes then stop until puberty *most degenerate by childhood *by puberty 400,000 oocytes left -FSH stimulates completion of meiosis 1, produces secondary oocyte and 1st polar body 1. secondary oocyte goes into meiosis 11, ovulates and ceases until fertilization 2. after fertilization, completes meiosis 11 and releases 2nd polar body(only if sperm is present)

Why are the testes located in the scrotum? What three methods accomplish scrotal thermoregulation?

-Moving the testes away from the abdomen and increasing the exposed surface area allow a faster dispersion of excess heat. This is done by means of contraction and relaxation of the cremaster muscle and the dartos fascia in the scrotum. -The testes are located in the scrotum to provide a slightly cooler temperature necessary to produce sperm.

Describe the ovarian cycles. What is occurring during each? what are the different phases of each cycle? What hormones are important and why?

-Ovarian cycles: 1. Follicular phase: -menstruation occurs during the first 3 to 5 days of cycle -Follicles grow -uterus replaces lost endometrium 2. Postovulatory phase (egg that hasn't gone through meiosis 2 yet) -corpus lute stimulates endometrial thickening -endometrium lost if pregnancy does not occur 3. Menstrual: during discharge of menstrual fluid (days 1-5) 4. Preovulatory: refers to the stage of a woman's menstrual cycle between ovarian stimulation and ovulation. A woman is most fertile during the last few days of the periovulatory phase and the day of ovulation. The periovulatory phase is also called the follicular phase.

What are the primary, secondary and accessory structures of the male and female reproductive systems? Briefly talk about their functions.

-Primary sex organs of the male: gametes, testes that produce sperm Secondary sex organs of the male: Efferent ductules, epididymis, Vas deferent, Ejaculatory duct( Spermatic ducts), penis, etc. Accessory sex organs of the male: Seminal vesicle , prostate gland, bulbourethral gland -Primary sex organs of the female: gamete, Ovary where egg is produce secondary sex organs of the female: Internal genitalia (duct system, uterine tubes, uterus, vagina Accessory sex organs of the female: Clitoris, labia minor, labia majora

What is erectile dysfunction?

-Symptoms: inconsistent or total inability to maintain a firm enough erection for sexual intercourse -Risk groups: older men, obesity, smokers, diabetics, some medications (such as antidepressants), drugs and alcohol abuse

What is prostate cancer?

-Symptoms: problems during urination such as dribbling, and problems with starting and stopping the stream. Symptoms also include lower back pain and painful ejaculation -Risk groups: Men over the age of 65, family history, and African American men

Describe the brain-gonadal axis. How do the hormones in this axis interact to regulate the reproductive systems?

-The human male and female reproductive cycles are controlled by the interaction of hormones from the hypothalamus and anterior pituitary with hormones from reproductive tissues and organs. In both sexes, the hypothalamus monitors and causes the release of hormones from the pituitary gland. When the reproductive hormone is required, the hypothalamus sends a gonadotropin-releasing hormone (GnRH) to the anterior pituitary. This causes the release of follicle stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary into the blood.

Explain the functions of the uterine tubes. Why are these functions necessary?

-The uterine tubes, also known as oviducts or fallopian tubes, are the female structures that transport the ova from the ovary to the uterus each month. In the presence of sperm and fertilization, the uterine tubes transport the fertilized egg to the uterus for implantation.

How does the structure of the vaginal wall and surrounding erectile tissue contribute to reproductive function?

-The vaginal wall contains three layers: serosa (surface layer to avoid friction), muscularis (smooth muscle) and mucosa (lining). The mucous layer protects the woman from pathogens such as bacteria and viruses. The muscularis helps with reproduction because it facilitates birth with contractions and it provides "grip" during intercourse. Near the vagina are erectile tissues called the bulbs of the vestibule. The bulbs are vascular tissues on either side of the vagina that engorge with blood during arousal. This action narrows the vagina (again better "grip") and it also squeezes fluid out of the vaginal wall into the vaginal canal for lubrication during sex. This lubrication action is called transudation and is very important to avoid pain and tearing during intercourse.

Describe the uterine cycle. What is happening during it. What are the different phases of the cycle? what hormone are important and why?

-Uterine cycle: 1. Proliferative phase:(extra cells being made) -mitosis of endometrial layer thickens uterine wall in preparation for implantation 2. Secretory phase: -endometrial lining continues to thicken due to increase fluid secretion *proliferative phase; time of rebuilding of endometrial tissue lost at last menstruation, mitosis occurs in stratum basalis, results of estrogen from developing follicles *secretory phase; further thickening of endometrium due to secretion and fluid accumulation not mitosis, due to progesterone stimulation of secretory glands *progesterone level falls due to atrophy of corpus luteum

What is pelvic inflammatory disease?

-an infection of the female reproductive tract typically caused by gonorrhea or chlamydia - PID is the most common preventable cause of infertility in the US - Symptoms: abdominal pain, fever, irregular discharge - Risk groups: women under the age of 25, women with an STD/STI, women with an IUD. women with multiple sex partners - long term concerns: -PID can result in scar tissue in the Fallopian tubes which can increase a women chance of sterility and ectopic pregnancies

What is Polycystic Ovary Syndrome (PCOS)?

-occurs when women hypersecretes male hormones resulting in the development of fluid filled sacs in the ovaries -Common disorders that affects 1 in 10 women of child bearing age -Symptoms: hair growth on face, infertility (most common cause of infertility in women), irregular periods, pelvic pain, thinning hair -Risk groups: family history, obesity

Compare and contrast the male and female sexual response.

1) Female sexual response: Excitement and plateau -initiated by many different erotic stimuli -excitement is characterized by vasocongestion of gentials and increases heart rate, BP, and pulmonary ventilation -erection is due to parasympathetic triggering of nitric oxide and acetylcholine secretion 2) Male sexual response: -blood supply come from dorsal artery and lacunae of corpora cavernosa fill and cause erection -parasympathetic signals produce an erection with direct stimulation of the penis and other perineal organs -excitement is characterized by vasocongestion of genitals and increases in heart rate, BP and pulmonary ventilation -parasympathetic triggering of nitric oxide and acetylcholine secretion -erection is maintained during plateau phase

What structures are analogous(similar) in males and females?

1) Genital tubercle: turns into for the male a penis, bulb penis and glans penis Female turns into: clitoris, vestibular bulb 2) Urogenital fold: male; penile skin female; labia minora 3) Labioscrotal fold: male; scrotal skin Female; labia majora

What are the 3 layers in the uterus? What function does each layer perform?

1)The endometrium is the inner layer that lines the uterus. It is made up of glandular cells that make secretions. 2)The myometrium is the middle and thickest layer of the uterus wall. It is made up mostly of smooth muscle. 3)The perimetrium is the outer serous layer of the uterus.

Describe how the relevant hormones regulate the different phases of the female cycles.

1. Estrogen: Rising levels of estrogen are responsible for the build up of the uterine lining (endometrium). 2. Follicle-stimulating hormone: This hormone is made by the pituitary gland. Its purpose is to get a follicle ready for ovulation. Every month between 3 and 30 follicles are ripened for ovulation but usually only one continues to grow and eventually ruptures and releases an egg during ovulation. 3. Luteinizing hormone: This is the hormone that makes the egg (follicle) release from the ovary. This hormone is involved in the process of ovulation - the time in the menstrual cycle when the follicle ruptures and releases the egg from the ovary. 4. Progesterone:This hormone is released by the ruptured follicle (one that has released an egg). After the egg is released from the follicle, the follicle closes and becomes a corpus luteum. The corpus luteum secretes increasing amounts of progesterone.

What are chromosomes and sister chromatids? Discuss their role in mitosis and meiosis.

A sister chromatid refers to the identical copies formed by the DNA replication of a chromosome, with both copies joined together by a common centromere. In other words, a sister chromatid may also be said to be 'one-half' of the duplicated chromosome. -The two sister chromatids are separated from each other into two different cells during mitosis or during the second division of meiosis.

How does birth control work?

Administration of estrogen or progesterone (or both, but usually estrogen) given at significant levels during the first half of the ovarian cycle suppresses ovulation. It suppresses the LH surge.

What are the components of semen? What is the function of each component?

Components of semen: -Fructose: provide energy for sperm motility (seminal vesicle) - Fibrinogen: causes clotting (seminal vesicle) - Fibrinolysin: liquefies semen within 30 minutes (prostate) - Prostaglandins: stimulate female peristaltic contractions (seminal vesicle) - Spermine: is a base stabilizing sperm pH at 7.2 to 7.6 (prostate)

What is the difference between emission and expulsion during ejaculation?

Ejaculation: 1) Emission: Sympathetic nervous system propels sperm through ducts as glandular secretions are added 2) Expulsion: semen in urethra activates muscular contractions that lead to release of semen

What are gametes? Why are they unique among cells?

Gametes are an organism's reproductive cells. They are also referred to as sex cells. -Why gametes are unique: Genetic variation is increased by meiosis. During fertilisation, 1 gamete from each parent combines to form a zygote. Because of recombination and independent assortment in meiosis, each gamete contains a different set of DNA.

Briefly describe the hormonal changes that occur In response to fertilization and implantation. What structure does hCG target?

Hormonal changes during pregnancy: 1) Implanted zygote produces human chorionic gonadotropin (HCG) main hormone to pregnancy 2) Corpus lute continues to produce estrogen and progesterone during 1st trimester 3) As placenta develops, ovaries produce less estrogen and progesterone 4) By 3rd trimester, corpus lute degraded and all hormones coming from placenta

How is the sex of an offspring determined?

In the XY sex-determination system, the female-provided ovum contributes an X chromosome and the male-provided sperm contributes either an X chromosome or a Y chromosome, resulting in female (XX) or male (XY) offspring, respectively. Hormone levels in the male parent affect the sex ratio of sperm in humans.

How do the male and female reproductive systems differ? How are they alike?

Male and female reproductive systems: -Similarities: both primary organs are the produce gametes (sperm and egg) The gonads produce gametes (eggs or sperm) which unite during fertilization. They also produce steroid hormones essential for reproduction as well the growth and development of the entire body. The genitalia are the external reproductive structures (penis in males, clitoris and vulva in females). -Differences: The male reproductive system consists of external organs. The testes in the scrotum produce the male gamete, sperm, which is ejaculated in seminal fluid by the penis. ... The female gamete, ovum, is produced in the ovaries and is released monthly to travel to the uterus via the Fallopian tubes.

Describe the hormonal interactions in the female and male. How do these interactions differ?

Male hormonal regulation: 1. GnRH stimulates secretion of FSH and LH 2. FSH stimulates Sertoli cells to release androgen binding protein(ABP) and stimulates sperm production, inhibits additional secretion of GnRH, LH, and FSH 3.LH stimulates interstitial cells to produce testosterone; inhibits additional secretion of GnRH, LH and FSH, inhibits FSH released when sperm count is high Female hormone regulation: 1. GnRH stimulates secretion of FSH and LH 2. FSH stimulates ovarian follicular cells to develop ovum and produce estrogen 3. LH stimulates ovarian follicle cells to burst (ovulation);follicle develops into corpus lute 4. Follicle produces estrogen; corpus lute produces progesterone and some estrogen which regulate hormonal secretion from the hypothalamus and APG

Compare and contrast mitosis and meiosis. Explain how both processes contribute to the formation of gametes.

Mitosis: Produces two genetically identical diploid daughter cells -Purposes: replacement of old cells, growth of the body, repair of body tissues Meiosis: Produces haploid gametes -Purpose: sexual reproduction *Diploid= 2 sets of chromosomes (1 set from each of your parents) diploid in humas is 46 chromosomes which is 23 pairs * Haploid= 1 set of chromosomes (1 set you will provide to your offspring in your sex cell) haploid in humans is 23 chromosomes

Describe the effects of estrogen and progesterone on the uterus, hypothalamus, and pituitary.

Progesterone is secreted to prevent uterine contractions that may disturb the growing embryo. The hormone also prepares the breasts for lactation. Increased estrogen levels near the end of pregnancy alert the pituitary gland to release oxytocin, which causes uterine contractions.

Explain the function of the different different cells (germ cells, Sertoli cells and interstitial cells) within seminiferous tubules.

Sperm production in testes: -testes are divided into seminiferous tubules where sperm are produced -each tubule is lined with a germinal epithelium composed of germ cells (gamete producing stem cell) -Steroli cells promote sperm cell development (blood-testis barrier is formed by tight junctions between Sertoli cells) -Interstitial cells: produce testosterone

Summarize spermatogenesis. Where does spermatogenesis occur?

Spermatogenesis is the process by which the male gametes, called sperm, are created. Spermatogenesis takes place in the seminiferous tubules

Describe the steps of fertilization.

Steps of fertilization: 1) egg is fertilized in ampulla of uterine duct 2) Acrosome digests zona pellucida surrounding egg 3) Proteins on head of sperm bind to receptors on egg 4) Nucleus of sperm injected into egg; fertilization membrane forms 5) Egg completes meiosis 11 6) Fertilization is not complete until the chromosomes of the sex join cells join in the nucleus

Explain how the Y chromosome determines sex in an individual- be sure the discuss SRY.

The SRY gene is found on the Y chromosome. The sex-determining region Y protein produced from this gene acts as a transcription factor, which means it attaches (binds) to specific regions of DNA and helps control the activity of particular genes. This protein starts processes that cause a fetus to develop male gonads (testes) and prevent the development of female reproductive structures (uterus and fallopian tubes).

What are the functions of the human reproductive system? Specifically, what are the male contributions to these functions? What are the female contributions?

The female reproductive system has two functions: to produce egg cells, and to protect and nourish the fetus until birth. The male reproductive system has one function: to produce and deposit sperm. Humans have a high level of sexual differentiation.

Briefly describe how the testes descend into the scrotum? What three methods accomplish scrotal thermoregulation?

Three methods accomplish scrotal thermoregulation: 1) cremaster muscle: segments of internal oblique muscle that pull testes closer to body 2) Dartos muscle: smooth muscle wrinkles skin reducing surface area 3) Venous plexus: veins ascending near testicular artery *countercurrent heat exchanger cools arterial blood entering the testis