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02 Chemical Aspects of Physiology
03 Cell Physiology
07 Respiratory Physiology
09 Nervous System
10 Sensory Organs
11 Muscle Physiology
15 Reproductive Physiology
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15 Reproductive Physiology
A certain gene on the Y chromosome induces the embryonic gonads to become testes. Females lack a Y chromosome, and the absence of this gene causes the development of ovaries. The embryonic testes secrete testosterone which induces the development of male accessory sex organs and external genitalia. The absence of the testes in a femaleembryo causes the developmentof the female accessory organs.
Endocrine Regulation of Reproduction:
The functions of teh testes and ovaries are regulated by gonadotropic hormones secreted by the anterior pituitary. The gonadotropic hormones stimulate the gonadsto secrete their sex steroid hormones, in turn, have an inhibitory effect on the secretion of the gonadotropic hormones.
Male Reproduction System:
The Leydig cells of the testes secrete testosterone, which stimulates the male accessory sex organs, promotes the development of make secondary sex characteristics, and is needed for spermatogenesis. LH stimulates the Leydig cells, whereas FSH stimulates the Sertoli cells of the seminiferous tubules.
Female Reproductive System
Some ovarian follicles mature during the ovarian cycle, and the ova they containprogress to the secondary oocyte stage of meiosis. At ovulation, the secondary oocyte is released from the ovary. The empty follicle then becomes a corpus luteum, which ultimately degenerates at the end of a nonfertile cycle.
Cyclic changes in the secretion of gonadotropic hormones from the anterior pitutary cause the ovarian changes during a monthly cycle. The ovarian cylcleis accomplised by cyclic changes in the secretion of estradiol and progesterone, which cause changes in the endometrium of the uterusduring a menstrual cycle.
FERTILAIZATION, PREGNANCY AND PARTURITION
Once fertilization has occured, the secondary oocyte completes meiotic division. It then undergoes mitosis and forms an early embryonic strucute called a blastocyst. Cells of the blastocysts secrete human chorionic gonadotropin, a hormone that maintains the mother's corpus luteum and prevents menstration. Birth is dependent upon strong contractions of the uterus, which are stimulated by oxytocin.
Sexual reproduction, germs cells or gametes are formed within the gonads by a processof reduction division or meiosis. The normal number of chromosomes in a human cell is 46..each gamete recieves 23..fusion of trhe sperm and ovum in the act of fertilization results in restoration of the original number. Each zygote recieves 23 chromosomes from its mother and 23 from the father..this does not 46 different chromosomes but rather 23 pairs of homologous chromosomes.
The 23rd pair of chromosomes are the sex chromosomes..In females this is the "x" chromosome and in males it is the "y" chromosome..
Male Reproductive System
In the human reproductive process, two kinds of sex cells, or gametes, are involved. The male gamete, or sperm, and the female gamete, the egg or ovum, meet in the female's reproductive system to create a new individual. Both the male and female reproductive systems are essential for reproduction.
Most species have two sexes: male and female. Each sex has its own unique reproductive system. They are different in shape and structure, but both are specifically designed to produce, nourish, and transport either the egg or sperm.
Unlike the female, whose sex organs are located entirely within the pelvis, the male has reproductive organs, or genitals, that are both inside and outside the pelvis.
The male genitals include: the testicles, the duct system, which is made up of the epididymis and the vas deferens, the accessory glands, which include the seminal vesicles and prostate gland, and the penis.
Alongside the testicles are the epididymis and the vas deferens, which make up the duct system of the male reproductive organs. The epididymis and the testicles hang in a pouch-like structure outside the pelvis called the scrotum. This bag of skin helps to regulate the temperature of testicles, which need to be kept cooler than body temperature to produce sperm.
The accessory glands, including the seminal vesicles and the prostate gland, provide fluids that lubricate the duct system and nourish the sperm. The seminal vesicles are sac-like structures attached to the vas deferens to the side of the bladder. The prostate gland, which produces some of the parts of semen, surrounds the ejaculatory ducts at the base of the urethra, just below the bladder. The urethra is the channel that carries the semen to the outside of the body through the penis. The urethra is also part of the urinary system because it is also the channel through which urine passes as it leaves the bladder and exits the body.
The penis is actually made up of two parts: the shaft and the glans. The shaft is the main part of the penis and the glans is the tip (sometimes called the head). At the end of the glans is a small slit or opening, which is where semen and urine exit the body through the urethra. The inside of the penis is made of a spongy tissue that can expand and contract.
A male who has reached puberty will produce millions of sperm cells every day. Each sperm is extremely small: only 1/600 of an inch (0.05 millimeters long). Sperm develop in the testicles within a system of tiny tubes called the seminiferous tubules.
The sperm then move to the vas deferens, or sperm duct. The seminal vesicles and prostate gland produce a whitish fluid called seminal fluid, which mixes with sperm to form semen when a male is sexually stimulated.
Semen is pushed out of the male's body through his urethra — this process is called ejaculation. Each time a guy ejaculates, it can contain up to 500 million sperm. When the male ejaculates during intercourse, semen is deposited into the female's vagina. The genetic material from the male and female has combined so that a new individual can be created. The zygote divides again and again as it grows in the female's uterus, maturing over the course of the pregnancy into an embryo, a fetus, and finally a newborn baby.
human physiology book
Female Repoductive System
Resources Physiology Book Ch 20
The two ovaries are suspended by ligaments from the pelvic girdle, and are partially covered by fimbriae from the uterine tubes. The ova are released from the ovaries and travel to the uterine tubes by ciliated epithelial cells. The lumen is continuous with the uterus. The uterus is made up of three layers; perimetrium, myometrium, and endometrium. The endometrium has a stratified, squamous nonkeratinized epithelium called the stratum functionale. The stratum functionale grows thicker during a cycle and sheds at menstruation. The uterus narrows to form the cervix, and the cervix opens into a tube called the vagina. These three are the accessory organs of the female reproductive system. The vaginal opening is posterior to the urethra, and contains folds called labia minora and labia majora. The clitoris is composed of erectile tissue and is located on the anterior portion of the labia minora.
In prenatal life, the germ cells that move into the ovaries multiply and at 5 months the ovaries can contain anywhere from 6 to 7 million oogonia. Most of the oogonia die through apoptosis during prenatal life. The remaining oogonia go through meiosis at the end of prenatal life and become primary oocytes. The oocytes are diploid. When a female is born she contains 2 million oocytes which are in ovarian follicles. By puberty the oocytes have reduced even more to 400,000, but only 400 of those are ever released during ovulation, the rest die through apoptosis. The number of oocytes a female is born with is all she will produce her entire life. The primary oocytes that have not been released during ovulation are kept in primary follicles. When the primary oocyte goes through its first meiotic division it does not produce two complete cells. One cell becomes the secondary oocyte and gets the cytoplasm. The other becomes a small polar body. The secondary oocyte begins the second meiotic division but is stopped at metaphase II, if not fertilized.
10 to 14 days after the first menstruation day one of the follicles containing an oocyte matures fully. This follicle bulges out of the ovary and under hormonal stimulation ruptures. After the follicle ruptures, the oocyte is extruded toward the uterine tube, this process is called ovulation. If the oocyte is not fertilized it regresses by going through structural and biochemical changes and becomes a corpus luteum. The corpus luteum secretes two sex steroid hormones; estradiol and progesterone. At the end of the nonfertile cycle, the corpus luteum regresses into a nonfunctional corpus albicans.
The menstrual cycle is a monthly cycle of ovarian activity. Menstruation is when the stratum functionale of the endometrium is shed from the uterus. Bleeding accompanies the shedding of the stratum functionale and is caused by a fall in estrogen and progesterone secretion. There are three phases of the ovaries in the menstrual cycle: follicular phase, ovulation, and luteal phase.
The follicular phase lasts from day 1 to day 13. In this phase one of the ovarian follicles becomes mature. The growth of the follicle is and secretion of estradiol is stimulated by FSH. FSH and estradiol stimulate production of FSH receptors on the follicle. At the end of the follicular phase FSH and estradiol stimulate the production of LH receptors on the follicle. There is an increase in LH secretion, at the end of the phase, which creates a LH surge that begins 24 hours before ovulation and is at its peak 16 hours before ovulation.
Ovulation is the second phase in ovaries. The follicle has grown into a bulge at the end of the over that bursts when the LH surges. The second oocyte is released from the ovary and carried by cilia to the uterine tube. Once in the uterine tube it starts its way down the tube to the uterus.
The last phase is the luteal phase. The empty follicle is stimulated by LH to become a corpus luteum that secretes estradiol and progesterone. The secretion of estradiol and progesterone together inhibit the secretion of FSH and LH, this this stops new follicles from developing during this phase. Throughout the phase the function of the corpus luteum declines and levels of estrogen and progesterone fall. By day 28 the withdrawal of sex steroids causes menstruation and a new follicle cycle to begin.
There are also cycle changes in the endometrium of the uterus. There are three phases of the endometrium: proliferative, secretory, and menstrual. The proliferative happens during the follicular phase of the ovaries. The increase of estradiol promotes the growth of the endometrium; also spiral arteries develop inside the endometrium. The secretory phase occurs during the luteal phase of the ovaries and progesterone is increased. The increase in progesterone stimulates development of uterine glands. During this phase the endometrium becomes thick, vascular, and spongy. The combination of the uterine glands and thick, vascular appearance prepares the uterus to support an embryo. The final cycle is the menstrual cycle and it begins because of a fall in ovarian hormones. Constriction of the spiral arteries causes cellular death and the stratum functionale to begin to shed.
Fertilization, Pregnancy, and Parturition
During intercourse, the male ejaculates about 300 million sperm into the vagina, but only about 100 survive to enter each fallopian tube. About 10% of those are able to fertilize an ovum (capacitation). The capacitated sperm move up the oviduct toward the ovum by chemotaxis (attraction to certain chemicals) and thermotaxis (attraction to warmer temps).
Fertilization usually happens in the uterine tubes. The sperm has an enzyme-filled vesicle called an acrosome. When the sperm interacts with certain molecules in the zona pellucida, an acrosomal reaction is triggered. This involves the creation of pores so acrosomal enzymes can exit by exocytosis. These enzymes allow the sperm to make a path to the oocyte.
Fertilization stimulates the oocyte to release stored Ca2+. This rise in cytoplasmic Ca2+ causes a Ca2+ wave. In 2 seconds the wave will spread from one side of the oocyte to the other. The wave activates the fertilized egg. Within 12 hours, the chromosomes from the ovum are joined with the chromosomes from the sperm cell, creating a zygote (fertilized egg).
36 hours after fertilization the zygote divides by mitosis (cleavage). A second cleavage at 40 hours occurs, and another at 60 hours, making a ball of eight cells (morula). This enters the uterus three days after ovulation. Cleavage continues until the morula has about 64 cells by the fourth day. It is then made into a blastocyst. The inner cell mass of the blastocyst will be the fetus, and the chorion will be part of the placenta.
On the sixth day, the blastocyst attaches to the uterine wall and implantation begins. By the seventh day the blastocyst is buried in endometrium. The blastoyst secrets chorionic gonadotropin which is able to keep the corpus luteum past the normal amount of time.
Decidual reaction is when the blastocyst develops and changes. The chorion frondosum (fetal tissue) and decidua basalis (maternal tissue) make up the placenta. By the end of the second trimester spiral arteries have been changed to dilated tubes, so maternal blood flows into the placenta.
Underneath the chorionic membrane is the amnion which is where the embryo grows (amniotic sac). (Genes can be tested for abnormalities with a process called amniocentesis.
The umbilical arteries brings fetal blood to vessels in the placenta. After it circulates it returns to the fetus through the umbilical vein. Gases are exchanged in the placenta between maternal/fetal blood. The placenta secrets steroid and protein hormones. After the first 5 and a half weeks, the corpus lluteum starts to regress and the placenta becomes the main sex-steroid-producing gland. For the placenta to make estrogen, it needs to cooperate with steroid making tissue of the fetus. Tee placenta and fetus make a single function system called the fetal-placental unit.
Contractions of the uterus to expel the fetus is known as labor. Contractions can be stimulated by oxytocin and prostaglandins. In animals parturition is helped by a hormone called relaxin. The hormone doesn't seem to be needed for parturition in humans, but does promote the growth of blood vessels in the decidua basalis. After delivery, oxytocin is needed to reduce hemorrhaging.
Secretion of prolactin stimulates the mammary glands to make milk proteins. After parturition, estrogen levels decrease and prolactin secretion increases, stimulating milk production.
Bobbi: for my role as a nurse, reproduction and the process will be something I deal with a lot. When dealing with females, one of the first questions you ask them is the first day of there last menstrual cycle and if it was normal to help rule out the possibility of pregnancy right away. I will also deal with the diverse people that a disorder in the embryonic stage like that of Downs syndrome or Spinabifida. Understanding human reproduction also plays a huge role in how the body develops also from the very first formation of the oocyte to the baby.
This chapter also helps me understand in depth why my body works they way it does throughout the month and the factors that cause it to do these things. I think by far the female body is way more complex and harder to decode than that of the male. a lot of females I have come across at a fairly good age early20's still do not know just exactly how the monthly calendar works as to which days are the best and worst to get pregnant!
Heidi: When working in the medical field, it's always good to know as much as possible about how humans 'work'---including reproduction. In the Occupational Therapy field it's possible that we may treat pregnant patients. It's important for us to know precautions that go along with that so that we can properly adapt our equipment/techniques.
Jacky: working as an OTA i will be teaching others about personal care devices. I will be able to inform others about sexual reproduction. I also will be able to inform females on how to properly use sanitary napkins. I also think that we will be able to work with women who are pregnant. I think that it is important to know about sexual reproducation when going into any health field
Sarah: The reproductive system was an interesting chapter. I learned the most from the female reproductive system portion. In the past, I have had extremely painful menstrual cycles and have been on birth control to control my hormones so that the cycles are less intense each month. After reading this part in the chapter I gained knowledge of how the birth control pill works to control those hormones. I think it especially important for females and males to have a general knowledge of how their systems so that they can determine if something is not working proper and know that they need to see a doctor about it. I know I went a few years dealing with extremely painful menstrual cycle and not knowing that something as simple as birth control would make a huge difference. It was not until my doctor told me that it was abnormal for pain to be so severe that I could barely get out of bed. Now with the help of my birth control I can function normally when my menstrual cycle comes around.
Jen: I enjoyed this section very much. After being pregnant for nine months you know great changes are going on but it was very interesting to hear the in depth details of what is happening. It is amazing to think we all started as a ball of cells. When working as an OTA is will be working with patients who are pregnant. I know I was not able to perform everyday tasks while pregnant, such as tying my shoes.
Describe the ovarian cycle and menstrual cycle. Describe what happens in
each stage and the role of hormones. Include these terms in your description:
follicular, ovulation, luteal, proliferation, secretory, menstrual, estradiol
(estrogen), FSH, LH, GNRH, progesterone, follicle, corpus luteum, endometrium
A germ cells that moves into the ovary during early embyonic developmentmultiply so that by about five onths of gestation the ovaries contain about 6-7 million oogonia, most die prenatally by apoptosis. The restbegin meiosis toward the end of gestation at which they are called primary oocytes and are still diploid. Primary oocytes that do not complete the first meiotic divison are contained within tiny primary follicles. Immature primary follicles consist of only a single layer of follicle cells. In response to FSH stimulation, some of these oocytes and follicles get larger and follicular cells divide to make more granulosa cells that surrond the oocyte and fill the follicle, some of these will grow more and develope a number of fluid filled cavities called vesicles and it now becomes a secondary follicle. As the follicle develops, the primary oocyte completes its first meiotic division. The secondary oocyte then begins the second meiotic division, but meiosis is stopped at metaphase two. The second meiotic division is completed only by an oocyte that has been fertilized. The secondary oocyte, stopped at metaphase II, is held in a graafian follicle. The granulosa cells of this follicle form a ring around the oocyte and form a mound the supprots it. between the oocyte and the corona radiata is a thin gel like layer of proteins and polysacchrides called the zona pellucida wich creates a barrier to the ability of a sperm to fertilize an egg.
2.The average menstraul cycle is 28 days in length. the actual act of menstration lasts from day 1 to day 4 or 5. During the follicular phase of the cycle, the ovarian follicles are stimulated by FSH from the anterior pituitary. Under FSH stimulation these follicles get bigger more mature and secrete increasing amounts of estradiol. At day 13, the rapid rise in estradiol secretionstimulates a surge of LH from the anterior pituitary and the granulosa cells during the follicular phase acts on the hypothalamusto increase frequency of the GnRH pulses., this surge stimulates ovulation at about day 14. After ovulation, the empty follicle is stimulated by LH to become a corpus luteum, at which point the ovary is in the luteal phase. Progesterone and estradiol rises during the first part of this phase and creates a negative feedback on FSH and LH secretion. Without this continued stimulation by LH, the corpus luteumregresses at the end of the luteal phase and the secretion of progesterone and estradiol decrease causing menstration.
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