please help me, I am having so much trouble with these questions. I have some in
ID: 270796 • Letter: P
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please help me, I am having so much trouble with these questions. I have some information, but I am not sure if I have it right or well put together. I would appreciate it. thank you so much!
8 12141 e..d 38% 2:11 PM a. All enzymes and chemicals used and where they are secreted. b. Regulation of gastric and pancreatic secretion. c. Movement of foodstuffs through the Gl tract. d. Defecation reflex 4. In Lord of the Rings: Return of the King, Arwen has a vision of the future wherein she and Aragorn have a son. Although fictional characters, both Arwen and Aragorn's reproductive systems are remarkably like ours. Answer the following questions about reproductive physiology and the female cycle. What is the hypothalamic pituitary gonadal axis? Discuss how this axis regulates gamete formation and release of sex hormones in each sex. Indicate which mechanism(s) are positive and which are negative feedback loops. a. b. Describe the process of spermatogenesis Discuss the menstrual cycle. Include the events/phases in both the ovary and uterus, what occurs if the egg is fertilized or not fertilized, and the hormones involved C.Explanation / Answer
The hypothalamus-pituitary-gonadal axis is a complex network of endocrine glands which govern the development and regulation of several body organs. it includes the array of feedback loops which help in regulating various processes.
This axis works distinctly in male and female.
Male:
The GnRH is a hormone secreted y hypothalamus.
GnRH travels to the anterior pituitary gland, which causes the release of LH and FSH hormones.
These two hormones travel through the bloodstream to reach testicles.
LH stimulates the Leydig cells of the testis to produce and secrete testosterone.
FSH stimulates the Sertoli cells to produce androgen binding globulin and inhibin.
Inhibin acts as a negative feedback loop which decreases the secretion of FSH, LH and GnRH. The testosterone also negative impacts the pituitary and hypothalamus.
Female:
In the female, the overall pathway remains the same, except the hormones. The LH and FSH bind to ovaries and stimulate the secretion of oestrogen and inhibin. oestrogen regulates the menstrual cycle and release of an egg. The inhibin and oestrogen negatively impact their own secretion. They at higher concentration inhibit the secretion of FSH, LH and GnRH.
b. Spermatogenesis: This is the process of development of sperm in the testis. The testis consists of different type of cells which take part in production and nourishment of sperm cells. The Immature sperm is derived from stem cells in seminiferous tubules. These cells divide by mitosis to keep a supply of immature sperm cells. These cells are still 2n condition and are called primary spermatocytes. These undergo meiosis to produce secondary spermatocytes after meiosis 1.
After meiosis 2, they form 4 mature spermatids which have only one copy of genome (n). They further differentiate into tailed sperms ( spermatozoa). These sperms are ready to meet the egg.
c. The menstrual cycle is the monthly event in the ovary of a female. This essentially is the shedding of unfertilized egg along with the endometrium. This process if energy consuming and hence painful and involves bleeding.
These are different stages of a menstruation cycle.
1. Follicular stage ( before the egg is released)
2. Ovulatory stage ( egg released)
3. Luteal stage ( after the egg is released)
Follicular stage: The preparation stage. Here the endometrium is prepared to nourish the fertilized egg. The pituitary gland releases FSH hormone. This hormone stimulates the follicle production from ovaries. only one of the follicle continues to grow and produce estrogen. The increased levels of estrogen stimulate the luteinizing hormone (LH) secretion.
If fertilization does not take place, the endometrium is shed and menstrual bleeding occurs.
Ovulatory stage: The LH hormone levels increase and stimulate the follicles to release the egg. This egg can be fertilized only up to 12 h after the release. Intercourse within 3 days of the release of the egg can result in pregnancy.
Luteal phase: This phase begins after ovulation. It lasts until next follicle stage if no fertilization has taken place. The follicle forms a structure called corpus luteum. this produces the higher concentration of progesterone. This hormone prepares the corpus luteum for embryo implant if fertilization has taken place. During this phase, the levels of estrogen in high, which stimulates the thickening of the endometrium. The rise in estrogen and progesterone can cause the milk ducts to dilate and as a result, breast becomes tender.
If the egg is not fertilized, then the corpus luteum degenerates within 14 days reducing the levels of hormones. A new cycle sets in.
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