Biology Chapter 15 Reproductive system of humans

Describe uterus.

Uterus is a thick and muscular organ that is lined up with endometrium tissue. Endometrium cells secretes mucus and rich in blod vessel.

Describe Fallopian tube.

Fallopian tube is a thin, muscular tube and its internal layer is covered with cilium. The action of cilium and peristalsis deliver the secondary oocyte or embryo to the uterus.

Describe ovary.

Ovary secretes oestrogen, progesterone, and ovum.

Describe cervix.

Cervix is a narrow opening that secretes mucus to aid the sperm entering the vagina.

Describe vagina.

Vagina is a canal that involves birth and excretion of urine and menstruation.

Describe seminal vesical.

Seminal vesicle secretes nutrient to the sperm.

Describe prostate gland.

Prostate gland secretes nutrients that smooth the movement of sperm.

Describe testes.

Testes secretes testosterone and sperm.

Describe scrotum.

A sac that protects the testes.

Describe urethra.

Urethra is a channel that involve excretion of sperm and urine.

Describe penis.

Penis is the organ that enters the vagina to release sperm into it.

Describe sperm duct.

sperm duct transport the sperm.

What are the two type of gametogenesis?

Gametogenesis involves spermatogenesis and oogenesis.

Where does spermatogenesis located at?

Seminiferous tubule.

What cells of the wall of seminiferous tubule provide nutrient to the sperm?

Sertoli cells

Explain the process of spermatogenesis.

Primordial germ cell will undergo mitosis forming spermatogonium. Spermatogonium will develop into diploid primary spermatocyte. Primary spermatocyte will undergo meiosis 1 to produce two haploid secondary spermatocytes. The haploid spermatocytes will undergo meiosis 2 to produce 4 haploid spermatids. The spermatids will undergo differentiation to produce 4 haploid sperm cells.

Explain the process of oogenesis.

During birth, primary germ cell will undergo mitosis to produce oogonium. Oogonium will develop into diploid primary oocyte. The primary oocyte is encapsulated by primary follicle that is stimulated by the FSH hormone. Primary oocyte will undergo meiosis 1 but stops at prophase 1.

At birth, the production of primary oocyte is stopped. The foetus currently produced a large number of primary oocyte but the number will gradually decrease.

At puberty, the diploid primary oocyte will completely undergoes meiosis 1 producing a haploid secondary oocyte and a haploid primary polar body. The haploid polar body will undergo meiosis 2 to produce two haploid polar body that will be degenerated and absorbed by the body. The haploid secondary oocyte will undergo meiosis 2 but stops at metaphase 2. The primary follicle will develop into secondary follicle and into Graafian follicle that is stimulated by the FSH hormone. The Graafian follicle will moves towards the ovary and releasing the secondary oocyte. The remaining follicle will develop into corpos luteum.

When fertilization does not occur, The corpos luteum, secondary oocyte and endometrium wall will degenerate and excreted through menstruation.

When fertilization occurs, the secondary oocyte will completely undergo meiosis 2 forming ovum and a polar body that will be degenerated and absorbed by the body. The ovum will fuse with the sperm forming zygote. The corpos luteum will continue to secrete oestrogen and progesterone, endometrium wall will continue to thicken.

What are the hormones involved during menstruation and what is their function?

Follicle-stimulating hormone will stimulate follicle growth and stimulate the secretion of oestrogen.

Luteinizing hormone will stimulate ovulation and the formation of corpos luteum and stimulate the secretion of progesterone.

Oestrogen will thicken the endometrium wall and stimulate the secretion of FSH and LH before ovulation.

Progesterone will thicken the endometrium wall, stimulate the formatio of blood capillaries and stops the secretion of FSH and LH.

Explain the whole menstrual cycle.

During day 0-5, the corpos luteum will degenerate due to low level of LH that causes low level of oestrogen and progesterone to be produced. The endometrium wall will shed and menstruation occurs. The hypothalamus detects and secretes gonadotrophin-releasing hormone to the pituitary gland and secrets LH and FSH. FSH stimulates growth of new follicles that produces oestrogen. Low level of oestrogen inhibits the secretion of FSH and LH via negative feedback mechanism.

During day 5-14, the level of oestrogen peaks at day 12,causing the hypothalamus to secrete gonadotrophin-releasing hormone that stimulates the releasing of LH from the pituitary gland via positive feedback mechanism. Level of LH peaks during day 13 that causes 14 to ovulate. The Graafian follicle will release the secondary oocyte , and the remaining follicle will develop into corpos luteum through LH.

During day 15-21, corpos luteum will produced oestrogen and progesterone. The combination of oestrogen and progesterone will inhibit the secretion of LH and FSH via negative feedback mechanism. Progesterone will thicken and enriching the endometrium wall with blood capillaries for implantation.

During day 22-28, if fertilisation occurs, The ovum will fuse with the sperm forming zygote. The corpos luteum will continue to secrete oestrogen and progesterone so the endometrium wall will continue to thicken. If fertilisation does not occur, The corpos luteum will degenerate due to low level of LH and causes the level of oestrogen and progesterone to drop. The endometrium wall will shed and menstruation begins.

What is premenstrual syndrome.

Premenstrual syndrome is when the level of oestrogen and progesterone is imbalance throughout the menstrual cycle.

What is menopause.

Menopause is the halting of formation of ovum due to ovulation and menstruation stops naturally that causes low level of oestrogen and progesterone.

What is the sequence of growth of fertilized cell?

zygote → morula → blastocyte → Embryo

What is human chorionic gonadotrophin hormone?

Human chorionic gonadotrophin hormone is a type of hormone that ensures the corpos luteum to continue secreting oestrogen and progesterone during early stage of pregnancy.

What does the umbilical artery transfers?

Umbilical artery transfers deoxygenated blood and nitrogenous waste from the foetal circulation system to the mother circulation system.

What does the umbilical vein transport?

The umbilical vein transport oxygenated blood and nutrients from the mother’s circulation system to the foetal circulation system.

What is the function of placenta.

Placenta acts as the site in exchanging substances between the foetus and the mother.

Why does the mother and foetus blood dont mix.

It is to prevent toxic substances in the mother’s blood from entering the foetal circulation system.

It prevents the vessel of the foetus from ruptering due to the mother’s high blood pressure.

To prevent agglutination when the foetus blood and the mother’s blood do not match.

Types of twins

Identical twins and fraternal twins

what causes male impotency?

Hormonal imbalance, testes does not produce sperm

What causes female impotency?

Hormonal imbalance, ovaries does not produce ovum

How to treat sexual impotency?

Hormonal therapy, surgery, IVF

Two types of growth of insects.

Complete metamorphosis and incomplete metamorphosis

List all the phase in growth curve of cells.

Lag phase, exponential phase, stationary phase, maturation phase, senescence phase, death phase.

explain how ecdysis works.

When the insects form a new exoskeleton under the old exoskeleton, the insect will suck air into its body to expand its size. The old exoskeleton is broken. The insect will expand one more time before the new exoskeleton hardens.