male reproductive system

1. the testes [pair of oval glands lying outside the abdominal cavity enclosed in the scrotum]- produces sperms & hormones

• why do the testes decend into scrotum prior to birth?

1. seminiferous tubules [three tightly coiled tubules lie in each lobule of the testes]- produces sperms by spermatogenesis interstitial tissue [between seminiferous tubules, in the testes]- they secrete testosterone
2. epididymis [comma shaped organ which fits like a cap on the testes and continues as the vas deferens] - site of sperm maturation and storage.
3. vas deferens [it moves along behind the border of the testes and goes into the inguinal canal]- transports sperms from epididymis to the urethra.
4. ejaculatory duct [behind the urinary bladder]- eject the sperms into the urethra.
5. seminal vesicle [lie behind and at the base of the urinary bladder infront of the rectum]- provides the energy source to the sperms & neutralises the acidic environment of the vagina.
6. prostate gland [circles the urethra at the base of the urinary bladder]- secretions contribute to sperm motility and viability.
7. cowper’s gland [located beneath the prostate gland]- lubricates the penis during sexual intercourse.
8. penis- semen from the urethra is expelled.

sperm

• acrosome- breaks the membrane of the ovum
• abundant mitochondria allows for locomotion

female reproductive system

1. ovaries [upper pelvic cavity, one on either side of the uterus]- produce mature ova by oogenesis, discharge mature ova by ovulation, secrete oestrogen, progesterone and relaxin.
2. fallopian tubes [extend laterally on each side of the uterus, open ends are called infundibulum]- transports the ovum from the ovary to the uterus.
3. uterus [between the urinary bladder and the rectum]- protects and nourishes the developing embryo, cervical mucous provides the energy requirements of the sperms.
4. vagina [extents from the uterus, between the urinary bladder and the rectum]- receives the penis, pathway for menstrual flow, parturition.
5. vulva- visible part of the vagina.

ovulation

it is the release of the mature ovum into the pelvic cavity by the rupture of the graafian follicle.

as the ova matures, it gets filled with fluid. the surrounding nutritive tissue is called the graafian follicle. when the graafian follicle is ripe it pokes out from the ovary. the remnants of the graafian follicle forms the corpus luteum which secretes the hormones progestrone, relaxin and oestrogen

fertilization

it is the union of two gametes to form a zygote.

the site of fertlization is the fallopian tube

identical twins

they are formed when one fertilized egg splits into two. each part develops into separate indivsuals but share the same placenta.

fraternal twins

when two different eggs are fertilized at the same time but by two different sperms. they have separate placenta’s.

the attachment of the blastocyst to the endometrium 7-8 days after fertilization is called implantation

the total period of intrauterine foetal development [nine months] is termed as the gestation period

placenta

it is a vascular structure which develops in mammal females which forms an association between the mother and the foetal tissue.

the tough umbilical chord serves as a blood vascular connection between the foetus and the uterine wall

• the amniotic fluid protects the embryo from any mechanical jerks. it also prevents the embryo from sticking to the uterus wall.
• the mothers blood does not circulate in the foetus,
• what is the function of the placenta?
• the artery in the placenta carries deoxygenated blood away from the embryo’s heart.
• oxytocin- induces contractions
• prolactin- stimulates the production of breast milk

the menstrual cycle

| FSH | anterior pituitary | - stimulates follicle growth

• stimulates oestrogen | causes an egg to mature in the ovary | | --- | --- | --- | --- | | oestrogen | ovaries [developing follicle] | - development of endometrium
• stimulates LH
• inhibits FSH & LH | repairs and thickens the endometrium | | LH | anterior pituitary | - causes ovulation
• corpus luteum
• progestrone stimulation | triggers ovulation | | progestrone | ovaries [corpus luteum] | -thickening of endometrium
• inhibits FSH & LH | maintains ligning of endometrium |

phases

1. mestrual phase- periodic discharge of blood caused due to the sudden reduction of hormone level.
2. follicular phase - ova matures into the graafian follicle. the lining in the endometrium starts to build up. oestrogen production is increased.
3. ovulation- it is the rupture of the graafian follicle. oestrogen is further increased prior to ovulation. after this the corpus luteum is formed which secreted progestrone & oestrogen.
4. luteal phase- progestrone. prepares endometrium for the embryo. if it does not get implanted then another menstrual cycle commences.