human reproduction

what are somatic cells and sex cells

any cells that form part of the organism’s body except gametes, having diploid number of chromosomes

are cells that is involved in reproduction containing haploid number of chromosomes

what are the chromosomes number in a fruit fly and a human

8 chromosomes and 46 chromosomes

function of testes

1. gonads of male

2. produces sparks and male sex hormones, testosterone

function of sperm duct / vas deferent

1. transport sperms from testis to urethra

function of scrotum

1. skin punch containing and protecting testis

Function of epididymis

temporary storage for sperms, and the place where they mature

Function of p3nis

organ for introducing sperm into the female reproductive tract

function of urethra

A tube that carries both urine and semen along p3nis to be released from the body

function of prostate glands, seminal vesicles and cowper’s gland

secretes seminal fluids, containing fructose and zinc to nourish the sperms (Seminal fluid + sperms = semen)

function of ovary

• gonads of female

• Produces ova and female sex hormones (estrogen & progesterone)

function of oviduct / fallopian tube

1. Transfer ova from ovary to uterus

2. Lined with ciliated epithelial cells

3. Muscular walls contracts, helping to move ovum towards uterus

4. Also site of fertilisation

fucntion of uterus

1. Receives , nourishes and protects fetus during pregnancy

2. Muscles contract during labour pains to expel baby during birth

Function of cervix

place where vagina meets the owner portion of uterus, helping to keep baby in the uterus until it is ready to be born

function of vagina

• opening for entry of p3nis during copulation / s3xual intercourse

• acts as a birth canal at the end of pregnancy

Similarities between ovumand sperm

• same chromosome number, 23

differences between ovum and sperm

1. Size

   1. Ovumis larger than sperm (120nm vs 2.5nm)

2. Shape

   1. Round with outer protein coat

   2. 3 parts — head, middle piece, tail

3. Nucleus and cytoplasm

   1. Large nucleus, abundant of cytoplasm containing small amounts of yolk

   2. Large nucleus, small amount of cytoplasm

what the yolk in the ovum do?

• nourishment for developing embryo

Define puberty

• time of sexual maturation in humans, when a person changes from a child to an adult

What changes happen during puberty

1. Reproductve system becomes mature

2. Surge in sex hormones

3. Production of mature ovum and sperms

4. Development of secondary sexual characteristics

describe the cycle of menstruation

1. Begins with the monthly discharge o blood due to breakdown of endometrium

2. Uterine lining thicken with rich network of blood vessels, preparing uterus to receive embryo if there is successful implantation

3. 14 days after menstruation → ovulation, where ovum is released from the ovary. Uterine lining continues to thicken due to increasing P levels (and E)

4. If there’s fertilisation

   1. Sperm nucleus and ovum nucleus fuse together to form a zygote / fertilised egg cell, develops into blastocyst, then to embryo

   2. Embryo burrow into uterine lining

   3. Uterine thickness is maintained by progesterone

5. If no fertilisation

   1. Progesterone and oestrogen drops

   2. Uterine lining breaks down

   3. Blood, damaged blood vessels and disintegrated ovum discharge through the cervix and vagina as menstrual blood

when is the fertile period in a menses cycle

day 10/11 to 17

what does each of the 4 hormones do in the menstrual cycle

1. Oestrogen

   1. stimulates the repair and thickening of uterine lining

   2. inhibit FSH and LH for most of the cycle

   3. stimulates FSh and LH release pre-ovulation

2. Progesterone

   1. Thickening of uterine lining

   2. inhibits FSH and LH

3. FSH

   1. Stimulates follicle growth and estrogen secretion

4. LH

   1. Surge in LH triggers ovulation

what hormones does the developing follicles and the corpus luteum secrete

1. developing follicles → E2 only

2. corpus luteum → P and some E2

what causes menstruation

1. corpus luteum breakdown

2. leading to low levels of E2 and P

what happens to the P level in a pregnant woman

1. P continues to be secreted by corpus luteum which do not break down

2. corpus luteum persist until placenta is formed to take over P production which continues to increase throughout pregnancy

what happens to umbilical cord after birth

1. cut and clamped

2. part attached to mom is discharged together with the placenta

3. remaining of umbilical cord attached to the newborn will shrivel and fall off

changes in a follicle during menstrual cycle

• ovaries contain many developing follicles

• Primary follicles consisting of follicle cells and potential egg

• primary follicle develop into mature Graafian follicle

• developing follicles secrete estrogen

Day 14

• Graafian follicle rupture and releases egg into oviduct (ovulation)

• immediately during ovulation, follicle is ruptured so no E2 is produced in the ovaries so E2 levels drop

• after ovulation, Graafian follicle develops into corpus luteum, which produces hormones to prepare body for pregnancy (P and some E2)

• if no fertilisation, corpus luteum will persist for sometime then breakdown, causing E2 and P levels to fall and menstruation occurs

hormonal cycle in menses

Day 1-5

• pituitary gland secretes FSH into the bloodstream

Day 6-13

• FSH stimulates development of primary follicles to form mature follicle

• FSH stimulates follicles in ovaries to release oestrogen

• Oestrogen stimulates repair and growth of endometrium so that it becomes thick and spongy with blood vessels

• High oestrogen in blood inhibits FSH release, preventing the ripening and growth of more follicles

Day 14

• LH surge causes ovulation, and formation of corpus luteum (CL secretes progesterone and oestrogen)

Day 15-28

• further thickening of U. Lining w BVs in preparation for fertilised egg

• Progesterone inhibits ovulation and FSH production

define fertilisation

the fusion of ovum nucleus and sperm nucleus forming a zygote

Usually occurs in the fallopian tube

fertilisation process

1. Head of sperm release enzyme in special vacuole / acrosome

2. Enzymes digest the outer protein of ovum. Sperm head penetrate the ovum, and the cell membrane of the sperm fuses with the cell membrane of ovum

3. Outer protein coat thickens, forming a barrier to prevent entry of other sperms. The rest of the sperms die. the special sperm’s tail and middle piece will be detaches

4. Sperm nucleus fuse wth ovum nucleus, forming a zygote

how many umbilical arteries and veins are there

1 umbilical vein, 2 umbilical artery

Which directions do umbilical arteries and veins carry blood in?

• umbilical artery carry blood away from the feotus heart, carrying deoxygenated blood and nitrogenous waste and urea

• Umbilical veins carry oxygenated blood and nutrients towards feotus heart

umbilical function

1. Attaches feotus to placenta, containing blood vessels which transports dissolved gases, waste, food etc to and from the placenta

amnion structure and function

structure

-membrane that surrounds whole embryo /feotus

-made out of amniotic membrane

Unction

-secretes amniotic fluid

function of amniotic fluid

1. Protects and cushions embryo from physical damage and absorbs shock

2. Keep even pressure all around t, allowing organs to develop without restriction

3. Allows feotus to move freely during growth

4. Lubricates and reduces friction in vagina during birth

Digestive function of placenta

allows for the exchange of digested food from maternal blood to fetal blood, such as glucose and amino acids

Since feotus cannot digest food

Respiratory Function of placenta

allows for exchange of oxygen from maternal blood to fetal blood

Allows for exchange of carbon dioxide from fetal blood to maternal blood

Since fetus cannot GE as lungs are not mature

excretory functions

1. Allows for exchange of metabolic aste fro fetal blood to maternal blood, such as urea, carbon dioxide and excess water

Hormonal function for placenta

produce progesterone to continue thickening of uterine lining because the ovaries cannot secrete enough progesterone, and maintain embryo in uterus

(Soplacenta is an endocrine gland)

adaptation of placenta

1. Blood spaces filled with mother’s blood

2. Villi grows into the uterus wall, increasing surface area for diffusion

why can’t mother and chil’ds blood mix

1. Blood groups may be different — mixing o blood may lead to agglutination and the issues that follows

2. If BP changes in mother, BP in fetus will change. any spikes in BP will damage the delicate BVs in the fetus

Why maternaland fetus bloodstreams are in close proximity

increase the rate of diffusion for nutrients gases and waste