Human repro part2

Reproduction in Humans

PART 2

Ante-natal care and birth

• Ante-natal = before birth

• Mother must take care of her health.

Diet with plenty of calcium – for fetus bone development

iron – for the extra blood to help carry oxygen to placenta

carbohydrates – extra energy needed to carry heavier load

protein – help the fetus grow new cells.

Gentle exercise, or special exercises to help during birth


• Useful substances can diffuse across the placenta to the fetus

Nutrients, oxygen, CO2, etc

• Also harmful substances can pass across: - nicotine and carbon monoxide

(Baby can grow more slowly, so is born smaller)

alcohol

drugs

Viruses

(Rubella – can causes baby to be born deaf or other disabilities)


Caring for the newborn baby

To feed the baby, glands in the mother's breasts produce milk (lactation) verb: to lactate

*This is a feature shared by all mammals*

Why is the mother's milk important?

It contains nutrients to help the baby grow

It contains antibodies which help the baby avoid infection



Baby needs to be kept warm: large surface area means the baby loses heat quicker than an adult

Baby needs physical contact

Humans have a very long "childhood" in relation to other mammals. Human children are taken care of until teenaged



Bottle-feeding vs Breast-feeding

Bottle-feeding is more convenient. Other people can help in the task of feeding

Helps the father to bond with the baby.

But

Formula milk is expensive (breast milk is free). Bottle must be sterilised well to avoid bacteria.

Breast milk contains antibodies. Helps bonding between mother/baby.

The composition of the breast milk changes to match the growing babies needs.

Questions

What is implantation?

1. When the egg and the sperm meet to form a zygote

2. When the embryo sinks into the uterus lining

3. When the mature egg is released from the ovary

How is the placenta connected to the fetus?

1. By the umbilical cord

2. By the fallopian tube

3. By the villi

Questions

What is a fetus?

1. The initial stage when the female and male gametes fuse

2. The middle stage before 11 weeks

3. The final stage after 11 weeks

Which is harmful if passed from the mother's blood into the fetus?

1. Oxygen

2. Carbon monoxide

3. Iron

The menstrual cycle

• Hormones#

• Puberty begins during adolescence

• Primary sexual characteristics are boys start to produce sperm and girls start to ovulate

• Secondary sexual characteristics are:

boys develop facial hair/pubic hair, voice breaks, muscular development

girls develop pubic hair, breasts begin to grow, pelvic girdle becomes wider

The menstrual cycle

• Hormones#

These changes happen because of hormones

TESTOSTERONE in males (produced in the testes)

OESTROGEN in females (produced in the ovaries)

*puberty usually begins earlier in girls than boys*

The menstrual cycle

• Menstruation = the loss of the uterus lining through the vagina (a period)

• Menstruation usually lasts 5 days. Then the lining begins to build up again ready for next ovulation

Egg is released into oviduct every month

Uterus lining becomes thick and

spongy

If egg is not fertilised, it dies by the time it reaches

the uterus

It does not sink into the spongy uterus lining (corpus

luteum)

Leaves through the vagina.Spongy lining disintegrates,

passing through the vagina too

The menstrual cycle

• Menstrual Cycle

• Several hormones control this cycle – for example, they are involved in controlling the release of an egg each month from an ovary, and changing the thickness of the uterus lining.

The menstrual cycle

• Menstrual CycleHormone Produced Role

FSH (follicle stimulating hormone) Pituitary gland Causes an egg to mature in an ovary. Stimulates the ovaries to release oestrogen

Oestrogen Ovaries Stops FSH being produced (so that only one egg matures in a cycle). Repairs and thickens the uterus lining. Stimulates the pituitary gland to release LH.

LH (luteinising hormone) Pituitary gland Triggers ovulation (the release of a mature egg)

Progesterone Ovaries Maintains the lining of the uterus during the middle part of the menstrual cycle and during pregnancy.

The menstrual cycle

The menstrual cycle

• Menstrual Cycle

• If a woman becomes pregnant, the placenta produces progesterone. This maintains the lining of the uterus during pregnancy and means that menstruation does not happen.

http://www.bbc.co.uk/education/guides/z7mbkqt/revision/3#glossary-z83wpv4

Methods of birth control

• Birth control helps women to plan when and how many children they want. Also if they want to have children at all.

• Prevent unwanted pregnancies

• Natural methods: Abstinence (avoiding sexual intercourse)

• Timing sexual intercourse when there is no egg in the oviduct

• [Recording body temperature can help, because body temp.

slightly rises around ovulation]


• Chemical methods: Spermicides can kill sperm as it enters the vagina

• Contraceptive pill, stops eggs from being produced

• Contraceptive hormone injection

• Intra-uterine device – placed inside the uterus (by a doctor)

[slowly releases hormones which prevent implantation]


• Mechanical methods: Barrier between sperm and egg

• Condom

• Diaphragm


• Surgical methods: Semi-Permanent (can be reversed)

• Vasectomy for men (local anesthetic) sperm ducts are cut

• Female sterilisation (general anesthetic) oviducts are cut


• Increasing fertility

• Maybe the man isn't producing healthy sperm. Sperm donor. Artificial insemination.

• Problems?

• Maybe the woman isn't producing enough eggs. Fertility drugs (FSH).

• In vitro fertilisation (IVF) – the woman's egg is removed and the man's sperm is added in a petri dish (expensive, and often must be repeated)

Some sexually transmitted infections

• STI / STD(Sexually transmitted disease) / VD (venereal disease)

• Bacterias or viruses passed from one person to another during sexual intercourse

• AIDs (Acquired immune deficiency) – caused by HIV (human immunodeficiency virus)

• T cells (lymphocytes) are destroyed. Without T cells, a person's immune system is unable to fight infections

• Overtime, HIV will develop into AIDs unless treatment is taken

*people who actually die from AIDs usually die from contracting other diseases*

Some sexually transmitted infections

Preventing HIV

The virus cannot live outside the human body

(think the cold virus, is able to pass by sneezing, or can live on surfaces)

*HIV is much more fragile and dies outside the human body*

People can only become infected by: unprotected sexual intercourse.

Blood contact.

People cannot catch HIV by talking/shaking hands/sharing drinks

In fact, the person with AIDs/HIV has more risk, because his/her immune system is reduced

Human repro part2

Education

Transcript of Human repro part2