III: 1 - Reproduction (part 2)

Question 1

Locate and state the function of:

the ovaries

Answer 1

on diagram: Y

The ovaries form, store, mature and release egg cells. They also produce oestrogen.

Question 2

Locate and state the function of:

the oviducts

Answer 2

on diagram: X

The oviducts or Fallopian tubes carry the egg cell/ovum from the ovary to the uterus. They are lined with cilia that help to push/waft the egg cell along (as the egg cell itself is immoblie).

Question 3

Locate and state the function of:

the uterus & the endometrium

Answer 3

on diagram: W

The uterus is the cavity within which the fetus develops. The endometrium is the uterus lining in which the embryo implants itself.

Question 4

Locate and state the function of:

the cervix

Answer 4

on diagram: P

The cervix is a ring of muscle that controls the uterus opening where it joins the vagina.

Question 5

Locate and state the function of:

the vagina

Answer 5

on diagram: R

The vagina is the canal in which sperms are deposited, and is also the birth canal.

Question 6

Locate and state the function of:

the clitoris

Answer 6

on diagram: T

The clitoris is a sensory spot.

Question 7

Locate and state the function of:

the labia

Answer 7

on diagram: S

The labia is a flap that cover the female openings for protection.

Question 8

State the name of these parts on the diagram:

• AA
• U
• Q
• O

Answer 8

• AA: urethra
• U: front of pelvic girdle
• Q: anus
• O: rectum

Question 9

Locate and state the function of:

the testes

Answer 9

on diagram: I

The testes produces and stores sperm, and produces testosterone.

Question 10

Locate and state the function of:

the scrotum

Answer 10

on diagram: H

The scrotum is a sac that protects a testis.

Question 11

Locate and state the function of:

the epididymis

Answer 11

on diagram: J

The epididymis is a coiled structure that stores and matures sperms in males. All the sperm-producing tubes in the testis join to form ducts leading to the epididymis.

Question 12

Locate and state the function of:

the sperm ducts (vas deferens)

Answer 12

on diagram: K

Two muscular tubes, each connected to a testis. They carry the sperms from the testis to the urethra.

Question 13

Locate and state the function of:

the seminal vesicle

Answer 13

on diagram: B

Like the prostate gland, it secretes nutritive fluids for sperms to feed from and swim in, forming semen

Question 14

Locate and state the function of:

the prostrate

Answer 14

on diagram: M

Like the seminal vesicle, it secretes a nutritive fluid to the sperms to form a mixture called semen

Question 15

Locate and state the function of:

the penis

Answer 15

on diagram: F

The male sex organ which ejaculates semen into the vagina during sexual intercourse

Question 16

Compare human male and female gametes in terms of size, numbers, mobility and sex chromosomes

Answer 16

Sperm:

• very small (about 0.01 mm)
• approximately 5 million are released at once
• can move fast due to having a tail/flagella as well as being streamlined
• sex chromosomes can be X or Y

Egg cell:

• larger than sperm, about 0.1 mm
• usually only one released at a time
• cannot move on its own; is moved along by cilia in oviduct
• sex chromosomes are always X

Question 17

What four hormones affect the menstrual cycle?

Answer 17

• Oestrogen
• Progesterone
• Follicle-stimulating hormone (FSH)
• Luteinising hormone (LH)

Question 18

What is the role of FSH (follicle stimulating hormone) in females?

Answer 18

• secreted by the pituitary gland
• causes an egg to mature in an ovary
• stimulates the ovaries to release the hormone oestrogen

Question 19

What is the role of oestrogen in females?

Answer 19

• Produced in the ovaries
• Gives females their secondary sexual characteristics
• Stimulates the repair and build up of the endometrium
• Prepares the uterus for implantation
• Stimulates the release of LH
• Inhibits the release of FSH, so only one ovum matures in a cycle
• Causes change in the cervical mucus

Question 20

What is the role of LH (luteinising hormone) in females?

Answer 20

• produced in the pituitary gland
• signals the ovary to release a mature egg from the Graafian follicle

Question 21

What is the role of progesterone in females?

Answer 21

• produced by the corpus luteum after ovulation
• helps to maintain the uterus lining
• during pregnancy, progesterone is produced by the placenta

Question 22

Describe days 1 to 15 of the menstrual cycle in terms of the changes in the ovaries and uterus.

Answer 22

Day 1 to 5:

• In the ovary, FSH secreted by the pituitary gland to stimulate the maturation of one follicle in the ovary.
• In the uterus: the endometrium breaks down; this is called menstruation

Day 5 to 12:

• The follicle keeps maturing in the ovary
• In the uterus, oestrogen is secreted by the follicle and the ovarian tissues to prepare the endometrium for implantation

Day 13/14/15:

• In the ovary, LH secreted by the pituitary gland to triggers the release of the egg from the Graffian follicle into the fallopian tube

Question 23

Describe days 15 to 28 of the menstrual cycle in terms of the changes in the ovaries and uterus.

Answer 23

Day 15 to 28:

• In the ovary, LH triggers the formation of the corpus luteum
• In the uterus: progesterone is secreted by corpus luteum to keep the endometrium thick, waiting for possible embryo implant.

Day 28 – Scenario 1: Egg not fertilized

• No implantation takes place; the corpus luteum degenerates, causing a lack of progesterone.
• This causes the endometrium to break down - menstruation again, back to day 1

Day 28 – Scenario 2: Egg is fertilized

• Implantation occurs.
• This makes the hormones to keep the corpus luteum maintained, meaning progesterone is kept high.
• This keeps the endometrium thick for pregnancy.

Question 24

How is the egg cell transported from the ovary to the uterus after ovulation?

Answer 24

The movement of the cilia in the oviducts push the egg cell along to the uterus.

Question 25

Describe fertilisation (in humans)

Answer 25

Fertilisation is when the nucleus of a sperm cell fuses with the nucleus of the ovum/egg cell to form a zygote with a diploid nucleus. * One sperm penetrates * The ovum membrane alters to form a barrier against other sperm * Head of sperm (male nucleus) approaches and then fuses with the nucleus of the ovum. This happens in the fallopian tube/oviduct of the female.

Question 26

Outline the early development of the zygote and the development of the fetus

Answer 26

* Zygote divides over and over, to make a ball of cells called an embryo. * *Implantation* occurs when the embryo buries itself in the uterus wall (endometrium) * The embryo produces the placenta, which attaches to the endometrium with finger-like projections * The embryo is attached to the placenta by the umbilical cord * The embryo is changed through growth (*mitosis*) and development (organization of cells into tissues and organs) * After 11 weeks the embryo is considered a fetus

Question 27

What are the functions of the amniotic sac and fluid?

Answer 27

* protects fetus against infection * prevents drying out * prevents mechanical injury by cushioning the fetus against impact * keeps temperature constant * keeps fetus buoyant

Question 28

What are the functions of the placenta?

Answer 28

* produces progesterone to maintain thickness of endometrium * allows substances to diffuse from the blood of the fetus to the mother and vice versa

Question 29

What are the chorionic villi?

Answer 29

The chorionic villi are finger-like projections grown into the uterus wall from the placenta in order to give maximum surface area for diffusion.

Question 30

What is the function of the umbilical artery?

Answer 30

The umbilical artery carries blood away from the fetus to the placenta, containing waste materials such as carbon dioxide, and nitrogenous wastes like urea.

Question 31

What is the function of the umbilical vein?

Answer 31

The umbilical vein carries blood towards the fetus from the placenta containing nutrients such as glucose, amino acids, fatty acids and glycerol, antibodies, hormones and oxygen. It may also carry unhealthy substances such as drugs and alcohol, if the mother takes them.

Question 32

Why must the blood of the mother and fetus never mix?

Answer 32

The mother and fetus may have different blood types, and their mixing would be fatal to both of them as it will result in clotting.

Question 33

How do subtances from the mother's blood reach the fetus's blood (and vice versa)?

Answer 33

Subtances will diffuse across from the mother's blood to the fetus' blood (and vice versa) within the placenta.

Question 34

Describe the ante-natal care of pregnant women

Answer 34

* Change in diet: * More proteins → growth of fetus * Slightly more fat → the new cells’ cell membrane * More vitamin C and D → blood vessel walls and bones * Iron → haemoglobin * Calcium → growth of bones and teeth * Folic acid → development of spine * Guidance on motherhood * Checks on fetus and mother including: weight check, blood tests, urine tests, blood pressure checks, ultrasound scanning etc. * Generally maintaining good health

Question 35

Why must a pregnant women eat more green, leafy vegetables?

Answer 35

Green, leafy vegetables contain folic acid, which is important for the development of the fetus's spine. A deficiency in folic acid can result in spina bofida.

Question 36

What are the 5 main events of labour (parturition)?

Answer 36

1. Uterine wall contracts and pushes fetus 2. Cervix widens 3. Amnion breaks and fluid escapes 4. Head of fetus emerges 5. Umbilical cord is cut 6. Afterbirth - placenta is pushed out

Question 37

What is the difference between fraternal and identical twins?

Answer 37

Fraternal twins are formed from two different ova and are non-identical. Identical twins are formed when a single zygote splits into two and forms two embryos with the same genetic material.

Question 38

What are the advantages of breast feeding?

Answer 38

* milk contains high level of nutrients * milk is easily digested * milk contains antibodies * contents of milk vary to meet the changing nutritional requirements of the baby * milk is always at the correct temperature * no preparation time * free * decreases baby's risk of obesity and SIDS * bonding time between mother and baby

Question 39

What are the disadvantages of breast feeding?

Answer 39

* mother must be available * may cause pain or discomfort to mother * harmful substances from mother get passed on to baby * no way of telling how much baby is consuming

Question 40

What are the advantages of bottle feeding?

Answer 40

* anyone can feed the baby * prevents transmission of disease from mother * can measure how much baby is drinking

Question 41

What are the disadvantages of bottle feeding?

Answer 41

* preparation time for formula milk * expensive * baby may not tolerate formula * must carry equipment for bottle feeding

Question 42

Describe the role of testosterone in the development and regulation of secondary sexual characteristics at puberty

Answer 42

The testes start to produce sperm and release testosterone into the bloodstream, giving males their secondary sexual characteristics: * Enlargement of testes and penis * Voice deepens * Hair: pubic region, armpits, chest, face

Question 43

Describe the role of oestrogen in the development and regulation of secondary sexual characteristics at puberty

Answer 43

At about the same time as the first ovulation, the ovaries begin to release oestrogen into the bloodstream, giving females their secondary sexual characteristics: * Enlarged breasts * Widened hips * Pubic hair * Menstruation starts

Question 44

What different methods of birth control are there?

Answer 44

* natural (abstinence, rhythm method) * chemical (contraceptive pill, spermicide) * mechanical (condom, diaphragm, femidom, IUD) * surgical (vasectomy, tubectomy)

Question 45

Describe artificial insemination (AI), and list its social implications

Answer 45

* Male infertility - caused by low sperm count of sperms which are insufficiently mobile * Sperm donor - another man who donates his sperm to fertilise the women's eggs * Semen is injected through a tube into the top of the uterus * * * * Religious/moral objections * Child may never know biological father * Legal problems about the legitimacy of the child in some countries

Question 46

Describe in vitro fertilisation (IVF) and list its social implications

Answer 46

* the woman is first given fertility drugs (containing FSH and LH) to make her produce a lot of eggs * eggs are then taken out of the woman and replaced in a sterile dish, and the man’s sperms added * a fertilised egg is chosen and put back in the woman’s uterus * * * * unwanted embryos are destroyed * couples can choose embryos with 'desirable' qualities and destroy the rest * religious objections

Question 47

Describe the use of fertility drugs and list the social implications

Answer 47

* drugs contain FSH to stimulate eggs to mature and LH to stimulate ovulation * administration of the drug is timed to promote ovulation to coincide with copulation * * * * may result in multiple conceptions * too many devloping fetuses may stunt growth

Question 48

Gonorrhoea: ## Footnote Signs & Symptoms: ? Effects: ? Treatment: ? Prevention: ?

Answer 48

Signs & Symptoms: (males) Yellow, pus filled discharge from the urethra, burning sensation during urination, painful and swollen testes. (females) Vaginal discharge but no pain. Effects: Bacteria reproduction in the urethra (males) or cervix (females). First signs occur within 5-7 days. If left untreated, the disease can travel through reproductive tract, causing sterility. Treatment: antibiotics Prevention: Abstain from sexual intercourse, have only one sexual partner, use condom, trace, warn and treat sexual partners with the disease to stop it from spreading.

Question 49

HIV (human immunodeficiency virus) ## Footnote Transmission: ? Effect on immune system: ?

Answer 49

Transmission: direct contact of body fluids, sexual intercourse Effect on immune system: attacks lymphocytes, weakening the immune system * virus infects lymphocytes (white blood cells) * attacks T-cells and uses them to make copies of itself * destroys T-cells so immune system is not strong/nonfunctional * virus mutates to mask itself * about 10 years later, the patient develops AIDS