Biology LC - Human Reproduction 2

What is meant by infertility?

The inability to produce offspring

What is the approximate survival time of sperm in the female tract

0-7 days

Female Infertility

Infertility is the inability to conceive.

Most commonly due to failure to ovulate due to a hormonal disorder

Fibroids

Benign tumors of the uterus

Symptoms: larger fibroids can cause heavy and prolonged menstrual bleeding, pain, miscarriage or infertility.

cause: abnormal responses to oestrogen

Prevention: Regular exercise

Treatment: removal by surgery

Name two structures that are formed in the days following fertilisation up to the point of implantation

• morula

• blastocyst

Give two roles of placenta

• supplies nutrients from mother to embryo

• gas exchange

• production of hormones

• the removal of waste

• prevents the entry of certain pathogens

Give an outline description of the birth process, include the role of hormones

• Placenta stops producing progesterone → uterus contracts

• Foetus pushed toward cervix → blood & amniotic fluid expelled

• Foetus exits cervix & vagina (usually head first)

• Uterus contracts → placenta & membranes expelled

Name two tissues involved in the formation of the placenta

1. Embryonic tissue

2. Endometrium

Describe the differences between the male and female gametes using the following headings

1. Relative numbers of each produced

2. Frequency of gametes produced

3. Relative size

1. Relative numbers of each produced: Low in females, high in males

2. Frequency of gametes produced: from puberty until menopause in females, continuously in males

3. Relative size: Large in females, Small in males

Name the structure that the Graafian follicle turns into on day 14 of the menstrual cycle

Corpus Luteum

Contraception can include natural, mechanical and chemical methods.

Give one of each type of method

Natural: Withdrawal

Mechanical: Condom

Chemical: The Pill

What is meant by the tern implantation?

Embedding of the fertilised egg into the lining of the uterus (endometrium)

Name, in the correct order, the developmental stages from the fertilised egg to implantation

1. Morula

2. Blastocyst

Outline what happens to each of the following after implantation has taken place

1. The level of the hormone progesterone in the blood

2. The endometrium

1. progesterone level increases

2. Endometrium thickens

Embryo cells organise themselves into three germ layers

name these three germ layers

1. Ectoderm

2. Mesoderm

3. Endoderm

Explain the term in vitro fertilisation

The process of fertilising an egg cell with a sperm cell outside of the body

Suggest a reason for the removal of several eggs during IVF

To increase the chances of successful implantation

Identify the germ layer form which the skin of the developing embryo arises

Ectoderm

Give two reasons why the blood of the mother and the blood of the foetus must not mix

• blood groups may be different

• blood pressure of mother’s system could cause damage to the embryo

State the roles of FSH and LH

FSH: stimulates the development of potential eggs

LH: causes ovulation

Mitochondria are inherited exclusively from the mother. Suggest why this is the case

No sperm mitochondria enters the egg

For each germ layer, name a structure in the body that develops from it

Ectoderm - skin

Mesoderm - musculoskeletal system

Endoderm - digestive system

What is the amnion

A membrane surrounding the embryo

What is the importance of the amnion for the foetus?

secretes amniotic fluid and protects the foetus

Explain the following terms:

• Morula

• Blastocyst

• Morula - is a solid ball of cells formed from a zygote by mitosis

• Blastocyst - is a hollow, fluid-filled ball of cells formed from the morula

Give two biological advantages of breastfeeding

• contains ideal balance of nutrients for baby

• supplies antibodies

• may help reduce risk of breast cancer

• safer for baby, less chance of infection

Write notes on the formation of the placenta

• After implantation, the chorion forms around the embryo

• Chorionic villi grow from the chorion into the mother’s endometrium

• These villi connect with the mother’s blood vessels

• Together they form the placenta

• The placenta is fully functional after 3 months