Unit 2: Physiology and Health

Section 8 – Reproductive organs and Hormonal

Control

CfE Higher Human Biology

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Learning Intentions

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I can state that testes produce sperm in the seminiferous tubules and testosterone in the interstitial cells.

I can name the prostate gland and seminal vesicles as the structures which secrete fluid that maintain the mobility and viability of sperm.

I can state that the ovaries contain ova, and that each ovum is surrounded by a follicle that secretes hormones.

I can state that fertilisation occurs when an ovum is fertilised in the oviduct by a sperm, and this forms a zygote.

I can state that the pituitary gland releases follicle stimulating hormone (FSH) and luteinising hormone (LH) or interstitial cell stimulating hormone in males (ICSH) after being stimulated by a releaser hormone produced in the hypothalamus.

I can identify FSH as the hormone that promotes sperm production and ICSH as the hormone that stimulates testosterone production.

I can state that testosterone also stimulates sperm production, as well as activating the prostate gland and seminal vesicles.

I can describe the negative feedback control of testosterone by FSH and ICSH.

I can describe the stages of the menstrual cycle from the first day of menstruation, through ovulation to the endometrium lining breaking down once more.

I can state that FSH causes a follicle to develop in the ovary, and the follicle also produces the hormone oestrogen.

I can state that the follicle develops into the corpus luteum after ovulation, which then produced progesterone and causes the lining of the endometrium to thicken.

I can explain the action of the female hormone oestrogen in the follicular phase and progesterone in the luteal phase of the menstrual cycle.

I can state that the endometrium lining builds up, ready for implantation of a blastocyst due to the action of progesterone

I can state that the cervical mucus changes due to the action of oestrogen to allow the sperm to penetrate more easily.

I can describe the negative feedback control of FSH and LH through the action of the ovarian hormones.

Reproduction Revision

• All living things reproduce and produce offspring similar to themselves.

• If they did not then eventually the species would become extinct.

Sex Cells – Sperm

Sperm are produced in sex organs called testes which also manufacture the male sex hormone testosterone.

In males, the sex cells are called sperm.

headtail middle piece

cell membrane nucleus containing DNA

• Sperm (full name spermatozoa) are formed by meiosis in tubes called seminiferous tubules. These tubules unite to form coiled tubes which connect to the sperm duct.

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Testosterone is produced by interstitial cells located in the tissue between the seminiferous tubules. Testosterone passes directly into the bloodstream. https://www.youtube.com/watch?v=R-lrEBevJ60

Accessory Glands• The seminal vesicles secrete liquid rich in

fructose and prostaglandins. The fructose supplies the sperm with energy and the prostaglandins act as hormone like compounds that help the female reproductive tract to contract which helps the sperm move towards the oviduct.

• The prostate gland secretes a thin liquid containing enzymes which helps with motility.

• Semen is the collective name given to the milky liquid released by the male.

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Sex Cells – Egg

Eggs are produced in sex organs called ovaries by meiosis.

In females, the sex cells are called eggs.

nucleus containing DNA

membrane jelly coat

cytoplasm

• Each egg is contained in a Graafian follicle which secretes the hormone oestrogen. Following ovulation (release of an egg), the Graafian follicle develops into a corpus luteum which secretes the hormone progesterone.

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Sexual Reproduction• This is when 2 types of sex cells or

gametes are produced which then joins together at fertilisation to produce the new individual.

• In animals the gametes are egg and sperm.

An egg is so big that this is how big a sperm looks next to it.

The egg is much larger because it has a food supply.

Fertilisation

Zygote - Sperm enters the egg. The sperm nucleus fuses

with egg nucleus to create a single cell.

Fertilisation http://www.youtube.com/watch?v=vyWuMo3bzRU&feature=relmfu

After fertilisation….

1 cell – fertilised

egg

Cell division2 Cells

4 Cells

8 cells…leading to a ball of cells

Revision. The female reproductive system

Revision: The male reproductive system

Male or female?

Roles of the reproductive system

Fertilisation and implantation

The placentaHow does an embryo receive food and oxygen and how does it get rid of waste?

An embryo forms a structure called the placenta, which attaches to the uterus wall.

The umbilical cord joins the fetus to the placenta.

In the placenta, food and oxygen diffuse from the mother’s blood into the blood of the foetus.

Carbon dioxide and waste products diffuse from the blood of the foetus into the mother’s blood.

umbilicalcord

Summary: Role of the Placenta

1. Nourishment• Food from the mother

2. Gaseous exchange• Oxygen from mother• Carbon Dioxide from embryo to mother

3. Excretion• Waste materials from embryo to mother

Male Reproductive System

Made up of testicles, duct system, accessory glands and penis.Functions:•produce hormones•produce sperm •store sperm•deposits sperm inside vagina during sexual intercourse

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FYI - sperm• The average man

produces roughly 525 billion sperm cells over his lifetime and releases, in one way or another, more than one billion of them per month and anywhere from 40 million to 1.2 billion in a single ejaculation.

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Sperm (spermatozoa) production

•Testosterone produced in interstitial cells stimulates sperm production. Testosterone passes directly into the bloodstream.

•Sperm formed by meiosis in seminiferous tubules.•These tubules unite to form coiled tubes which connect to the SPERM DUCT. (Free swimming sperm leave the testes by this duct.

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Sperm mother cell

Spermatozoa

Interstitial cell

Accessory Glands

• Fertilisation is dependent on;– Motility of sperm

which requires a fluid medium.

– a source of energy• The semen released by

the male during ejaculation contains sperm from the testes and fluid secretions from the seminal vesicles and the prostate gland.

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The Accessory Glands con’t

Seminal vesicles: secrete viscous liquid containing: – Fructose:Provides energy source for motility following there release

after male ejaculation.– Prostaglandins: (Hormone like compounds)Stimulate contraction in the

female reproductive tract. These movements help the sperm reach the oviduct at a much faster rate than could be achieved by swimming alone.

Prostate Gland:– Secretes a thin lubricating fluid containing enzymes which

maintains the fluid medium at OPTIMUM VISCOSITY for sperm motility.