Hormones

Homeostasis is the process by which the interval enviroment inside our bodies is kept constant. This process involves your nervous system,your hormones and body organs.

Controlling water and ions:

take in water and minerals when you eat and drink.Lose water when you breath out and in your sweat. The kidneys control the balance of water and mineral ions in your body. If too much water moves in and out of your cells, they get damaged.

Controlling temperture:

The normal body temperature is 37*c, at only a few degrees above or below normal temperature, the reactions in your cells stop and die. The skin controls the temperature by sweating to cool you down and shivering to warm you up.

Controlling blood sugar:

Take in sugar when you eat and drink.to much sugar can damage body cells. sugar is kept constant by hormones made in the pancreas

• Endocine glands make and release hormones into the body
• what are hormones?
  • hormones are chemical messages which control many of the processes going on inside out bodies
• hormones are carried around the body to target organs in the blood stream

• Sex and growth hormones-pituitary
• thyroxide-thyroid
• insulin and glucagon-pancreas
• adrenaline-adrenal
• oestrogen-overies

The changes in the menstural cycle invloves the build up of the lining of the uterus to coincide with the release of an egg(ovulation) so as to provide an enviroment to accept a fertilised egg. this is followed by the breakdown of this tissue, the egg is not fertilised. This is called menstuation. Hormones of the pituitary gland and the ovaries control the mentrual cycle

FSH-causes egg tomature in ovaries

LH-cause the released of a matured egg

Oestrogen:

where is it made? overies

FHS

where is it made? overies

LH

where is it made? overies

Why is it needed? needed when a womanis not producing eggsorthe eggs are not maturing

Hormones it contains:FHS and LH

How does it work?FHS cause the egs to mature in the overies and triggers egg production. LH causes matured egg to be relased.

Advantages:

• Enables infertile women to have babies

Disadvantage:

• can lead to multiple births and can be expensive

Why is it needed? Needed when a woman want to have control over when to get pregnant

Hormones it contain: Oestrogen and Progesterones

How does it work? Oestrogen stops FSH production,so no eggs are maturing and are released

Advantage:

• Effective in controlling conception

Disadvantage:

• must be taken regulary. can produceside effects such as putting on weight

APlant hormones are called auxin. They are made at the tip of shoots. Auxins stimulate the shoots to grow, and causes cellsto elongate. Plants respond to light,moisture and gravity. plant responses are called tropisms.

Phototropism:

A plants response to light is called phototropism. is a plant shoot gets light from one side only, the auxin will build up on the shaded side on the stem. this causes more growth on the shaded side. As a result, the plant will grow towards the light.This is called positive phototropism.

Geotropism:

A plants response to gravityis called gravitropism. Shoots grow up away from gravity, and roots grow down toward gravity. Auxins collect on the lower side of the shoots and roots. This stimulates the growth of cells on this side in shoots, but slows down grown in roots. As a result, shoots grow upwards away from gravity.This is called Positive geotropism.Roots grow downwards toward gravity.This is called negative geotropism.

Growers often use plant hormones to make plants grow and develop in ways that they want. Gardeners often grow new plants from cuttings. They usually dip the base of the cuttings into a powder or gel called rooting hormone. This contains a plant hormone that makes the cutting grow roots

plant hormones are also used as weedkillers.The hormone make the weeds grown fastand then die. The hormones do not effect the grass because grass has a different metabolism to the weeds.