Hormones

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  • Created by: Aabir
  • Created on: 01-04-16 07:15

Anti-diuretic hormone (ADH)

Souce:

Pituitary gland (in the brain)

Role:

Controls water content (osmoregulation)

Effects:

Increases the permeability of the kidney tubules to water

This means that osmoregulation can be maintained because if the hypothalamus section of the brain detects a change in the body's water levels, the pituitary glands will release more or less ADH, allowing more or less reabsorption of water at the collecting ducts according to the body's needs. This process is called negative feedback.

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Adrenaline

Souce:

Adrenal glands (on top of the kidneys)

Role:

Readies the body for a 'fight or flight' response

Effects:

Increases heart rate, blood flow to muscles and blood sugar level

It does this by binding to specific receptors in the heart, causing the cardiac muscle to contract more frequently and with more force, so heart rate increases and the heart pumps more blood. This increases oxygen supply to the tissues, getting the body ready for action.

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Insulin

Souce:

Pancreas

Role:

Helps control the blood sugar level

Effects:

Stimulates the liver to turn glucose into glycogen for storage

If there is too much sugar in the blood, it is detected by the hypothalamus and a signal is sent to the pancreas to release insulin, causing the liver to turn the excess glucose into glycogen. If blood sugar levels are too low, the hypothalamus signals the pancreas to release another hormone, glucagon, which stimulates the liver to break down some glycogen back into glucose.

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Testosterone

Souce:

Testes

Role:

Main male sex hormone

Effects:

Promotes male secondary sexual characteristics, e.g. facial hair

 

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Progesterone

Souce:

Ovaries

Role:

Supports pregnancy

Effects:

Maintains the lining of the uterus

A thick spongy layer full of blood vessels is maintained from around day 14 to day 28 of the menstrual cycle. If no fertilised ovum has landed on the uterus wall by day 28, the level of progesterone falls, the lining breaks down and the cycle starts again. If a fertilised ovum implants in the uterus then the level of progesterone stays high to maintain the lining of the uterus during pregnancy. 

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Oestrogen

Souce:

Ovaries

Role:

Main female sex hormone

Effects:

Controls the menstrual cycle and promotes female secondary sexual characteristics (e.g. widening of the hips)

Oestrogen causes the uterus lining to thicken and grow from days 4 to 14. It then stimulates the production of a hormone called LH which stimulates the release of an ovum on day 14.

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