Biology unit 3 (topics 1,2 + 3)

Transporting materials in humans and plants, and how exercise effects the body.

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  • Created on: 15-05-11 13:12
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Active Transport ­ absorbing a substance against a concentration gradient. Requires
energy produced by respiration. In humans, sugar may be absorbed from the intestine
and the kidney tubules by A.T.
Exchanging Material in Humans
In humans there are organ systems that are specialised to aid the exchange of materials.
Villi in the Small Intestine ­ Villi line the small intestine walls, increase surface area,
extensive network of capillaries­ absorbs products of digestion
by diffusion and active transport.
Alveoli in the Lungs- Efficient at exchanging oxygen and carbon dioxide : large moist
surface area, excellent blood supply. The capillaries are only
one cell thick, allowing blood to pass easily.

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The trachea divides into 2 tubes called bronchi, which divide again several times to form
bronchioles, which divide again and again to end in air sacs called alveoli!
The size of stomata is controlled by guard cells. If plants lose water faster than it is gained
by the root hair cells in the roots, the stomata can close to prevent wilting and dehydration.…read more

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How are dissolved materials transported around the body?
The heart acts as a pump in a double circulation system. Blood flows around the system and
passes through the heart twice on each circuit.
Blood travels AWAY from the heart through arteries and TOWARDS the heart through veins.
In the organs, blood travels through capillaries.
Substances needed by the cells in the body tissue pass out of the blood. Substances
produced by cells pass into the blood through capillary walls.…read more

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right side
Deoxygenated blood from the heart, to the lungs to pick up oxygen, then back to the heart.
How does exercise affect the exchanges within the body?
During exercise:
Heart rate increases
Arteries supplying muscles dilate
Rate and depth of breathing increases
Increased blood flow to muscles
Supply of oxygen and sugar is increased, speeding up the removal of carbon dioxide
Glycogen stored in muscles is broken down to glucose for use in respiration.…read more

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