TOPIC 1: LIFESTYLE,
HEALTH AND RISK
TRANSPORT OF SUBSTANCES, WATER, BLOOD VESSELS, HEART
AND CARDIAC CYCLE, ATHEROSCLEROSIS, BLOOD CLOTTING,
ENERGY BALANCE, CARBOHYDRATES, LIPIDS, HIGH AND LOW
DENSITY LIPOPROTEINS, TREATMENT OF CVD
, TRANSPORT OF SUBSTANCES
• In order to survive, animals require essential substances to enter and
leave the body in sufficient quantities and be transported around the
body. The needs of small organisms can be served through diffusion
due to large SA:vol ratio of the body. However, as the size of the
organism increases:
Surface area to vol ratio decreases
Diffusion distance increases
Metabolic rate increases
, • Diffusion becomes insufficient for more complex organisms. Larger
organisms have a mass transport system, consisting of the heart
and circulation which moves the substances around the body and
allows exchange of substances to take place.
Features of a mass transport system:
• A network to move through e.g. vessels.
• A medium for movement a fluid like blood.
• Controlled direction- to move substances to/from where they are
needed e.g. blood is moved along a pressure gradient created by the
heart, the direction of flow is controlled by valves.
• Maintenance of speed, e.g. contraction of the heart and elastic recoil
of arteries helps to maintain the pressure gradient, thus speed.
HEALTH AND RISK
TRANSPORT OF SUBSTANCES, WATER, BLOOD VESSELS, HEART
AND CARDIAC CYCLE, ATHEROSCLEROSIS, BLOOD CLOTTING,
ENERGY BALANCE, CARBOHYDRATES, LIPIDS, HIGH AND LOW
DENSITY LIPOPROTEINS, TREATMENT OF CVD
, TRANSPORT OF SUBSTANCES
• In order to survive, animals require essential substances to enter and
leave the body in sufficient quantities and be transported around the
body. The needs of small organisms can be served through diffusion
due to large SA:vol ratio of the body. However, as the size of the
organism increases:
Surface area to vol ratio decreases
Diffusion distance increases
Metabolic rate increases
, • Diffusion becomes insufficient for more complex organisms. Larger
organisms have a mass transport system, consisting of the heart
and circulation which moves the substances around the body and
allows exchange of substances to take place.
Features of a mass transport system:
• A network to move through e.g. vessels.
• A medium for movement a fluid like blood.
• Controlled direction- to move substances to/from where they are
needed e.g. blood is moved along a pressure gradient created by the
heart, the direction of flow is controlled by valves.
• Maintenance of speed, e.g. contraction of the heart and elastic recoil
of arteries helps to maintain the pressure gradient, thus speed.
