TRANSPORT IN ANIMALS (3.1.2) Flashcards
Why do multi-cellular organisms require transport systems
- low SA:V volume
- high metabolic rate
- movement of substances around the body (e.g. hormones, antibodies)
What is the single circulatory system
Blood passes through the heart once to complete a circuit
Describe the circulatory system of a fish
(Single or double)
- single circulatory system
- heart pumps blood to the gills for O2
- blood then carries O2 to the rest of the body in one single circuit
What is a double circulatory system
When blood passes through the heart twice
Describe the circulatory system of a mammal
(Single or double)
- double circulatory system
1. Right side of the heart pumps blood to the lungs to pick up O2
2. Oxygenated blood travels back to the heart
3. Left side of the heart pumps the blood around the body to deliver O2
4. Deoxygenated blood returns to the right side of the heart
What is a closed circulatory system
- all vertebrates have this
- blood is enclosed inside blood vessels
Describe the circulatory system of a fish
(Closed or open)
- Heart pumps blood into arteries, branching into capillaries
- Oxygen glucose etc diffuse from blood inside capillaries into body cells
- Veins take blood back to the heart
- blood remains inside the vessels as it circulates
What is an open circulatory system
- some invertebrates
- blood flows freely in the body cavity and is not enclosed in blood vessels
Describe the circulatory system of an insect
(Open or closed)
- Segmented heart contracts in a waves, pumping blood into single main artery
- Artery opens into body cavity
- Blood flows freely around organs, making its way back into heart segments through valves
- this supplies nutrients, not O2 (this is done by the tracheal system)
Describe the structure of an artery
- folded endothelium
- elastic fibres
- smooth muscle
- collagen fibres
describe the structure of an arteriolar
- endothelium
- smooth muscle
- fewer elastic fibres
- collagen fibres
Describe the structure of capillaries
- one cell thick endothelium
Describe the structure of venules
- endothelium
- (sometimes) smooth muscle
- few collagen fibres
describe the structure of veins
- thinner endothelium
- smooth muscle
- few elastic fibres
- collagen fibres
- valves
State the function of the endothelium
- allows expansion
- maintains high pressure
- reduces friction
State the function of elastic fibres
Stretch and re-coil to maintain high pressure
state the function of smooth muscle
Thick to maintain high pressure
State the function of collagen fibres
Resist pressure
describe the pathway of blood through vessels from the heart
- Arteries
- Arteriolar
- Capillaries
- Venules
- Veins
