Transport in animals Flashcards
Circulatory system in a fish
The heart pumps blood to the gills and then on through the rest of the body in a single circuit
Circulatory system in mammals
The heart is divided down the middle:
- The right side of the heart pumps blood to the lungs
- From the lungs it travels to the left side of the heart, which pumps it to the rest of the body
- When blood returns to the heart it enters the right side again
Systemic system
System in mammals where blood is sent to the rest of the body
Pulmonary system
System in mammals where blood is sent to the lungs
Advantage of the double circulatory system
The heart can give blood an extra push between the lungs and the rest of the body so the blood travels faster, so oxygen is delivered to the tissues more quickly.
What is a closed circulatory system
The blood is enclosed inside blood vessels
What is an open circulatory system
Blood isn’t enclosed in blood vessels all the time and flows freely through the body cavity
How does the close circulatory system work
1) The heart pumps blood into arteries which branch into millions of capillaries
2) Substances like oxygen and glucose diffuse from the blood in the capillaries into the body cells, but the blood stays inside the blood vessels as it circulates.
3) Veins take blood back to the heart.
How does the open circulatory system work
1) The heart is segmented. It contract in a wave, starting from the back, pumping the blood into a single main artery
2) That artery opens up into the body cavity
3) The blood flows around the insect’s organs, gradually making its way back into the heart segments through a series of valves
What does an open circulatory system supply an insect with
With nutrients and transports things like hormones around the body. It doesn’t supply the insect’s cells with oxygen though - this is done by a system of tubes called the tracheal system
What are the five types of blood vessels
Arteries, arterioles, capillaries, venules and veins
What do arteries do
Carry oxygenated (except pulmonary arteries) blood from the heart to body
Properties of arteries
- Thick muscular walls
- Elastic tissue to stretch and recoil as the heart beats, maintaining high pressure
- Inner lining (endothelium) is folded so the artery can expand helping to maintain the high pressure
What are arterioles
What arteries branch into which are much smaller
Properties of arterioles
- Has a layer of smooth muscle but less elastic tissue, this allows them to expand or contract controlling blood flow
What are capillaries
What arterioles branch into and are the smallest blood vessels and substances such as oxygen and glucose are exchanged between cells and capillaries, so adapted for efficient diffusion. Such as one cell thick walls.
What are venules
Capillaries connect to these and have thin walls that contain some muscle cells.
What are veins
Take deoxygenated (except pulmonary veins) blood back to the heart under low pressure
Properties of veins
- Wide lumen
- Little elastic tissue
- Contain valves
What is tissue fluid
The fluid that surrounds cells in tissues made from substances that leave the blood plasma such as oxygen, water and nutrients.
Does tissue fluid contain RBC or big proteins
No. They are too large to be pushed out of the capillary walls
What activity happens between cells and tissue fluid
Cells take in oxygen and nutrients from the tissue fluid, and release metabolic waste into it
What is a capillary bed
The network of capillaries in an area of tissue
How does substances move out of the capillaries into the tissue fluid
By pressure filtration
Process of pressure filtration
1) AT the start of the capillary be, nearest the arteries the hydrostatic pressure inside the capillaries is greater than the hydrostatic pressure in the tissue fluid. This difference forces fluid out of the capillaries and into the spaces around the cells, forming tissue fluid.
2) As fluid leaves, the hydrostatic pressure reduces in the capillaries so is much lower at the end of the capillary bed that’s nearest to the venules
3) At the venule end of the capillary bed, the water potential in the capillaries is lower than the WP in the tissue fluid due to fluid loss from the capillaries and the high oncotic pressure. Therefore, some water re-enters the capillaries from the tissue fluid at the venule end by osmosis.
What is oncotic pressure
The pressure exerted by the proteins in the blood plasma which lower the water potential.
Where does excess tissue fluid drain to
Lymph vessels through a drainage system called the lymphatic system