Lesson 63/64 - Circulatory systems/blood vessel & tissue fluids Flashcards
(24 cards)
What are the features of mass transport systems?
- A suitable medium in which to transport substances - usually liquid/water based
- A closed system in tubes/vessels - contains the transport medium & forms a network to distribute to all parts of the organism
- A form of mass transport - a mechanism for moving the medium within the vessels (through pressure differences) - we will look at this in animals and plants
- A mechanism to maintain the mass flow movement in 1 direction, e.g. valves
- A means of controlling the flow of transport medium to suit the changing needs of different parts of the organism.
- A mechanism for the mass flow of water/gases, e.g. intercostal muscles & diaphragm during breathing in mammals.
What is the difference between a closed and open circulatory system?
In an open circulatory system the blood doesn’t move around the body in blood vessels but bathes the tissues directly. In a closed circulatory system the blood moves in blood vessels
What is the difference between a single circulatory system and a double circulatory system?
Single circulatory system: the blood moves through the heart once in its passage through the body.
Double circulatory system: the blood passes through the heart twice in its circuit around the body – e.g. blood pumps from heart to lungs, then returns to heart from lungs and is then pumped again from heart to the rest of the body
What is an advantage of a double circulatory system? What would increase the need for a double circulatory system?
Double circulation is more efficient than single circulation because the oxygenated blood can be pumped around the body at higher pressure. Organisms that are more active/have a higher metabolic rate will have greater need for a double circulatory system
Which blood vessel is the most abundant?
capillaries
Which blood vessel is the widest?
Veins
Which blood vessel has the thickest walls?
Arteries
What does the blood transport?
Respiratory gases, products of digestion, metabolic waste and hormones
Where does the vena cava carry blood to?
Deoxygenated blood to the heart
Where does the aorta carry blood to?
Oxygenated blood to the body
Where does the pulmonary artery carry blood to?
Deoxygenated blood to the lungs
What are the functions of the arteries?
- Carry blood from heart to blood
- Walls are thick/muscular to withstand the high pressure
- Walls have elastic tissue to stretch/recoil as the heart beats, maintains high pressure
- All arteries carry oxygenated blood, except pulmonary arteries, which take deoxygenated blood to the lungs
What are the functions of the arterioles?
- They are the smaller vessels the arteries divide into
- They form a network throughout the body
- They contract to resist blood flow or relax to allow blood flow
What are the functions of the veins?
- Take blood back to the heart under low pressure
- Wider lumen than arteries, with very little elastic/muscle tissue
- Contain valves to prevent backflow of blood
- Body muscles surrounding veins contract to help with blood flow
- All veins carry deoxygenated blood (as O2 has been used up by the body cells), except pulmonary veins, which carry oxygenated blood to the heart from the lungs
What are the functions of the capillaries?
- These are what arterioles branch off into, They’re the smallest blood vessels
- Substances (glucose/O2) are exchanged between cells and capillaries by diffusion
- The walls are only 1 cell thick, shortens the diffusion pathway
- Large number of capillaries, to increase SA for exchange
- Networks of capillaries in tissue are called capillary beds
What happens to tissue fluid in a capillary bed, surrounded by an arteriole at 1 end and a venule at the other?
Arteriole end of capillary: Higher hydrostatic pressure in capillaries than in tissue fluid, so fluid is forced out of capillary
Venule end of capillary: Lower water potential in capillaries than in tissue fluid, so some water re-enters capillary by osmosis.
What is high blood pressure caused by?
A high hydrostatic pressure in the capillaries, which can lead to an accumulation of tissue fluid in the tissues.
Why is pressure highest at the start of the capillary bed nearest the arterioles?
The left ventricle contracts and sends blood out of the heart, through the arteries and arterioles at high pressure.
What is the order that the blood moves through the heart?
Pulmonary vein
Left atrium
Left atrioventricular valve
Left ventricle
Left semi-lunar valves
Aorta
What is tissue fluid?
- The solution/watery liquid surrounding cells, their immediate environment (it bathes all the cells in the body)
- It is formed by the filtration of blood plasma through capillary endothelial pores (fenestra)
- It’s the means by which substances are exchanged between cells and the blood
What does tissue fluid supply cells with and what does it receive?
- Tissue fluid supplies cells with the following - glucose, amino acids, fatty acids, ions and oxygen
- It receives carbon dioxide and other waste materials
What is the lymphatic system?
- It consists of a network of lymphatic vessels carrying a clear liquid called lymph
- It helps to get rid of the body’s toxins, waste and other unwanted material produced by cells
- It transports white blood cells throughout the body to help fight infections (part of the body’s immune system)
What does lymph transport back into the blood?
- Tissue
- Interstitial fluid
How is lymph moved along lymph vessels?
By pressure gradients and contraction of body muscles that squeeze the lymph alone (contain valves)
