Circulatory system/ Blood Vessels Flashcards
(20 cards)
What two key terms describe the mammalian circulatory system? What do these terms actually mean?
- Closed: the blood remains within the blood vessels.
- Double circulatory system: Blood passes through heart twice in each circuit. One circuit = delivers blood to the lungs.
Another circuit: delivers blood to the rest of the body.
Why do mammals require a double circulatory system?
- Mammals require a double circulatory system to manage the pressure of blood flow.
What is the pressure of blood flow like to the lungs and why?
two main reasons as to WHY.
- Blood flows through the lungs at lower pressure.
- Prevents damage to capilaries in alveoli.
- Reduces speed at which blood flows, enabling more time for gas exchange.
What is the pressure of blood flow like from the heart to the rest of the body? Why?
- Blood is pumped at a higher pressure to the rest of the body.
- Important to ensure blood reaches all respiring cells in the body.
What are the 4 main blood vessels attached to the heart that you need to know?
- Vena cava (vein)
- Aorta (artery.)
- Pulmonary artery
- Pulmonary vein.
What are the two main blood vessels attached to lungs that you need to know about?
- Pulmonary artery.
- Pulmonary vein.
What are the two main blood vessels attached to the kidneys?
- Renal artery.
- Renal vein.
What are the 4 TYPES of major blood vessels connected within circulatory system?
- Arteries.
- Arterioles.
- Capilaries
- Veins.
Give the functions of the:
- arteries
- arterioles
- capilaries
- veins
- Arteries: carry blood away from heart into arterioles.
- Arterioles: smaller than arteries, connect the arteries to capilaries.
- Capilaries: connect arterioles to veins.
- Veins: carry blood back into the heart.
What do many capilaries form together, what is the importance of this?
- Many branched capilaries form capilary beds as exhange surfaces.
- All the capillaries in the capillary bed have a narrow diameter to slow blood flow.
- Red blood cells can only just about fit through the capilaries, maximising the rate of diffusion.
Muscle layer, elastic layer, OVERALL wall thickness and valves in arteries and WHY?
- Muscle layer: thickER than veins so that constriction and dilation can occur to control volume of blood.
- Elastic layer: thickER than veins to help maintain blood pressure. Walls can stretch and recoil.
- OVERALL wall thickness: thicker wall than veins to help prevent the vessels bursting due to high pressure.
- Valves: NONE!
In diagrams of the valves, describe where the elastic layer/ muscle layer are?
- Elastic layer is the one directly on inside of lumen.
- Muscle layer is thicker than elastic layer, the layer surrounding the elastic layer.
Refer to diagram if needs be.
Muscle layer, elastic layer, OVERALL wall thickness and valves in veins and WHY?
- Muscle layer: relatively thin so it cannot control the blood flow.
- Elastic layer: relatively thin as pressure is much lower.
- Wall thickness: thin as pressure is much lower, so low risk of bursting. Thinness means vessels are easily flattened, which helps flow of blood up to heart.
- Valves: YES.
Muscle layer, elastic layer, OVERALL wall thickness and valves in arterioles and WHY?
- Muscle layer: Thicker than in arteries to help restrict blood flow into the capilaries.
- Elastic layer: Thinner than in arteries, as pressure is lower.
- OVERALL wall thickness: Thinner as pressure is slightly lower.
- Valves: No.
Muscle layer, elastic layer, OVERALL wall thickness and valves in capilaries and WHY?
- Muscle layer: NONE!
- Elastic layer: NONE!
- OVERALL wall thickness: one cell thick - only lining layer –> short diffusion distance for exchanging materials between the blood and cells.
- Valves: NONE!
Exam Q
Explain how an arteriole can reduce the blood flow into capillaries.
- Muscle contracts
- Constricts/ narrows arteriole.
June 2016 paper 2.
Some drugs used to reduce high ventricular blood pressure cause widening of blood vessels
Suggest how widening of blood vessels can reduce ventriular blood pressure (2)
- Larger lumen
- Less friction.
Which vessel carries blood at lowest pressure AND why?
- Vena cava
- Carries deoxygenated blood.
Describe what arterioles do during exercise (2 marks)
- Muscle relaxes
- Widens blood vessel, so, increased blood flow during exercise.
How does arteriole reduce blood flow? (1 mark)
- By contracting/ narrowing arteriole lumen.
