Back to AI Flashcard MakerBiology /Biology IB HL - 6.2 The Blood System Part 2
What are arterioles similar in structure to? What is the difference?
Arterioles are similar in structure to arteries, but they have a lower proportion of elastic fibres and a large number of muscle cells
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Key Terms
Term
Definition
What are arterioles similar in structure to? What is the difference?
Arterioles are similar in structure to arteries, but they have a lower proportion of elastic fibres and a large number of muscle cells
Why are muscle cells present in arterioles? Give an example
The presence of muscle cells allows them to contract and close their lumen to regulate blood flow to specific organs Eg. during exercise blood flow to...
What must arteries and to a certain extent arterioles withstand?
Arteries, and to a slightly lesser extent arterioles, must be able to withstand high pressure generated by the contracting heart, and both must mainta...
What is important in maintaining the blood pressure?
Muscle and elastic fibres in the arteries help to maintain the blood pressure as the heart contracts and relaxes
What is systolic pressure?
Systolic pressure is the peak pressure point reached in the arteries as the blood is forced out of the ventricles at high pressure
What does systolic pressure cause?
At this point, the walls of the arteries are forced outwards, enabled by the stretching of elastic fibres
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| Term | Definition |
|---|---|
What are arterioles similar in structure to? What is the difference? | Arterioles are similar in structure to arteries, but they have a lower proportion of elastic fibres and a large number of muscle cells |
Why are muscle cells present in arterioles? Give an example | The presence of muscle cells allows them to contract and close their lumen to regulate blood flow to specific organs Eg. during exercise blood flow to the stomach and intestine is reduced while blood flow to the muscles increases |
What must arteries and to a certain extent arterioles withstand? | Arteries, and to a slightly lesser extent arterioles, must be able to withstand high pressure generated by the contracting heart, and both must maintain this pressure when the heart is relaxed |
What is important in maintaining the blood pressure? | Muscle and elastic fibres in the arteries help to maintain the blood pressure as the heart contracts and relaxes |
What is systolic pressure? | Systolic pressure is the peak pressure point reached in the arteries as the blood is forced out of the ventricles at high pressure |
What does systolic pressure cause? | At this point, the walls of the arteries are forced outwards, enabled by the stretching of elastic fibres |
What is diastolic pressure? | Diastolic pressure is the lowest pressure point reached within the artery as the heart relaxes |
What happens to the arterial wall during diastolic pressure? | At this point, the stretched elastic fibres recoil and force the blood onward through the lumen of the arteries |
What does the arterial wall's response to systolic and diastolic pressure maintain? | This maintains high pressure throughout the heart beat cycle |
What is vasoconstriction? | Vasoconstriction of the circular muscles of the arteries can increase blood pressure by decreasing the diameter of the lumen |
What is vasodilation? | Vasodilation of the circular muscles causes blood pressure to decrease by increasing the diameter of the lumen |
What are capillaries and what is their function? | Capillaries provide the exchange surface in the tissues of the body through a network of vessels called capillary beds |
What is the wall of a capillary made of? | The wall of a capillary is made from a single layer of endothelial cells (this layer is also found lining the lumen in arteries and veins) |
Why is the wall of a capillary one cell thick? | Being just one cell thick reduces the diffusion distance for oxygen and carbon dioxide between the blood and the tissues of the body |
What is between the endothelial cells of a capillary? What does this form? | The thin endothelium cells also have gaps between them called pores which allow blood plasma to leak out and form tissue fluid |
What does tissue fluid contain? | Tissue fluid contains oxygen, glucose and other small molecules from the blood plasma |
What does tissue fluid not contain? | Large molecules such as proteins usually can't fit through the pores into the tissue fluid |
Where is tissue fluid found? Why? | Tissue fluid surrounds the cells, enabling exchange of substances such as oxygen, glucose, and carbon dioxide |
What regulates the amount of tissue fluid that seeps out? | The permeability of capillaries can vary depending on the requirements of a tissue |
What is the diameter of the lumen of capillaries? | Capillaries have a lumen with a small diameter |
What does the small diameter of capillaries allow for? | Red blood cells squeeze through capillaries in single-file This forces the blood to travel slowly which provides more opportunity for diffusion to occur |
What is a capillary bed? | Capillaries form branches in between the cells; this is the capillary bed |
What is the purpose of capillary beds? | These branches increase the surface area for diffusion of substances to and from the cells Being so close to the cells also reduces the diffusion distance |
How does pressure change from arterioles to capillaries? | Arteries split into arterioles which in turn split into capillaries, decreasing arterial pressure as total vessel volume is increased |
Why is it useful for blood pressure to decrease from arterioles to capillaries? | The branching of arteries into capillaries therefore ensures blood is moving slowly and all cells are located near a blood supply |