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Questions and Answers
What is the main function of valves in veins?
What is the main function of valves in veins?
- To decrease blood volume
- To prevent backflow of blood (correct)
- To carry oxygenated blood
- To increase blood pressure
Veins have a thick tunica media and a narrow lumen.
Veins have a thick tunica media and a narrow lumen.
False (B)
What characteristic of veins helps them withstand low pressure?
What characteristic of veins helps them withstand low pressure?
Large lumen and tunica externa
Veins have a relatively low percentage of ______ and smooth muscle compared to arteries.
Veins have a relatively low percentage of ______ and smooth muscle compared to arteries.
Match the following features with their respective types of blood vessels:
Match the following features with their respective types of blood vessels:
What is the primary role of arteries in the circulatory system?
What is the primary role of arteries in the circulatory system?
Capillaries are thicker than arteries.
Capillaries are thicker than arteries.
What is the name of the layer that provides strength to blood vessels?
What is the name of the layer that provides strength to blood vessels?
The ___ are the smallest blood vessels where gas exchange occurs.
The ___ are the smallest blood vessels where gas exchange occurs.
Match the type of blood vessel to its function:
Match the type of blood vessel to its function:
Which of the following statements is true regarding the tunica media of arteries?
Which of the following statements is true regarding the tunica media of arteries?
Veins have a narrow lumen compared to arteries.
Veins have a narrow lumen compared to arteries.
What process allows capillary walls to facilitate the exchange of substances?
What process allows capillary walls to facilitate the exchange of substances?
The smooth layer lining the innermost part of blood vessels is called the ___.
The smooth layer lining the innermost part of blood vessels is called the ___.
What are the small gaps between squamous epithelial cells in capillaries called?
What are the small gaps between squamous epithelial cells in capillaries called?
The contraction of ventricles generates high blood pressure within the arteries.
The contraction of ventricles generates high blood pressure within the arteries.
Name the process by which muscle fibers in arterioles can limit blood flow.
Name the process by which muscle fibers in arterioles can limit blood flow.
The blood pressure inside capillaries is ___ compared to arteries.
The blood pressure inside capillaries is ___ compared to arteries.
Match each blood vessel with its description:
Match each blood vessel with its description:
Flashcards
Vein Lumen Size
Vein Lumen Size
Veins have a large lumen (central opening) which allows for the passage of blood under low pressure back to the heart. This is in contrast to arteries which have smaller lumens due to higher blood pressure.
Vein Tunica Media
Vein Tunica Media
Veins have a thin tunica media, a layer of smooth muscle and elastic fibers, compared to arteries due to lower blood pressure in veins.
Vein Valves
Vein Valves
Veins have valves to prevent backflow of blood, especially against gravity. This ensures blood flows in one direction towards the heart.
Vein Tunica Externa
Vein Tunica Externa
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Artery vs Vein Structure
Artery vs Vein Structure
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Arteries
Arteries
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Arterioles
Arterioles
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Capillaries
Capillaries
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Venules
Venules
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Veins
Veins
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Tunica Externa
Tunica Externa
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Tunica Media
Tunica Media
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Tunica Intima
Tunica Intima
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Lumen
Lumen
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Vasoconstriction
Vasoconstriction
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Vasodilation
Vasodilation
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Fenestrations
Fenestrations
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Diffusion
Diffusion
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Tissue Fluid
Tissue Fluid
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Capillary Network
Capillary Network
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Study Notes
Blood Vessel Structure and Function
- Arteries: Carry blood away from the heart under high pressure.
- High pressure is created by ventricular contraction.
- Arteries help maintain this high pressure.
- Arteries branch into smaller arterioles.
- Arterioles lead to capillaries.
Capillaries
- Capillaries are one cell thick.
- Tissue fluid leaves the blood in capillaries to bathe cells.
- Capillaries connect to venules.
- Venules lead to veins.
Blood Vessel Layers
- Tunica externa: Outer layer, made of collagen for strength.
- Tunica media: Middle layer, contains smooth muscle and elastic fibers.
- Smooth muscle controls blood flow.
- Elastic fibers maintain high pressure (stretch and recoil).
- Tunica intima: Inner lining, made of squamous epithelial cells for smooth surface, reducing friction.
- Lumen: The central space through which blood flows.
Arteries (detailed)
- Narrow lumen due to thick tunica media.
- Tunica media contains elastic fibers and smooth muscle.
- Elastic fibers maintain high blood pressure through stretching and recoiling (not the role of smooth muscle).
- Smooth muscle assists in regulating blood flow, but primarily is a regulator, not a direct pressure-maintaining factor.
- The tunica externa provides structural support.
Arterioles (compared to arteries)
- Similar structure to arteries, but have less elastic fibers.
- Blood pressure is lower compared to arteries.
- Smooth muscle plays an important role in vasoconstriction and vasodilation (controlling blood flow).
Capillaries (detailed)
- Extremely thin walls (single cell thick), composed of squamous epithelial cells.
- Smooth inner lining minimizes friction.
- Fenestrations (small gaps) facilitate substance exchange (e.g., oxygen, carbon dioxide).
- Extensive capillary networks provide a large surface area for exchange.
- Blood pressure drops significantly in capillaries.
- Diffusion distance between capillaries and tissues is short.
Venules and Veins
- Veins: Carry blood back to the heart under low pressure.
- Wide lumen accommodates lower pressure.
- Thin tunica media with less elastic fiber, enabling easier movement of blood.
- Tunica External: Still present for structural support.
- Valves: Present in veins to prevent backflow (due to gravity), maintaining blood flow towards the heart.
- Photomicrograph comparison: Arteries have a thick wall and narrow lumen; veins have a wide lumen and thin wall.
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