26 Questions
What is the primary function of the circulatory system?
To carry blood and lymph to and from the tissues of the body
Which of the following is NOT a part of the Cardiovascular system?
Lymph nodes
What is the primary function of Arteries?
To carry blood away from the heart
What is the smallest type of blood vessel?
Capillaries
What is the outermost layer of the circulatory system?
Tunica Externa
What is the function of the Internal Elastic Lamina?
To separate the tunica intima from the tunica media
What is present in the tunica media?
Concentric sheets of smooth muscle
What separates the tunica media from the tunica externa?
External Elastic Lamina
What is the primary function of postcapillary venules?
To collect blood from capillaries
What is the characteristic of tunica externa in medium-sized veins?
Longitudinal bundles of elastic fibers
What is the purpose of vein valves?
To prevent blood from flowing backward
What is a characteristic of large veins?
Thick tunica externa and longitudinal bundles of smooth muscle
What is a key difference between arteries and veins?
Arteries have thicker walls and higher blood pressure
What is a characteristic of muscular venules?
Diameter of ≤1 mm
What is a feature of the tunica intima in vein valves?
Covered on both sides by endothelium
What is a characteristic of collapsed arteries?
Small, round lumen
What is the main component of the tunica externa?
Collagen fibers
What is the function of the vasa vasorum?
To supply blood to the vascular walls
What is the characteristic of capillaries that allows for rapid exchange of substances?
Thin walls and small diameter
Which type of capillary is found in the central nervous system and thymus?
Continuous
What is the characteristic of fenestrated capillaries?
Pores in the endothelial lining
What is the function of sinusoids?
To permit free exchange of substances
What is the function of arteriovenous anastomoses?
To bypass the capillary bed
What is the characteristic of elastic arteries?
Many elastic fibers
What is the characteristic of muscular arteries?
Many muscle cells
What is the function of veins?
To collect blood from capillaries and return it to the heart
Study Notes
The Circulatory System
- The circulatory system is a transport system that carries blood and lymph to and from the tissues of the body.
Cardiovascular System
- The cardiovascular system includes the heart and vessels.
Classes of Blood Vessels
- Arteries: carry blood away from the heart.
- Arterioles: smallest branches of arteries.
- Capillaries: smallest blood vessels, allow exchange between blood and interstitial fluid.
- Venules: collect blood from capillaries.
- Veins: return blood to the heart.
Common Structure of Blood Vessels
- The wall of blood vessels consists of three layers: tunica intima, tunica media, and tunica externa (adventitia).
Tunica Intima
- Innermost layer, includes endothelial lining and connective tissue layer (subendothelial).
- Some vessels have an internal elastic lamina.
Tunica Media
- Middle layer, contains smooth muscle and connective tissue with elastic and reticular fibers.
- External elastic lamina separates tunica media from tunica externa in some vessels.
Tunica Externa
- Outer layer, composed of connective tissue sheath with collagen and elastic fibers.
Vasa Vasorum
- System of vessels that supplies blood to the vascular walls themselves.
Capillaries
- Smallest blood vessels, have small diameter and thin walls.
- Allow exchange of chemicals and gases through diffusion.
- No tunica media and externa, only endothelial cells and basal lamina.
Types of Capillaries
- Continuous: found in most tissues, have restricted permeability.
- Fenestrated: have pores in endothelial lining, allow rapid exchange of water and solutes.
- Discontinuous (Sinusoids): have a large diameter, allow free exchange of water and plasma proteins.
Arteriovenous Anastomoses
- Direct connections between arterioles and venules.
- Bypass the capillary bed, found in skeletal muscle and skin.
Artery Characteristics
- Elastic arteries: large vessels with many elastic fibers and few muscle cells.
- Muscular arteries: medium-sized vessels with many muscle cells.
- Arterioles: small vessels with little or no tunica externa and thin tunica media.
Veins
- Collect blood from capillaries and return it to the heart.
- Have three categories based on size: small veins (venules), medium-sized veins, and large veins.
- Vein valves prevent blood from flowing backward.
Vein Valves
- Folds of tunica intima covered with endothelium, prevent blood from flowing backward.
A quiz about the circulatory system, including the cardiovascular system and lymphatic system, and their components such as the heart and vessels.
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