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Blood vessels contribute to homeostasis by
- providing the structures for the flow of blood to and from the heart
- the exchange of nutrients and wastes in tissues.
- play an important role in adjusting the velocity and volume of blood flow.
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Cardiovascular system contributes to homeostasis of other body systems by
- transporting and distributing blood throughout the body to deliver materials (such as oxygen, nutrients, and hormones)
- carry away wastes.
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The five main types of blood vessels
- arteries,
- arterioles,
- capillaries,
- venules,
- veins
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What are Arteries and what do they do
- carry blood away from the heart to other organs.
- Large, elastic arteries leave the heart divide into medium-sized, muscular arteries that branch out into the various regions of the body.
- Medium-sized arteries then divide into small arteries, which in turn divide into still smaller arteries called arterioles (ar-TĒR-ē-ōls)
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|What are arterioles and what do they do
- medium sized arteries divide into smaller arteries called arterioles
- Arterioles enter a tissue, they branch into numerous tiny vessels called capillaries
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Capillaries what are they
- allow the exchange of substances between the blood and body tissues.
- Groups of capillaries within a tissue reunite to form small veins called venules (VEN-ūls).
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What are Venules and Veins
- Caillaries group and reunite to form small veins called venules
- these in turn merge to form progressively larger blood vessels called veins.
- Veins (VĀNZ) are the blood vessels that convey blood from the tissues back to the heart.
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Angiogenesis
- refers to the growth of new blood vessels.
- It is an important process in embryonic and fetal development,
- serves important functions such as wound healing, formation of a new uterine lining after menstruation, formation of the corpus luteum after ovulation, and development of blood vessels around obstructed arteries in the coronary circulation.
- Several proteins (peptides) are known to promote and inhibit angiogenesis.
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Which vessel—the femoral artery or the femoral
vein—has a thicker wall? Which has a wider lumen?
- The femoral artery has the thicker wall; the femoral vein has the wider
- lumen.
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The wall of a blood vessel consists of three layers, or tunics, of different
tissues
- an epithelial inner lining,
- a middle layer consisting of a smooth muscle and
- elastic connective tissue,
- a connective tissue outer covering.
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three structural layers of a blood vessel
both vein & artery
- the tunica interna (intima) - innermost
- tunica media
- tunica externa - outermost
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Arteries n Veins carry blood ....
- Arteries carry blood from the heart to tissues
- veins carry blood from tissues
- to the heart.
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The tunica interna
- forms the inner lining of a blood vessel and is in direct contact with the blood
- as it flows through the lumen, or interior opening, of the vessel
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The tunica media (media =middle) is
- a muscular and connective tissue layer that displays the greatest variation among the different vessel types
- In most vessels, it is a relatively thick layer
- comprised mainly of smooth muscle cells and substantial amounts of elastic fibers.
- The primary role of the smooth muscle cells, which extend circularly around the lumen like a ring encircles your finger, is to regulate the diameter of the lumen
- In addition to regulating blood flow and blood pressure, smooth muscle contracts when vessels are damaged to help limit loss of blood through the injured vessel,
- smooth muscle cells help produce the elastic fibers within the tunica media that allow the vessels to stretch and recoil under the applied pressure of the
- blood.
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the tunica externa
- outer covering of a blood vessel,
- consists of elastic and collagen fibers
- Separating the tunica externa from the tunica media
- is a network of elastic fibers, the external
- elastic lamina
which is part of the tunica media. The tunica externa contains numerous nerves and, especially in larger vessels, tiny blood vessels - that supply the tissue of the vessel wall.
- These small vessels that supply blood
- to the tissues of the vessel are called vasa vasorum (vas = vessel), or vessels to the vessels.
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Elastic arteries are the largest or smallest arteries?
- are the largest arteries in the body,
- ranging from the garden hose–sized aorta
- and pulmonary trunk to the finger-sized branches of the aorta.
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What is Elastic Lamellae
- Elastic Arteries...These vessels are characterized by well-defined internal and external elastic
- laminae, along with a thick tunica media that is dominated by elastic fibers,
- called the elastic lamellae
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What are the 2 major trunks that exit the heart?
- Elastic arteries include the two major trunks that exit the heart (the aorta and
- the pulmonary trunk),
- along with the aorta's major initial branches,
- such as the brachiocephalic, subclavian, common carotid, and common iliac arteries
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aorta's major initial branches
- brachiocephalic,
- subclavian,
- common carotid
- common iliac arteries
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All veins of the symatic circulation drain into the
- Superior Vena Cava,
- Inferior vena cava
- or coronary sinus
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three different types of capillaries
- continuous capillaries,
- fenestrated capillaries,
- and sinusoids
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How do materials move through capillary walls
- Materials cross capillary walls through intercellular clefts and fenestrations,
- via transcytosis in pinocytic vesicles, and through the plasma membranes of
- endothelial cells
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venules that initially receive blood from capillaries are called
postcapillary venules
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Valves in veins allow blood to flow in one direction only...
what way?
towards the heart
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Why are valves more important in arm veins and
leg veins than in neck veins
- because, when you are standing, gravity causes pooling of blood in the veins of
- the free limbs but aids the flow of blood in neck veins back toward the heart.
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