Blood vessels Flashcards
Name the five general types of blood vessels in the cardiovascular system.
- Arteries
- carry blood AWAY from the heart
- branch to form smaller arteries, when then get so small, they are called arterioles - Arterioles
- muscular walls
- carry blood into capillaries
Known as resistance vessels,
- when it vasoconstricts, the tissues served are largely bypassed
- when it dilates, blood flow into the local capillaries/ capillary bed increases dramatically - Capillaries
-SMALLEST BLOOD VESSELS
- sites exchange between blood and tissue
- largest area is slowest flow
-thin walled - Venules
- carry blood back to the heart
- at the end of capillaries, they converge to form venules until they’re big enough to be called a vein - Veins.
- returns blood from body regions back to the heart
Describe the general difference(s) between the systemic and pulmonary circulation.
pulmonary circulation
- short loop that runs from the heart to the lungs and back to the heart
systemic circulation
-long loop go all parts of the body before running to the heart
Name from innermost to outermost the three distinct tissue layers (i.e., tunics) of the
blood vessel walls.
outermost to innermost
tunica externa
- made of loosely woven collagen fibers that protect and reinforce the vessel , anchoring it to surrounding structures
- in larger vessels, the tunica contains a tiny system of blood vessels called the vasa vasorum that nourish the more external tissues of the blood vessel wall.
tunica media
-mostly circularly arranged smooth muscle cells and sheets if elastin
- activity of the smooth muscle is regulated by sympathetic vasomotor nerve fibers of the ANS
- regulation causes constriction of dilation
- regulate circulatory dynamics because changes in vessel dynamics influence blood flow and pressure
- BULKIEST LAYER
- maintain BP and circulation
tunica intima
- in intimate contact with the blood in the lumen.
contains the endothelium that is continuous with the endocardial lining of the heart, its flat cells fit closely together and minimize friction as blood moves through the lumen
- Describe the general composition of each of the tissue layers named above (#3). How
does the layer composition vary among the six types of vessels you identified above
(#1)?
tunica externa
- made of loosely woven collagen fibers that
tunica interna/intima: endothelium, simple squamous epithelium with slick surface
can contain sub endothelial layer with connective tissue
tunica media: circular smooth muscle cells and sheets of elastin, bulky
tunica adventitia: loose collagen fibers, infiltrated with nerve fibers, lymph vessels, and elastic fibers
elastic artery: low endo, highest elastic, norm smooth, low fibrous
muscular artery: low endo, low elastic, highest smooth, high fibrous
arteriole: low endo, low elastic, norm smooth, norm fibrous
capillary: low endo, no elastic, no smooth, no fibrous
venule: low endo, no elastic, low smooth, low fibrous
vein: low endo, lowest elastic, norm smooth, high fibrous
tunica interna/intima: constant endothelium level in each
tunica media: more in arteries, less in veins (none in thin)
tunica adventitia: most in vein, muscular artery and none in capillaries
As you study the vascular system, you will encounter the following tissues: simple
squamous ET, dense fibrous CT, elastic CT, areolar tissue, smooth muscle. Describe
the general structure and function of each of these tissues.
simple squamous ET- dingle layer of flattened cells with disc shaped central nuclei and space cytoplasm (the simplest epithelium)
function:
*allows materials to pass by diffusion and filtration in sites where protection is not important
*secretes lubricating substances in serosae (lining of ventral body cavity)
dense fibrous CT-In the dense connective tissue fibroblast cells are organized between the rows of the fibers. Fibroblast cells generate collagen fibers for the connective tissue.
function: Dense connective tissue supports, protects, and holds bones, muscles, and other tissues and organs in place. Ligaments, tendons, the inner layer of the skin, and the sclera (the white outer layer of the eye) are all types of dense connective tissue. Also called fibrous connective tissue.
elastic CT-
areolar tissue- Areolar connective tissue is a type of dense, irregular connective tissue found in the human body. It consists mainly of a network of fibres and cells which are held together by a gel-like matrix.
function: Areolar connective tissue is the type of tissue which connects and surrounds different organs in the human body. The important function of this type of tissue is that it provides nutrition to the cells and also acts as a cushion to protect the organs from various external forces.
smooth muscle-Smooth muscle consists of thick and thin filaments that are not arranged into sarcomeres giving it a non-striated pattern
function: Smooth muscle consists of thick and thin filaments that are not arranged into sarcomeres giving it a non-striated pattern
Which layer of the blood vessel wall is continuous with the endocardium of the heart?
tunica intima
What effect does the sympathetic nervous system have on vascular smooth muscle tone?
increase in sympathetic activity=constriction of vascular smooth muscle tone
decrease in sympathetic flow=vasodilation of vascular smooth muscle tone
Identify the three basic types of arterial vessels and describe the structural and functional
differences between them.
elastic arteries: thick walled, near the heart, largest in diameter, most elastin, low resistance conducting aa., pressure reservoirs which expand and recoil for blood ejection
muscular arteries: distributing aa. deliver blood to specific body organs, most aa., thickets tunica media so active in vasoconstriction, less stretch
arterioles: small diameter, smooth muscle, lead to capillary bed, dramatic constriction/dilation
Which arterial vessels serve as a pressure reservoir between contractions of the
ventricles?
elastic arteries
Which arterial vessels help to distribute blood to specific body organs or regions of the
body?
muscular arteries
Why are the arterioles called the resistance vessels of the vascular system?
because their constriction and dilation dramatically effects where blood flow goes
Which arterial vessels play the most important role in regulating blood flow into
capillary beds and in regulating blood pressure?
arterioles
Identify and describe the arterial vessel which directly supplies a capillary bed.
metarteriole is intermediate between arterioles and capillary bed,
contains a wall structure that is transitional which consists of an endothelial layer that is surrounded externally by smooth muscle cells (called perisites) which circle around the outside of the endothelial layer
each metarteriol branches off an arteriole into capillaries
What role do the precapillary sphincters play in regulating blood flow to the capillaries?
surrounds the root of each capillary at the met arteriole and acts as a valve to regulate blood flow into the capillary, depends on proliferation needs
What is the relationship between a metarteriole and a thoroughfare channel?
metarteriole is continuous with thoroughfare at the vascular shunt venule end
