A&P1 - LP#7 Flashcards
Blood Vessels Blood Cells Immunity & Lymphatic System
There are FIVE main types of blood vessels:
- Arteries
- Arterioles
- Capillaries
- Venules
- Veins
_________ can carry blood away from the heart to other organs. They leave the heart eventually branching into medium sized versions of themselves.
Arteries
After branching into medium sized arteries, they further branch into smaller vessels called ____________.
Aterioles
As arterioles enter a tissue, they branch into numerous tiny vessels called ___________.
Capillaries
Groups of capillaries within a tissue reunite to form small veins called _____________.
Venules
Venules merge to form progressively large blood vessels called ____________ that return blood back to the heart.
Veins
_________________ refers to the growth of new blood vessels.
Angiogenesis
The wall of a blood vessel consists of three layers, or ___________.
Tunics
What are the three structural layers of generalized blood vessel from innermost to outer most layer:
- Tunica Interna (Intima)
- Tunica Media
- Tunica Externa
The Tunica ____________ forms the inner lining of blood vessels, comes in direct contact with the blood flow in the lumen. Made up of epithelial cells called endothelium.
Tunica Interna (Intima)
The Tunica __________ is the middle layer. It is relatively think layer of smooth muscle cells and has elastic fibres. It’s primary role is to regulate the diameter of the lumen. It helps contract vessels when they are damaged, this minimizes blood loss. This layer has the greatest display of variation among the different vessel types.
Tunica Media
The Tunica __________ is the outer layer. It is made up of elastic and collagen fibers, separating the layers in a network of elastic fibres. It contains lots of nerves and tiny blood vessels
Tunica Externa
___________ have thicker muscle and elastic portions in the tunica media. High compliance because of elastic fibres. Their walls will easily stretch or expand without tearing in response to pressure. Sympathetic fibres of the ANS innervate the smooth muscle of blood vessels. An increase in sympathetic stimulation causes the smooth muscle to contact - squeezes the vessel wall and narrows the lumen. Can vasodilate and vasoconstrict.
Arteries
Two types of arteries:
- Elastic Arteries
2. Muscular Arteries
Function of Elastic Arteries:
Propel blood onward while ventricles relax and blood is ejected from the heart.
Move blood from the heart to the medium sized arteries.
Function of Muscular Arteries:
Ability to contract and maintain vascular tone.
Distributing arteries - they continue to branch and distribute blood to various organs & systems.
______________ is a union of branches of two or more arteries supplying the same region. Provides alternative route for blood flow to reach organ/tissue. Can occur between arterioles and venules.
Anastomosis
What is the function of an Arteriole
Regulate the blood flow from arteries into the capillary beds.
Resistance vessels - Prevents/decreases blood floor with vasoconstriction of smooth muscle of the vessel.
___________ are the smallest vessels in the circulatory system. They are thin walled and lack a tunica media and externa. The walls consist of only a single layer of endothelial cells and a basement membrane.
They are exchange vessels and enable the exchange of substances between the blood and interstitial fluid.
Capillaries
There are THREE types of Capillaries
- Continuous Capillaries
- Fenestrated Capillaries
- Sinusoids
The most abundant type of capillaries. The plasma membranes of endothelial cells form a continuous tube that is interrupted by intercellular clefts
Found in: brain, lungs, skeletal and smooth muscle and CT.
Continuous Capillaries
The plasma membranes of endothelial cells in these capillaries have fenestration’s (small pores/windows),
Found in the kidneys, villi of small intenstine, ventricles of the brain and in endocrine glands.
Fenestrated Capillaries
This type of capillary is wider and more winding then the others. Endothelial cells with larger fenestrations; large intercellular clefts that allow proteins and sometimes blood cells to pass from a tissue to the bloodstream. They have specialized lining cells that are adapted to the functions of the tissue.
Sinusoids
This type of venous blood vessel drains capillary blood and begin the return of blood flow back toward the heart. Because of pores, it functions as significant sites of exchange of nutrients and wastes and white blood cell emigration. Therefore form the microcirculatory exchange unit of the capillaries.
Venules