13 - Blood Vessels and Circulation Flashcards
What are the functions of the circulatory system?
- Carry blood
- Exchange nutrients, waste products, and gases with tissues.
- Transports substances.
- Helps regulate blood pressure
- Directs blood flow to the tissues.
Blood vessels outside the heart are divided into two classes:
Pulmonary vessels, which transport blood to the lungs and back to the heart, and the Systemic vessels which transport blood through all parts of the body.
Blood flows through different types of arteries and veins. Name them, starting with the heart.
Arteries - Small Arteries - Arterioles -Capillaries - Venules - Small Veins - Veins
The tunics are the three layers of blood vessel walls. These are present in all but which types of blood vessels?
Tunics are not present in the capillaries and venules.
Name the three different layers of the tunics.
- Tunica intima, 2. Tunica media, 3. Tunica externa/adventitia
Describe the structure of the tunica intima, the innermost of the tunics.
Consists of an endothelium composed of simple squamous epihelial cells, a basement membrane, and a small amount of connective tissue.
Describe the structure of the tunica media, the middle layer of the tunics.
Consists of smooth muscle cells arranged circularly around the blood vessel. It also contains variable amounts of elastic and collagen fibers.
Describe the structure of the tunica externa/avdentitia
Composed of dense connective tissue, the tissue becomes loose connective tissue toward the outer portion of the blood vessel wall.
The arteries can be divided into two different types. Which?
The elastic arteries and the muscular arteries.
What are the physical properties of elastic arteries?
Elastic arteries are the largest-diameter arteries and have the thickest walls. Compared to other arteries, a greater proportion of their walls is composed of elastic tissue.
What are the functions of elastic arteries?
The elastic recoil of these arteries prevents blood pressure from falling rapidly and maintains blood flow while the ventricles are relaxed.
What are the physical properties of muscular arteries?
The walls are relatively thick compared to heir diameter. Most of the wall’s thickness results from smooth muscle cells of the tunica media.
Another name for muscular arteries is distributing arteries. Why?
Because the smooth muscle tissue enables these vessels to control blood flow to different body regions.
What is vasoconstriction?
The contraction of smooth muscle in blood vessels. Decreases blood flow.
What is vasodilation?
The relaxation of smooth muscle in blood vessels. Increases blood flow.
How is blood flow in the capillaries regulated?
By precapillary sphincters located at the origin of the capillary branches.
What are the physical properties of capillaries?
They consists of endothelium walls, which is a layer of simple squamous epithelium surrounded by a delicate loose connective tissue. Also have precapillary sphincters.
What are the physical properties of venules?
They do not have the tunic structure, but constists of endothelium resting on a delicate connective tissue layer.
Which veins have valves?
Those that have a diameter of more than 2mm.
Describe the blood vessels of the pulmonary circulation. Mention the names of the vessels and the exit and entrance to the heart.
Blood from the right ventricle is pumped into a short vessel called the pulmonary trunk. The pulmonary trunk then branches into the right and left pulmonary arteries, each extending to its own lung. Four pulmonary veins exit the lungs and carry the oxygen-rich blood to the left atrium.
What are varicose veins? På norsk: Åreknuter.
Varicose veins result when the veins of the lower limbs become so dilated that the cusps of the valves no longer overlap to prevent the backflow of blood.
Explain how varicose veins can be dangerous to your health.
The blood in varicose veins can become so stagnant that it clots, creating tromboses. Can cause inflammation of the veins, phlebitis(årebetennelse). Can also lead to an infection by anaerobic bacteria: gangrene(koldbrann).
What is an arterial aneurysm?
A localized dilation of an artery that usually develops in response to trauma or a congenital weakness of the artery wall. Rupture of a large aneurysm in the aorta is almost always fatal.
Define congenital.
A condition existing at birth. Medfødt lidelse.
The aorta is usually considered in three parts, which?
The ascending aorta, the aortic arch, and the descending aorta.
What is a portal system?
A vascular system that begins and ends with capillary beds and has no pumping mechanism, such as the heart.
What is “the coronary bypass surgery”?
Portions of the great saphenous vein (the vein on the inside of each foot), are grafted to create a route for blood flow that bypasses blocked portions of the coronary arteries. Sometimes the femoral vein is used instead.
What is blood pressure?
Blood pressure is a measure of the force blood exerts against the blood vessel walls. The standard unit for measuring blood pressure is millimeters of mercury (mm Hg).
In arteries, blood pressure values go through a cycle that depends on the rythmic contractions of the heart. Which two types of pressure?
Systolic pressure, when the ventricles contract. Diastolic pressure when the ventricles relax.
Systolic pressure is when the ventricles are…
contracted.