Flashcards in A&P Chapter 20 Blood Vessels Deck (24):
What blood pressure do the blood vessels produce?
The Diastolic Blood Pressure
What is the definition of an artery?
A vessel that carries blood from the heart to capillaries.
What is the definition of a vein?
A vessel that carries blood from capillaries to the heart.
What is the Systemic Circuit?
Everything except the Pulmonary Circuit. This includes the coronary blood flow.
What is the Pulmonary Circuit?
The blood flow leaving the Right Ventricle travelling up the Pulmonary trunk to the Right and Left Pulmonary Arteries to the capillaries of the lungs and back through the Pulmonary Veins to the Left Atrium.
They carry blood from the heart to capillaries.
They have a higher pressure than veins.
They have thicker walls relative to the size of lumen.
They NEVER have valves.
They carry blood from capillaries to the heart.
They have a low pressure.
They have thinner walls relative to the lumen.
They may have valves. The veins that have to move blood against the force of gravity will have more valves than other veins. Some veins do not have any valves.
Describe the Types of Arteries
Elastic Arteries: Are the largest arteries, they contain elastic connective tissue which allows them to stretch when blood flow surges through them. The Ascending Aorta, the pulmonary trunk and it's immediate branches are examples. Elastic arteries need to squeeze blood along.
Muscular or Medium Arteries: These are the typically named arteries, they distribute blood flow to parts of the body. They have thick walls with smooth muscle and connective tissues.
Arterioles: These distribute blood within an organ or tissue. They have thinner walls with less smooth muscle and connective tissues than Medium arteries.
Capillaries: The primary site for gas exchange, very thin with no smooth muscle or connective tissues surrounding.
Describe the Types of Veins
Large Veins: These return blood to the heart. Primary examples are the Superior and Inferior Vena Cavae. Smooth muscle and connective tissue line these.
Medium Veins: Gather blood from areas of the body and move it to the large veins. Some smooth muscle and connective tissues line these.
Small Veins: These gather blood from tissues.
Venules: Gather blood from capillaries. Also some exchange of materials occurs here as well.
What is Arteriosclerosis?
Hardening of the Arteries
Buildup of Plaque in the Arteries.
What are the blood vessel pathway variations?
The Simple Pathway, Portal System, and Arteriovenous Anastomosis
Describe the Simple Pathway
Where there is one capillary bed between the arteries and the veins, this is very common.
Describe the Portal System
A system where there two capillary beds between arteries and veins. This is seen in two places in women and three in men.
In both men and women a portal system can be found in the Hepatic system where capillaries in the intestines pick up a substance (glucose for example) and then deliver that blood supply to capillaries in the liver for filtration.
There is also a portal system between the Hypothalamus and the Pituitary gland so that chemicals secreted by the hypothalamus are then moved to capillaries in the anterior portion of the pituitary gland to tell the pituitary gland what to secrete.
Between the capillary beds is a Portal vein.
The portal system seen only in males is in the male reproductive system.
Describe Arteriovenous Anastomosis
A blood vessel pathway where an artery by-passes a capillary bed and instead goes straight into the venous blood supply.
These are common in the skin where when the body needs to conserve heat will bypass the capillaries near the skins surface and keep blood deep within the sub dural layer.
Another situation is where multiple arteries and veins are connected to each other before and after capillary beds so that if blood supply is stopped at one artery it can still get to the capillary bed via another pathway. Similar on the venous side of the capillary. The arms have many arteries and veins connected like this so that if the radial artery is occluded for example the blood will flow through another artery to reach the capillaries of the hand.
At any given time where is the blood supply in the body?
70% is in the systemic circuit, 54% of it remains in the veins, they are larger in diameter and hold more blood. 11% remains in the arteries and 5% in the various capillaries.
18% remains in the pulmonary circuit and the remaining 12% is in the heart.
What is the endothelium?
The SIMPLE SQUAMOUS EPITHELIUM that lines the entire circulatory system, blood vessels and heart.
What are the layers of a capillary?
The Endothelium and the Basement membrane.
What are the layers of larger Arteries and Veins? Describe each layer.
The Tunica Interna, Tunic Media and Tunic Externa.
The Tunica Interna is the deepest layer, consisting of the Endothelium, the basement membrane and in some veins a valve.
The Tunica Media is the middle layer consisting of smooth muscle and some connective tissues.
The Tunica Externa is the most superficial layer consisting of a thicker connective tissue which provides strength to the vessel. The Vasa Vasorum is found in the Tunica Externa.
Describe the Vasa Vasorum
Its found in the Tunica Externa of larger vessels and is literally translated to the Vessel of the Vessels. The larger vessels need to supply the thicker walls with blood and they do this with vessels that run through the tunica media and externa.
What are Baroreceptors? Where are they found? What do they do?
They are pressure receptors found in some major blood vessels such as the Aorta on the Aortic Arch, the Carotid Sinus, Right Subclavian Artery and in the Kidneys.
The sensors in the vessels detect changes in pressure and alert the brain which makes changes to vasotone and heart rate to compensate for the needed increase or decrease in blood pressure.
Different neurons sense systolic and diastolic blood pressures.
Briefly explain what happens to blood supply and cardiac output during periods of rest verses periods of activity.
During periods of rest the cardiac output will drop to approx. 5liters/min and vessels carrying blood to the intestines, renal, digestive areas will dialate allowing more flow while vessels to the muscles will constrict and reduce flow.
During periods of activity the cardiac output will climb and blood flow to digestion centers will decrease allowing more blood to flow to the areas of skeletal muscle in use.
What is pulse pressure?
The difference between systolic blood pressure and diastolic blood pressure.