Circulatory System Flashcards
What is the content of the tunica intima.
These are layer(s) of endothelial cells that interact directly with the blood content. They’re stabilized by the basement membrane.
Describe the content of tunica externa.
This is a layer of structural protein such as collagen much like the basement membrane between the tunica intima and the tunica media. Unlike the basement membrane which acts like a scaffold only, the tunica externa is innervated by the ANS and responds accordingly.
Contrast the structures of veins from arteries.
While both share all 3 layers of a vessel: tunica intima, tunica media, and tunica externa, the veins do not have a larger tunica media seen in the arteries. This large layer in arteries have a large content of elastin or smooth muscle (depending on large/middle a. Or small a//arterioles respectively.) and veins have little of either in its tunica media. This causes the veins to have little recoil and allows it to act like a store of blood volume.
Both large/median size arteries and small a./arterioles have large tunica media. However, how are they different from one another?
Arteries large and middle - Their large tunica media is made of elastin mostly which helps maintain the high pressure and movement of blood through pathway
Small a./arterioles - have a high smooth m. content. Which allows the dilation or constriction of the vessels. (smooth m allows increase resistance)
What is the vaso vasorum. What is its significance in the aorta?
Vasa Vasorum - Little blood vessels on blood vessels. Therefore these feed the large vessels like the aorta.
Contrast the different volumes of blood present in the arterial and venous system.
Differences in volume. a. - low volume (15%) while v. - large volume system (65%)
Contrast the total volume of blood in the heart and capillaries
Both have the same content. 5% of the blood at any given time is in the heart, 5% in the capillaries
Contrast the different consequences seen with breakage of an arterial vessel vs breakage of a venous vessel.
Break in the arterial system - lead to a hemorrhage because it is such high pressure leading to increased volumes to leak out.
Break in Venous system - a pooling of blood like a bruise before the vessels clot off. This is due to the pressure system.
What is the importance of the tunica externa.
This is the most external layer from the lumen of the vessels. It consists of lots of collagen fibers which allows some strength to the blood vessels. The tunica externa also anchors the blood vessels to neighboring organs and tissues.
What characteristic of the circulatory system allows the continuation of high resistance to blood flow.
The high resistance is maintained by the Tunica Media - a layer of smooth muscle in arterioles and small arteries. As blood enters the vessel, it expands, however, the elastin proteins and the smooth m. cause the vessels to recoil back to its normal shape. This bouncing back to normal not only pushes the blood forward down the path, but also creates high resistance.
The lack of resistance seen in the venous system allows the venous system to carry how much of the total body’s blood content?
60 - 65% of blood
True or false: Blood flow through the venous system is due to the one way valve system.
False. The one way valve system prevents backflow of blood due to gravity. The movement of skeletal muscles helps blood flow up against gravity.
Mechanistically describe how valves within the venous system prevents backflow of blood.
These valves are a one way valve only. This means that they allow blood to flow up, however, as the blood backflows, the blood’s volume creates a pressure against the valves, closing them.
How are capillaries able to achieve the nutrient and waste exchange?
Capillaries are made of 2 endothelial cells forming a single cell layer around the lumen (the pathway of blood travel)
You manipulate the endothelial cells by adding a new alien protein that induces the cell membrane to engulf molecules from outside of the cell. Where in the circulatory system might this be useful? What is this process called?
This process is pinocytosis, a process in which some type of molecule approaches the membrane of a cell, and it consumes the nutrients within and keeps the nutrients in a vesicle within the cell until it can expel it or consume it. This is most important to be used at the capillary level where nutrient and waste exchange occurs.
You’re studying the flow of blood through the capillaries of a newborn baby. Since his birth, he’s experiencing deprivation of nutrients and you suspect this has to do with the exchange at the tissues. You find that the capillaries are only exchanging nutrients through the membrane of endothelial cells and through pinocytosis only. What else should also be occurring?
Within the single cell layer created by 2 cells, there are different types of junctions - Via intracellular cleft and Fenestration - both allow the movement of nutrients from one side to the other. Hydrostatic pressure expands the holes and pushes molecules across
Explain how decreasing the radius of a vessel affects the resistance against the fluid flow.
Dr. Jean Louis Marie Poiseuille => R = 8Lη/πr^4
R is inproportionally equal to R = 1/r^4. Therefore the as the radius decreases, the resistance of the tube increases. The power of 4, entails that changes with a radius will affect the resistance by 16!
Where in the circulatory system can the most resistance be produced in blood flow?
Arterioles - covered with smooth muscles. When The smooth m. is relaxed, the tube is completely dilated. With smooth m. contracting, the arterioles is very constricted. This then increases the resistance of the tube while decreasing the radius
In Mark, blood is flowing through a healthy artery with a radius of 2 cm. However, in Jessica’s arteries are occluded by 20%,reducing the radius of her artery to 1 cm. But the same length as Mark’s. How much higher is the resistance of Jessica’s blood compared to Mark’s?
A. 2x greater
B. 4x greater
C. 8x greater
D. 16x greater
D. 16x greater Pouseille’s law -> R = 88Lη/πr^4 isolate other nonessential variables.
R ∝ 1/r^4 R ∝1/r^4
R ∝ 1/2^4 R ∝1/1^4
R ∝ 1/16 R ∝ 1
Therefore there is a difference in 16 factors, 1:16
True or False: There is a sharp decrease in blood velocity seen from arterioles to capillaries in order to achieve the slowed flow of blood for blood exchange.
False. The sharp drop in blood pressure is seen in arterioles. Because arterioles have a high area to volume ratio, therefore the volume that travels through the arterioles interact much more with the surface area of the arterioles. This leads to more resistance.
This increase in resistance decreases the pressure and the velocity of the blood as well
Why is the slowed blood flow from arteries to arterioles beneficial?
In the capillaries. Arterioles connected to capillaries. Capillaries are very thin (single cell layer) they are not built to withstand high pressures like arteries.
Exchange also takes place here. Therefore for exchange to occur efficiently and effectively, need the speed to also be slow as well
Based on the continuity equation, how does this explain the low velocity of blood flow seen in capillaries?
Continuity Equation Q = A1v1 = A2V2; Q - The flow rate of , this does not change because the circulatory system is a closed system
The cross sectional area of all the capillaries in the body are much greater than the cross section area in the arteries. Therefore this supports the slow velocity seen in the capillaries
This explains why the resistance in the arterioles is so great. This lowers the pressure and the velocity of the blood flow, allowing blood to reach the right velocity before the capillaries to prevent damage to the capillaries
As blood enters the venules into the venous system, the pressure of the blood and the velocity of the blood is fairly low for both. What is contributing to both of these physical quantities?
(1) Blood flow has to travel against gravity
(2) The tunica media layer of the venous vessels are thin and lack elastin. This causes the vessels to not have the ability to recoil, therefore no increase in pressure seen here. Lack of recoil leads to increase volume of blood as well, leading to decrease pressure too
How do you measure blood pressure?
(1) calculating pressure in aorta during systole (when left ventricles contract) - 120mmHg
(2) Calculating Pressure in Left ventricle relaxation when the left atrium fills the ventricles - 80 mmHg
Pressure - systole/diastole
