1. Why is it important that large arteries and veins be able to change diameter?
ID: 3512307 • Letter: 1
Question
1. Why is it important that large arteries and veins be able to change diameter? Which of these two vessels is responsible for maintaining relatively constant pressure in our vessels during ventricular diastole?
a. Would you want to promote or inhibit angiogenesis to treat A. cancer and B. heart disease? Explain why.
b. Describe four factors that influence mean arterial blood pressure.
c. Blood slows to a very low velocity in the capillary beds. Why does this happen (in terms of physics) and what does this low velocity flow allow to happen in the capillary beds?
Explanation / Answer
Arteries provide blood from heart to rest of the body. Due to this the blood needs to flow at a high pressure to reach every cell as fast as possible. This is why arteries have a small diameter compared to the veins. Arteries are surrounded by a thick muscular layer to modify their diameter. Ventricular diastole is the period during whichthe ventricles are filling and rlaxing. Arteries maintains relatively constant pressure during ventricular diastole.
a) Angiogenesis is the formation of new blood vessels in place of preexisting blood vessels. In the heart diseases, angiogenesis is the body's response to blockd arteries by creating new blood vessels to bypass the blockage and restore blood flow down stream to the affected area. Angiogenesis is also used by tumors to recruit new blood vessels to grow cancer cells by supplying nutrients and oxygen. Hence angiogenesis inhibitors are used in cancer to destroy the cancer cells. But it is not effective as there are many side effects due to angiogenesis inhibitors.
b) MAP is an average blood pressure in an individual during one cardiac cycle. It is influenced by following factors,
1. pheripheral resistance
2. blood volume
3. cardiac output
4.heart rate
Increase in the above factors increases the Mean arterial blood pressure where as decrease in the the above factors decreases the mean arterial blood pressure.
c) The velocity of blood flow is inversely proportional to the total cross sectional area of the blood vessels. As the total cross sectional area of the vessel increases, the velocity of flow decrases. In terms of physics continuity equation is followed, which involves
v=Q/A,
where v is velocity, Q is blood flow, A is the cross sectional area
since capillaries have the highest total croos sectional area, the slowest blood velocity occurs in the capillaries that allows time for capillaries to exchange gases and nutrients.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.