Question

1) Explain the difference in the functions of low-density lipoproteins and high-density lipoproteins and explain why one is called “good” cholesterol and the other is called “bad” cholesterol.

2) Define vasoconstriction and vasodilation. What is the mechanism of regulation?

3) The heart is called a "double pump" because there are two functionally separate circulations. Trace the pathway of each of these circulations and include the following information: heart chambers involved, major blood vessels involved, and general areas through which the blood flows. Begin with the right atrium.

Answer 1

1.LDL(Low Density Lipoporoteins) are formed in the liver , when triglycerides are removed from VLDL by the lipoprotein lipase enzyme (fewer fat molecules with same protein transport shell), containing a higher proportion of cholesterol esters.They carry CHolesterol into Blood stream and Ends in the Arteries.

LDL are called Bad Cholesterol because,They carry cholestrol synthesized in the liver into BLood stream--------Build up of cholesterol in Arteries----- They stick to Blood vessels----predisposes to Diseases like Atherosclerosis,Myocardial Infarction etc.

HDL (high-density lipoprotein), absorbs cholesterol from the peripheral tissues including arteries-------- carries it back to liver.----------- liver flushes this cholestrol from the body------------So, High levels of HDL cholesterol can lower risk for heart disease and stroke------Hence they Are called Good Cholesterol.

2.

Vasoconstriction:Narrowing of the blood vessels Due to contraction of the muscular wall of the vessels.

Vasodialation:Widening of blood vessels,due to relaxation of smooth muscle cells within the vessels.

Vasoconstriction and Vasodialation are controlled by Autonomic Nervous System-Mailnly Sympathetic System.

Factors that triggers Vasoconstriction-

1.Exogenous Factors-

a)Ambient Temperature

2.Endogenous Factors-

a)ANS-Sympathetic stimulation

b)Endocrine Factors.

Factors That triggers Vasodialation-

1. Low oxygen levels

2.Reduced availability of nutrients,

3.Increase in temperature.

Right atrium-Right Atrioventricular Valve(Tricuspid Valve)-Right Ventricle-Pulmonary Valve-Pulmonary Artery----Lung (Where Oxygenation of Blood Occur)-Pulmonary Vein-Left Atrium-Left atrioventricular Valve(Mitral Valve)-Left Ventricle-Aortic Valve-Aorta-Aortic Branches to All parts of the Body.

From Upper Half Of the Body- Superior Venacava & From Lower Half of the Body -Inferior Venacava collects deoxygentaed Blood and Drains into Right Atrium