Exercise 5 Cardiovascular Dynamics

34. Why are arteries sometimes called the resistance vessels? More pressure is required to push blood through a constricted vessel than through a dilated one. The force opposing blood flow is called resistance (R) , and arterioles are therefore called resistance vessels

There are three main types of blood vessels: arteries, veins, and capillaries. Arteries are vessels that usually carry highly oxygenated blood away from the heart and to the rest of the body. (The pulmonary trunk and related arteries are exceptions, as they actually carry blood from the lungs toward the heart.) Because arteries must transport high volumes of blood being forcefully pumped out by the heart and must therefore withstand greater pressure, most have thick, muscular walls and are more flexible as well. Arterioles, smaller types of arteries with thinner walls, branch off of the arteries to carry blood to another type of vessel, called the capillary. Capillaries are the most abundant blood vessels in the body. Thinner and smaller than the other blood vessels, the role of capillaries is to exchange substances like water, gases, chemicals, nutrients, wastes, etc. with the tissues of the body. The third type of blood vessel is the vein. Although they are generally larger than the other blood vessels, veins tend to have thinner, less flexible walls, as they are not forced to deal with such high blood pressures. Venules (veins’ versions of arteries’ arterioles) connect the capillaries to the veins, which then transport blood back

Deacreased vascular resistance and increased arterial pressure causes an increase in blood flow. This is important to supply organs with oxygen. 4. Restate your predictions that were correct and give data from your experiment that support them. Restate your predictions that were not correct and correct them with supporting data from your experiment. MAP would increase due to increase in activity, SVR would decrease due to decrease in resistance, CO would increase due to more force of blood being expelled.

If the resistance increases, cardiac output decreases and the blood pressure increase and if the resistance decreases, cardiac output increase and the blood pressure decreases. During each contraction, the amount of blood pumped out by one ventricle is stroke volume. The number of heartbeat in each minute is known as heart rate. The normal heart rate value for adult is 60-100 beats per minute. The cardiac output is directly proportional to the stroke volume and heart rate. The average arterial pressure during one cardiac cycle is mean arterial pressure (MAP), which is directly related to the cardiac output and resistance. The instrument sphygmomanometer with an air cuff attached to the reservoir is used to detect blood pressure associated with the pulse.

A number of factors oppose this force such as, "a raised intracranial pressure, increased blood viscosity, and narrowing of the vascular diameter." Cerebral blood flow is relatively unchanged even with such opposing forces. This involves a special autoregulatory response. When arterial blood pressure drops, then the cerebral vascular resistance also is lowered. The opposite is also true to prevent a drastic increase in pressure within the cerebral vasculature. However, this autoregulatory system breaks down when the pressure falls very low.

Shearing forces acting on the vascular endothelium generated by blood flow causes a release of calcium and subsequent cNOS (cyclic nitric oxide synthase) activation. Therefore, increases in blood flow stimulate NO formation (flow-dependent NO formation). Nitric oxide then causes independent vasodilation by inhibiting vasoconstrictor influences of phenylephrine and alters its potency and contractile effect. (Richard E. Klabunde. 2010)

We expect to see different patterns of pressure-diameter (dP/dR) relationship with similar trends to those obtained in the ex vivo experiments as a result of dynamic smooth muscle contractile activity during pulse pressure waves. C) THE EXPERIMENTAL CONDITIONS AND PROPOSED EXPERIMENTS 1. Ex vivo isolated system: (Wire myography and pressured myography) The following parameters will be determined in three different conditions, with various reagents being added, in both control and MFS aortic samples ex

Chronic responses to the cardiovascular system: Increase in stroke volume: When the size of the heart increases, the blood capacity inside the heart also increases because it stores more blood. This means that the stroke volume can increase. Increase in cardiac output: Cardiac output is the amount of blood pumped by each ventricle per minute. Cardiac output increases 5 to 7 times which means more oxygen can get to the muscles. The bigger the cardiac output depends on how much the stroke volume and heart rate increases.

has to work harder pumping blood to the rest of the body. Blood in our

In the first part of the practical, we will dissect the heart of a sheep and observe its anatomical structure. We will also examine the structure of blood vessels at a microscopic level. My hypothesis is that by examining the anatomy of the cardiovascular system, we will be able to detect differences in both vessels and the chambers of the heart. In the second part of the practical we will examine the electrical activity of the heart. In doing so my aim will be to produce a familiar ECG reading containing a P wave, QRS complex and T wave. Futhermore, we will take blood pressure readings by listening to the korotkoff sounds of the heart using a sphygmomanometer and stethoscope. We hypothesis that the higher the arm position is from the ground, the smaller the blood pressure reading will

This allows your cardiovascular centres in your brain a little bit more latitude as far as controlling your heart rate. If you were to remove a beating heart from someone's body you would find that the heart is no longer being suppressed by the parasympathetic nervous system and it will accelerate to the same pace as the sinoatrial node. The SA node generates action potentials approximately 100 times per minute due to the physiology of the heart, its own permeability to sodium and calcium via its channels, and a host of other things. Anywhere between 80 to 100 beats per minute is normal for the SA node.

Basically, arterial blood pressure (BP) is directly proportional to the product of blood flow (cardiac output, CO) and the resistance to passage of blood through pre-capillary arterioles (peripheral vascular resistance, PVR) Hypertension can be caused by either an increase in Cardiac Output (CO) or by an increase in Peripheral Resistance (PR)

Heart Contractions and Blood Flow – An animation of the showing how the heart pumps.

reports the amount of force exerted by the blood into the arteries during ventricular contraction.

In physics, work output is calculated by multiplying force applied by the displacement caused. However, the cardiac output is got by multiplying the heart rate by the volume of the stroke. The cardiac output is determined by the strength of contraction and also by the resistance of the peripheral flow. The stroke volume of a typical adult is 80ml. it also takes about one minute for the average red blood cell to make one complete cycle of the entire body. The maximum cardiac