Bio 436 Lecture 8

Vasodilation

Decreases resistance, increases blood flow. Relaxation of smooth muscle of the blood vessel and causes an increase in the blood vessel radius.

Bicuspid/mitral valve

Left AV valve. Two cusps.

Venous return

The rate of blood flow back to the heart. It normally limits cardiac output

End diastolic volume (EDV)

Volume of blood in ventricles at end of diastole, just before cardiac contraction

End systolic volume (ESV)

Volume remaining in the ventricle after contraction

Pulmonary vein

A vein carrying oxygenated blood from the lungs to the left atrium of the heart

Stroke volume (SV)

Amount of blood pumped by each ventricle with each heartbeat, averaging 70 ml per beat in the adult at rest. Volume ejected by a single ventricular contraction. Blood ejected by the heart. Determined by 3 variables: EDV, TPR (Total Peripheral Resistance), Contractility - strength of ventricular contraction (increased by sympathetic activity) SV = EDV - ESV

Isovolumetric relaxation

An interval in the cardiac cycle, from the aortic component of the second heart sound, that is, closure of the aortic valve, to onset of filling by opening of the mitral valve. It can be used as an indicator of diastolic dysfunction

Arteriosclerosis

Arteries cannot expand and therefore create more resistance and higher pressures. Lost elasticity.

Skeletal muscle pump

Blood is moved toward heart by contraction of surrounding skeletal muscles, pressure drops in chest during breathing

Cardiac Output (CO)

CO = HR x SV CARDIAC OUTPUT is the amount of blood pumped out by each ventricle in one minute. Cardiac output is directly related to heart rate and stroke volume. Blood flow. HEART RATE (HR) is the number of times the heart beats in one minute, averaging 70-75 beats per minute (bpm) in the adult at rest. STROKE VOLUME (SV) is the amount of blood pumped by each ventricle with each heartbeat, averaging 70 ml per beat in the adult at rest.

Vasoconstriction

Caused by sympathetic nervous system, increases resistance, decreases blood flow. Contraction of smooth muscle of the blood vessel. Decreases blood vessel radius.

Poiseuille's Law

Describes factors affecting blood flow and describes the relationship between blood pressure, vessel radius, vessel length, and blood viscosity on laminar blood flow. (πΔPr4)/(8Lη)

Vascular resistance

Determines how much blood flows through a tissue or organ

Ventricular ejection

Ejection of blood from ventricles of heart.

Total peripheral resistance (TPR)

Impedance to blood flow in arteries. Blood cells and plasma encounter resistance when they contact blood vessel walls. If resistance increases, then more pressure is needed to keep blood moving. Main sources: Vessel diameter, blood viscosity, total vessel length

Isovolumetric contraction

In early systole, during which the ventricles contract with no corresponding volume change. This short-lasting event takes place when both the AV valve and SL valve are closed.

Myocardium

Muscular tissue of the heart

Pulse pressure (PP)

PP = systolic pressure - diastolic pressure

Atherosclerosis

Plaques in arteries that increase resistance, decrease flow rate, type of arteriosclerosis, leads to heart disease.

Semilunar valve

Pulmonary and Aortic. At bases of aorta and pulmonary artery consisting of three cusps that prevent flow of blood back into the heart.

Ventricular systole

Pumps blood out. Contraction of the heart. 60% of the blood contained within the heart is ejected from the heart.

Tricuspid valve

Right AV valve. Prevent back flow of blood into right atrium. Three cusps.

Mean arterial pressure (MAP)

Significant because it is the difference between the arterial and the venous pressure that drives blood through the capillary beds of our organs. MAP = Diastolic pressure + 1/3 Pulse Pressure (PP)

Pulmonary artery

The artery carrying blood from the right ventricle of the heart to the lungs for oxygenation

Resistance vessels

The blood vessels, including small arteries, arterioles, and metarterioles that form the major part of the total peripheral resistance to blood flow.

Cardiac cycle

The more blood that returns to the ventricles will result in more blood being pumped out of the ventricles. This is because, as more blood fills the ventricles, it stretches the heart muscle, stretching the sarcomeres of the myocytes a little more. This gives the sarcomeres more separation at rest and therefore more ability to overlap when they contract, producing a stronger contraction and more ejection of blood.

Frank-Starling law of the heart

The more blood that returns to the ventricles will result in more blood being pumped out of the ventricles. This is because, as more blood fills the ventricles, it stretches the heart muscle, stretching the sarcomeres of the myocytes a little more. This gives the sarcomeres more separation at rest and therefore more ability to overlap when they contract, producing a stronger contraction and more ejection of blood.

Capacitance vessels

Veins that hold most of blood in body (70%) Have thin walls & stretch easily to accommodate more blood without increased pressure (higher compliance) - only 0-10 mmHg