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
