Cardiovascular Physiology
Lecture 1 objectives
Explain the basic anatomy of the heart and its arrangement into 4 chambers.
Appreciate that blood flows in series through the systemic and pulmonary circulations.
Explain what causes fluid to flow through a tube.
Understand the relationship between blood flow, pressure and resistance
Appreciate the three factors that influence the resistance to flow through a tube.
Introduction
The primary function of the cardiovascular system is to deliver blood to tissues, and remove waste from cells.
The heart acts as a pump to carry blood containing oxygen to the tissues, and the vessels consist of arteries and arterioles, carry a small percentage of this blood.
The veins carry the majority of blood at any one time, and the thin capillaries are located between arteries and veins, and here is where nutrients, wastes and fluid are exchange.
Homeostatic functions of the cardiovascular system includes regulation of arterial blood pressure, delivery of hormones, and various adjustments required to respond to
haemorrhage, exercise, and changes in posture.
Circuitry of the cardiovascular system
Each side of the heart has two chambers, a ventricle and an atrium, which are connected by atrioventricular valves. AV valves ensure a one-way flow of blood from the atrium to the ventricle.
Left heart is connected to the systematic circulation, which encompasses the systematic arteries, capillaries and veins. System circulation involves the pumping of blood from the left ventricle of the heart to all organs of the body except the lungs.
Right heart is connected to the pulmonary circulation, where the right ventricle pumps deoxygenated blood to the lungs.
Both the left and right heart function in series so the blood is pumped sequentially from the left heart to the systemic circulation, to the right heart, to the pulmonary circulation, to the left heart again.
Cardiac output – the rate at which blood is pumped from either ventricle. Because the left and right side of the heart work in series, the cardiac output of the left ventricle is equal to the cardiac output of the right ventricle, in the steady state.
Venous return – the rate at which blood is returned from the veins to the atria. Because the left and right heart operate in series, the venous return to the left heart is equal to the venous return to the left atrium, in the steady state.
CO = VR – the cardiac output from the heart equals the venous return to the heart, in the steady state.
Blood vessels:
1. Closed system of passive conduits
2. Deliver blood to and from tissues where nutrients and wastes are exchanged 3. Regulate blood flow to organs: when resistance alters, blood flow to organ alters
