The Circulatory System Functions of the Circulatory System: To remove waste products of cell metabolism To circulate necessary materials to all cells (e.g. oxygen, hormones, nutrients) To regulate temperatures in various parts of the body

Composition of Blood

Plasma: water: to dissolve minerals and ions and to allow contents of blood to flow plasma proteins: antibodies for defense against bacteria and viruses solutes: ions and minerals needed elsewhere in the body and also to maintain isotonic nature of blood the liquid portion of blood

Red Blood Cells (Erythrocytes)

White Blood Cells (Leucocytes)

Platelets

Blood Vessels Arteries and arterioles: carry blood away from the heart walls contain a thick muscle layer that help control the flow of blood and enables them to withstand high pressures

Veins and venules: carry blood towards the heart walls have thinner muscle layer and can stretch more easily; cannot carry blood at high pressures contain sets of one-way valves to prevent the backflow of blood

The Structure of an Artery vs. a Vein

The Function of Venous Valves

Capillaries: the smallest blood vessels which connect arterioles as and venules capillaries have thin permeable walls (one cell thick) gas exchange (diffusion of oxygen into cells and carbon dioxide out of cells) occurs at capillaries

Internal Respiration (gas exchange at the capillaries)

Circulation Pulmonary circulation: supply of blood to the lungs Cardiac circulation: supply of blood to the heart muscle Systemic circulation: supply of blood to all other tissues of the body

A B C D EF-1 G H I J K L M N P O F-2 A. right atrium B. right ventricle C. left atrium D. left ventricle E. aorta F-1. superior vena cava F-2 inferior vena cava G. pulmonary artery H. pulmonary vein I. pulmonary semi- lunar valve J. tricuspid valve K. mitral valve L. aortic semi-lunar valve M. sino-atrial [SA] node N. AV node O. Bundle of His P. Purkinje fibres

The Heart  is a muscle that supplies the pressure to move the blood through the arteries  is made of cardiac muscle tissue  is covered with a sac of epithelial and fibrous tissue called the pericardium that contains liquid which reduces friction as the heart beats

1. the heart consists of two pumps, separated by a muscular wall called the septum that prevents the mixing of blood from the two sides 2. the two pumps in the heart each have two chambers: the atrium (on top), and the ventricle (on the bottom) 3. an atrioventricular valve [bicuspid or tricuspid] controls the flow of blood between the atrium and the ventricle 4. the pulmonary semi-lunar valve and the aortic semi-lunar valve prevent backflow from the arteries leaving the heart

5. The veins [vena cava or pulmonary] bring blood to the heart 6. The arteries [aorta or pulmonary] take blood away from the heart

B. Heart Beats  the pacemaker (sinoatrial node) is a group of nerve fibers in the right atrium that maintain the beating of the heart 2. the SA node sends a signal that causes the atria to contract from the top and force blood through the atrioventricular valves 3. The signal also reaches the AV node which reacts by sending a signal down the Bundle of His to the bottom of the ventricles. 4.The Purkinje Fibres in the ventricle transmit this signal to start the ventricular contraction from the bottom and this forces blood out the aorta or pulmonary arteries

5. one heart beat = one cardiac cycle 6. each cardiac cycle consists of a systole (a contraction of the heart muscle) and a diastole (a relaxation of the heart muscle) 7. the sounds you hear when your heart beats are the sounds of the valves in your heart closing (first the atrioventricular valves (bicuspid and tricuspid), then the semi-lunar valves)

Right Side The full atrium triggers the SA node which causes both the atria to contract Low O 2 blood enters the right atrium from the superior or inferior vena cava Blood is forced through the tricuspid valve into the ventricle The ventricle fills and the electrical signal triggers the AV node to send a signal down the Bundle of His The Purkinje Fibres distribute the signal and the ventricle contracts Blood is forced past the pulmonary semi-lunar valve and into the pulmonary artery

Left Side The full atrium triggers the SA node which causes both the atria to contract High O 2 blood enters the left atrium from the pulmonary vein Blood is forced through the bicuspid valve into the ventricle The ventricle fills and the electrical signal triggers the AV node to send a signal down the Bundle of His The Purkinje Fibres distribute the signal and the ventricle contracts Blood is forced past the aortic semi-lunar valve and into the aorta

Blood flow through Arterial and Venous vessels, respectively

Problems in Circulation: work on these questions now!