The Cardiorespiratory System Notes adapted from Exercise Science and Foundations of Human Movement

Components of the Cardiovascular System Heart – size of closed fist Blood – RBC, WBC, plasma Blood vessels – arteries, veins, capillaries Lungs

The Primary Roles of the Cardiovascular System 1. To transport oxygen from the lungs to the tissues and to transport carbon dioxide from the tissues to the lungs 2. To transport nutrients from the digestive system to other areas in the body and transport waste products from sites of production to sites of excretion. 3. Maintain body temperature (thermoregulation) 4. Prevent infections (immune system)

The Heart’s Linings Myocardium  is term used to describe cardiac tissue Pericardium  sac filled with fluid to reduce friction Epicardium  outer lining of heart that lies against pericardium Endocardium  lines the inside of the heart

The Heart Structure comprised of cardiac muscle that serves to pump blood through the human body. consists of four chambers: - two ventricles (left and right)  pump blood through the body, - two atria (left and right)  receive blood from peripheral organs and pump blood into the ventricles Left ventricle  pumps blood through the entire body (are larger and with stronger muscle walls than the right ventricles) Right ventricle  pumps blood a short distance to the lungs

Chambers of the Heart Two Atria –Right atrium gets deoxygenated blood from the superior and inferior vena cava –Left atrium gets oxygenated blood from pulmonary veins Two Ventricles –Left has thicker wall and pumps to the body –Right pumps blood to lungs to get oxygenated –Separated by interventricular septum

The Four Valves of the Heart Valves prevent the backflow of blood. Atrioventricular valves (gateway to ventricles) –Right = tricuspid –Left = bicuspid/mitral –Valves attach to special muscular extensions of ventricle walls – PAPILLARY MUSCLE – by strands of strong specialized tissue called CHORDAE TENDINAE Semilunar valves (gateway to lungs and aorta) –Pulmonary and aortic

Structures of the Heart Right Side Superior and inferior vena cava Right atrium Right ventricle Pulmonary artery Tricuspid valve Pulmonary valve Left Side Aorta and thoracic (descending) aorta Left atrium Left ventricle Pulmonary vein Bicuspid (mitral) valve Aortic valve Common structures of both: chordae tendinae, papillary muscles, and the interventricular septum

Internal Structures of the Heart

The Heart Pathway of blood flow: RIGHT ATRIUM Tricuspid valve RIGHT VENTRICLE Pulmonary semilunar valve Pulmonary arteries Lungs Pulmonary veins LEFT ATRIUM Bicuspid valve LEFT VENTRICLE Aortic semilunar valve Aorta Inferior vena cavaSuperior vena cava Arteries Capillaries Veins Deoxygenated Oxygenated

The Heart Function The heart contracts in a constant rhythm that may speed up or slow down depending on the need for blood (and oxygen) in the body. The beating of the heart is governed by an automatic electrical impulse generated by the sinus node (sinoatrial node) The sinus node is a small bundle of nerve fibers that are found in the wall of the right atrium The sinus node generates an electrical charge called an action potential. The action potential causes the muscle walls of the heart to contract. This action potential travels through the two atria and the two ventricles via the a-v node and the Purkinje fibres. The atria contract before the ventricles contract, which allows for the blood to be quickly pumped into the ventricles from the atria

Excitation of the Heart The heart conduction system includes: –Sinoatrial (SA) node –Internodal pathways –Atrioventricular (AV) node –Bundle of HIS –Right and left bundle branches –Purkinje fibres

Electrical Conduction System of the Heart

The Heart Blood Pressure This is an important measure of cardiac function. There are two components to the measure of blood pressure: 1.Diastole - It is used to describe the pressure in the heart when the ventricles are relaxed and are being filled with blood. Indicator of peripheral blood pressure (the blood pressure in the body outside the heart). 2.Systole - It is the pressure in the ventricles when they are contracting and pushing blood out into the body. FYI: The normal range of pressure in the atria during diastole is about 80 mmHg, and during systole is about 120 mmHg.

Systole and Diastole Cardiac cycle  the series of events that occur through one heart beat –Systole when ventricles contract (heart empties) –Diastole when ventricles relax (heart fills) Heart sounds heard through a stethoscope –Lub - closing of the atrioventricular valves –Dup - closing of the semilunar valves

The Finely Tuned Cardiac Cycle (a) As the heart relaxes in diastole, both atria simultaneously fill with blood. (b) The mitral (bicuspid) and tricuspid valves open, and the atria, squeezing into systole, force blood into the ventricles. (c) As the ventricle compartments fill with blood, they contract, thereby ejecting blood to the lungs and body. (d) The atria again relax and refill with blood.

Electrocardiogram

Coronary Circulation Right and left coronary arteries nourish the myocardium Left and right cardiac veins remove waste from the myocardium

The Vascular System Venules and Veins –Carries blood towards the heart –Usually carries deoxygenated blood except for the pulmonary vein –Major properties limited contractibility and elasticity One-way valves (varicose veins) Arteries and Arterioles –Carries blood away from the heart –Usually carries oxygenated blood except for the pulmonary artery –Thick smooth muscle wall –Major properties Contractibility Elasticity

The Vascular System Capillaries –Permit exchange of nutrients and gases; walls are one cell thick –Capillaries connect arterioles and venules

Skeletal Muscle Pump Bringing Blood Back to the Heart Three main ways: –Thoracic pump –Venoconstriction –Skeletal muscle pump muscle contraction one-way valves

Properties of Blood Erythrocytes - Red blood cells Leukocytes - White blood cells Plasma Thrombocytes - Platelets Color (hemoglobin) –Arterial (red blood) –Venous (blue blood) Volume

The Role of Erythrocytes (Red Blood Cells) Carry oxygen Carry oxygen Carry carbon dioxide Carry carbon dioxide Carry nutrients Carry nutrients Remove waste Remove waste

Characteristics of Erythrocytes (Red Blood Cells - RBC) Made in bone marrow Hemoglobin is a specialized protein located on the RBC Transport nutrients and waste

Characteristics of Leukocytes (White Blood Cells) Destroy foreign elements Critical in the function of the immune system Help in the healing of bone and multiple other cellular activity

Characteristics of Plasma Fluid component of blood Transport medium mostly water Makes up 55 percent of blood Other dissolved substances in plasma –Gases –Nutrients (protein) –Ions (electrolytes)