The Cardiovascular System

The Cardiovascular System A closed system of the heart and blood vessels The heart pumps blood Blood vessels allow blood to circulate to all parts of the body The cardiovascular system delivers oxygen and nutrients to cells and removes carbon dioxide and other waste products

The Heart Location: Bony thorax between the lungs Pointed apex directed toward left hip About the size of your fist Heart is covered by a double membrane called the Pericardium Serous fluid fills the space between the layers of pericardium to prevent friction when heart contracts

The Heart Figure 11.1

The Heart: Chambers Right and left side act as separate pumps Four chambers Atria (receiving chambers) Right atrium Left atrium Ventricles (pumping chambers)) Right ventricle Left ventricle Figure 11.2c

The Heart: Valves Valves allow blood to flow in only one direction Four valves: Atrioventricular valves between atria & ventricles Bicuspid valve (left side) Tricuspid valve (right side) Semilunar valves between ventricle & artery Pulmonary semilunar valve Aortic semilunar valve

Blood Vessels: The Vascular System Taking blood to the tissues and back Arteries: carry blood AWAY from heart Veins: carry blood back to heart Capillaries: small blood vessels Figure 11.8a

Blood Circulation Figure 11.3

The Heart Heart valves open and close as blood pumps through. Valves prevent backflow of blood. Valves are held in place by chordae tendineae (“heart strings”) Heart muscle cells contract, without nerve impulses, in a regular, continuous way through electrical impulses – Sinoatrial node Pacemaker Atrioventricular node

The Heart: Associated Great Vessels Vena cava (large veins) Enters right atrium with oxygen poor blood Pulmonary (lung) arteries Leaves right ventricle with oxygen poor blood sent to lungs to pick up more oxygen Pulmonary veins (four) Enter left atrium with oxygen rich blood Aorta Largest artery, leaves left ventricle with oxygen rich blood for body tissues

Filling of Heart Chambers – the Cardiac Cycle Right and left atria contract simultaneously; Atria relax, then ventricles contract Figure 11.6

The Heart: Regulation of Heart Rate Increase heart rate: Sympathetic nervous system (stress, crisis, BP) Hormones (Epinephrine, Thyroxine) Exercise, Decreased blood volume Decreased heart rate: Parasympathetic nervous system High blood pressure or blood volume Dereased venous return

Major Arteries of Systemic Circulation Figure 11.11

Major Veins of Systemic Circulation Figure 11.12

Pulse Pulse – pressure wave of blood Monitored at “pressure points” where pulse is easily palpated Figure 11.16

Variations in Blood Pressure Normal Blood Pressure 140–110 mm Hg systolic 80–75 mm Hg diastolic Hypotension (low blood pressure) Low systolic (below 110 mm HG) Often associated with illness Hypertension (high blood pressure) High systolic (above 140 mm HG) Can be dangerous if it is chronic

Anatomy Heart Beat – Lub Dub Lub (closing of atrioventricular valves) Dub (closing of pulmonary lunar valves) Illness/Issues of the Heart (Cardiovascular Sys) Atherosclerosis: lipid (fat) deposits on arteries Angina Pectoris: crushing chest pain, lack of oxygen to heart Myocardial Infarction: heart attack, lack of oxygen to myocardium (heart muscle) can’t pump Tachycardia: Rapid heart beat, over 100 beats Bradycardia: Slowed heart beat, under 60 beats

TEST CH 11 – TOMORROW, Pencil! Anatomy TEST CH 11 – TOMORROW, Pencil! In Text book p 386, Do Short Answer: 1, 3, 4, 5, 6, 7, 12, 13, 16, 17, 18, 19, 23, 30 DUE TODAY– Turn in end of class