The heart & blood

Cardiovascular System Blood Heart Blood vessels Arteries - bring blood away from heart Veins – bring blood to heart Capillaries – smallest vessels where oxygen/nutrient exchange occurs

Heart Wall Located in the mediastinum within the thoracic cavity (pericardial cavity) Protected by serous membrane called pericardium Epicardium – forms outermost layer of cardiac wall Myocardium – composed of cardiocytes Endocardium – thin layer that covers chambers of heart

External Anatomy of the Heart Four chambers  2 ventricles , 2 atria Atria: “receiving” chambers and return blood from veins Ventricles: “pumping” chambers and distribute blood to lungs and tissues Pulmonary circuits  directs deoxygenated blood to lungs Systemic circuit  takes oxygenated blood to the body

Brachiocephalic Carotid Subclavian Vena Cava Aorta Pulmonary Arteries Pulmonary Trunk Pulmonary Veins Left Atrium Semilunar Valves & Aortic Valve Right Atrium Bicuspid/Mitral Valve Tricuspid/AV Valve Left Ventricle Right Ventricle

Coronary Circulation The heart can NEVER completely rest It needs to nourish itself Systemic circulation  coronary circulation: supplies myocardium with oxygen for muscle contraction

Left Coronary Artery Right Coronary Artery Circumflex Artery Marginal Artery Anterior IV Branch Posterior IV Branch

Coronary Circulation cont’d The arteries are circulating oxygenated blood Cardiac veins collect the deoxygenated blood from myocardium Veins merge at the coronary sinus Empties deoxygenated blood into the right atrium

How can the heart contract? Cardiac muscle tissue is “autorhythmic” Does NOT need stimulation from nerves Brain only dictates how fast the heart contracts Pacemaker  Sinoatrial node (SA node) Sets the pace by sending an electrical impulse to other nodal cells SA Node AV Node

Composition and Function Regulates pH and electrolyte levels Supplies cells with nutrients and oxygen Manufacture substances needed for defense against bacteria Ability to change from liquid to gel in clot formation for injury repair Classified into: Formed elements Plasma

Formed Elements Red blood cells (erythrocytes)  oxygen transport via hemoglobin White blood cells (leukocytes)  phagocytes, scavenger cells that destroy foreign substances Eosinophils Basophils – release histamine Platelets  injury mediators / blood clotting Normal bleeding time 0-7 min

Hematocrit Equivalent to the RBC concentration in the blood Used to determine possible anemia Can you still be anemic with a normal RBC concentration? Yes

Hemoglobin RBC protein responsible for oxygen transport Measuring the hemoglobin can give you information on oxygen carrying capacity of the blood

Cholesterol is carried in the blood Atherosclerosis: disease in which blood vessels become increasingly occluded or blocked by plaques High cholesterol levels can lead to atherosclerosis Normal value: is 130-200 mg per 100 ml of blood Good vs Bad Cholesterol HDL vs LDL

How does high cholesterol affect the heart?

Blood Pressure Pressure of the circulating blood against your vessel walls Systolic – when heart contracts and pushes through arteries Diastolic – measures pressure when ventricles are filling up / in between beats Normal is about 120/80 Hypertension  silent killer

Blood Typing – ABO & RH Blood type is genetically inherited Based on the type of antigen marker molecules on surface of blood cells Rh surface antigen (D antigen)  some people have it, some do not

RhoGAM

Due next week Chapter 29 & 30