Heart and Blood Vessels

Major Arteries and Veins Subclavian artery Subclavian vein Jugular vein Carotid artery Superior vena cava Inferior vena cava Common iliac vein Common iliac artery Femoral artery Great saphenous vein Renal artery Renal vein Aorta Femoral vein

Blood Vessels—Arterial System Structure: endothelium, middle, outer layers Functions Arteries carry blood away from heart Arterioles and precapillary sphincters control pressure Capillaries exchange nutrients, waste, and defensive cells between vessel and tissue

Arterioles and Capillaries

Capillary Structure

Blood Vessels—Venous System Structure: three layers, thin-walled Functions: carry blood toward the heart Mechanisms in blood return Contraction of skeletal muscles One-way valves Pressure changes associated with breathing

Blood Vessels—Venous System

Blood Vessels—Summary Inner layer: Endothelium Middle layer: Smooth muscle with elastic fibers Outer layer: Connective tissue Connective tissue Endothelium Vein Venule Artery Arteriole Capillary Direction of blood flow Tissue cells Epithelial cells of capillary endothelium Smooth muscle

Lymphatic System Function Maintains blood volume Also functions in immune system Structure Blind-ended capillaries Lymphatic vessels Lymph is the circulating fluid

The Heart Figure 8.7 Superior vena cava Pulmonary semilunar valve Right atrium Right AV valve Right ventricle Inferior vena cava Pulmonary trunk Left pulmonary veins Left atrium Left AV valve Aortic semilunar valve Chordae tendineae Papillary muscles Left ventricle Septum Right pulmonary artery Left pulmonary artery Aorta

The Heart Structure Layers: epicardium, myocardium, and endocardium Chambers: two atrias, two ventricles Valves Two atrioventricular valves: tricuspid and bicuspid (mitral) Two semilunar valves: pulmonary and aortic

Pulmonary Circuit— Oxygenation of Blood Pathway Deoxygenated blood from the body into heart 1. Through the vena cava to the right atrium 2. Through the right atrioventricular valve to the right ventricle 3. Through the pulmonary semilunar valve to the pulmonary trunk and the lungs

Pulmonary Circuit— Oxygenation of Blood Pathway Oxygenated blood from lungs to heart 1. Through the pulmonary veins to the left atrium 2. Through the left atrioventricular valve to the left ventricle

Systemic Circuit—Delivery of Oxygenated Blood to Tissues Pathway Oxygenated blood from the heart to tissues 1. Through the aortic semilunar valve to the aorta 2. Through branching arteries and arterioles to tissues 3. Through the arterioles to capillaries

Systemic Circuit: Return of Blood to the Heart Pathway Deoxygenated blood returns to heart 1. From capillaries into venules and veins 2. To the vena cava and into the right atrium

Pulmonary and Systemic Circuits Subclavian artery Subclavian vein Jugular vein Carotid artery Superior vena cava Inferior vena cava Common iliac vein Common iliac artery Femoral artery Great saphenous vein Renal artery Renal vein Aorta Femoral vein

Cardiac Cycle

Heart Sounds and Heart Valves Lub-dub (typical heart beat) Sounds are valves closing Heart murmurs

Cardiac Conduction System Coordinates Contraction SA node: cardiac pacemaker AV node: relays impulse AV bundle and Purkinje fibers: carry impulse to ventricles

Electrocardiograms (EKG/ECG) Measure the electrical impulses of the heart Three formations P wave: impulse across atria QRS complex: spread of impulse down septum, around ventricles in Purkinje fibers T wave: end of electrical activity in ventricles Arrythmias, ventricular fibrillation can be detected

Electrocardiograms (EKG/ECG) (cont.)

Blood Pressure Definitions Systolic pressure Diastolic pressure Measurement Sphygmomanometer What’s a “normal” reading? What would be considered “high” or “low” blood pressure?

How Blood Pressure is Measured Figure 8.16

Blood Pressure (cont.) Hypertension: high blood pressure The silent killer Hypotension: blood pressure too low Clinical signs: dizziness, fainting Causes: orthostatic, severe burns, blood loss

Regulation of the Cardiovascular System: Baroreceptors Baroreceptors: pressure receptors in aorta and carotid arteries Steps in mechanism 1. Blood pressure rises, vessels stretched 2. Signals sent to brain in the cardiovascular center 3. Heart signaled to lower heart rate and force of contraction 4. Arterioles vasodilate, increasing blood flow to tissues 5. Combined effect lowers blood pressure

Regulation: Nervous and Endocrine Factors Central Nervous System signals Sympathetic nerves: constrict blood vessels, raising blood pressure Parasympathetic nerves: dilate blood vessels, lowering blood pressure Hormones: epinephrine (adrenaline) Local requirements dictate local blood flow Exercise: increased blood flow and cardiac output

Cardiovascular Disorders Angina pectoris: a warning, chest pain Myocardial infarction/heart attack: permanent cardiac damage Congestive heart failure: decrease in pumping efficiency Embolism: blockage of blood vessels Stroke: impaired blood flow to the brain

Reducing the Risk of Cardiovascular Disease Smoking: don’t Blood lipids: monitor cholesterol levels Exercise: regular and moderate Blood pressure: treat hypertension

Reducing the Risk of Cardiovascular Disease (cont.) Weight: being overweight increases risk of heart attack and stroke Control of diabetes mellitus: early diagnosis and treatment delays onset of related problems Stress: avoid chronic stress

Cardiac Anatomy Practice