Biology 250:Human Anatomy Spring 2005 Cardiovascular System

Cardiovascular Overview Heart: pumps blood throughout the body –Involuntary striated muscle Arteries: carries blood away from the heart –Carries oxygenated blood to body Veins: carries blood to the heart –Carries de-oxygenated blood to the heart Capillaries: connect arteries, veins

Heart Usually the size of a fist Weighs between grams (< 1 lb) Sits with the mediastinum –Medial cavity of the thorax Base: broad, flat –Directed toward the right shoulder Apex: pointed end of heart –Points inferiorly toward the left hip

Coverings of the Heart Pericardium Double-walled sac enclosing the heart Dense Connective Tissue Purposes of Pericardium: 1.Protection 2.Anchors heart to surrounding structure 3.Prevents overfilling of heart

Layers of Heart Wall 3 Layers of Heart Wall 1.Epicardium Superficial Layer; usually filled with fat 2.Myocardium Middle Layer; composed of cardiac muscle 3.Endocardium Deepest Layer; Squamous Epithelium

Heart Chambers 4 Chambers of the Heart: 2 Superior Chambers –Right Atrium, Left Atrium –Relatively thin heart wall 2 Inferior Chambers –Right Ventricle, Left Ventricle –Thick heart wall (produces strong contraction) Interatrial/ventricular septum

Right Atrium Superior/Right Chamber of Heart De-Oxygenated Blood From Body 3 Major Veins: 1.Superior Vena Cava –Blood from superior portion of body 2.Inferior Vena Cava –Blood from inferior portion of body 3.Coronary Sinus –Blood from the heart itself

Right Ventricle Inferior/Right Chamber of Heart De-Oxygenated Blood from Right Atrium Relatively thick heart wall 2 Major Arteries: 1.Left Pulmonary Artery De-oxygenated blood to left lung 2.Right Pulmonary Artery De-oxygenated blood to right lung ONLY arteries with de-oxygenated blood

Left Atrium Superior/Left Chamber of Heart Oxygenated Blood From Lungs 2 Major Veins: 1.Right Pulmonary Vein Oxygenated blood from right lung 2.Left Pulmonary Vein Oxygenated blood from left lung ONLY veins with oxygenated blood

Left Ventricle Inferior/Left Chamber of Heart Oxygenated blood from Left Atrium Thick Heart Wall Pumps blood through major artery: –Aorta: branches into all other arteries of body

Coronary Arteries Arteries which supply the heart Major Coronary Arteries 1.Left Coronary Artery 2.Anterior Interventricular Artery 3.Circumflex Artery 4.Right Coronary Artery 5.Marginal Artery 6.Posterior Interventricular Artery CABG

Heart Valves Separate the chambers of the heart Prevent back-flow of blood Atrioventricular Valves (AV) –Separate the atrium from the ventricles 1.Right AV Valve (Tricuspid Valve) 2.Left AV Valve (Bicuspid or Mitral) –Contain Chordae Tendineae

Heart Valves (Cont.) Semilunar Valves (SL) –Resemble half moons 1.Pulmonary Semilunar Valve –Prevents back-flow from Pulmonary Arteries into Right Ventricle 2.Aortic Semilunar Valve –Prevents back-flow from Aorta into Left Ventricle

Common Valve Deficiencies Incompetent Valve –“Leaky” Valve; does not close properly Valvular Stenosis –“Stiff” Valve; does not open properly “Heart Murmur”

Blood Flow Through Heart Blood enters R Atrium from: 1.Superior Vena Cava 2.Inferior Vena Cava 3.Coronary Sinus Travels from R Atrium to R Ventricle: –Tricuspid Valve is open Travels from R Ventricle to Lungs –Pulmonary Semilunar Valve open –R Pulmonary, L Pulmonary Arteries

Blood Flow Through Heart (Cont.) Travels from Lungs to L Atrium via: –R Pulmonary, L Pulmonary Veins Travels from L Atrium to L Ventricle –Bicuspid (Mitral) Valve is open Travels from L Ventricle to Aorta –Aortic Semilunar Valve is open Travels from Aorta to rest of body

Cardiac Cycle Systole –Period of ventricular contraction Diastole –Period of ventricular relaxation –Ventricles receive blood from atria Heart Sounds –“Lub-Dub” –1 st sound: closing of AV Valves (Systole) –2 nd sound: closing of Semilunar Valves (Diastole)

Cardiac Output Heart Rate –Number of heart beats per minute Stroke Volume –Volume of blood pumped with each beat Cardiac Output –Amount of blood pumped by each ventricle per l minute –Calculated by heart rate x stroke volume

Common Heart Dysfunctions Tacycardia: more than 100 beats/minute Bradycardia: less than 60 beats/minute Congestive Heart Failure (CHF) –Back-up of blood; inadequate pumping –Peripheral Congestion –Pulmonary Congestion Myocardial Infarction (MI) –Heart Attack; myocardium dies

Blood Vessels 3 Major Blood Vessels: 1.Arteries Carry blood away from the heart 2.Veins Return blood to the heart 3.Capillaries Actual site of nutrient, waste exchange

Blood Vessel Structure 3 Layers of Walls (Tunics): 1.Tunica Interna (Tunica Intima) Innermost layer of the blood vessel 2.Tunica Media Middle layer of blood vessel 3.Tunica Externa (Tunica Adventitia) Outtermost layer of blood vessel

Blood Vessel Structure (Cont.) Lumen –Central canal of the blood vessel Portion where the blood actually flows Vasoconstriction –Reduction of the size (diameter) of the lumen Vasodilation –Increase of the size (diameter) of the lumen

Arterial System 3 Types of Arteries: 1.Elastic (Conducting) Arteries –Large arteries close to the heart –Large lumen, low resistance 2.Muscular (Distributing) Arteries –Deliver blood to specific body organs –Composed of mainly tunica media 3.Arterioles –Smallest of arteries; interact with capillaries

Capillaries 3 Types of Capillaries: 1.Continuous Capillaries Abundant in skin and muscles 2.Fenestrated Capillaries Found where filtration, absorption are required 3.Sinsusoidal Capillaries Very leaky, found in liver, bone marrow

Venous System Venules –Smallest veins; interact with capillaries –Join together to form veins Veins –Contain very large lumens –Contains virtually no smooth muscle –Venous Valves Varicose Veins Deep Vein Thrombosis (DVT)

Pulse / Blood Pressure Pulse: expansion of arteries w/ each beat –Pressure Points Blood Pressure –Systolic: 1 st number ( mm Hg) –Diastolic: 2 nd number (75-80mm Hg) –Hypotension: systolic BP < 100mm Hg –Hypertension: systolic BP > 140mm Hg

Major Arteries Upper Body 1.Carotid Artery 2.Vertebral Artery 3.Aorta 4.Brachial Artery 5.Radial Artery 6.Ulnar Artery

Major Arteries (Cont.) Lower Body 1.Abdominal Aorta 2.Iliac Artery 3.Femoral Artery 4.Popliteal Artery 5.Anterior Tibial Artery 6.Posterior Tibial Artery 7.Dorsalis Pedis Artery