The Cardiovascular System Chapter 15

Human Circulation Double loop circulation Pulmonary circuit Systemic circuit

15. 1 The Heart

Size and Location of the Human Heart Location: Bordered laterally by the lungs Posteriorly by the vertebrae Anteriorly by the sternum

Covering of the Heart Pericardium Fibrous pericardium – surrounds a more delicate membrane Visceral pericardium (epicardium) Parietal pericardium – epicardium folds to line inside of fibrous pericardium Between the parietal and visceral layers is pericardial cavity Contains serous fluid Reduces friction

Wall of the Heart Epicardium Myocardium Endocardium

Epicardium Outermost layer of the heart Corresponds with visceral pericardium Contains Capillaries and nerve fibers Fat tissue along blood vessels

Myocardium Middle layer Cardiac muscle to pump blood Muscle tissue is arranged in layers, separated by vascular connective tissue

Endocardium Innermost layer Epithelium, connective tissue Blood vessels Purkinje fibers Specialized cardiac muscle fibers – propagate signal through heart Lines all heart chambers, valves and lining extends into blood vessels

Heart Chambers and Valves 4 chambers 2 atria 2 ventricles

Atrium (Atria) Upper chambers of the heart Receive blood Thin walled

Ventricles Lower chambers Very muscular Right and Left Ventricles separated by the interventricular septum

Valves of the Heart Right Atrioventricular Valve (tricuspid) Pulmonary Valve Tricuspid valve NO chordae tendineae or papillary muscles Left Atrioventricular Valve (Mitral Valve) Bicuspid valve Aortic Valve

Heart Chambers and Valves Right atrium Receives blood from the superior vena cava, inferior vena cava Coronary sinus – from myocardium

Valves Chordae tendineae – attach to tricuspid on ventricular side Originate from papillary muscles Prevent tricuspid valve from flipping into the atrium

Right Ventricle Thinner walls than the left ventricle Pumps blood to the lungs Exits heart and into the pulmonary trunk Divides into left and right pulmonary arteries

Return to the heart… From lungs, blood exits through pulmonary veins (4) Two from right lung, two from left lung Blood enters left atrium

Left Atrium Blood passes from left atrium to left ventricle through the mitral valve

Left Ventricle and Aorta Left ventricle contracts Closing mitral valve Sends blood to aorta through aortic valve

Blood Supply to the Heart Coronary arteries – from aorta Right and left Cardiac veins – drain deoxygenated blood from heart Join at the coronary sinus Empties into right atrium

Label the Heart with Blood Flow

15.3 Heart Actions

Heart Actions Systole Contraction Depends on which part of the heart Atrial systole Ventricular systole Diastole Relaxation Atrial diastole Ventricular diastole

Cardiac Cycle Cycle of contractions between the atria and ventricles

Heart Sounds Lubb Dubb Lubb – ventricular systole AV valves are closing Dubb – ventricular diastole Pulmonary and aortic valves are closing

Heart Sounds Can tell you the condition of the heart valves Murmur: some blood leaks back through the valve Many murmurs are harmless Some can be a sign of serious valve damage

Electrocardiogram

ECG (EKG) Measures electrical changes within the myocardium during cardiac cycle

Steps of an ECG P wave QRS complex Q wave R wave S wave T wave

P Wave Depolarization of atrial fibers

QRS Complex Indicates depolarization of ventricular fibers prior to contraction

T Wave Repolarization of ventricular fibers after contraction

ECG Uses Assess heart’s ability to conduct impulses PQ interval : time to travel from SA node through AV node

SA Node Coordinates events of the cardiac cycle Sinoatrial node Right atrium near opening to superior vena cava Pacemaker : generates heart’s rhythmic contractions

AV Node Atrioventricular node Coordinate contraction of ventricles together AND after the atria Impulse travels to AV bundle (bundle of His) and move through ventricular myocardium Through right and left bundle branches then to myocardium via Purkinje fibers Allow ventricle to contract as one unit

Nodes of the Heart

Regulation of Cardiac Cycle Vagus nerves : originate in the medulla oblongatta Innervate and regulate heart

15.4 Blood Vessels

Types of Blood Vessels Arteries Arterioles Capillaries Venules Veins

Blood Vessel Tunics 3 layers (tunics) Tunica interna (innermost) Epithelial cells Tunica media (middle) Smooth muscle Tunica externa (outermost) Tougher connective tissue, elastin, collagen

A rteries Muscular Very elastic Carry blood A WAY from the heart Smaller arteries = arterioles

Veins Little muscle Large lumen (space for blood to pass through), less muscle Brings blood to the heart Contain valves Flow through veins is assisted by skeletal muscle Small veins = venules

Arteries vs. Veins

Capillaries Smallest blood vessel Extension of innermost layer of arteries/veins – tunica interna Single layer of epithelial cells Allow for easy exchange of materials from blood to tissues

15.7 Arterial System

Leaving the heart…

Aorta Largest artery (diameter) in body Three major arteries come from the aortic arch Brachiocephalic artery Left common carotid artery Left subclavian artery

Brachiocephalic Artery Supply blood to the upper limb, head Divides to give rise to Right common carotid artery Right subclavian artery

Descending Aorta Extends from aortic arch down the body Thoracic aorta Bronchial arteries Esophageal arteries

More Descending Aorta Abdominal Aorta Celiac artery Left gastric (upper digestive tract) Splenic (spleen …duh…) Hepatic (liver) Phrenic artery (Diaphragm) Superior mesenteric (Intestines (most))

Still the descending aorta… And MORE from the Abdominal Aorta Suprarenal (adrenal glands) Renal (kidneys) Gonadal (gonads …duh…) Inferior Mesenteric (parts of the colon, rectum) Lumbar (muscle of skin of posterior abdominal wall) Medial Sacral (sacrum, coccyx)

Arteries of the Brain, Neck, Head Vertebral Through transverse processes of cervical vertebrae Enter skull through foramen magnum External carotid Internal carotid

Arteries of the Shoulder and Upper Limb From subclavian artery Axillary artery (shoulder, upper chest) Brachial artery (along the humerus) Radial artery Ulnar artery

Arteries of the Lower Limb Abdominal aorta splits to form common iliac arteries Internal iliac artery (pelvic region) External iliac artery (main blood supply to lower limbs) Inferior epigastric artery Deep circumflex iliac artery

Arteries of the Lower Limb External iliac artery becomes the femoral artery (deep femoral, superficial femoral) Femoral artery becomes the popliteal artery as it passes over the patella Divides Anterior tibial artery Posterior tibial artery

Venous System

How Veins Work Capillaries join to form venules Venules join to form small veins Small veins join to form large veins

Veins Veins typically are paired with an artery Renal artery and the renal vein Bring blood to the kidney from the heart, take blood from the kidney to the heart BUT not always Venous blood flow is assisted by skeletal muscle contraction

Veins Superior Vena Cava Inferior Vena Cava Both lead to the right atrium from the body

Veins from the Brain, Head, Neck External jugular vein Internal jugular vein Brachiocephalic vein Right subclavian vein Right axillary vein

Veins from the Upper Limb and Shoulder Paired Radial veins Ulnar veins Brachial veins

Veins from the Abdominal Viscera Originate in the capillaries of the stomach, intestines, pancreas, spleen Merge at the hepatic portal vein to the liver Superior mesenteric vein (small intestine, portions of colon) Inferior mesenteric vein (colon and rectum) Gastric veins (stomach) Splenic vein (spleen, pancreas)

Hepatic Portal System

What happens in the liver? Regulation of glucose within the body Phagocytosis of microorganisms Breakdown of toxins After the liver, blood enters the hepatic veins and the inferior vena cava

Veins from Lower Limb and Pelvis Anterior tibial vein Posterior tibial vein Popliteal vein Femoral vein Great saphenous vein (largest vein in the body – extends from medial foot to the femoral vein) External iliac vein

Cardiovascular Diseases and Abnormalities 1.Cardiac Arrest 2.Stroke 3.Aneurysm 4.Arteriosclerosis / Atherosclerosis 5.Murmur 6.Hypertension 7.Myocardial Infarction What causes the disease/abnormality? What are some possible effects of the disease/abnormality? How is it diagnosed? Possible treatments?

Cardiac Arrest

Stroke

Aneurysm

Arteriosclerosis / Atherosclerosis

Murmur

Hypertension

Myocardial Infarction