Presentation is loading. Please wait.

Presentation is loading. Please wait.

The Cardiovascular System. Structure of the heart Pericardium – encloses heart. Visceral pericardium – inner layer; parietal – outer layer. Wall of heart.

Similar presentations

Presentation on theme: "The Cardiovascular System. Structure of the heart Pericardium – encloses heart. Visceral pericardium – inner layer; parietal – outer layer. Wall of heart."— Presentation transcript:

1 The Cardiovascular System

2 Structure of the heart Pericardium – encloses heart. Visceral pericardium – inner layer; parietal – outer layer. Wall of heart – 3 layers: 1 Epicardium – protects heart (reduces friction) – visceral pericardium.


4 2 Myocardium – cardiac muscle; thick middle layer. 3 Endocardium – contains blood vessels – inner lining of blood vessels.


6 Heart divided into 4 chambers. 2 atria – upper chambers, thin- walled; receive blood returning to heart. 2 ventricles – lower chambers, thicker walled; pump blood into arteries.


8 Septum divides atrium and ventricle on right from left side. R atrium receives blood from body from inferior vena cava and superior vena cava. R atrium separated from R ventricle by tricuspid valve.


10 Developing fetus - hole between L and R atria. After birth - hole supposed to close. If hole does not close - hole in heart (atrial septal defect) Blood enters lungs - breathing problems.


12 Chordae tendineae – attach cusps of tricuspid valve. Originate from papillary muscles on walls of ventricles. R ventricle pumps blood through pulmonary artery to lungs. Pulmonary valve leads into artery.


14 * L atrium receives blood from lungs through pulmonary vein. L atrium and L ventricle separated by bicuspid (mitral) valve. L ventricle pumps through aorta to entire body. Aortic valve leads into aorta.


16 Mitral valve prolapse – one or both cusps stretch and bulge into L atrium during contraction. Results in blood going back into L atrium.


18 Blood flow Blood low in O 2, high in CO 2 enters R atrium. R atrium passes blood into R Ventricle. R ventricle contracts, blood flows into pulmonary artery (to lungs) Pulmonary vein brings blood high in O 2 back to L atrium.


20 Blood passes to L ventricle. Pumped through aorta to body. 1 st 2 branches of aorta – R,L coronary arteries – supply blood to heart tissue. Cardiac veins – drain blood, join together to form coronary sinus – dump into R atrium.


22 Cardiac cycle Heart sounds made from opening and closing of valves. 1 st sound made from recoil of blood against closed AV valves (“lub”) 2 nd sound made from recoil of blood against semilunar valves. (“dup”) Heart murmurs result of incomplete valve closure resulting in swishing noise.


24 Sinoatrial node (SA node) – generates action potentials on its own (pacemaker). Impulse passes along fibers to mass of specialized tissue (atrioventricular node)


26 From AV node, moves through bundle of His (AV bundle) Divide into L and R branches underneath endocardium. Give rise to Purkinje fibers. Causes ventricular walls to contract.


28 ECG Electrocardiogram – recording of electrical changes in heart muscle. QRS complex – depolarization of ventricular fibers (ventricles contract) T wave – ventricular fibers repolarize.


30 Heart rate – duration of cardiac cycle. Stroke volume – volume of blood ejected from ventricles during contraction. Cardiac output = heart rate X stroke volume.


32 More cells stretched by incoming blood, more strongly heart walls contract to eject blood – Starling’s law of the heart. Cardiac output increases with increasing exercise and blood flow.


34 Heart rate monitored in medulla oblongata of brain. Increase in blood pressure – stretch sensors send message to brain to slow heart rate down.


36 Blood vessels Arteries – carry oxygenated blood away from heart. Branch into arterioles, then capillaries. Artery – 3-layered wall surrounding interior (lumen).


38 1 Tunica intima – innermost layer. 2 Tunica media – thick smooth muscle layer (middle) 3 Tunica adventitia – outer layer; anchors artery to neighboring structures.


40 Vasoconstriction – vessel decreases in diameter. Vasodilation – vessel increases in diameter. Pulmonary artery – carries deoxygenated blood away from heart (toward lungs)


42 Capillaries – smallest vessels. Permit exchange of nutrients, removal of wastes at tissue level. Thin, permeable walls to allow diffusion to occur.


44 Veins – carry deoxygenated blood back to heart. Capillaries join venules, join to form veins. Same 3 layers; tunica media not very thick.


46 Blood pressure in veins not high, so veins need valves to prevent backflow. Blood must flow against gravity back to heart.


48 Blood Pressure Blood pressure – force exerted by blood against walls of vessels. Systolic pressure – stretch of arteries to allow for blood flow pumped from heart. Diastolic pressure – relaxation.


50 Pulse – expanding, recoiling of arterial walls. Represents # of heartbeats per minute.


52 Factors affecting blood pressure 1 Cardiac output – increase in cardiac output increases blood pressure. 2 Peripheral resistance – friction + drag in vessels; increases blood pressure. Vasoconstriction increases b.p.


54 3 Blood volume – decrease causes drop in b.p. Sympathetic nervous system – causes rise in b.p, heart rate. Parasympathetic – decrease.


56 Hormones regulate b.p. Epinephrine, norephinephrine – rise, fall of b.p. Antidiuretic hormone – rise in b.p. Kidneys aid in regulation – drop in b.p. releases renin; renin causes formation of angiotensin.

57 Angiotensin – vasoconstriction. Stimulates release of aldosterone – increases b.p.


59 Circulatory Pathways 1 Pulmonary circulation – pulmonary trunk carries blood from R ventricle. Divides into R and L pulmonary artery, into capillaries. O 2 picked up in lungs, brought back to heart via pulmonary veins.


61 Arteries 2 Systemic – blood leaves L ventricle into ascending aorta. Branches into R, L coronary arteries (supply heart wall). Aorta curves to back (aortic arch) 3 branches – brachiocephalic, L common carotid, L subclavian.


63 Aorta turns downward (descending aorta). Section above diaphragm – thoracic aorta; branch into intercostal arteries (supply thoracic wall). Below diaphragm – abdominal aorta.


65 Branches into celiac artery (liver, spleen, stomach, pancreas), superior mesenteric artery (small intestine), suprarenal arteries (adrenal glands), renal arteries (kidneys), inferior mesenteric artery (large intestine). Divides into R, L iliac (to lower legs)


67 Pelvis, lower limbs – common iliac divides into internal, external iliac. External iliac – becomes femoral. Forms deep femoral artery (flexor muscles of thigh), popliteal artery (knee), anterior, posterior tibial arteries.

68 Head, neck – from common carotid, subclavian. R common carotid arises from brachiocephalic. R, L common carotid branch into external, internal carotid.


70 Shoulder, upper limbs – from subclavian. Axillary artery – near armpit. Continues down arm as brachial artery; divides into ulnar, radial arteries.


72 Veins Head, face veins – blood drained into R, L external jugular. Merge with subclavian veins  internal jugular  brachiocephalic vein  superior vena cava.


74 Upper limbs – ulnar, radial vein  brachial vein  axillary vein. Major superficial arm veins – basilic (forearm to middle of upper arm), cephalic (wrist to shoulder), median cubital vein (where blood is drawn).


76 Inferior vena cava – longest vein in body – great saphenous vein, joins with femoral vein. Abdomen – hepatic portal system – blood from capillaries of digestive tract to liver only. Dumps blood into superior, inferior mesenteric veins.


78 Diseases 1 Congestive heart failure – can’t pump blood to body. Bad circulation to body  increased pressure, fluid leaking in lungs. Caused by damage to cardiac muscle. Symptoms – shortness of breath, swelling in lower legs.


80 2 Hypertension – increase in blood pressure. Due to narrowing of blood vessels (atherosclerosis) or hardening of vessels (arteriosclerosis)


82 3 Endocarditis – infection of lining of heart due to bacterial infection. Can cause embolus (blood clot) 4 Aneurysm – sac formation in vessel or heart chamber; can produce tear in vessel (hemorrhage)


Download ppt "The Cardiovascular System. Structure of the heart Pericardium – encloses heart. Visceral pericardium – inner layer; parietal – outer layer. Wall of heart."

Similar presentations

Ads by Google