HEART Located in the pericardial/thoracic cavity (contains serous fluid to reduce friction) Lined by a serous membrane called the pericardium 3 layers – Epicardium-outer layer that protects heart – Myocardium-thick middle layer of cardiac muscle that forces blood out the heart chambers – Endocardium-inner layer that contains blood vessels that attach to the heart
4 chambers – Atria: upper 2 chambers that have thin walls and receive blood returning to heart – Ventricles: lower 2 chambers that have thick walls and receive blood from atria then contract to force blood out of heart
Interventricular Septum-solid wall that separates the heart into left and right halves Coronary arteries-supply blood to the hearts tissues (the 1 st 2 branches of the aorta) Cardiac veins& Coronary sinus: blood returns to the right atrium through these Atrioventricular valves: tricuspid/bicuspid Semilunar valves: pulmonary/aortic
BLOOD VESSELS Artery arteriole capillary venule vein (away from heart) *site of nutrient, (back to heart) gas, and waste exchange Closed system of blood circulation – Pulmonary circuit: sends deoxygenated blood to lungs – Systemic circuit: sends oxygenated blood and nutrients to all body cells and removes wastes The heart pumps 7,000 liters of blood through the body each day, contracting some 2.5 billion times in an average lifetime.
CARDIAC CYCLE The events of one complete heart beat (1 contraction & relaxation) that lasts about.8 sec. Both atria contract while ventricles are relaxing. Both atria relax while ventricles are contracting. Pressure within the chambers rises and falls causes the valves to open and close. When ventricular pressure exceeds atrial pressure, the AV valves open. Papillary muscles contract and pull chordate tendineae to open and close the valves. They aid in preventing back flow of blood.
Heart beat sound: lupp-dupp Lupp occurs when the AV valves are closing Dupp occurs when the semilunar valves are closing Cardiac conduction system coordinates the events of the cardiac cycle. S-A node (sinoatrial node) or pacemaker upper right atrium generate the hearts rhythmic contractions A-V bundle Purkinje fibers
Electrocardiogram (ECG): recording of the electrical changes that occur in the myocardium during the cardiac cycle.
ECG cont… S-A node triggers a cardiac impulse, atrial fibers depolarize (contraction), producing an electrical charge. Ventricle walls are thicker causing a greater electrical charge. Adult heart rate 60-100 beats per minute. Well trained athlete 40-60 bpm. Heart rate influences Emotional upset, anxiety Temperature change Ion changes (K +, Ca +2 )
BLOOD PRESSURE Force blood exerts against the blood vessel walls. Specifically, pressure in arteries supplied by branches of the aorta. Forces blood throughout the body. Blood vessels walls are constructed to adequately carry blood (pg. 358) Artery arteriole capillary venule vein Highest pressure Lowest pressure Cut an artery, blood squirts out; cut a vein, blood flows out Contraction of the human heart creates enough pressure to squirt blood 30 ft.
Blood Pressure cont.. Systolic pressure: maximum pressure in the arteries during ventricular contraction. Diastolic pressure: lowest pressure remaining in the arteries before the next ventricular contraction. Average blood pressure 120/80 systolic/diastolic Arterial Pulse Temporalfemoral Facialpopliteal Carotidposterior tibial Brachialdorsalis pedis radial
Factors that influence blood pressure Stroke volume: amount of blood discharged from ventricle with each contraction Blood volume: sum of all blood components Peripheral resistance: friction b/w the blood and blood vessel walls Viscosity: consistency of blood
CARDIOVASCULAR DISORDERS Tachycardia- abnormally fast heart beat – above 100 BPM Bradycardia – slow heart beat – below 60 BPM Murmur – abnormal heart sound due to incomplete closure of heart valves Idiopathic cardiomyopathy – enlarged heart Congenital defects – defect present at birth Stenosis – narrowing of an opening Myocardial infarction – heart attack Angina pectoris – pain in the chest Hypertension – high blood pressure (140/90)
Arrhythmias – abnormal heart rhythms Atherosclerosis – a build-up of plaque in the arteries Arteriosclerosis – hardening of the arteries Coronary bypass – surgery using a vein from the leg or artery from the chest to correct blocked coronary arteries Thrombus – blood clot Embolus – moving blood clot Ischemia – lack of blood flow and oxygen to heart Aneurysm – a permanent weakness in an artery Angioplasty – a catheter is inserted into an artery in the leg or arm and fed into a coronary artery Cardiac output – the amount of blood the heart pumps each minute