fish heart - replaced simple tubular hearts
- tube w/ 4 chambers
- atrium/sinus venosus - 1st 2 chambers, for collection
- ventricle/conus arteriosus - last 2 chambers, for pumping
- order of contraction - sinus venosus >> atrium >> ventricle >> conus arteriosus
- blood passes through gills after going through heart >> much of pressure from pumping lost
amphibian/reptile heart - has 2 separate circulations due to lungs
- pulmonary circulation - between heart and lungs
- systemic circulation - between heart, rest of body
- allows for pumping fully oxygenated blood
- separated atriums prevent oxygenated/deoxygenated blood from mixing
- aorta - major artery of systemic circulation
- cutaneous respiration - breathing through the skin
mammalian/bird hearts - 4 chambered heart w/ separate atria/ventricles
- right atrium receives deoxygenated blood >> right ventricle pumps blood to lungs
- left atrium receives oxygenated blood >> left ventricle pumps blood to body
- double circulation - atrium/ventricles contract at same time
- both ventricles must pump same amount of blood
- heartbeats start in sinoatrial node (able to depolarize w/o neural activation from brain)
cardiac cycle - 2 separate pumping systems in a single organ
- diastole (rest) >> systole (contraction)
- atrioventricular valves - between atria/ventricles
- prevents blood backflow
- tricuspid valve - on right side
- bicuspid (mitral) valve - on left side
- semilunar valves - between ventricles and arteries
- pulmonary valve - on right side
- aortic valve - on left side
- coronary arteries - first arteries off the aorta, supplies heart
- superior vena cava - drains upper body
- inferior vena cava - drains lower body
- sphygmomanometer - measures blood pressure
- pressure must be large enough to push blood through capillaries, but not cause damage to arteries
- systolic pressure - peak pressure during contraction
- diastolic pressure - minimum pressure between heartbeats
- hypertension - condition w/ very strong contractions
- SA node depolarization >> AV (atrioventricular) depolarization >> bundle of His depolarization >> Purkinje fiber depolarization >> ventricle contraction
- pace-making cell - fire action potentials on their own periodically
- fibers blocked >> atria/ventricles don’t beat together
- electrocardiogram (ECG/EKG) - records the depolarization through the heart
- P wave = atrial depolarization
- QRS complex = ventricular depolarization
- T wave = ventricular repolarization (covers up atrial repolarization)
cardiac output - blood volume pumped by each ventricle per minute
- equal to amount of blood that travels through systemic/pulmonary circulations per minute
- increase heart rate, blood volume, vasoconstriction >> increase blood pressure
- baroreceptors - sense blood pressure changes
- antidiuretic hormone (ADH) - aka vasopressin, stimulates kidneys to hold more water
- aldosterone - maintains Na+, water retention in kidneys
- atrial natriuretic hormone - secreted by the heart, lowers blood volume/pressure by getting rid of Na+ and water
- nitric oxide - causes blood vessels to relax/dilate
cardiovascular diseases - leading cause of death in US
- arrhythmia - missing a heartbeat
- fibrillation - desynchronized contraction of cardiac fibers
- atrial fibrillation - decreases filling of ventricles >> not fatal
- ventricular fibrillation - decreases amount of blood pumped to body >> could be fatal
- heart attacks (cardial infarction) - due to lack of blood reaching a part of the heart
- caused by blood clots
- angina pectoris “chest pain”, not as severe as a heart attack
- stroke - blood doesn’t reach the brain properly
- effects depend on location of stroke in brain
- atherosclerosis - accumulation of fat, muscle, or cholesterol in arteries
- reduces blood flow
- arteriosclerosis - hardening of arteries
- calcium deposits in artery walls
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