Circula5on. Chapter 24: Circula5on. Circula5on. Circula5on. Cardiac Circula5on. Cardiac Circula5on 3/18/15

Transcription

1 Chapter 4: Circula5on Transport of O and CO via blood Cardiac circula5on Systemic circula5on Compara5ve vertebrate circula5on Fish Amphibians and rep5les Circula5on Bulk flow of blood through series of vessels Serves several func5ons:. Transports O Supply rate to muscles determined by rate and amount circula5ng. Regulates blood pressure. Aids in thermoregula5on Allows for increased/decreased heat loss Circula5on Bulk flow of blood through series of vessels Serves several func5ons:. Transports O ß Most important func4on!! Supply rate to muscles determined by rate and amount circula5ng. Regulates blood pressure. Aids in thermoregula5on Allows for increased/decreased heat loss Circula5on Cardiac circula5on: movement of fluids (blood) through the heart Systemic circula5on: movement of fluids (blood) to body 5ssues Myocardium: cardiac muscle 5ssue in heart. Intercollated discs between muscle fibers connected by gap junc5ons Fast, electrical impulses Ensures synchronous heart beats Myocardium: cardiac muscle 5ssue in heart. Intercollated discs between muscle fibers connected by gap junc5ons Fast, electrical impulses Ensures synchronous heart beats. APs generated at regular intervals. APs have long dura5on Muscle movement via contrac5ons, not twitches

2 Muscle contrac5ons drive blood flow through heart via pumping ac5on One- way valves direct blood flow and prevent backflow Four chambered hearts: LeU atrium receives O rich blood from lungs Right atrium receives deoxygenated blood from 5ssues LeU and right ventricles pump blood Movement of O - rich blood:. Enters leu atrium through pulmonary vein. Into leu ventricle. Pumped out of ventricle via systemic aorta à 5ssues throughout body Red = oxygenated blood Blue = deoxygenated blood Characteris5cs of Return of deoxygenated blood: 4. Enters right atrium via super vena cava 5. Into right ventricle 6. Pumped out of heart via pulmonary trunk à to lung Cardiac output: volume of blood pumped per unit 5me (ml/min) Cardiac output = Heart rate (beats/min) * Stroke volume (ml/beat) Red = oxygenated blood Blue = deoxygenated blood Characteris5cs of Cardiac output: volume of blood pumped per unit 5me (ml/min) Cardiac output = Heart rate (beats/min) * Stroke volume (ml/beat) Heart requires nearly constant, steady supply of O Coronary circula4on: movement of O rich blood Coronary artery à Capillaries à coronary veins à Right atrium Darker red = more O Characteris5cs of All vertebrates have myogenic hearts ( beginning in muscle ) Contrac5ons ini5ated by pacemaker cells in SA node Cluster of cells that automa5cally generate impulses

3 /8/5 Characteris5cs of Cardiac Circula5on Conduc5on: process by which depolariza5on spreads Electrical impulses via gap junc5ons travel fast Ensure rhythmic waves of depolariza5on Characteris5cs of Cardiac Circula5on Electrocardiogram (EKG) measures voltage difference over 5me Video Video (long) Chapter 4: Circula5on Transport of O and CO via blood Cardiac circula5on Systemic circula4on Compara5ve vertebrate circula5on Systemic circula5on Perfusion: blood flow through vessels throughout body Difference in pressure within blood compared to environment à blood pressure Mammals and birds Fish Amphibians and rep5les Systemic circula5on Systole: highest pressure during contrac5on Diastole: lowest pressure during relaxa5on Systemic circula5on Perfusion: blood flow through vessels throughout body Depends on:. Blood pressure. Fluid- column effects

4 Fluid- column effects Pressure within a column greater at base Pressure increases with height of column This is why BP is measured while laying or sieng down Fluid- column effects Pressure decreases with distance above heart Pressure increases with distance below heart This is why BP is measured at level with heart Eleva5ng extremi5es when hurt Open vs. Closed Circulatory Systems Open systems Use less energy to move blood Can func5on as a hydrosta5c skeleton Mainly invertebrates (except earthworms and larger mollusks) What is the difference? Closed systems Maintain higher blood pressure More effec5ve O transport Can support larger and more ac5ve animals with higher O demands All vertebrates Chapter 4: Circula5on Transport of O and CO via blood Cardiac circula5on Systemic circula5on Compara4ve vertebrate circula4on Fish Amphibians and rep5les Systemic and pulmonary circulatory systems are connected in series De- oxygenated blood: From systemic to pulmonary Oxygenated blood: From pulmonary to systemic Closed circulatory system 4- chambered heart: atria, ventricles O - rich separate from O - poor blood No mixing à much more efficient gas transport Blood travels through heart TWICE 4

5 : : blood flow outside of the heart. Arteries Thick, muscular walls sustain greater pressure Elas5c cell walls to handle pumping ac5on during contrac5on/ relaxa5on Carry O rich blood : Arteries become smaller with distance from heart (lower pressure). Microcapillary beds Arterioles Diameter controls flow rate into beds Sensory s5muli from CNS regulates vasoconstric5on and vasodila5on. Microcapillary beds Arterioles Capillary beds Main site of gas exchange Dense mass of mul5ples branches Thin walls for easy gas exchange :. Microcapillary beds Arterioles Capillary beds Venules Connec5ve 5ssues and muscle cells : :. Veins Return deoxygenated blood to heart Increase in diameter closer to heart Valves prevent backflow Very high blood pressure due to high O demands 5

6 High O demand during exercise requires increased rate of delivery. Increase cardiac output CO = amount of blood pumped per heart beat Athletes tend to have higher CO High O demand during exercise requires increased rate of delivery. Increase cardiac output. Extract more O per unit blood Venous blood more dexogyenated during exercise. Vasodilate capillary beds in muscles Endurance builds more extensive beds Chapter 4: Circula5on Transport of O and CO via blood Cardiac circula5on Systemic circula5on Compara4ve vertebrate circula4on Fish Amphibians and rep5les Fish Circulatory plan Closed circula5on: atrium, ventricle Blood flow:. Pumping ac5on moves blood from heart to ventral aorta. Oxygen uptake occurs in capillary beds in gills. Oxygenated blood sent to systemic 5ssues 4. Deoxygenated blood returns via great veins 4 Fish Circulatory plan Differ from mammals and birds:. A single pump of the heart circulates blood Slow blood flow to capillaries and back to heart Single pump must be strong!. Lower cardiac output Lower O demand Amphibian circula5on - chambered heart: atria, ventricle circuits:. Deoxygenated blood leaves right atrium à lungs and skin to release CO and acquire O 6

7 Amphibian circula5on circuits:. Deoxygenated blood leaves right atrium à lungs and skin to release CO and acquire O. Oxygenated blood leaves leu atrium à systemic 5ssues Amphibian circula5on O rich and O poor blood mix in the ventricle No valves to prevent backflow Structure and arrangement of myocardial muscles prevents complete mixing 7