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51 Cards in this Set
- Front
- Back
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Chambers of heart surrounded by...
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myocardium, heart muscle, which pump blood by alternating contraction (systole) and relaxation (diastole)
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Valves between chambers respond to...
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pressures
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Blood flow measured as cardiac output (mL/min) =
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= heart rate (beats/min) X stroke volume (mL/beat)
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Myocardium supplied with O2 via...
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coronary circulation if myocardium is compact, or by luminal blood if it is spongy
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Control of heart rate and stroke volume can be...(3 things)
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nervous, hormonal, or intrinsic
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Myocardial depolarization originates in...
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pacemaker cells; moves through heart in a controlled manner by conduction
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Pacemaker cells are
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muscle cells (myogenic) or neurons (neurogenic)
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Arteries carry blood BLANK, veins carry blood BLANK
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Arteries carry blood away, veins carry blood toward heart
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Blood generally flows from blank to blank pressure, but also has BLANK if it is moving
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moves from high to low pressure, but also has momentum
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AV valve opens when?
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atrial pressure exceeds ventricular pressure
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Aortic valve opens when?
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ventricular pressure exceeds aortic pressure
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Isovolumetric contraction/relaxtion are...
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changes in myocardial tension without changes in chamber volume; serve to build pressure in ventricle
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Octopus heart gets blood from
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coronary veins
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Some fish hearts have both...
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coronary circulation and spongy myocardium
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Vertebrates have BLANK depolarization, while invertebrates have BLANK depolarization
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Vertebrates have myogenic depolarization, invertebrates generally neurogenic depolarization
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S-A node is...
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the pacemaker, with a fast endogenous rhythm that entrains other muscle cells
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How does depolarization spread through myocardium?
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by electrical synapses
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What depolarizes in heart first?
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Atria depolarizes first, spreading excitation to A-V node
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A-V node has BLANK excitation, allowing atria to contract BLANK
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A-V node has delayed excitation, allowing atria to contract first
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When the A-V depolarizes...
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atria are already repolarizing
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What conducts depolarization from A-V node to all parts of ventricles rapidly?
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fiber bundles
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Ex: crustaceans have neurogenic depolarization
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neurons 6 - 9 act as cellular oscillator and CPG, excites remaining neurons and muscle cells of heart; each muscle cell innervated
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What determines velocity and direction of blood flow? (3)
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pressure gradients, kinetic energy, and gravitational potential energy
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Flow through a vessel is proportional to...BLANK, and inversely proportional to the BLANK
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Proportional to difference in pressure between ends; inversely proportional to vascular resistance
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Vascular resistance...
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increases with increasing vessel length and with decreasing vessel radius to fourth power; flow is HIGHLY sensitive to changes in vessel radius
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Viscosity of blood causes what as it moves through vessels?
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a loss of pressure as KE is converted to heat; pumping blood is costly
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Gravity effects blood pressure by fluid-column effects
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pressure of blood increased in proportion to height of the blood in a column above it; this effect determines how high a heart can pump blood
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Flow rate is blank to changes in vessel radius than vessel length
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much more sensitive
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Circulation in birds and mammals is a
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closed circulatory system with vascular endothelial cells lining all blood vessels
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Systemic and pulmonary circuits are connected how?
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In series, with systemic being high pressure, pulmonary low pressure
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Arteries do what to pressure generated by heart?
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Dampen and Reserve pressure generated by heart, and transport blood long distances from heart; equipped with elastic walls with smooth muscle
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Arterioles are tiny arteries that control blood flow how?
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by vasomotor control to microcirculatory beds with densely distributed capillaries, where most gas exchange occurs
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Velocity and pressure drops in microcirculatory beds due to...
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large total cross sectional area; velocity picks back up again in veins
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Fluid is lost from systemic capillaries by...
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ultrafiltration, but lower pressures prevent this in the pulmonary system
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In birds and mammals, heart is...
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completely divided, systemic and pulmonary circulations in series with one another
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Microcirculatory beds consist of...
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arterioles, capillaries, and venules; flow controlled in arterioles; gas exchange mainly in capillaries
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Blood pressure BLANKS in terminal arteries, continues to BLANK until blood reaches veins
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drops in terminal arteries, continues to fall until it reaches veins
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What helps blood return to heart in veins?
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skeletal muscles and valves in the veins
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Ultrafiltration is
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an important consequence of a high pressure circulatory system, fluid is forced out of capillaries into tissues
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Fish heart
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pumps blood through two capillary beds, branchial and systemic
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Respiratory and systemic beds are BLANK for fish
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in series for fish, just as in birds and mammals
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Fish circulation: blood passes through two capillary beds...
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before returning to the heart; heart pumps blood through gills, then systemic circulation in series in most fish
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Farmer's View on lungs
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lungs are an adaptation for myocardial oxygenation
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Traditional View on lungs
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lungs are an adaptation for aquatic hypoxia
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Fish heart
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has four chambers in series
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Cephalopod molluscs and some annelids have BLANK circulatory systems
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CLOSED circulatory systems; same in series circulation of respiratory and systemic structures as birds and mammals, and have a heart for each
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Open Circulatory Systems (crustaceans)
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blood travels through lacunae, lacunar networks, and sinuses - which are spaces between cells that lack epithelial lining
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Open systems can have high blood flow rate, due to...
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low resistance compared to closed systems
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Cephalod circulation similar to...
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birds and mammals; left and right hearts of birds and mammals are analogous to systemic and branchial hearts
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In open systems, blood empties into...
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lacunae or sinuses between cells
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Insects meet gas exchange demands with?
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air-filled trachael systems; dorsal aorta only blood vessel, and it empties into lacunae
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