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33 Cards in this Set
- Front
- Back
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What are the two heart cell types?
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1)Autorhythmic: pacemaker cells, maintain rate ~1%
2)Contractile (myocardium): actually do mechanism of contraction ~99% |
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System Circulation
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Oxygenated blood moves from: left ventricle→aorta→arteries→arterioles→ capillaries→ venules→veins→inferior/superior vena cava which delivers blood directly into right atrium
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Capillary functions
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-delivery of oxygen and nutrients & removal of wastes
-thermoregulators dilate: warm, and to receive oxygen (more blood flow) constrict: cold, reducing loss of heat to environment |
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Name 4 valves and their location
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tricuspid: between right atrium and right ventricle
pulmonary: btwn right ventricle and pulmonary artery mitral (bicuspid): btwn left ventricle and left atrium aortic: between left ventricle and aorta |
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Heart valve anatomy and 2 functions
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Anatomy: Health valves are composed of leaflets or cusps that separate chambers of the heart
2 Functions: 1) unidirectional with blood flowing forward, preventing backflow 2) Facilitate generation of the pressure necessary to propel blood through circulation |
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Which is the only non-tricuspid valve in the heart?
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Mitral or "bicuspid valve" between the left ventricle and left atrium
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What happens to a heart valve if pressure of blood flow in forward direction and backward direction is equal?
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The valve is in its NATIVE, CLOSED position
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Pulmonary Circulation
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Deoxygenated blood moves from: right ventricle→ pulmonary trunk→divides into 2 right/left pulmonary arteries→gas exchange in right/left lung alveoli capillary beds→venules→4 left/right pulmonary veins → left atrium
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Pulmonary and systemic circulation comprise one continuous circulation. (T/F)
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True. Pulmonary and systemic circulation constitute two components of a continuous loop.
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Each lung has one pulmonary artery and one pulmonary vein. (T/F)
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False. There are 2 pulmonary veins per lung.
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Name steps of heart contraction in diastole and systole
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Diastole:
1a) Chambers relaxed, low pressure, allowing blood from system circulation to rush in right/left atrium (most blood flows directly into ventricles) 1b) Atrial contraction, semilunar valves are closed, forcing blood into ventricles Systole: 2) Ventricular contraction forcing blood into system and pulmonary circulation; atrioventricular valves closed |
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Heart Pump Contraction: Diastole and Systole
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Diastole- atria: are relaxed, then contracted
ventricles: relaxed throughout diastole Systole: contraction of two ventricles |
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Sinoatrial (SA) node
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-Heart's natural pacemaker located in the upper right atrium (near opening of sup. vena cava)
-initiates intrinsic, regular, rhythmic emission of contractile signals at 120 impulses/min -receives nerve supply from both sympathetic and parasympathetic (vagus nerve) |
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If the heart's SA node initiates 120 impulses/min, why do we have a slower heart rate?
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Because the vagus nerve from the parasympathetic nervous system innervates the SA node to produce a resting heart rate of 50-75 impulses/min.
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Pathway of impulse signal
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SA node (upper right atrium) → AV node (interatrial septa, up near intersection of 4 heart chambers) → bundle of His (myocardial fibers along septum btwn ventricles)→ Purkinje fibers spread through bottom of ventricles (provide force for ventricular contraction, "systole")
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Which have thinner walls, atria or ventricles?
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Atria
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Which have thick, muscular walls, atria or ventricles?
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Ventricles
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What is different about the pulmonary arteries compared to others?
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transport DEOXYGENATED blood away from the heart, to the lungs
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How do large veins in legs prevent back flow caused by gravity?
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They have valves
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Since there is low blood pressure in veins, what are mechanisms that allow return of blood to heart?
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-Muscle contraction.
-Decreased venous compliance. Sympathetic activation of veins decreases venous compliance, increases central venous pressure and promotes venous return indirectly by augmenting cardiac output through the Frank-Starling mechanism, which increases the total blood flow through the circulatory system. -Respiratory activity. During respiratory inspiration, the venous return increases because of a decrease in right atrial pressure. -Gravity. |
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blood pressure is lowest in the ____ and highest in the ____ when the ventricles contract.
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blood pressure is lowest in the VEINS, and highest in the ARTERIES when the ventricles contract.
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what is normal blood pressure?
what is 120 in normal blood pressure? what is 80 in normal blood pressure? |
-120/80
-systolic number = pressure when the ventricles contract -diastolic number = pressure when heart relaxes (and atrial contraction) |
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What does the vagus nerve do?
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-Innervates the heart and digestive system.
-Slows the rate of heart contractions and increases digestive activity in the intestines |
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How do the impulses travel from the SA node?
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Through electrical synapses made from gap junctions
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Structure of arteries
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-Elastic and stretch when filled with blood
-Contain most smooth muscle. |
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Medium size arteries contain more smooth muscle than larger arteries.
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True. More efficient in rerouting blood.
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Name 4 methods for materials to cross capillary vessels:
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1) pinocytosis
2) diffusion or transport through capillary cell membranes 3) movement through pores in the cells called fenestrations 4) movement through the space between the cells |
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List blood vessels in descending order based on: cross-sectional area, velocity, and blood pressure.
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Cross-sectional area: Capillaries>veins>arteries
Velocity: arteries>veins>capillaries Blood Pressure: Systemic arteries (some capillaries)> pulmonary arteries> systemic capillaries> pulmonary capillaries and veins> systemic veins |
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Blood pressure
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(arterial blood pressure), pressure exerted by circulating blood upon the walls of blood vessels
-increases near the heart and decreases to its lowest in the capillaries |
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Velocity and cross-sectional area follow which equation
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continuity equation, Q=Av (blood flow)
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How do pressures create fluid exchange in capillaries?
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As blood flows into capillary (arterial end):
-hydrostatic pressure>osmotic pressure →net fluid flow is out of capillary & into interstitium As blood flows out of capillary (venule end): -osmotic pressure>hydrostatic pressure →net fluid flow is out of interstitium & into capillary |
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What is the net result of fluid exchange by the capillaries from aterial to venule end?
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10% loss of fluid to interstitium
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Contrasts between arteries and veins.
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VEINS ARTERIES
Blood Volume (64%) Blood Volume (15%) Valves No Valves Larger diameter Smaller diameter Thinner walls Thicker walls |
