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149 Cards in this Set
- Front
- Back
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What are some similarities between skeletal muscle and cardiac muscle?
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Both are striated fibers that contract by sliding thin filaments
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In skeletal muscle, myofibrils have what kind of diameters?
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Uniform Diameters
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In cardiac muscle, myofibrils have what kind of diameters?
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Irregular diameters
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Skeletal muscle contractions range from what?
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Twitches to sustained tetanic contractions
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Can you tetanize cardiac muscle?
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NO. NO. NO!
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In skeletal muscles, the calcium needed is where?
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Stored in the SR
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In cardiac muscle, the calcium needed is where?
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Some is in the SR but also in the extracellular fluid
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What is the only job of the heart?
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To pump blood
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What is the only type of contraction of the heart?
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slow muscle twitch
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Are cardiac muscle cells are dependent or independent?
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Independent!
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Cardiac muscle cells physically interconnect via what?
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Gap junctions
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What do gap junctions allow?
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gap junctions allow APs to spread from cell to cell
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The atria are what? What do they do?
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Small, not very muscular chambers that contract only to complete the filling of the ventricles
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What is the name of the valve that connects the Right Atrium to the Right Ventricle?
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Tricuspid Valve
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What is the name of the valve that connects the Left Atrium to the Left Ventricle?
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Mitral or Bicuspid valve
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Ventricles are what? What do they do?
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Ventricles are much more muscular chambers that contract to generate pressure to eject blood away from the heart
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Why is the Right Ventricle not as muscular as the Left Ventricle?
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It's not as muscular because it's only sending deoxygenated blood to the lungs
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Why is the Left Ventricle the most muscular ventricle?
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Because it must propel all the oxygenated blood into the body
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Which ventricle is the most muscular?
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Left Ventricle!
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When taking blood pressure, what is being read?
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The pressure from the Left Ventricle
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Which side of the heart is the pump for the pulmonary circuit?
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Right side (RA and RV)
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Which side of the heart is the pump for the systemic circuit?
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Left side (LA and LV)
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Blood is first pumped into which side of the heart?
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Right side
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Where does gas exchange occur?
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Inside the capillary beds of all body tissues
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What is the pulmonary circuit?
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Blood enters the right side of the heart, then to the lungs, then to the left side of the heart
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What is the purpose of the pulmonary circuit?
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To oxygenate the blood
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What is the systemic circuit?
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Blood is pumped into the left side of the heart, then to the body, then to the right side of the heart
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What is the purpose of the systemic circuit?
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Allows oxygenated blood to be delivered to the tissue cells
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Both atria contract in what?
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Unison!
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Both ventricles contract in what?
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Unison!
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What is the volume of blood traveling each circuit?
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The volume of blood traveling in each circuit should be the same at all times
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What are the four main blood vessels that attach to the heart?
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1. Superior and Inferior venae cavae
2. Pulmonary Trunk (which become the pulmonary arteries) 3. Pulmonary veins 4. Aorta |
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What are the purpose of the Superior and Inferior Venae Cavae?
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They return deoxygenated blood to the Right Atrium
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Arteries carry blood away or toward the heart?
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AWAY FROM THE HEART
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Superior and Inferior Venae Cavae are also called what?
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"Cavernous Veins"
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What kind of blood does the pulmonary trunk receive?
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Deoxygenated blood ejected from the Right Atrium
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The Pulmonary Trunk divides into what? What do they do?
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The Right and Left Pulmonary Arteries which carry deoxygenated blood away from the heart to the lungs
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What do the Pulmonary Arteries divide into?
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Pulmonary capillaries which surround the alveoli
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What are the alveoli?
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Alveoli are air-filled sacks which allows oxygen to diffuse easily into the blood stream
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The oxygenated blood returns to the heart via what?
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The Pulmonary Veins
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Veins carry blood in what direction?
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Veins carry blood TOWARD the heart
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Oxygenated blood goes where after going through the lungs?
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Left Atrium
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After being in the Left Atrium, oxygenated blood goes where?
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Left Ventricle
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What does the Left Ventricle do?
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Ejects oxygenated blood to the rest of the body via the aorta
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What do heart valves ensure?
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They ensure one-way blood flow through the heart
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What are Atrioventricular Valves?
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They are valves that separate the atria from the ventricles
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What are Semilunar Valves?
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They are valves that separate each ventricle from the blood vessel it ejects into
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Valves open or close do to what?
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Pressure differences as heart chambers contract or relax
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What is Systole?
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Systole is the contraction of a chamber
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What is Diastole?
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Diastole is the relaxation of a chamber
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The Mitral or Bicuspid valve has how many cusps?
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2!
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The Tricuspid valve has how many cusps?
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3!
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Why is it called the Mitral Valve?
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Because it looks like the Bishop or Pope's hat (a Mitar)
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AV valves are anchored by what?
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Chordae Tendineae
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What do Chordae Tendineae keep the cusps from doing?
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They keep the cusps from inverting during ventricular systole
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When are the AV valves open? Are the ventricles contracted or relaxed
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AV valves are open during VENTRICULAR DIASTOLE when the ventricles are RELAXED and filling with blood
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When are the AV valves closed?
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AV valves close at the BEGINNING OF VENTRICULAR SYSTOLE when the ventricles CONTRACT
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Closure of the AV valves is associated with what sound?
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Lub
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Lub is the first or second sound associated with the heart?
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1st sound
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When AV valves are open, atrial pressure is greater or lesser than ventricular pressure?
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GREATER THAN
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When AV valves are closed, atrial pressure is less than or greater than ventricular pressure?
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LESS THAN
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What is the Aortic Semilunar Valve?
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It is the valve that separates LV from the aorta
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What is the Pulmonary Semilunar Valve?
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It is the valve that separates the RV from the pulmonary trunk that divides into the Pulmonary Arteries
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When are the Semilunar valves open?
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Forced open at the BEGINNING OF VENTRICULAR SYSTOLE when ventricles contract
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When do the Semilunar Valves close?
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Close at the BEGINNING OF VENTRICULAR DIASTOLE when the ventricles begin to relax
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Dup is the associated sound with what?
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The closure of the SL valves is the second heart sound
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Why don't the Semilunar Valves have chordae tendineae?
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Because they're not under the same pressure as the AV valves
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What is the pathway of blood through the Aorta?
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Aorta -> Systemic circulation -> Venae cavae -> Right Atrium
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What is the pathway of blood through the Left Atrium?
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Left Atrium -> Bicuspid Valve -> Left Ventricle -> Aortic Semilunar Valve -> Aorta -> Systemic Circulation -> Venae Cavae -> Right Atrium
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True or False: The heart can beat on its own without nerves.
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TRUE!
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Cardiac cells are physically WHAT and electrically WHAT?
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Physically interconnected and Electrically Coupled
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Autorythmic cells spontaneously what?
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Autorythmic cells spontaneously set off APs
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What are Intercalated Discs?
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Intercalated Discs are junctions that interconnect the cardiac cells
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What are desmosomes?
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Desmosomes are the "rivets" that hold the cardiac cells tegether
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What are gap junctions?
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Gap junctions are interspersed throughout sarcomere that allow ions to pass from cell to cell and APs to spread quickly
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What is a difference between Neuromuscular Junctions and Gap Junctions?
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Neuron and muscle cells do not touch while cardiac cells DO touch.
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Are NTs released in Gap Junctions?
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NO!
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What spreads AP cell to cell in cardiac muscle?
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Gap Junctions
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What are 4 advantages of Gap Junctions?
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1. APs spread quickly
2. Faster than releasing NT 3. Heart cells contract almost in unison 4. Heart acts as a functional syncytium (that is, in synchronicity) |
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What makes up 99% of the cardiac muscle cells?
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Contractile Cells
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What do Contractile Cells do?
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They contract; they carry out pumping action
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Do Contractile Cells spontaneously fire APs?
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NO.
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What makes up 1% of cardiac muscle cells?
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Autorythmic cells
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What do Autorythmic Cells do?
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Autorythmic cells DO NOT contract, they spontaneously fire APs that spread via Gap Junctions
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Autorythmic Cells are localized along what pathway?
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Intrinsic Conduction System
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What does the Intrinsic Conduction System do?
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It coordinates contraction of the heart chambers
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Autorythmic Cells coordinate what?
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Coordinate electrical activity of the heart
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Cells in the sino-atrial note are what?
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The pacemaker of the heart
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What is important about the pacemaker or SA node?
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It depolarizes the fastest (70 times/min)
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What sets off APs in the heart?
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The Sinoatrial Node
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APs spread to what node after being set off by the Sinoatrial Node?
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APs spread to the Atrioventricular (AV) node
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When the APs spread to the AV node, what occurs?
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APs slowed down to let the Atria relax
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Atria and Ventricles are electrically what from each other?
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Electrically Separated from each other
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Can APs travels along different paths?
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NO.
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What if the conduction system is blocked? Do the ventricles stop beating?
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No, the next fastest autorythmic cells become the new pacemaker
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Contractile Cardiac Cells have what kind of voltage-gated channels?
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Na+, K+, and Ca2+
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When do the Ca+ channels open during Contractile Cardiac Cell AP?
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During the plateauing phase
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What are the 2 purposes of the opening of Ca2+ channels?
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1. Extracellular Ca2+ supplements Ca2+ released from the SR
2. Prolongs the AP |
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Why is calcium needed by the heart?
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Calcium is needed to activate the thin filaments
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Why can't the heart be tetanized?
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Due to the long (200 ms) absolute refractory period
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By the time the 2nd AP can fire, what has nearly relaxed?
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The muscle
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What part of the AP sets off contraction?
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Depolarization
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What part of the AP allows relaxation?
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Repolarization
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What is an electrocardiogram?
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It measures APs in the whole heart at a given time
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What are the 3 waves of the ECG?
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P wave, QRS complex, T wave
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From what waves makes a complete cardiac cycle?
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P wave to P wave
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What is the P Wave?
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The P Wave is the atrial depolarization
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What is the QRS complex?
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Ventricular Depolarization
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What is the T Wave?
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Ventricular Repolarization
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When does Atrial Repolarization occur?
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Sometime during the QRS complex
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During the P wave, what is occurring? Where is it initiated?
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Atrial depolarization initiated at the SA node
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During the P wave, what is occurring in the ventricles?
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They are filling up
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Impulse is then WHAT at the AV node?
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Delayed!
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What does ventricular depolarization cause?
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Causes QRS complex
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During the QRS complex, what is occurring in the ventricles?
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Ventricles contract and the Atria repolarize and relax
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Right after the QRS complex, what is occurring?
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Ventricles remain depolarized and contracted
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During the T Wave, what is occurring?
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Ventricular repolarization begins which triggers T wave and ventricles relax
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After the T Wave, what has occurred?
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Ventricles are relaxed, cycle is ready to restart
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During mid diastole, aka before the P wave, are the Atria contracting or relaxing?
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Relaxing!
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During mid diastole, aka before the P wave, are the vesicles contracting or relaxing?
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Relaxing!
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Late Diastole, aka P wave, are the atria contracting or relaxing?
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Contracting!
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Late Diastole, aka P wave, are the ventricles contracting or relaxing? Filling or Emptying?
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Relaxing! Filling!
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During late diastole, aka P wave, is sound being heard?
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NO
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During the Beginning of Ventricular Systole (isovolumetric contraction), aka QRS complex, are Atria contracting or relaxing?
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Relaxing!
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During the Beginning of Ventricular Systole (Isovolumetric contraction), aka QRS complex, are ventricles contracting or relaxing?
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Contracting!
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During the beginning of Ventricular Systole, are AV valves open or closed?
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Closed!
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During the beginning of Ventricular Systole, are SL valves open or closed?
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Closed!
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What sound is heard during Ventricular Systole? What is the sound due to?
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Lub is heard when the AV valves close
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At what time are all four valves closed?
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Ventricular Systole and Diastole
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During late Ventricular Systole, AV valves are WHAT and SL valves are forced to WHAT?
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AV valves are closed and SL valves are forced open
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During late Ventricular Systole, the ventricles are doing what?
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Ejecting blood!
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What is ESV?
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End Systolic Volume
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What is the Stroke Volume?
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EDV - ESV
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When the ventricles eject the blood, the ventricle reaches what?
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End Systolic Volume
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During early diastole, aka T wave, ventricles are beginning to what?
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Beginning to relax
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During early diastole, aka T wave, AV valves are open or closed?
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AV valves are still closed
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During early diastole, aka T wave, SL valves are open or closed?
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Closed!
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Dup is heard when what valves close?
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SL valves
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During early diastole, are Atria relaxing or contracting?
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Relaxing!
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During early diastole, are ventricles relaxing or contracting?
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Relaxing!
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As the pressure drops during early diastole, what are opening?
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The AV valves are opening
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What kind of motor neurons innervate the heart?
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Parasympathetic and sympathetic autonomic motor neurons
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Sympathetic nerves cause what kind of response?
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Fight or flight response
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Sympathetic nerves have what 2 effects on the heart?
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1. Increase heart rate
2. Increase contraction strength |
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Sympathetic nerves release what NT?
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Norepinephrine (NE)
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When sympathetic nerves secrete NE, what two things occur?
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1. NE stimulates SA and AV nodes and the heart beats faster
2. Stimulates ventricular cells and strengthens contraction |
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Parasympathetic nerves secrete what NT?
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ACh
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When parasympathetic nerves secrete ACh, what occurs?
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ACh inhibits SA and AV nodes which slows down the heart
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Parasympathetic nerves slow down the heart via what nerve?
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The Vagus nerve
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