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The Cardiovascular System: The Heart
Brady Anatomy and Physiology for Emergency Care 2nd Edition Chapter 11
64
Anatomy
Professional
02/16/2012

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Term
2 circuits of the blood vessels
Definition
-Pulmonary circuit
-carries blood to and from the exchange surfaces of the lungs
-Systemic circuit
-transports blood to and from the rest of the body
-Each circuit begins and ends at the heart.
Term
Arteries
Definition
-Efferent vessels
-carry blood away from the heart
-highly muscular
Term
Veins
Definition
-Afferent vessels
-return blood to the heart
Term
Capillaries
Definition
-small thin walled vessels between the smallest arteries and the smallest veins.
-thin wall allows for exchange of nutrients, dissolved gases, and waste products between the blood and surrounding tissue.
Term
Chambers of the heart
Definition
-Heart has 4 chambers
-Right Atrium
-receives blood from the systemic circuit
-Right Ventricle
-discharges blood into the pulmonary circuit
-Left Atrium
-collects blood from the pulmonary circuit
-Left Ventricle
-ejects blood into the systemic circuit.
Term
Pericardium
Definition
-lining of the pericardial cavity
-serous membrane
-visceral pericardium covers the outer surface of the heart (epicardium)
-parietal pericardium lines the inner surface of the pericardial sac.
-Normally contains small amount of pericardial fluid secreted by pericardial membrane that acts as lubricant
Term
Coronary sulcus
Definition
-deep groove usually filled with fat, marks the border between the atrial and ventricles.
Term
Anterior interventricular sulcus and posterior interventricular sulcus
Definition
-smaller fat filled grooves that mark the boundary between the left and right ventricles
Term
Heart wall
Definition
-3 distinct layers
-Epicardium
-covers the outer surface of the heart
-serous membrane attached to the myocardium
-Myocardium
-muscular wall of the heart
-contains cardiac muscle tissue, blood vessels and nerves
-concentric layers wrap around atria and spiral into the walls of the ventricles, this causes the squeezing/twisting contractions of the heart.
-Endocardium
-simple squamous epithelium, inside layer
Term
Interatrial septum
Definition
-separates the two atria
Term
Interventricular septum
Definition
-separates the two ventricles
Term
Atrioventricular valve
Definition
-where each atrium opens into the ventricle on the same side.
-comprised of fibrous tissue to ensure one way blood flow from atria to ventricle.
Term
Superior vena cava
Definition
-delivers blood to the right atrium from the head, neck, upper limbs and chest.
Term
Inferior vena cava
Definition
-delivers blood to the right atrium from the trunk, viscera and the lower limbs.
Term
Coronary sinus
Definition
-opens into the right atrium slightly below the connection with the inferior vena cava.
-returns venous blood from the cardiac veins
Term
Foramen ovale
Definition
-allowed blood to flow from the right atrium to the left atrium while the lungs were developing
-closes after 48 hours after birth.
Term
Right atrioventricular valve
Definition
-fibrous tissue vavle allowing for one way flow from the right atrium into the right ventricle.
-3 flaps called cusps
-known as the tricuspid valve
Term
Chordae tendineae and papillary muscles
Definition
-CT are fibers that connect to PM (cone shaped projections on the inner surface of the ventricles) to form the AV's.
-Prevent backflow
Term
Pulmonary trunk, pulmonary semilunar valve, left & right pulmonary arteries and left & right pulmonary veins
Definition
-start of the pulmonary circuit
-blood flows from the right ventricle past the PSV into the PT and into the left and right pulmonary arteries that branch repeatedly in the lungs down to capillaries where gases are exchanged.
-From the respiratory capillaries the blood flows into the left and right pulmonary veins, which deliver it to the left atrium.
Term
Left atrioventricular valve
Definition
-bicuspid valve
-same as RAV, allows for flow of blood from the left atrium to the left ventricle and prevents backflow.
-"Mitral" valve.
Term
Aorta and aortic semilunar valve
Definition
-Blood leaves the left ventricle and passes through the aortic semilunar valve and into the aorta, which is the start of the systemic system.
Term
Difference between left and right ventricles
Definition
-RV does not need to push as hard to create blood flow since lungs are close to heart and veins are short and wide.
-RV wall is relatively thin.
-Contraction of the RV is efficient but develops low pressure
-Systemic circuit requires 6-7 times more force than pulmonary circuit.
-LV has extremely thick muscular wall
-2 things happen when LV contracts
-distance between base and apex decreases
-diameter of the ventricular chamber decreases
-LV bulges into RV when it contracts, also helps blood leave RV.
Term
Aortic sinuses
Definition
-sac-like expansions of the base of the ascending aorta next to the cusp of the aortic semilunar valve that prevent cusps from sticking to the wall of the aorta when the valve opens.
-Right and left coronary arteries originate at the aortic sinuses.
Term
Coronary circulation
Definition
-supplies blood to the muscle tissue
Term
Coronary arteries
Definition
-originate at the aortic sinuses
-BP here is the highest in the systemic circuit.
-Ensures continuous blood flow to cardiac muscle.
Term
Right coronary artery
Definition
-supplies blood to the right atrium and portions of both ventricles.
Term
Left coronary artery
Definition
-supplies blood to the left ventricle, left atrium and interventricular septum
Term
Marginal and posterior interventricular (descending) branches
Definition
-formed by the RCA
Term
Circumflex and anterior interventricular (descending) branches
Definition
-formed by the LCA
Term
Great and middle cardiac veins
Definition
-carry blood away from the coronary capillaries
Term
Coronary sinus
Definition
-where the great and middle coronary veins drain into
-large thin walled posterior portion of the coronary sulcus.
-opens into the right atrium near the base of the inferior vena cava.
Term
Infarct
Definition
-an area of dead tissue caused by an interruption in blood flow
Term
Myocardial infarction
Definition
-MI (heart attack)
-coronary circulation becomes blocked and cardiac muscle cells die from a lack of oxygen.
-most often a result of severe coronary artery disease
-buildup of fatty deposits in the walls of the coronary arteries.
Term
Heartbeat
Definition
-created by contractions of individual cardiac muscle cells in the atria and ventricles.
-2 types of cells: contractile and cells of the conducting system
-contractile cells produce powerful contractions that propel blood
-cells of the conducting system are non-contractile and control and coordinate the activities of the contractile cells.
Term
Automaticity (autorhythmicity)
Definition
-Cardiac muscle tissue contracts on its own in the absence of neural and hormonal stimulation
Term
Heart contraction sequence
Definition
-Atria contract first, followed by the ventricles
Term
Heart's conducting system
Definition
-specialized cardiac muscle cells initiate and distribute electrical impulses.
-2 types of cells that do not contract: nodal and conducting cells
-Action potential created in the nodal cells and sweeps through conducting system, reaching all of the cardiac muscle tissue and causing a coordinated contraction.
Term
Nodal cells
Definition
-nodal cells: establish rate of cardiac contraction, located at the SA (sinoatrial) and AV (atrioventricular) nodes
-depolarize spontaneously and generate action potentials at regular intervals
Term
SA Node
Definition
-Sinoatrial node
-posterior wall of the right atrium near the entrance of the superior vena cava.
-depolarizes rapidly and spontaneously
-70-80 beats per minute
Term
AV node
Definition
-Atrioventricular node
-located in the floor of the right atrium near the coronary sinus
-cells of the SA node electrically connected to the AV node by conducting cells in the atrial walls
-Also depolarizes spontaneously 40-60 beats per minute.
-AV node usually only fires after action potential from SA node, but if it does not receive that AP it fires on its own.
-slows the impulse down before reaching the AV bundle to allow for the atria to contract and fill the ventricles before the ventricles fire.
Term
AV bundle and bundle branches
Definition
-aka bundle of His
-bundle of collecting cells that receives AP from AV node, extends along the interventricular septum then divides into the left and right bundle branches which radiate across the inner surfaces of the left and right ventricles.
Term
Purkinje fibers
Definition
-convey impulses to the contractile cells of the ventricular myocardium
Term
Bradycardia
Definition
-heart rate slower than 60bpm
Term
Tachycardia
Definition
-heart rate faster than 100bpm
Term
Ectopic pacemaker
Definition
-cases in which abnormal conducting cells or ventricular muscle cells generate APs so rapidly that they override the SA or AV nodes, thus bypassing the regular system and disrupting the timing of ventricular contractions.
Term
Electrocardiogram (ECG/EKG)
Definition
-recoding device of electrical events of the body
Term
P wave
Definition
-accompanies the depolarization of the atria on EKG.
-atria begin contracting 100msec after start of P wave
Term
QRS complex
Definition
-appears as the ventricles depolarize.
-electrical activity relatively strong due to the mass of the ventricular muscle being larger than that of the atria.
Term
T wave
Definition
-fuck it.
-indicates ventricular repolarization
Term
Cardiac arrythmias
Definition
-abnormal patterns of cardiac activity
-clinical problems arise when the arrythmias reduce the heart's pumping efficiency
-serious arrythmias can be indicative of damage to the myocardium, injuries to the pacemaker or conduction pathways, exposure to drugs, or variations in the electrolyte composition of the extracellular fluid.
Term
Cardiac cycle
Definition
-period between the start of one heartbeat and the start of the next
-fluids move from an area of high pressure to low pressure.
-during CC, pressure in each chamber rises during systole and falls during diastole. Increased pressure in one chamber causes blood to flow to another chamber (or vessel) of lower pressure
Term
Systole
Definition
-contraction
Term
Diastole
Definition
-relaxation
Term
Heart sounds
Definition
-"Lubb"
-produced as the AV valves close and the semilunar valves open.
-marks the start of ventricular systole

-"Dubb"
-occurs at the beginning of ventricular diastole, when the semilunar valves close.

-Third and fourth heart sounds may be audible as well but are very faint
Term
Stroke volume
Definition
-SV
-amount of blood ejected by a ventricle during a single heartbeat
Term
Cardiac output
Definition
CO = SV x HR
-the amount of blood pumped by each ventricle in one minute.
-provides an indication of the blood flow through peripheral tissues
Term
Factors that control cardiac output
Definition
-Primary
-blood volume reflexes
-autonomic innervation
-hormones
-Secondary
-concentration of ions in the extracellular fluid
Term
Atrial reflex
Definition
-affects the heart rate
-adjusts the heart rate in response to the venous return of blood to the right atrium.
-entry of blood flow stimulates stretch receptors in the right atrial walls and triggers a reflexive increase in the HR through increased sympathetic activity, as a result SA node depolarize faster
Term
Filling time
Definition
-duration of ventricular diastole when blood can flow into the ventricles
-depends on HR; faster the HR, slower the filling time and the opposite
Term
Frank-Starling principle
Definition
-"more in = more out" rule
-the myocardium stretches farther, the ventricles produce greater force upon contraction and stroke volume increases
Term
ANS Innervation
Definition
-both sympathetic and parasympathetic systems innervate the heart
-primarily reflect the responses of the SA node to acetylcholine and norepinephrine.
Term
Acetylcholine effects on heart and stroke volume
Definition
-released by the parasympathetic motor neurons results in a lowering of the HR.
-results in decreased force of cardiac contractions, greatest reduction is in the atria due to limited parasympathetic innervation of the ventricles
Term
Epinephrine and norepinephrine innervations of the heart
Definition
-NE increases the heart rate, released by the sympathetic nervous system.
-a more sustained increase in HR results from release of E and NE by the adrenal medullae during sympathetic activation
-stimulate cardiac muscle cell metabolism and increases force and degree of contraction, resulting in increased SV.
Term
Cardioacceleratory and cardioinhibitory centers
Definition
-located in the medulla oblongata
-cardioacceleratory center activates sympathetic motor neurons
-cardioinhibitory center controls parasympathetic motor neurons
-respond to changes in BP and atrial concentrations of dissolved oxygen and CO2.
-monitored by baroreceptors and chemoreceptors
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