Ch. 18 The Heart Flashcards
Pericardium
Superficial layer
1. fibrous pericardium: connective tissues, protective
2. Serous pericardium: serosa
a. parietal layer: deep to fibrous pericardium
b. pericardial cavity: filled with lubricating serous fluid
c. viseral layer: surrounds the heart itself (epicardium)
Layers of the Heart wall
Superficial to deep
1. Epicardium: helps reduce friction
2. Myocardium: composed of cardiac muscle-arranged in function synctitia
3. Endocardium: inner lining, flexible and elastic
Gross Cardiac Anatomy: Chambers and associated blood vessels
Atria: receiving chambers
1. Pectinate muscles: atria wall muscles (contracts atria), comb-like
right atrium: recieves deoxygenated blood from the body
recieves via: superior (superior body parts) and inferior (inferior body parts)
vena cava, and coronary sinus (blood from myocardium)
sends blood to the right ventricle through the tricuspid valve
Interatrial septum: anatomical wall seperating L and R atrium
Fossa Ovalis: R atrium; used to be a forman ovalis as a fetus
Left Atrium: Recieves oxygenated blood from the Lungs via 4 pulmonary veins, sends to the L ventricle via the bicuspid/mitral valve
Ventricles: ejecting chambers
1. Trabeculae carneae: ventricular wall muscles, thicker, stronger to pump out blood
2. papillary muscles: nipple-shaped, anchors for the chordae tendineae
3. chordae tendineae: cords that pull valves open
R ventricle: pulmonary circuit pump; receives blood from R atrium
sends blood to pulmonary trunk–>pulmonary arteries—> lungs via the
pulmonary valve
Interventricular septum: anatomical wall separating L and R ventricles
L Ventricle: systemic circuit pump; receives blood from the L atrium sending the blood out the aorta to the rest of the body via the aortic valve
The Heart Valve (AV and SL)
AV- Atriocentricular Valves
1. Right AV: tricuspid valve
2. Left AV: bicuspid/mitral valve
when ventricles relax: AV valve opens- allows blood flow
when ventricles contract: AV valve shut
SL- Semilumar Valves
1. Right SL: pulmonary valve
2. Left SL: aortic valve
when ventricles relax: SL valve shuts
when ventricles contract: SL valve opens
AV and SL take turns working to create appropriate blood flow and prevents back flow
Coronary Circulation
Coronary arteries: supply blood to the myocardium
R coronary:
1. marginal
2. posterior interventricular
L coronary:
1.circumflex
2. anterior interventicular
Cardiac Veins
function: drain the myocardium
2. great cardiac
3. Middle cardiac
4. small cardiac
5. coronary sinus: delivers blood back to the right atrium
Microscopic cardiac anatomy
cardiac tissue characteristics:
1. branched
2. striated
3. have intercalated discs
desosomes: protein linkers that “zip” cells together, resists mechanical stress
gap junctions: protein channels used for rapid communication
Cardiac Physiology: Contractions and Action Potentials
- the heart is composed of two types of cells:
typical myocardium: contractile
autorythmic cells: self-depolarizing
Electrophysiology Review: Resting Membrane Potential
- At rest: Na=K pump creates electrochemical gradient/difference. More Na+ outside vs. more K+ inside cells
- Upon receiving threshold stimuli, membranes will deplorize as result of the movement of the ions
- In addition to the Na+ and K+, Ca2+ is an ion needed by muscles to signal contraction. these ions are crucial to the physiology of the heart.
Cardiac Muscle Action Potentials
- Cardiac muscles will contract similar to skeletal muscle tissue (sliding filament model)
- difference:
a. stimuli: heart doesn’t need brain to contract (involuntary movement), stimuli is
autorythmic cells
b. refractory period: longer than skeletal muscles to avoid tetanic contractions
(elongated/irregular) - When cardiac muscle cells receive threshold stimuli, they’ll react by:
a. depolarize: rapid Na+ influx in the cell, is caused voltage increase
b. Plateau: Ca2+ influx into cell
c. repolarize: K+ influx out of cell
Pacemaker and Autorythmic Cell Action Potentials
A. autorythmic cells: small clusters of specialized, non-contractile cells that generate their own action potentials
B. Since they create their own action potentials, they are the source of stimuli for the cardiac muscle cells and not nervous system. the APs coming from these cells will trigger cardiac muscle contractions. These clusters of cells work together to create basal/resting heart rates.
C. The APs created by these celled show a pattern.
1. slow depolarization: “pacemaker potential” Na+ influx (into cell)
2. Depolarization: Ca2+ influx (into cell)
3. Repolarization: K+ influx (out of cell)
Cardiac Conduction System
the heart relies on a conduction system. “electrical wiring” to spread electrical signal.
1. SA node- Sinoatrial/Pacemaker: autorythmic cells in R atrium, generates own APs, causing atria to contract
2. AV nodes- Atrioventricular: cluster of autorythmic cells that will send APs down the
a. bundle of His
b. L and R Bundle Branches
c. Purkinje Fibers
Results: ventricular depolarization/contractions
SA Node depolarizes —> atria contracts
AV Node depolarizes —> ventricles contract
Cardiac Innervation
Although SA node sets the basal pacing of heart beats, the autonomic nervous system can influence whether the SA nodes depolarizes rapidly or slowly.
1. cardioacceleration: sympathetic (fight-or-flight) causes increased rate of depolarization, increased contractility, dialetes coronary arteries/allows blood flow
2. cardioinhibition: parasympathetic mode, decreased rate of depolarization
Recording cardiac electrical activity: EKG
Function: monitor electrical changes that accompany each cardiac cycle
P-wave: atria depolarizes (SA node is working) contracts
QRS-complex: ventricles depolarize/contract (AV node is working)
F-wave: ventricles repolarize/relax
Auscultations: Heart Sounds
Sounds caused by the 4 chambers/valves
“lub-dup” pause “lub-dup”
1. “lub”/S1- when the AV valves close
a. tricuspid valve: best ausculated on lower margin of sternum, 4th intercostal space
b. bicuspid valve: best ausculated on 5th intercostal space, midclavicular line
2. "dup"/S2- when the SL valve close
a. pulmonary valve: best ausculated on upper left margin of sternum
b. aortic valve: best ausculated on upper right margin of sternum
3. Pause- quiescent period
