Term
Number of Chambers in The Heart
-Atria
-Ventricles |
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Definition
4 chambers
2 Atria
2 Ventricles |
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Term
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Definition
| Interatrial and Interventricular |
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Term
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Definition
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Term
| Where are cardiac muscles found? |
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Definition
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Term
| Types and % of Cardiac Muscle cells |
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Definition
1. Contractile (99%)
2. Auto-ryhthmic (1%) |
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Term
| Size of Contractile Cells |
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Definition
| Smaller than skeletal, often branch |
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Term
| Do they have thick and thin filaments? |
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Definition
| Yes, they are arranged into sarcomeres and is also striated |
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Term
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Definition
similar to skeletal muscle except--
-AP traveling across surface of membrance and down T tubules cause Voltage gated ca channels in the membrance to open and ca enters the cells from the ECF |
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Term
| Ca entering from ECF causes |
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Definition
| The ca channels on SR to open, known as Ca induced, calcium release from SR |
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Term
| Which Calcium (from ECF or SR) binds to troponin? |
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Definition
| Ca from SR binds to troponin and the contraction occurs like skeletal |
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Term
| Is Ca released from SR by AP in T tubules? |
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Definition
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Term
| Relaxaction of Cardiac Muscle |
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Definition
Removal of Ca from cytosol allows troponin and tropomyosin to return to covering myosin binding site on actin. Ca removed by:
-Ca ATPase in SR
-Ca ATPase in plasma membrane
- Na-Ca exchanger in plasma membrane |
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Term
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Definition
| A drug that decreases heart contraction strength by increasing intercellular calcium by decreasing Na-Ca exchange. More Ca remains in cells. |
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Term
| How are Contractile Cells connected |
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Definition
| They are all connected to one another by gap junctions |
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Term
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Definition
| Areas of contact between cells with a high concentration of gap junctions which allows for the spread of action potentials between cells. Contract as a unit. |
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Term
| How many demosomes, which do what? |
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Definition
| A large number, resist stress of beating. |
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Term
| Contractile Cell metabolism- |
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Definition
| Oxidative (aerobic) metabolism |
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Term
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Definition
| No cell division after infancy, growth by hypertrophy (increased cell size, exercise) |
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Term
| When cells die (heart attack) when are they replaced? |
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Definition
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Term
| Function of Contractile Cells: |
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Definition
Rythmic contraction and relaxation generates heart pumping action.
Contraction pushes blood out of heart
relaxation allows heart to fill with blodd. |
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Term
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Definition
| initiate and propogate the AP responsible for contraction of the contractile cells |
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Term
| Very few myofilaments in Autorythmic cells mean- |
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Definition
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Term
| Types of Autorythmic Cells: |
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Definition
Pacemaker Cells: Initiate AP
Conducting Cells: Propagate AP |
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Term
| Where are Pacemaker cells |
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Definition
1. sino-atrial (SA) node: collection of PM cells in right atrium. Initiate heart beat (automatic), Primary- sets rate
2. Atrio-ventricular (AV) node: located between atria and ventricles |
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Term
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Definition
| spontanesous depolarizations of membrane to threshold. results from spontaneous opening of ion channels |
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Term
| Chemical and Neural Signaling of PaceMaker cells |
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Definition
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Term
| How are depolarizations of pacemaker cells transmitted to contractile? |
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Definition
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Term
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Definition
Wave of contraction through cardiac muscle, as contractile cells are depolarized to threshold they contract.
Atria contracts as a unit and the ventricles contract as a unit |
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Term
Order of Spread of Excitation between cells:
Coordination due to: |
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Definition
atria contracts first followed by ventricles.
Presence of Gap junctions and conduction pathways. |
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Term
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Definition
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Term
| Major pathways of conducting cells |
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Definition
-internodal pathways: between SA and AV nodes
-Bundle of His (ventricles)
-Purkinje fibers (ventricles) |
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Term
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Definition
Interatrial Path
SA node-R. atrium-L.atrium
Rapid
Simultaneous contraction of R&L atria
--Internodal Path
SA node-AV node
--AV node Transmission
only path from atria to ventricals
slow conduction
atria contracts before ventricles |
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Term
| Spread of Excitation into Ventricles |
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Definition
down bundle of his
up purkinje fibers |
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Term
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Definition
external measure of electrical activity of the heart
non invasive
used for clinical abnormalities in conduction of electrical activity in heart |
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Term
| Is the body a good conductor of electricity? |
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Definition
| Yes, currents in body can spread to surface |
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Term
| How is electrical activity measured? |
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Definition
electrodes (leads) placed on skin, arranged so one positive and one negative. When eletrical current travels toward the + there is upward deflection and when travelling away there is a down deflection.
The view waves of depolarization that pass through muscle. Leads are positioned so center is the heart |
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Term
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Definition
P- atrial depolarization
QRS- ventricle depolarization
T- ventricle repolarization |
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Term
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Definition
Sinus rhythm- generated by SA node
Tachycardia- fast
Bradycardia-slow |
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Term
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Definition
Loss of coordination of electrcal activity
-Atrial fibrillation=weakness
Ventricular fib=death within minutes |
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