term 4 week 1 Flashcards
(33 cards)
Overview of the Cardiovascular System
* 3 components
- The Heart
- Blood Vessels
- Blood
components of heart
- Atria
- Ventricles
- Interatrial Septum
- Interventricular Septum
- Atrioventricular valves
- Semilunar valves
- Blood Vessels
- Arteries
- Arterioles
- Capillaries
- Venules
- Veins
- Blood
- Erythrocytes
- Leukocytes
- Platelets
- Plasma
Pulmonary Circuit
- Blood flow between the lungs
and heart - Supplied by the right side of the
heart
Systemic Circuit
- Blood flow between the rest of
the body and heart - Supplied by the left side of the
heart
- Right atrium
- Receives deoxygenated blood from the body
- Blood passes through the Right AV, _________,valve
- Enters the R ventricle
- Right ventricle
- Pumps blood into the pulmonary circuit
- Blood passes through the pulmonary semilunar valve
- Pulmonary Trunk → Pulmonary arteries → Lungs
tricuspid
- Left atrium
- Receives oxygenated blood from the lungs
- Blood passes through the Left AV,__________, valve
- Enters the L ventricle
- Left ventricle
- Pumps blood into the systemic circuit
- Blood passes through the aortic semilunar valve
- Aorta → Arteries → Arterioles → Capillaries → Venules → Veins
bicuspid
Conduction pathways
Depolarization spreads throughout the heart very rapidly facilitating a coordinated contraction pattern
Intercalated disks
- Form junctions between adjacent cardiac muscle fibers
- Contain a high concentration of gap junctions for rapid transmission of the action potential
Action Potentials are initiated at the _______ Node
Sinoatrial (SA)
Small cluster of cells in the right atrial wall, just inferior to the entrance of the superior vena cava
* Fastest spontaneous depolarization rate:
* Approximately 60 - 80 bpm
* Natural pacemaker of the heart
* Called sinus rhythm
Sinoatrial (SA)
- Action potential travels from the SA Node toward the ________
- Travel along internodal pathways
System of conduction fibers that run along the walls of the atria to the AV Node - Travel along Bachman’s bundle
System of conduction fibers that run along the walls of the Right atria to the Left atria
AV Node
impulse moves along internodal pathways and travel along bacmans bundle….
* The impulse is conducted to the cells of the AV node
* Atrioventricular (AV) node
Located in the interatrial septum just above the tricuspid valve
Can spontaneously depolarize
* Overdrive suppression
SA node firing at a greater frequency suppresses the _______ of the AV node
automaticity
After a slight delay the impulse travels from the AV Node through the Bundle of His
What is the bundle of his ?
where is it located?
compact bundle of muscle fibers
located in the interventricular septum
what is located in the interventricular septum ?
bundle of HIS
After a slight delay the impulse travels from the AV Node through the Bundle of His
Action potential passes rapidly through the Bundle of
His to the R and L ______
bundle branches
what are the R and L bundle branches and where are they located ?
Right and Left Bundle Branches
* Located in the interventricular septum
* Conduct the impulse to the right and left ventricles
* They pass the depolarization impulse rapidly to the
Purkinje fibers
The impulse travels from the Bundles Branches to the Purkinje Fibers
What are purkinje fibers?
Purkinje Fibers
* Large diameter, rapid conduction fibers
* Spread the impulse to the ventricular myocardium
Responsible for approximately simultaneous excitation of the ventricles which is essential for
efficient pumping
Total time elapsed between excitation of SA node and
ventricular depolarization is about
.22 seconds
Phases of the Cardiac Action Potential
- Phase 4: Resting membrane potential
- K + continually leaks out of the cell
- Keeps the cell at -90 mV
- Phase 0: Depolarization
- Causes “Fast” Na + voltage-gated channels to open
- Increases permeability to Na +
- Na + ions follow their electrochemical gradient into the cell
- Membrane potential becomes more positive
- Phase 1: Repolarization
- Na + voltage-gated channels close
- Decreases permeability to Na+
- K+ voltage-gated channels open
- Increases the flow of K + out of the cell
- Ca2+ voltage-gated channels open
- Increases permeability to Ca2+
- Ca2+ flows into the cell
- Phase 2: Plateau
- K+ continues to move out of the cell
- Ca 2+ channels stay open
- Ca2+ influx prolongs depolarization
- Membrane remains depolarized
- The purpose of the plateau phase is to prevent tetany (prolonged contractions) that would interfere with the pumping ability of the heart
- Phase 3: Repolarization
- Ca 2+ channels begin to close
- Ca2+ is pumped back into the SR
- Ca2+ is pumped out of cell into the extracellular fluid
- K+ voltage-gated channels remain open
- K + continues to flow out of cell
- Results in repolarization
- Phase 4: Resting membrane potential
- Re-established at -90 mV
- K+ voltage gated channels close
- Action potential spreads along the cell membrane and down T-tubules
- Causes _____ voltage-gated channels to open
CA 2+
- SR Ca 2+ voltage-gated channels release Ca2+ into the extracellular fluid
- Membrane Ca 2+ voltage-gated channels allow Ca2+ from extracellular fluid to enter
cell
- Cardiac muscle has less extensive SRs compared to skeletal muscle
- Therefore, cardiac muscle contraction depends heavily on _______
Ca2+ influx from the
extracellular fluid
- When depolarization occurs, Ca 2+ voltage-gated channels open
- Allows influx of Ca 2+ from the extracellular fluid
- The strength of cardiac muscle contraction is directly related to the amount of Ca2+ that enters the cell from the extracellular fluid
The strength of cardiac muscle contraction is directly related to the amount of ___ that enters the cell from the extracellular fluid
Ca 2+
