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Bms108 Exam Questions And 100% Correct Answers
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Bms108 Exam Questions And100% Correct Answers
1. Describe the path of blood as it passed through both the pulmonary and systemic
circuits. Begin and end at the right atrium. Include in your discussion the chambers of
the heart, heart valves and O2/CO2 status of the blood. - Answer ...
2. Describe the exchange of O2 and CO2 between the pulmonary and systemic circuits. -
Answer •Right ventricle pumps blood that is low in O2 and high in CO2 to the lung. low
pressure system
Systemic Circuit
•Left ventricle pumps blood that is high O2 and low in CO2 to all tissues
•High pressure system
3. Name the 4 heart valves and state which chambers and arteries are separated by
these valves. - Answer •Atrioventricular Valves (AV)
-Rt Tricuspid
-Lt Mitral
•Semilunar Valves
-Rt Pulmonic
-Lt Aortic
4. What causes heart valves to open or close? - Answer Open and close due to pressure
differences on either side of the valve When pressure is greater behind the valve, the
leaflets are blown open and the blood flows through the valve. However, when pressure
is greater in front of the valve, the leaflets snap shut and blood flow is stopped
5. What causes heart sounds? - Answer •Due to valve closure
•1st sound, S1, AV valves close at the start of systole
•2nd sound, S2, semilunar valves close at the start of diastole
6. Which valves close at the start of systole? Diastole? - Answer semilunar valves close
at the start of diastole. Av valves close at the start of systole
7. What are heart murmurs? - Answer 1.Insufficient Valve
,-won't fully close (leaky)
2.Stenotic Valve
-won't fully open (narrowed)
3.Hole in the Septum
8. What's the difference between an insufficient valve and a stenotic valve? - Answer
1.Insufficient Valve
-won't fully close (leaky)
2.Stenotic Valve
-won't fully open (narrowed)
9. What is the relationship between streptococcus infection, rheumatic fever and heart
murmurs? - Answer -Autoimmune disease
-Immune system attacks heart valves
-Triggered by streptococcus infection
-causes inflammation and subsequent scarring of the valves, leading to valve stenosis
or insufficiency.
10. What is the function of the intercalated discs that connect one myocardial cell to
another? - Answer Cardiac Muscle = Myocardial Cells
•Striated
•Branched
•Connected to one another by Intercalated Discs
-Desmosomes bind cells together
-Gap Junctions have connexons (channels) that act as electrical synapses
•Form Functional units
-Atrial myocardium
-Ventricular Myocardium
11. What structure in the heart separates the ventricular myocardium from the atrial
myocardium? - Answer by the non-conducting fibrous skeleton,
12. What characteristic of the ventricular myocardium allows it to act as a functional
unit of contraction? - Answer Desmosomes bind cells together
,Gap Junctions have connexons (channels) that act as electrical synapses: functional
unit of contraction
a. Atrial pressure exceeds ventricular pressure. - Answer Diastole
b. The semilunar valves have just opened. - Answer Systole
c. The AV valves have just opened - Answer Diastole
d. Blood is flowing from the right atrium to the right ventricle. - Answer Diastole
e. Blood is flowing from the left ventricle into the aorta. - Answer systole
f. The first heart sound (S1) is heard. - Answer •1st sound, S1, AV valves close at the
start of systole
g. The second heart sound (S2) is heard. - Answer •2nd sound, S2, semilunar valves
close at the start of diastole
h. The atria are contracting - Answer Diastole
i. The ventricles are contracting - Answer Systole
14. List the events of the cardiac cycle. Begin with systole and end with diastole. Include
in your answer the contraction state of the chambers, the pressure changes in the
chambers and arteries, the opening and closing of valves and the flow of blood. The
answer must be chronological and demonstrate cause and effect. - Answer 1.Ventricles
contract.
2.Ventricular pressure exceeds atrial pressure causing AV valves to close
3.Isovolumetric contraction phase; all valves are closed, contraction without blood flow.
4.Ventricular pressure exceeds aorta and pulmonary artery pressure causing semilunar
valves to open
5.Blood is ejected into the aorta and pulmonary arteries
1.Ventricles Relax
2.Aorta and Pulmonary artery pressure exceeds ventricular pressure causing semilunar
valves to close.
3.Isovolumetric Relaxation Phase, all valves are closed, relaxation without blood flow
4.Atrial pressure exceeds ventricular pressure causing AV valves to open.
5.Blood fills the ventricles to 80% of End Diastolic Volume.
6.Atria contract and fill ventricles to 100% of End Diastolic Volume.
15. What does it mean that the heart is autorhythmic? - Answer •The heart is
, Autorhythmic because it initiates its own action potentials
16. Explain the function of the conduction system and list its component parts. - Answer
•A specialized group of cells that initiate and propagate the action potentials in the
heart.
•Components of the conduction system are:
-Sinoatrial (SA) node
-Atrioventricular node
-Bundle of His
-Purkinje Fibers
•Sinoatrial (SA) Node is the pacemaker of the heart
17. What part of the conduction system is the pacemaker of the heart and why? - Answer
•Sinoatrial (SA) Node is the pacemaker of the heart
18. Describe the initiation and spread of the action potential through the conduction
system and the atrial and ventricular myocardia. - Answer Myocardial Action Potential
The contractile myocardial cells of the heart have a resting membrane potential of about
-80 mV. Action potentials that originate in the SA node bring the myocardial cells to
threshold and stimulate action potentials. Voltage-gated Na+ channels open. Na+
diffuses into the cell down its electrochemical gradient, depolarizing the cell to -20 mV.
Na+ channels close. Now the action potential has a plateau phase. During the plateau
phase, voltage-gated K+ channels and voltage-gated Ca2+ channels open
simultaneously. K+ diffuses out of the cell while Ca2+ diffuses into the cell, maintaining
the action potential in a state of depolarization for an extended period of time (200
msec). Next the Ca2+ channels close, more K+ channels open, and rapid K+ efflux out of
the cell repolarizes the cell to resting membrane potential.
19. What characteristic of conduction system cells makes them autorhythmic? - Answer
The rhythmic beating of the heart is controlled by a small group of cells in the wall of the
right atrium, collectively called the sinoatrial node (typically referred to as the SA
node).The autorhythmic cells of the SA node continuously intiate action potentials
because they do not have a resting membrane potential.Rather their membrane
potential is always drifting towards threshold.
20. Explain how the pacemaker potential stimulates an action potential in an SA node
cell. - Answer 1.Hyperpolarization stimulates opening of HCN channels.
2.Na+ influx causes depolarization to threshold. This is the pacemaker potential (shown
in red).
3.Pacemaker potential stimulates an action potential. Ca2+ influx followed by K+ efflux.
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