L10: Introduction to the physiology of CVS

Question 1

what is the difference between mild or chronic heart failure and severe heart failure ?

Answer 1

in mild heart failure the heart is still Abel to supply the vital organs , particularly the brain . something it cannot do when faced with severe heart failure .

Question 2

what chamber of the heart works as a volume pump?

Answer 2

atria

Question 3

what are the 2 trio-venticular values ? what are the 2 semilunar valves?

Answer 3

tricuspid and mitral valves

pulmonary and aortic

Question 4

what causes heart valves to open and close ?

Answer 4

difference in pressure gradient

Question 5

what are the functions of the AV fibrous tissue ring ?

Answer 5

acts as a cardiac skeleton : by serving as origin and insertion to the cardiac muscle fibers

electrical insulator :separating the arterial sheet of muscles from ventricular sheet of muscle . it is pierced by the atriventicular bundle (( AV bundle ) which is the only connection between atria and ventricles

Question 6

what is the function of papillary muscles and chords tendinea ?

Answer 6

it prevents the opening of valves in the opposite direction

Question 7

what are the functions of desmosomes and gap junctions in the intercalated discs of cardiac muscle ?

Answer 7

desmosomes are responsible for cell-cell cohesion and mechanical unity while gap junctions are responsible for electrical syncytium

Question 8

what are junctional “ conductive “ tissue ?

Answer 8

(His bundle , bundle branches and purkinje fibers ) a specialized system of conduction of the excitation wave to the rest of the heart as quickly as possible

Question 9

what nodal tissue has the highest firing rate ?

Answer 9

SA node , at 90-100 BPM

av node has a firing rate of 40-50

Question 10

what other tissue can be responsible for auto-rhythmicity of the heart ?(other than SA and AV nodes )

Answer 10

His- purkinje system ( dormant pace makers ) have a much lower rate at 20-25 BPM

Question 11

What has the slowest conduction ?

Answer 11

AVN

Question 12

what is the significance of AVN delay ?

Answer 12

allows the atria to contact and empty their blood content into ventricle before ventricular contraction occurs

Question 13

what is the significance of AVN block ?

Answer 13

protects ventricles against high ectopic atrial rhythm

Question 14

what part of the heart has the highest conduction velocity ?

Answer 14

purkinje fiber endings of his bundle ( conducting pathway )

Question 15

what is the significance of the very high conduction velocity of purkinje fibers ?

Answer 15

to ensure synchronous activation of both ventricles

Question 16

what is the rapid conduction pathway ?

Answer 16

anterior and middle and posterior internal tracts ( conduct impulse through arterial muscle from SA and AV node )

intertribal tract ( conduct impulse from SAN to left atrium )

Question 17

what parts of the heart have slow excitability and what parts have fast response ?

Answer 17

SAN and AVN have a slow response while purkinje fibers , atrial , ventricular muscles have a faster response