Functional Structure Of Heart Flashcards

1
Q

Mention importance of inelastic nature of percardium

A

Prevent sudden heart dilatation, but it allows for physiological variation in cardiac size.

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2
Q

Pericardium can adapt to slow stretch during ….

A

Growth or cariac hypertrophy

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3
Q

Functions of A-V ring

A
  1. Cardiac skeleton for origin & insertion for cardiac muscles with atrial above & ventricular below.
  2. Electric insulator between atria & ventricles. It is pierced by A-V bundle.
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4
Q

Describe the left venticular aid, is the opposite true?

A

When there is failure of right ventricle, healthy left ventricle can give an aid to RV, where its contraction will pull upon the free trangular RV wall & compress blood within its chamber against thick IV septum, thus raising pressure inside RV.
There is no RV aid.

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5
Q

Mention important of junction of cardiac muscle fibers

A

Gap junctions

Desmosomes

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6
Q

Mention important proteins in skeletal msucles

A

Myosin, actin, tropomyosin & troponin

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7
Q

T tubeles contain …., which are …..

A

Dihydropyridine receptors

Voltage-gated Ca++ channels

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8
Q

Terminal cisternae has …., which is ….

A

Ryandodine receptors

Ca++ release channels

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9
Q

Function of T-tubule

A

Rapid spread of excitation wave from surface membrane deep into interior of the muscle fiber.

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10
Q

Describe Ca++ indiced Ca++ release

A

When DHP receptors are activated, the Ca++ entered though it from the ECF triggers the release of Ca++ from cisterns of SR via ryanodine receptors.

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11
Q

What is meant by: the heart is a functional syncytium?

A

Acts as a single unit & doesn’t have multiple units unlike skeletal muscle motor units, thus to a thershold stimulus it responds fully, but with subthershold there is no response. All or none rule.

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12
Q

Mention structures that allow heart to act AS IF it is a true syncytium & their functions

A

Gap junction: allow high electric conduction with low resistance (1/400 of the normal) (electric syncytium)
Desmosomes: strong mechanical attachments between adjacent cell membranes. (Mechanical syncytium)

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13
Q

Mention cardiac characteristics which allow aerobic metabolism dominance.

A

Abundant blood supply
Hight content of myoglobin
Numerous and large elongated mitochondria

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14
Q

GR: Cardiac action potential is not initiated by the neural activity

A

There is specialized muscle tissue which initiates its own action potential (autorhythmic tissue cells) which then spreads by the conductive tissue cells to contractile cells.

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15
Q

Write a short note on nodal tissue

A

SAN & AVN

Specialized in initiation of the excitation wave at a regular rhythm

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16
Q

Write a short note on junctional tissue

A

His bundle, Rt & Lt bundle branches & Purkinje fibers

Specialized system for conduction of the excitation waves ti the rest of the heart as fast as possible.

17
Q

Write a short note on contractile tissue

A

Atrial muscle & ventricular muscle

Its ability to contract and act as a pump