Lecture 6 - Cardiac Muscle Tissue Flashcards Preview

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Flashcards in Lecture 6 - Cardiac Muscle Tissue Deck (25):
1

Describe differences between skeletal muscle and cardiac muscle.

Triad ofSR and T tubule (skeletal), died of SR and T-tubule (cardiac), branching cardiac cells, syncitium (cardiac)

2

Describe cardiac A.P. shape & ion conductance.

Phase 4: slow Na+ leak Phase 0: threshold reached and voltage gated Na open, causing rapid upstroke Phase 1: beginning of depolarization, but arrested by phase 2 Phase 2: voltage gated Ca2+ open, causing cardiac AP "plateau" Phase 3: K+ effluent prompting depolarization

3

Location of fast cardiac action potentials

Conductive tissues of the atria and ventricles (NOT Purkinje fibers)

4

Slow action potentials found in what tissues?

SA and AV nodes, Purkinje fibers,

5

What type of tissues have slow, automatically depolarizing cells?

Slow SA/AV nodal tissues (automaticity)

6

Fast APs are caused by _________.

Na+, K+, and Ca2+ ion conductance

7

Slow AP tissues lack _____ channels and have ____ channels, resulting in slow conduction.

Na+; Ca2+

8

Large diameter, rapidly conductive of APs, high amplitude APs

Fast contractile myocytes

9

Cardiac tissue with rapid upstroke and large diameter

Fast, non-contractile myocytes

10

Type of cardiac tissue with slow depolarization, small diameter, and low amplitude

Slow, non-contractile fibers

11

Two sources of Ca2+ in cardiac contraction:

1)Ca2+ from phase 2 (plateau) of AP diffuses through DHP-R into sarcoplasm 2) Ca2+ released from SR during AP transmission to T-tubule

12

Why is diffusion of the Ca2+ from the plateau phase of the AP so important?

Without the calcium from the T tubules, the strength of cardiac muscle contraction would be reduced considerably because the sarcoplasmic reticulum of cardiac muscle is less well developed than that of skeletal muscle and does not store enough calcium to provide full contraction.

13

Describe the similarities between skeletal & cardiac muscle.

Banded appearance due to sarcomeres, mononucleate

14

Slow action potential conducting tissues are found in ______. Why?

SA and AV nodal tissues. These act to slowly depolarize, causing the production of the cells "pacemaker" ability.

15

Fast action potentials serve to ______.

"Conduct and contract"

16

Slow action potentials serve to ______.

Set the pace

17

Slow action potential tissues (SA and AV nodal tissues) resting membrane potential:

-60 mV

18

Past action potentials RMP is:

Appx. -90 mV

19

Cardiac electromechanical coupling Ca2+ comes from?

1) Diffusion thought the DHP-R (from plateau phase) 2) Released from the SR through Ry-R

20

There is a _____ delay from the SA node to the Bundle of His

0.16 sec

21

Ion conductance at A-F

Q image thumb

A) Na in

B) K out

C) Some K out

D) Some Ca in

E) Ca close, K out

F) Na leak in

22

What channel is responsible for the less negative RMP in fast action potential cardiac fibers?

Leaky Na+ channels 

23

What is the RMP of slow action potential cardiac fibers?

- 60 mV

24

_____ ESV (or pre-load) will increase stroke volume

Increase

25

_____ ESV (after load) will increase stroke volume 

Decreasing