EX1; Cardiac Muscle Flashcards Preview

AU14 Physiology > EX1; Cardiac Muscle > Flashcards

Flashcards in EX1; Cardiac Muscle Deck (27):
1

What is the one main feature of cardiac muscle that distinguishes it from skeletal muscle

the filaments in cardiac sarcomeres are not all the same length; possibly related to the need of the heart to pump blood following different amounts of dissension during filling

2

What two contractile proteins are found in both skeletal and cardiac muscle

one of the myosin heavy chains (beta)
the troponin C in slow (but not fast skeletal muscle)

3

This contractile protein is expressed in cardiac muscle but not so much skeletal muscle (except masseter)

cardiac myosin heavy chain (alpha)

4

A unique isoform of this is expressed in cardiac muscle

troponin I

5

True or False
Nebulin is present in cardiac sarcomeres

False; it is not

6

This organelle is much larger in cardiac muscle than in skeletal muscle

mitochondria

7

Cardiac muscle cells are much smaller or larger than skeletal muscle cells

smaller

8

How are cardiac cells attached to one another compared to skeletal muscle cells

cardiac cells are attached end-on-end to each other via the physical connection of an *intercalated disk*
skeletal cells are attached to endows

9

Small regions along each intercalated disk that are further specialized for the rapid and direct transmission of action potentials between adjacent cells are what

gap junctions

10

Gap junctions allow for the heart to function as one unit, how?

They allow the quick passage of action potentials throughout all the ventricular cells simultaneously

11

The electrical synapses of the heart does not involve this

chemical transmitters for AP transmission

12

Where else would you find gap junctions besides the heart

in the brain tissues
not present in skeletal muscles

13

True or False
The events in the heart are much slower

True; the AP in ventricular cells ~200ms, AP in skeletal muscles ~3ms

14

The AP in cardiac muscle lasts until when, whereas in skeletal muscle the AP is complete before muscle even begins to shorten

twitch tension is relaxed

15

Why does the heart have such a long absolute refractory period during the cardiac AP

it prevents the heart from undergoing a tetanic contraction which could, otherwise, be life threatening

16

What is the first phase conductance changes (after depolarization) during ventricular action potential

Kꜛ
Naꜜ
(less NA coming into cell)

17

What is the second phase conductance change during ventricular AP

Caꜛ
Kꜜ

18

The "decrease" of K conductance in phase 2 allows for what to occur

it keeps the voltage gated Ca channel open

19

What is the third phase conductance change during ventricular AP

Kꜛ
Caꜜ
decrease in Ca, major increase in K

20

What is the fourth phase conductance change during ventricular AP

essentially no net flow

21

What is the major source of activating Ca ions in the heart

they enter cells from interstitial space by passing through channels in sarcolemma during plateau phase of AP

22

The activating Ca from the interstitial space somehow trigger what

the release of other Ca ions from the sarcoplasmic reticulum which binds to troponin C and causes activation of cardiac muscle

23

What is the name of the process in which interstitial space Ca ions induce the SR to release Ca

calcium induced calcium release

24

The primary mechanism for the removal of Ca ions from the sarcoplasm utilizes what

a Ca ATPase pump
another pump like this moves ions *out of the cell* across the sarcolemma

25

This mechanism in the sarcolemma moves Na in and Ca out of the cell, does not use ATP, it is driven by a Na gradient

Na/Ca exchanger

26

There is a secondary action transport involving the Na/Ca exchanger which maintains what

It consumes ATP to maintain difference in Na concentrations

27

Which source an removal system of Ca involves massive quantities

Source; Ca ions from SR
Removal; Uptake by SR (it isn't really shuttled out, it just is moved around)