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A/P > Lecture 10/14: Cardiac > Flashcards

Lecture 10/14: Cardiac Flashcards

Test 4

1
Q

What type of muscle is cardiac muscle?

A

Visceral/unitary smooth muscle

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2
Q

Cardiac muscle contracts as a _______

A

unit

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3
Q

Describe the borders of cardiac cells

A

They are called intercalated discs

The are convoluted to increase surface area to allow for more gap junctions

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4
Q

Where are intercalated discs?

A

ONLY IN THE HEART

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5
Q

How many nuclei do cardiac cells have?

A

1

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6
Q

What does the striation pattern represent?

A

actin & myosin

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7
Q

Cardiac & ______ sarcomeres are similar

A

skeletal

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8
Q

What is the role of stem cells in cardiac muscle?

A

SLOWLY fix other cells that die off

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9
Q

_______ cells lay down scar tissue

A

Fibroblasts

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10
Q

What happens if stem cells get overwhelmed?

A

Fibroblasts will lay down scar tissue

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11
Q

What is a condition where fibroblasts unneccessarily lay down scar tissue? How does this affect the heart? What medication can we give to combat this?

A

CHF

Scar tissue doesn’t contract normally and it disrupts the electrical transduction system of the heart

ACE inhibitors (-prils)

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12
Q

What is an important growth factor in our body?

A

Angiotensin 2

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13
Q

Why do you NOT want to take ACE inhibitors or ARBs while pregnant?

A

They block RAA system and angiotensin 2 is an important growth hormone factor. Blocking angiotensin 2 would prevent the proper development of the fetus.

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14
Q

ACE inhibitors has what effect on after load?

A

reduces after load

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15
Q

Describe the different types of Syncytial connections

A

“Syncytiums”

  1. Referring to 2 ventricular layers (endocardium & epicardium) oriented in 2 different directions.
    -This allows for a twisting mechanism to get blood out of the ventricles (like twisting water out a towel)
  2. Top/Bottom of heart referring to atria = top & ventricles = bottom
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16
Q

What is the vast majority of cardiac cells?

A

Muscle tissue

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17
Q

Why is the heart able to produce so much force?

A

The vast majority of the heart is a muscle tissues. It’s has lots of myofibrils in muscle cells to produce force from action potentials.

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18
Q

Describe Conduction tissue

A

Transmits AP faster than muscle tissue bc it doesn’t have myofibrils (slows down AP)

Doesn’t produce much force

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19
Q

What are the layers of cardiac muscle from deep to superficial?

A

Endocardium
Myocardium
Epicardium
Pericardial space
Parietal pericardium
Fibrous pericardium

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20
Q

What are the layers of cardiac muscle from superficial to deep?

A

Fibrous pericardium
Parietal pericardium
Pericardial space
Epicardium
Myocardium
Endocardium

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21
Q

The ______ endocardium layer is the ________ cardiac muscle

A

Thick

Deepest

22
Q

What layer makes up the bulk of the cardiac muscle wall?

A

Myocardium

23
Q

What does the pericardium consist of? Describe them

A

connective tissues that from a sac and enclose the heart

  1. Pericadial space: fluid/muscous filled area; reduces friction with beating and moving of heart
    -Superior to the epicardium
  2. parietal pericardium: inner area; closest to pericardial space; easily expands
  3. fibrous pericardium: outer area; stiff & difficult to expand.
24
Q

T/F: Alot of extra fluid can fit in the pericardial space

A

F

Fibrous pericardium is stiff and difficult to expand

25
Q

What helps reduce friction in the pericardium?

A

Fluid/mucus in the pericardial space

26
Q

You think you’re having a heart attack… What could this be?

A

Friction in the pericardium d/t inflammation or loss of fluid/mucus in pericardial space

27
Q

Where is the subendocardium?

A

Deep Endocardium or deep myocardium

28
Q

Where do infarcts/MIs normally happen? Why?

A

Subendocardium in L ventricle

Ventricular wall pressures are highest here

29
Q

Cardiac sacromeres are naturally _________ the actin & myosin _________

A

under stretched

slightly overlap

Myosin touches Z-disc

30
Q

What is the Vrm of the purkinje fibers?

A

-90 mV

31
Q

What is the threshold potential of the purkinje fibers?

A

-70 mV

32
Q

What is the Vrm of the ventricular muscles?

A

-80 mV

33
Q

What is the conduction system within the ventricles?

A

Purkinje fibers

34
Q

T/F: Purkinje fibers contract

A

F

35
Q

T/F: Purkinje fibers are last to fire an AP

A

T

Rate of conduction is very slow; before they are depolarized, another area in the heart (SA/AV node) has already fired another AP

36
Q

Whats the difference between Ventricles and purkinje fibers?

A

Ventricles: permits AP and contracts in response

Purkinje: permits AP only

37
Q

How long does it take for purkinje fibers to fire 1st AP after escaping from complete heart block?

A

30 seconds

Subsequent ones dont take this long

38
Q

What is a lag?

A

Time is takes to get from Vrm to threshold potential

39
Q

Why is there a slope at phase 4 in the ventricles?

A

Increasing permeability to Na+ at rest

40
Q

Describe how eye procedures cause heart blocks

A

Pressure sensors in the eye trigger reflexes from manipulation –> V & X reflex = 5 & dime reflex

pressure into is sent to CNS from cranial nerve-V (trigeminal nerve on the side of the face) which is then sent to cranial nerve-X (vagus).

This causes massive vagal output from CNS

HR may go to 0 but Purkinje fibers should kick in at about 30 seconds

41
Q

What should we be cautious of in eye procedures?

A

People with heart problems

5 & dime reflex

Need to take extra precatious

42
Q

What is a ventricular muscle cell?

A

Ventricular myocyte

43
Q

Ventricular AP: Describe phase 4

A

Resting
Small slope d/t increasing Na+ permeability

44
Q

Ventricular AP: When are K+ channels closing?

A

Phase 0-2

45
Q

Ventricular AP: Describe phase 0

A

Rapid upstroke
Fast Na+ channels open/close

46
Q

Ventricular AP: Describe phase 1

A

Fast T-type Ca++ channels open

47
Q

Ventricular AP: Describe phase 2

A

Plateau phase
Slow L-type Ca++ channels open (takes over from T-type Ca++)

48
Q

Ventricular AP: Describe phase 3

A

K+ channels open

49
Q

Ventricular AP: Where is the Na+ coming from?

A

Cells immediately up/down stream via gap junctions

50
Q

Ventricular AP: How long is the AP? Why?

A

200 milliseconds

allows for coordinated contractions betweens syncytiums

51
Q

What is Holmes law?

A

Voltage (V) = Current (I) x Resistance (R)

52
Q

Ventricular AP: Where are K+ channels open?

A

Phase 3-4

A/P (24 decks)

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