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

Lecture 10/14: Cardiac Flashcards

Test 4 (52 cards)

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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

Study These Flashcards
A

Thick

Deepest

22
Q

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

23
Q

What does the pericardium consist of? Describe them

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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

Study These Flashcards
A

F

Fibrous pericardium is stiff and difficult to expand

25
What helps reduce friction in the pericardium?
Fluid/mucus in the pericardial space
26
You think you're having a heart attack... What could this be?
Friction in the pericardium d/t inflammation or loss of fluid/mucus in pericardial space
27
Where is the subendocardium?
Deep Endocardium or deep myocardium
28
Where do infarcts/MIs normally happen? Why?
Subendocardium in L ventricle Ventricular wall pressures are highest here
29
Cardiac sacromeres are naturally _________ the actin & myosin _________
under stretched slightly overlap **Myosin touches Z-disc**
30
What is the Vrm of the purkinje fibers?
-90 mV
31
What is the threshold potential of the purkinje fibers?
-70 mV
32
What is the Vrm of the ventricular muscles?
-80 mV
33
What is the conduction system within the ventricles?
Purkinje fibers
34
T/F: Purkinje fibers contract
F
35
T/F: Purkinje fibers are last to fire an AP
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
Whats the difference between Ventricles and purkinje fibers?
Ventricles: permits AP and contracts in response Purkinje: permits AP only
37
How long does it take for purkinje fibers to fire 1st AP after escaping from complete heart block?
30 seconds **Subsequent ones dont take this long**
38
What is a lag?
Time is takes to get from Vrm to threshold potential
39
Why is there a slope at phase 4 in the ventricles?
Increasing permeability to Na+ at rest
40
Describe how eye procedures cause heart blocks
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
What should we be cautious of in eye procedures?
People with heart problems 5 & dime reflex Need to take extra precatious
42
What is a ventricular muscle cell?
Ventricular myocyte
43
Ventricular AP: Describe phase 4
**Resting** Small slope d/t increasing Na+ permeability
44
Ventricular AP: When are K+ channels closing?
Phase 0-2
45
Ventricular AP: Describe phase 0
**Rapid upstroke** Fast Na+ channels open/close
46
Ventricular AP: Describe phase 1
Fast T-type Ca++ channels open
47
Ventricular AP: Describe phase 2
**Plateau phase** Slow L-type Ca++ channels open (takes over from T-type Ca++)
48
Ventricular AP: Describe phase 3
K+ channels open
49
Ventricular AP: Where is the Na+ coming from?
Cells immediately up/down stream via gap junctions
50
Ventricular AP: How long is the AP? Why?
200 milliseconds allows for coordinated contractions betweens syncytiums
51
What is Holmes law?
Voltage (V) = Current (I) x Resistance (R)
52
Ventricular AP: Where are K+ channels open?
Phase 3-4

A/P (33 decks)

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