Exam 4 Lecture 1 Flashcards by Nic Stroud

Lower part of the heart, per lecture

Ventricles

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What is Phase 2 of Cardiac AP

Plateau Phase: Ca++ influx via L-Type Ca++ channels; K+ channels still closed/closing [decreased permeability]

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What is the Subendocardium
*What could happen here and why

Super deep muscle layers where a MI would probably happen [increased wall/chamber pressures]

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What is the Epicardium
*What sit on these and go deeper into the heart

Outside wall of the heart; most superficial
*Vessels sit here and go deeper into the heart

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How do Myocytes communicate with each other?

Gap Junctions

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How many nuclei/nucleus do each myocyte have?

1 nucleus

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What is the Parietal Pericardium

Inner, stretchy layer

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Ionic Current is dependent on? 2 things

CG/ electrochemical gradient and Amount of Ion channels

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How long is a Cardiac AP

around 200 ms

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What is the Myocardium

Bulk of Muscle Wall

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What are the Parts of the Pericardium

Epicardium, Pericardial Space, Parietal, Fibrous

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What is the Pericardium

The connective tissue sac that covers the heart

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Are ACE and ARBS safe in pregnant women?

No, mess w RAAS system and are teratogenic

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What are Cardiac Stem cells?
*Fast or slow process

Patching areas of dying cells; slow process

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What are cardiac fibroblasts?
*When are they activated?
*What disease process is a result of increase fibroblasts?
*Tx for this disease process

Lay down scar tissue
*Activated when stem cells are overwhelmed; can also lay down unnecessary scar tissue
*CHF from increased scar tissue = decreased conductance
*Tx: ACE and ARBS [Teratogenic]

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What is a way to cause a AV HB in a pt?
*What type of surgery
*What CN are involved
*Pathophys of this

Eye muscle reflex due to eye surgery
*V [trigeminal] + X [vagus]
*Sensory perception in eye socket, sends input to brain, vagus nerve then signals massive vagal output, which prevents AP in AV node [wait 30 sec to get HR back]

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Purkinje Fibers
*VRM
*Threshold Potential
*What does it rely on to fire an AP

-90 mV; Threshold is -70 mV
*Can SLOWLY fire own AP, but mostly relies on upstream AP to help fire AP

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What is Phase 3 of Cardiac AP

Increased K+ channel permeability, leading to down slope before Phase 4 [VRM]

What are Intercalated Discs
*where are they only located
*What are located here

High surface area connection points of the cardiac cell to other cardiac cells
*only in heart
*Gap junctions

There is less Ca++ coming in than Na+ in an AP, why?

Less Ca++ channels than Na+ channels

How many cardiac AP phases do we have?

5 total

What is Phase 0 of Cardiac AP

Na+ rapid upstroke in a fast manner; K+ channels begin closing right at top of Phase 0, before Phase 1

What is Phase 1 of Cardiac AP

Fast Ca++ influx via T-Type Ca++ Channel; K+ channels begin to close [decreased permeability]

In a relaxed state, how does the heart look?
*What about the H-band
*Under or overstretched? Why?

not relaxed at optimum degree
*No H-Band
*Understretched to produce more force: Increased EF

What is Phase 4 of Cardiac AP *How to start AP

VRM @ around -90 w/ slight slope *can slowly fire AP by itself over time, but mostly gets AP from Na+ influx via gap junctions in upstream AP

Cardiac Muscle Tissue

Lots of myofibrils to produce more force

Cardiac Conduction Tissue

Barely any myofibrils to produce more amount and efficient AP's

Ventricle Muscle *VRM *Threshold Potential

-80 mV; Threshold is -70 mV

What does increase scar tissue cause?

No AP and no contraction

At rest, how does the Cardiac AP VRM look? *Why

Slight slope due to increased Na+ permeability

Superficial to Deep, Layers of the Heart

Fibrous Pericardium - Parietal Pericardium - Pericardial Space - Epicardium - Myocardium - Endocardium

What are Cardiac Syncytial Connections? *How many layers of the heart and how do they operate *Name of the layers, per slide *Efficiency and how are they connected

The Arrangement of heart muscle *2 Layers: Endocardial and Epicardial Fibers twist/rotate in opposite directions, leading to better force [think wring out a wet towel] *Highly efficient and connected via electricity

What is the threshold potential for Purkinje/ Ventricle

-70 mV

What is the Pericardial Space

Filled with mucus and fluid to help the heart move; painful if you have pericardial rub

What is the Endocardium

Deep Cardiac Muscle

What is the conduction system of the ventricle *What is their role

Purkinje Fibers *Conduct/Relay AP

Deep to Superficial, Layers of the Heart

Endocardium - Myocardium - Epicardium - Pericardial Space - Parietal Pericardium - Fibrous Pericardium

In Purkinje Fibers, if AV heart block, how is PF effected? *Think Lag time *How long is lag time

AV heart block blocks conductance signal, so increased lag time of about 30 sec for the PF to fire an AP

What is the thickest cardiac tissue?

Myocardium

What is the Fibrous Pericardium *What is it similar to

Outside, stiff, leathery layer *Similar to Dura layer; difficult to expand

Upper part of the heart, per lecture

Atrium

What is Ohm's Law *What does each thing stand for *what does i mean?

V = IR V = voltage I = Current R = Resistance i- Ionic current

2 Things that cause Cardiac Ischemia

Increased wall pressure and clogged vessels