Exam 4 Lecture 1 Flashcards
Lower part of the heart, per lecture
Ventricles
What is Phase 2 of Cardiac AP
Plateau Phase: Ca++ influx via L-Type Ca++ channels; K+ channels still closed/closing [decreased permeability]
What is the Subendocardium
*What could happen here and why
Super deep muscle layers where a MI would probably happen [increased wall/chamber pressures]
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
How do Myocytes communicate with each other?
Gap Junctions
How many nuclei/nucleus do each myocyte have?
1 nucleus
What is the Parietal Pericardium
Inner, stretchy layer
Ionic Current is dependent on? 2 things
CG/ electrochemical gradient and Amount of Ion channels
How long is a Cardiac AP
around 200 ms
What is the Myocardium
Bulk of Muscle Wall
What are the Parts of the Pericardium
Epicardium, Pericardial Space, Parietal, Fibrous
What is the Pericardium
The connective tissue sac that covers the heart
Are ACE and ARBS safe in pregnant women?
No, mess w RAAS system and are teratogenic
What are Cardiac Stem cells?
*Fast or slow process
Patching areas of dying cells; slow process
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]
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]
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
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
