Inherent Properties of the Heart Flashcards by Scott Roberts

What are the 4 main properties of the heart

CERC
Rhythmicity
Excitability
Conductivity
Contractibility

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which ventricle does the most work in the heart, and why

Left Ventricle, pumps blood to most of the body

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Which ventricle pumps blood to the lung

Right Ventricle

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if there was an issue with blood supply to the lung, which chamber of the heart does this correspond with

Right Ventricle

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what do you start losing after a MI

layers of the heart, heart becomes weaker

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in histology, what are the main differences between skeletal and cardiac muscle

Skeletal/Cardiac
not branched/branched
nice straight lengths/disorganised
lack of mitochondria/mitochondria

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what are the 3 main layers of the heart

Pericardium
Myocardium
Endocardium

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what is the most outer protective layer of the heart

Pericardium

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what is the role of the pericardium

Prevents cardiac Distention and excessive movement
Lubricant

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what is the middle layer of the heart

Myocardium

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what is the role of the myocardium

synchronised contraction and relaxation of the heart

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What is the innermost layer of the heart

Endocardium

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what is the role of the endocardium

lines the heart
reduces friction of blood flow in chambers
conduction system

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what is the layer in the heart the lining covering the trabeculae

Endocardium

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what type of connective tissue lies between the pericardium and the myocardium

subendothelial layer - thin collagen fibres
Sub-cardiac layer - thick collagen fibres

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which layer is the muscle layer

myocardium

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STRUCTURES WITHIN A CARDIOMYOCYTE
The T tubules are always found at the ___ disks

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describe an intercalated disc

form the staircase pattern, they act as anchoring points for the muscle fibres (filaments)

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layers of the heart from superficial to deep

Fibrous Pericardium
Serous Pericardium (parietal layer)
Space
Serous Pericardium (visceral layer)
Myocardium (muscle layer)
Endocardium

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STRUCTURES WITHIN A CRADIOMYOCYTE
The T tubules are always found at the Z disks, points of attachment for the _____ ________

Thin filaments

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what type of muscle is the cardiac muscle

striated

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what type of cell is in abundance in a cardiac muscle

mitochondria

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Ventricular myocytes are what kind of shaped

“brick shaped”

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mitochondria are mainly situated next to what structure in the cardiomyocyte

A band (thick filament)

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STRUCTURE OF CARDIOMYOCYTE Cardiac fibres are ______

branched

STRUCTURE OF CARDIOMYOCYTE why are cardiac fibres branched?

creates meshwork to withstand high pressure Intercalated discs provide strong mechanical adhesion allows electrical conduct and depolarisation to flow over the heart rapidly connected to more than one cell

INTERCALATED DISC Three main structures

Desmosome Adherens Junction Gap Junction

what does the desmosome function as

function as a cell anchor

what does the adherense junction function as

provide cell strength

what does the gap junction function as

couples cell electrically and metabolically

intercalated discs and branched myocytes both aid strength ______ and _______

contractility and conductivity

fibres form cross ______ for efficient pumping and strength

cross helices

Calcium and contraction if you remove calcium, the heart loses the ability to ______ in cardiac muscle

contract

calcium and contraction in skeletal muscle , when Ca is removed what happens

can survive without Ca for 25 mins

ion pumps require what to function

ATP

why do Ion pumps require ATP

ions are driven by metabolic energy usually against their conc gradient

in Ion exchangers/symports, how does it work

ions are driven by prevailing gradients (usually exploiting the energy in the transmembrane Na gradient)

how do ion channels work

ions move down their conc gradient

How is the electrical signal of the action potential sent to the intracellular Ca stores (the SR) to initiate Ca release. Where does this occur

At the dyad

How is the electrical signal of the action potential sent to the intracellular Ca stores (the SR) to initiate Ca release. AP from adjacent cell travels down where

T tubule

How is the electrical signal of the action potential sent to the intracellular Ca stores (the SR) to initiate Ca release. AP from adjacent cell travels down T tubule, and contains what

clusters of L-type Ca channels (voltage activated)

How is the electrical signal of the action potential sent to the intracellular Ca stores (the SR) to initiate Ca release. AP from adjacent cell travels down T tubule, and contains clusters of L-type Ca channels (voltage activated), the SR membrane close to what

T tubule

how is the electrical signal of the AP sent to the intracellular Ca stores (the SR) to initiate Ca release . Ca release channels of the junctional are positioned under the Ca channels of the __ _____

T tubule

how is the electrical signal of the AP sent to the intracellular Ca stores (the SR) to initiate Ca release . Ca release channels of the junctional are positioned under the Ca channels of the T tubule, trigger SR calcium release from what receptors

Ryanodine

relaxed sarcomere is measured at what

2um

contracted sarcomere is measured as what

1.6um

INTER-RELATIONSHIP BETWEEN MYOFILAMENT PROTEINS ATP releases myosin ____

head

INTER-RELATIONSHIP BETWEEN MYOFILAMENT PROTEINS Tropomyosin helps the ______ move

troponin

INTER-RELATIONSHIP BETWEEN MYOFILAMENT PROTEINS Mg allowed for the ______

disengagement

ATP activates that myosin and Mg allows for the _______

disengagment

Arrange the Troponin subunits

I C T

Ca binds to the myofilaments (troponin __) to allow for what

Troponin C to allow for cross bridge formation and contraxtion

Briefly explain the Frank-Starling Law of the Heart

Otto - peak systolic pressure in the frog heart is directly related to resting (diastolic) fibre length Ernest-Starling: cardiac output is directly related to filing pressure

increase resting tension = more strength of the heart = more ability for the heart to ______

contract (elastic band)

The heart has how many ways to increase contraction

what are the 2 ways to increase contraction

increasing sarcomere length causes 1. increased cross-bridge overlap 2. increased Ca sensitivity of myofilaments (troponin C)

Cardiac cycle - the heart (pressure volume loop) Relaxation of ventricles to allow ____

atrium to fill with blood

what are the 5 letters in the ECG

P Q R S T

what causes stretch on the heart (2)

preload pressure from other organs lung/respiration