Inherent Properties of the Heart Flashcards
What are the 4 main properties of the heart
CERC
Rhythmicity
Excitability
Conductivity
Contractibility
which ventricle does the most work in the heart, and why
Left Ventricle, pumps blood to most of the body
Which ventricle pumps blood to the lung
Right Ventricle
if there was an issue with blood supply to the lung, which chamber of the heart does this correspond with
Right Ventricle
what do you start losing after a MI
layers of the heart, heart becomes weaker
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
what are the 3 main layers of the heart
Pericardium
Myocardium
Endocardium
what is the most outer protective layer of the heart
Pericardium
what is the role of the pericardium
Prevents cardiac Distention and excessive movement
Lubricant
what is the middle layer of the heart
Myocardium
what is the role of the myocardium
synchronised contraction and relaxation of the heart
What is the innermost layer of the heart
Endocardium
what is the role of the endocardium
lines the heart
reduces friction of blood flow in chambers
conduction system
what is the layer in the heart the lining covering the trabeculae
Endocardium
what type of connective tissue lies between the pericardium and the myocardium
subendothelial layer - thin collagen fibres
Sub-cardiac layer - thick collagen fibres
which layer is the muscle layer
myocardium
STRUCTURES WITHIN A CARDIOMYOCYTE
The T tubules are always found at the ___ disks
Z
describe an intercalated disc
form the staircase pattern, they act as anchoring points for the muscle fibres (filaments)
layers of the heart from superficial to deep
Fibrous Pericardium
Serous Pericardium (parietal layer)
Space
Serous Pericardium (visceral layer)
Myocardium (muscle layer)
Endocardium
STRUCTURES WITHIN A CRADIOMYOCYTE
The T tubules are always found at the Z disks, points of attachment for the _____ ________
Thin filaments
what type of muscle is the cardiac muscle
striated
what type of cell is in abundance in a cardiac muscle
mitochondria
Ventricular myocytes are what kind of shaped
“brick shaped”
mitochondria are mainly situated next to what structure in the cardiomyocyte
A band (thick filament)
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
2
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
