Lecture 9 Flashcards
How does excitation contraction coupling occur at the cellular level?
The cell depolarises the cell membrane from -80mV to +10mV where it excites the contractions for the cell
What does electrolyte excitation elevate?
Cytoplasmic ca2+ in the cell, interacts with the myofilament proteins of the cell to give the resulting contraction
What does the structure of the ventricular cardiomyocytes mean?
Proves the function - ca2+ contraction
What type of muscle are heart muscles?
Striated heart muscle
What is found in striated heart muscle?
Lots of mitochondria
Why are heart muscles called striated muscles?
Because they have alternative light and dark banding
What are the light and dark bands?
Sarcomeric structures - striated parents of the cardiomyocytes
Why do striations occur?
Because of the rigid arrangements of the thick and thin filaments of the sarcomere structures
What are sarcomeres defined by?
Defined by the boundary of the Z lines
How far apart are the Z lines?
2 microns apart
What are Z lines?
Scaffolding structures that hold in place the thin filaments
What do you see in the middling portions?
Much more myofilament activity as this is where the invaginations of the thick and thin filaments are
What are sacromeric structures?
The individual contractile units within the cell - control with electrical excitation contraction
What is in the middle of the H zone?
The N line
What does the H zone do?
Holds the thick filament in place
What happens if the sarcomere shortens?
The whole cell shortens
What shape does the plasma Lamar make?
A cube - as it has right angle convolutions
Where do the T-tubular invaginations of the plasma lemma occur at?
Z lines
What do the 90 degree convolutions of the plasma lemma allow?
Allows the electrical citation to get deeper into teh cell to get closer to the sarcomeric units
What do the cardiomyocytes occur in?
They occur in unison, they occur in close proximity to the Z lines
What are the two structural specialisations of the cardiomycoyte?
Convolutions of the plasma lemma and the facilitation of CICR
Describe the facilitation of CICR in the cardiomyocytes?
Close positioning of the SR next to the t-tubule
What are the transverse T -tubules part of?
The Extracellualr part of the matrix
What is the double membrane system?
Developing from the T tubule cavity and SR
