Force generation by the heart Flashcards
what type of muscle is cardiac muscle?
striated
what is the striation caused by?
reglular arrangement of contractile protein
what are the junctions in the heart like?
There is no neuromuscular junctions in the cardiac muscle
But, the cardiac myocytes are electrically coupled by gap junctions
what are gap junctions?
These are protein channels which forms low resistance electrical communication pathways between neighbouring myocytes
what does the presence of these gap junctions allow?
They ensure that each electrical excitation reaches all the cardiac myocyctes
what law is this?
all or none law
what are the other junctions in the heart?
desmosomes
what do the desmosomes do?
provide mechanical adhesion between adjacent cardiac cells
what do desmosomes ensure?
They ensure that the tension developed by one cell is transmitted to the next
where are the dermosomes located?
within the intercalated discs
what does each muscle fibre (one cell) contain many of?
myofibrils.
what are myofibrils ?
the contractile unit of the muscle
describe the myofibrils?
they have alternating segments of thick and thin protein filaments
what makes up the thin filaments and what do they look like?
The ACTIN (thin filaments) causes the lighter appearance in myofibrils and fibers
what makes up the thick filaments and what do they look like?
MYOCYIN (thick filaments) causes the darker appearance
what is the arrangement of actin and myocin called in myofibrils?
sarcomeres
what is a sarcomere?
the smallest functional unit of the heart
how is muscle tension generate?
by sliding the actin filaments on myocin filaments
what does force generation depend on ?
ATP dependent interaction between actin and myocin
Energy is stored in the myocin head but even if ADP and Pi are attached and the head is energised you need another component, what is this?
calcium
what other process involving cross bridges do you need ATP for?
breaking the bridges down