E-C Coupling HeartLab Flashcards
Strcutures of myosin, actin, Myofibrils
Where are the electrical signals that control the heart generated from
the heart itself
what is the heart able to do in the absence of stimuli and what is this called
beating rhythmically
auto-rhythm
what is the structure of cardiac muscle
striated
each muscle fibre (cell) contains many what
Myofibrils
Each muscle fibre (cell) contains many myofibrils, these are the _________ units of the muscle
contractile
the actin (thin filaments) causes what appearance in myofibrils and fibres
lighter
the myocin (thick filaments) causes what appearance in myofibrils and fibres
darker
within each myofibril: actin and myocin are arranged into what
sarcomeres
which two junctions connect cardiac muscle cells
desmosomes and gap junctions
there are no what in cardiac muscles
NMJs
there are no NMJs in cardiac muscle but cardiac myocytes are electrically coupled by what
gap junctions
Gap Junctions are protein channels which form low resistance electrical communication pathways between what
neighbouring myocytes
Gap Junctions ensure that each electrical excitation reaches all the cardiac myocytes, what law is this known as
All or none law of the heart
The desmosomes within the intercalated discs provide what between adjacent cardiac cells
mechanical adhesion
Desmosomes ensure that the tension developed by one cell is what
transmitted to the next
Myosin chains are composed of two heavy chains arranged in what structure
head and tail
the myosin chains wrap around eachother to form what
double helix structure for the tail
the free ends of the myosin chan form what
the head
each myosin complex has _ light chains, two associated with each head
four
several myosin chains from the myosin filament (the ______ filament)
thick
the head (cross birdges) protrude from where
the arm
The myosin heads will interact with what
the actin filaments
what binding sites are available on the myosin head
ATP binding sites
Actin is composed of how many F actin strands
two
What forms the troponin complex
Troponin T
Troponin I
Troponin C
how is the tropomyosin arranged around the actin
in a double helix
G actin has the bind site for what
the myosin head
In the troponin complex, the different troponins are attached to different structures:
Troponin T:
Troponin I:
Troponin C:
Troponin T: tropomyosin
Troponin I: G-actin
Troponin C: contains the Ca2+ binding site
In the absense of Ca2+, the binding site for myosin on actin are covered by what
Tropomyosin
Ca2+ binds to Troponin C, changing what of the troponin complex
When CA2+ binds to the Troponin C, the complex of the troponin complex is changed
When Ca2+ binds to Troponin C, the conformation change in the Tropnin complex pulls tropomyosin away from ______, exposing the myosin binding sites
G-actin
When Ca2+ binds to Troponin C, the conformation change in the Tropnin complex pulls tropomyosin away from the G-actin, exposing what
the myosin binding sites
