cardiac muscle

lesson two unit 3 week 8

majority of the heart is made up of what muscle cell

majority of the heart is made up of cardiac muscle cells, known as cardiomyocytes

what are the two types of the cardiomyocytes

• contractile cells: responsible for pumping blood thru the heart

• nodal/conducting cells: responsible for spreading electrical activity thru the heart

You see a branched cell under a microscope that is contracting. this cell must be producing atp. true or false

true

You see a branched cell under a microscope that is contracting. This cell must be receiving ap from the motor neuron. true or false

true

where does the calcium involved in contracting a muscle come from in the cardiomyocyte

calcium comes from in from the outside (extracellular fluid), across plasma membrane, thru ion channels, down concentration gradient, helping release calcium from sr

the process of calcium coming in to help release calcium, what is that called?

calcium induced calcium release

why do cardiomyocytes have lots of mitochondria

bc the heart is made up of cardiomyotcyes, it always needs atp to be made to keep working.

what are the three things needed for the cardiomyocyte to contract

atp, ap (nodal cells creates ap which are within the heart itself, no neurons needed), and calcium

how do cardiomyocytes communicate

one cell communicates directly with its neighbouring cell by protein channels calls gap junctions (electrically connected) ex: if cell 1 has an ap, that ap (ions) moves into cell 2thru gap junctions

what is the basic structure of a cardiomyocyte

myofibrils (myofilament) intercalated discs, desmosomes, and gap junctions

what is the function of the intercalated discs

locks the two cells together (humps to lock in shape like puzzle pieces) by special proteins called desmosomes (like glue)

what are the characteristics/functions of nodal and conducting cells

• dont have a lot of actin and myosin—therefore they dont contract unlike the contractile cells of the heart

• responsible for taking ap and carrying it thruout the heart

• self excitable-creates its own ap