Cardiac muscle

heart

how is cardiac like the skeletal?

Ca2+ → troponin → more tropomyosin → so myosin binds → actin

how is cardiac muscle like fatty acids

oxidative metabolism

many mitochondria

describe heart myosin

cardiac myosin

10 times slower than skeletal

how is the heart self-starting

pacemaker

does the heart have recruitment, tetany, or fatigue

no, it is pacemaker

what kind of channels does the heart have

gap junctions

• prevent recruitment

what is technically the pacemaker

sino-atrial (SA) node

describe the pacemaker potential

(graph)

all or none, every cell is excited to contract every time

graph goes down, K+ out

graph goes up, Ca2+ (leak) and Na+ go in

no resting potential

what are the steps of the pacemaker, heart conduction system

SA node (pacemaker potential) → atrial muscle → AV node → bundle of His → Bundle of branches → Purkinjie fibers → ventricle muscle

cardiac muscle cell potential

(graph)

Na+ goes into cell

Ca2+ goes into cell

• Ca2+ for contraction, comes from extra cellular fluid (ECF) not sarcoplasmic recticulum

K+ goes out, Ca2+ plateau = refractory period

• prevent tetany, no 2nd AP

where does the Ca2+ come from

the extra cellular fluid (NOT sarcoplasmic recticulum)

what does the refractory period prevent

tetany, no 2nd AP

does the heart fatigue

no it rests between beats

what changes the heart rate

the pacemaker

what changes the heart force

the fill volume (every cell works harder)

what is the pacemaker BPM

75 beats per min

0.8sec

decrease leak equals

more time in between beats

• G-protein down, more K+ out

• AcH

• parasympathetic

during sympathetic, the force vs time would

have more BPM

• less time in between beats

• lots ok Ca2+ leak

what is frank-starling law of the heart

at end diastalsis, volume increases, the force of heart beat increases

diastolic is

rest time of the heart

systolic is

contraction time of the heart

EDV is?

End Diastolic Volume

max fill of heart just before contraction (intrinsic mechanism)

when the volume goes up what happens to sarcomere

stretch increases

what happens when theres more blood to the heart

• sympathetic

• exercise

• relax/slow down means more fill time, and more blood

“in vivo” means

beats 25-43 BPM, CN X (vagus nerve) 

• basal parasympathetic

• pacemaker

“in vitro” means

45-60 BPM

pacemaker

in humans SA is about ~

100 BMP 70-80

• basal sympathetic