KNES 466 Lecture Notes - Lecture 3: Cardiac Muscle, Skeletal Muscle, Cardiac Output

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KNES466 Lec 3
Cardiac Cells: Two questions
1. Structurally, is cardiac muscle similar to skeletal muscle?
a. Yes, similar in many structures, A band, etc.
b. Both striated
c. Both contain sarcolemma
d. Skeletal muscle are multinucleated vs. 1-2 central nucleated in cardiac cells
e. Cardiac cells are shorter and have intercalated discs
2. Does cardiac muscle show different fiber types?
Structures of cardiac cells:
Actin(thin)/myosin(thick) filaments, creates movement in power stroke, condensing cell
and producing force
Transverse tubule--facilitates entry of action potential, which travels surface of cardiac cell
and enters via t-tubule and go into cell.
o Has protein receptor which facilitates release of calcium
Sarcoplasmic reticulum-primary function is to store, release, reuptake calcium, which is
essential for contraction of cardiac cells
Difference between cardiac and skeletal
o Cardiac-Two receptors for proteins which facilitate release of calcium
Important because cardiac cells are vital for every function, number of
redundant mechanisms which contribute to maintenance of cardiac output.
o Cardiac-high concentration of mitochondria in cardiac muscle
Substantially greater than that of skeletal muscle
Side by side image analysis of cardiac vs muscle would be based on
mitochondria
Cardiac cells rely on aerobic energy processes, causing necessity for many
mitochondria
Syncytium--Ability for all the hearts cells to contract at the same time
STRUCTURE RELATES TO FUNCTION (Bruno Kisch, 1956)
Adaptations to exercise
Aerobic exercise training persons, skeletal muscle begins to resemble cardiac muscle to a
greater extent. Increase in oxidative enzymes, size of mitochondria, etc.
"The Tubes"-basic structure of blood vessels
Veins
o Endothelium and basement membrane making up lining to protect the inside of vein
o Tunica media, smooth muscle to alter diameter when necessary
o Unidirectional valves, only found in veins
Arteries
o Endothelium and basement membrane making up lining to protect the inside of vein
o Tunica media, smooth muscle to alter diameter when needed
Arterioles
o Endothelium and basement membrane making up lining to protect the inside of vein
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