Cardiac and Smooth Muscle

Question 1

Cardiac muscle characterization?

Answer 1

striated
involuntary
muscle fibres = chain of cells

Question 2

Cardiac muscle fiber appearance?

Answer 2

striations with branching
intercalated disks
central nucleus

Question 3

Sarcoplasmic reticulum structure of cardiac muscles?

Answer 3

less well developed SR and terminal cisternae
T-tubule at Z-line (not A-I junction)
diad – SR + T-tubule

Question 4

Intercalated disks portions and function?

Answer 4

conduct electrical signal from one cell to another
Transverse portion
- adherens junctions, desmosomes, gap junctions
Longitudinal portion
- desmosomes, gap junctions

Question 5

What is a hypertrophic heart?

Answer 5

thickened ventricles
inefficient at blood pumping

Question 6

Smooth muscle characterization?

Answer 6

smooth
involuntary
muscle fiber = cell

Question 7

Smooth muscle appearance?

Answer 7

fusiform shaped cell
mono-nucleated – central location
wavy eosinophilic

Question 8

smooth muscle contraction?

Answer 8

• no sarcomere organization
• dense bodies bind actin
• nuclei = corkscrew

Question 9

Caveolae and smooth muscle contraction?

Answer 9

• Ca2 release from SR and enter from caveolae
• calcium-calmodulin complex activates myosin light chain kinase
• phosphate to myosin = expose actin binding site
• binds to actin = contraction