Histo Lecture 1

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What are intercalated discs?
- -Junction between adjacent myocardial cells
- -Contain gap junctions for easy ionic conductance
Mitochondria make up how much of the sarcoplasm?

40%
What is the major fuel for cardiac cells?
- Fatty acids
- Minimal amount of glycogen present
Myocytes are connected by what?

Gap junctions
What do gap junctions allow in the heart?
- Ionic conductance between cells
- Allows syncytium
What are the five differences between cardiac and skeletal muscle?
- Gap junctions
- Intercalated discs
- Single nucleus
- Less developed SR and T-tubules
- Autonomic innervation
Define syncytium
- Multinucleate mass of cytoplasm resulting from the fusion of cells
- -Depolarization travels as a "wave" throughout the myocardium
- -Impulse to one area of heart results in contraction of entire myocardium
Syncytia portions (atria/ventricles) are separated by what?

The fibrous "ring" tissue surrounding the AV valves
Fibrous ring prevents what?
- Conduction of impulse from atria to ventricles
- -Allows atria and ventricles to contract separately
A plateau in an action potential is cause by what?

"Slow" calcium channels that remain open longer than sodium channels
Why is there a delayed repolarization period in cardiac muscle?

Caused by delayed movement of K+ out of cell
What is Systole?
- Ventricular contraction
- Heart ejects blood into pulmonary and systemic circulation
What is Diastole?
- Ventricular relaxation
- Atria and ventricles fill with blood
What is mean arterial blood pressure (MABP)?

Average pressure exerted by the blood against the walls of systemic arteries

Author

paffman7

58991

Card Set

Histo Lecture 1

Description

Intro to Heart

Updated

2011-01-31T00:36:20Z

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