Card Set Information
Striated and Cardiac muscle
A myofibril is a part of, is comprised by?
Sarcomeres are made of, demarked by?
: Thick Filaments
: Thin filaments
How does contraction change the sarcomeres?
No change in A band (length of myosin filament)
Shortening of I band (end of one myosin to end of other myosin(of next sarcomere))
Shortening of H zone (end of one actin to the other(within same sarcomere)).
Where is most Ca stored in muscle?
Terminal Cisternae of Sarcoplasmic reticulum, near the T-tubular system.
What proteins make up the thin filaments?
: structural component, contains attachements for cross-bridges
: covers attachement sites, moves to allow cross-bridging
: binds calcium to move troponin-tropomyosin complex.
What three subunits make up troponin?
: binds tropomyosin
: Inhibits myosin binding to actin
: binds calcium.
When is contraction terminated?
When Ca is removed from troponin.
What protein makes up the thick filaments?
Possesses cross bridges, which have ATPase activity.
What causes dissociation of the cross bridge?
Binding of ATP.
Cross-bridge cycling will continue until?
Withdrawal of Ca
: normal resting muscle
Depletion of ATP
: Rigor Mortis.
Which two ATPases are involved in contraction?
: energy for mechanical contraction
: Sarcoplasmic endoplasmic reticulum calcium-dependent ATPase - provides energy for termination of contraction by pumping Ca back into depot.
How is tetanus reached?
There is sufficient free Ca for continuous cycling of all cross-bridges.
What is summation?
Increased frequency of APs --> increased Ca released --> increased magnitude of response
Possible because of very short refractory period.
What are the two types of tension on a muscle?
Preload on a muscle increases what?
What does the magnitude of developed active tension depend on?
Number of cross-bridges that cycle.
What are the characteristics of white muscle?
Large mass, short term use
High ATPase activity (fast)
High capacity for anaerobic glycolysis
What are the characteristics of red muscle?
Small mass, long term use
Low ATPase activity (slow)
High capacity for aerobic metabolism (mitochondria)
High myoglobin (red color).
What are the two direct indices of ventricular preload?
: Left ventricular end-diastolic volume
: Left ventricular end-diastolic pressure.
What are the three indirect indices of ventricular preload?
Left Atrial pressure
Pulmonary Venous pressure
Pulmonary capillary wedge pressure (swan-ganz).
Acute changes in contractility are usually due to?
Changes in intracellular dynamics of Calcium.
Increased sympathetic activity to the heart will produce?
Decreased systolic interval
: contractility effect
Decreased diastolic interval
: heart rate effect.
What would result in a loss in preload?
Loss in contractility?
Increase of contractility?
Increase of preload?
What determines Cardiac Output (CO), venous or arterial parameters?
Stroke Volume (SV)=?
Ejection Fraction (EF)=?
Cardiac Output (CO)=?
CO= SV x HR.
what is systolic dysfunction?
Abnormal reduction in ventricular emptying (increased afterload).
What is diastolic dysfunction?
Abnormal ventricular filling (stiffened ventricular wall s/p MI).
What is, causes concentric hypertrophy?
Chronic pressure overload
Dramatic Increase in wall thickness, decrease in chamber diameter
: decreased ventricular compliance -> diastolic dysfunction, eventually systolic dysfunction.
What is, causes eccentric hypertrophy?
Chronic Volume overload (eg. MR, AR, PDA)
Modest increse in wall thickness, no change in chamber diameter
: systolic dysfunction -- compliance of ventricle uncompromised.
What are the three types of cardiomyopathies?
: Dilation without compensation in wall thickness
: Decreased ventricular compliance
: most common assymmetric hypertrophy of septum.