Pool Questions 4 Flashcards
(40 cards)
Maximum power and maximum efficiency occurs at what percentage of maximum velocity?
⅓ max velocity
What is the definition of a motor unit?
A motor neuron and all the fibers it innervates
What is the difference between the epimysium, perimysium and endomysium?
Epimysium is the connective tissue around the muscle, perimysium is the connective tissue around bundles of muscle fibers (fascicle), endomysium is the connective tissue around individual muscle fibers.
What is a triad? Each sarcomere has how many triads?
A triad is a triple layer structure with two sacs of sarcoplasmic reticulum called cisternae with a T Tubule in the middle. 2 triads per sarcomere
What determines the speed of contraction?
The amount of fibers dedicated to the movement as well as the composition of the fibers (aka more fast twitch fibers vs slow twitch). Amount of ATPase is another key-factor. fast twitch have more ATPase.
T/F-During contraction, the length of myosin does not change.
True
What is the mechanism of Excitation Contraction Coupling?
Action potential on an alpha-motor neuron. Acetylcholine is released and binds to the sarcolemma. Action potential down the sarcolemma which then goes to the T-tubules. Calcium is released from the SR. Calcium then binds to troponin. Myosin binding sites appears when calcium attaches to TPN and lets go of actin. Myosin head automatically binds to actin. Hydrolysis of ATP enables power-stroke. Shortening of the Z lines. Another hydrolysis of ATP enables a release of the myosin head from actin.
What % of cardiac cells generate action potentials spontaneously?
1%
T/F- The heart requires action potentials from neurons or other signaling mechanisms in order for the SA Node to initiate contraction electrically.
False-internally spontaneous, is its own pace maker
Write out the route of cardiac AP flow starting with the SA node.
SA Node, bundle of bachmann, internodal tracts, AV node, bundle of his, purkinje fibers
Explain why the SA Node is the “pacemaker” of the heart. Why does the AP initiate there?
Depolarization occurs quickest in the SA node
Which layer of the heart wall forms the bulk of the heart?
Myocardium
Cardiac output is defined as
the amount of blood pumped through the heart in one minute.
- Brachiocephalic Trunk
- Superior Vena Cava
- Aortic Valve
- Pulmonary Semilunar valve
- Right Atrium
- Papillary muscles
- Left common carotid artery
- Left subclavian artery
- Aorta
- Pulmonary Artery
- Pulmonary Vein
- Left Atrium
- Chordae Tendinae
Given a stroke volume of 80ml and a cardiac output of 5500ml, determine the corresponding heart rate.
CO (Q)=SV*HR
5500=80*HR
HR=68.75 beats/minute
Blood Volume in the body is approximately
5-6 L
This part of the heart anchors the heart to the surrounding structures and prevents overfilling.
Pericardium
Which portion of the ECG represents atrial depolarization?
P wave
Which muscle fiber type has the largest cross sectional area of fiber?
Type IIx fast twitch; greater the cross sectional area of the fiber the greater the force and speed it can generate
Compare the differences in stroke volume and heart rate of a sedentary individual at rest to an endurance trained individual at rest.
Sedentary SV: 70-80mL, Trained SV: 120-130mL
Trained SV is much larger because they have the same cardiac output but the heart is more efficient at pumping blood with less work (aka lower HR)
HR: Sedentary: 70 bpm, Trained: 40-50 bpm
On the length tension curve, what is the length where no more cross bridges are formed
3.7 micrometers
On the length tension curve, what is the length of actin?
1.05 micrometers
On the length tension curve, what is the length of myosin?
1.6 micrometers (um)
How many liters of blood does the body hold? How many can it hold?
5-6 L on average but can hold 12-15L
