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PDF Download FREE AND STUDY GAMES ABOUT A&P LECT. EXAM
QUESTIONS
Actual Qs and Ans Expert-Verified Explanation
This Exam contains:
-Guarantee passing score -54 Questions and Answers -format set of multiple-choice -Expert-Verified Explanation
Question 1: size of active motor units
Answer:
Large motor units produce stronger contractions than small ones.
Question 2: 2 forms of isotonic contraction
Answer:
concentric and eccentric
Question 3: relaxation
Answer:
When its work is done, a muscle fiber relaxes and returns to its resting length
Question 4: muscle size
Answer:
The strength of a muscle depends primarily on its size; this is why weight lifting increases the size and strength of a muscle simultaneously. A muscle can exert a tension of about 3 to 4 kg per sq cm of cross-sectional area.
Question 5: contraction step 10:
Answer:
myosin head must have ATP molecule bound to initiate contraction process. Myosin ATPase hydrolyzes this ATP into ADP & phosphate (Pi). The energy released by this process activates the head, which "cocks" into an extended, high-energy position
Question 6: muscle fatigue
Answer:
the progressive weakness and loss of contractility that results from prolonged use of the muscles.
Question 7: complete (fused) tetanus
Answer:
At a still higher frequency, such as 40 to 50 stimuli/s, the muscle has no time to relax at all between stimuli, and the twitches fuse into a smooth, prolonged contraction Question 8: steps of excitation 3:
Answer:
ACh diffuses across the synaptic cleft and binds to receptor proteins on the sarcolemma.
Question 9: creatine kinase
Answer:
obtains P i from a phosphate-storage molecule, creatine phosphate (CP), and donates it to ADP to make ATP. This is a fast-acting system that helps to maintain the ATP level while other ATP-generating mechanisms are being activated.
Question 10: incomplete tetanus
Answer:
Wave is added upon wave, so each twitch reaches a higher level of tension than the one before, and the muscle relaxes only partially between stimuli. This effect produces a state of sustained fluttering contraction called Question 11: steps of excitation 4:
Answer:
- ACh molecules must bind to each receptor to open the channel. then Na+ diffuses into cell & K+
diffuses out and goes through end-plate potentials (EPP)
Question 12: cardiac and smooth muscle are
Answer:
involuntary muscles Question 13: excitation steps continue 7:
Answer:
Action potentials open voltage-gated ion channels in T tubules; they r physically linked 2 calcium channels in terminal cisternae of sarcoplasmic reticulum;thus channels in SR open & calcium diffuses out of SR down its concentration gradient& into cytosol
Question 14: latent period
Answer:
delay
Question 15: treppe
Answer:
pattern of increasing tension with repetitive stimulation Question 16: contraction step 13:
Answer:
The binding of ATP to myosin destabilizes myosin-actin bond(breaking cross-bridge) myosin molecule is now prepared to repeat process;it will hydrolyze ATP, recock, attach to new active site farther down the thin filament, and produce another power stroke.Question 17: excitation steps continue 6:
Answer:
A wave of action potentials spreads from the end plate in all directions, like ripples on a pond. When this wave of excitation reaches the T tubules, it continues down them into the sarcoplasm Question 18: steps of excitation 5:
Answer:
Areas of sarcolemma next 2 motor end plate have voltage-gated ion channels that open in response 2 EPP. Some r specific for Na+ & admit it 2 cell while others r specific for K+ & allow it to leave; thus create action potential; muscle fiber is now excited
Question 19: relaxation step 16:
Answer:
Active transport pumps in the SR begin to pump Ca2+ from the cytosol back into the cisternae. Here, the calcium binds to a protein called calsequestrin (CAL-see-QUES-trin) and is stored until the fiber is stimulated again.
Question 20: contraction phase
Answer:
Once the elastic components are taut, the muscle begins to produce external tension and move a resisting object, or load.
Question 21: fascicle arrangement
Answer:
Pennate muscles such as the quadriceps femoris are stronger than parallel muscles such as the sartorius, which in turn are stronger than circular muscles such as the orbicularis oculi.
Question 22: contraction
Answer:
the step in which the muscle fiber develops tension and may shorten Question 23: relaxation step 15:
Answer:
AChE breaks it down in2 frgmnts that cant stimulate muscle;synaptic knob reabsorbs frgmnts but when nerve signals stop no new ACh is released 2 replace that which is broken down;stimulation of muscle fiber stops Question 24: relaxation step 17:
Answer:
As calcium ions dissociate from troponin, they are pumped into the SR and are not replaced.Question 25: excitation steps continue 8:
Answer:
Calcium binds to the troponin of the thin filaments.
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