PSIO 201 EXAM 3 EXAMINATION STUDY
SHEET 2026 VERIFIED QUESTION–ANSWER
COLLECTION
◉ spatial summation
Answer: - muscles typically contain many motor units
- by activating ('recruiting') increasing numbers of motor units,
tension can be increased
◉ Size Principle
Answer: - the first motor units recruited are small (innervate few
fibers)
- the result is fine, carefully controlled increase in tension
- as more force is required, the larger motor units are recruited
◉ The vesicles inside the synaptic end bulb contain what?
Answer: acetylcholine
◉ What responds to action potentials?
Answer: muscle fibers
,◉ What happens at the synaptic end bulb when the action potential
gets there?
Answer: calcium enters the terminal releasing acetylcholine
◉ What goes inside the muscle fiber?
Answer: sodium
◉ When an action potential goes into the T-tubule what does it
cause?
Answer: release of calcium at the sarcoplasmic reticulum
◉ Myofibrils are attached to the sarcolemma via...
Answer: dystrophin- transfers the force from the sarcolemma to the
connective tissue outside the sarcolemma (endomysium)
◉ Isometric Contraction
Answer: 'same length'
- muscles generates tension but does not shorten
- every contract begins isometrically
- *sarcomeres are still shortening
◉ Isotonic Contraction
, Answer: 'same tension'
- after sufficient tension is generated to move the 'load' the muscle
changes length
- Two types: 1) concentric 2)eccentric
◉ Are sarcomeres shortening during an isometric contraction?
Answer: yes
◉ Concentric Contraction
Answer: effort > load
- when developed tension is sufficient to move the load, the muscle
shortens
◉ Eccentric Contraction
Answer: load > effort
- as tension decreases and the load exceeds tension, the muscle
lengths (ex. lowering the weight in a controlled fashion)
◉ All muscle actions are based on what type of contraction?
Answer: concentric
◉ How does the nervous system increase force?
SHEET 2026 VERIFIED QUESTION–ANSWER
COLLECTION
◉ spatial summation
Answer: - muscles typically contain many motor units
- by activating ('recruiting') increasing numbers of motor units,
tension can be increased
◉ Size Principle
Answer: - the first motor units recruited are small (innervate few
fibers)
- the result is fine, carefully controlled increase in tension
- as more force is required, the larger motor units are recruited
◉ The vesicles inside the synaptic end bulb contain what?
Answer: acetylcholine
◉ What responds to action potentials?
Answer: muscle fibers
,◉ What happens at the synaptic end bulb when the action potential
gets there?
Answer: calcium enters the terminal releasing acetylcholine
◉ What goes inside the muscle fiber?
Answer: sodium
◉ When an action potential goes into the T-tubule what does it
cause?
Answer: release of calcium at the sarcoplasmic reticulum
◉ Myofibrils are attached to the sarcolemma via...
Answer: dystrophin- transfers the force from the sarcolemma to the
connective tissue outside the sarcolemma (endomysium)
◉ Isometric Contraction
Answer: 'same length'
- muscles generates tension but does not shorten
- every contract begins isometrically
- *sarcomeres are still shortening
◉ Isotonic Contraction
, Answer: 'same tension'
- after sufficient tension is generated to move the 'load' the muscle
changes length
- Two types: 1) concentric 2)eccentric
◉ Are sarcomeres shortening during an isometric contraction?
Answer: yes
◉ Concentric Contraction
Answer: effort > load
- when developed tension is sufficient to move the load, the muscle
shortens
◉ Eccentric Contraction
Answer: load > effort
- as tension decreases and the load exceeds tension, the muscle
lengths (ex. lowering the weight in a controlled fashion)
◉ All muscle actions are based on what type of contraction?
Answer: concentric
◉ How does the nervous system increase force?
