Physiology Test 5
Energy is released when __________.
ATP is broken down into ADP and a phosphate molecule
The cell bodies of upper motor neurons are located in the __________, while the cell bodies of lower motor neurons are located in the __________
brain; spinal cord
The structures responsible for monitoring muscle tension in the tendons during muscle contraction are __________.
golgi tendon organs
The stretch reflex is a called a ____________ reflex because the sensory neuron synapses directly with the motor neuron, rather than synapsing via an interneuron.
monosynaptic
Each somatic motor neuron, together with all of the muscle fibers it innervates, is called a ____________.
motor unit
Sprinters working at 100% of their aerobic capacity for 45 seconds obtain most of their energy from __________.
muscle glycogen
During contraction of a muscle, calcium ions bind to __________.
the troponin molecule
An action potential spreads throughout a muscle fiber __________.
via the T-tubules
Pair the skeletal muscle fiber type with its corresponding description.
1. High oxidative capacity for aerobic respiration; also called "slow oxidative fibers" -> Type 1 Fibers 2.Metabolize anaerobically; also called fast-twitch fibers -> Type 2 Fibers 3.Fast-twitch fibers that also have a high oxidative capacity; also called fast oxidative fibers -> Type 2A Fibers
Match the term regarding exercise training with the correct description.
1. The maximum rate of oxygen consumption in the body -> aerobic capacity 2. The percentage of the oxygen uptake at which a significant rise in blood lactate levels occurs -> lactate threshold 3. Reversible, exercise-induced reduced ability in the muscle to generate force -> muscle fatigue
Match the type of muscle contraction to its description.
1. muscle tension causing shortening -> concentric contraction 2. muscle tension does not cause shortening of the muscle -> isometric contraction 3. lengthening contraction -> eccentric contraction
Match the description of the skeletal muscle structure with its name.
1. surrounds the entire skeletal muscle -> epimysium 2. surrounds a skeletal muscle fascicle -> perimysium 3. surrounds a skeletal muscle fiber -> endomysium
Skeletal muscles are able to generate their greatest force during a contraction when their length is ____________ of their normal resting length.
100-120%
After 3 hours of exercise what are the main sources of energy?
Blood glucose and plasma free fatty acids
Check all the characteristic of cardiac muscle tissue.
Cells are striated; Gap junctions join adjacent cells; Under autonomic control
To demonstrate an understanding of the rates at which maximum tension is developed in skeletal muscles, utilize the image below to match the skeletal muscle fiber types with the activity most likely to utilize those fibers.
Fast glycolytic -> jumping onto a high ledge Slow Oxidative -> walk in the woods with friends Fast Oxidative -> half mile race
Where are most plasma-free fatty acids obtained from?
Hydrolysis of stored adipose tissue
Which of the following shortens in length during skeletal muscle contraction?
I band
Check all the structures that shorten during a skeletal muscle contraction to test your knowledge of the sliding filament theory.
I band; H band; sarcomere
Choose the correct statement regarding reciprocal innervation and the crossed-extensor reflex.
If the left foot steps onto a nail, the extensor muscles of the right leg will contract to maintain balance.
Which of the following describes cardiac muscle fibers? Check all that apply.
Involuntary; Striated; Under autonomic control
How do the A and I bands change during muscle contraction?
The A band remains the same and the I band narrows.
How do the H bands and I bands of the sarcomere differ?
The H bands contain only myosin, while the I bands contain only actin.
What structures do the calcium ions bind to when muscle contraction is initiated?
The troponin molecule
Which of the following statements about the "heads" of the myosin filament is correct?
They can attach to different sites on the actin filament
What happens to the amount of plasma-free fatty acids used for energy as exercise continues?
They increase, as stored adipose tissue is hydrolyzed for energy.
Match the characteristics with the skeletal muscle fiber type.
Type 1: slowest shortening speed Type 2A: Intermediate Glycogen Content Type 2X: Fewest Capillaries Type 2 (or 1..if he doesn't fix the typo): Highest glycogen content
Check all of the characteristics of smooth muscle tissue structure and function.
Under autonomic control; Many more thin than thick filaments; Capable of producing graded depolarization and contractions
The bond between the actin and myosin head is broken when __________.
an ATP molecule binds to the myosin head
As a person engages in exercise over several hours, muscle glycogen stores __________.
decrease, as exercising muscle utilizes a both glucose and free fatty acids for energy
As actin and myosin filaments slide past each other during muscle contraction, __________.
neither actin nor myosin filaments shorten
A person continues breathing heavily for some time after exercising in order to repay an oxygen "debt." This oxygen debt allows for __________,
replenishment of oxygen stored in the myoglobin of the muscle cell
If a muscle is already 80% shorter than its resting length, it cannot be stimulated to contract any more because __________.
the Z lines abut against the thick filaments and cannot move any further
Cross bridges form between __________.
the actin filaments and the myosin heads