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Anatomy Mod 5 Test

Anatomy

QuestionAnswer
The repeating unit of a myofibril. Sarcomere
The functional unit of the nervous system, a nerve cell. Neuron
The interface between a neuron and another cell. Synapse
A chemical released by a neuron, which diffuses across the synaptic cleft. enabling the neuron to communicate with another cell. Neurotransmitter
One motor neuron and all the muscle fibers it innervates. Motor unit
An individual muscle fiber contracts maximally in response to an action potential. All-or-none law of skeletal muscle contraction
A stimulus to small to create an action potential in a neuron. Subthreshold stimulus
A stimulus strong enough to create one action potential in a neuron. Threshold stimulus
Stimuli of increasing strength that create more action potentials along more neurons. Submaximal stimulus
A stimulus that is strong enough to create action potentials on all motor neurons to a particular muscle. Maximal stimulus
The state of partial contraction in a muscle, even when the muscle is not being used. Muscle tone
What are the 4 major functional characteristics of muscle tissue? Contractility, excitability, extensibility, elasticity.
What are the 3 types of muscle tissue? Cardiac, skeletal, smooth.
In terms of their nuclei, skeletal muscle fibers are different from most cells in two ways, What are those ways? They have multiple nuclei, and those nuclei are located in the cell but along the edge of the cell instead of in the center of the cell.
When a muscle fiber contracts, what happens to: The distance between the Z discs? The length of the A band? The length of the I bands? The length of the H zone? Shrinks. Remains the same. Shrinks. Shrinks.
The concentration of calcium in the sarcoplasmic reticulum is decreasing. Is the muscle fiber starting to contract or has it finished contracting? Starting.
The myosin heads of a sarcomere have just received a boost of energy. Is the power stroke or the return stroke about to happen? Return stroke. This is when ATP binds to them and breaks down into ADP + P and primes the myosin head getting it ready for the next cycle.
A myosin head has ADP attached to it but not an individual phosphate. Which is going to happen next the power stroke or the return stroke? Power stroke which will cause the ADP to be released.
If you could look at several muscle fibers while they were in action, how could you determine which fibers are part of the same motor unit? They will contract at the same time.
What is the function of acetylcholinesterase? If it were not for acetylcholinesterase, what would happen to a muscle fiber? It inactivates ACh. Muscles would stay contracted.
There are 2 major roles that ATP plays in muscle contraction and relaxation. The first involves the sarcoplasmic reticulum, while the second involves the myosin head. What are those 2 roles? ATP is required by the sarcoplasmic reticulum so that it can actively transport Ca2+ into itself (away from the actin), and it provides the energy for muscle contraction.
A muscle is stiff. It can neither contract nor relax. What is wrong in the sarcomere? What causes this? It is seizing up. Physiologically it is caused by the myosin heads remaining attached to the active sites on actin.
When a muscle fiber relaxes, does it automatically stretch back to its resting size? No. It must have gravity or an antagonist muscle.
A motor unit has just been recruited. What has just happened? It has contracted.
All of the motor units in a muscle have been recruited. If more stimulus is applied what is it called? Supramaximal stimulus.
A muscle is expending energy faster than it can be replaced by aerobic respiration. There is no creatine phosphate left. What can the muscle fiber do? Anaerobic respiration.
What will build up in the cell described in question 20? Lactic acid.
When we breath hard after we are finished exercising, what 2 things is the increased oxygen supply doing for the muscle fibers? Resupplying them with ATP and creatine phosphate, as well as to diffuse lactic acid.
Created by: 100006766900221