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Anatomy Mod 5 Test
Anatomy
Question | Answer |
---|---|
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. |