Table of Contents
- 1 What is the relationship between stimulus and nerve impulse?
- 2 Are nociceptors free nerve endings?
- 3 How does the nervous system react to stimuli?
- 4 What are nerve fibers?
- 5 What information does the Nociceptor relay to the brain about stimuli below threshold?
- 6 What happens when a muscle fiber receives a threshold stimulus?
- 7 What is the fast-pain pathway?
What is the relationship between stimulus and nerve impulse?
When a stimulus is strong enough, a nerve impulse is generated in an “all or none” response which means that a stimulus strong enough to generate a nerve impulse has been given. The stimulus triggers chemical and electrical changes in the neuron.
Where are A delta fibers located?
Polymodal C- and A-delta fibers in the joint serve analogous functions to cutaneous nociceptors. The C fiber nociceptors form a diffuse lattice throughout the articular capsule. A-delta fiber free nerve endings are found in IA and periarticular ligaments.
Are nociceptors free nerve endings?
Nociceptors are free (bare) nerve endings found in the skin (Figure 6.2), muscle, joints, bone and viscera. Recently, it was found that nerve endings contain transient receptor potential (TRP) channels that sense and detect damage.
What would happen if a threshold stimulus is applied to a nerve Fibre?
If a stimulus is above a certain threshold, a nerve or muscle fiber will fire. Essentially, there will either be a full response or there will be no response at all for an individual neuron or muscle fiber.
How does the nervous system react to stimuli?
They detect a change in the environment (stimulus). In the nervous system this leads to an electrical impulse being made in response to the stimulus….Receptors.
Sense organ | Stimuli receptors respond to |
---|---|
Tongue | Chemicals (in food and drink, for example) |
Nose | Chemicals (in the air, for example) |
Eye | Light |
What are medullated nerve fibres?
Definitions of medullated nerve fiber. a nerve fiber encased in a sheath of myelin. synonyms: myelinated nerve fiber. type of: nerve fiber, nerve fibre. a threadlike extension of a nerve cell.
What are nerve fibers?
axon, also called nerve fibre, portion of a nerve cell (neuron) that carries nerve impulses away from the cell body. A neuron typically has one axon that connects it with other neurons or with muscle or gland cells. Some axons may be quite long, reaching, for example, from the spinal cord down to a toe.
What type of stimulus are nociceptors sensitive to?
Nociceptors are sensory receptors with a high threshold for activation and are primarily sensitive to tissue trauma or to non-noxious stimuli that would damage tissue if exposure were prolonged. These receptors are the free endings of primary afferent nerve fibers that are distributed throughout the body’s periphery.
What information does the Nociceptor relay to the brain about stimuli below threshold?
The nociceptor does not relay any information to the brain about stimuli below the threshold. This is because stimuli below the threshold do not generate an action potential and thus the neuron is not actively signalling.
Why does the threshold increase when the interval between the stimuli decreases?
Why does the threshold increase when the interval between the stimuli decreases? Some sodium channels have been inactivated and cannot be reopened immediately. a greater-than-threshold depolarization results and sodium permeability into the cell increases to overcome the potassium exiting.
What happens when a muscle fiber receives a threshold stimulus?
when an individual muscle fiber receives a threshold stimulus, it contracts as much as possible. Any weaker stimulus causes no contraction at all. Any greater stimulus causes the same complete contraction.
What is the difference between threshold stimulus and depolarizing stimulus?
-A threshold stimulus will cause the opening of voltage gated sodium ion channels that will cause further depolarizing stimulus. This stimulus will open still more voltage gated sodium ion channels. A threshold stimulus will cause the opening of voltage gated sodium ion channels that will cause further depolarizing stimulus.
What is the fast-pain pathway?
The fast-pain pathways, composed of A delta fibres, also carry the signals that trigger your withdrawal reflex within a few milliseconds when you receive a painful stimulus, such as when you step on a nail. The activation thresholds for the different types of sensory fibres are different too.
What determines the speed at which sensory fibers conduct nerve impulses?
Both of these traits affect the speed at which these axons conduct nerve impulses: the greater the diameter of the fibre, the thicker its myelin sheath, and the faster this fibre will conduct nerve impulses. Using these two criteria, the following types of sensory fibres can be distinguished.