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37.4 The Peripheral Nervous System
The path of a nerve impulse from an internal organ to the brain and back can be traced.
The human brain has four major lobes.
List at least two diseases of the central nervous system.
Collections of cell bodies outside of the central nervous system are found in the ganglia.
The cranial and spine nerves are part of the PNS.
The nervous system has sensory and motor functions that control the muscles.
Ascending tracts carry sensory information to the brain, while descending tracts carry motor commands to the spinal cord.
Smooth muscle, cardiac muscle, and the glands are controlled by the autonomic nervous system.
The sympathetic and parasympathetic divisions are further divided.
Mixed nerves have both sensory and motor fibers.
The head, neck, and facial regions of the body have cranial nerves.
Most of the internal organs have branches to the vagus nerve.
There is a cross section of the spine.
There are two parts to the spine, a dorsal root and a ventral root.
Humans have 31 pairs of spine nerves, which emerge from the spine via two short branches.
The axons of sensory neurons are located in the roots of the spine.
The sensory neuron has a cell body in the dorsal root ganglion.
The axons of motor neurons are located in the ventral roots.
Two roots join to form a nerve.
There are many sensory and motor fibers in the spine.
Nerve impulses travel in sensory axons to the spine from a sharp pin.
Data from sensory neurons is integrated with signals from axons.
Motor axons carry nerve impulses from the spine to the muscles.
The movement of the hand away from the pin is a response to the stimuli.
The PNS has two divisions.
The skin, joints, and muscles are served by the nerves.
Carry motor commands away from the central nervous system to the muscles of the body.
The voluntary control of muscles starts in the brain.
The spinal cord is the only part of the body that can be involved in voluntary responses to stimuli.
The body can respond quickly to stimuli that could disrupt the equilibrium.
Flying objects cause our eyes to blink, and sharp pins cause our hands to jerk, even if we don't have to think about it.
Figure 37.13 shows the path of a reflex that only involves the spine.
If you touch a pin with your hand, it will cause nerve impulses to travel along sensory axons towards the spine.
The gray matter of the spinal cord is home to many interneurons.
Some interneurons have connections with motor neurons.
The short dendrites and the cell bodies of motor neurons are in the spine.
You withdraw your hand from the pin when a muscle contracts.
The effector may be a part of the body.
You can either look at the pin, cry out in pain, or both.
The brain makes you aware of the situation.
You don't feel pain until the brain interprets the information.
If you receive visual information from a cranial nerve, you may know that your finger is bleeding.
You might look for a bandage after that.
The activity of cardiac and smooth muscle is regulated by the PNS.
Without our intent, it carries out its duties.
The sympathetic and parasympathetic divisions are in the system.
Both of these divisions use two neurons and one ganglion for each impulse and innervate all internal organs.
The first neuron has a cell body in the central nervous system.
The second neuron has a cell body and a postganglionic fiber.
The maintenance of homeostasis depends on the actions that regulate blood pressure and breathing rate.
The sensory neurons in contact with internal organs send information to the central nervous system.
They are done by motor neurons.
The preganglionic fiber is short and the postganglionic fiber is long in this division.
The sympathetic division is important during emergency situations.
The sympathetic division dilates the bronchi.
If you are under attack, digestion is not an immediate necessity because of the sympathetic division.
The postganglionic axon releases a neurotransmitter called NE.
adrenaline is a hormones that increases heart rate and contraction.
Each system has different effects.
This division is referred to as the craniosacral portion of the autonomic system.
The preganglionic fiber is long and the postganglionic fiber is short in the parasympathetic division.
The parasympathetic division promotes all the internal responses we associate with a relaxed state; for example, it causes the eye to contract and slows the heartbeat.
The parasympathetic division uses the neurotransmitter acetylcholine.
The peripheral nerves can be affected by several disorders.
Demyelination of peripheral nerve axons occurs when antibodies formed against these microbes cross-react.
Weakness in the legs is the first symptom of GBS.
The respiratory muscles may be weakened if the arms are affected.
The inflammation usually goes away in a few weeks, and most patients recover in 6 to 12 months.
In myasthenia gravis, the abnormal antibodies react with the ACh receptor at the neuromuscular junction of the skeletal muscles.
When an action potential arrives at the synaptic cleft of a peripheral nerve, these antibodies block the normal action of ACh, resulting in muscle weakness.
Although there is no cure, there are drugs that patients respond well to.
Review the neurological explanation for the observation that after you touch a hot stove, you take your hand off the stove.
The study shows an increase in the complexity of the nervous system.
There is a brain and a ganglion present in Annelids.
The resting potential is maintained by the pump.
The action potential travels along the fiber when the axon is conducting a nerve impulse.
The movement of Na+ to the inside causes depolarization, while the movement of K+ to the outside causes repolarization.
The chance of an action potential in the next neuron can either be increased or decreased by the binding of neurotransmitters.
The white and gray matter of the spine are composed of myelinated axons.
Language and speech take place in the cerebrum.
Each cerebral hemisphere has a frontal, parietal, occipital, and temporal cortex.
Lower brain centers receive motor commands from the primary motor area in the frontal lobe.
Lower brain centers in communication with sensory neurons give information to the primary somatosensory area.
The areas for vision and hearing are in different parts of the brain.
There are other regions of the brain.
The human nervous system is affected by a number of diseases.
Some remedies do not require the brain to be involved.
A simple reflex uses the same types of cells.
In contrast to the motor portion of the PNS, the motor portion of the autonomic system controls smooth muscle of the internal organs and glands.
Pick the best answer for the question.
The annelids are the most intelligent.
The cerebellum is only seen in mammals.
The action potential begins when the gates open.
Negative outside and positive inside are what the polarity is now.
The release of Na+ at the presynaptic membrane is what allows the transmission of the nerve impulse.
During an action potential, the axon is re-polarized.
A drug stops the release of ACh from presynaptic endings.
The cerebellum is the largest part of the brain.
The hippocampus and amygdala are part of the limbic system.
The nerve impulses are sent to the central nervous system.
There are two divisions in the autonomic system.
They are part of the brain.
Sympathetic nerve stimulation does not cause the release of glycogen.
The fight-or-flight response is activated in individuals with panic disorder.
A man who lost his leg several years ago continues to experience pain that is similar to what it was before.
Dopamine is found in the brain.
Parkinson disease is caused by a lack of this chemical, whereas the abusers of drugs such as nicotine, cocaine, and methamphetamine enjoy an enhancement of their dopamine activity.
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