Which One Of The Following Activities Is Directly Controlled By The Autonomic Nervous System?

Chapter 16. The Nervous Organization

16.4 The Peripheral Nervous System

Learning Objectives

By the end of this section, y'all will be able to:

Describe the arrangement and functions of the sympathetic and parasympathetic nervous systems
Describe the organisation and function of the sensory-somatic nervous system

The peripheral nervous arrangement (PNS) is the connection between the cardinal nervous organisation and the rest of the trunk. The CNS is like the power constitute of the nervous system. It creates the signals that command the functions of the trunk. The PNS is like the wires that become to individual houses. Without those "wires," the signals produced by the CNS could not control the body (and the CNS would not be able to receive sensory information from the body either).

The PNS can exist cleaved down into the autonomic nervous system, which controls actual functions without conscious control, and the sensory-somatic nervous system, which transmits sensory information from the skin, muscles, and sensory organs to the CNS and sends motor commands from the CNS to the muscles.

Autonomic Nervous Organisation

Which of the following statements is false?

The parasympathetic pathway is responsible for resting the trunk, while the sympathetic pathway is responsible for preparing for an emergency.
Most preganglionic neurons in the sympathetic pathway originate in the spinal cord.
Slowing of the heartbeat is a parasympathetic response.
Parasympathetic neurons are responsible for releasing norepinephrine on the target organ, while sympathetic neurons are responsible for releasing acetylcholine.

The autonomic nervous system serves as the relay between the CNS and the internal organs. It controls the lungs, the eye, smooth muscle, and exocrine and endocrine glands. The autonomic nervous system controls these organs largely without conscious command; it can continuously monitor the conditions of these different systems and implement changes every bit needed. Signaling to the target tissue ordinarily involves 2 synapses: a preganglionic neuron (originating in the CNS) synapses to a neuron in a ganglion that, in plow, synapses on the target organ, as illustrated in Effigy xvi.26. At that place are 2 divisions of the autonomic nervous organization that often take opposing effects: the sympathetic nervous system and the parasympathetic nervous system.

Sympathetic Nervous Organisation

The sympathetic nervous system is responsible for the "fight or flight" response that occurs when an brute encounters a dangerous situation. One way to remember this is to think of the surprise a person feels when encountering a snake ("snake" and "sympathetic" both brainstorm with "s"). Examples of functions controlled by the sympathetic nervous organization include an accelerated heart rate and inhibited digestion. These functions help prepare an organism's trunk for the physical strain required to escape a potentially dangerous situation or to fend off a predator.

Figure_35_04_02 — Figure 16.27. The sympathetic and parasympathetic nervous systems often take opposing effects on target organs.

Near preganglionic neurons in the sympathetic nervous organization originate in the spinal string, as illustrated in Figure 16.27. The axons of these neurons release acetylcholine on postganglionic neurons within sympathetic ganglia (the sympathetic ganglia form a chain that extends aslope the spinal cord). The acetylcholine activates the postganglionic neurons. Postganglionic neurons so release norepinephrine onto target organs. Every bit anyone who has ever felt a rush before a big test, voice communication, or athletic event can adjure, the effects of the sympathetic nervous system are quite pervasive. This is both considering i preganglionic neuron synapses on multiple postganglionic neurons, amplifying the upshot of the original synapse, and because the adrenal gland also releases norepinephrine (and the closely related hormone epinephrine) into the blood stream. The physiological effects of this norepinephrine release include dilating the trachea and bronchi (making information technology easier for the brute to breathe), increasing centre rate, and moving blood from the skin to the middle, muscles, and encephalon (and so the animal can think and run). The strength and speed of the sympathetic response helps an organism avoid danger, and scientists have found prove that it may also increase LTP—allowing the animal to remember the dangerous state of affairs and avoid it in the future.

Parasympathetic Nervous System

While the sympathetic nervous system is activated in stressful situations, the parasympathetic nervous system allows an creature to "residue and digest." One mode to recall this is to think that during a restful state of affairs like a picnic, the parasympathetic nervous organisation is in control ("picnic" and "parasympathetic" both start with "p"). Parasympathetic preganglionic neurons have prison cell bodies located in the brainstem and in the sacral (toward the bottom) spinal cord, as shown in Effigy 16.27. The axons of the preganglionic neurons release acetylcholine on the postganglionic neurons, which are mostly located very near the target organs. Most postganglionic neurons release acetylcholine onto target organs, although some release nitric oxide.

The parasympathetic nervous organization resets organ function afterwards the sympathetic nervous organisation is activated (the common adrenaline dump y'all experience after a 'fight-or-flying' effect). Effects of acetylcholine release on target organs include slowing of heart rate, lowered blood pressure, and stimulation of digestion.

Sensory-Somatic Nervous Arrangement

The sensory-somatic nervous system is made up of cranial and spinal nerves and contains both sensory and motor neurons. Sensory neurons transmit sensory information from the skin, skeletal musculus, and sensory organs to the CNS. Motor neurons transmit messages about desired movement from the CNS to the muscles to make them contract. Without its sensory-somatic nervous system, an animal would be unable to process any information well-nigh its environment (what it sees, feels, hears, and and so on) and could not control motor movements. Unlike the autonomic nervous system, which has two synapses between the CNS and the target organ, sensory and motor neurons have simply one synapse—one ending of the neuron is at the organ and the other directly contacts a CNS neuron. Acetylcholine is the principal neurotransmitter released at these synapses.

Humans take 12 cranial nerves, nerves that emerge from or enter the skull (attic), as opposed to the spinal nerves, which emerge from the vertebral cavalcade. Each cranial nerve is accorded a name, which are detailed in Figure 16.28. Some cranial nerves transmit merely sensory information. For example, the olfactory nerve transmits data nigh smells from the nose to the brainstem. Other cranial nerves transmit almost solely motor information. For example, the oculomotor nerve controls the opening and closing of the eyelid and some eye movements. Other cranial fretfulness comprise a mix of sensory and motor fibers. For case, the glossopharyngeal nerve has a role in both taste (sensory) and swallowing (motor).

Figure_35_04_03 — Effigy sixteen.28. The human brain contains 12 cranial nerves that receive sensory input and control motor output for the head and neck.

Spinal nerves transmit sensory and motor data between the spinal string and the rest of the body. Each of the 31 spinal nerves (in humans) contains both sensory and motor axons. The sensory neuron prison cell bodies are grouped in structures called dorsal root ganglia and are shown in Effigy 16.29. Each sensory neuron has one projection—with a sensory receptor ending in skin, muscle, or sensory organs—and another that synapses with a neuron in the dorsal spinal string. Motor neurons accept cell bodies in the ventral gray matter of the spinal cord that project to muscle through the ventral root. These neurons are unremarkably stimulated by interneurons within the spinal string but are sometimes directly stimulated by sensory neurons.

Figure_35_04_04 — Figure 16.29. Spinal nerves comprise both sensory and motor axons. The somas of sensory neurons are located in dorsal root ganglia. The somas of motor neurons are found in the ventral portion of the gray thing of the spinal cord.

Summary

The peripheral nervous organisation contains both the autonomic and sensory-somatic nervous systems. The autonomic nervous organization provides unconscious command over visceral functions and has 2 divisions: the sympathetic and parasympathetic nervous systems. The sympathetic nervous organisation is activated in stressful situations to set the animal for a "fight or flight" response. The parasympathetic nervous system is agile during restful periods. The sensory-somatic nervous arrangement is fabricated of cranial and spinal nerves that transmit sensory information from skin and muscle to the CNS and motor commands from the CNS to the muscles.

Exercises

Which of the following statements is simulated?
1. The parasympathetic pathway is responsible for relaxing the body, while the sympathetic pathway is responsible for preparing for an emergency.
2. About preganglionic neurons in the sympathetic pathway originate in the spinal string.
3. Slowing of the heartbeat is a parasympathetic response.
4. Parasympathetic neurons are responsible for releasing norepinephrine on the target organ, while sympathetic neurons are responsible for releasing acetylcholine.
Activation of the sympathetic nervous organization causes:
1. increased blood flow into the skin
2. a decreased centre rate
3. an increased heart rate
4. increased digestion
Where are parasympathetic preganglionic cell bodies located?
1. cerebellum
2. brainstem
3. dorsal root ganglia
4. peel
________ is released by motor nervus endings onto muscle.
1. Acetylcholine
2. Norepinephrine
3. Dopamine
4. Serotonin
What are the main differences between the sympathetic and parasympathetic branches of the autonomic nervous arrangement?
What are the main functions of the sensory-somatic nervous system?

Answers

D
C
B
A
The sympathetic nervous system prepares the body for "fight or flight," whereas the parasympathetic nervous organisation allows the body to "residuum and digest." Sympathetic neurons release norepinephrine onto target organs; parasympathetic neurons release acetylcholine. Sympathetic neuron cell bodies are located in sympathetic ganglia. Parasympathetic neuron prison cell bodies are located in the brainstem and sacral spinal string. Activation of the sympathetic nervous organisation increases heart rate and blood pressure and decreases digestion and blood flow to the skin. Activation of the parasympathetic nervous system decreases heart charge per unit and blood pressure and increases digestion and blood catamenia to the peel.
The sensory-somatic nervous system transmits sensory information from the pare, muscles, and sensory organs to the CNS. Information technology too sends motor commands from the CNS to the muscles, causing them to contract.

Glossary

acetylcholine: neurotransmitter released by neurons in the key nervous system and peripheral nervous system
autonomic nervous arrangement: part of the peripheral nervous system that controls actual functions
cranial nervus: sensory and/or motor nervus that emanates from the encephalon
norepinephrine: neurotransmitter and hormone released by activation of the sympathetic nervous system
parasympathetic nervous organization: division of autonomic nervous arrangement that regulates visceral functions during rest and digestion
sensory-somatic nervous system: system of sensory and motor fretfulness
spinal nerve: nerve projecting between peel or muscle and spinal cord
sympathetic nervous system: division of autonomic nervous organisation activated during stressful "fight or flight" situations