Pharmacology · chapter 9 · Introduction to the Nervous System
Structure and Function of the Nervous System
The 14 things this section of the textbook says that you are most likely to be asked about — quoted word for word, not retold. Then 6 practice questions with the reasoning.
Key points
Autonomic versus somatic nervous system
Within the PNS, the autonomic nervous system (ANS) controls involuntary processes and regulates vital functions such as heart rate, digestion, respiration, and glandular secretion, while the somatic nervous system (SNS) consists of motor and sensory pathways that are associated with the voluntary movement of skeletal muscles.
What glial cells do
While glial cells are unable to generate action potentials, they play a key role in the development, support, and protection of neurons.
Three parts of a neuron
Structurally, neurons consist of three main components: the cell body (soma), dendrites, and an axon. The cell body contains the nucleus and other essential cellular components.
Dendrites receive, axons send
Dendrites branch out from the cell body, acting as receivers of signals from other neurons. The axon is a long, slender extension that carries electrical impulses away from the cell body toward other neurons or target cells.
Where neurotransmitters are stored and bind
Neurotransmitters, which are chemical messengers, are stored in the axon terminals of presynaptic neurons. These neurotransmitters then bind to receptors on the receiving neuron's dendrites, transmitting the signal across the synapse and allowing the information to be passed on.
How a chemical synapse works
With chemical synapses, when an electrical signal reaches the end of an axon, it triggers the release of one of the chemical messengers (or neurotransmitters) into the chemical synapse, which is the small gap between neurons.
Effect depends on the target cell
However, if the postsynaptic cell is a muscle cell, muscle contraction or relaxation can result. If the postsynaptic cell is a glandular cell, there will be an increase or decrease in secretion.
Sensory, motor and interneurons
Sensory neurons transmit information from sensory organs to the brain, motor neurons carry signals from the brain to muscles and glands, and interneurons facilitate communication between different neurons within the central nervous system.
Cerebellum and brain stem roles
The cerebellum, located below the cerebrum, controls coordination of movement and postural adjustment. The brain stem is composed of the midbrain, pons, and medulla oblongata.
What the limbic system regulates
The limbic system is composed of a thalamus, hypothalamus, hippocampus, and amygdala. These structures regulate various bodily functions (e.g., activity, sensation, emotion, temperature, appetite, endocrine function, and sexual drive).
Spinal nerves connect CNS and PNS
Nerves extend from the spinal cord and spread throughout the body. There are 31 pairs of spinal nerves. Spinal nerves are the conduit for communication between the CNS and the PNS.
Autonomic nervous system controls involuntary responses
The autonomic nervous system regulates involuntary responses by controlling the cardiac muscle and smooth muscle contractions in addition to gland activity.
Fight or flight
The sympathetic nervous system is commonly known as the “fight or flight” system and is activated when the body is under actual or perceived stress to ready the body’s response to a potential threat.
Rest and digest
Activation of the parasympathetic nervous system translates into a series of bodily reactions that are, generally but not always, opposite of the reactions seen in the sympathetic nervous system.
Terms to know
- neurotransmission
- Neurons grouped together are bundles of nerve cells that transmit electrochemical information via a process known as neurotransmission.
- pineal body
- The pineal body is an endocrine gland located between the two cerebral hemispheres.
- peripheral nervous system
- The peripheral nervous system (PNS) delivers signals between the central nervous system (CNS) and the body.
Practice questions
Stuck on select-all-that-apply? How to take them one option at a time.
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Every question here, with the answer
A client is frightened and anxious before emergency surgery. Which findings would the nurse expect from activation of the sympathetic nervous system? Select all that apply.
- Increased heart rate
- Bronchial dilation
- Bladder constriction
- Pupillary dilation
- Increased salivation
Answer: Increased heart rate, Bronchial dilation, Pupillary dilation
Stress activates the sympathetic fight-or-flight system, which raises heart rate and dilates the pupils and bronchi. Increased salivation and bladder constriction are parasympathetic rest-and-digest effects.
A nurse is reviewing expected effects of parasympathetic activation with a student. Which finding should the student identify?
- Slowed heart rate
- Bronchial dilation
- Pupillary dilation
- Glucose release
Answer: Slowed heart rate
Parasympathetic activation slows the heart rate and lowers blood pressure. Pupillary dilation, glucose release and bronchial dilation are sympathetic effects.
A client has a lesion of the cerebellum. Which finding should the nurse anticipate?
- Changes in appetite and body temperature regulation
- Loss of hearing in one ear
- Loss of basic involuntary respiratory control
- Poor coordination of movement and difficulty with posture
Answer: Poor coordination of movement and difficulty with posture
The cerebellum controls coordination of movement and postural adjustment. Involuntary breathing is a brain stem function, and appetite and temperature are regulated by limbic structures.
A client with a brain stem injury is admitted to the intensive care unit. Which assessment is the nurse's priority based on the function of the brain stem?
- Short-term memory
- Fine motor coordination
- Respiratory and cardiovascular status
- Emotional response
Answer: Respiratory and cardiovascular status
The brain stem is responsible for basic involuntary respiratory and cardiovascular functions, so breathing and circulation are the priority. Memory, coordination and emotion are handled by other brain structures.
A nurse is explaining the functions controlled by the autonomic nervous system. Which functions should the nurse include? Select all that apply.
- Respiration
- Voluntary movement of skeletal muscles
- Glandular secretion
- Digestion
- Heart rate
Answer: Respiration, Glandular secretion, Digestion, Heart rate
The autonomic nervous system controls involuntary processes such as heart rate, digestion, respiration and glandular secretion. Voluntary movement of skeletal muscles belongs to the somatic nervous system.
A student asks which part of a neuron receives signals from other neurons. Which answer by the nurse is correct?
- The glial cells
- The axon
- The axon terminals
- The dendrites
Answer: The dendrites
Dendrites branch from the cell body and act as receivers of signals from other neurons. The axon carries impulses away from the cell body, and glial cells support neurons but cannot generate action potentials.
Where every quote comes from
Section 9.2 Structure and Function of the Nervous System of Pharmacology for Nurses by Tina Barbour-Taylor, Leah Mueller (Sabato), Donna Paris, Dorie Weaver, OpenStax, 2024. Read the whole section free at openstax.org.
The textbook is licensed under CC BY-NC-SA 4.0. This page quotes it word for word and adds the headings, the order and the practice questions; references to the book's figures and stray spaces left by its formatting are removed. The page is shared under the same licence. Nothing here is sold.