What is the main function of the nervous system?
Key Terms
What are the defining features of neurons?
These are the functional units of the nervous system. They synapse with other neurons and transmit electrical and chemical signals. A neuron is bro...
What two components does the central nervous system include?
brain spinal cord
Name two main structures of the peripheral nervous system.
spinal nerves cranial nerves In the PNS, neurons are organized into peripheral structures called ganglia.
Related Flashcard Decks
Study Tips
- Press F to enter focus mode for distraction-free studying
- Review cards regularly to improve retention
- Try to recall the answer before flipping the card
- Share this deck with friends to study together
| Term | Definition |
|---|---|
What is the main function of the nervous system? | It controls the body through electrical and chemical signals. Its roles include both sensory and motor functions, as well as the control of basic life processes. The nervous system involves both voluntary and involuntary control. |
What are the defining features of neurons? | These are the functional units of the nervous system. They synapse with other neurons and transmit electrical and chemical signals. A neuron is broadly composed of: Dendrites, or branched structures that receive incoming signals A cell body, which contains the nucleus An axon, or projection along which the signal propagates away from the cell body. |
Name the two divisions of the nervous system. | central nervous system (CNS) peripheral nervous system (PNS) |
What two components does the central nervous system include? | brain spinal cord |
Name two main structures of the peripheral nervous system. | spinal nerves cranial nerves In the PNS, neurons are organized into peripheral structures called ganglia. |
Name the two divisions of the peripheral nervous system. | somatic nervous system autonomic nervous system The somatic system involves the conscious movement of skeletal muscles, while the autonomic system deals with the involuntary functioning of internal organs. |
What is the function of the somatic nervous system? | It is generally associated with voluntary skeletal muscle movement. However, it also includes sensory neurons that transmit signals to the central nervous system. Sensory neurons are afferent, meaning that they carry signals toward the spinal cord. Motor neurons are efferent and travel from the spinal cord to effector muscles. |
Define: sensory neuron | It receives information from a peripheral receptor, then transmits it as an electrical signal to the spinal cord. This information could relate to the external environment or the body’s interior. Sensory neurons are also called afferent neurons. Afferent structures always travel toward the organ or system in question; here, afferent neurons travel toward the spinal cord. |
Define: motor neuron | It transmits an electrical signal from the spinal cord to an effector muscle to initiate movement. Motor neurons are also called efferent neurons. Efferent structures always travel away from the organ or system in question; here, efferent neurons travel away from the spinal cord. |
Define: reflex | It is a quick, involuntary action that is provoked by a specific stimulus. Examples include the knee-jerk reflex and blinking when startled. |
What is a reflex arc, and what components does it include? | It is the set of neurons that promotes a specific reflex. The neurons involved always synapse in the spinal cord. Some reflex arcs are monosynaptic, which include only a sensory and a motor neuron. More complicated reflexes often require polysynaptic arcs, which contain at least one interneuron as well. |
A student in your study group mentions that reflexes cannot occur if signal transmission to and from the brain is blocked. What, if anything, is wrong with this statement? | Reflexes do not require any input from the brain. They are fully unconscious and involve only a sensory neuron, a motor neuron, and one or more synapses in the spinal cord. Avoiding the brain allows the reflex to take place rapidly, which is especially important in dangerous situations. |
What is the function of the autonomic nervous system? | It is involved in the involuntary control of muscles and glands. It can promote a variety of functions including peristalsis, changes in heart rate, vasodilation and vasoconstriction, and more. The ANS includes two main divisions: the sympathetic nervous system and the parasympathetic nervous system. |
Of the following structures, which does not fall mainly under autonomic control? cardiac muscle in the heart smooth muscle in blood vessel walls skeletal muscle in the quadriceps smooth muscle in the small intestine | Skeletal muscle, whether in the quadriceps or elsewhere, is generally controlled by the somatic nervous system. The other choices (smooth muscle and cardiac muscle) are involuntary and would fall under autonomic control. |
Name the two divisions of the autonomic nervous system. | sympathetic nervous system parasympathetic nervous system The sympathetic system is commonly known to activate “fight-or-flight” responses, while the parasympathetic system relates to “resting and digesting.” |
What is the function of the sympathetic nervous system? | It serves to activate certain bodily processes when in cases of stress or danger. It is commonly known as the “fight-or-flight” system. Broadly, the sympathetic system speeds up heart rate, increases blood flow to muscles, and inhibits digestion. |
Name four physiological responses triggered by the sympathetic nervous system. | increases heart rate increases blood flow to skeletal muscle decreases blood flow to the digestive system; inhibits peristalsis dilates pupils |
What is the function of the parasympathetic nervous system? | It serves to activate certain bodily processes when at rest and in safe conditions. It is especially active after eating and is commonly known as the “rest-and-digest” system. Broadly, the parasympathetic system slows down heart rate and increases blood flow to the digestive system. |
Name four physiological responses triggered by the parasympathetic nervous system. | decreases heart rate decreases blood flow to skeletal muscle via vasoconstriction increases blood flow to the digestive system via vasodilation; promotes peristalsis constricts pupils Other effects include the stimulation of sexual arousal, salivation, and urination. |
What is the main neurotransmitter associated with parasympathetic activity? | Acetylcholine is the parasympathetic neurotransmitter at both the preganglionic and postganglionic synapses. Note that the parasympathetic function of acetylcholine is distinct from its role in the promotion of muscle contraction at the neuromuscular junction. |