Chapter 9 Nervous System
42. How long is the spinal cord?
17 to 18 inches.
44. How many pairs of spinal nerves are present in the human body?
31 pairs.
22. Describe how a nerve impulse is propagated along the length of a neuron through an action potential.
A threshold stimulus causes a localized action potential on the membrane. The rest of the membrane is in the resting condition. The action potential stimulates the next point. This continues point by point, in domino fashion, along the entire length of the neuron, creating a propagated action potential, or nerve impulse.
37. List and explain the functions of the three control centers located in the medulla. a. Cardiac center
Adjusts heart rate and contraction strength
50. What type of nerve fibers make up each of the following? a. Sensory nerves:
Afferent fibers.
25. What is a reflex?
An automatic, involuntary response to some change either inside or outside the body.
3. What is an effector? What are two types of effectors?
An effector causes an effect in response to directions from the nervous system. Types include muscles and glands.
46. What is the difference between ascending tracts and descending tracts of the spinal cord?
Ascending tracts carry sensory impulses from body parts to the brain, and descending tracts carry motor impulses from the brain to muscles and glands.
43. What surrounds the spinal cord?
Bone, meninges, and cerebrospinal fluid.
50. What type of nerve fibers make up each of the following? c. Mixed nerves:
Both afferent and efferent fibers.
27. What makes up the central nervous system?
Brain and spinal cord.
1. What makes up the nervous system?
Brain, spinal cord, nerves, and ganglia.
53. What are the functions of the following two divisions of the autonomic nervous system? b. Parasympathetic:
Brings the body's systems back to the normal state after an emergency.
10. What is the function of an axon?
Carries impulses away from the cell body.
13. What makes up the gray matter in the central nervous system?
Cell bodies and unmyelinated nerve fibers.
8. What are the three basic parts of a neuron?
Cell body, one or more dendrites, a single axon.
20. What is a resting membrane?
Cell membrane of a nonconducting neuron.
4. What are the two main subdivisions of the nervous system?
Central nervous system and peripheral nervous system.
30. What are the four parts of the human brain?
Cerebrum, diencephalon, brain stem, and cerebellum.
49. What is the makeup and function of the autonomic nervous system?
Consists of nerves that connect the CNS to visceral organs. It mediates unconscious (involuntary) activities.
48. What is the makeup and function of the somatic nervous system?
Consists of nerves that go to the skin and muscles. It is involved in conscious (voluntary) activities.
XII - Hypoglossal
Contraction of muscles of the tongue
XI - Accessory
Contraction of trapezius and sternocleidomastoid muscles
26. What are some examples of reflexes that take place in the body?
Coughing, sneezing, reactions to painful stimuli.
28. What bones surround and protect the brain?
Cranium.
2. Describe the following general functions of the nervous system: b. Integrative functions:
Decisions are made based on sensory input.
29. What three layers make up the meninges, starting with the outer layer?
Dura mater, arachnoid, and pia mater.
50. What type of nerve fibers make up each of the following? b. Motor nerves:
Efferent fibers.
39. What are ventricles?
Fluid-filled cavities in the brain.
32. What five lobes make up the cerebral hemisphere?
Frontal lobe, parietal lobe, occipital lobe, temporal lobe, insula.
18. Describe the structure and function of the three types of neurons: a. afferent (sensory) neurons
Have long dendrites and short axons; carry impulses from peripheral sense receptors to the CNS.
18. Describe the structure and function of the three types of neurons: c. Interneurons:
Have short dendrites and either a short or a long axon; form the connecting link between afferent and efferent neurons.
18. Describe the structure and function of the three types of neurons: b. Efferent (motor) neurons:
Have short dendrites and long axons; transmit impulses from the CNS to effector organs, such as muscles and glands.
52. What are some examples of body functions controlled by the autonomic nervous system?
Heart rate, breathing rate, blood pressure, body temperature.
2. Describe the following general functions of the nervous system: a. Sensory functions:
Information is gathered from stimuli and converted into nerve impulses. detect changes that occur in and outside of the body then converts stimuli as an impulse and transmitted into the brain
38. What is the function of the cerebellum?
Mediates subconscious contractions of skeletal muscles for coordination, posture, and balance.
34. What functions are controlled by the cerebral cortex?
Memory, language, reasoning, intelligence, personality.
36. What structures make up the brain stem?
Midbrain, pons, medulla
threshold stimulus
Minimum level of stimulation that is required to start a nerve impulse or muscle contraction; also called liminal stimulus
Mandibular
Motor fibers to muscles of mastication
III - Oculomotor
Movement of eyes and eyelids
12. What makes up the white matter in the central nervous system?
Myelinated nerve fibers.
47. What makes up the peripheral nervous system?
Nerves that branch from the brain and spinal cord.
51. What are the names of the 12 cranial nerves, and what is the function of each?
Olfactory Optic Oculomotor Trochlear Trigeminal Abducens Facial Vestibulocochlear Glossopharyngeal Vagus Accessory Hypoglossal
16. What is the function of oligodendrocytes?
Oligodendrocytes are neuroglial cells that produce the myelin that surrounds axons in the CNS.
basal ganglia
Paired regions of gray matter located within the white matter of the cerebrum
35. What is the function of the following structures making up the diencephalons? c. Epithalamus:
Pineal gland extends from posterior margin; involved in the onset of puberty and regulates rhythmic cycles in the body.
sympathetic division
Prepares the body for stress (fight or flight), stimulates responses that are necessary to meet an emergency, inhibits the visceral activities that can be delayed momentarily.
31. What is the function of the corpus callosum?
Provides a communication pathway between the cerebral hemispheres.
40. What is the function of cerebrospinal fluid?
Provides support and protection for the CNS, helps nourish the CNS, maintains constant ionic conditions for the brain and spinal cord, provides a pathway for removal of waste products
23. What is a synapse?
Region of communication between two neurons.
35. What is the function of the following structures making up the diencephalons? b. Hypothalamus:
Regulates and integrates the autonomic nervous system, regulates emotional responses and behavior, regulates body temperature, regulates food intake, regulates water balance and thirst, regulates endocrine system activity.
37. List and explain the functions of the three control centers located in the medulla. b. Vasomotor center
Regulates blood pressure
37. List and explain the functions of the three control centers located in the medulla. c. Respiratory center
Regulates the rate, rhythm, and depth of breathing
35. What is the function of the following structures making up the diencephalons? a. Thalamus:
Relay station for sensory impulses going to the cerebral cortex.
I - Olfactory
Sense of smell
Maxillary
Sensory fibers from cheek, nose, upper lip, teeth
Ophthalmic
Sensory fibers from cornea, skin of nose, forehead, scalp
X - vagus
Sensory fibers from pharynx, larynx, esophagus, and visceral organs Somatic motor fibers to muscles of pharynx and larynx Autonomic motor fibers to heart, smooth muscles, and glands to alter gastric motility, heart rate, respiration, blood pressure
VII - Facial
Sensory fibers from taste receptors on anterior two thirds of tongue Motor fibers to muscles of facial expression, lacrimal glands, and salivary glands
IX - Glossopharyngeal
Sensory fibers from taste receptors on posterior one third of tongue Motor fibers to muscles used in swallowing and to salivary glands
45. What are the functions of the spinal cord?
Serves as a conduction pathway for impulses going to and from the brain and as a center for spinal reflexes.
14. Describe the appearance of a node of Ranvier.
Short unmyelinated region between two segments of myelin in a myelinated nerve fiber.
54. How is memory affected as the nervous system ages?
Short-term memory is generally affected more than long-term memory.
6. What function is performed by the following subdivisions of the efferent (motor) division? b. Autonomic nervous system:
Supplies motor impulses to cardiac muscle, smooth muscle, and glandular epithelium.
6. What function is performed by the following subdivisions of the efferent (motor) division? a. Somatic nervous system:
Supplies motor impulses to skeletal muscles.
19. What is the function of neuroglia?
Support, nourish, and protect neurons.
7. What are the two subdivisions of the autonomic nervous system?
Sympathetic and parasympathetic.
33. Where is the cerebral cortex located? What makes up the cerebral cortex?
The cerebral cortex is the outermost portion of the cerebrum and is made up of gray matter (neuron cell bodies and unmyelinated fibers).
Cerebrum
The largest and uppermost part of the brain. It controls consciousness, memory, sensations, emotions, and voluntary movements.
2. Describe the following general functions of the nervous system: c. Motor functions:
The nervous system responds to sensory input and integration. sends signal to muscles causing them to react
15. What is the neurilemma, and what is its function?
The neurilemma consists of a layer of Schwann's cells that surrounds a nerve fiber in the peripheral nervous system. It produces myelin that encases axons in the peripheral nervous system and plays a role in the regeneration of nerve fibers.
Axon
The single efferent process of a neuron that carries impulses away from the cell body
41. What is the starting point and ending point of the spinal cord?
The spinal cord extends from the foramen magnum to the level of the first lumbar vertebra.
21. What happens to sodium ions when a neuron receives a stimulus?
They diffuse into the cell.
17. Why can't nerve fibers in the central nervous system regenerate?
They do not have a neurilemma.
refractory period
Time during which an excitable cell cannot respond to a stimulus that is usually adequate to initiate an action potential
5. What is the function of the following subdivisions of the peripheral nervous system? a. Afferent (sensory) division:
Transmits impulses from peripheral organs to the CNS.
5. What is the function of the following subdivisions of the peripheral nervous system? b. Efferent (motor) division:
Transmits impulses from the CNS to peripheral organs to cause an effect or action.
9. What is the function of a dendrite?
Transmits impulses to the cell body.
II - Optic
Vision
24. How is a nerve impulse transmitted across a synapse?
When a nerve impulse reaches the synaptic knob, neurotransmitters are released into the synaptic cleft and react with receptors on the postsynaptic cell membrane.
11. What is a myelin sheath?
White fatty substance that surrounds many nerve fibers.
Neurotransmitters
a chemical substance that is released from axon terminals to stimulate muscle fiber contraction or a impulse in another neuron
Neuron
a nerve cell, including its process
action potential
a nerve impulse; a rapid change in membrane potential that involves depolarization and repolarization
myelin
a white, fatty substance that surrounds many nerve fibers
V - Trigeminal
a. Ophthalmic b. Maxillary c.Mandibular
10. somat/o
body
3. cerebell/o
cerebellum
4. cerebr/o
cerebrum
Decussation
crossing over
VI - Abducens
eye movement
________ 7. The pons functions in body coordination, posture, and balance.
false (cerebellum)
________ 3. A myelin sheath is formed around axons within the CNS by Schwann cells.
false (dendrites)
________ 7. The spinal cord extends from the base of the skull to the fourth lumbar vertebra.
false (first)
________ 5. The central sulcus divides the cerebrum into two hemispheres.
false (longitudinal fissure)
________ 2. Gray matter is made up of myelinated fibers.
false (white)
________ 5. The CNS is made up of cranial nerves and spinal nerves.
false (PNS)
________ 9. Sensory nerves contain only efferent fibers.
false (afferent fibers)
________ 1. An axon transmits impulses toward a neuron cell body.
false (dendrites)
cerebrospinal fluid (CSF)
fluid that fills the subarachnoid space in the brain and spinal cord and in the cerebral ventricles
7. gli/a
glue
5 cephal/o
head
VIII - Vestibulocochlear
hearing and equilibrium
2. gangli-
knot
1. act-
motion
IV - Trochlear
movement of eyes
6. neur/o
nerve
diencephalon
part of the brain between the cerebral hemispheres and the midbrain; includes the thalamus, hypothalamus, and epithalamus
saltatory conduction
process in which a nerve impulse travels along a myelinated nerve fiber by jumping from one node of Ranvier to the next
9. -tion
process of
Cerebellum
second largest part of the brain; located posterior to the pons and medulla oblongata, and involved in the coordination of muscular movements
8. -lemma
sheath, covering
Nodes of Ranvier
short spaces between segments of myelin in a myelinated nerve fiber
Neuroglia
supporting cells of nervous tissue
dendrites
the branching afferent processes of a neuron that receive impulses from other neurons and transmit them to the cell body
central sulcus
the groove or furrow between the frontal and parietal lobes of the cerebrum
neurilemma
the layer of cells that surrounds a nerve fiber in the peripheral nervous system, and in some cases, produces myelin
brain stem
the portion of the brain between the diencephalon and spinal cord that contains the medulla oblongata, pons, and midbrain
somatomotor cortex
the primary motor area of the brain; transmits motor impulses to the body
somatosensory cortex
the primary sensory area of the brain receives sensory impulses from the body
synapse
the region of communication between 2 neurons
8. syn-
together, with
_______ 10. The body has 12 pairs of cranial nerves.
true
_______ 10. The sympathetic division of the autonomic nervous system prepares the body for fight or flight.
true
________ 1. The function of a neuron is to transmit nerve impulses.
true
________ 2. Neuroglia support and protect neurons.
true
________ 3. Myelin is a white fatty substance that surrounds nerve fibers.
true
________ 4. Sneezing is an example of a reflex.
true
________ 4. Synapse is the name of the region of communication between two neurons.
true
________ 6. The cerebral cortex consists of gray matter.
true
________ 6. The hypothalamus functions in the regulation of body temperature.
true
________ 8. The autonomic nervous system supplies motor impulses to visceral organs.
true
________ 8. The peripheral nervous system provides a communication network between the central nervous system (CNS) and the body.
true
________ 9. Nerves that carry both sensory and motor fibers are known as mixed nerves.
true