Lecture 1 Components of Nervous System Flashcards
(171 cards)
1
Q
What are the 3 major functions of the nervous system?
A
Sensory
Integration
Motor
2
Q
What is the sensory function of the nervous system?
A
Monitors internal and external environment through presence of receptors
3
Q
What is the integration function of the nervous system?
A
Interpretation of sensory information (info processing); complex (higher order) functions
4
Q
What is the motor function of the nervous system?
A
Response to information processed through stimulation of effectors
- Muscle contraction
- Glandular secretion
5
Q
What are the 2 types of neural cells found in the nervous system?
A
Neuroglia: for support, regulation and protection of neurons
Neurons: for processing, transfer, and storage of information
6
Q
What types of cells are in the CNS neuroglia (glial cells)?
A
Astrocytes
Oligodendrocytes
Microglia
Ependymal cells
7
Q
What types of cells are in the PNS neuroglia?
A
Schwann cells (neurolemmocytes) Satellite cells
8
Q
What are the functions of the glial cells?
A
- Mechanical support elements of neurons
- Insulation of neurons
- Phagocytic defense mechanisms
- Modify electrical activity in the neuron
- Regulate metabolism in neurons
9
Q
This cell wraps around the nerve cell and supports the cell. They hypertrophy when the cell is injured
A
Astrocytes
10
Q
This cell is interposed between the neuron and the blood vessels
A
Oligodendroglia
11
Q
Small cells which move along inflamed or damaged brain cells, their function is phagocytosis
A
Microglia
12
Q
These cells line the central canal of the spinal column and ventricular cavities; they are ciliated and combine with endothelial cells to form a choroid plexus which secretes CSF
A
Ependymal cells
13
Q
What are the functions of astrocytes?
A
- Create supportive framework for neurons
- Create blood-brain barrier
- Monitor and regulate interstitial fluid surrounding neurons
- Secrete chemicals for embryological neuron formation
- Stimulate the formation of scar tissue secondary to CNS injury
14
Q
What is the function of oligodendrocytes?
A
Create myelin sheath around axons or neurons in the CNS. Myelinated axons transmit impulses faster than unmyelinated axons
15
Q
What are the functions of microglia cells?
A
- Brain macrophages
- Phagocytize cellular wastes and pathogens
16
Q
What are the functions of the ependymal cells?
A
- Line central canal of spinal column and ventricular cavities
- Ciliated and combine with endothelial cells to form the choroid plexus which secretes CSF
17
Q
What are the functions of Schwann cells?
A
- Surround all axons of neurons in the PNS creating a neurilemma around them
- Neurilemma allows for potential regeneration of damaged axons
- Creates myelin sheath around most axons of PNS (only 1 axon per cell)
18
Q
What are the functions of the satellite cell?
A
-Support groups of cell bodies of neurons within ganglia of the PNS
19
Q
Structural unit of nervous system
A
Neuron
20
Q
What does a neuron consist of?
A
- Once cell body
- One axon, carries impulse away from cell body
- Dendrites: extends from cell body, there may be 1 or many
21
Q
What are the functions of a neuron?
A
- Sensory (afferent): receive sensory input
- Motor (efferent): controls effector tissue of muscle or glands
22
Q
What is a multipolar neuron?
A
Multiple dendrites found in motor and interneurons
23
Q
What is a bipolar neuron?
A
One dendrite and 1 axon attached to cell body, rare, found in eye and ear
24
Q
What is a unipolar neuron?
A
One process from the cell body, an axon. It branches to connect to receptors and the brain or spinal cord. a lot of reflex arc activity
25
What is the functional classification of neurons based on?
Type of info and direction of information transmission
26
What do sensory (afferent) neurons do?
- Transmit sensory info from receptors of PNS towards the CNS
- Most sensory neurons are unipolar, a few are bipolar
27
What do motor (efferent) neurons do?
- Transmit motor info from the CNS to effectors (muscles, glands, adipose tissue) in the periphery of the body
- All are multipolar
28
What do association (interneurons) do?
Transmit info between neurons within the CNS; analyze inputs, coordinate outputs
- Are the most common type of neuron (20 billion)
- Are all multipolar
29
The ____ of neurons are bundled together to form ___ in the PNS & ____/____. Most axons are ____ so these structures will be part of what type of matter?
- Axons
- Nerves
- Tracts/pathways
- Myelinated
- White matter
30
The ___ of neurons are clustered together into ___ in the PNS & ___/___ in the CNS. These are ____ structures and will be part of what type of matter?
- Cell bodies
- Ganglia
- Nuclei/centers
- Unmyelinated
- Gray matter
31
Carries impulses away from cell body and vary in length and thickness
Axon
32
Do thicker or thinner axons have faster conduction?
The thicker the axon, the faster the conduction
33
Do myelinated or unmyelinated axons have faster conduction?
Myelin wraps around and insulates the axon, speeding conduction
34
These are unmyelinated segments between Schwann cells and the farther apart they are, the faster the impulse is transmitted
Nodes of Ranvier
35
A continual sheath around the myelin that plays an essential part in peripheral nerve generation
Neurolemma
36
Do the brain and spinal cord have a neurolemma?
No
37
Regions of the nervous system containing groupings of myelinated axons make up what?
White matter
38
Comprised of groups of neuron cell bodies, dendrites, and synapses (connections between neurons)
Gray matter
39
T/F: Every body function is either recognized or controlled by the brain
True
40
What is the largest part of the brain making up 83% of its mass?
Cerebrum
41
What does the cerebrum do?
- Controls higher mental functions including all conscious thoughts and experience, and all intellectual functions
- Processes somatic sensory and motor information
42
The surface (outermost) layer of gray matter of the cerebrum is known as what?
Cerebral cortex
43
Cerebral gray matter is made up of what?
- Cell bodies
| - Found in cerebral cortex and basal nuclei
44
Cerebral white matter is made up of what?
- Fiber tracts (axons)
- Deep to cerebral cortex
- surrounding basal nuclei
45
What are the cerebral features?
- Gyri
- Sulci
- Fissures
46
Elevated ridges winding around the brain
Gyri
47
Small grooves dividing the gyri
Sulci
48
Divides the frontal lobe from the parietal lobe
Central sulcus
49
Deep grooves, generally diving large regions/lobes of the brain
Fissures
50
What does the longitudinal fissure divide?
The 2 cerebral hemispheres
51
What does the Transverse fissure divide?
The cerebrum from the cerebellum
52
What does the sylvian/lateral fissure divide?
The temporal lobe from the frontal and parietal lobes
53
What are the 4 lobes of the cerebrum?
Frontal, parietal, occipital, and temporal
54
This lobe is located deep to the frontal bone of the skull
Frontal lobe
55
The frontal lobe plays an integral role in what functions?
- Motor control
- Emotions
- Decision making/reasoning
- Personality
56
This is involved in controlling language related movement
Left frontal lobe
57
This is involved in non-verbal abilities
Right frontal lobe
58
What are the frontal lobe of the cerebral cortex functions?
- How we know what we are doing within our environment (consciousness)
- How we initiate activity in response to our environment
- Judgments we make about what occurs in our daily activities
- Controls our emotional response
- Assigns meaning to the words we choose
- Involves word associations
- Memory for habits and motor activities
59
What regions make up the frontal lobe?
- Primary motor cortex
- Broca's area
- Orbitofrontal cortex
- Olfactory bulb
60
What is the primary motor cortex?
- Precentral gyrus
| - Cortical area involved with controlling movements of the body
61
What is broca's area?
Controls facial neurons, speech, and language comprehension. Located on left frontal lobe
62
What is broca's aphasia?
Results in the ability to comprehend speech, but the decreased motor ability (or inability) to speak and form words
63
What is the site of frontal lobotomies?
Orbitofrontal cortex
64
What are the desired effects of frontal lobotomies?
- Diminished rage
- Decreased aggression
- Poor emotional responses
65
What are the possible side effects of frontal lobotomies?
- Epilepsy
- Poor emotional response
- Preservation (uncontrolled, repetitive actions, gestures, or words)
66
This is cranial nerve I, responsible for sensation of smell
Olfactory bulb
67
Located deep to the parietal bone of the skull
Parietal lobe
68
Parietal lobe plays a major role in what functions/actions?
- The senses and integration of sensations
| - Spatial awareness and perception or proprioception
69
What are the cortical regions of the parietal lobe?
- Primary Somatosensory cortex (postcentral gryus)
- Somatosensory association cortex
- Primary gustatory cortex
70
What is the primary somatosensory cortex (postcentral gyrus) involved in?
Processing of tactile and proprioceptive information
71
What is the somatosensory association cortex involved in?
- Assists with the integration and interpretation of sensations relative to body position and orientation in space
- May assist with visuo-motor coordination
72
What is the primary gustatory cortex involved in?
-Interpretation of the sensation of taste
73
This is located deep to the occipital bone of the skull
Occipital lobe
74
What is the primary function of the occipital lobe?
Processing, integration, interpretation, ect. of VISION and visual stimuli
75
What are the cortical regions of the occipital lobe?
- Primary visual cortex
| - Visual association area
76
What is the primary visual cortex?
The primary area of the brain responsible for sight-recognition of size, color, light, motion, dimensions, etc.
77
What is the visual association area?
Interprets info acquired through the primary visual cortex
78
This is located on the sides of the brain, deep to the temporal bones of the skull
Temporal lobes
79
Temporal lobes plan an integral in which functions?
Hearing
Organization/Comprehension of language
Information retrieval (memory and memory function)
80
What are the cortical regions of the temporal lobe?
- Primary auditory cortex
- Primary olfactory cortex
- Wernicke's Area
81
What is the primary auditory cortex responsible for?
Hearing
82
What is the primary olfactory cortex?
Interprets the sense of smell once it reaches the cortex via the olfactory bulbs (not visible on the superficial cortex)
83
What is Wernicke's area?
- Language comprehension
| - Located on the left temporal lobe
84
-What is Wernicke's aphasia?
- Language comprehension is inhibited
- Words and sentences are not clearly understood
- Sentence formation may be inhibited or nonsensical
85
What is arcuate fasciculus?
A white matter tract that connects Broca's area and Wernicke's area through the temporal, parietal, and frontal lobes. Allows for coordinated, comprehensible speech
86
Damage to the arcuate fasciculus may result in what?
Conduction aphasia: where auditory comprehension and speech articulation are preserved, but people find it difficult to repeat heard speech
87
What is the second largest part of the brain making up about 10% of its mass?
Cerebellum
88
What does the cerebellum do?
Provides precise timing and appropriate patterns of skeletal muscle contraction to coordinate repetitive body movements and assist learning of complex motor behavior. Adjusts the postural muscles of the body, controls balance and equilibrium. Recognizes and predicts sequences of events
89
Does cerebellar activity occur consciously or subconsciously?
Subconsciously (as does all processing that occurs outside the cerebral cortex)
90
This calculates the best way to perform a movement
Cerebellar cortex
91
What are the functions of the cerebellum?
- Coordinates the activities of groups of muscles
- Controls skeletal muscle to maintain equilibrium
- Controls posture
- Controls unconscious movements
92
What are the types of cerebellar lesions?
- Asynergia (lack of muscle coordination)
- Ataxia (lack of organized movements)
- Hypotonia
- Asthenia (reduced muscle strength)
93
What is the brainstem made up of?
- Medulla
- Nucleus Gracilus and Cuneatus
- Pyramids and olives
94
What is the medulla?
Part of the brain which attaches to the spinal cord. A large extension of the spinal cord that is composed of white mater and the reticular formation
95
What are the pyramids and olives?
Projection tracts that transfer information
96
This is located under cerebrum and cerebellum
Diencephalon
97
What does the diencephalon do?
- Links cerebrum with brainstem
- Integrates sensory info and motor commands
- Cranial nerve II
98
What is the Diencephalon made up of?
- Pineal gland
- Thalamus
- Hypothalamus
99
What is the pineal gland?
-Secretes hormone melatonin
100
What is the thalamus?
Relays and processes sensory info
101
What is the hypothalamus?
- Hormone production
- Emotion
- Autonomic function
102
All sensory that is projected to the cerebral cortex stops at the thalamus first except what?
Smell
103
What does the thalamus do?
- Filters ascending sensory info for primary sensory cortex
- Relays info between basal nuclei and cerebral cortex
- Mediates sensation, some motor activities, cortical arousal (thus learning and memory)
104
This is the captain of the autonomic nervous system and master overseer of homeostasis
Hypothalamus
105
Major endocrine gland, controls all others. Connected to hypothalamus via infundibulum (stalk).
Pituitary gland
106
What is the basal ganglia made up of?
Islands of gray matter deep inside the cerebral cortex. Consists of caudate, lentiform (putamen and globus pallidus) and the amygdaloid body
107
What is the basal ganglia?
Accessory motor system that works in association with other parts of the CNS to control complex patterns of activity (writing, scissors, throwing, suturing)
108
Where does the midbrain lie?
Between the pons and cerebellum
109
What is the midbrain mostly made up of?
white matter
110
This is an integration center between the cerebrum and cerebellum
Red nucleus
111
T/F: the midbrain is also known as the diencephalon
False, mesencephalon
112
What does the midbrain do?
Processes sight, sound, and associated reflexes. Maintains consciousness. Cranial nerve III & IV
113
What are the 2 basic divisions of the midbrain?
Tectum (roof) and tegmental
114
What happens if the substantia nigra (in tegmentum) of the midbrain gets damaged?
Results in less dopamine release and muscle tone increases: muscle rigidity, difficulty initiating movement which leads to Parkinson's
115
What is reticular formation in the midbrain do?
Maintain consciousness
116
Where is the Pons?
Lies above the medulla and is composed of white and grey mater
117
What does the Pons contain?
The pneumotaxic center which controls respiration and the nuclei of CN V-VII
118
What is the most inferior part of the brain, connecting the brain to the spinal cord?
Medulla oblongata
119
What does the medulla oblongata regulate?
Autonomic functions: arousal, heart rate, BP, pace for respiration and digestion
120
Which cranial nerves come off or go into the medulla oblongata?
IX, X, XI, XII
121
What vital centers does the medulla oblongata maintain?
Reflex centers which are extremely vital for survival concerning cardiac, respiratory, and vasomotor functions
122
What 6 main things is the frontal lobe responsible for?
- Movement
- Thinking initiation
- Reasoning (judgment)
- Behavior (emotions)
- Memory
- Speaking
123
What 4 main things is the parietal lobe responsible for?
- Knowing right from left
- Sensation
- Reading
- Understanding special relationships
124
What 2 main things is the occipital lobe responsible for?
- Vision
| - Color blindness
125
What 3 main things is the cerebellum responsible for?
- Balance
- Coordination
- Fine muscle control
126
What 7 main things is the brain stem responsible for?
- Breathing
- BP
- HR
- Swallowing
- Alertness/sleep
- Body temp
- Digestion
127
What 4 main things is the temporal lobe responsible for?
- Understanding language
- Behavior
- Memory
- Hearing
128
What percent of intracranial volume is made up of the blood supply?
5-10% (60-80 mL)
129
What is the circle of willis?
Carotid arteries provide the anterior cerebral circulation.
- Bifurcates into the external and internal carotid arteries
- The internal branch enters the base of the skull
- Arterial supply of the eye via the ophthalmic artery
- Ultimately bifurcates into the anterior and middle cerebral arteries
130
The posterior circulation results from what?
Vertebral artery
131
How does the vertebral artery enter and what does it do cephalad and caudad?
Enters the posterior fossa through the foramen magnum. Cephalad forms the basilar artery just below the pons. Caudad forms the posterior inferior cerebellar artery and also the spinal arteries
132
What are the branches of the basilar artery?
- Anterior inferior cerebellar
- Superior cerebellar
- Posterior cerebral
133
What is the posterior cerebral artery of the basilar artery?
- The terminal branch of the basilar artery
- Receives the posterior communicating artery from the ICA
- Supplies the inferior and medial surfaces of the occipital and temporal lobes
134
What is the anterior cerebral artery?
- Supplies the medial side of the frontal and parietal lobes
| - Left and right anterior cerebral arteries are connected by the anterior communicating artery
135
What is the middle cerebral artery?
- The largest artery
- Runs along the lateral cerebral fissure
- Supplies the lateral surface of the cerebral hemisphere
136
Where does venous blood drain?
Drains into the venous sinuses which lie between the layers of the dura mater and drain into the internal jugular vein
137
T/F: Sinuses are valveless
True so blood can flow back and forth
138
Is pressure within the sinuses positive or negative?
-Negative (air embolism)
139
What does the blood brain barrier allow passage/transport of?
- Small molecules (H2O, O2, CO2)
- Lipophilic molecules (etoh, heroin)
- Passive transport of glucose
- Active transport of amino acids/NT precursors
140
What does the BBB prevent passage of?
- Large molecules (dopamine)
| - Charged (ionized) molecules
141
What does the dura mater consist of?
An outer (endosteal layer) and an inner (meningeal layer). In between the layers is the dural sinus
142
How is the pia mater anchored to the brain?
By astrocytes, wraps brain tightly like saran wrap
143
What separates the cerebrum and cerebellum?
Tentorium cerebelli
144
Where is the subdural space?
Below dura mater and above arachnoid mater
145
Where is the subarachnoid space?
Below arachnoid mater and above pia mater
146
What does the subarachnoid space contain?
- Collagen/elastic fiber network
- Spider web like (arachnoid trabeculae)
- Filled with CSF
147
What are the frequent sites of intracranial bleeding?
-Subdural and subarachnoid spaces
148
What are the ventricles lined by?
Ependymal cells which help to form the choroid plexus
149
There are ___ lateral ventricles in the cerebral hemisphere
Two
150
Where is the third ventricle located?
Diencephalon
151
Where is the fourth ventricle located?
Between the pons and cerebellum
152
This surrounds all exposed surfaces of CNS
CSF
153
What is the purpose of CSF?
Cushion, support and transport. Interchanges with interstitial fluid of brain
154
What permits CSF to be absorbed into venous blood?
Arachnoid villi protrude superiorly into dural sinus
155
This is on each side of the spinal cord and arises from vertebral arteries and extends to the cauda equina
Posterior spinal artery
156
This arises from the vertebral artery, extends to filum terminale
Anterior spinal artery
157
What is the main blood supply to the cord?
Anterior spinal artery
158
What are the vertebrae protecting the spinal cord?
- 8 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal
159
Collection of nerve roots at inferior end of vertebral canal
Cauda equina
160
What are the dorsal roots of the spinal nerves?
Sensory fibers arising from cell bodies in dorsal root ganglia. Always sensory (afferent)
161
What are the ventral roots of the spinal nerves?
Motor fibers arising from the anterior gray column of the spinal cord. Always motor (efferent)
162
The spinal cord contains ___ grey matter and ___ white matter
- Central
| - Peripheral
163
What 2 organs make up the CNS?
Brain and spinal cord
164
What are the 3 main components of the intracranial vault?
- CSF 10-15%
- Brain 80-85%
- Blood 5-10%
165
Occupies the subarachnoid space, providing protective layer of fluid between the brain and the tissue that surrounds it
CSF
166
Where is CSF produced?
By the choroid plexus in the ventricles
167
CSF makes up how much intracranial volume?
About 10%
168
How much CSF is produced in 24 hours?
500 cc
169
How much CSF is in the CNS at any given time?
About 150 mL
170
What increases CSF volume?
- Choroid plexus papilloma
- Hyperthermia
- Decreased serum osmolality
- Increased CSF osmolality
171
What decreases CSF volume?
- Hypothermia
- Increased hydrostatic pressure
- Diamox
- Increased serum osmolality
- Decreased CSF osmolality
