Module 2: The Central Nervous System Flashcards
1
Q
In general, what does the afferent division of the PNS do?
A
Carry sensory information from the periphery to the CNS
2
Q
In general, what does the efferent division do?
A
Sends instructions back to the periphery from the CNS
3
Q
Describe the structure and function of afferent neurons
A
- Found in the PNS
- Peripehral ending has a sensory receptor
4
Q
Describe the structure and function of interneurons
A
- Found only in the CNS
- Make up 99% of neurons
- Are “connector” neurons that lie between afferent and efferent neurons
- Play a role in creating neural circuits for integrating responses to peripheral information
Play a role in higher brain functions
5
Q
Describe the structure and function of efferent neurons
A
- Cell bodies lie within CNS where they receive presynaptic inputs
- The efferent axon lies mainly outside the CNS
6
Q
Describe glial cells
A
- Do not initiate action potentials
- Use chemical signals to communicate with other glial cells and neurons
- Form the connective tissue of the brain
- Modulate some neuronal activities
- Plays a role in learning/memory
- Most numerous cells in CNS
7
Q
What are the 3 meninges?
A
Dura mater, Arachnoid mater, pia mater
8
Q
Describe the dura mater
A
- Outermost membrane
- Tough and durable
- Always in contact with skull bone except where they separate to create the dural sinsuses
9
Q
What is the dural sinuses? What occurs in there?
A
- Space between the dura mater and skull bone. Venous blood from the brain drains into these sinuses to be returned to the heat. Cerebral spinal fluid also sometimes drain into here
10
Q
Describe the arachnoid mater
A
- Middle meninges
- More delicate than dura mater
- Highly vascularized
11
Q
What is the arachnoid granulation villi
A
Projection of the arachnoid mater through the dura and into the dual sinuses that allows transfer of cerebrospinal fluid from subarachnoid space to cross the villi into the blood of the sinuses
12
Q
Describe the pia mater
A
- Intermost membrane
- Highly vascularized
- Tightly adhered to surface of brain and spinal cord
- In some areas, dips into brain to bring blood supply to the ependymal cells lining the ventricles
13
Q
What are the functions of Cerebrospinal fluid (CSF)? Where is it located?
A
- Protects brain by acting as a shock-absorber
- Brain is suspended in it
- Located within the subarachnoid space (between arachnoid and pia mater)
- Aids in transfer of materials between blood and neuronal tissues
- Influences the composition of the brain’s interstitial fluids
- CSF is replaced more than 3x a day
14
Q
The meninges cover and protect only the brain (T/F)?
A
False! They cover the spinal cord too
15
Q
What is grey matter?
A
Neuronal cell bodies, short interneurons, and glial cells
- Also contain a central canal filled with CSF
16
Q
What is a “horn”?
A
Grey matter. Each half of grey matter is separated into regions called ‘horns’
17
Q
What is white matter?
A
Bundles of nerve fibres (axons)
- Each bundle is connected to a specific region of the brain to transmit info from the brain to the periphery/from the periphery to the brain
18
Q
What does “ascending” and “descending” tracts refer to?
A
White matter
19
Q
the __ horn contains cell bodies of efferent motor neurons
A
ventral
20
Q
the __ horn contains cell bodies of autonomic efferent fibers
A
lateral
21
Q
The cell bodies for afferent nerves located outside the spinal cord are called what?
A
Dorsal root ganglia
22
Q
the dorsal root contains __ input
A
afferent
23
Q
the ventral root contains ___ output
A
efferent
24
Q
What are nerve fassicles?
A
Bundles of myelinated/unmyelinated axons in connective tissues and blood vessels
25
How many cervical nerves are there in the spine? Where do they emerge from?
- 8 pairs
- Emerge from neck
26
How many thoracic nerves are there? Where do they emerge from?
- 12 pairs
- Emerge from chest
27
How many lumbar nerves are there? Where do they emerge from?
- 5 pairs
- From abdomen
28
How many sacral nerves are there? Where do they emerge from?
- 5 pairs
- From pelvis
29
How many coccygeal nerves are there? Where do they emerge from?
- 1 pair
- From coccyx (tailbone)
30
What are the two principle functions of the spinal cord?
1. Being the conduit for transmitting information between the brain and the periphery
2. Integrating certain afferent inputs and efferent outputs that bypass the brain itself
31
What are the 5 components to the reflex arc?
- Receptors in skin
- Afferent neuron
- Interneuron
- Efferent neuron
- Effector
32
What is a simple reflex?
Reflexes that are generally integrated in the spinal cord/brainstem
33
What is an acquired reflex?
A reflex processed in higher brain centres
34
What is the oldest and least specialized portion of the brain?
The brainstem
35
What is the newest and most specialized portion of the brain
The cerebrum
36
What structures does the brain stem consist of?
- The midbrain, pons, and medulla oblongota
37
Why is the brainstem so vital in terms of neuronal communication?
All neuronal communication passes through the brainstem. Most neurons have synapses within it and then are moved for further processing. It is the link between the spinal cord and higher brain centres
38
The brain stem assists in/ functions in/controls:
- Hearing
- Eye movement
- Facial sensations
- Taste
- Swallowing
- Movements of face/neck/tongue
- Vegetative functions of cardiovascular, respiratory and digestive functions
- Muscle reflexes involved in posture and equilibrium
- Reticular information
- Sleep
39
The diencephalon consists of what structures?
- Thalamus
- Hypothalamus
- Epithalamus
- Subthalamus
40
Where are the thalamus and hypothalamus located?
-Upper end of brainstem
41
What are the functions of the thalamus and hypothalamus? (4)
- Relays sensory information between brain regions
- Controls many autonomic functions
- Connects the nervous and endocrine system
- Controls emotion in conjunction with limbic system
42
Describe the function and location of the thalamus
- Located deep within the brain
- An integrating centre for sensory input
- Can amplify/increase importance for signals of specific interest
43
Describe the function of the hypothalamus
- An integration center for homeostatic functions
- Link between autonomic nervous system and endocrine system
44
Roles of hypothalamus (8)
- Controls production and secretion of pituitary hormones
- Plays a role in sleep/wake cycle
- Acts as an autonomic nervous system coordinating centre
- Controls uterine contraction and milk ejection
- Controls fluid intake
- Influences urine output and thirst
- Involved in emotion and behaviour
- Controls body temperature
45
Describe the structure of the cerebral cortex
- Composed of grey matter
- Divided into left and right hemispheres
- Consists of 6 layers
46
What are the left and right hemispheres connected by?
The corpus callosum
47
What are the 4 lobes of the cerebral cortex?
- Frontal lobe
- Parietal lobe
- Occipital lobe
- Temporal lobe
48
What is the function and location of the frontal lobe?
- Responsible for voluntary motor activity, speech, and elaboration of thought
- Located at front of head
49
What is the function and location of the parietal lobe?
- Responsible for receiving and processing sensory input
- Located between frontal and occipital lobes
50
What is the function and location of the occipital lobe?
- Responsible for initial processing of vision input
- Located at back of head
51
What is the function and location of the temporal lobe?
- Involved in vision and hearing
- Located on sides of head
52
What is the somatosensory cortex?
- Receives physical sensations
- Somatosensory cortex receives input from sensory information that occurred on opposite side of body
53
Where is the primary motor cortex found?
In the frontal lobes
54
What separates the somatosensory cortex and primary motor cortex?
The central sulcus
55
Describe the function and location of the cerebellum
- Involved in integration of motor control and sensory perception
- Contributes to muscle tone, coordination, and precision of movement
- Located underneath and posterior to the cerebrum
56
What 3 parts make up the cerebellum?
- The vestibulocerebellum
- The cerebrocerebellum
- The spinocerebellum
57
What is the function of the vestibulocerebellum?
Important for balance, spatial orientation, and control of eye movement
58
What is the function of the cerebrocerebellum?
Receives all input form cerebral cortex
important in planning of voluntary movement and evaluation of sensory information
59
What is the function of the spinocerebellum?
Regulates skilled, voluntary movements
Receives proprioceptive input to allow continuous fine-tuning of movement
60
What is the function and location of the basal ganglia?
- Consists of grey matter located within cerebral white matter
- Associated with motor, cognition, emotions and learning
- Connected to many other brain regions
- Linked to hypothalamus and thalamus (can even exert an inhibitory effect on the thalamus)
61
What are the 4 structures of the basal ganglia?
- Caudate nucleus
- Putamen
- Globus palllidus
- Claustrum
62
What motor control related functions does the basal ganglia have?
- Can inhibit muscle tone throughout the body, allowing precise changes
- Can permit purposeful motor activity while suppressing unwanted movements
- Helps monitor and coordinate contractions, like those relating to posture
63
What structures make up the limbic system?
Lobes of the cerebral cortex, basal ganglia, hypothalamus and thalamus
64
What is the function of the limbic system?
Associated with emotions, behaviour, motivation, and learning
65
Describe positive punishment
The addition of something to decrease behaviour
66
Describe negative punishment
The removal of something to decrease behaviour
67
Describe positive reinforcement
The addition of something to increase behaviour
68
Describe negative reinforcement
The removal of something to increase behaviour
69
Describe short term memory
- Available from 30 seconds - multiple days
- Majority of these memories will be forgotten and pushed out of brain to make room for more memories
70
Describe long term memory
- Available for years
- Memories of information/skills that are used often are rapidly accessible
- Less frequently accessed long term memories are slower to recall, but can be accessed more quickly. through sensory connections
71
What role does the hippocampus play in memory
- Involved in short term memory storage
- Important for consolidation and the initial storage of long-term memories
- Important to declarative memories
72
What are declarative memories?
"what" memories
people, places, facts, etc
73
What role does the cerebellum play in memory?
- Important role in procedural memories
- Memories here can be recalled without conscious effort
74
What are procedural memories?
"how to" memories
motor skills
75
What role does the prefrontal cortex play in memory?
Important for the complex reasoning skills associated with working memory
Responsible for the executive functions involving integration of information for planning, juggling priorities, problem solving, and organizing activities
76
What is habituation? How does it affect the neurons involved?
- A decreases responsiveness to repetitive presentations of an indifferent stimulus that neither rewards nor punishes
- Depresses synaptic activity of the neurons involved
77
What is sensitization? How does it affect the neurons involved?
- Increases responsiveness to mild stimuli that occurs following a strong stimuli
- Enhances synaptic activity
