Nervous System Flashcards
(166 cards)
1
Q
Two organizations of the nervous system
A
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
2
Q
What consists of the CNS?
A
- Brain
- Spinal Cord
3
Q
What consists of the PNS?
A
-all of the nervous tissue outside of the CNS
4
Q
Functions of the NS
A
- Sensory
- Integrative
- Motor
5
Q
Detection and input
A
Sensory
6
Q
Processing/storing/analyzing info
A
Integrative
7
Q
Output
A
Motor
8
Q
What is nervous tissue designed for?
A
Communication
9
Q
Types of cells of NS
A
- Neuroglia
2. Neurons
10
Q
Function of neuroglia
A
Support, Nourish, Protection
11
Q
3 parts of nerve cells
A
- Dendrite
- Cell Body
- Axon
12
Q
Structure, Function, Receptor Sites of Dendrites
A
Structure: multiple/single extensions off cell body
Function: input portion of the neuron
Receptor Sites: contains lots for receiving chemical messages from other cells
13
Q
A.k.as for Cell Body
A
Soma, Perikaryon
14
Q
Structure, Function Of the Soma
A
Structure: contains the nucleus and other organelles
Function: cell proccesses
15
Q
Structure, Function of Axons
A
Structure: a thin cylindrical process off the cell body
Function: output portion of the neuron
16
Q
What is the presynaptic terminal?
A
The end of the axon that divides into many fine processes
A.k.a Axon Terminal
17
Q
What is the synaptic end bulb?
A
The swollen ends of some axon terminals.
18
Q
What is myelin?
A
Multilayered lipid and protein covering that speeds up signal conduction (action potential)
19
Q
What is a stimulus?
A
Any change in the internal/external environment that is strong enough to stimulate an AP
20
Q
What is an action potential?
A
An electrical signal that travels along the cell membrane of a neuron
21
Q
Responding to a stimulus and converting it into an action potential
A
Electrical Excitability
22
Q
3 Structural Classifications of Neurons
A
- Multipolar
- Bipolar
- Unipolar
23
Q
Structurally, what classifies a neuron?
A
Classified according to number of processes extending from the cell body
24
Q
Several dendrites and one axon
A
Multipolar
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One main dendrite and one axon
Bipolar
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Peripheral axon has sensory receptors and the central axon has axon terminals
Unipolar
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Where would you find multipolar neurons?
Brain, Spinal Cord (CNS), and all Motor Neurons
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Where would you find bipolar neurons?
Retina, Ear
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Where would you find unipolar neurons?
All sensory neurons
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3 Functional Classifications of Neurons
1. Sensory Neurons
2. Motor Neurons
3. Interneurons
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A.k.a Sensory Neuron
Afferent Neurons
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A.k.a Motor Neuron
Efferent Neurons
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A.k.a Interneurons
Association Neurons
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Sensory neurons are mostly what structural classification?
Unipolar
35
Where are the sensory receptors for sensory neurons?
Either at dendritic end or just after sensory receptors that are separate cells
36
What happens once a sensory neuron is activated by a stimulus?
The AP forms and propagates along the axon and is carried into the CNS via afferent neurons
37
Must travel together in spinal and cranial nerves
Sensory Neurons
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What structural classification belongs to motor neurons?
Multipolar
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What happens to the AP in motor neurons?
Propagates away from the CNS to effectors via efferent neurons
40
What are effectors?
The cells and organs
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Where are interneurons located?
Primarily in the CNS between the sensory and motor neurons
42
What is the interneuron's role?
Integrate/process information from the sensory neurons. If a motor response is required, specifics of that response is formulated and relevant motor neurons are activated.
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What structural classification are interneurons?
Multipolar
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The site of communication between two neurons (or b/w a neuron and another type of cell)
Synapse
45
2 Types of synapses
1. Electrical
| 2. Chemical
46
Which synapse is faster and not as common?
Electrical
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In electrical synapses, APs conduct directly between _______ through ______.
Plasma membranes of adjacent cells through gap junctions
48
What do electrical synapses allow for?
Synchronization of function
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Neuron sending the signal
Pre-synaptic neuron
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Neuron receiving the signal
Post-synaptic neuron
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The space between the communicating neurons
Synaptic Cleft
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Chemical released by the pre-synaptic neuron to affect the post-synaptic neuron or effector
Neurotransmitter (NT)
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What should you think of when it comes to neurotransmitters?
"Lock and Key" because NT binding receptors are specific to the NT released
54
What happens when the AP reaches the end of the pre-synaptic neuron?
- Neurotransmitter releases
- NT diffuses across the synaptic cleft
- NT binds to post-synaptic cleft
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When is the continuation of the AP more likely?
If NT is excititory
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When is the continuation of the AP less likely?
If NT is inhibitory
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Common Neurotransmitters (4)
1. Acetylcholine (ACh)
2. Gamma-aminobutyric Acid (GABA)
3. Dopamine
4. Serotonin
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PNS/CNS excitatory at neuromuscular junction (NMJ)
Acetylcholine (ACh)
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CNS, inhibitory
Gamma-aminobutyric Acid (GABA)
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Excitatory or inhibitory depending on receptor, emotional response, addictive behaviour, skeletal muscle tone
Dopamine
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Excitatory or inhibitory depending on receptor, sensory perception, temperature regulation, mood, sleep, appetite
Serotonin
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In cases of injury/disease, what does neuroglia do?
Multiplies to fill the spaces formerly occupied by neurons
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Neuroglia in the CNS (4)
1. Astrocytes
2. Oligodendrocytes
3. Microglia
4. Ependymal Cells
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Helps form the blood-brain barrier and provides nutrients to neurons
Astrocytes
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What is the blood-brain barrier? Structural components?
- Specialized barrier that prevents passage of materials from the blood and the brain
- Protects the brain from harmful substances
- Thick basement membrane, tight junctions
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Form/maintain the myelin sheath of CNS neurons
Oligodendrocytes
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Phagocytotic cells that remove debris, phagocytize microbes (immune cells)
Microglia
68
Line cavities of the brain and spinal cord and produce/assist in circulation of cerebrospinal fluid
Ependymal Cells
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What is cerebrospinal fluid (CSF)?
Clear, colourless fluid that circulates around the brain and spinal cord.
Protects the brain and spinal cord from injury
70
Neuroglial cell
Shwann Cells
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How are shwann cells similar to oligodendrocytes?
Like the oligodendrocytes in the CNS forming the myelin sheath, shwann cells encircle axons in myelin sheath in the PNS
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What are shwann cells involved in?
Regeneration of PNS axons
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Structures of the CNS
Brain, Spinal Cord
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Structures of the PNS
- cranial nerves and their branches
- spinal nerves and their branches
- ganglia
- enteric plexuses
- sensory receptors
(everything else)
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What is a nucleus?
A cluster of neuronal cell bodies in the CNS
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What is ganglion?
A cluster of neuronal cell bodies in the PNS
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What is a tract?
A bundle of axons in the CNS
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What do tracts do?
Interconnect neurons in the spinal cord and brain
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What is a nerve?
A bundle of axons in the PNS
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Spinal nerves connect ______
spinal cord to the periphery
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Cranial nerves connect ____
brain to the periphery
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Collections of cell bodies and unmyelinated nerve fibres in the CNS
Grey Matter
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Collection of cell bodies of myelinated axons in the CNS
White Matter
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Describe the Spinal Cord
- encased in the vertebrae
- extends from the bottom part of the brain stem to the 2nd lumbar vertebra (L2)
- at L2, tapers into Conus Medullaris
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The roots of the spinal nerves below the conus medullaris
Cauda Equina
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____ matter surrounds an inner core of ____ matter.
White, Grey
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2 grooves that divide the white matter into right and left sides
- Anterior Median Fissure
| - Posterior Median Sulcus
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What is the central canal?
A small tube in the centre of the spinal cord (SC) that contains CSF
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Each side of grey matter is divided into regions called _____
Horns
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Axons of incoming sensory neurons and interneurons
Posterior Horn (A.k.a Dorsal)
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Motor Nuclei
Anterior Horn (A.k.a Ventral)
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Present in thoracic, upper lumbar, sacral portions, they contain sympathetic nuclei.
Lateral Horn
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Each side of white matter is divided into regions called ____
Columns
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What are the three regions within the columns?
1. Anterior Columns
2. Posterior Columns
3. Lateral Columns
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Anterior Column A.k.a
Ventral
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Posterior Column A.k.a
Dorsal
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What does each column have in common?
Contains tracts that have a common origin or destination
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Sensory Tracts consist of _______________
axons that conduct APs toward the brain
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Sensory Tract A.k.a
Ascending Tract
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Motor Tracks consist of _________________
Axons that conduct APs away from the brain
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Motor Tract A.k.a
Descending
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Parts of the brain (4)
1. Brain Stem
2. Cerebellum
3. Diencephalon
4. Cerebrum
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Continuos of the spinal cord, before the dienceohalon
Brain Stem
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3 Regions of the brain stem (inferior to superior)
1. Medulla Oblongata
2. Pons
3. Midbrain
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What do the regions of the brain stem contain?
1. Nuclei (bundle of cell bodies in CNS)
| 2. Cranial Nerves (bundle of axons in PNS to brain)
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What kind of formation extends through the brainstem?
Net-like reticular
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Contains centres for the control of heart rate, blood pressure, breathing, swallowing, vomiting
Medulla Oblongata
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Contains centres for the control of breathing
Pons
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Contains centres for reflex visual activities (tracking moving objects, scanning stationary objects), and hearing
Midbrain
110
What part of the brain contains the nuclei, Substantia Nigra and what does it do?
Midbrain
| Neurons that make dopamine extend from it
111
What is reticular formation?
A net-like formation of neural tissue that spreads throughout the brainstem containing the reticular activating system
112
What does the reticulating activating system help with?
- consciousness
- maintaining attention
- prevents sensory overload (filters insignificant info)
- regulate muscle tone
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Posterior to the brain stem
Cerebellum
114
What is the cerebellum responsible for?
- smoothes and coordinates skeletal muscle contraction
| - regulates posture and balance
115
What three things does the Diencephalon include?
1. Hypothalamus
2. Thalamus
3. Epithalamus
116
Major regulator of homeostasis
Hypothalamus
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What else is the hypothalamus responsible for?
1. Controls/integrates autonomic NS
2. Hormone production
3. Emotion and behaviour (w/limbic system)
4. Eating and drinking
5. Body temperature
6. Circadian rhythm
118
24 hr cycle in processes of living things
Circadian Rhythm
119
The major relay station for most sensory input to the cerebral cortex
Thalamus
120
Involved in smelling (especially emotional responses to smell)
Epithalamus
121
What gland does the epithalamus contain?
Pineal Gland
122
How is the cerebrum divided?
Two halves, called hemispheres
123
What does the cerebrum consist of?
1. Outer rim of grey matter (cerebral cortex)
2. Inner layer of white matter
3. Grey matter nuclei deep within the white matter
124
Contains:
- sensory areas involved in perception
- motor areas involved in the execution of voluntary movement
Cerebral Cortex (outer rim of grey matter)
125
Contain areas that deal with memory, emotions, reasoning, will, judgment, personality, intelligence
Association Areas (white matter)
126
Basale Ganglia A.k.a
Basal Nuclei
127
Basale Ganglia responsible to help (4)
1. Regulating the starting and stopping movements
2. Control subconscious contraction of skeletal muscles
3. Suppress unwanted movement
4. Set resting muscle tone
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Functionally, what are the basale ganglia linked to?
Substantia Nigra
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Involved in emotion, smelling, and memory
The Limbic System
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What does the limbic system include?
Parts of the hypothalamus, the hippocampus, amygdala, and other nearby structures
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Functions in memory (encoding, consolidation, and retrieval). Short term to long term.
Hippocampus
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Important in emotional function (especially fear)
Amygdala
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Three protective layers of CT that encircle the brain and SC. What are they?
Meninges
1. Dura Matter
2. Arachnoid Membrane
3. Pia Matter
134
Tough outer layer of CT in the CNS
Dura Matter
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Middle layer of CT in the CNS
Arachnoid Membrane
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Inner layer of CT in the CNS
Pia Matter
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The adipose and CT filled space between the wall of the vertebral canal and dura matter
Epidural Space
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Interstitial fluid filled space between the dura mater and arachnoid membrane
Subdural Space
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CSF filled space between arachnoid membrane and the pia matter
Subarachnoid Space
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PNS is all nervous tissue outside the CNS including...
1. Cranial Nerves
2. Spinal Nerves
3. Ganglia
4. Sensory Receptors
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What are cranial nerves? How many pairs do they have?
1. Path of communication between the brain and the periphery
| 2. 12 pairs of nerves that exit from the base of the brain
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What are spinal nerves? How many pairs do we have?
1. Paths of communication between the spinal cord and the periphery
2. 31 pairs
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____ bundles of axons and associated neuroglial cells wrapped in _________
Parallel, several layers of CT
144
What do spinal nerves connect?
Spinal cord to--receptors, muscles, glands
145
How are the 31 spinal nerves numbered?
According to the region and level of the vertebral column from which they emerge
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Not all spinal nerves are aligned to their corresponding vertebrae
Lumbar, sacral, coccyeal nerves descend from L2 to their respective levels
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Two bundles of axons that connect the spinal nerve to the spinal column
Nerve Root
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A bundle of motor axons
Anterior (Ventral) Root
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A bundle of sensory axons
Posterior (Dorsal) Root
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A swelling in the posterior root containing cell bodies of sensory neurons of the PNS
Posterior/Dorsal Ganglion Root
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CT of a Spinal Nerve, Innermost, covers axon
Endoneurium
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CT of a Spinal Nerve, Middle layer, covers fascicles
Perineurium
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Fascicles A.k.a
Bundle of axons
154
CT of a Spinal Nerve, Outermost layer, covers spinal nerve
Epineurium
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Which layers of the CT of a Spinal Nerve is highly vascularized?
Epineurium and Perineurium
156
Subdivisions of the PNS
1. Somatic NS (SNS)
2. Autonomic NS (ANS)
3. Enteric NS (ENS)
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"Voluntary Nervous System"
Somatic NS
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First order neurons A.k.a
Sensory Neurons
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Sensory Neuron and Motor Neuron's responsibility in the SNS
Sensory: convey info to CNS (temp, pain)
Motor: conduct impulses from CNS to skeletal muscles only
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Monitors and controls body activities automatically
Autonomic NS
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2 Divisions of autonomic ns
1. Sympathetic (SyNS)
| 2. Parasympathetic (PaNS)
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Fight or flight, high activity comes from being excited, scared, threatened
Sympathetic NS
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Responses of Sympathetic NS
- Pupil dilation
- Increase HR, BP
- Airway dilation
- Vasodilation of skeletal and cardiac muscle
- Glucose Release
- Vasoconstriction in kidneys and digestive tract
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Rest and Digest, conserve and restore energy systems
Parasympathetic NS
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The balance between sympathetic and parasympathetic activities, regulated by _____.
Autonomic Tone, Hypothalamus
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Sensory neurons that monitor chemical changes within the gastrointestinal tract and stretching its walls
Enteric NS
