Nerve Tissue & Spinal Cord Flashcards
1
Q
What are the two sectors of the nervous system?
A
- central nervous system
- peripheral nervous system
2
Q
What are the two divisions of the central nervous system?
A
- brain
- spinal cord
3
Q
What are the two division of the peripheral nervous system?
A
- cranial nerves
- spinal nerves
4
Q
What do the cranial nerves and spinal nerves branch off to?
A
- somatic nervous system
- autonomic nervous system
- enteric nervous system
5
Q
What are the two divisions of the autonomic nervous system?
A
- sympathetic division
- parasympathetic division
6
Q
What does the somatic nervous system do for sensory distribution?
A
- sensory: external stimuli
- somatic receptors (touch and pain)
- special senses such as vision and hearing
7
Q
What does the somatic nervous system do for motor distribution?
A
- skeletal muscles
8
Q
What does the autonomic nervous system do for sensory distribution?
A
- internal stimuli (visceral organs)
9
Q
What does the autonomic nervous system do for motor distribution?
A
- visceral organ
10
Q
What does the enteric nervous system do for sensory distribution?
A
- internal stimuli (GI tract)
11
Q
What does the enteric nervous system do for motor distribution?
A
- GI tract
12
Q
What 2 types of cells does nervous tissue consist of?
A
- neurons
- neuroglia
13
Q
What are neurons?
A
- functional unit cells
- “unique functions” of the nervous system (sensation, information processing, control functions)
- communicate via electrical signals and chemical messengers
14
Q
What are neuroglia?
A
- support cells
- nourish and protect neurons
- preserve the physical and biochemical structure of nervous tissue
- smaller but much more abundant than neurons
- CNS and PNS have different types of neuroglia
15
Q
What is the input of a neuron?
A
- dendrites
16
Q
What do dendrites do?
A
- slender processes that branch out from the cell body
17
Q
What is the output of a neuron?
A
- axon
18
Q
What do axons do?
A
- single long process extending out from the cell body
19
Q
What do axon terminals do?
A
- transmit signals to a
neuron/effector
20
Q
What does the cell body of a neuron do?
A
- expanded portion that contains most of the typical cellular “bits”
21
Q
Describe the structural classifications of multipolar neurons?
A
- many dendrites and
one axon - most common
22
Q
Describe the structural classifications of bipolar neurons?
A
- one dendrite and one axon
- special sense organs (eyes and ears)
23
Q
Describe the structural classifications of unipolar neurons?
A
- dendrites and axon are fused
- sensory neurons of the PNS
24
Q
What are sensory (afferent) neurons?
A
- deliver signals from peripheral receptors to the CNS
- primarily unipolar neurons whose cell bodies are located in peripheral sensory
ganglia - ARRIVE
- Bottom - Up (CNS)
- Outside- In (PNS)
25
What are interneurons neurons?
- transmit signals between sensory and motor neurons (distribute sensory information and coordinate motor activity)
- primarily multipolar neurons that are contained entirely within the CNS
- EXIT
- Top - Down (CNS)
- Inside - Out (PNS)
26
What are motor efferent neurons?
- deliver signals from the CNS to effectors (e.g., muscle cells, glands) in the periphery
- primarily multipolar neurons whose cell bodies are located in spinal cord nuclei
27
What does the mnemonic SAME stand for?
- Sensory/Afferent
| - Motor/Efferent
28
What are the parts of CNS neuroglia?
- Astrocytes
- Oligodendrocytes
- Ependymal cells
- Microglia
29
What are the parts of PNS neuroglia?
- Satellite cells
| - Schwann cells
30
What are astrocytes (CNS)?
- guide neuron development
- create a supportive framework
- maintain the blood-brain barrier
- regulate the composition of the interstitial fluid
31
What are oligodendrocytes (CNS)?
- produce the myelin sheaths of (some) CNS neurons
32
What are ependymal cells (CNS)?
- line the canals and ventricles of the CNS
| - produce cerebrospinal fluid (CSF) and assist in its circulation
33
What are microglia (CNS)?
- act as macrophages
| remove cellular debris and pathogens
34
What are satellite cells (PNS)?
- astrocyte of the PNS
- create a supportive framework
- regulate the composition of the interstitial fluid
35
What are the schwann cells?
- oligodendrocyte of the PNS
| - Produce the myelin sheaths of (some) PNS neurons
36
What are the myelin and what are its functions?
- fatty substance that gets wrapped around the
axons of some neurons
- protects/insulates the axon
- increases the conduction speed of the axon
37
What is white matter?
- region of myelinated axons
38
What is grey matter?
- region of unmyelinated axon and/or neural cell bodies
39
What is multiple sclerosis?
- Autoimmune disease that leads to progressive destruction of the myelin sheaths of neurons in
the CNS
- unknown cause
- starts between ages 20-40
40
What is the resting membrane potential?
- -70mV
41
Why is there a different electrical charge between the inside and outside of neural cells?
- difference in the number of positive and negative ions on either side of the cell membrane, with more negative ions being present within the cell (giving a negative value to the membrane potential)
42
In neurons, electrical excitability changes and takes one of two forms. What are the names of these changes?
- GRADED POTENTIALS (dendrites & cell bodies)
| - ACTION POTENTIALS (axons)
43
What are some aspects of graded potentials?
```
- relatively small change in the resting potential that is localized to a small area of
the cell membrane
- can be either excitatory or inhibitory
- variable effect size
- can undergo summation
- diminish in intensity as they travel
```
44
What are some aspects of action potentials?
- relatively large electrical impulse that is generated when the resting potential
reaches a certain threshold (usually ~-55mv)
- always excitatory
- "all or none"
- travel along the length of an axon at a constant intensity
45
Synapses can be either....?
- electrical
| - chemical
46
How do electrical synapses transmit energy when it reaches the synaptic terminal?
- direct transmission
| - via small connecting channels
47
How do chemical synapses transmit energy when it reaches the synaptic terminal?
- indirect transmission
| - vis the release of neurotransmitters
48
Neurotransmitters have variable effects. What are these effects?
- excitatory
| - inhibitory
49
What are excitatory effects?
- produces a graded potential that brings the neuron’s cell membrane CLOSER to threshold
50
What are inhibitory effects?
- produces a graded potential that brings the neuron’s cell membrane FURTHER from threshold
51
Neurons are constantly receive inputs from how many other neurons?
- hundreds/thousands
52
What is summation?
- the process of adding things together
53
How far does the spinal cord extend down the vertebral canal?
- the top begins around the medulla oblongata and the bottom reaches the L1-2 vertebrae
54
What is the point of the caudal (tail) end called?
- the conus medullaris
55
What is the filum terminale?
- a strand
| of fibrous tissue that anchors the spinal cord to the coccyx
56
What are the two regions of the spinal cord where there is an increased diameter?
- cervical enlargement (C4-T1 vertebrae) – gives rise to the spinal nerves that innvervate the upper limbs
- lumbar enlargement (T9-T12 vertebrae) – gives rise to the spinal nerves that
innervate the lower limbs
57
What is the name of the spot in the centre of the grey matter of the spinal cord?
- central canal
| - runs the length of the spinal cord and is filled with cerebrospinal fluid
58
What are the three regions of grey matter?
- posterior (dorsal) horn
- lateral horn
- anterior (ventral) horn)
59
What cell bodies are within the anterior (ventral) horn?
- somatic motor neurons
60
What cell bodies are within the posterior (dorsal) horn?
- interneurons that relay sensory signals up the spinal cord
61
What cell bodies are within the lateral horn?
- autonomic motor neurons that are only present int eh T1-L2 and S2-S4 spinal corn segments
62
What are the regions of white matter?
- posterior columns
- lateral columns
- anterior columns
63
What do each of the columns of white matter contain?
- ascending (sensory) tracts and/or descending (motor) tracts
64
The spinal cord is divided into how many segments?
- 31
- each segment gives
rise to paired spinal nerves
65
How many pairs of cervical spinal nerves are there?
- 8
| - the eighth emerges below C7 vertebrae
66
How many pairs of thoracic spinal nerves are there?
- 12
67
How many pairs of lumbar spinal nerves are there?
- 5
68
How many pairs of sacral spinal nerves are there?
- 5
69
How many pairs of coccygeal spinal nerves are there?
- 1
70
What are the contents of the posterior (dorsal) root of the spinal cord?
- made up of axons of sensory neurons
| - cell bodies are within a posterior (dorsal) root ganglion
71
What is the spinal nerve made up of?
- sensory and motor axons
| - "mixed"
72
What is the anterior (ventral) root made up of?
- axons of motor neurons
| - cell bodies are within the anterior and lateral horns of the spinal cord
73
Where does the spinal nerve emerge in the vertebral column?
- intervertebral foramina
74
Where do C1-C7 spinal nerves emerge?
- exit superior to their corresponding vertebrae
75
Where do the lumbar and thoracic spinal nerves emerge?
- exit inferior to their corresponding vertebrae
76
What is the collection of the nerve roots of the L2-Co1 spinal segments referred to as?
- cauda equina
77
What is cauda equina syndrome?
- Compression of the cauda equina due to a space-occupying lesion in the vertebral canal inferior to the conus medullaris
78
What are some signs and symptoms of cauda equina?
- weakness and/or pain in the lower limbs (usually bilateral)
- “saddle anaesthesia” (numbness in the genitals, buttocks, and inner thighs)
- urinary and/or fecal incontinence
- sexual dysfunction
79
How is cauda equina treated?
- surgical decompression
