COM 1 Histology Flashcards
1
Q
What is the CNS composed of
A
Brain and spinal cord
2
Q
What is the PNS composed of
A
Spinal, cranial and peripheral nerves and ganglia
3
Q
What is the function of the PNS
A
They conduct impulses to and from the CNS.
4
Q
What is the function of glial cells
A
Support protect and assist neurons in various functions
5
Q
What is the role of the nervous system
A
-Regulates internal body conditions
- Maintains essential behavioural
Patterns
6
Q
What does the nervous system develop from
A
Ectoderm
7
Q
What week does the nervous system develop
A
3rd week
8
Q
Explain how the neural plate is formed starting with the notochord
A
The notochord sends signals to the ectoderm , causing it to thicken and form the neural plate
9
Q
How is the neural tube formed starting with the neural plate
A
The neural plate folds upwards and fuses to form the neural tube
10
Q
What is neuronal cell membrane called
A
Neurolemma
11
Q
Name the 3 main parts of a neuron
A
-Cell body
-Dendrites
-Axon
12
Q
What does the cell
Body contain
A
Nucleus and organelles
13
Q
What is the function of dendrites
A
Recieve stimuli from other neurons at synapses
14
Q
What is the function of Axon
A
Conducts nerve impulses
15
Q
Name 4 different neuron classifications
A
-Multipolar neurons
- Bipolar neurons
- Unipolar neurons
- Anaxonic neurons
16
Q
What is the function of sensory afferent neurons
A
Recieve stimuli from receptors
17
Q
What is the functions of motor efferent neurons
A
Send impulses to muscles and glands
18
Q
What is the function of somatic motor nerves
- Are they voluntary or involuntary
A
Control skeletal muscles
- Voluntary
19
Q
What is the function of autonomic motor nerves
- Are they voluntary or involuntary
A
- Control glands , cardiac and smooth muscle
-Involuntary
20
Q
What is the functions of interneurons
A
Connect other neurons forming complex circuits in the CNS
21
Q
In the CNS where are the :
- cell bodies
- Axins
A
- Cell bodies in grey matter
- Axons in white matter
22
Q
In the PNS where are the :
- Cell bodies
- Axons
A
-Cell bodies in ganglia
- Axons in nerves
23
Q
What does the cell body serve as
A
Trophic center, producing most of the cytoplasm
24
Q
Explain the nucleus in the cell body
A
- Large, euchromatic
25
What 2 organels is the cell body rich in
- Polyribosomes and RER
26
Which Organelle is found only in the cell body
- Golgi apparatus
27
What is the structure of dendrites
Short branched extensions
28
What do dendrites allow neurons to do
To integrate signals from other neurons
29
Explain the difference between dendrites and axons
- Dendrites become thinner as they branch but axons maintain diameter
30
Dendritic spines change shape based on what
Actin filaments
31
What is dendritic spines essential for
Neural plasticity
32
What is the plasma membrane of an axon called
Axolemma
33
What is the contents of the axon plasma membrane called (cytoplasm)
Axoplasm
34
Where does Axon originate from
Axon hillock
35
Do axons branch more or less than dendrites
Less
36
Where do axons end
Terminal boutons
37
What organelles does the Axoplasm of the axon lack
Ribosomes and RER
38
What is Anterograde transport and what protein does it require
It moves organelles and macromolecules from the cell body to the synaptic terminals
+ KINESIN
39
Explain what retrograde transport + the protein it requires
Moves materials from the terminal back to the cell body
- DYNEIN
40
What type of transport in axon can be used to trace neuronal pathways by injecting makers
Retrograde transport
41
Where are nerve impulses initiated
At the axon hillock
42
Explain what happens when the threshold is met to the channels
Na channels open , causing an influx of Na leading to depolarisation
Then the na channels close and k channels open leading to repolarisation
47
Name the three major structures of the CNS
- Cerebrum
-Cerebellum
-Spinal cord
48
What are the major sutures if the CNS protected by
Meninges
49
Name the glial cells the white matter contain
- contains myelinated axons, oligodendrocytes,astrocytes, and microglia
50
What does grey matter contain
- Neuronal cell bodies, dendrites,astrocytes,microglia,
51
What does grey matter form
The outer cortex in the cerebrum and cerebellum
52
What is Cerebral nuclei
Deep grey matter regions containing clusters of neuron cell bodies
53
What doee the cerebral cortex function in
Functioning in sensory integration and voluntary motor control
54
Describe the structure of the cerebral cortex
- 6 neuronal layers with pyramidal neurons
55
What does anterior horns contain+ function
Large motor neuron cell bodies, that send axons into ventral roots
56
What does posterior Horns contain + function
Contain interneurons that receive sensory input
57
What does the central canal contain
Cerebrospinal fluid
58
What else does the white matter contain other than the 4 other components
Myelinated nerve tracts
59
Meninges are found between what?
CNS and the bone
60
Name the 3 Meniges
-Dura mater
-Arachnoid mater
-Pia mater
61
Explain the structure of Dura mater
Thick, outermost layer
62
What is the name of the 2 layers of Dura mater
Periosteal layer
Meningeal layer
63
What do the 2 layers of Dura mater form
Dural venous sinuses
64
What is the function of the epidural space in Dura mater
It separates dura from bone
65
What type of structure is arachnoid
Spider web like
66
What is the Arachnoid layer composed of
- Outer connective tissue layer
-Trabeculae ( collagen and fibroblasts)
67
What is the function of the subarachnoid space
Protects the CNS from trauma
68
Where does the subdural space form between
Dura and arachnoid
69
What does Arachnoid lack
Capillaries
70
What does the subarachnoid space in the arachnoid contain
CSF
71
What does arachnoid vili absorb
CSF
72
What is the name of the 3 layers that the CEREBELLAR CORTEX is organised into
-Moleculer layer
-Purkinje layer
-Granular layer
73
What does the molecular layer of the cerebellar cortex contain
- Neuropil + scattered neuron cell bodies
74
What does the purkinje cell layer of the cerebellar cortex contain
Large Purkinje neurons
75
Where are Ependymal cells located
The line the ventricles of the brain and central canal of the spinal cord
76
What is the shape of Ependyman cells
They have a columnar or cuboidal shape
77
Give examples of ependymal cells
Microvilli
78
What is the function of Ependymal cells
Help circulate and absorb CSF
79
What is the structure of microglia
Small cells with many branches processed
80
What are the functions of microglia
- Phagocytosis
- Immune defense of the CNS
- They secrete cytokines to regulate immune response
81
Where do microglia originate from
Blood monocytes
82
What happens in Multiple sclerosis
The mylein sheaths are damaged by an autoimmune attack
83
Name 2 structures that contribute to multiple sclerosis and how
- Microglia and T cells degrade myelin , impairing neuron function
84
What organelle is affected during multiple sclerosis
Damage exceeds the repair capacity of oligodendrocytes
85
What is another name Schwann cells are given
Neurolemmocytes
86
Where do Schwann cells originate from
Neural crest cells
87
What is the function of Schwann cells
- Form myelin sheaths around PNS axons
- Provide tropic support for axons
88
What is the difference between Schwann cells and oligodendrocytes
One Schwann cell myelinates one axon whereas one oligodendrocyte myelinates many axons
89
What do satellite cells originate from
Neural crest cells
90
Where are satellite cells found
Found around neuronal cell bodies in ganglia
91
What is the function of satellite cells
They provide support , insulation
- They maintain microenvironment
92
What does the granular layer of the cerebellar cortex contain
-small densely packed neurons
93
What is a synapse
Junction between neurons
94
What is the function of synapses
- They convert electrical signals into chemical signals using neurotransmiiters
95
Name the 3 components of a synapse
- Presynaptic Axon terminal
- Synaptic cleft
-Postsynaptic membrane
96
What does the presynaptic axon terminal contain
- Mitochondria and synaptic vesicles
97
How are neurotransmitters released from the synaptic vesicle
- By exocytosis when Ca2+ enters the terminal
98
What does the postsynaptic membrane contain
- Contains receptors for neurotransmitters
99
Name the 2 types of postsynaotic effects
- Excitatory synapse
- Inhibitory synapse
100
Explain what happens in an excitatory synapse
-Na channels opne , allowing sodium to enter
- Causes depolarization, which may trigger an action potential
101
Explain what happens in Inhibitroy synapse
- Cl- channels open, making inside more negative
-Causing hyperpolarization, reducing the chaances of an action potential
102
What does the sum of excitatory and inhibitroy inputs determine
- Whether the neuron fires
103
Explain how neurotransmitters are removed
- Broken down by enzymes
-Then reabsorbed by presynaptic neurons during endocytosis
- Or cleared by glial cells
104
Name 2 amino acids used as neurotransmitters + their effect
- Glutamate ( Excitatory)
-GABA (Inhibtory)
105
What do Glial cells originate from
- Neural plate progenitor cells
106
In the CNS what does glial cells surround
- Neuronal cell bodies and axons + dendrites
107
What do glial cells act like in the CNS and why
- Act like Connective tissue as the CNS has little connective tissue
108
What is neuropil
- Dense network of neuron and glial cell processes in the CNS
109
How do neurpil appear under the microscope
- Fibrous
110
Name the 6 main types of glial cells
- Oligodendrocytes
-Astrocytes
-Microglia
-Ependymal cells
-Schwann cells
-Satellite cells
111
Name the 4 types of glial cells found in the CNS
-Oligodendrocytes
-Astrocytes
-Microglia
-Ependymal cells
112
Name 2 types of Glial cells found in the PNS
- Schwann cells
- Satellite cells
113
What do oligodendrocytes form
- Form Myelin sheaths around CNS axon
114
What is the main type of glial cell in white matter
- Oligodendorcytes
115
How do oligodendrocytes appear under the microscope
They appear as small cells with dark nuclei and clear cytoplasm
116
What is the most numerous and diverse glial cell in the brain
- Astrocytes
117
What is the structure of astrocytes
- Star shaped with long branching processes
118
What do astrocytes contain
- GFAP( Glial fibrillary acidic protein)
119
What do astrocytes originate from
- Neural tube progenitors
120
Name the 2 types of Astrocytes
- Fibrous Astrocytes
-Protoplasmic Astrocytes
121
Where are Fibrous astrocytes found + their structure
- Found in white matter
- Long processes
122
What is the structure of Protoplasmic Astrocytes + where are they found
- Shorter, bushy processes
- Found in grey matter
122
What are the functions of astrocytes
- Cover and modulate synapses
-Regulate ionic balance
-Form blood-brain barrier via perivascular feet
-Fill in injuries
122
What is Alzheimers disease caused by
- Neurofibrillary tangles and B-amyloid plaques
123
What does Alzheimers affect
- Neuornal cell bodies and synapses in the cerebrum
124
What are astrocytomas
- Brain tumours
125
What are astrocytomas derived from
- Astrocytes
126
How are astrocytomas diagnoise
- By identifying GFAP expression
127
What are the functions of blood brain barrier(BBB)
-Protects CNS from toxins,infectious agents and foreign substances
-Maintains the ionic balance needed for neuron function
128
Name areas where the blood brain barrier is absent
- Hypothalamus
-Posterior Pituitary
-Choroid pleuxus
129
What is the functions of choroid plexus
- Produces CSF by removing water from blood
130
Where is the Choroid plexus found in
- Roofs of the third and fourth ventricle
- Parts of lateral ventricular walls
131
What is the choroid plexus made out of
- Vascularized pia mater and cuboidal ependymal cells
132
What does the CSF contain
- Na, K + Cl-, few proteins and sparse lymphocytes
133
What are the symptoms of Parkinsons disease
- Tremors, loss of balance
134
What is the causes of Parkinsosn disease
Caused by gradual apoptosis of dopamine producing neurons in the substantia nigra
135
How is parkinson disease treated
- A dopamine percursor is used to compoenstae for low dopamine levels
136
What is the function of local anesthetics
- Block voltage gated sodium channesl preventing na influx and inhibiting nerve impulses
137
What are SSRIs treatment for
- Depression and Anxiety disorders
138
How do SSRIs work
They work by blocking the reuptake of serotonin at the presynaptic membranes
- This increases the amount of serotonin available to bind to the postsynaptic receptors
