Brain and the Nervous System Flashcards
1
Q
The brain and spinal cord are protected by the _______ and ____
A
Meninges and Bone
2
Q
What are the 3 meningeal layers?
A
Dura Mater, Arachnoid Mater, Pia Mater
3
Q
Describe the Dura Mater?
A
A strong outer fibrous membrane that adheres to the skull and vertebrae
4
Q
Describe the Arachnoid Mater?
A
The middle interposed membrane between the Dura and Pia
5
Q
Describe the Pia Mater?
A
Inner thin membrane that adheres to the surface of the brain and spinal cord
6
Q
Between the Pia and Arachnoid Maters is called the _____________
A
Sub-Arachnoid space
7
Q
What is found in the sub-arachnoid space?
A
CSF - a watery fluid that nourishes and cushions the nervous system
8
Q
The PNS is made up of all the nerves _______ the CNS
A
Outside
9
Q
A group of nerve cell bodies in the PNS is called a _______
A
Ganglion
10
Q
How many cranial nerves are there?
A
12 pairs
11
Q
How many spinal nerves are there?
A
31 pairs
12
Q
Nerves can be divided into the _______ or sensory pathways and the _______ or motor pathways
A
Afferent - Sensory
Efferent - Motor
13
Q
How many cervical nerves are there?
A
8 pairs
14
Q
How many thoracic nerves are there?
A
12 pairs
15
Q
How many lumbar nerves are there?
A
5 pairs
16
Q
How many sacral nerves are there?
A
5 pairs
17
Q
How many coccygeal nerves are there?
A
1 pair
18
Q
The brain is divided into 3 parts, what are they?
A
Cerebrum
Cerebellum
Brain Stem
19
Q
The brain requires a rich blood and oxygen supply, how is this need met?
A
There are a large amount of blood vessels in the space between the cerebrum and the skull in the Circle of Willis
20
Q
Shallow grooves in the cerebrum are called ______
A
Sulci
21
Q
The raised regions surrounded by grooves are called _____
A
Gyri
22
Q
Deep grooves in the cerebrum are called _______
A
Fissures
23
Q
What are ventricles?
A
A series of spaces and tunnels within the center of the brain that secrete and house CSF which suspends the brain in the skull
24
Q
The largest part of the brain is the ______ it is made of ____________ which are connected by the ____________
A
Cerebrum
2 Hemispheres
Corpus callosum
25
Nerve tracts ______ at the brain stem which results in ________________________
Cross over
| Left side controls the right, Right side controls the left
26
The cerebral cortex is a thin layer, about _____ thick. It provides _______ and _______ for higher cognitive function. It houses _________ neurons
1.5-4mm thick
Connections and pathways
25 billion
27
The cerebellum is connected to the ________ and is responsible for ________________ and _______
Brain Stem
| Coordination of movement and balance
28
The brain stem consists of the _______, ___ and _____________. It is responsible for ____________ and _______
Midbrain, Pons, Meddulla Oblongata
Basic Function and reflexes
29
What are the 2 main functions of the spinal cord?
- Conduct nerve impulses to and from the brain
| - Process sensory information in a limited manner and perform reflex actions
30
Describe the structure of the spinal cord.
- Outer region is white matter(myelinated)
- The inner H-shaped region is grey matter (un-myelinated)
- A central canal is present which is continuous with the 4th ventricle in the brain
31
What are neuroglial cells?
Supportive cells found in the nervous system
32
What neuroglial cells are found in the CNS?
Astrocytes
Oligodendrocytes
Microglia
Ependymal cells
33
What neuroglial cells are found in the PNS?
Schwann cells
| Satellite cells
34
Briefly describe the structure of a neuron
1 Cell body
Multiple processes on one end that receive impulses are called dendrites
A single process on the other end conducts impulses and is called an axon
Axons end is multiple processes called telodendria
35
Most axons are covered in a fatty sheath called _____. In the CNS axons are myelinated by _________, in the PNS axons are myelinated by ________.
Myelin
Oligodendrocytes
Schwann cells
36
A nerve is composed of the ____________________ joint together by a ______________
Processes of many neurons
| Connective tissue sheath
37
Describe Astrocytes:
- Large star shaped cells
- Most abundant glial cell
- Has numerous processes that attach neurons to capillaries
- The provide nourishment for the neurons
38
Describe Oligodendrocytes:
- Smaller than Astrocytes with fewer processes
| - Myelinate in CNS
39
Describe Microglia:
- Smallest glial cells
| - Resident macrophages
40
Describe Ependymal cells:
- Line the ventricles and brain
| - Involved in the production of CSF
41
There are more than __ types of neurotransmitters. What are some common examples?
```
50 types
Acetylcholine
Adrenaline and Noradrenaline
Glutamate
Serotonin
Dopamine
```
42
Neurotransmitters are synthesised by _______ and stored in small compartments called ______________
Neurons
| Synaptic vesicles
43
When an impulse reaches the axon terminals ____ rushes into the cell and triggers ___________________________
Ca 2+
| Exocytosis and release of neurotransmitters
44
What proteins regulate synaptic vesicle exocytosis?
70 Small GTP binding Rab proteins regulate vesicle transport
| SNARE proteins regulate membrane fusion
45
Describe the embryological development of the Nervous System
1. Thickening of ectoderm becomes known as the neural plate, it appears after the 2nd week
2. Lateral regions of the neural plate begin to grow upwards forming neural folds
3. Folds fuse forming a neural tube by the 4th week
46
Pathologies involving the neural tube occur if the tube has not _____________
Closed properly
47
What pathology occurs when the Cephalic region does not close properly?
Anencephaly
48
What pathology occurs when the Caudal region does not close properly?
Spina Bifida
49
Neural tube defects are the _____ common congenital malformation of the CNS. It follows a _____________ inheritance pattern and is related to deficiencies in __________
Most common
Multi-factorial inheritance
Folic Acid
50
Anecephaly is most common in ______ infants and _____ compatible with life
Female
| Not compatible
51
In anencephaly, the brain initially protrudes through _________________ and is gradually _________ by ____________ and ________________. This results in the brain becoming a _____________ of ______ and _______ tissue
A defect in the cranial vault
Destroyed
Mechanical injury and vascular disruption
Vascularised mass of brain and connective tissue
52
What are the clinical manifestation of anecephaly?
- Infant has no brain
- Lacks soft tissue of the scalp and bone for skull vertex
- Malformation of the base of the brain cavity causing bulging eyes
- Short trunk, broad shoulders and absence of neck
- May extend to the upper region of the spinal cord
53
What are the 3 types of spina bifida?
- Occult spina bifida = failure of fusion in the lower lumbar regions, prevents few clinical features
- Meningocele = protrusion of the meninges
- Meningomyelocele = parts of the spinal cord and meninges protrude
54
In severe cases of meningomyelocele how does the spinal cord present?
Spinal cord presents as a flattened mass of nerve tissue that is continuous with adjacent skin and covered by a fine meninge
55
How do we treat Occult spinabifida?
Usually asymptomatic and requires no treatment
56
How do we treat Meningoceles?
Surgery that excises the sac and closes the spinal dura
57
How do we treat Large Meningoceles?
- Surgery like a small meningocele
- Surgey can result in lower motor function damage
- Often requires lifelong care
58
How do we screen for NTDs (Neural Tube Defects)?
- Amniocentesis aka Amniotic Fluid Test (AFT)
- Test for levels of α-foetoprotein (AFP)
- High levels of AFP are ussually diagnostic
- Can be detected on ultrasound by 20 weeks
59
What is Hydrocephalus?
The dilation of the cerebral ventricles that is ussually caused by an obstruction in CSF circulation
Causes compression atrophy of the brain
60
Explain how CSF is produced and circulated:
- 600-700mml produced every day in the lateral ventricles by the Choroid plexus
- Enters the 3rd ventricle then the 4th via the cerebral aqueduct where it exits into the SAS
- CSF is absorbed into the venous circulation in the sinuses of the dura
61
What are the 2 types of Hydrocephalus and what causes them?
Congenital - caused by ventircle malformation, causes enlargement of head
Aqquired - caused by blockage of the 4th ventricle ussualy due to fibrous adhesion or tumours
62
How do we treat Hydrocephalus?
- Insertion of a shunt that diverts flow away from the blockage
- Catheter end is inserted usually into a ventricle and other end usually goes to the peritoneal/abdominal cavity for drainage and reabsorption
63
What are shunts?
Sturdy and flexible plastic tube that consists of a shunt, catheter and valve
64
Voluntary muscle action is controlled by 2 systems; the _________ system controls voluntary motor function, the _________ system controls balance, posture and coordination.
Pyramidal
| Extrapyramidal
65
The axons of the Pyramidal system travel through fiber tracts called _______ or __________ tracts
Pyramidal
| Corticospinal tracts
66
The neurons in Extrapyramidal system have connections with the _______ and ________
Cerebellum
| Basal Ganglia
67
Both pyramidal and extrapyramidal systems are under _______ control and produce ____________________________.
Cortical control
| Smooth, integrated function of muscle
68
A muscle is considered paralysed when it is __________________________________
No longer subject to voluntary control
69
What causes flaccid paralysis?
Diseases of the lower motor neurons
70
What causes spastic paralysis?
Diseases of the cortical motor neurons
71
What happens during flaccid paralysis?
- Lower motor neurons are destroyed or interrupted (e.g. Poliomyelitis)
- Reflex arcs needed for muscle tone are lost
- Muscle goes limp and atrophies
72
What happens during spastic paralysis?
- Cortical neurons are lost (Stroke,Cerebral Palsy) and voluntary control is lost
- Muscle tone is maintained so there is no atrophy
73
Stroke is defined as an injury the the brain tissue resulting from a ____________________. The most common type is called an ________ and acounts for __% of cases
Disturbance in blood supply
Ischemic Stroke
80%
74
What is an aneurysm?
Localised bulging of the wall of an artery due to weakening of the wall over time
75
Describe the characteristics of an Ischemic Stroke:
- Caused by a blood clot or blockage of arteries
- Lack of blood flow and oxygen causes necrosis and degeneration of brain tissue (Infarction)
- Blockages may be caused by thrombosis, arteriosclerosis or an embolism
76
Thrombotic strokes are caused by __________. They ____ blood flow to the brain and provide an area on which ________ can form
Sclerotic Plaques
Slow
Blood clots can form
77
Embolic strokes are caused by ____________ that have formed in __________________ and have blocked blood supply to the brain
Blood clots/thrombi
| In another part of the body
78
Describe the characteristics of a Haemorrhagic Stroke:
- Occurs when a blood vessel supplying the brain ruptures
- Rupture prevents oxygen and nutrients from reaching the brain
- Common in patients with hypertension
- Very severe, often fatal
79
Manifestations of a stroke depend on the _____________________ and the _____________________
Location of the brain damage
| Degree of the tissue damage
80
Strokes generally result in:
- Extensive brain injury
- Paralysis due to upper motor neuron damage
- Sensory disturbances
- Speech problems
- Hemiplegia
81
What is Hemiplegia?
A stroke involving one cerebral hemisphere often leads to weakness and paralysis down the opposite side
82
What are the risk factors for stroke?
Uncontrollable: Controllable:
- Age - Hypertension (Biggest risk)
- History of stroke - Smoking/Drugs/Alcohol
- Race - Obesity
- Heredity - Carotid Artery Disease
- High cholesterol
83
What are the signs and symptoms of stroke?
- 50% of cases are asymptomatic
- Sudden numbness
- Confusion or trouble speaking or understanding speech
- Loss of vision
- Dizziness and loss of balance
84
How do we treat strokes?
Treatment depends on cause, it is important that CT, MRI and Angiograms are done to determine cause ASAP
85
How do we treat Thrombotic Strokes?
- Clot dissolving drugs like TPA (Tissue plasminogen activator) lessen the severity of the stroke by restoring blood flow
- Endartectomy to remove a partially blocked area or implantation of a stent to widen the lumen
86
How can we prevent stroke?
- Control blood pressure
- Stop smoking
- Exercise
- Balanced diet
- Reduce alcohol consumption
- Control diabetes
- Take asprin, omega 3 and vitamin E
87
What is a Transient Ischemic attack (TIA)?
A "mini stroke" caused by a temporary interference with blood supply to the brain due to low BP, decreased heart function and over-medicating of hypertension
88
What are the symptoms of TIAs?
- Light-headedness
- Numbness
- Loss of balance
- Fleeting blindness
- Trouble swallowing or speaking
89
How are TIAs treated?
- Use of anti-platelet agents, mainly aspirin
| - Some incidences require a carotid endartectomy
90
Aneurysms most commonly occur in the _____________ at the base of the bain and the _____
Circle of Willis
| Aorta
91
What are the 3 types of aneurysms?
Saccular - resembles a small sack
Fusiform - spindle shaped
Berry - berry-like in appearance
92
What is the difference between a True and False (psuedoaneurysm) Aneurysm?
True aneurysms involve out pouching of all layers of the arterial wall, may be due to infection, hypertension or be congenital
False/Pseudoaneurysm involve out pouching only of the adventitia, may be caused by trauma involving the intima
93
The most common type of aneurysm is a ______________________, it results from a _______ defect in the muscular and elastic tissue and is found particularly around the ________. It is associated with _______________
Congenital Cerebral Aneurysm (CCA)
Congenital defect
Circle of Willis
Polycystic Kidney Disease
94
How are aneurysms located?
Via an angiogram
95
How do we treat aneurysms?
- Fixing a titanium clip around the aneurysms
| - Coil Embolisation is done by filling of the swelling with a coil to prevent blood entering the aneurysm
96
What are the risk factors for developing aneurysms?
- Hypertension
- Diabetes
- Smoking
- Alcoholism
- Insomnia
97
What are the 4 types of infection found in the nervous system?
Meningitis - Infection of the meninges of the brain or spinal cord
Encephalitis - Infection of the brain tissue
Meningoencephalitis - Infection of both the brain and meninges
Myelitis - Infection of the spinal cord
98
What are the manifestations of CNS infections?
Fever
Stiffness of neck
Headache
Alteration of conciousness
99
Meningitis is caused by ______ and ______ infections, with _____ being the most common at 90% of cases
Bacterial or viral
| Viral is most common
100
Bacterial meningitis is caused mainly by either ____________ or ____________. __________ is the only one known to cause epidemics
Pneumococcus
Meningococcus
Meningococcus
101
Meningococcus is a gram-________ bacteria. There are __ types of meningococcus. ___ serous groups are responsible for all cases in humans
Negative
13
5
102
How are meningococci transmitted between patients? How long is the average incubation period?
Through droplets of respiratory or throat secretions
| 4 days
103
Meningococcal may present as ________ or the more severe __________
Meningitis
| Septicaemia
104
How do meningococci infect patients?
1. They enter the blood through the epithelial cells of the nasopharynx
2. They avoid immune clearance due to their polysacchirde capsule
3. Enter the ventricles of the brain and .'. the CSF
4. Bacteria lyse releasing it's cell wall products into the subarachnoid space causing inflammation and purulent exudate to form
105
What are the signs and symptoms of Meningococcal infection?
- Severe headache
- Fever
- Fatigue
- Stiff/painful muscles and joints, especially neck
- Sensitivity to light
- Purple bruise like rash
- Rapid breathing
- Cold hands and feet and shivers
106
How is meningococcal diagnosed?
Lumbar punctures showing purulent CSF
| Sometimes bacteria can be see in microscopic examination of CSF
107
How do we treat meningococcal?
Antibiotics like penicillin, ampicillin, cloramphenicol and ceftriaxone
108
How can we prevent meningococcal?
Polyssachiride vaccinations for the Serous groups A, C, Y and W135
No vaccine for Serous group B
109
A prion is a _____________________ particle and is a type of ________ agent
Proteinaeceous infectious particle
| Infectious
110
Prions are able to convert _______ from ______ conformations to _______ conformations
Proteins
Normal
Abnormal
111
Prions are responsible for ___________________________ and these diseases are fatal and untreatable
Transmissible Sponfigiform Encephalopathies
112
__________________ is the most common human prion disease. It is fatal within ________. The symptoms are caused by _____________ associated with excessive __________
Creutzfeldt-Jakob disease (CJD)
6 months
Progressive neural cell death
Prion build up
113
What are the symptoms of CJD?
- Rapid dementia leading to memory loss, personality changes and hallucinations
- Speech impairment
- Jerky movements
- Seizures
- Loss of balance
114
Explain the histology of CJD:
- Affected individuals brains appear spongy because they have large vacuoles that look like holes
- Neurons degenerate and astrocytes proliferate in response
115
How is CJD transmitted?
- Contact with infected tissues or biological material
- Can be inherited or sporadic
- Cannibalism
116
What is Alzheimer's Disease?
A chronic neurodegenerative disease characterised by progressive cognitive deterioration and behavioral changes
117
What are the symptoms of AD?
- Short term memory loss
- Decreasing cognitive function
- Emotional disturbances
118
Describe the histopathology of AD:
Neurofibillary tangles form:
- Degenerative changes in the neuron microfillaments
- Fibrils become a thickened tangled mess
- Disrupts axonal transport
Amyloid plaques form:
- Masses of broken down filaments form amyloid plaques that are insoluble to microglia
- Scarring occurs due to insolubility
119
What is amyloid?
The general term for protein fragments that the body produces normally
120
___________ levels decrease during AD
Acetylcholine
121
Macroscopically, AD causes atrophy of the __________
Cerebral cortex
122
What causes AD?
- Unknown, but thought to be due to disruption of brain metabolism
- Genetic factors: Autosomal dominant mutations in Presenilin 1 and 2 and Amyloid precursor protein
123
What are the risk factors for developing AD?
- Advancing age
- ApoE epsilon 4 genotype in some populations
- Head injury
- Poor CVS health
- Exposure to heavy metals
124
What reduces to risk of developing AD?
- Intellectual stimulation
- Social interaction
- Physical exercise
- Healthy diet low in saturated fats
125
How do we treat AD?
- No cure
- Medications offer small symptomatic benefit
- Research in medications aimed at reducing β-amyloid accumulation
126
What is multiple sclerosis?
A chronic inflammatory disease that affects the central nervous system characterised by periodic and random focal degeneration of myelin sheath
127
What causes the myelin sheath to break down in MS?
- Immune cells react to the myelin
- Astrocytes attempt to heal the cells but cause glial scarring
- The local ares of scar formation are called multiple sclerotic plaques
128
Constant glial scarring causes _______ of the neurons and _____________________________.
Hardening
| Disrupts the action potential conduction
129
Multiple sclerotic plaques can be seen by using ______
MRI
130
MS appears in people between __ and __ years old. It is more common in _____ than _____
20 - 40 years old
| Women than men
131
What are the signs and symptoms of MS:
The nature of symptoms depend on the region that has been scarred
- Change in sensation
- Visual problems
- Muscle weakness
- Depression
- Coordination and speech difficulties
- Severe fatigue and pain
132
What causes MS?
The precise cause is not really known
- Multi-factorial
- Possibly genetic
- Possibly viral infection
133
T-cells are known to play a key role in the development of _____________. This means that the disease can be classed as ___________.
Multiple Sclerosis
| Autoimmune
134
Explain how T-lymphocytes have a role in the degeneration of myelin
1. T-cells recognise myelin as harmful
2. T-cells release cytokines to attract macrophages, antibodies and cytokines
3. Macrophages, cytokines and antibodies attack and degenerate the myelin
135
What cells attempt to remyelinate fibers affected by MS?
Oligodendrocytes
136
How do we treat MS?
- No cure
- Treatments aim to halt acute attacks and restore function
- Glucocorticoids halt acute attacks
- Interferons IFN-1 a/b regulate the immune system involvement
137
What is Parkinson's disease?
A chronic debilitating disease characterised by excessive muscle contraction
138
What are the symptoms of Parkinsons?
- Muscle Rigidity
- Tremors
- Bradykinesia (slowing of physical movement)
- Akinesia (loss of physical movement in extreme cases)
139
The primary symptoms of Parkinson's disease are caused by insufficient production of ________ which is produced by _______________ found in the ________.
Dopamine
Dopaminergic Neurons
Substantia Nigra
140
What are the secondary symptoms of Parkinson's disease?
High level cognitive function impairment and subtle language problems
141
Parkinson's is both __________ and _________
Chronic and progressive
142
How does Parkinson's disease develop?
1. Progressive loss of Dopaminergic neurons in the substantia nigra
2. The synapse between these neurons and the basal ganglia no longer synapse correctly
3. Decrease in neurons and dopamine
143
What does a decrease in dopamine do?
Increases muscle rigidity
Increases tone
Abnormal involuntary movements
144
What is the cause of Parkinson's?
- Idiopathic
| - Possibly links to genetics, drugs, head trauma
145
How is Parkinson's treated?
- No cure
- Medications relieve symptoms
- L-dopa is a drug that gets converted to dopamine in the dopaminergic neurons
- Dopamine agonists
- Research in stem cell therapy
146
What are the common tumours that occur in the PNS
- Schwannomas, tumour of the schwann cells that can be singular or multiple and benign or malignant
- Neuromas or neurofibromas are solitary benign tumours that are often attached to nerve trunks
147
What is multiple neurofibromatosis?
- Autosomal Dominant trait
- Skin is disfigured by multiple tumours in the cutaneous nerves
- 10-15% become malignant Schwann Sarcomas
- Surgical intervention is required
148
What kind of tumours can occur in the brain?
Primary tumour, less common
| Metastatic tumour from other cancers (i.e. breast and lung cancer)
149
Tumours in the brain can arise from:
Meninges = Meningioma
- Benign tumour of the Arachnoid cells attached to the Dura
Glial cells = Glioma
- Astrocytoma
- Oligodendroglioma
Ventricular lining = Ependymoma
Rarely blood vessels
Lymphomas may occur
150
Primary tumours in the brain ______________ metastasise outside of the nervous system
do not normally
151
Symptoms of brain tumours are dependent on _________________ but are commonly associated with __________
The size and location
| Headaches
152
How do we treat brain tumours?
- Surgical resection
- Chemotherapy
- Radiotherapy
153
What types of tumours affect the spinal cord?
Ependymomas of the thin filament of tissue at the end of the caudal end of the spinal cord (filum terminale)
Multiple Myeloma (Metastatic tumour) is a tumour of the plasma cells in the bone marrow that may extend into the spinal cavity
154
Tumours involving the spine usually result in ___________________
Loss of motor function below the level of injury
155
Peripheral nerve diseases are caused by _________ and vary degrees of ______________. The effects depend largely on the extend of these issues
Demyelination
| Axonal degeneration
156
Peripheral nevre injuries may result from __________, ______ or a ___________. They can also be caused by __________________ of the nerve by a ___________, this is called ____________.
```
Deep lacerations
Fracture
Crushing injury
External compression by a fibrous band/ligament
Nerve entrapment Neuropathy
```
157
What is Carpal Tunnel Syndrome (CTS)?
A medical condition in which the median nerve is compressed at the wrist causing tingling, pain, weakness and coldness in parts of the hand
158
How do we treat CTS?
Surgical resection of the ligament compressing the median nerve
159
What is polyneuritis?
A peripheral nerve disorder characterised by progressive muscle weakness, numbness and tingling. Muscles may show a degree of atrophy.
160
Polyneuritis is caused by ______________, ___________ and __________.
Systemic diseases like diabetes, exposure to heavy metals, alcoholism
161
What is Guillain Barre's syndrome?
An idiopathic form of polyneuritis characterised by widespread, patchy demyelination of nerves with mild inflammatory changes
162
Guillain Barre's syndrome usually occurs after _____________ and is due to an autoimunne reaction to _____. It is associated with progressive _________________ and can also affect ________.
Viral infections (like measels and mumps)
Myelin
Weakness in the leg
Breathing
163
Symptoms of Guillain Barre's syndrome are usually _______ and patients generally ______ in 1 month
Transient
| Recover
164
The affects that HIV has on the nervous system are classifed into 3 groups:
1. Infections directly associated with the virus
2. Infections caused by opportunistic pathogens
3. AIDS-related tumours
165
In addition to infecting T-cells, AIDS can infect ________ that can transport the the virus to the CNS
Monocytes
166
AIDS viral infection in the nervous system may lead to:
CNS:
- Acute viral meningitis
- AIDS related dementia (Similar to Alzheimers)
PNS:
- Peripheral nerve disorders e.g. Polyneuritis
167
Common opportunistic pathogens that affect the nervous system associated with AIDS infection are:
Herpes Virus Infection
CMV
Toxoplasma Gondii
168
AIDS sufferers are predisposed to various _______ neoplasms like ___________ and ________. These may _________ the nervous system. They carry a ____ prognosis.
```
Malignant
Kaposi's sarcoma
Lymphoma
Metastises to
Very poor
```
