Chapter 23: the nervous system
Neurons can be multipolar, bipolar, or unipolar. Oligodendrocytes make the myelin around
the axons and thereby ensure fast conduction. Astrocyte do a lot of things, like
phagocytosis, metabolism of neurons, isolate neurons, and water homeostasis. Microglia
are derived from yolk sac.
Cerebrovascular accidents:
- Ischaemia: lack of blood & thus O2. Causes are obstruction by vessel disease or
embolus, reduced perfusion or reduced O2 tension.
Brain circulation: 4 afferent arteries (carotid and vertebral), become 3 x terminal
arteries. Most typical place, middle cerebral, upon hypertension often break. Stroke
in anterior cerebral = effect legs. Cerebral media = effects whole body, also speech if
stroke is on the left side.
Consequence: neuronal damage and death, loss of myelin, death of glial cells, loss of
tissue due to colliquation, influx of granulocytes and cavitation
- Haemorrhage: bleeding in the brain. Abnormal arteries, hypertension and trauma
are reasons for bleeding. Different types: Epidural (trauma, arterial), subdural
(venous), subarachnoid (arterial, sudden loss of consciousness) are all outside the pia
mater. Intraparenchymal is inside the brain tissue, very severe and easy spread.
Infections:
- Meningitis: occur in the meninges. Most often bacterial and then also severe. From
CFS investigate the cell type that is present. Bacterial is neutrophil, viral is
lymphocytes.
- Encephalitis: occur in encephalon. Often viral and very severe, so most often
lymphocytes present. Microglial nodules (cluster) to clear up the neurons that are
infected.
PML = viral infection, most common by patients with immunocompromised (HIV or
MS) often lethal.
Tumors:
Metastases = lung, breast & skin. Most common type of tumors in the brain.
Primary CNS tumors:
- Gliomas= astrocytes, oligodendrogliomas or ependymomas. Not possible to resect
surgically.
- Primitive neuro epithelial tumors = medulloblastoma often by children.
Use morphology and genetics to determine the tumor type.
Can also have tumor in meninges, take up place in brain. Located outside CNS, can be
surgically extracted.
Degenerative disorders:
- Alzheimer’s:
A lot of atrophy. Mostly associated with memory. Amyloid beta plaques outside the cells.
Tau aggregation inside the cell. Amyloid deposit mostly in the outer layer of the brain, the
GM. If AB monomer is formed, become amyloid plaques. Early onset of disease is mostly
autosomal dominant mutations, late onset mostly genetic risk factors (failure clearance).
Neurons can be multipolar, bipolar, or unipolar. Oligodendrocytes make the myelin around
the axons and thereby ensure fast conduction. Astrocyte do a lot of things, like
phagocytosis, metabolism of neurons, isolate neurons, and water homeostasis. Microglia
are derived from yolk sac.
Cerebrovascular accidents:
- Ischaemia: lack of blood & thus O2. Causes are obstruction by vessel disease or
embolus, reduced perfusion or reduced O2 tension.
Brain circulation: 4 afferent arteries (carotid and vertebral), become 3 x terminal
arteries. Most typical place, middle cerebral, upon hypertension often break. Stroke
in anterior cerebral = effect legs. Cerebral media = effects whole body, also speech if
stroke is on the left side.
Consequence: neuronal damage and death, loss of myelin, death of glial cells, loss of
tissue due to colliquation, influx of granulocytes and cavitation
- Haemorrhage: bleeding in the brain. Abnormal arteries, hypertension and trauma
are reasons for bleeding. Different types: Epidural (trauma, arterial), subdural
(venous), subarachnoid (arterial, sudden loss of consciousness) are all outside the pia
mater. Intraparenchymal is inside the brain tissue, very severe and easy spread.
Infections:
- Meningitis: occur in the meninges. Most often bacterial and then also severe. From
CFS investigate the cell type that is present. Bacterial is neutrophil, viral is
lymphocytes.
- Encephalitis: occur in encephalon. Often viral and very severe, so most often
lymphocytes present. Microglial nodules (cluster) to clear up the neurons that are
infected.
PML = viral infection, most common by patients with immunocompromised (HIV or
MS) often lethal.
Tumors:
Metastases = lung, breast & skin. Most common type of tumors in the brain.
Primary CNS tumors:
- Gliomas= astrocytes, oligodendrogliomas or ependymomas. Not possible to resect
surgically.
- Primitive neuro epithelial tumors = medulloblastoma often by children.
Use morphology and genetics to determine the tumor type.
Can also have tumor in meninges, take up place in brain. Located outside CNS, can be
surgically extracted.
Degenerative disorders:
- Alzheimer’s:
A lot of atrophy. Mostly associated with memory. Amyloid beta plaques outside the cells.
Tau aggregation inside the cell. Amyloid deposit mostly in the outer layer of the brain, the
GM. If AB monomer is formed, become amyloid plaques. Early onset of disease is mostly
autosomal dominant mutations, late onset mostly genetic risk factors (failure clearance).
