NEUROCYTOLOGY Flashcards
Neurons and Glial cells derived from the ___________.
Neuroectoderm
Supporting structures of the nervous system derived from the __________.
Mesoderm
The functional unit of the nervous system
Neurons
TRUE/FALSE
Signaling and Trophism are the most important function of the neurons?
TRUE
Other functions:
1. Generates and conducts electrical activity
- Transmits information throughout the N.S.
- Exerts long-term effects required for storage of information
TRUE/FALSE
Normal mature neurons do not proliferate, but they can undergo adaptive changes in response to injury?
TRUE
These supporting cells of Neuroectodermal origin comes from the greek word which means “glue”
Glial cells
This cells mainly glue together or support the neurons to make-up the nervous system
Glial cells
Consists of multiple tightly wrapped layers of plasma membrane that ensheathe large diameter axons.
Myelin
Form myelin sheaths in CNS (spinal cord and brain)
Oligodendrocytes
-In the CNS, processes from a SINGLE oligodendrocyte contribute to the myelin sheath of SEVERAL axons near the cell (1: many)
Form myelin sheaths in PNS (peripheral nerves and cranial nerves)
Schwann cells
-each Schwann cells interact w/ one axon (1:1) and contributes to the formation of a single internode.
star-like glial cells of the CNS
Astrocytes
Lie near both neurons and blood vessels
Astrocytes
maintains homeostasis and chemical microenvironment of the brain and spinal cord
Astrocytes
provide SELECTIVE BARRIER between the ventricular fluid and the brain substance
Ependymal cells
TRUE/FALSE
Ependymal cells form a single layer of ciliated cuboidal epithelial cells that lines the entire ventricular system
FALSE
Ependymal cells form a SINGLE layer of CILIATED COLUMNAR epithelial cells that lines the entire ventricular system
What are the 4 supporting cells in neuroectodermal in origin?
4 supporting cells in neuroectodermal in origin
- oligodendrocytes
- Schwann cells
- astrocytes
- ependymal cells
TRUE/FALSE
Microglia and Connective tissue cells are supporting cells of ectoderm origin?
FALSE
Microglia and Connective tissue cells are supporting cells of MESODERM origin
They are mesodermal cells of monocyte lineage that migrate into the CNS along with blood vessels from the mesoderm surrounding the neural tube.
Microglia
Remember M=M=M!
Mesoderm= Monocyte= microglia
They are mesodermal cells that are normally present in small numbers in the brain and spinal cord and only proliferate in response to injury
Microglia
They are mesodermal cells that are normally present in small numbers (physiologic state) and migrate in the CNS, proliferate to become scavenger cells/specialized macrophages, removing damaged tissues (pathologic state)
Meninges surrounding the CNS
Connective tissue cells:
Dura, pia and arachnoid
Fibrous connective tissue surrounding the PNS
Epineurium, Perineurium and Endoneurium
They are collectively known as leptomeninges
Pia and Arachnoid
also known as Pachymeninx
Dura mater
it gives rise to the choroid plexus which produces CSF
Ependymal cells
Transient neurologic disorders that may primarily affect neuronal function alone (WITHOUT changes in the physical appearance of the cell)
Transient neurological disorders:
- seizures
- TIA (transient ischemic attacks) aka mild stroke
- hypokalemic paralysis
TRUE/FALSE
Oxidative metabolism of glucose in the mitochondria is vital for cell survival in the N.S.
TRUE
Oxidative metabolism of glucose in the mitochondria is vital for cell survival in the N.S.
Both Oxygen and Glucose supply is needed
Most ATP consumptions of the nervous system is for fueling what?
NA-K ATPase pump
-to restore the ion gradient altered by excitatory neurotransmission and neuronal activity
Critical for preventing excessive accumulation of glutamate (synaptic space) and calcium ions (in the cytosol), both of which are toxic to cells
ATP
Critical for preventing excessive accumulation of glutamate (synaptic space) and calcium ions (in the cytosol), both of which are toxic to cells
NECROSIS/APOPTOSIS
abrupt ATP depletion
Necrosis
abrupt ATP depletion- hypoxia, hypoglycemia, and ischemia
NECROSIS/APOPTOSIS
slower ATP depletion
Apoptosis
The acute depletion of ATP leads to neuronal damage from excessive accumulation of _______.
L-glutamate
NECROSIS/APOPTOSIS
This process is called Excitotoxicity
Necrosis
NECROSIS/APOPTOSIS
Excessive mechanical strain
Necrosis
Excessive mechanical strain- traumatic injury
NECROSIS/APOPTOSIS
excessive neuronal energy demands
Necrosis
excessive neuronal energy demands- Status Epilepticus
A form of programmed cell death that is essential for normal development and tissue homeostasis
Apoptosis
3 Important triggers of Apoptosis.
3 Important triggers of Apoptosis:
- DNA mutations
- Inflammatory mediators
- Abnormal accumulation of intracellular proteins, and oxidative stress
Homeostatic process by which cells degrade its organelles to maintain balance between synthesis, degradation, and subsequent turnover
Autophagy
3 specific pathologic reactions of neurons
ISCHEMIC CELL CHANGE
CENTRAL CHROMATOLYSIS
NEURONAL INCLUSIONS
It is a specific pathologic reaction that is due to deprivation of oxygen and cessation of oxidative metabolism
Ischemic cell change
A change in neuronal cell bodies after severe injury to the axons.
Central Chromatolysis
Also called as axonal reaction
Central Chromatolysis
Occurs in the distal part of axon when the parent body is destroyed or separated from the axon by disease or injury
Wallerian Degeneration
Causes of Ischemic cell change (5)
Causes of Ischemic cell change (5)
- loss of blood flow
- lack of O2 in the blood
- lack of substrates necessary for oxidative metabolism
- Poison (cyanide)
- blocking oxidative metabolism
TRUE/FALSE
After several (2-5) minutes, cells will exhibit REVERSIBLE changes
FALSE
After several (2-5) minutes, respiratory chain processes on the inner mitochondrial membrane ceases–> ATP stores depleted–> impaired ion channels –> anaerobic glycolysis–> lactate production–> further inhibition of mitochondrial function–> IRREVERSIBLE changes
TRUE/FALSE
8-12 hours: the neurons become smaller; its outline more angular
TRUE
8-12 hours: the neurons become SMALLER; its outline MORE SHARPLY BLUNT
cytoplasm: eosinophilic
nucleus: shrinks and becomes darkly stained (irreversible) complete dissolution of the neuron (red, dead neuron)
Irreversible changes that ultimately lead to cell death
- Excitotoxicity
- Accumulation of intracellular Ca++
- Generation fo free radicals
Unlike in the CNS, Wallerian degeneration occurs more rapidly in the peripheral nerves? true or false
TRUE
Impairment of axonal transport, disappearance of neurofibrils, and breaking up of axons into short fragments that will eventually disappear
Wallerian degeneration
- Impairment of axonal transport
- Disappearance of neurofibrils
- Breaking up of axons into short fragments that will eventually disappear
Central Chromatolysis is seen in small motor cells. True or false?
FALSE
Center chromatolsysis is seen in LARGE motor cells:
- spinal ventral horn cells
- motor nuclei of cranial nerves