CNS Class 1 - Cell Types, Injury & Death Flashcards
The body’s command center that originates from the brain. It controls movement, thoughts and automatic responses to the outside world, as well as other body systems and processes, such as digestion, breathing and sexual development.
Nervous System
The nervous system can be separated into the _______ nervous system and __________ nervous system.
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
A division of the nervous system made up of the brain and spinal cord that receives, interprets and responds to body tissues.
Central Nervous System (CNS)
The CNS is responsible for ____________ function and regulation of the autonomic nervous system, which is sometimes called the __________ nervous system as it pertains to basic physiological functions, like growth, respiration, sleep, digestion, excretion and homeostasis.
Hypothalamus
Vegetative Nervous System
The CNS is responsible for learning, cognition and memory, which help form our ___________.
Personality
Individual differences in characteristic patterns of thinking, feeling and behaving.
Personality
A division of the nervous system made up of everything outside the brain and spinal cord, which includes the cranial nerves, spinal nerves and their roots and branches, peripheral nerves and neuromuscular junctions.
Peripheral Nervous System (PNS)
The boundary between the CNS and PNS is the ______________ _______.
Intervertebral Foramen
The 2 categories of cells in the CNS are _______ and _________.
Neurons
Neuroglia
Name the parts of a neuron, as numbered in the following image.
1) Cell Body
2) Dendrites
3) Axon
4) Oligodendrocyte
5) Myelin Sheath
6) Synaptic End Bulbs
7) Axon Terminal
8) Node of Ranvier
The basic working unit of the brain. The parenchymal cell designed to transmit information to other nerve cells, muscle or gland cells.
Neuron (aka. Nerve Cell)
Functional cells of an organ.
Parenchymal Cells
Structural cells of an organ.
Stromal Cells
Part of a neuron that contains the nucleus and cytoplasm.
Cell Body (aka. Soma, Perikaryon)
Part of a neuron that extends from the cell body and often gives rise to many smaller branches before ending at the nerve terminals.
Axon
Part of a neuron that extend from the cell body and receive messages from other neurons.
Dendrites
Neurons send signals using ______ ___________, which are shifts in the neuron’s potential electric energy caused by the flow of charged particles in and out of the membrane of the neuron.
Action Potentials (APs)
When an action potential is generated, it’s carried along the axon to a ___________ ending. They can trigger both chemical and electrical ________.
Presynaptic
Synapses
The contact points where one neuron communicates with another. The dendrites are covered with ________ formed by the ends of axons from other neurons.
Synapses
What are the 4 types of neurons?
1) Unipolar
2) Bipolar
3) Pseudounipolar
4) Multipolar
A type of neuron that has only one process and is mostly found in invertebrates.
Unipolar
A type of neuron that is usually oval in shape and contains two processes, a dendrite that receives signals usually from the periphery and an axon that propagates the signal to the CNS.
Bipolar
_______ neurons are found in sensory organs, such as retina, olfactory epithelium and the auditory system.
Bipolar
A type of neuron that has two processes which fuse during their development into one short common axon. This axon splits into one branch that terminates in the periphery while the second branch terminates in the spinal cord. Stimuli from the periphery will bypass the cell body and reach the axon terminal without delay.
Pseuodounipolar
______________ and bipolar cells make up all the primary sensory neurons in the PNS.
Pseuodounipolar
Pseudounipolar neurons are found in sensory _______ of cranial and spinal nerves.
Ganglia
A type of neuron characterized by many dendrites that can originate from different regions of a cell body. They vary greatly in size, shape and complexity of their dendritic tree, and they represent the most common type of neuron in the CNS.
Multipolar
A diverse class of cells that provide developmental, physiological and metabolic support for neurons. They are responsible for maintaining homeostatic control and immune surveillance in the nervous system.
Neuroglia (aka. Glia, Glial Cells)
In both the PNS and CNS, there are neuroglia that __________ the axons.
Myelinate
A greatly extended and modified plasma membrane wrapped around the nerve axon in a spiral fashion. It functions to both insulate the axon and speed up electrical conduction.
Myelin Sheath
T/F - Each myelin-generating cell furnishes myelin for only one segment of any given axon.
True
The periodic interruptions where short portions of the axon are left uncovered by myelin, which are critical to the functioning of myelin.
Nodes of Ranvier
_______ cells myelinate axons in the PNS.
Schwann Cells
_________ cells regulate nutrient and neurotransmitter levels around neuron cell bodies in ganglia.
Satellite Cells
An immune system cell that removes cell debris, wastes and pathogens via phagocytosis in the CNS.
Microglia
The 3 main functions of __________ are:
- Maintain the blood brain barrier and preserve chemical environment by recycling ions and neurotransmitters
- Involved in gliosis
- Provide structural support
Astrocytes
A structure that protects neurons from toxins in the blood. It detects elements in blood that may be damaging to the neuron by closing gates, neutralizing the toxin or by dying.
Blood Brain Barrier (BBB)
T/F - The BBB is sensitive to all toxins, as it has evolved to determine toxic products, organic substances, foreign materials and metabolic wastes.
False - The BBB is sensitive to SOME toxins BUT NOT OTHERS, as it has evolved to determine toxic products, organic substances, foreign materials and metabolic wastes.
The BBB is not so good at recognizing contemporary chemicals and _______.
Alcohol
The restrictive nature of the BBB provides an obstacle for drug delivery to the CNS, and thus, major efforts have been made to generate methods to modulate or bypass it for delivery of ____________.
Therapeutics
A response to CNS damage and may persist for weeks or months after brain injury, occurring after infarct and is associated with infections and neoplasm, as well as demyelinating, toxic and metabolic diseases.
Gliosis (aka. Astrocytosis, Astrocytic Gliosis)
Astrocytes migrate to the site of neuronal death, clustering together to create a soft scar structure known as a _______.
Gliosis
The CNS does not use ___________ (second intention) repair, because this would result in an overly stiff, irritating and compressive scar.
Collagenous
The astrocytes remain alive for __ to __ years, adding to the gliosis if necessary, and possibly alerting ___________ if an immune response is needed.
1-2 years
Macrophages
T/F - Eventually the astrocytes die, but still remain in place as a soft scar.
True
It is thought that the glial scar limits _____ and prevents neuronal regeneration in the CNS by blocking regenerating axons from entering the damaged areas.
Edema
________________ myelinate axons in the CNS and provide an overall structural framework.
Oligodendrocytes
Resulting lesions of demyelinated neurons that show up as grey spots on imaging.
Plaques
_________ cells line ventricles in the brain and the central canal in the spinal cord, and are involved in the production of cerebrospinal fluid.
Ependymal Cells
Acute or chronic injury to the CNS, typically leading to irreversible damage. Some neurons die, and those that survive generally fail to grow new axons and re-establish synaptic connections.
Neuronal Resiliency
A common but poorly understood characteristic of ________ __________ is that specific neuronal types are disproportionately affected even though they all share the same causes of injury.
Neuronal Resiliency
Match the following examples with their cell types:
1) Hepatocytes
2) Neurons
3) Epithelial Cells
A) Labile Cells
B) Stable Cells
C) Permanent/Fixed Cells
1) Hepatocytes ~ B) Stable Cells
2) Neurons ~ C) Permanent/Fixed Cells
3) Epithelial Cells ~ A) Labile Cells
______ cells continue to divide and replicate throughout life, replacing cells that are continually being destroyed.
Labile Cells
______ cells normally stop dividing when growth ceases. They are capable of undergoing regeneration when confronted with an appropriate stimulus and are capable of reconstituting the tissue of origin. They will increase or decrease in number in response to usage or need.
Stable Cells
T/F - Neuroglia are labile cells, therefore are capable of reproduction to replace dead cells.
False - Neuroglia are STABLE cells, therefore are capable of reproduction to replace dead cells.
In situations where there is recurring cell death in ______ tissues, the replacement mechanism may begin to fail, leading to conditions like Multiple Sclerosis.
Stable
_________/_____ cells cannot undergo mitotic division and do not normally regenerate. Once destroyed, they are replaced by fibrous scar tissue that lacks the functional characteristics of the destroyed tissue.
Permanent/Fixed Cells
When people improve after CNS injuries, it is due to compensation via _______________ from other surrounding cells.
Neuroplasticity
T/F - Once a neuron is killed, it cannot be replaced .
True
The ability of the brain to form and recognize synaptic connections, especially in response to learning, experience or following injury.
Neuroplasticity
To immediately kill a neuron, the ____ ____ must be destroyed. If only the ____ is damaged, there is potential for repair, at least in peripheral nerves.
Cell Body
Axon
The most abundant excitatory neurotransmitter released by nerve cells in the brain. Too much has been associated with neurological diseases, such as Parkinson’s and ALS.
Glutamate
A layer of connective tissue surrounding each axon.
Endoneurium
Peripheral nerve axon injuries are classified by the level of injury to which 3 structures?
1) Axon
2) Myelin Sheath
3) Endoneurium
Name the grades of a nerve injury, as numbered in the following image.
1) Neurapraxia
2) Axonotmesis
3) Neurotmesis
Refers to when the axon is damaged, but the endoneurium and most of the surrounding myelin sheath is largely still intact.
Axonotmesis
T/F - There is potential for the axon to grow back with axonotmesis, as long as the injury is not too close to the cell body.
True
After nerve injury, the axon first undergoes _________ degeneration.
Wallerian Degeneration (aka. Anterograde, Orthograde)
An active process of degeneration of the distal end of an axon that occurs between 7 to 21 days after the injury.
Wallerian Degeneration (aka. Anterograde, Orthograde)
With Wallerian degeneration, the distal segment of the axon dies to the nearest ____ of _______. Once degeneration is complete, several axonal sprouts grow from the proximal segment, with any errant sprouts kept in line by the intact ___________.
Node of Ranvier
Endoneurium
T/F - The axon can grow back at a rate of approximately 2.5 mm per day, starting within 24 hours of the initial injury.
False - The axon can grow back at a rate of approximately 1.5 MM per day, starting within 24 hours of the initial injury.
Refers to if the endoneurium is no longer intact and surrounding myelin sheath is more severely damaged. Axonal regeneration is unlikely because the endoneurium is not there to contain and guide the axonal sprouts, therefore surgery is required to try to recover some function.
Neurotmesis
T/F - Injured nerve cells in the CNS typically do not regenerate.
True
Proteins expressed by oligodendrocytes that limit axon regeneration.
Inhibitory Molecules
A physical barrier to regeneration that forms after CNS injury and also contains inhibitory molecules that impede axon growth.
Astroglial Scar (aka. Astrocytosis, Gliosis)
CNS neurons do not __________ growth-associated genes to the same extent as do PNS neurons. Consequently, their ability to regenerate is limited even in the absence of inhibitors.
Upregulate
If a CNS axon or dendrite is fatally injured, or if a PNS axon is damaged too close to the cell body, the proximal segment of the axon will undergo __________ degeneration toward the cell body. The cell body may or may not die, but the cell cannot transmit.
Retrograde Degeneration
T/F - Retrograde degeneration occurs exclusively from anterograde degeneration.
False - Retrograde degeneration occurs IN ADDITION TO anterograde degeneration.
CNS cells are highly metabolically active for which they are dependent on _____ supply. The brain uses __ to __% of available oxygen or glucose at any given time.
Blood Supply
20-30%
CNS cells are especially sensitive to reduction in ______ and variations in blood _____.
Oxygen
Blood Sugar
With loss of oxygen, permanent damage usually begins to occur within __ to __ minutes.
4-10 minutes
The common causes of cell _____ in the CNS due to decreased ______ supply are:
- In Utero
- Birth-Related
- Fractures/Dislocations of Supporting Bones
- Compression
- Direct Trauma
- Concussion/Contusion
- Autoimmune Conditions
- Vascular Lesions
- Infection
- Poisons/Toxins
Cell Death
Oxygen Supply
Cell death in the CNS caused __ _____ may be due to:
- Genetic or congenital defect
- Injury to fetus
- Maternal high fever/illness (especially viral)
- Maternal drug/alcohol exposure
- Intrauterine infections
- Thyroid dysfunctions in mother/fetus
In Utero
Cell death in the CNS that is _____-_______ may be due to:
- Birth canal hypoxia
- Cord wrapped around neck of fetus
- Direct trauma from forceps used
Birth-Related
Cell death in the CNS can be caused by __________ or ____________ of supporting bones, such as the skull or vertebrae.
Fractures/Dislocations
Cell death in the CNS caused by ___________ may be due to:
- Edema
- Hematoma
- Tumour
Compression
T/F - CNS cells are very adversely affected by even small tumors or accumulations of fluid because of tight encasement in protective bony structures.
True
Cell death in the CNS caused by ______ ______ may be due to:
- Auto accident
- Fall
- Sports injury
- Penetrating injury
Direct Trauma
A concussion or contusion injury that occurs both at the site of trauma and the opposite side of the brain.
Coup-Contrecoup
Cell death in the CNS caused by __________ __________ include:
- Multiple Sclerosis attacking oligodendrocytes
- Diabetes resulting in blood sugar fluctuations leading to brain damage or seizures
- Lupus (SLE) causing seizures or psychoses
Autoimmune Conditions
Cell death in the CNS caused by ________ _______ may be due to:
- Stroke (occlusive or hemorrhagic infarction)
- Disorders creating hypoxic conditions (e.g. atherosclerosis in cerebral vasculature)
Vascular Lesions
Cell death in the CNS caused by _________ can be viral, bacterial or fungal (e.g. Candida).
Infection
_____________ infections common in the CNS are named by location and/or organism type.
Opportunistic
Match the following names with their organism type:
1) Granulomatous
2) Lymphocytic
3) Pyogenic
A) Common Bacteria
B) Viruses
C) Fungi, Yeast, Superbacteria
1) Granulomatous ~ C) Fungi, Yeast, Superbacteria
2) Lymphocytic ~ B) Viruses
3) Pyogenic ~ A) Common Bacteria
Match the following names with their location in the CNS:
1) Meningitis
2) Spinal Meningitis
3) Encephalitis
4) Myelitis
A) Brain Parenchyma
B) Brain Protective Membranes
C) Spinal Cord Parenchyma
D) Spinal Cord Membranes
1) Meningitis ~ B) Brain Protective Membranes
2) Spinal Meningitis ~ D) Spinal Cord Membranes
3) Encephalitis ~ A) Brain Parenchyma
4) Myelitis ~ C) Spinal Cord Parenchyma
Cell death in the CNS caused by _______ or ______ may be due to:
- Drugs (prescription and recreational)
- Chemicals of various types
- Alcohol
- Metals (e.g. mercury, lead, aluminum)
- Carbon monoxide
Poisons or Toxins
Poisons or toxins usually impair the cell’s ability to uptake or use ______ and the mechanism appears to be damaging or blocking receptor sites on the cell membrane.
Oxygen
Neurons are:
A) Labile Cells
B) Permanent/Fixed Cells
C) Stable Cells
D) None of the Above
B) Permanent/Fixed Cells
Neuroglia are:
A) Labile Cells
B) Permanent/Fixed Cells
C) Stable Cells
D) None of the Above
C) Stable Cells
The ability of the brain to form and reorganize synaptic connections is called:
A) Synaptic Rehab
B) Neurotmesis
C) Axonotmesis
D) Neuroplasticity
D) Neuroplasticity
If a CNS axon or dendrite is fatally injured, the proximal segment of the axon will undergo:
A) Retrograde Degeneration
B) Backwards Deformity
C) Astrocytosis
D) Neurotmesis
A) Retrograde Degeneration
Which of the following could compress CNS cells?
A) Edema
B) Hematoma
C) Tumor
D) All of the Above
D) All of the Above
This image is depicting:
A) Vascular Lesion
B) Bone Dislocation
C) Coup-Contrecoup
D) Infection
C) Coup-Contrecoup
An infection in the brain’s protective membranes is called:
A) Encephalitis
B) Meningitis
C) Myelitis
D) Lymphocytic
B) Meningitis
An infection in the brain caused by a virus is called:
A) Myelitis
B) Granulomatous
C) Pyogenic
D) Lymphocytic
D) Lymphocytic
Which of the following could impair the brain’s ability to use oxygen?
A) Carbon Monoxide
B) Aluminum
C) Alcohol
D) All of the Above
D) All of the Above
CNS cell death usually involves:
A) Decreased Oxygen
B) Increased Calcium
C) Decreased Serotonin
D) Excessive Sodium
A) Decreased Oxygen
