Unit 6 Patho Flashcards
What are the Glia cells in the CNS?
Oligodendrocytes
Astrocytes
Ependymal
Micoglia
What are the Glia cells in the PNS
Schwann
Satellite
What are the two parts of a synapse?
Presynaptic (Axon terminal) and
Postsynaptic (Membrane of other cell)
Which neurocrine primarily act on a synapse and elicit rapid responses?
Neurotransmitters
Which neurocrine act on both synaptic and non-synaptic site and act more slowly?
Neuromodulators
Which neurocrine secretes into the blood and are distributed throughout the body?
Neurohormones
Which neurocrine-Amines play a role in allergic reactions in addition to serving as a neurotransmitter acting on reception the brain?
Histamine
Which two neurocrine-Amines influence attention, motivation, wakefulness, movement, and memory?
Serotonin and Dopamine
Which Neuro-Amines are major neurotransmitters of the PNS autonomic division controlling smooth and cardiac muscles, glands, and the CNS?
Epinephrine and Norepinephrine
Which Neurocrine-Amino acid is primarily excitatory neurotransmitter in the CNS?
Glutamate
Which Neurocrine-Amino Acid is the main inhibitory neurotransmitter in the CNS?
GABA
One presynaptic neuron branches to affect a larger number or postsynaptic neurons is an example of which pathway?
1) Convergent Pathway
2) Divergent Pathway
Divergent Pathway
Many presynaptic neurons provide input to influence a smaller number of postsynaptic neurons is an example of which pathway?
1) Convergent Pathway
2) Divergent Pathway
Convergent Pathway
What are the 3 classifications of a nerve injury?
Neuroplasia
Axonotomesis
Neurotomesis
What happens if the cell body (soma) of a neuron is damaged?
The neuron would not regenerate
What happens if the axon of a neuron or if the terminal branches gets damaged?
They can regenerate and the speed of the growth is about 1 millimeter per day
What happens during neuroplasia?
Demyelination and the axon is still intact, but the myeline sheath is compressed. (Least severe)
What happens during Axonotomesis in nerve injury?
Demyelination and Axon loss, the endoneurium is still intact and the neuron can still regrow. However the axon terminal will die. Undergoes wallgrian degeneration.
What happens during Neurotomesis in nerve injury?
Demyelination, axon loss, damage to the endoneurium ( Fair growth), perineurium (poor growth), epineurium (No growth)
What is the difference between a weak stimulus and a strong stimulus? In terms of action potential.
The frequency of an action potential firing indicates the strength of a stimulus.
Weak stimulus release little neurotransmitter.
Strong stimulus cause more action potential and release more neurotransmitter.
What is slow synaptic potential in the postsynaptic responses?
The second messenger system use to create slow synaptic potentials and long term effect.
What is fast synaptic potential in the postsynaptic response?
When ion channels open directly by neurotransmitters on receptor channels for rapid, short acting effects.
Depolarizing synaptic potentials are called:
Excitatory postsynaptic potentials (EPSP)
[Makes cell more likely to fire action potential]
Hyperpolarizing synaptic potentials are:
Inhibitory postsynaptic potentials (IPSP)
[Less likely to fire action potential]
What is temporal summation?
Temporal summation occurs when two graded potentials from one presynaptic neurons occur close together in time.
What is the difference between no summation and summation causing action potential in a Temporal Summation?
No summation: is when two subthresholds graded potentials will not initiate an action potential if they are far apart in time.
Summation causing action potential: Is when two subthresholds potentials arrive at the trigger zone within a short period of time. They sum up and initiate an action potential.
What is synaptic inhibition, what occurs?
One inhibitory postsynaptic potential (IPSP) sums with two excitatory postsynaptic potentials (EPSPs) to prevent an action potential in the postsynaptic cell.
Describe the sequence of events during the generation of an action potential.
The action potential begins with a resting state, ➡️ it then involves depolarization (influx of sodium), it reaches a threshold opening the voltage gated sodium channels. [This causes a rapid incline causing membrane potential to spike] ➡️ it then goes to a repolarization state (due to potassium efflux) ➡️ it then restores to the resting membrane
What is the role of oligodendricytes?
Myelinate CNS neurons
What is the role of astrocytes?
—To maintain the environment surrounding the neurons
—Helps regulate what does and doesn’t not go from the blood stream in the systematic circulation into bloodstream supplying the brain (Blood-brain barrier)
(Makes up half of all cells in brain)
What is the role in Ependymal cells?
—Produce cerebral spinal fluid
—Creates a selective permeable barrier
What is the role of Microglia?
—Phagocytosis; They engolf anything that should not be there
—Play an immune Role
What is the role of Schwann cells?
To myelinate PNS neurons
What is the role of Satellite cells?
—Myelinate ganglia in PNS
—Protect and maintain the soma
[Ganglia is the cell body of the PNS]
What are the roles of Afferent fibers?
In charge of sensory
(Carry sensory info from receptors to CNS)
What are the roles of efferent fibers?
In charge of motor
(Carry motor info from the brain to the PNS)
What are the 3 types of neurons? And their functions.
—Multipolar Neuron- usually have 2 or more dendrites, have a single axon, most common in body. Gives signals through system.
—Pseudounipolar neuron- Has one soma and no dendrites, and has 2 axonal branches; Exclusive to sensory neurons. One branch extends to the PNS and the other to the CNS
—Bipolar neuron- Has one axon and one dendrite; often act as sensory neurons. In charge of hearing, sight, and smell.
What are 2 key factors that influence speed of action potentials?
—Diameter of the axon (Larger is faster)
—Resistance of axon membrane to ion leakage of the cell
(more leak resistance is faster)
what happens during the Absolute refractory period of action potential?
No stimulus can trigger another action potential regardless of size.
What happens during the Relative refectory period in action potential?
Only a target larger than the normal stimulus can initiate a new action potential.
what is Guillain-Barré (GBS)?
A demyelinating, autoimmune disease, a disease that affects the PNS; often triggered by infection
[Autoimmune polyneuropathy]
How might a patient present with GBS in the clinic?
Weakness in the feet and legs
Numbness and tingling
May have difficulties with eye and facial muscles (blinking, speaking, laughing, chewing or swallowing)
Pain/Fatigue and unsteadiness when walking
How might GBS affect the body, what are red flags?
Patients may experience rapid HR, difficulty breathing, and fluctuations in BP
How can you diagnose GBS?
Spinal tap test: withdraw small amounts of cerebrospinal fluid in the low back
Electromyography: Thin-needle electrodes are inserted to the muscles, these electrodes measure muscle activity.
How can GBS be treated?
Plasma Exchange, which can eliminate antibodies present in the plasma that contributes on the immune system attack on the nerves.
PT: Helps patients regain strength and can help cope with fatigue
Recovery begins, usually lasting 6 months to a year, although some may take longer.
Around 80% can walk independently 6 months after diagnosis.
What is polyneuropathy?
The dysfunction of nerves.
May cause lower motor neuron, somatosensory, and autonomic abnormalities.
Disorders that cause polyneuropathy may affect nerves in different ways, such as:
May affect myelin more than axon
Or
May affect axons more than myelin
If a polyneuropathy is mainly axonal loss, what is affected?
The axons of the peripheral nerves are being injured.
If a polyneuropathy of demyelinating neuron, what is affected?
The myelin that form in the myelin sheath on the axon are the main thing being affected.
What is the most common polyneuropathy symptoms?
Somatosensory abnormalities of the bilateral distal limbs
-starts with numbness in the toes, then moves in the feet. It then moves more proximal towards the center of the body. Once it reaches the knees the hands become affected.
T/F. With a polyneuropathy progression would we see an upper motor neuron abnormalities.
False
We would see lower motor neuron abnormalities, this includes: weakness and loss of muscle stretch reflexes
What is an example of an autoimmune polyneuropathy?
1) CVA/Stroke
2) Guillain-Barré Syndrome
3) Cushing Disease
4) Addison’s Disease
2) Guillain-Barré Syndrome
Of these choices, GBS is the only choice that deals with a polyneuropathy (Demyelinating) disorder.
What is the most common polyneuropathy?
1) Hashimoto’s Thyroiditis
2) Polio
3) Parkinson’s Disease
4) Diabetes Mellitus
4) Diabetes Mellitus
Where are the lesion locations for an upper motor neuron (UMN) lesion and a lower motor neuron lesion (LMN)?
UMN is in the CNS: Above ventral horn in spinal cord or above the nuclei of the cranial nerves.
LMN is primarily in the PNS: ventral horn (CNS), motor nerve fibers (PNS) , or neuromuscular junction (PNS)
What would be the presentation or muscle tone of UMN compared to LMN?
UMN would have increased muscle tone (Spasticity and/or clonus)
-Clonus is repetitive movements
LMN would have decreased muscles tone (Flaccid)
How would you describe the deep tendon reflexes on UMN compared to LMN?
UMN would be increased
LMN would be decreased or absent
Where do myelinated axons form in the CNS?
White matter in bundles called tracts
Where do the nerve cell bodies (soma) form?
In the Grey matter; cerebral cortex.
Which of the following is consistent with a lower motor neuron lesion disorder?
1) Spasticity
2) Hyperreflexia
3) Flaccid muscle paralysis
4) Hypertonicity
3) Flaccid muscle paralysis
What is Poliomyelitis (Polio)?
Polio is a viral infection caused by poliovirus which is a single strand RNA virus protected by capsid (A protein coat)
What happens when poliovirus enters the body?
They bind to the mucosal cells of the small intestine and oropharynx, it then enters the cell and releases RNA. With RNA they make daughter cells which “hijack” the cell and force proteins to make viral proteins instead.
What are red flags associated with Poliomyelitis (Polio)
Polio cause inflammation and damage to the spinal cord. As the affected motor neurons die, the muscles of the trunk and limbs no longer receive signals from the brain
Because of this⬆️, this may cause muscles to atrophy.
What is the most significant complication of polio and why?
Bulbar polio is the most significant complication because it affects the motor nerves innervated with speaking and swallowing; these nerves are also involved with the diaphragm, if this is damaged it will impair breathing.
How is Polio transmitted person to person?
Mainly affects children by fecal-oral transmission
(The virus enters through contaminated food and water)
Also when an infected person sneezes or coughs, the virus is spread through droplets into the local area.
How might a patient with Polio present?
Although most symptoms are not visible, they may have headaches, fever, fatigue, loss of muscle reflexes and paralysis.
Infants can develop acute paralysis where they go limp (“Floppy baby syndrome”)
What are some treatment options for Polio?
There is NO specific treatment
Try to support individuals with acute infection (Pain meds, respiratory support, vaccine)
Vaccines include Inactivated poliovirus vaccine (IPV) dead or inactive poilio is injected into muscle.
[Both vaccines have to be administered before diagnosis]
Oral poliovirus vaccine (OPV) a weakened state of live virus
T/F. Action potentials are considered an all or nothing phenomenon.
True
It either happens or it doesn’t
What makes Acetylcholine difference compared to the other major neurocrines? What is it synthesized from?
Acetylcholine (Ach) is in its own chemicals class and is
Synthesized from choline and acetyl CoA.
Neurons that secrete AcH and receptors that bind AcH are characterized as:
Cholinergic
(Function in signal transduction of the somatic and autonomic nervous system)
Cholinergic receptors come in two subtypes, what are they and describe them.
—Cholinergic Nicotinic: found in skeletal muscle in autonomic division of PNS and CNS
—Cholinergic Muscarinic: found in the CNS and autonomic parasympathetic division of PNS (Smooth and cardiac muscle, endocrine and exocrine glands)
