Exam 3 Flashcards
What is the functional unit of the nervous unit of the nervous system
The neuron
What are the parts of the neuron
The perikaryon (soma/body), dendrites, axon, and the axon terminal
What is the function of the dendrites
The afferent process that receives signals from other neurons
What is the function of the axon
The efferent process that synapses w/ another neuron or effector cell
What is synapse
The small gap btw 2 neuron cells where electrical or chemical reaction occurs
What is the pre synaptic cell
The cell prior to the synapse
What is the post synaptic cell
Cell after the synapse
What are characteristics of neurons
High O requirement, only uses glucose for energy, lack repro ability, can regenerate if the cell body is intact, and supported by glial cells
What are astrocytes
Glial cells that maintain the blood brain barrier, levels of neurotransmitter around synapses, regulates ions, and provides metabolic support
What are ependymal cells
Glial cells that line spinal cord and ventricles of the brain and produce CSF
What are oligodendrocytes
Glial cells that myelinate CNS axons and provide structural framework
What are microglia
Glial cells that form the brains immune cells removing dead cells and pathogens via phagocytosis
What are satellite cells
Glial cells that surround neuron cell bodies in ganglia of PNS regulating neurotransmitter levels
What are schwann cells
Glial cells that myelinate neurons in PNS, maintain, and regenerate neurons after injury
What is white brain matter
Lots of myelinated fibers
What is grey brain matter
Lots of neuron cell bodies
What are nodes of ranvier
Gaps in myeline sheath that is vital for accomplishing action potentials by enhancing conduction of nerve impulses
What are afferent nerve fibers
Sensory nerves fibers that send impulses from periphery to CNS
What are efferent nerve fibers
Motor nerve fibers that send impulses from CNS to periphery
What are mixed nerves
Nerves that have both sensory and motor functions primarily found in PNS
What is the autonomic nervous system
Automatic control of smooth muscle, cardiac muscle, and glands allowing afferent activity in terms of autonomic sensory function and efferent activity in terms of autonomic motor function
What is the somatic nervous system
Conscious control of skeletal muscle w/ afferent activities such as somatic sensory function such as muscles, skin, eyes, and ears and efferent w/ somatic motor function
What are the 3 states of a neuron
Resting, depolarization, and repolarization
What is the resting state
The cell membrane working to maintain electrical polarization using the sodium potassium pump and concentration gradients making it more negatively charged inside the cell
What is depolarization
When an action potential causes a sudden influx of Na where the stimulus occurs causing loss of membrane potential this occurs via passive diffusion
What is repolarization
When the Na channels shut, K channels open, passive diffusion occurs, the membrane potential shifs back toward the negative polarized state, and the sodium potassium pump takes over placing the K and Na back on the right side of the membrane
What is the depolarization threshold
The membrane potential that must be reached in order for an action potential to occur
What is an action potential
Wave of depolarization down the cell membrane
What is the all or nothing principle
Neuron completely depolarizes or not at all
What is the refractory period
Insensitive to new stimuli and can be absolute or relative
What is the absolute refractory period
Period of sodium influx and early potassium outflux keeping the cell cannot respond at all no matter how strong the stimulus is
What is relative refractory period
A strong stimulus at the end of repolarization may result in a new action potential
How do myelin sheaths cause conduction
The myelin sheath prevents sodium from crossing the cell membrane allowing the rapid conduction of the action potential to leap down the axon
What is the flow of the synapse down a pre synaptic neuron action potential
Axon, telodendron, and synaptic knob
What happens once the action potential hits the synaptic knob
Ca influxes, a neurotransmitter releases, they bind to receptors on the post synaptic neuron, and the synaptic transmission occurs
What are excitatory neurotransmitters
They open Na channels to depolarize the post-synaptic membrane causing an action potential
What are inhibitory neurotransmitters
Open Cl or K channels that hyperpolarize postsynaptic membrane preventing an action potential
What type of neurotransmitter is acetylcholine
Excitatory by stimulating skeletal and smooth muscle contraction and inhibitory by inhibiting cardiac muscle via parasympathetic nerves slowing HR
What type of neurotransmitter is epinephrine
Excitatory causing the fight or flight response in the sympathetic nervous system
How is epinephrine a hormone and neurotransmitter
Because it is also produced by the adrenal medulla as adrenaline along w/ the sympathetic nervous system
What type of neurotransmitter is norepinephrine
Excitatory as it is an arousal fight or flight response in the sympathetic nervous system
What type of neurotransmitter is dopamine
Excitatory as it stimulates the secretion of GH and inhibitory as it inhibits unnecessary movements and certain hormone secretion from the pituitary gland
What disease is associated w/ a decrease in dopamine neurons
Parkinson’s
What type of neurotransmitter is Gamma Aminobutyric Acid (GABA)
Inhibitory as it reduces neuronal excitability such as seizures
What type of neurotransmitter is glycine
Inhibitory by reducing neuronal excitability
What stops the acetylcholine signal
Acetylcholinesterase breaks down acetylcholine the products are reabsorbed by synaptic knob are reassembled and wait for next action potential in vesicles
What happens if acetylcholinesterase is inhibited
There will be a persistent stimulation of receptors causing salivation, diarrhea, vomiting, dyspnea, miosis, muscle fasciculations, and seizures
How is the norepinephrine signal stopped
At a slower process than stopping acetylcholine and occurs after the release into synaptic cleft and is reabsorbed by synaptic knob broken down by monoamine oxidase (MAO) if any is not reabsorbed in the synaptic knob it is broken down by catchol-O-methyl transferase (COMT)
What is contained in the CNS
Neuron cell bodies, myelinated, unmyelinated nerve fibers, and glial cells
What are the parts of the brain
Cerebrum, cerebellum, diencephalon, brainstem, meninges, cerebrospinal fluid, blood brain barrier, and cranial nerves
What is the cerebrum
The largest part of the brain in domestic animals, area of learning and intelligence, the gyri is separated by fissues and sulci, where sensory info is received and interpreted, voluntary motor control is initiated here, and integration of neuron info such as emotional response, learning, memory, and recall
What divides the cerebrum into 2 hemipheres
The longitudinal fissure
What is the function of the corpus callosum in the cerebrum
Allows for communication btw the left and right hemipheres
What does the sulci do
Divides the hemispheres into lobes superficially
What are the different lobes of the brain
Frontal, parietal, occipital, and temporal
What is the cerebellum
Second largest part, contains grey matter cortex w/ white matter underneath, coordinates movement, balance, posture, and complex reflexes, and results in hypermetria if damage/disease which is exaggerated movements
What is the diencephalon
Passageway btw cerebrum and brainstem and contains the thalamus, hypothalamus, and pituitary
What is the function of the thalmus
Regulates the sensory input to the cerebrum
What is the function of the hypothalamus
Nervous system-endocrine system interface w/ temperature control, thirst, hunger, and anger response
What is the pituitary
Master gland of the endocrine system
What is the brainstem
The connection btw the spinal cord and the rest of the brain, it is the most primitive part for autonomic control of the cardiovascular system, respiration, swallowing, and vomiting, and contains the medulla oblongota, pons, and midbrain
What are the meninges
Connective tissue layers surrounding the brain/spinal cord supplying nutrient, oxygen, and cushioning, the layers are the dura mater, arachnod, and pia mater
What is dura mater
Tough and fibrous superficial layer of the meninges
What is the arachnoid
Delicate spider web looking layer that contains CSF
What is the pia mater
Thin layer that lies on the brain/spinal cord
What is the cerebrospinal fluid
Fluid btw layers of meninges, in canals/ventricles of the brain, and spinal cord that influences autonomic functions
What is the blood brain barrier
Tightly constructed capillary wall w/ no fenestrations, astrocytes add additional support, and prevents drugs, proteins, and ions from passing from the blood to the brain
How many cranial nerves are there
12 pairs in the pNS that originate directly from the brain
What is the mnemonic for remembering the cranial nerves
On (olfactory) old (optic), Olympus’ (oculomotor) towering (trochlear) tops (trigeminal) a (abducent) friendly (facial) viking (vestibulocochlear) grows (glossopharyngeal) vines (vagus) and (accessory) hops (hypoglossal)
What is the mnemonic for remembering the type of axon each cranial nerve has
Some (sensory) say (sensory) marry (motor) money (motor) but (both) my (motor) brother (both) says (sensory) big (both) brains (both) matter (motor) more (motor)
What is the function of the olfactory nerve
Sense of smell
What is the function of the optic nerve
Sences of vision
What is the spinal cord
Caudal continuation of the brainstem outside of the skull conducting sensory and motor info, contains neuron cell bodies and synapses, and nerve roots emerge btw adjacent vertebrae dorsal nerve roots being sensory afferent and ventral nerve roots being motor efferent
What does the left hemisphere do signal wise
Receives sensory info from the right side of the body and provides motor control to the right side of the body
What does the right hemisphere do signal wise
Recieves sensory info from the left side of the body and provides motor control to the left side of the body
What are the 2 parts of the ANS
Sympathetic and parasympathetic
What is the sympathetic nervous system
The thoracolumbar system that develops the fight or flight response and the body’s way of coping in emergency situations
What are is the parasympathetic nervous system
The cranial sacral system, that rest and restores the body to bring it back to a resting state replacing the resources used during an emergency
What is an efferent motor nerve composed of
2 neurons and a ganglion
What are preganglionic neuron
Cell body in brain or spinal cord that sends a signal
What is a ganglion
Cluster of neuron cell bodies such as a collection of synapses outside the CNS
What is the postganglionic neuron
Carries the impulse to the target organ
What is the description of sympathetic nervous system motor nerve
The postganglionic neuron is much longer than its preganglionic neuron
What is the impulse flow of a neuron w/ the sympathetic nervous system
The signal exits the thoracolumbar spine and terminates near the spinal cord and may synapse w/ a neuron w/in the ganglion chain or pass thru the ganglionic chain and synapse w/ neuron located beyond the sympthetic chain
How many postganglionic neurons are there for one preganglionic neurons in the SNS
Multiple
Where is the sympathetic ganglion chain
Connected by the sympathetic trunk
What is the description of parasympathetic nervous system motor neuron
The postganglionic neuron is much shorter than its preganglionic neuron
What is the impulse flow of a neuron in parasympathetic nervous system
Preganglionic neuron originates from the nuclei or from the sacral spine and travels to its target organ
What is the primary neurotransmitter in the SNS
Norepinephrine which is released by adrenergic neurons
What are the adrenergic receptors for norepinephrine in the SNS
Alpha 1-adrenergic receptors, beta 1-adrenergic receptors, and beta 2 adrenergic receptors
What do alpha 1 adrenergic receptors do in the SNS
Vasoconstrictions of skin, GIT, and kidney
What do beta 1-adrenergic receptors in the SNS
Increases HR and force of cardiac contraction
What does beta 2-adrenergic receptors do in the SNS
Bronchodilation
What is the primary neurotransmitter for the parasympathetic nervous system
Acetylcholine
What type of neurons release acetylcholine
Cholinergic in the pre and post ganglions in the parasympathetic and preganglion in sympathetic
What are the cholinergic receptors for acetylcholine
Nicotinic and muscarinic
Where are the nicotinic receptors
Found on the postganglionic neurons of both the sympathetic and parasympathetic nervous system btw motor neurons and muscle
Where are the muscarinic receptors
Found on target organs and tissues supplied by postganglionic neuron of the PNS
What are reflexes
Rapid autonomic responses to stimuli that protects the body and maintain homeostasis
What are the two types of autonomic reflexes
Contralateral and ipsilateral
What are contralateral reflexes
Reflexes on the other half of the body from the stimuli
What are ipsilateral
Reflexes on the same side of the body from the stimuli
What is the reflex arc
The sensory receptor detects a change, the sensory receptor fires an action potential along the sensory neuron to gray matter of the spinal cord or brain stem, sensory neuron synapses w/ interneurons, the integrated response of the reflex is sent out from the spinal cord or brainstem by the motor neuron leading to contraction inhibition of muscle or gland
What is the stretch reflex
Ipsilateral reflex occurs w/ a simple monosynaptic arc the muscle spindle senses a stretch sending an impulse to the sensory neuron of the spinal cord, synapse occurs w/ the motor neuron to the same muscle, contraction of the same muscle occurs inhibiting the opposing muscle, and sends a sensory signal to the brain
What does the stretch reflex maintain and prevent in muscles
Maintains tension and muscle tone and prevents overstretching
What is the withdrawal reflex
Ipsilateral reflex of several interneuron synapses that results in muscle contraction/flexion while relaxing opposing muscle this reflex occurs before the brain is aware of the painful stimulus
What is crossed extensor reflex
A contralateral reflex where sensory neuron synapses w/ interneurons, the flexor muscles in ipsilateral limb contract while opposing muscle groups are inhibited and the extensor muscle in contralateral limb contract so that limb can support your full weight
Where is the inhibitory effect on the reflex arc
The CNS cranial to the site where the sensory neuron enters the spinal cord/brain stem
What is a hyperreflexive
Lack of inhibition to reflexes causing them to be more exaggerated than normal
What is a hyporeflexive
Lack of reflex present
What causes a hyperreflexive
If an injury occurs in the cranial aspect of the CNS and reflex arcs are intact caudal to the trauma
What causes hyporeflexive
If injury occurs where the reflex arc enters or leaves the spinal cord
What is the palpebral reflex
Sensory receptors on skin of the eyes send a signal to cranial nerve 5 in the pons and sends a signal to cranial nerve 7 to stimulate a blink
What happens to the interneurons in the pons while under anesthesia
They are depressed resulting in a loss of palpebral reflex
What is the pupillary light reflex
Retina senses the light, a signal to cranial nerve 2 that is transmitted to the optic chiasm then to the diencephalon which sends a response signal to cranial nerve 3 resulting in an ipsilateral pupil constricts in a strong and a weak contralateral pupil constriction
What does a neurologic exam include
Testing reflexes both for withdrawal and patellar, palpate along the spine looking for signs of pains, movement of neck, cranial nerve exam, and evaluate gait
What are the 3 types of ataxia
Proprioceptive, cerebellar, and vestibular
What is proprioceptive ataxia and what are common tests for it
Unawareness of limbs and the space around them this can be identified by listening for shuffling of the dogs feet and placing their foot dorsal side down
What is cerebellar ataxia
Lack of fine motor control and can be diagnosed w/ a hypermetric gait
What is vestibular ataxia
Inner ear issue that causes uncordination typically the animal stumbles or tilts its head in the direction of the issue
What are diagnostics for neurologic issues
PE, neurolocalization via neuro exam, minimum databases such as CBC, chem, and UA, rads of spine or skull, MRI, CT, myelograms, CSF tap/analysis, electromyograph, and electroencephalograph
What is the downfall to using a radiograph as a diagnostic for neuro issues
The radiograph does not show any soft tissue such as the spinal cord itself
What diagnostic shows soft tissue
MRI
Where do we tap for CSF fluid
At the base of the skull or right behind the lumbar vertebrae
How do we handle large animals and small animals differently w/ CSF taps
Large animals we sedate while small animals are anesthetize
What is an electromyograph
An EMG asses the electrical activity of the muscle to identify nerve disease
What is an electroencephalograph
An EEG assess the electrical activity of the brain
What is the BAER hearing test
The brainstem auditory evoked response test establishes if the animal or not by administering auditory stimuli to watch for a reaction
Why do dogs w/ brain tumors have different neurologic symptoms
Tumors in different locations will cause different symptoms
What is wobblers caused by
Compression of the cervical vertebrae typically appears in younger large dogs such as great danes
What is intervertebral disc disease
When the soft tissue disk becomes compressed by the vertebral bone
What part of the nervous system does tetanus affect
The PNS
What are common symptoms of distemper
Twitches in the neck and face, respiratory symptoms, diarrhea, vomiting, teeth abnormalities, and hyperkeratosis
What is DAMN IT-V
Reasons why different neurological issues occur such as degenerative or developmental, anomalous or autoimmune, metabolic, nutritional or neoplastic, infectious, inflammatory, immune mediated, or idiopathic, trauma or toxic, and vascular
What are the 2 categories of IVDD
Degenerative or traumatic
What is type 1 degenerative IVDD
The nucleus pulposus degeneration and extrusion from the surrounding annulus fibrosis
What is type 2 degenerative IVDD
Annulus fibrosis degenerates and protrudes
What is traumatic IVDD
Acute non compressive nucleus pulposus extrusion
What are the treatments for IVDD
Drug therapy w/ anti-inflammatories (NSAID vs corticosteroid), analgesias (NSAID, gaba, and or opioids), muscle relaxers (alprazolam and methocarbamol), and cage rest or surgery
What is tick paralysis
Rapidly progressive motor paralysis due to a toxin in the tick’s saliva that attacks the nervous system
What are symptoms of tick paralysis
Presenting 3-9 days after tick attaches the dog may have a loss/change in voice, ataxia, abnormal respirations/rate, gagging, coughing, vomiting, and mydriasis
What is the difference btw vomiting and regurgitation
Vomiting takes abdominal effort to force food up and out of the stomach while regurgitation is a random blah of food that was likely stuck in the esophagus
What is mysthenia gravis
A rare autoimmune disorder where Ab form against nicotinic acetylcholine post synaptic receptors at the neuromuscular junction of skeletal muscles and can causes megaesophagus this can be tested w/ a blood test to check for Ab, tensilon test, and fatigue test
How is myasthenia gravis treated
Acetylcholinesterase inhibition, immunosuppressant therapy, and a bailey chair
What is the process of the rabies virus
Enters tissue thru saliva of infected animal, virus replicates in muscle near bite, moves up PNS to CNS, ascends to spinal cord, reaches brain and causes fatel encephalitis, and enters salivary glands and other organs of victim
What are the types of seizures
Generalized/grand mal, focal, psychomotor, and cluster
What is a psychomotor seizure
Odd behavior such as chasing tail or appearing to see things that arent there
What are cluster seizures
A group of seizures w/in a shorter than normal interval clinically defined as 2 or more seizures w/in a 24 hr period
What are the stages of seizures
Prodromal, aural, ictal, and postictal
What is the prodromal phase of a seizure
The animal experiences an indication of forthcoming seizure hrs to days before
What is the aural phase of a seizure
This is the very start of the seizure where behavior changes may be apparent
What is the ictal phase of a seizure
The seizure itself
What is the postictal phase
Consists of transient neurological and behaviour changes which lasts from hrs to days
What are at home treatment options for seizures
Phenobarbital, potassium bromide, levetiracetam (keppra), and zonisamide
What is automatisms
Repetitive motor activity that resembles movement under voluntary control such as lip smacking, licking, or chewing
What is an atonic seizure
Sudden loss of muscle tone lasting several seconds or more not following a tonic or myoclonic event
What is a generalized seizure
Seizures originating from both hemispheres of the brain
What is idiopathic epilepsy
Epilepsy w/o an identifiable structural cause typically assumed to be genetic
What is interictal period
The time btw seizures
What is myoclonic seizure
Sudden brief contractions of a muscle or group of muscles
What is the refractory epilepsy
Seizures that occur even during treatment w/ therapeutic doses of antiepileptic medication and medication stops being effective
What is status epilepticus
A serious condition where seizures follow closely on one another w/o a break or where a single seizure lasts more than 5 mins
What is a tonic seizure
A sustained increase in muscle tone lasting up to several mins
What is a tonic clonic seizure
A seizure where the tonic phase is followed by shorter clonic movements
