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86 Cards in this Set

  • Front
  • Back
A nerve impulse is also known as this.
Action Potential
These 2 systems are responsible for maintaining homeostasis.
Nervous & Endocrine
The 4 things the nervous system is responsible for.
Perceptions, behaivors, memories, voluntary movements.
Define "nerve".
A bundle of hundreds to thousands of axons, assoc. connective tissue, and blood vessles that lies outside the brain and spinal cord. Each follows a defined path, specific region.
Define ganglia.
A group of neuronal cell bodies outside of the CNS.
Identify the 3 basic functions of the nervous system and expain their types.
1. Sensory function - Detects internal & external stimuli.

2. Integrative funcion - Processes sensory information by analyzing, storing, and making decisions. Perception occurs here.

3. Motor function - Elicits an appropriate motor response by activating effectors.
How many neurons are in the brain?
100 billion
The 2 types of cells that make up nervous tissue and their functions.
Neurons- provide most functions - sensing, thinking, remembering, muscle activity, regulating secretions.

neurolglia- Support, nourish, protect the neurons & maintain homeostasis in the interstitial fluid that bathes them.
Define stimulus.
Any change in the enviornment strong enough to generate an action potential.
Define action potential.
AKA nerve impulse, and electrical signal that propagates along the surface of the membrane of a neuron.
Explain the size and speed of neurons.
Some are tiny, and propagate information over a short distance. Some are the longest cells in the body. They can travel from 1 to 280 miles per hour.
3 parts of a neuron.
1. Cell body
2, Axon
3. Dendrites
Define axon terminal.
Where the axon & its collateral end in many proccesses.
Define synapse.
The site of communication between two neurons or between a neuron and an effector cell.
The tips of axon terminals swell at these structures.
Synaptic end bulb.
Define synaptic vescicle.
A membrane enclosed sac a the synaptic end bulb that stores a neurotransmitter.
What is the function of a neurotransmitter?
To excite or inhibit other neurons, muscle fibers, or gland celss.
Name the 3 functional types of neurons.
1. Sensory/afferent
2. Motor/efferent
3. Interneurons/Association
Define sensory neuron.
Carries information to the CNS.
Define Motor neuron.
Carries information away from the CNS to an effector.
Define interneuron.
AKA association neuron, process information and elicits a motor response.
Define neuroglia and their purpose.
AKA glia, 1/2 volume of CNS. They are smaller & more numerous than neurons. Do not propagate action potentials, but divide & multiply to fill empty spaces.
What are brain tumors derived from glia called, & why are they highly malignant?
Gliomas, they are highly malignant because they grow rapidly (due to glia multiplying rapidly)
The 4 types of neuroglia in the CNS & state their functions.
1. Astrocytes - Able to support neurons through microfilaments, create blood brain barrier, maintain appropriate chemical enviornment for nerve impulses.
2. Oligodenrocytes - form & maintain myelin sheath.
3. Microglia - Phagocytes that remove cellular debris, microbes & damaged tissue.
4. Ependymal cells - microvilli and cilia, line ventricles of brain & spinal cord, produce monitor circulate cerebospinal fluid. Form blood cerebrospinal fluid barrier.
The 2 types of glial cells in the PNS & their functions.
1. Schwann cells - encircle PNS axons, myelinate.

2. Satellite cells - Structural support & regulation of exchanges between neuronal cells & fluid.
What is the difference between a Schwann cell and a oligodendrocyte?
a) In the CNS b) Myelinates several axons

Schwann Cell
a) In the PNS B) myelinates single axon c) participate in axon regeneration
Define myelination, unmyelation, demyelation
Myelination - Axons surrounded by a multilayered lipid & protein covereing

Unmyeliated - Axons with no myelination.

Demyelination - loss or destruction of myelin sheaths such as in MS or Tay Sachs.
Why are an infant;s responses to stimuli less rapid & coordinated than an older child's?
The amount of myelin increases from birth to maturity. Because its presence greatly increases the speed of nerve impulses, an infant would have less rapid responses due to less myelination.
Define nodes of ranvier.
Gaps in the myelin sheath, which allow nerve impulses to travel via jumping from node to node.
Define membrane potential.
An electrical potential difference (voltage) across the plasma membrane of excitable cells.
Electrochemical gradient.
a chemical concentration difference plus an electrical difference. (When Ion channels are open, specific ions are allowed to move accross the plasma membrane, down their elctro. gradient.
Name the four types of ion channels.
1. Leakage channels
2. Ligand-gated channel
3. Mechanically gated
4. Voltage gated
Define leakage channel.
An ion channel with gates that randomlly alternate between open & closed.
What ion is a membrane more permeable to and why?
More permeable to potassium (k+) than sodium (Na) because plasma membranes have many more k+ channels that leak more.
Define a ligund gated channel and describe what might open it.
opens and closes in response to a specific chemical stimulus such as NTs, hormones, ions.
Define a mechanically gated channel and describe what might open it.
Open and closes in response to mechanical stimulation such as touch, pressure, tissue stretching. Example: Auditory receptors in ear.
Describe a voltage gated channel and what its main purpose it.
Opens in response to a change in membrane potential (voltage). They participate in generation & conduction of action potentials.
What is the typical resting membrane potential?
Explaint the "All or nothing" theory.
Stimulus must have the capacity to change the membrane potential to threshold in order to cause a reaction.
What is the threshold?
-55, the point to which a stimulus must change the membrane potention in order to cause a reaction.
What is depolarization?
The negative membrane potential becomes more positive, peaks at -30.
What is repolarization?
The membrane potential is returned to the resting membrane potention by becoming more and more negative.
What is the refractory period?
mV is too low for a stimulus to reach the threshold. Cannot generate another action potential. (Anesthesia causes this).
What is hyperpolarization?
The stage following repolarization in which the membrane potential becomes more negative than the resting potential. Goes to about -90.
Explain the difference between continous and saltatory conduction.
Continous - unmyelinated axons, slower, opens channels in succession.

Saltatory - myelinaetd, faster, impulse jumpes from node to node due to many voltage channels.
Name 3 things that affect the speed of propagation and describe them.
1. Amount of myelination -More rapid propagation along myelinated due to "jumping"
2. Axon Diameter - Large-diameter axons propagate faster than small ones due to surface area.
3. Temperature. Lower temperature equals lower speeds!
Define EPSP and explain what it does to the membrane threshold.
Exictatory postsynaptic potential - Depolarizes the membrane, bringing it closer to the threshold therefore exitactory.
Define IPSP and explain what it does to the membrane potential.
Ihibitory postsynaptic membrane - hyperpolarizes membrane, bringing it farther from threshold, therefore inhibitory.
Why does the same neurotransmitter work differently at different synapses?
It can be excitatory or inhibitory depending on what receptor it binds to, and which channel it ulitmatley opens.
Explain 3 things that may happen to NT's after a reaction.
1. They may diffuse away into other parts of the interstital fluid.
2. Enzymes may phagocyte them.
3. Reuptake (Nts may be recycled back to synabtic bulb)
Define Multiple Sclerosis.
Autoimmune disease that causes progressive destruction of myelin sheaths surrounding the neurons in the CNS.
Define Epilepsy
Short, recurrent attacks of malfunction (epileptic seizures) initated by abnormal electrical discharges from millions of neurons in the brain at once. Can be caused by brain damage, metabolic disturbances, infections, toxins, head injuries, tumors, and abcesses. Also fevers under age 2.
Gullian Barre Syndrome
Demylination occuring from macrophages stripping away myelin from axons in PNS. Causes paralysis.
Malignant tumor consisting of immature nerve cells (neuroblasts), rare. Most common tumor in infants.
Any disorder that affects nervous sytem, cranial & spinal such as Bell's Palsy.
Fatal diease by a virus that reaches CNS vis axonal transport. Bite from infected animal. Excitement, aggressivess, madness then paralysis & death.
Define catecholamines and give examples.
Catecholamines are neurotransmitters that are synthesized from tyrosine. Norepinephrine, dopamine, and epinephrine.
Name 2 inhibitory transmitters.Describe what they do and their amount.
GABBA and glycine., they open Cl channels. 1/2 of inhibitory synapse is glycine, 1/2 Gaba.
Define neuropeptides, where they are found, what their purpose is.
3 to 40 amino acids linked by peptide bonds. Prevalent in both CNS and PNS. Can be inhibitory or exitatory, can serve as NTs or hormones.
Define enkephalins.
A neuropeptide that cause a potent analgesic effect 200 times stronger than morphine.
Name 3 opoid peptides and what they do.
Enkephalins, endorphins, dynorphins. They produce analgesic effects by binding to opoid recpetors.
Define Substance P and its purpose.
Its released by neurons that transmit pain related input & enhances perception of pain. Enkephalin & endorphons suppress release of substance P.
Define a spinal tap, and its purpose. Where is it given and why?
AKA lumbar puncture is when a needle is inserted into the subarachnoid space. It is used to withdraw CSF, give antibiotics or anesthetic, measure pressure or evaluate. It is given between L3 & L4 OR L4 &L5 because it provides safe access to the subarachnoid space w/out damaging spinal cord.
Define menginges, name the 3 spinal meninges and their corresponding spaces in order from most to least superficial.
Meninges are 3 connective tissue coverings that encircle spinal cord and brain. Therr are spinal meninges that continue into cranial meniges. 3 spinal menginges:
vetebral canal
Dura Mater
Epidural space
arachnoid mater
subdural space
pia mater
arachnoid space
Severing at this spot on the spinal cord causes respiratory arrest/
Above the origin of the phrenic nerves. C3, C4, C5 because the phrenic nerves can no longer send impulses to the diaphragm.
The cause of Erb Duchenne palsy, the injury, and the presentation.
Injury to the roots of the brachial plexus (c5, c6) from forceful pulling away of the head from the shoulder - heavy fall or excessive stretching (like childbirth). Presents as adducted shoulder. (waiters tip) loss of sensation along lateral side of arm.
Radial nerve injury, brachial plexus
cause: improper injection into deltiod, tight cast, presents as wrist drop.
Median nerve injury - brachial plexus
Median nerve palsy, numbness tingling, pain in palm +finders. inability to flex interphalaneal joints, weak wrist flexion.
Ulnar nerve injury- brachial plexus
ulnar nerve palsy, inability to abduct/adduct fingers, clawhand, loss of sensation over little finger.
Long thoracic nerve injury- brachial plexus
paralysis of serratus anteria muscles. Scapula protrudes, looks like wing. (winged scapula)
Femoral nerve injury - lumbar plexus
Largest nerve, injury occurs with stab or gunshot, cant extend leg, loss of sensation in thigh.
Obtruator nerve uninjury - lumbar
paralysis of the adductor muscles of the thig, loss of sensation in thigh, can happen from nerve pressure by fetal head in pregnancy.
What is the most common cause of back pain?
Compression of the sciatic nerve
compression or irritation of sciatic nerve, pain extend down buttock posterior/lateral aspect of leg and foot. Cause: slipped disc, disloc hip, osteoarthritis, pregnancy uterine pressure, inflammation, irritation or improperly administered injection (gluteal)
This is the longest nerve in the human body.
Sciatic nerve.
Define dermatone.
The area of the skin that provides sensory input to the CNS via one pair of spinal nerves or the trigeminal (V) nerve.
Why is it important to know which spinal cord segments supply each dermatone?
To locate damaged regions of the spinal cord via assessing altered sensation in the dermatone.
Explain dermatone overlap.
Some dermatones overlap, therefore if one area is damaged there may be little loss of sensation. Also during anesthesia adjacent spinal nerves must be blocked to provide adequate pain relief.
Patellar reflex
Knee jerk - reflex is blocked by damage to sensory or motor nerves on 2nd 3rd or 4th lumbar segments in spinal cord. Often absent with diabetes mellitus or neurosyphillis.
Achilles reflex
ankle jerk - Absence indicates damage to nerves supplying posterior leg mucles or lumbosacral region of spinal cord. may dissapear in CDM, neurosyphillis, alcholism, subarach hemorrhages. Exagerrated = cervical cord compression on 1st or 2nd sacral segment.
Babinski Sign
Gentle stroking on lateral out margin of sole. Great tow dorsiflexes, with or without fanning. Natural in children under 18 mos, is due to incomplete myelination. Positive over 18 mos = abnormal, shows lesion or interruption of corticospinal tract.
Normal response is Negative Babinski, curling of all the toes.
Abdominal reflex
Contraction of muscles on abdominal wall in response to stroking the side, unbilicus moves in direction of stimulus. Absense = lesion of corticospinal tract, lesion on peripheral nerves, MS.
Pupillary light reflex
Pupils of both eyes decrease in diameter when either eye is exposed to light. Absence = Brain damage or injury.
Phantom limb sensation
People with liimb aputaed who still experience sensations such as itching, pressure, tingling, & pain in absent limb.
1. cerebral cortex interperts impulses rising from sensory neurons that previously carried info from absent limb or 2) Neurons in brain generate sensation of body awareness.
Recpetors for pain, speed types of pain.
Nocioceptors, free nerve neding in every tissue except brain.
1. Fast pain - Rapidly after stimulus is applied acute or sharp not felt in deeper tissues.
2. Slow - Begins a second or more after stimulus, intensity gradually increases, small unmyelinated fibers. Toothache.
Types of pain with regard to receptors.
Superficial somatic pain - stimulation at skin
Deep somatic pain - receptors in skeletal muscles, joins, tendons.
Visceral pain - receptors in visceral organs.