Nervous System Study Guide

Front 1

A nerve impulse is also known as this.

Back 1

Action Potential

Front 2

These 2 systems are responsible for maintaining homeostasis.

Back 2

Nervous & Endocrine

Front 3

The 4 things the nervous system is responsible for.

Back 3

Perceptions, behaivors, memories, voluntary movements.

Front 4

Define "nerve".

Back 4

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.

Front 5

Define ganglia.

Back 5

A group of neuronal cell bodies outside of the CNS.

Front 6

Identify the 3 basic functions of the nervous system and expain their types.

Back 6

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.

Front 7

How many neurons are in the brain?

Back 7

100 billion

Front 8

The 2 types of cells that make up nervous tissue and their functions.

Back 8

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.

Front 9

Define stimulus.

Back 9

Any change in the enviornment strong enough to generate an action potential.

Front 10

Define action potential.

Back 10

AKA nerve impulse, and electrical signal that propagates along the surface of the membrane of a neuron.

Front 11

Explain the size and speed of neurons.

Back 11

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.

Front 12

3 parts of a neuron.

Back 12

1. Cell body
2, Axon
3. Dendrites

Front 13

Define axon terminal.

Back 13

Where the axon & its collateral end in many proccesses.

Front 14

Define synapse.

Back 14

The site of communication between two neurons or between a neuron and an effector cell.

Front 15

The tips of axon terminals swell at these structures.

Back 15

Synaptic end bulb.

Front 16

Define synaptic vescicle.

Back 16

A membrane enclosed sac a the synaptic end bulb that stores a neurotransmitter.

Front 17

What is the function of a neurotransmitter?

Back 17

To excite or inhibit other neurons, muscle fibers, or gland celss.

Front 18

Name the 3 functional types of neurons.

Back 18

1. Sensory/afferent
2. Motor/efferent
3. Interneurons/Association

Front 19

Define sensory neuron.

Back 19

Carries information to the CNS.

Front 20

Define Motor neuron.

Back 20

Carries information away from the CNS to an effector.

Front 21

Define interneuron.

Back 21

AKA association neuron, process information and elicits a motor response.

Front 22

Define neuroglia and their purpose.

Back 22

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.

Front 23

What are brain tumors derived from glia called, & why are they highly malignant?

Back 23

Gliomas, they are highly malignant because they grow rapidly (due to glia multiplying rapidly)

Front 24

The 4 types of neuroglia in the CNS & state their functions.

Back 24

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.

Front 25

The 2 types of glial cells in the PNS & their functions.

Back 25

1. Schwann cells - encircle PNS axons, myelinate.

2. Satellite cells - Structural support & regulation of exchanges between neuronal cells & fluid.

Front 26

What is the difference between a Schwann cell and a oligodendrocyte?

Back 26

Oligodendrocyte
a) In the CNS b) Myelinates several axons

Schwann Cell
a) In the PNS B) myelinates single axon c) participate in axon regeneration

Front 27

Define myelination, unmyelation, demyelation

Back 27

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.

Front 28

Why are an infant;s responses to stimuli less rapid & coordinated than an older child's?

Back 28

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.

Front 29

Define nodes of ranvier.

Back 29

Gaps in the myelin sheath, which allow nerve impulses to travel via jumping from node to node.

Front 30

Define membrane potential.

Back 30

An electrical potential difference (voltage) across the plasma membrane of excitable cells.

Front 31

Electrochemical gradient.

Back 31

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.

Front 32

Name the four types of ion channels.

Back 32

1. Leakage channels
2. Ligand-gated channel
3. Mechanically gated
4. Voltage gated

Front 33

Define leakage channel.

Back 33

An ion channel with gates that randomlly alternate between open & closed.

Front 34

What ion is a membrane more permeable to and why?

Back 34

More permeable to potassium (k+) than sodium (Na) because plasma membranes have many more k+ channels that leak more.

Front 35

Define a ligund gated channel and describe what might open it.

Back 35

opens and closes in response to a specific chemical stimulus such as NTs, hormones, ions.

Front 36

Define a mechanically gated channel and describe what might open it.

Back 36

Open and closes in response to mechanical stimulation such as touch, pressure, tissue stretching. Example: Auditory receptors in ear.

Front 37

Describe a voltage gated channel and what its main purpose it.

Back 37

Opens in response to a change in membrane potential (voltage). They participate in generation & conduction of action potentials.

Front 38

What is the typical resting membrane potential?

Back 38

-70

Front 39

Explaint the "All or nothing" theory.

Back 39

Stimulus must have the capacity to change the membrane potential to threshold in order to cause a reaction.

Front 40

What is the threshold?

Back 40

-55, the point to which a stimulus must change the membrane potention in order to cause a reaction.

Front 41

What is depolarization?

Back 41

The negative membrane potential becomes more positive, peaks at -30.

Front 42

What is repolarization?

Back 42

The membrane potential is returned to the resting membrane potention by becoming more and more negative.

Front 43

What is the refractory period?

Back 43

mV is too low for a stimulus to reach the threshold. Cannot generate another action potential. (Anesthesia causes this).

Front 44

What is hyperpolarization?

Back 44

The stage following repolarization in which the membrane potential becomes more negative than the resting potential. Goes to about -90.

Front 45

Explain the difference between continous and saltatory conduction.

Back 45

Continous - unmyelinated axons, slower, opens channels in succession.

Saltatory - myelinaetd, faster, impulse jumpes from node to node due to many voltage channels.

Front 46

Name 3 things that affect the speed of propagation and describe them.

Back 46

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!

Front 47

Define EPSP and explain what it does to the membrane threshold.

Back 47

Exictatory postsynaptic potential - Depolarizes the membrane, bringing it closer to the threshold therefore exitactory.

Front 48

Define IPSP and explain what it does to the membrane potential.

Back 48

Ihibitory postsynaptic membrane - hyperpolarizes membrane, bringing it farther from threshold, therefore inhibitory.

Front 49

Why does the same neurotransmitter work differently at different synapses?

Back 49

It can be excitatory or inhibitory depending on what receptor it binds to, and which channel it ulitmatley opens.

Front 50

Explain 3 things that may happen to NT's after a reaction.

Back 50

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)

Front 51

Define Multiple Sclerosis.

Back 51

Autoimmune disease that causes progressive destruction of myelin sheaths surrounding the neurons in the CNS.

Front 52

Define Epilepsy

Back 52

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.

Front 53

Gullian Barre Syndrome

Back 53

Demylination occuring from macrophages stripping away myelin from axons in PNS. Causes paralysis.

Front 54

Neuroblastoma.

Back 54

Malignant tumor consisting of immature nerve cells (neuroblasts), rare. Most common tumor in infants.

Front 55

Neuropathy

Back 55

Any disorder that affects nervous sytem, cranial & spinal such as Bell's Palsy.

Front 56

Rabies

Back 56

Fatal diease by a virus that reaches CNS vis axonal transport. Bite from infected animal. Excitement, aggressivess, madness then paralysis & death.

Front 57

Define catecholamines and give examples.

Back 57

Catecholamines are neurotransmitters that are synthesized from tyrosine. Norepinephrine, dopamine, and epinephrine.

Front 58

Name 2 inhibitory transmitters.Describe what they do and their amount.

Back 58

GABBA and glycine., they open Cl channels. 1/2 of inhibitory synapse is glycine, 1/2 Gaba.

Front 59

Define neuropeptides, where they are found, what their purpose is.

Back 59

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.

Front 60

Define enkephalins.

Back 60

A neuropeptide that cause a potent analgesic effect 200 times stronger than morphine.

Front 61

Name 3 opoid peptides and what they do.

Back 61

Enkephalins, endorphins, dynorphins. They produce analgesic effects by binding to opoid recpetors.

Front 62

Define Substance P and its purpose.

Back 62

Its released by neurons that transmit pain related input & enhances perception of pain. Enkephalin & endorphons suppress release of substance P.

Front 63

Define a spinal tap, and its purpose. Where is it given and why?

Back 63

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.

Front 64

Define menginges, name the 3 spinal meninges and their corresponding spaces in order from most to least superficial.

Back 64

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

Front 65

Severing at this spot on the spinal cord causes respiratory arrest/

Back 65

Above the origin of the phrenic nerves. C3, C4, C5 because the phrenic nerves can no longer send impulses to the diaphragm.

Front 66

The cause of Erb Duchenne palsy, the injury, and the presentation.

Back 66

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.

Front 67

Radial nerve injury, brachial plexus

Back 67

cause: improper injection into deltiod, tight cast, presents as wrist drop.

Front 68

Median nerve injury - brachial plexus

Back 68

Median nerve palsy, numbness tingling, pain in palm +finders. inability to flex interphalaneal joints, weak wrist flexion.

Front 69

Ulnar nerve injury- brachial plexus

Back 69

ulnar nerve palsy, inability to abduct/adduct fingers, clawhand, loss of sensation over little finger.

Front 70

Long thoracic nerve injury- brachial plexus

Back 70

paralysis of serratus anteria muscles. Scapula protrudes, looks like wing. (winged scapula)

Front 71

Femoral nerve injury - lumbar plexus

Back 71

Largest nerve, injury occurs with stab or gunshot, cant extend leg, loss of sensation in thigh.

Front 72

Obtruator nerve uninjury - lumbar

Back 72

paralysis of the adductor muscles of the thig, loss of sensation in thigh, can happen from nerve pressure by fetal head in pregnancy.

Front 73

What is the most common cause of back pain?

Back 73

Compression of the sciatic nerve

Front 74

Sciatica

Back 74

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)

Front 75

This is the longest nerve in the human body.

Back 75

Sciatic nerve.

Front 76

Define dermatone.

Back 76

The area of the skin that provides sensory input to the CNS via one pair of spinal nerves or the trigeminal (V) nerve.

Front 77

Why is it important to know which spinal cord segments supply each dermatone?

Back 77

To locate damaged regions of the spinal cord via assessing altered sensation in the dermatone.

Front 78

Explain dermatone overlap.

Back 78

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.

Front 79

Patellar reflex

Back 79

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.

Front 80

Achilles reflex

Back 80

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.

Front 81

Babinski Sign

Back 81

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.

Front 82

Abdominal reflex

Back 82

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.

Front 83

Pupillary light reflex

Back 83

Pupils of both eyes decrease in diameter when either eye is exposed to light. Absence = Brain damage or injury.

Front 84

Phantom limb sensation

Back 84

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.

Front 85

Recpetors for pain, speed types of pain.

Back 85

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.

Front 86

Types of pain with regard to receptors.

Back 86

Superficial somatic pain - stimulation at skin
Deep somatic pain - receptors in skeletal muscles, joins, tendons.
Visceral pain - receptors in visceral organs.