A+P

Question 1

Which 2 questions does the clinician attempt to ask when trying to identify which part of the nervous system is affected?

Answer 1

1. Where is (are) the lesions?

2. What is (are) the lesions?

Question 2

The nervous system is constructed under a ________ manner.

Answer 2

modular

Question 3

Different part of the nervous system ______ different functions.

Answer 3

subserve

In turn, in many parts of the brain or spinal cord, even relatively small well-circumscribed lesions produce loss or severe impairment of a specific function. This effect reflects the principle of localized function within the nervous system.

Question 4

Unipolar (pseudo-unipolar) neurons possess one axon that divides into two long ______; usually sensory neurons.

Answer 4

processes

Question 5

Bipolar neurons possess one axon and one _____; rare, but found in the retina and _____ epithelium.

Answer 5

dendrite
olfactory

least common

Question 6

Multipolar neurons possess one axon and _____ or more dendrites; most common.

Answer 6

two

Question 7

In efferent neurons, there is a ______ process closer to the CNS coming from the cell body and on the other side of the cell body there is a _______ process that is responsible for sending signals to target tissues.

Answer 7

central
peripheral

The peripheral process conducts action potentials from the dendrites to the cell body, where they pass directly to the central process.

Question 8

The ______ and ______ dendrites together with the cell body are the input elements of the neuron, receiving signals from other neurons.

Answer 8

apical

basal

Question 9

The cell body is also called the _____ and is the metabolic center of the cell.

Answer 9

soma

It includes the nucleus (genes), ER.

Question 10

The cell body usually gives rise to two kinds of processes; several _____ dendrites and one ____ tubular axon.

Answer 10

short

long

Question 11

______ are the main apparatus for receiving incoming signals from other nerve cells.

Answer 11

Dendrites

Question 12

The _____ typically extends some distance from the cell body before it branches, allowing it to carry signals to many target neurons.

Answer 12

axon

Can convey signals from 0.1 mm - 1m

Question 13

________ from a neuron are initiated at a specialized trigger region near the origin of the axon called the initial segment from which the action potentials propagate down the axon without failure or distortion speeds of 1-100 m/s.

Answer 13

Action potentials

The amplitude do the AP remains constant at 100 mV because the action potential is an all or none impulse that is regenerated at regular intervals along the axon.

Question 14

Action potentials are the ______ by which the brain receives, analyzes, and conveys information.

Answer 14

signals

Question 15

The type of information conveyed by an action potential is determined not by the form of the signal but by the ______ the signal travels to the brain

Answer 15

pathway

Question 16

The myelin sheath that wraps around large axons is meant to ______ speed by insulating the axon to create better conduction.

Answer 16

Increase

Question 17

The name of the intervals that interrupt the myelin sheath is called the ____ __ ______, which are uninsulated spots on the axon where the action potential is regenerated.

Answer 17

the nodes of Ranvier.

Question 18

Near its end, the axon divides into fine branches that contact other neurons at specialized zones of communication known as _______.

Answer 18

synapses

Question 19

The presynaptic cell transmits signals from specialized enlarged regions of its axon’s branches, called presynaptic ______.

Answer 19

terminals

aka nerve terminals

Question 20

The presynaptic and postsynaptic cells are separated by a very narrow space called the ____ _____.

Answer 20

synaptic cleft.

Question 21

Some presynaptic neurons excite their postsynaptic target cells.

Other presynaptic neurons _____ their target cells.

Answer 21

inhibit

Question 22

Each neuron is a discrete cell with distinctive processes arising from its cells body and that neurons are signaling units of the nervous system. This is known as the _____ ____.

Answer 22

neuron doctrine

Question 23

1. Principal of dynamic polarization - one direction travel
2. Connectional specificity

Ramon y Cajal

Answer 23

1. States that electrical signals within a nerve cell flow in only one direction: from the postsynaptic sites of the neuron (dendrites and cell body) to the trigger region at the axon. Then the AP is propagated along the entire length of the axon to its terminals.
2. Nerve cells do not connect randomly with one another in the formation of networks but make specific connections - at particular contact points - with certain postsynaptic target cells and not with others.

Question 24

The feature that most distinguishes one type of neuron from another is _____, specifically the number of the processes arising from the cell body.

Answer 24

form

Question 25

Unipolar neurons are the simplest because they have a _____ primary process, which usually gives rise to many branches.

Answer 25

single One branch serves as the axon; other branches function as receiving structures; other branches function as the receiving structures. These cells predominate in the nervous system of invertebrates. In vertebrates, they occur in the ANS.

Question 26

Unipolar neurons are the simplest because they have a _____ primary process, which usually gives rise to many branches. Pseudo-unipolar cells are called so because they began as ____ cells but the 2 cells processes fused into a single continuous structure that emerges from a single point in the cell body, and the dendrite is endowed with the specializations that render it an axon. One axon transmits information from the sensory receptors in the skin, joints, and muscle towards the cell body, while the other carries the sensory information to the spinal cord.

Answer 26

single bipolar One branch serves as the axon; other branches function as receiving structures; other branches function as the receiving structures. These cells predominate in the nervous system of invertebrates. In vertebrates, they occur in the ANS.

Question 27

Bipolar neurons have an oval soma that gives rise to ___ distinct processes; a dendritic structure that receives signals from other neurons and an axon that carries information toward the CNS.

Answer 27

two Many sensory cells are bipolar. Retina & olfactory

Question 28

These neurons carry information from the body's peripheral sensors into the nervous system for the purpose of both perception and motor coordination.

Answer 28

Sensory neurons Some are called afferent Including neurons in primary and secondary cortical areas that respond to changes in a sensory feature such as displacement of an object in space, a shift in sound frequency, or the angular rotation of the head or even something as complex as the face.

Question 29

These neurons typically have a single axon and many dendritic structures emerging from various points around the cell body. They vary in shape, especially the _____ of their axons, and in their extent, dimensions, and intricacy of their dendritic branching.

Answer 29

length Usually the branching correlates with the number of synaptic contacts that other neurons make onto them.

Question 30

______ _______ carry commands from the brain or spinal cord to muscles and glands and known as efferent neurons.

Answer 30

Motor neurons This can also include other neurons that do not innervate the muscle directly but that command action indirectly. A useful characterization of motor and sensory neurons alike is their temporal fidelity to matters outside the nervous system.

Question 31

Interneurons comprise the most numerous functional category and are subdivided into two classes; _____ and _____.

Answer 31

relay | local

Question 32

Relay or ________ interneurons have long axons and convey signals over considerable distances, from one brain region to another.

Answer 32

projection

Question 33

Local interneurons have _____ axons because they form connections with nearby neurons in local circuits.

Answer 33

short

Question 34

There are 2 to 10 times more ____ than neurons in the vertebrate CNS.

Answer 34

glia

Question 35

Glia surround the cell bodies, axons, and dendrites of neurons and they do not form dendrites and axons. They also function differently.

Answer 35

Even though they arise from the same embryonic precursor cells, they do not have the same membrane properties as neurons and thus are not electrically excitable. Hence they are not directly involved in electrical signaling like nerve cells.

Question 36

____ play a role in allowing electrical signals to move quickly along the axons of neurons and they appear to play an important role in guiding connectivity during early development and stabilizing new or altered connections between neurons that occur through learning.

Answer 36

Glia Over the past decade, interest in the diverse functions of glia has accelerated and their characterization has changed from support cells to functional partners of neurons.

Question 37

____ play a role in allowing electrical signals to move quickly along the axons of neurons and they appear to play an important role in guiding connectivity during early development and stabilizing new or altered connections between neurons that occur through learning.

Answer 37

Glia Over the past decade, interest in the diverse functions of glia has accelerated and their characterization has changed from support cells to functional partners of neurons.

Question 38

Action potential by neuron is when threshold is reached and then Na+ goes into neuron to depolarize and K+ goes out to repolarize.

Answer 38

There is a relative refractory period followed by a resting state. - Absolute refractory period is between depolarization and repolarization. - Relative refractory period is after repolarization begins.

Question 39

Action potentials are conducted 50x faster in myelinated axons compared to unmyelinated neurons and this faster propagation is known as _____ ________.

Answer 39

saltatory conduction

Question 40

If ____ cells divide uncontrollably they can become cancerous and form intracranial tumors known as ______, including astrocytomas, ______, and ______.

Answer 40

``` glia gliomas (astrocytomas - glioblastoma multiforme - most aggressive type) oligodendrogliomas ependymomas ```

Question 41

______ for the BLOOD BRAIN BARRIER

Answer 41

Astrocytes

Question 42

______ are neurological "scavengers" or resident macrophages.

Answer 42

Microglia

Question 43

________ ________ synthesize CSF. They line the CSF-filled ventricles in the brain and the central canal of the spinal cord.

Answer 43

Ependymal cells (Ependymocytes)

Question 44

Every behavior is mediated by specific sets of interconnected neurons. Every neuron's behavioral function is determined by its connections with other neurons.

Answer 44

Example of this is the knee jerk reflext

Question 45

The pattern of connection, in which 1 neuron activates many target cells is called ________.

Answer 45

divergence It is especially common in the input stages of the nervous system; by distributing its signals to many target cells, a single neuron can exert wide diverse influence.

Question 46

A single motor neuron like in the knee jerk circuit receives 200-450 input contacts from appropriately 130 sensory cells and this is called _______.

Answer 46

convergence It is common at the output stages of the nervous system; a target motor cell that receives information from many sensory neurons is able to integrate information from many sources. Each sensory neuron input produces a relatively weak excitation, so convergence also ensure that a motor neuron is activated only when a sufficient number of sensory neurons are activated together.

Question 47

_______ ________ enhances the effect of the active pathway by suppressing the activity of pathways mediating opposing actions.

Answer 47

Feedforward inhibition It is common in monosynaptic reflex systems. Ex. knee jerk reflex circuit - afferent neurons from extensor muscles excite the extensor motor neurons and the inhibitory interneurons that prevent firing of the motor cells innervating the opposing flexor muscles.

Question 48

_____ ______ is a self regulating mechanism. Here extensor motor neurons act on inhibitory interneurons that in turn act on the extensor motor neurons themselves and reduce their probability of firing.

Answer 48

Feedback inhibition The effect is to dampen activity within the stimulated pathway and prevent it from exceeding a certain critical level. Some circuits have feedback inhibition

Question 49

Tp produce a behavior (ex. stretch reflex), each participating sensory and motor nerve cell must generate 4 different signals in sequence, each at a different site in the cell.

Answer 49

1. receptive component for producing graded input signals 2. a summing or integrative component that produces a trigger signal 3. a conducting long range signaling component that produces all or none conducting signals. 4. a synaptic component that produces output signals to the next neuron in line or to muscle or gland cells.

Question 50

The input, integrative, and conductive signals are all electrical and integral to the cell. The output signal is a chemical substance ejected by the cell into the synaptic cleft.

Answer 50

The model neuron Not all neurons share all 4 of these features.

Question 51

The different types of signals generated in a neuron are determined in part by the _______ properties of the cell membrane.

Answer 51

electrical

Question 52

In a typical resting neuron the voltage on the inside is more _____ than the outside of the cell.

Answer 52

negative The voltage on outside of cell is 0.

Question 53

The extracellular concentrations of Na+K+ are maintained by the kidneys and the ______ cells.

Answer 53

astroglial - aka astrocytes

Question 54

In local signals, a ionic current changes the membrane potential, producing a local signal called the ______ ______.

Answer 54

receptor potential The amplitude and duration of a receptor potential depend on the intensity of the muscle stretch, for ex. The larger or longer lasting the stretch, the larger or longer lasting is the resulting receptor potential. Most receptor potentials are depolarizing Hyperpolarizing (inhibitory) ones are found in the retina

Question 55

The distance of depolarization travels shorter if the diameter of the axon is ______ and longer if the diameter is ______. Also shorter if _______ can pass easily through the membrane and longer if the membrane is insulated with myelin.

Answer 55

smaller larger current

Question 56

The ensuing flow of current that alters the membrane potential of the cell from opening of ion channels in the postsynaptic neuron after the neurotransmitter is release from the presynaptic neuron into the cleft is called the _______ _______.

Answer 56

synaptic potential In this example knee jerk reflex The synaptic potential is graded like the receptor potential. -its amplitude depends on how much transmitter is released. This potential can be depolarizing or hyperpolarizing depending on which receptor is activated.

Question 57

The initial segment of the axon has the highest density of voltage-sensitive Na+ channels and therefore the lowest threshold for generating an ____ _____. This part of the axon is known as the _____ _____.

Answer 57

action potential This is why an input signal spreading passively along the cell membrane is more likely to give rise to an AP at the initial segment of the axon that at other sites in the cell. trigger zone

Question 58

The initial segment of the axon has the highest density of voltage-sensitive Na+ channels and therefore the lowest threshold for generating an ____ _____. This part of the axon is known as the _____ _____.

Answer 58

action potential This is why an input signal spreading passively along the cell membrane is more likely to give rise to an AP at the initial segment of the axon that at other sites in the cell. trigger zone -here the sum of the activity of all receptor potentials is summed and where, if the sum of the input signal reaches threshold, the neuron generates an AP.

Question 59

The AP is ____ or ____.

Answer 59

all none below threshold dont produce signals and above threshold all produce signals of the same amplitude. Also holds true for regenerated AP at the nodes of Ranvier

Question 60

Some neurons are active in the absence of stimuli.

Answer 60

Spontaneous active nerve cells (beating neurons) fire action potentials regularly. Others (bursting neurons) fire brief bursts of action potentials.

Question 61

How is information conveyed to distinguish recognition of an object vs pain from that object?

Answer 61

Interconnected neurons form anatomically and functionally distinct pathwayways - labeled lines -

Question 62

How is information conveyed to distinguish recognition of an object vs pain from that object?

Answer 62

Interconnected neurons form anatomically and functionally distinct pathways - labeled lines - and it is these pathways of connected neurons, these labeled lines, not individual lines, that convey information. The neural pathways activated by receptor cells in the retina that respond to light are completely distinct from the pathways activated by sensory cells in the skin that respond to touch.

Question 63

Neurotransmitters are held in sub cellular organelles called _____ ______ and released at sites called ____ ______.

Answer 63

synaptic vessels active zones The output signal is graded to the amount of neurotransmitter released, which is determined by the number and frequency of the AP's that reach the presynaptic terminals. After binding a synaptic potential is generated which has excitatory or inhibitory effects depending on the post synaptic receptor not the neurotransmitter. The same transmitter can have different effects depending on the postsynaptic receptor.