Physiology Chapter 8

The ion necessary to initiate the release of acetylcholine into the synaptic cleft is

Calcium

Microglia are found in the

Central Nervous System

Oligodendrocytes are found in the

Central Nervous System

The brain and spinal cord together form the :

Central Nervous System

An increased threshold is associated with the _______ refractory period

Absolute

Information coming into the central nervous system is transmitted along ______________ neurons

Afferent and Sensory Neurons

The multiple thin branched structures on a neuron whose main function is to receive incoming signals are the

Dendrites

An excitatory postsynaptic potential (EPSP)

Depolarizes a neuron, increasing the likelihood of an action potential

The enteric nervous system is a network of neurons that function in controlling

Digestion

During the relative refractory period ________ gates are open

Sodium Potassium

The channelopathy known as QT syndrome, is a result of mutation in __________ channels

Sodium Potassium Calcium

Choose all the items that are incorrectly matched Activation Gate - Closed at rest Inactivation Gate -Open at rest Inactivation Gate -Opens during repolarization Activation Gate -opens during depolarization

They all are incorrectly matched

Which of the following is the location where action potentials originate

Trigger Zone

Temporal Summation refers to

additional graded potentials arriving before previous ones have ceased

The all - or - none principle states that

all stimuli great enough to bring the membrane to threshold will produce action potentials of identical magnitude

Which is NOT a neuroeffector junction? The junction between a neuron and a(n)

neuron

During childhood, growth and development of the brain PRIMARILY occurs by increasing

neuron size number of dendrites and synapses

A damaged neuron has a better chance of survival and repair if the __________ is/are undamaged

cell body

Which of the following is NOT a known drug effect on synaptic function

change the type of neurotransmitter found in the synaptic vesicle

Ion channel inactivation is

closing of the channel even when the stimulus continues.

The pattern of synaptic connectivity where a large number of presynaptic neurons provide input to a single postsynaptic neuron, is known as

convergence.

Voltage regulated channels are located

in membranes of axons

Interneurons are found

only in the CNS

The rearrangement of connections at synapses, which occurs throughout life, is termed

plasticity

The sodium-potassium exchange pump

requires ATP for energy

Inhibitory postsynaptic potential (IPSPs)

result in local hyperpolarizations

To increase the amount of neurotransmitter released onto a postsynaptic cell, the presynaptic cell would have to

send action potentials with higher frequency

Calcium is important in the synapse because it

signals the exocytosis of the neurotransmitter

The Nernst equation predicts

the membrane potential resulting from permeability to a single ion

What does the Goldman-Hodgkin-Katz equation take into account that the Nernst equation does NOT ?

the permeabilities of the ions

The total amount of neurotransmitter released at the axon terminal is directly related to

the total number of action potentials

The absolute refractory period of an action potential

Ensures one way travel down an axon Allows a neuron to ignore a second signal send that closely follows the first Prevents summation of action potentials

When voltage gated Na+ channels of a resting neuron open

Na + enters the neuron The neuron depolarizes

Excitatory neurotransmitters of the CNS usually act by opening ________ channels

Na+

The rising phase of the action potential is due to

Na+ flow into the cell

The collection of axons that carries information between the central nervous system and the peripheral effectors is called the

Nerve

Ependymal cells are found in the

Peripheral Nervous System

Satelite Cells are found in the

Peripheral Nervous System

Schwann Cells are found in the

Peripheral Nervous System

The afferent and efferent axons together form the :

Peripheral Nervous System

Which ion(s) is/are higher in concentration inside the cell compared to outside

Potassium

The term hyperkalemia specifically indicated too much potassium in which fluid compartment

Blood

The cell body of neurons is generally

10% of the volume

What is the correctly written Nernst equation

61/z x log [ion] out / [ion] in

When two or more graded potentials arrive at the trigger zone, which of the following could happen?

An excitatory and inhibitory signal can cancel each other out Two excitatory stimuli may be additive and summation could occur Two inhibitory stimuli may be additibe resulting in lower excitability

Exocrine glands, smooth muscles and cardiac muscles are controlled by the

Autonomic Nervous System

The structure on the neuron that transmits electrical signals to trigger the release of neurotransmitter is the

Axon

The axon is connected to the cell body by the

Axon Hillock

A chemical synpase ALWAYS includes ________

Axon Terminal Presynaptic Cell Synaptic Cleft Postsynaptic Cell

Neurotransmitters are released from the

Axon Terminals

Neurotransmitter is stored and released from:

Axon Terminals and Axon Varicosities

Action potentials occur in the membrane of

Axons

Some neurotoxins work essentually the same way as local anaesthetics, which is to

Bind to Na+ channels and inactivate them Prevent Depolarization by blocking Na+ entry into the cell

Which type of synpase is most prevalent in the nervous system

Chemical

Glial Cells communicate primarily using

Chemical Signals

In the membrane of a resting nerve cell, when chemically gated Cl- channels open

Cl- ions enter the cell

Inhibitory neurotransmitters of the CNS act by opening __________ channels

Cl- or K+

Branches that sometimes occur along the length of an axon are called

Collaterals

Once the action potential reaches the axon terminal, what happens next?

Exocytosis of neurocrine Release of the NT into the synaptic cleft Release of a neurohormone into the blood

Detailed understanding of the cellular basis of signalig in the nerbous system has lead to good understanding of consciousness, intelligence and emotion. True or False?

FALSE

In order for a synpase to be an effective means of cellular communication, slow removal or inactivation of neurotransmitter molecules from the synapse is important. T or F

FALSE

Anterograde and Retrograde axonal transport are forms of ___________ transport

Fast

Which is /are the most common inhibitory neurotransmitters of the CNS

GABA Glycine

Clusters of nerve cell bodies in the peripheral nervous system are called

Ganglia

The neurotransmitter thought to be involved in learning and memory is

Glutamate

The tip of an embryonic nerve cell's axon is called a

Growth Cone

Identify the false statement

IPSPs depolarize the membrane

Which of the following will increase the conduction rate of action potentials?

Increase the diameter of the axon , increase the resistance of the axon membrane to ion leakage

Graded Potentials may

Initiate action potential Depolarize the membrane to threshold voltage Hyperpolarize the membrane be called EPSPs or IPSPs

Once the stimulus alters the receptor in the cell's membrane what happens next?

Ion channels open, allowing ions to enter or exit The membrane permeability is altered The second messenger is activated on the inside of the cell

The falling phase of the action potential is due primarily to

K+ flow out of the cell

The major determinant of the resting potential of all cells is

K+ gradient between the blood and interstitial fluid

When vvoltage gated K + channels of a resting neuron open

K+ leaves the neuron

These glial cells act as scavengers

Microglia

These glial cells may contribute to Lou Gehrigs Disease

Microglia

In order to signal a stronger stimulus, action potentials become

More frequent

In general the nervous system is composed of what two types of cells

Neurons and Glial Cells

If hyperpolarizing graded potentual and a depolarizing graded potential of similiar magnitudes arrive at the trigger zone at the same time, what happens?

Nothing, they will cancel each other out

In response to binding a neurotransmitter, a postsynaptic cell can

Open chemically gated ion channels, causing graded potentials known as fast synaptic potentials Close ion channels via G proteins and second messenger systems, producing slow responses Regulate protein synthesis and affect the metabolic activities in the post-synaptic cell

The point during an action potential when the inside of the cell has become more positive than the outside is known as

Overshoot

The portions of a neuron that extend off the roughly spherical cell body are collectively called:

Processes

Glial Cells

Provide structural and metabolic support Guide neurons during growth and repair Help maintain homeostasis of the brains extracellular fluid

Myelin is formed by

Schwann Cells Oligodendrocytes

Repair of damaged neurons can be assisted by certain neurotrophic factors secreted by the

Schwann cells

Autonomic motor neurons are subdivided into the:

Sympathetic and Parasympathetic Divisions

The region where the axon terminal meets its target cell is called the:

Synapse

When a second EPSP arrives at a single synapse before the effects of the first have disappeared, what occurs?

Temporal Summation

The resting membrane potential results from

Uneven distribution of ions across the cell membrane Differences in membrane permeability to Na + and K +

Ion concentrations are first significantly affected after _________action potentials

a few thousand

Presynaptic Facilitation makes a pathway

more likely to be in use through depolarization of selected neurons capable of alternation through training and conditioning

Spatial Summation refers to

multiple graded potentials arriving at one location simultaneously

All of the following must occur before a second action potential can begin, EXCEPT

the NA+ and K+ ions that moved in/out of the cell must move back to their original position

Which of the following does NOT influence the time necessary for a nerbe impulse to be conveyed by a particular neuron

whether axon is sensory or motor

The site of information integration in the nervous system is the

trigger zone

The term axonal transport refers to

vesicle transport of proteins and organelles down the acon

Postsynaptic Integration

when multiple, possibly even conflicting signals reach a neuron the neuron evaluates the signals and may respond or not.