Chapter 12: Nervous Tissue LearnSmart

Which of the following segments of a neuron contain large numbers of voltage gated potassium channels and voltage gated sodium channels

-Conductive segment -Initial segment

The nervous tissue of a young adult may contain up to ____ glial cells

1 triliion

Place the events of synaptic transmission from earliest to latest

1. Action potential reaches synaptic knob 2. Voltage gated calcium channels open 3. Calcium enters the synaptic knob 4. Calcium triggers exocytosis of vesicles 5. Neurotransmitter diffuses across synaptic cleft 6. Neurotransmitter binds to postsynaptic receptors

____ is a type of membrane transport protein that increases the potential energy across a membrane

A pump

A flow of electrical current is called an ____ _____ is generated within the initial segment of a neuron

Action potential

Choose which of the following can be the mechanism by which neurotoxins may do harm

Alter events that occur at a synapse Interfere with transmission of action potentials Induce detrimental structural change to a neuron

The nerve impulse causes ____ in the number of calcium ions that enter the synaptic knob

An increase

Voltage gated sodium channels _____ during the relative refractory period

Are returning to resting state

______ are star-shaped.

Astrocytes

A ____ is best described as a channel that is usually closed that open in response to binding a neurotransmitter and that when open, allow a specific type of ion to diffuse across the plasma membrane

Chemically gated channel

The main activity of the ____ is propagation of an action potential along the axolemma

Conductive segment

If ohms law is rearranged to voltage = "A" X Resistance, the term "A" should be ______

Current

The movement of charged particles is known as

Current

A positive change in the membrane potential is called______

Depolarization

The electrochemical gradient is formed when a combination of the _____ gradient and the _____ gradient

Electrical: chemical

An individual axon is wrapped in a connective tissue covering called the _____

Endoneurium

Ion channels use the energy of ATP to maintain concentration gradients across neuron membrane

False

___ is what underlies the absolute refractory period

Inactivation of sodium channels

Many local anesthetic prevent transmission of pain by _____

Inhibiting voltage gated sodium channels

____ channels allow inflated flow of specific ions from regions of high concentration to regions of low concentration

Leak

____ cells wander through the CNS and replicate in response to an infection

Microglial

____neurons are most common

Multipolar

An _____ is much more efficient because saltatory conduction occurs and less energy is required to maintain the RMP

Myelinated axon

Is/are considered "nerve glue"

Neuroglial cells

The ability to alter to a response of neurons to neurotransmitters is known as

Neuromodulation

intracellular

Organic ions

A ______ transmits an impulse through its axon toward the synapse

Presynaptic neuron

____ is a type of membrane transport protein that increases the potential energy across a membrane

Pump

_____ is the return of polarity from positive back to negative (the RMP)

Repolarization

A nerve impulse that "jumps" from mode to node is called a ______ conduction

Saltatory

___ help regulate fluid composition including the exchange of nutrients and waste in the nervous system

Satellite cells

Extracellular

Sodium ions

The conductive segment of a neuron is/ are the

Total length of axon

____ neurons have a single, short neuron process that emerges from the cell body and branches like a T

Unipolar

What two are division of the sensory nervous system

Visceral and somatic division

____ are unique channels in that they have three states; resting, activation, and inactivation

Voltage gated channels

A substance synthesized at the cell body must undergo _____ transport to reach the synaptic knobs.

anterograde

The plasma membrane of an axon is called the

axolemma

The myelin sheath covers

axon

A soma is another name for

cell body

Dendrites branch off of the

cell body

the epineurium is made of ______ connective tissue

dense irregular

The tissues that receive nerve impulses from motor neurons are called _____

effectors

The choroid plexus is made from capillaries and

ependymal cells

When chemically or voltage gated channels open, there is a change in ion ______ across a membrane

flow

Neurons are classified ___ depending on the direction the nerve impulse travels

functionally

The electrical gradient in a resting neuron is such that the _____ of the cell is negative relative to the _______

inside and outside

The resting membrane potential is measured in

millivolts

______ are chemicals released from synaptic knobs and bind to receptors on postsynaptic membranes

neurotransmitters

_____ are large cells that ensheath many different axons

oligodendrocytes

A fascicle is surrounded by a layer of dense irregular connective tissue called:

perineurium

Voltage is a measure of relative ___ energy

potential

____ are membrane molecules that use the energy of ATP to move ions against a concentration gradient

pumps

during ______ ______ an axon is either incapable of generating an action potential or requires a larger than normal stimulus

refractory period

The opposition to the movement of electrical charge is known as

resistance

The somatic _____ division of the nervous system receives information from the skin, fascia and joints

sensory

Interneurons facilitate communication between ____ neurons and ____ neurons

sensory and motor

Identify all of the components of the central nervous system

spinal cord and brain

Neurons integrate multiple synaptic inputs by the process of ______

summation

The junction between an axon and another cell is called a ______

synapse

if several EPSPs occur at a synapse over a shot period of time, they undergo ______ at the initial segment

temporal summation

Which of the following are true of neurolemmocytes

they create the myelin sheath in the PNS, they are also called Schwann cells

The all or none law refers to the fact that action potentials will only occur if the initial segment reaches

threshold

In the initial segment, an action potential is generated if the membrane potential reaches the

threshold value

most afferent neurons are classified functionally as __________

unipolar