Chapter 12 Intro to NS

sensory neuron

(afferent neurons) are the neurons of the sensory nervous system. They are responsible for conducting sensory input from both somatic sensory and visceral sensory receptors to the CNS

interneurons

(association neurons) lie entirely within the CNS. They receive stimulation from many other neurons and carry out the integrative function of the nervous system—that is, they receive, process, and store information and "decide" how the body responds to stimuli. Interneurons facilitate communication between sensory and motor neurons.

motor neuron

(efferent neurons) are the neurons of the motor nervous system, conducting motor output from the CNS to both somatic effectors and visceral effectors. All motor neurons are multipolar.

depolarization

-decrease in the membrane potential -inside of cell becomes more positive -a decrease in the extracellular concentration of potassium -an increase in the number of sodium leak channels -opening of voltage gated sodium channels

hyperpolarization

-increase in membrane potential -inside of cell becomes more negative -an increase in the extracellular concentration of potassium -opening of gated chloride channels

local potentials

-ligand gated sodium channels -EPSPs -IPSPs -cause summation -decremental -reversible

action potentials

-voltage gated sodium channels -voltage gated potassium channels -require a threshold -important for transmission over long distances

order for neurotransmitter release

1-Action potential reaches axon terminal 2-Voltage-gated Ca2+ channels open 3-Extracellular Ca2+ enters terminal and binds to sensor protein in the cytoplasm 4-Ca2+-protein complex stimulates fusion of the docked synaptic vesicle with the plasma membrane 5-Exocytosis of neurotransmitter into synaptic cleft

absolute refractory period.

A recently depolarized area of a cell membrane cannot generate an action potential because of the

refractory period

A time when there is a decrease in the sensitivity of the plasma membrane to further stimulation

synaptic cleft

A typical synapse in the CNS consists of a presynaptic neuron and a postsynaptic neuron, separated by a narrow space called the _____ ______.

inhibitory postsynaptic potential.

If neurotransmitter from Neuron A causes Neuron B to hyperpolarize, this is an example of an

multipolar neuron

Multiple processes extend directly from the cell body; typically many dendrites and one axon; most common type of neuron

efferent

Neurons that carry signals from the CNS to skeletal muscle for contraction would be classified as _____________ neurons.

excitatory postsynaptic potentials (EPSPs).

On a graph of an action potential, the small depolarizations that lead to threshold are from

anaxonic neuron

Processes are only dendrites; no axon present

4,1,3,2

Rank in order the events that occur when an action potential reaches the transmissive segment of an axon. 1-Voltage-gated calcium channels open 2-Neurotransmitter diffuses across synaptic cleft 3-Vesicles containing neurotransmitter merge with plasma membrane 4-Action potential reaches synaptic knob

2

Select all that are true of inhibitory postsynaptic potentials. 1-Voltage gated ion channels open and let potassium out 2-The postsynaptic cell hyperpolarizes 3-Chemically gated cation channels open and let chloride in 4-The inside of the cell becomes more positive

2,3,4

Select all the characteristics of graded potentials. 1-They are created along the axon 2-They are the result of chemically-gated ion channels opening 3-The current generated is localized 4-The current generated decreases with distance

unipolar neuron

Single short process extends directly from the cell and looks like a T as a result of the fusion of two processes into one long axon

outside,inside

Sodium has a higher concentration ______ the cell than ________

sensory, motor

The ___________ nervous system transmits information from receptors to the CNS, while the ___________ nervous system transmits information from the CNS to the rest of the body.

synaptic knob

The extreme tips of these fine extensions are slightly expanded regions called

negatively, inside, outside

The negative value of the resting membrane potential means there are more _________ charged particles on the ________ of the membrane than on the _______.

relative refractory period

The time when a stronger-than-threshold stimulus is needed to initiate another action potential.

absolute refractory period

The time when there is complete insensitivity of the plasma membrane to another stimulus.

bipolar neuron

Two processes extend directly from the cell body; one dendrite and one axon; relatively uncommon

A new action potential is produced

What is produced when depolarization of a cell membrane reaches threshold?

chemically-gated sodium channel

When a neurotransmitter binds a protein channel, it opens and lets sodium diffuse down its concentration gradient. This is an example of a

all-or-none law

When threshold is reached, depolarization occurs with the same amplitude of potential change. This is known as the ___________ ______

axon hillock

a triangular region of the cell body

voltage

action potentials arriving at the presynaptic terminal cause ______-gated calcium channels to open

sensory

after processing _____ input, the brain and spinal cord determine what response, if any, is required.

telodendrion

an array of fine terminal extensions called

Receptors

are specialized nervous system structures that monitor changes in both the internal and external environment called stimuli

neurotransmitters

calcium ions diffuse into the cell and cause synaptic vesicles to release ______

ganglia

clusters of neuron cell bodies located along nerves

somatic motor

component initiates and transmits motor output from the CNS to skeletal muscles. For example, you exert voluntary control over your leg muscles as you press on the accelerator of your car.

autonomic motor

component innervates and regulates cardiac muscle, smooth muscle, and glands without our conscious control.

somatic sensory

components detect stimuli that we can consciously perceive. Receptors of the somatic sensory nervous system include the receptors associated with the five senses (i.e., eyes, nose, tongue, ears, skin) and proprioceptors (receptors in joints and muscles that detect body position).

visceral sensory

components detect stimuli that we typically do not consciously perceive. Receptors of the visceral sensory nervous system include structures located within blood vessels and internal organs

Central Nervous System

composed of the brain and spinal cord

Peripheral Nervous System

includes nerves, which are bundles of neuron processes (axons) and ganglia

cell body

is also called the soma, and it is enclosed by a plasma membrane and contains cytoplasm surrounding a nucleus. Cell bodies serve as the neuron's control center

integrating, neurons

it provides a rapid means of _______ and regulating body functions through electrical activity transmitted along specialized nervous system cells called _______

lignad

neurotransmitters combine with their receptor sites and cause ______-gated ion channels to open

presynaptic

neurotransmitters diffuse from the ______ terminal across the synaptic cleft

sensory nervous system

or afferent (af′er-ent; afferens = to bring to) nervous system is responsible for receiving sensory information from receptors that detect stimuli and transmitting this information to the CNS.

motor nervous system

or efferent (ef′er-ent; efferens = to bring out) nervous system is responsible for initiating and transmitting motor output from the CNS to effectors. This system controls muscle tissue and glands.

receptors, stimuli

specialized nervous system structures called _____ monitor changes in both the internal and external environment called ______ to collect information

dendrite

tend to be relatively short, small, tapering, unmyelinated processes that branch off the cell body.

motor, effectors

the brain and spinal cord initiate a response as _____ output via nerves to _______. these structures include all three types of muscle tissue and glands

ions

the diffusion of ______ into the cell or out of the cell causes a change in membrane potential

nervous system

the following are functions of the _____ _______ Processing and evaluating information Collecting information Responding to information

communication

the nervous system serves as the body's primary _________ and control system

true

true or false Postsynaptic neurons can generate both inhibitory and excitatory postsynaptic potentials simultaneously.