Chapter 12: Nervous Tissue

The somatic ___________ division of the nervous system receives info from the skin, fascia and joints

sensory

What are reasons for the very limited regeneration of damaged axons in the CNS?

-Astrocytes create scar tissues inhibiting growth -Axons are crowded in CNS.

What processes are occurring during the synaptic delay?

-Binding of neurotransmitter to receptors -Diffusion of neurotransmitter -Release of neurotransmitter

What are the structural classifications of neurons?

-Bipolar -Unipolar -Multipolar

The CNS is made of the __________ and spinal __________

-Brain -Cord

What pumps can you find in the plasma membrane?

-Ca2+ -Na+/K+

What are considered types of effectors?

-Cardiac muscle -Skeletal muscle -Glands

Synapses are classified as ________________.

-Chemical synapses -Electrical synapses

What segments of a neuron contain large numbers of voltage gated potassium channels and voltage gated sodium channels?

-Conductive segment -Initial segment

What are some general characteristics of graded potentials?

-Degree of change in membrane potential is dependent of the stimulus magnitude -Can either be depolarizing or hyperpolarizing -Decrease intensity with distance traveled along membrane

The "E" in EPSP stands for __________, meaning that the potential makes the inside of the postsynaptic cell more __________________.

-Excitatory -Positive

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

-Inside -Outside

What conditions can make a PSP larger?

-More postsynaptic channels open -More transmitter is released

Assuming a threshold voltage is reached, sodium ions enter through a voltage gated sodium channel. What events would immediately follow?

-More voltage gated sodium channels would open -The membrane potential would reverse (become positive)

What are the functional classes of neurons?

-Motor neurons -Interneurons -Sensory neurons

What ions have leak channels on the plasma membrane?

-Na+ -K+

Synapses occur where axons contact ______________.

-Other neurons -Gland cells -Muscle cells

What are the functions of astrocytes?

-Regulates the composition of interstitial fluid -Replaces damaged neurons -Helps form the blood-brain barrier

What membrane transporters are present throughout the membrane of a neuron?

-Sodium leak channels -Na+/K+ pumps -Potassium leak channels

The components of somatic sensory division are what?

-Taste -Joints and muscles -Hearing

What must happen in order for a chemical signal to change the membrane potential of a neuron?

-There must be a change in ion flow across the membrane -There must be a change in the number of open ion channels

Which of the following are true of neurolemmocytes?

-They create the myelin sheath in the PNS -They are also called Schwann cells

What are the two divisions of the sensory nervous system?

-Visceral division -Somatic division

According to Ohms law, current is directly related to ___________, and inversely directed to _______________.

-Voltage -Resistance

What events help return the membrane potential to the resting state following hyperpolarization?

-Voltage gated potassium channels close -Na/K pumps restore gradients

Generally, nervous tissue is made up of ________ distinct cell types

2

What type of membrane transport protein increases the potential energy across a membrane?

A pump

A flow of electrical current called _______________ _______________ is generated within the initial segment of a neuron

Action potential

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

A fascicle is a bundle of ____________

Axons

A nerve is a bundle of parallel _____________.

Axons

The neurons in the retina of the eye are _____________.

Bipolar

The nervous system is composed of the ___________, spinal cord, nerves, and ganglia.

Brain

The ependymal cells help produce ___________.

CS fluid

Satellite cells are found surrounding ___________.

Cell bodies

The neuron's control center is the ________________.

Cell body

The epineurium is made of __________ connective tissue

Dense irregular

Motor neurons are classified as ____________ neurons.

Efferent

The electrochemical gradient is formed from a combo of the _____________ gradient and the ______________ gradient.

Electrical Chemical

The net diffusion of a given ion is dependent upon its ___________ _____________.

Electrochemical gradient

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

Endoneurium

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

Neuron cell bodies in the PNS are found clustered in _________________.

Ganglia

A _____________ is a temporary change in membrane potential which lasts only as long as the stimulus that causes it and can vary in size

Graded potential

___________ Occurs when the inside of a cell becomes more negative than the resting membrane potential.

Hyperpolarization

What is an acronym which is used to describe a postsynaptic graded potential in which the membrane becomes more negative on the inside?

IPSP

An action potential is also called a nerve __________.

Impulse

The autonomic nervous system is also know as the __________________.

Involuntary nervous system

_________ channels allow ungated flow of specific ions from regions of high concentration to regions of low concentration

Leak

____________ Cells are the least common glial cell of the CNS.

Microglial

Which glial cell acts as a phagocyte?

Microglial cell

What functional division of the nervous system consists of all axons that transmit a nerve impulse from the CNS to a muscle or gland?

Motor nervous system

Oligodendrocytes create the ___________ sheath in the CNS

Myelin

What cell type is considered "nerve glue"?

Neuroglial cells

The regulation of the response of neurons to neurotransmitters is known as ___________________.

Neuromodulation

What component of nervous tissue conducts electrical impulses?

Neurons

____________ are specialized nervous system structures that detect stimuli.

Neurons

__________ are chemicals released from the synaptic knobs and bind to receptors on postsynaptic membranes.

Neurotransmitters

Do neurons far outnumber glial cells?

No

The motor nervous system is reponsible for____________

Output

What structural division of the nervous system projects information to and receives info from the brain and spinal cord?

PNS

Sensory and motor nerves are part of the ________ nervous system

Peripheral

A graded potential caused by the opening of chemically gated channels on a postsynaptic membrane is known as a _____________ ____________.

Postsynaptic potential

What electrical event immediately follows the binding of neurotransmitter molecules to chemically gated ion channels?

Postsynaptic potential

The sequential opening of voltage gated sodium channels is followed by the sequential opening of voltage gated _____________ channels

Potassium

Voltage is a measure of relative __________ energy.

Potential

What type of neuron transmits an impulse through its axon toward the synapse?

Presynaptic neuron

The nervous system collects info through _______________.

Receptors

During the _____________ _______________, an axon is either incapable of generating an action potential, or requires a larger than normal stimulus.

Refractory Period

The relative difference in charge across the plasma membrane of a resting neuron is known as the __________________.

Resting membrane potential

___________ Nerves always relay information to the CNS

Sensory

Flow of the __________ ion is the most common cause of depolarization

Sodium

The process by which postsynaptic potentials are added together at the initial segment is know as _______________.

Summation

If several EPSPs occur at a synapse over a short period of time, they undergo ________ at the initial segment

Temporal summation

The myelin sheath covers _______.

The axon

If you were moving across a neuron's membrane from the receptive segment toward the transmissive segment, where would you first encounter large numbers of voltage gatd Na+ and K+ channels?

The initial segment

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

Dendrites transfer information __________ the cell body.

Toward

Most afferent neurons are classified functionally as ____________.

Unipolar

Most sensory neurons are __________________.

Unipolar

Which division of the nervous system detects nerve impulses from blood vessels and internal organs?

Visceral sensory division

What is the unique channel that has three states: Resting, activation, and inactivation

Voltage gated channels

The movement of charged particles can be harnessed to do __________________.

Work

The voltage gated sodium channels undergo changes in activity during the depolarization phase of an action potential. Name the sequence of events from first to last.

1) A graded potential depolarizes the initial segment 2) Voltage gated sodium channels open 3) Sodium flows into the neuron at the initial segment 4) Further depolarization of the initial segment occurs 5) Sodium channels enter the inactive state

What are 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 the synaptic cleft 6) Neurotransmitter binds to postsynaptic receptors

What are the events of an EPSP in order?

1) Excitatory neurotransmitter binds to receptor Na+ channel 2) Na+ enters the postsynaptic cell 3) The inside of the cell becomes more positive 4) The local current of Na+ becomes weaker as it moves towards the axon hillock

Name the events of a chloride-based IPSP in order from earliest to latest.

1) Inhibitory neurotransmitter binds to postsynaptic chemically gated chloride channels 2) Chloride moves from outside the cell to the inside 3) The inside of the postsynaptic cell becomes more negative 4) The local chloride current becomes weaker as it moves towards the axon hillock