Chapter 12 Activities - Nervous System

Long fiber that carries nerve impulses to target

Axon

Bundle of axons

nerve (PNS)

Connection between adjacent neurons

synapse

Chemical secreted into gap at a synapse

neruotransmitter

Rapid automatic response to a stimulus

Reflex

Fatty covering that speeds up nerve impulses

myelin sheath

Structure at end of axon that produces neurotransmitters

axon terminal

High speed signals that pass along the axons of nerves 

nerve impulses 

Branching filaments conduction nerve impulses toward cell

dendrites

Sense organ or cells receiving stimuli from within and outside the body

Sense receptors

Reaction to a stimulus by muscle or gland

response

Part of nerve cell containing the nucleus

Cell body (soma)

Nerve cell that carries impulses from sense receptor to brain or spinal cord

sensory neuron

Nerve cell that connects sensory and motor neurons

relay neuron (interneuron)

Nerve cell that transmits impulses from the brain or spinal cord to muscle or gland 

motor neuron 

4 major functions of the nerous system

1. Sensation

2. Response

3. Integration

4. Higher level functions

neurons that carry messages from sensory receptors and send them to the central nervous system

Sensory Neuron

Neurons that carry messages away from the central nervous system and out to the rest of the body

Motor Neuron

When a neuron is stimulated enough, it fires a(n) _______ impulse down it’s axon to its neighboring neurons

Electrical

What transmits messages between the central and peripheral nervous systems.

Interneuron

A resting neuron has more negative charge on the _____ of it than in the extracellular space around it.

Inside

Neurons have a resting membrane potentially became outside there are a bunch of positively charged _____ ions.

Sodium

Inside there are positively charge ______ ions, but also bigger, negatively charge proteins

Potassium

Since there are more positive charges inside the outside, the neuron is negatively charged, or ______

Polarized

When an axon is in the middle of an action potential, it can’t respond to any other stimulus, no matter how strong. This is called the ______. The strength of the action potential remains the same. What does change is the ______

1. Refractory period

2. Frequency

Electrical Synapses send an ion current directly from one neuron to another though ______. The signal is never converted into another form. Chemical Synapses are slower and more abundant. They use neurotransmitters that diffuse across synaptic gaps. They can ____ the signal, allowing ways to control it.

1. synaptic cleft

2. Convert

_______ meeting point between two neuron

Gap junctions

Your nerve cells have two main settings for communication _______ and _______

1. Electrical

2. Chemical

What order do this events go in?

1. Potential difference across membrane reaches +40mV and voltage-gated sodium ion channels close.

2. Energy of a stimulus triggers some voltage-gated sodium ion channels to open, and sodium ions diffuse into axon cytoplasm

3. More potassium ions diffuse out of axon until membrane is hyperpolarized. The potassium channels close.

4. Axon membrane has a resting potential of -65 to -70m; voltage-gated sodium ion channels are closed

5. Voltage-gated potassium ion channels open, and potassium ions diffuse out of the axon

6. More voltage-gated sodium ion channels open, and more sodium ions diffuse into the axon

4, 2, 6, 1, 5, 3

A stable voltage across a neuron’s membrane is called its

Resting membrane potential

The range of a neuron’s resting membrane is _____ to _____

1. -30mV

2. -90mV

Causing the resting membrane potential is the uneven distribution of ____ between the inside and outside of the cell, primary _____ and _____

1. Ions

2. Na+

3. K+

When a membrane’s potential becomes more positive, it is said to become ______

Depolarized

If the membrane potential becomes more negative, it becomes ______

Hyperpolarized

There is another ion that is part of the cell, and is negatively charged, which is _____

CI

The resting potential of the neuron membrane is mostly due to the movement of _______ though leak channels

NA+, K+

Depolarization

Resting

Hyperpolarization