Unit 3 Challenge 1

Postsynaptic Cell

The cell at a synapse to which the neurotransmitter binds

Interneurons

Interneurons are neurons found in the central nervous system, which includes the brain and the spinal cord. They receive information that was collected from sensory neurons and process that information.

Output Zone

The part of the neuron that consists of the axon endings where signals are sent on to another neuron or to a gland or muscle cell

Input Zone

The region of a neuron where signals enter (usually the dendrites around the cell body)

Neuron

A nerve cell responsible for relaying information within the nervous system

Myelin Sheath

An insulating layer that surrounds axons neurons in the nervous system and allows action potentials to propagate more quickly

Which type of neurons are found primarily in the spinal cord and brain?

Interneuron

Motor Neurons

Motor neurons are the third type of neuron in the nervous system and their function is to relay information to muscles or glands. Then these muscles and glands are going to carry out some sort of response depending on the information that they receive.

Inhibiting Signals

Neurotransmitters that inhibit or prevent action potentials

Resting Membrane Potential

The difference in the charge across a cell membrane which has the potential for an action potential to occur

Schwann Cells

The glial cells that compose the myelin sheath in the peripheral nervous system

Threshold

The minimum voltage shift across a membrane required for an action

Trigger Zone

The part of the neuron located at the base of the cell body that initiates action potentials

Resting Potential

The steady voltage difference that occurs across a neuron's membrane when it is not being stimulated

Botox

A bacterial toxin that is often used to smooth facial wrinkles by stopping the release of the neurotransmitter acetylcholine; technically, it's not an inhibiting signal; it stops the signal from being sent, rather than sending a signal that tells a neuron not to have an action potential

Nervous System

A body system that collects, interprets, and responds to stimuli from the environment

What is a neurotransmitter?

A chemical signal between cells

Action Potential

A nerve impulse

Action Potential: term

A nerve impulse

Nerve

A nerve is a bundle of axons of neurons

Axon

A part of a neuron that conducts signals away from the cell body and on to another cell

Dendrite

A part of a neuron that receives incoming information

Sodium/Potassium Pump

A protein embedded in the plasma membrane that actively transports sodium and potassium against their concentration gradients

During a medical examination, the doctor taps your knee with a little rubber mallet. Suddenly, your foot kicks upward.How did this reflex occur?

A sensory neuron sent a signal to the spinal cord and synapses with a motor neuron, triggering a muscle contraction.

Which part of the neuron transmits signals to other neurons, glands or muscle cells?

Axon endings

Which is the correct sequence of the flow of nerve impulses in a neuron?

Dendrite → Axon → Axon terminal

Central Nervous System (CNS)

Division of the nervous system that consists of the brain and spinal cord; is the processing center of the body, and contains interneurons

Peripheral Nervous System (PNS)

Division of the nervous system that sends signals to and from the central nervous system and contains sensory and motor neurons

Which type of neuron directs gland and muscle cells to carry out a response?

Motor neuron

Which of these is an insulating material that allows nerves to transmit action potential faster?

Myelin sheath

How do neurons communicate?

Neurons communicate with other neurons, muscle fibers and glands, and they communicate with all these different tissues in pretty much the same way. Let's take a motor neuron communicating with a muscle fiber as an example. Neurons are long and communication among them has to be fast; think about how quickly you go from the decision to raise your hand to the action itself. What's the fastest way to send a signal along the long nerve cell? Electricity. (This is about how fast a light bulb glows after you flip the switch.)

What does a neurotransmitter bind to?

Postsynaptic cell

What is the name of a synapse that stores a neurotransmitter for release?

Presynaptic cell

Reflexes

Reflexes are the simplest nerve pathway and are an automatic movement as a result of a stimulus, so it doesn't take conscious effort for a reflex to occur. Reflexes can involve interneurons, or sometimes a motor neuron will synapse directly with a sensory neuron. A very simple reflex just involves sensory neurons and motor neuron synapsing with each other. However, most interactions involve an interneuron.

Exciting Signals

Signals that trigger an action potential to happen

Ions of which two elements produce an electrical charge across the membrane of a neuron to cause a nerve impulse?

Sodium and Potassium

Action Potential

Step 1: Stimulation First, stimulation has to occur. Signals will reach the input zone of a neuron and will change what occurs in the cell membrane of that neuron. Step 2: Open Sodium Gates This stimulus will cause sodium gates in the membrane of the cell to open, which allows sodium to rush into the cell. Normally in a resting membrane, the outside of the cell is positive relative to the inside of the cell. As these sodium gates open, sodium will rush in, causing more gates to open until that threshold we discussed is reached, causing the voltage difference across the cell membrane to reverse.Step 3: Restore Resting Membrane Potential Now in order for another action potential to occur, you have to restore the resting membrane potential which is done so by sodium-potassium pumps. To understand this, it is important to review the structure of a neuron here. A neuron is a nerve cell and made up of dendrites, which are part of the input zone. Information will move through the input zone, through the dendrites, to the cell body. From there, the action potential will travel along this long narrow part of the neuron called the axon, and then down to the axon endings. So information goes through the input zone, through the cell body, along the axon, to the axon endings. Then from there, that signal will be sent either to another neuron or to a muscle or a gland cell.

Presynaptic Cell

The cell at a synapse that stores a neurotransmitter for release

Neurotransmitter

The chemical form of a signal that is sent between neurons and muscle cells, gland cells or other neurons

Select the TRUE statement about a resting neuron. a.)The cytoplasm side of a neuron is negatively charged while the outside of the neuron is also negatively charged. b.)The cytoplasm side of a neuron is positively charged while the outside of the neuron has no charge. c.)The cytoplasm side of a neuron is more positive than the outside of the neuron. d.)The cytoplasm side of a neuron is more negative than the outside of the neuron.

The cytoplasm side of a neuron is more negative than the outside of the neuron.

Synapse

The gap between a neuron and a gland cell, muscle cell, and another neuron

Sensory Neurons

The purpose of sensory neurons is to collect information about stimuli. Sensory neurons can be found throughout the body and can sense information like temperature and light (stimuli from the external environment) and the chemicals in your body's extracellular fluid (stimulus from the internal environment), to name just a few of the many examples. You have various types of sensory neurons that allow you to collect information about different types of stimuli.

A __________ is an automatic movement in response to a stimulus, such as jerking your lower leg when your knee is struck with a mallet.

reflex