L6- Test 2 Flashcards by Hailey Lopez

What is the function of the nervous system?

To control/ coordinate body functions

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What is the nervous systems goal?

To maintain homeostasis

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The functional unit of the nervous system are ________

Neurons

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What are the 2 types of signals?

Chemical and electrical

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Electrical signaling

Happens in a neuron

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Chemical signals

Happen between 2 neurons

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Central (CNS) nervous system

Brain and spinal cord

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Peripheral (PNS) nervous system

Nerves and ganglia

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Tracts (CNS)

Bundle of neuron axons

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Nuclei (CNS)

Cluster of neuron cell bodies

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Nerve (PNS)

Bundle of neuron axons

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Ganglia (PNS)

Cluster of neuron cell bodies

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What are axon collaterals?

Branching of axon - allowing communication w/ many neurons

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What are the 3 structural classifications of neurons?

unipolar, multipolar, bipolar

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Structural classifications of neurons are based on ________ of cell bodies

Polarity

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What are the 3 functional classifications of neurons?

Sensory, interneuron, motor neuron

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Interneurons are found where and tend to be what structural cell?

Completely in cell ; multipolar

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Motor neuron somatic found where

In skeletal muscle; multipolar

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Motor neuron are found where

Cardiac muscle, smooth muscle, and glands ; multipolar

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What do sensory neurons do?

They sense the environment

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What do interneurons do?

They integrate sensory input and initiates motor output

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What do motor neurons do?

They carry out the signal from the interneuron

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Synapses

Junction/ communication b/w 2 cells

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What are the two types of neural pathways and how are they different?

Simple - processing by 1 interneuron

Complex - processing by a chain of interneurons

Afferent

Arrive (sensory)

Efferent

Exit/ motor

Reflex arc includes….

1. Receptor 2. Sensory neuron 3. Interneuron 4. Motor neuron 5. Effector

The 2 cell types of the nervous system include _________ and ___________

Neurons - conduct electrical signals & neuroglial cells - doesn’t conduct electrical signals

Astrocytes form…..

The blood brain barrier in CNS

Schwann cells form….

Myelin in PNS

Oligodendrocytes form….

Myelin in CNS

Communication of a neuron

1. Cell body/ dendrites - integrate physical/ chemical input 2. Axon - conduct electrical signals 3. Axon terminals - release neurotransmitters

How do neurons create electrical signals of communication?

Changes in membrane potential

How do neurons communicate with each other ➡️ create neural pathways

Neurotransmitters bind to receptors in synapse

Membrane potential

The voltage difference across a membrane

What cause the -70mv resting membrane potential?

- the Na+/K+ pump ; 3 Na+ out and 2 k+ in - more k+ leak channels than Na+ channels - having large negatively charged proteins stuck inside cell

Depolarization

Membrane becomes less polar - na+ voltage gated channel opens

Repolarization

Membrane returns to the resting membrane potential

Hyperpolarization

Membrane becomes more polar - k+ continue moving out while ca+ channel closed REFRACTORY PERIOD

Threshold potential

Change in membrane potential required to generate an action potential

Action potential (Ap)

Temporary and transient all or none change in RMP

Graded potential (Gp)

Small change in membrane potential (hyperpolarizing/ depolarizing)

Generation of action potentials occur at

Cell bodies - needs to get at threshold potential in order to release action potential

Initial segment is found at _________

The beginning of axon

Excitatory postsynaptic potential (Epsp)

Moves resting membrane potential closer to threshold potential

Inhibitory post synaptic potential (Ipsp)

Moves resting membrane potential further from threshold potential

What causes change in resting membrane potential?

Regulated opening/closing of specific gated ion channels ➡️ voltage gated ion channels

What ions are responsible for action potentials during depolarization? Repolarization? Hyperpolarization?

Depolarization — voltage gated Na+ channels open ( initiated by graded potentials) Repolarization — voltage gated k+ channels open (initiated by depolarization) Hyperpolarization — k+ continues to move out (producing refractory period)

Significance of refractory period (RP)

1. Ensures each action potential is an individual event 2. Prevents action potentials from moving backwards in an axon

What are the two types of refractory periods?

Absolute refractory period — voltage gated Na+ channels = inactive/ can’t open Relative resting potential— voltage gated Na+ channels = closed but can open w/ strong stimulus

Myelinated vs unmyelinated axons (AP propagation)

Unmyelinated — cycle based ➡️ depolarization, Repolarization, resting membrane myelinated — faster ; contain node of ranvier w/ voltage gated na+ channels

Action potential

Propagation speed down neurons axon

What factors increase an action potentials propagation speed?

Myelin ( saltatory conduction) & larger axon diameter

Slow neurons vs fast neurons

Slow - thin unmyelinated fibers Fast - think myelinated fibers

How is a week signal distinguished from an intense signal?

The intensity of stimulus depends on the frequency

By increasing stimulus frequency it ________ action potential frequency

Increases

Decreasing stimulus frequency it _________ action potential frequency

Decreases

What is the difference between a single action potential and a propagation of action potentials?

Action potential = all or none event that happens once and takes place on small part of axons membrane (not traveling down) Propagation = one action potential initiates (through influx of na+) a depolarization in adjacent downstream axon membrane creating an Ap ➡️….. NERVE SIGNAL

What is the nerve signal that reaches your brain?

Action potentials