1. Nervous System

Vocabulary flashcards covering key terms from a lecture on nervous system structure, cells, and neurophysiology.

Nervous System

The body’s fast communication system that uses electrical signals for sensation, movement, thoughts, and emotions.

Central Nervous System (CNS)

The brain and spinal cord, where information is processed.

️Peripheral Nervous System (PNS)

All nerves outside the CNS, cranial and spinal nerves. connects the CNS to the body.

Sensory (Afferent) Division

Nerves carry signals into the CNS

Receiving information about the environment - stimulus

5 big senses : taste smell touch sight feelings

Integration

Connects sensory and motor neurons, In CNS only - information processed here

Motor (Efferent) Division

Nerves carry commands to effector; which are muscles or glands “E for exit”

Data sent to your CNS that you are unaware of

Visceral branch of the afferent PNS

INCLUDES : heart rate, blood pressure, kidney functioning, etc.

Somatic Nervous System

• everything you think about doing

Goes with Afferent & Efferent PNS

Afferent : nerves carry sensory info from the skin, skeletal muscles, joints and special senses

Efferent : nerves carry motor commands to skeletal muscles

Two types of somatic branch

You decide to move your skeletal muscles

Your body decides to move your skeletal muscle for you

Automatic Nervous System

Goes with Efferent

Automatically controlling internal organs

Nerves carry motor commands to smooth/cardiac muscles and glands

Sympathetic Activation/Division

Division is the flight or flight response

Parasympathetic Activation/Division

Rest and digest mode, makes sure our mouth has saliva we poop and pee, things like that.

Voluntary

Response governed by the somatic nervous system ( contraction of skeletal muscles )

Involuntary

Governed by the automatic nervous system ( contraction of smooth muscles, regulation of cardiac muscle, activation of glands)

Neurons

(Nerve cell) Cells that transmits electrical impulses

Cell Body

Soma, Contains nuclear and organelles

Dendrites & Axon

Branching extensions, carries impulses to the cell body

Single process, carries impulses away from the cell body

Functional classifications of neurons

2 Steps

Sensory neuron and motor neuron

First Step : Sensory Neuron

Pick up data/sensation from your body

Ex . Pain from a needle

1 : Motor Neuron

Response

Neuron that sends signals from the CNS to muscles or glands to take action

1 : Interneurons

Interpretation/integration

• stimuli are compared with other information before a decision is made about the response

2 : The number of the axons

Two cell types of the nervous system:

Neurons, Neuroglia

Neurons

Nerve Cell, does the function (generates and transmits electrical impulses)

Neurons have one axon

Basis of the nervous tissue

Neuroglia (Glial Cells)

Supportive cell, sticks neurons together, supports them, protects them

CNS 4 :

Astrocytes, microglia, ependymal cells, oligodendrocytes

PNS 2 :

Satellite cell, Schwann cells

CNS NEUROGLIA BELOW

Astrocyte

Star-shaped CNS cell that supports neurons (in brain/spinal cord) and forms part of the blood–brain barrier. Prevents waste/harm to neurons.

Microglia

Small CNS cell that removes debris/dead harmful microorganisms in the CNS, destroy and eat

Ependymal Cell

CNS cell lining ventricles; that secretes and circulates fluid

Oligodendrocyte

CNS cell with few processes, forms myelin sheaths around multiple axons.

PNS NEUROGLIA BELOW

Schwann Cell

PNS cell that creates the myelin sheath around a single axon (same as CNS-oligodendrocytes)

Satellite Cell

PNS cell that surrounds and protects neurons in the PNS

Myelin & Myelin Sheath

Supposed the axon of neurons creates a myelin sheath

Myelin sheath - formed by oligodendrocytes and Schwann cell by wrapping around the axon, covering around axons that greatly speeds impulse conduction.

Node of Ranvier

Gap in the myelin sheath, where action potentials are regenerated

Action Potential

Reversal of membrane charge that travels along an axon as a nerve impulse.

Resting Membrane Potential

Electrical charge difference across a neuron’s membrane at rest (\approx -70 mV).

Inside cell = negative

Outside cell = positive

Sodium out / potassium&protein inside

Protein = - charge

Chemical gradient

Making the inside more negative then the outside, the difference in distribution of ions

Electrical gradient

Difference in electricity

(inside -/outside +)

Depolarization

the inside becomes less negative - sodium channels open up making that happen ( sodium gushes into cell )

Threshold Potential

(\approx -55 mV) no return point, all sodium channels open up suddenly and shoot in = actin potential

Repolarization

Return of the membrane potential (negative again) toward resting values due to potassium

Hyperpolarization

Membrane potential becoming more negative than the resting level after repolarization.

Neurophysiology :

your nervous system interacting with the stimulus of the water temperature and determining the appropriate response.

(Neurophysiology) : Voltage

Ion channel that opens or closes in response to changes in membrane potential.

The cell membrane is selectively permeable

Meaning it regulated what’s allowed to cross the membrane and what stays on only one side

Ex. Ions (charged particles), cannot pass through the cell membrane without assistance; they require protein channels or protein pumps to cross the membrane

Sodium–Potassium Pump

Constantly at work, ATP-driven transporter that restores ion balance by moving 3 Na⁺ out and 2 K⁺ into the cell.

Synapse

Function between two neurons or a neuron and an effector where information is transmitted.

Electrical synapse

connection between two cells is so tight that an action potential traveling down an axon will just step over the tiny gap between the cells and continue on in the next cell, causing it to depolarize.

STRUCTURE OF CHEMICAL SYNAPSES ex. of one -

Neuromuscular Junction - where a motor neuron from the brain meets up with a muscle fiber

Presynaptic Neuron

Neuron that sends the signal at a synapse.

Postsynaptic Neuron

Neuron that receives the signal at a synapse.

Synaptic Cleft

Fluid-filled gap between pre- and postsynaptic membranes.

Neurotransmitter

Chemical messenger released at synapses to transmit signals across the synaptic cleft. Initiate depolarization

Excitatory Potentials

binding of neurotransmitter causes depolarization

Inhibitory Potentials

Binding of neurotransmitter causes hyperpolarization

Axon

Long, slender part of a nerve cell that carries impulses away from the cell body and towards other neurons, muscles or glands.

A bundle of axons in the CNS is called

A optic tract

A bundle of axons in the PNS is called

Nerve

Grey Matter CNS & PNS

CNS : Region with many cell bodies

PNS : ganglion same meaning as ^

Dendrite

Short, branching process that receives signals/information from other neurons

Continuous conduction

action potential is slowly moving down the UnMyelinated axon

Saltatory Conduction

Leaping across the myelin axons, allow action potential to move fast across