Nervous System, Neurons, and Neurotransmitters

Question 1

What Comprises the Nervous System

Answer 1

Central Nervous System (CNS)
Peripheral Nervous System (PNS)
Somatic Nervous System (SNS)
Autonomic Nervous System (ANS)

Question 2

Central Nervous System (CNS)

Answer 2

Integrates and processes information received from the senses.
Controls voluntary and involuntary actions.
Regulates bodily functions and behaviors.
Includes the brain and spinal cord.

Question 3

Peripheral Nervous System (PNS)

Answer 3

Transmits sensory information from the body to the CNS.
Carries motor commands from the CNS to muscles and glands.
Coordinates involuntary actions, such as digestion and heartbeat.
Includes nerves outside the brain and spinal cord.

Question 4

Somatic Nervous System (SNS)

Answer 4

Controls voluntary muscle movements.
Receives sensory input from the skin, muscles, and joints.
Sends information to the CNS for processing.
Enables conscious perception and response to stimuli.

Question 5

Autonomic Nervous System (ANS)

Answer 5

Regulates involuntary bodily functions, such as heartbeat and digestion.
Maintains homeostasis by adjusting internal processes.
Divided into sympathetic and parasympathetic branches.
Sympathetic branch prepares body for action, while parasympathetic branch promotes rest and relaxation.

Question 6

Sympathetic Nervous System
Autonomic Nervous System (ANS)

Answer 6

Activates the body’s fight-or-flight response during emergencies or stress.
Increases heart rate and blood pressure.
Dilates pupils to improve vision.
Inhibits digestion to conserve energy.
Stimulates sweating to cool the body.
Releases adrenaline and noradrenaline to prepare for action.

Question 7

Parasympathetic Nervous System
Autonomic Nervous System (ANS)

Answer 7

Promotes rest and relaxation after a stressful situation.
Slows heart rate and decreases blood pressure.
Constricts pupils to reduce light intake.
Stimulates digestion and nutrient absorption.
Contracts bladder muscles for urination.
Supports normal bodily functions during non-stressful situations.

Question 8

Neurons

Answer 8

The nervous system contains two types of cells – neurons and glia. Neurons are responsible for communicating information within the nervous system, while glia serve several functions including providing neurons with structural support, insulation, and nutrients.

Question 9

Structure of the Neuron

Answer 9

Neurons vary in size and shape, but all have one or more dendrites, a soma (cell body), and an axon. The dendrites receive information from other cells; the soma contains the nucleus, mitochondria, ribosomes, and other elements essential for the survival of the cell; and the axon transmits information to other cells. Some axons are insulated with myelin, which is produced by glia and speeds up the conduction of information through the axon.

Question 10

Conduction Within Neurons

Answer 10

Begins when dendrites receive sufficient stimulation.
Neuron is in a resting state before stimulation.
Stimulation causes depolarization as positively charged sodium ions enter the cell.
Depolarization reaches a threshold, triggering an action potential.
Action potential is an all-or-none response.
Stimulus intensity is encoded by the frequency of action potentials.

Question 11

Transmission Between Neurons

Answer 11

Occurs at synapses.
Action potential reaches axon terminal.
Neurotransmitter released into synaptic cleft.
Neurotransmitter can be excitatory or inhibitory.
Neurotransmitter affects postsynaptic neuron’s likelihood of firing.
Neurotransmitter is inactivated after effect on postsynaptic neuron.

Question 12

Neurotransmitters

Answer 12

Neurotransmitters are chemical substances that transmit information between neurons.

Question 13

The major neurotransmitters include the following:

Answer 13

Dopamine
Acetylcholine (ACh)
Glutamate
Norepinephrine
Serotonin (5-HT)
Gamma-Aminobutyric Acid (GABA)
Endorphins

Question 14

Dopamine

Answer 14

Function: Serves both excitatory and inhibitory functions. Contributes to movement, personality, mood, and sleep.
Disorders: Parkinson’s disease (low levels in the substantia nigra), Tourette’s disorder (excessive levels in the caudate nucleus), schizophrenia (high levels or hyperactivity).

Question 15

Acetylcholine (ACh)

Answer 15

Function: Excitatory and inhibitory. Involved in movement, arousal, attention, and memory.
Disorder: Myasthenia gravis (muscle weakness by destroying ACh receptors).

Question 16

Glutamate

Answer 16

Function: Excitatory. Contributes to movement, emotions, learning, and memory.
Disorders: Glutamate-induced excitotoxicity (cell damage and death) linked to stroke, seizure disorders, Huntington’s disease, Alzheimer’s disease.

Question 17

Norepinephrine

Answer 17

Function: Excitatory. Involved in arousal, attention, learning, memory, stress, and mood.
Disorders: Some forms of depression (deficiency), mania (excessive levels).

Question 18

Serotonin (5-HT)

Answer 18

Function: Inhibitory. Plays a role in arousal, sleep, sexual activity, mood, appetite, and pain.
Disorders: Depression, suicide risk, bulimia nervosa, obsessive-compulsive disorder, migraine headaches.

Question 19

Gamma-Aminobutyric Acid (GABA)

Answer 19

Function: Inhibitory. Involved in memory, mood, arousal, sleep, and motor control.
Disorders: Insomnia, seizures, anxiety.

Question 20

Endorphins

Answer 20

Function: Inhibitory. Similar effects to opioid drugs, contributing to pleasure, well-being, and analgesia.
Use: Acupuncture may stimulate their release to relieve pain.

Question 21

Neurotransmitters and Drug Effects

Answer 21

Psychoactive drugs vary from weak to strong in terms of their binding affinity (tendency to bind to receptor sites on postsynaptic cells) and receptor efficacy (tendency to activate receptors). They can also be classified on the basis of their effects on neurotransmitters.

Question 22

Agonists

Answer 22

Mimic or increase the effects of a neurotransmitter.

Question 23

Partial agonists

Answer 23

Produce effects that are similar to (but weaker than) the effects of a neurotransmitter

Question 24

Inverse agonists

Answer 24

Produce effects that are the opposite of the effects of a neurotransmitter or agonist.