Types of Neurotransmitters/Hormones + Structure of a Neuron

Excitatory Neurotransmitters

Chemicals that make a neuron more likely to send a nerve signal

Inhibitory Neurotransmitters

Chemicals that make a neuron less likely to send a nerve signal.

Hormones

Chemical messengers made by glands that travel through the blood to control body functions and behaviors.

Endocrine System

• Uses hormones to control growth, metabolism, and mood.

• Hormones travel through the blood to reach different organs.

• The hypothalamus and pituitary gland help control hormone levels

Adrenaline (HORMONE)

Responds to stress or excitement and prepares body for fight-or-flight response, increasing heart rate

Oxytocin (HORMONE)

Known as the ‘love hormone’, involved in social bonding, childbirth, milk release

Melatonin (HORMONE)

Regulates sleep cycle

Leptin (HORMONE)

Produced by fat cells and regulate energy balance; signals brain to reduce appetite after fullness

Ghrelin (HORMONE)

Stimulates hunger, also known as “hunger hormone”

Achetecholine (NEUROTRANSMITTER)

Muscle contraction, learning, memory

Nonrepinephrine (NEUROTRANSMITTER)

Alertness, arousal, focus

Substance p (NEUROTRANSMITTER)

Involved in transmitting pain signals to brain; plays role in pain transmission

Endorphins (NEUROTRANSMITTER)

Acts as natural pain killer, enhances mood, euphoria

Serotonin (NEUROTRANSMITTER)

Regulates mood, appetite, sleep

Dopamine (NEUROTRANSMITTER)

Reward, motivation, attention, learning, movement

Glutamate

MAIN excitatory neurotransmitter; learning and memory (Essential for cognitive functions)

GABA

Main inhibitory neurotransmitter; calms neural activity (Helps calm nervous system and promotes relaxation)

Cell body (Soma)

Consists of the nucleus and vital organelles and serves as the metabolic center of the neuron

Dendrites

Branchlike structures that receive incoming messages from other neurons

Axon

Long fiber that transmits impulses away from the cell body; covered in myelin sheath in order for faster signal transmission (Critical for effective communication)

Myelin Sheath

Fatty layer that covers the axon and speeds up neural transmission

Axon Terminals

Branches at end of axon that release neurotransmitters

Resting Potential

Neuron is resting and ready to send a message

Type of potential

• Excitatory → more likely for neuron to fire

• Inhibitory → less likely for neuron to fire

Threshold

Minimum stimulation needed to fire (Reaching threshold causes depolarization and action potential)

All or nothing principle

Neuron either fires completely or not at all

Refractory period

Brief recovery time before neuron can fire again