1.3- The Neuron and Neural Firing

Neurons

basic functional unit of nervous system. They communicate through electrical impulses and chemical signals to send information throughout the body

Soma

the cell body of the neuron. contains the nucleus

Nucleus

part that contains genetic material and allows for the neuron to function

Dendrites

receive chemical information from adjacent neurons through receptor sites.

Axon fiber

Longest part of a neuron. carries a signal away from soma and out to the neuron’s terminal branches

Glial cell

AKA schwann cell, wraps around axon and produces myelin sheath. provide support for neurons. insulate neurons to speed up signal transmission, transport nutrients, communicate between neurons

Myelin sheath

covers the axon and protects it from damage. Also increases speed of action potential

Nodes of Ranvier

gaps in the myelin sheath that promote continuing action potential

Axon terminal

endpoint of a neuron. Neurotransmitters are released into the synaptic gap

Interneurons

neurons within the brain and spinal cord that communicate internally and connect sensory neurons to motor neurons

Reflex arc

a nerve pathway that allows the body to respond to a stimulus without thinking

All or nothing principle

A neuron will only fire if the threshold is met

Threshold

minimum amount of stimulation required for neuron to fire and release action potential

Refractory period

brief period where neuron cannot fire again. Neuron recharges and returns to its resting state.

Synapse

the space between the axon terminal of one neuron and the dendrite of another neuron

chemical synapses

use neurotransmitters to send messages through nervous system

electrical synapses

messages that need to be sent quickly and immediately

presynaptic terminal

axon terminal of the neuron that converts electrical signal into a chemical one and sends neurotransmitters into the synaptic gap.

postsynaptic terminal

where the neurotransmitters are accepted in the dendrite of the receiving neuron

reuptake

when sending neurons reabsorbs extra neurotransmitters

excitatory neurotransmitters

increase the likelihood that a neuron will fire in an action potential

inhibitory neurotransmitters

decrease the likelihood a neuron will fire in an action potential

hyperpolarization

when the inside of a neuron becomes more negative, moving the neuron farther away from its threshold needed for action potential

Multiple Sclerosis

disorder that occurs when the myelin sheath is damaged, resulting in the disruption of the transmission of electrical signals. It leads to muscle weakness, fatigue, and coordination problems.

Myasthenia Gravis

autoimmune disorder that affects the communication between nerves and muscle. Antibodies block or destroy receptors, preventing muscle contraction and causing weakness/fatigue

Acetylcholine

a neurotransmitter that enables muscle action, learning, and helps with memory

Substance P

a neurotransmitter that helps in transmitting pain signals from the sensory nerves to CNS

Dopamine

a neurotransmitter that helps with movement, learning, attention, and emotions

Serotonin

a neurotransmitter that impacts hunger, sleep, arousal, and mood

Endorphins

a neurotransmitter that help with pain control and impact an individual’s pain tolerance.

Nonepinephrine

a neurotransmitter that increases your blood pressure, heart rate, alertness, and helps with the body’s fight or flight response

Glutamate

a neurotransmitter that helps with long term memory and learning

GABA

a neurotransmitter that helps with sleep, movement, and slows down nervous system

Endocrine system

a system that helps regulate different biological processes in the body.

Adrenaline

AKA epinephrine, a hormone that helps with the body’s response to high emotional situations and helps form memories

Leptin

a hormone that helps energy balance by inhibiting hunger. It signals to the brain that the body has enough stored fat, reducing appetite

Ghrelin

a hormone that signals to the brain that one is hungry and helps stimulate release of growth hormone

Melatonin

a hormone that is produced by the pineal gland in the brain and helps regulate sleep-wake cycle AKA circadian rythm

Oxytocin

a hormone that is produced in the hypothalamus and released by the pituitary gland. Promotes feelings of affection and emotional bonding

psychoactive drugs

purposefully alter an individual’s perception, consciousness, or mood

stimulants

drugs that excite and promote neural activities. give an individual energy, reduce appetite and cause them to become irritable. EX caffeine, nicotine, cocaine

depressants

drugs that reduce neural activity in an individual. cause drowsiness, muscle relaxation, lowered breathing. EX alcohol, sleeping pills

Hallucinogens

drugs that cause individuals to sense things that are not actually there. can reduce motivation and cause panic. EX marihuana, peyote, LSD.

opioids

drugs that function as a depressant but are very addictive. give an individual pain relief. EX morphine, heroin

Agonist drug

drugs that increase the effectiveness of neurotransmitters. Mimic neurotransmitters to enhance their effect EX anti-anxiety drugs that increase GABA

Antagonist drug

drugs that decrease the effectiveness of a neurotransmitter. Block them from being released or bind to postsynaptic receptors to block it from binding.