Download Neurons and Neurotransmitters

Neurons and
Neurotransmitters
UNIT 3A: BIOLOGICAL PSYCHOLOGY
The Basics
 Everything
psychological is simultaneously
biological
 How do understand itself
 How
does the brain organize and communicate
with itself?
 How does the brain process the information
needed?
 How do we remember certain things?
The Basics

A Brief History
 Plato:
Gave the idea for the brain’s shape
 Aristotle:
Believed the mind was in the heart
 Gall:
Believed that the bumps on the skull could reveal our
mental health
 Biological
psychologists: study the links between biological
activity and psychological events
 Neuroanatomy:
study of the parts and function of neurons
Neuron Types

Neurons: a nerve cell, which is the basic building block of
the nervous system
 Afferent
(Sensory) Neurons: neurons that carry incoming information
from the sensory receptors to the brain and spinal cord.
 Efferent
(Motor) Neurons: Neurons that carry outgoing information
from the brain and spinal cord to the muscles and glands.
 Interneurons:
Neurons within the brain and spinal cord that
communicate internally and intervene between the sensory inputs
and motor outputs
Parts of a Neuron

Dendrite: the root like extensions of a neuron’s cell body
that receive messages and conduct impulses toward the
cell body at the synapse

Cell Body (Soma): contains the nucleus and other parts
of the cell needed to sustain its life

Axon: the extension of a neuron, ending in branching
terminal buttons, through which messages pass to other
neurons
Parts of a Neuron

Myelin Sheath: A layer of fatty tissue segmentally
encasing the axon of a neuron that speeds neural
impulses

Terminal Buttons (Axon Terminal): the branched end of
the axon that contains neurotransmitters

Synapse: the space between the terminal buttons of one
neuron and the dendrites of the next neuron
Neural Communication

Neurons are so intricately interweaved, it is hard to see where one ends and another
begins

Sherrington noticed an interruption in neural pathways, and decided that there is gap
between neurons

Synapse: The junction between the axon tip of the sending neuron and the dendrite of
cell body of the receiving neuron. The tiny gap at this junction is called the synaptic gap
or synaptic cleft.

Neurotransmitters: Chemical messengers that cross the synaptic gaps between neurons.
When released by the sending neuron, neurotransmitters travel across the synapse and
bind to receptor sites on the receiving neuron’s dendrites, thereby influencing whether
that neuron will generate a neural impulse. Enable neurons to communicate.

Reuptake: A neurotransmitter’s reabsorption by the sending neuron
How Neurons Fire

Parts work in sequence

Neurons have slightly negative charge (negative ions in the cell, positive ions surround it)

Cell membrane is selectively permeable

Terminal Buttons from neuron are stimulated and release a neurotransmitter into the
synapse.

Neurotransmitters fit into receptor sites on the dendrites of the next neuron.

Enough neurotransmitters are received (threshold) the cell becomes permeable positive
ions rush in (change in charge rushes down the neuron to fire again).

Action Potential: neural impulse; a brief electrical charge that travels down an axon

Threshold: The level of stimulation required to trigger a neural impulse

All-or-nothing Principle: Neuron fires completely or it does not fire at all
Neurotransmitters
 Many
different neurotransmitters (chemicals used
to enable neurons to communicate)
 Excitatory:
 Inhibitory:
 Different
excite the next cell into firing
inhibit the next cell from firing
types of neurotransmitters in the synaptic gap
at any time. The amount and type determine if the
threshold will be met.
Neurotransmitters

Common Neurotransmitters:

Acetylcholine (ACH): Enables muscle action, learning, and memory (motor
movement)


Lack of ACH is associated with Alzheimer’s disease
Dopamine: Influences movement, learning, attention, and emotion (motor
movement and alertness)

Lack of dopamine is associated with Parkinson’s disease, and overabundance is
associated with schizophrenia

Serotonin: Affects mood, hunger, sleep, and arousal

Endorphins: Natural, opiate-like neurotransmitters linked to pain control

Involved in addiction
Neurotransmitters
 Norepinephrine:
 Linked
Helps control alertness and arousal
to depression (lack of)
 GABA
(gamma-aminobutyric acid): A major inhibitory
neurotransmitter
 Glutamate:
memory
 Drugs
A major excitatory neurotransmitter; involved in
and Chemicals can Alter Neurotransmission
The Nervous System

Nervous System: the body’s
speedy, electrochemical
communication network
 Central
nervous system (CNS):
the brain and spinal cord
 Brain:
enables our humanity
(thinking, feeling, and acting)
 Spinal
cord: information
highway connecting the PNS to
the brain
The Nervous System
 Peripheral
nervous system (pns): the sensory and motor
neurons that connect the central nervous system to the
rest of the body
 Autonomic
glands)
(controls self regulated action of internal organs and
 Sympathetic
(Arousing)
 Parasympathetic (calming)
 somatic(
 Nerves:
(controls voluntary movements f skeletal muscles
bundled axons that form neural “cables”
connecting the central nervous system with muscles,
glands, and sense organs
Reflexes

Reflexes work differently than other types of sensory and
muscle movements.
 Reflex


stimulation ends in the spine (doesn’t reach the brain until after)
Examples
 Just
below your kneecap, your leg will jerk
 Hot
or Cold makes you jerk away from that object
Reflexes occur as a way to help prevent harm to ourselves,
thus it has adaptive value (help us survive so it is passed on)