Pages in book: Psychologie omvat de studie van mentale activiteit en gedrag. Een
psycholoog probeert het gedrag van mensen te begrijpen en te voorspellen. Psychological
science = the study, through research of mind, brain and behaviour. Not simply about
intuitions or common sense -> often wrong. Psychology is the scientific study of mind, brain
and behaviour
- Mind = mental activity. Perceptual experiences (sight etc), memories, thoughts and
feelings. Mental activity results from biological processes within the brain
- Behavior= totality of observable human (or animal) actions.
Psychological science teaches critical thinking = systematically questioning and evaluating
information using well-supported evidence.
- How to separate the believable from the incredible, how to spot poorly designed
experiment, develop the skills necessary to critically evaluate claims.
- Amiable scepticism = openness and wariness. Begin open to new ideas but carefully
considering the evidence.
- Looking for holes in evidence, using logic and reasoning to see whether the
information makes sense, and considering alternative explanations.
Psychological science helps us understand biased or inaccurate thinking. Most of the biases
occur because we are motivated to use our intelligence. Our minds are constantly analysing
all the information we receive and trying to make sense of it. These attempts generally result
in relevant and correct conclusions. But sometimes we see patterns that do not exist. Often,
we see what we expect to see and fail to notice things that do not fit with our expectations.
Important because: false beliefs can sometimes lead to dangerous actions.
• Distinguish between the two basic divisions of the nervous system.
• Distinguish between the functions of distinct types of neurons.
• Describe the structu re of the neuron.
• Describe the electrical and chemical changes that occur when neurons communicate.
• Identify the major neurotransmitters and their primary functions . ! kennen + werking
central nervous system (CNS) =The brain and the spinal cord.
peripheral nervous system (PNS) = All nerve cells in the body that are not part of the central
nervous system.
The nervous system's response to the world around us is responsible for everything we
think, feel, or do. The CNS and PNS are anatomically separate, but their functions are highly
interdependent. The PNS sends a variety of information to the CNS. The CNS organizes and
evaluates that information and then directs the PNS to perform specific behaviors or make
bodily adjustments.
Complex networks of neurons sending and receiving signals are the functional basis of all
psychological activity. Each neuron communicates SELECTIVELY with tens of thousands of
other neurons to form circuits, or neuron networks. These networks develop through
genetic influence, maturation and experience, and repeated firing. In other words, alliances
form among groups of neurons.
The somatic component of the PNS is involved in voluntary behavior. The autonomic
component of the PNS is responsible for the less voluntary actions of your body,such as
controlling heart rate.
,Reception phase: neurons take in the chemical signals from neighbouring neurons. During
integration, incoming signals are assessed. During transmission, neurons pass their own
signals to yet other receiving neurons.
Sensory neurons: detect information from the physical world and pass that information
along to the brain, usually through the spinal cord. The sensory nerves that provide
information from the skin and muscles are called somatosensory nerves.
motor neurons direct muscles to contract or relax, thereby producing movement.
Our reflexes, automatic motor responses, occur before we even think about those
responses. For each reflex action, a handful of neurons simply convert sensation into action.
Neurons = the basic units of the nervous system; cells that receive, integrate, and transmit
information in the nervous system . They operate through electrical impulses, communicate
with other neurons through chemical signals, and form neural networks. Bestaat uit:
dendrite, cell body, axon, and terminal buttons.
dendrites = detect information from other neurons.
cell body = where information from thousands of other neurons is collected and integrated.
axon = by which information is conducted from the cell body to the terminal buttons. Vary
tremendously in length. A nerve is a bundle of axons that carry information between the
brain and other specific locations in the body.
terminal buttons= at the ends of axons, small nodules that release chemical signals from the
neuron into the synapse.
synapse The gap between the terminal buttons of a "sending" neuron and the dendrites of a
"receiving" neuron;
Messages are received by the dendrites, processed in the cell body, transmitted along the
axon, and sent to other neurons via chemical substances released from the terminal buttons
across the synapse
The outer surface of a neuron is a membrane, fatty hydrophobic barrier, semipermeable. On
membranes ion channels.
,action potential =The electrical signal that passes along the axon and subsequently causes
the release of chemicals from the terminal buttons. An action potential, also called neural
firing. Action Potentials Produce Neural Communication
resting membrane potential = The electrical charge of a neuron when it is not active.
-70 mV = resting potential. The electrical charge inside the neuron is slightly more negative
than the electrical charge outside – typically -70 millivolts . When a neuron has more
negative ions inside than outside, the neuron is described as being polarized. The polarized
state of the resting neuron creates the electrical energy necessary to power the firing of the
neuron.
Sodium channels and potassium channels. Partially as a result of this selective permeability
of the cell membrane, more potassium than sodium is inside the neuron. Another
mechanism in the membrane that contributes to polarization is the sodium-potassium
pump. This pump increases potassium and decreases sodium inside the neuron, activity that
helps maintain the resting membrane potential.
Changes in electrical potential lead to action. Excitatory signals depolarize the cell mem-
brane (i.e., decrease polarization by decreasing the negative charge inside the cell). Through
depolarization, these signals increase the likelihood that the neuron will fire. Inhibitory
signals hyperpolarize the cell (i.e., increase polarization by increasing the negative charge
inside the cell). Through hyperpolarization, these signals decrease the likelihood that the
neuron will fire.
If the total amount of excitatory input surpasses the neuron's firing threshold (- 55
millivolts), an action potential is generated. Sometimes only a few sodium ions enter the
cells. Dus dan might slightly decrease to -60 mV ofzo, maar nothing happens. Action
potential is only generated if somewhere along the membrane potential difference exceeds
the excitation threshold.
The action potential is an electrical ripple that travels down the axon. Because the neuron
has been depolarized, ions can move freely. When a neuron fires, these sodium gates in the
cell membrane open. The open gates allow sodium ions to rush into the neuron. A fraction
of a second later, potassium channels open to allow the potassium ions inside the cell
membrane to rush out.
Action potentials spread along the axon. Electrical signals travel quickly because of fatty
myelin sheath = a fatty material, made up of glial cells (= glia) , that insulates some axons to
allow for faster movement of electrical impulses along the axon net als plastic omhulsel van
draden. Nodes of Ranvier= small gaps of exposed axon, between the segments of myelin
sheath, where action potentials take place.
Because of the insulation provided by the myelin sheath, the action potential skips quickly
along the axon. It is recharged at each node along the axon. Since the myelin insulation helps
messages move quickly along axons, demyelination slows down neural impulses.
All-or-none principle: when a neuron fires, it fires with the same potency each time; a
neuron either fires or not - it cannot partially fire, although the frequency of firing can vary.
If the sum of excitatory and inhibitory signals leads to a positive change in voltage that
exceeds the neuron's firing threshold, an action potential is generated. Intensity variations
by: -variations in the number of neurons firing, and -variations in firing rate.
, The stronger the stimulation, the more frequently the neuron fires action potentials. so
when a neuron is depolarized past its firing threshold, an action potential occurs, i.e. the
neuron fires.
The neuron that sends the signal is called the presynaptic neuron, and the one that receives
the signal is called the postsynaptic neuron. Inside each terminal button are
neurotransmitters (made in the axon) stored in vesicles. neurotransmitters = Chemical
substances that transmit signals from one neuron to another. Action potentials cause
vesicles to fuse to the presynaptic membrane and release their contents into the synapse.
Receptors= In neurons, specialized protein molecules on the postsynaptic membrane;
neurotransmitters bind to these molecules after passing across the synapse. A
neurotransmitter can bind only with its particular type of receptor, each receptor can be
influenced by only one type of neurotransmitter (lock-and-key model)
After an action potential travels to the terminal button, it causes the vesicles to attach to the
presynaptic membrane and release their neurotransmitters into the synapse. These
neurotransmitters then travel across the synapse and attach themselves or bind to receptors
on the postsynaptic neuron. The binding of a neurotransmitter with a receptor can cause
ion channels to open or close more tightly, producing an excitatory or an inhibitory signal in
the postsynaptic neuron. An excitatory signal encourages the neuron to fire. An inhibitory
signal discourages it from firing.
inhibitory: hyperpolarization occurs: potential difference
becomes larger.
once a neurotransmitter is released into the synapse, it continues to bind with receptors and
continues to exert an inhibitory or excitatory effect. It also blocks new signals until its
influence is terminated.
The three major events that terminate the neurotransmitter's influence in the synapse are
reuptake, enzyme deactivation, and reception.
Reuptake = The process whereby a neurotransmitter is taken back into the presynaptic
terminal buttons, thereby stopping its activity. (Recycling)
enzyme deactivation occurs when an enzyme destroys neurotransmitter in the synapse.
Different enzymes break down different neurotransmitters. Deactivate neurotransmitters.
Autoreception = neurotransmitters bind with receptors on the presynaptic neuron
Autoreceptors monitor how much neurotransmitter has been released into the synapse.
When an excess is detected, the autoreceptors signal the presynaptic neuron to stop
releasing the neurotransmitter
All neurotransmitters have excitatory or inhibitory effects on action potentials. The receptor
always has a specific response, either excitatory or inhibitory. The same neurotransmitter
can send excitatory or inhibitory postsynaptic signals, depending on the particular receptor's
properties. Any neurotransmitter can be excitatory or inhibitory.
