PYC1501-Basic Psychology EXAM PREP 2022. PYC1501 EXAM PREP
Chapters Number of questions
Human nervous
system
10
States of
consciousness
5
Sensation and
perception
5
Cognition 8
Intelligence and
creativity
2
Learning and memory 10
Emotion 6
Personality 4
2
Human nervous system
IM...
Chapters Number of questions
Human nervous 10
system
States of 5
consciousness
Sensation and 5
perception
Cognition 8
Intelligence and 2
creativity
Learning and memory 10
Emotion 6
Personality 4
, 2
Human nervous system
IMPULSE CONDUCTION IN THE HUMAN NERVOUS SYSTEM
Parts of a neuron
Dendrites: look like tree roots, receive messages from other neurons and surround the cell body
Cell body: also called the soma. It receives and sends messages in the form of new impulses
Cell nucleus: control centre of the cell; it controls all metabolic activities
Axon: carries messages from the soma. It is a thin fibre that differs in length
Myelin: white fatty sheath insulating the axon. It conducts much faster than un-myelinated axons.
Multiple sclerosis is the effect of axons that aren’t properly myelinated, as it attacks the myelin
Axon terminals: also called telodendria. Axon terminals branch out from the axon and end in small
knobs, called boutons (buttons in French).
Vesicles: tiny containers in the boutons which are filled with neurotransmitters
Neurotransmitters: chemical substances that play an important role in the conduction of a
message from one neuron to the next
Types of neurons
Sensory/afferent: carry messages from the environment to the brain/spinal cord. Info is detected
by the senses. This info can also come from the organs in the body
Motor/efferent: conduct messages from the spinal cord/brain to the muscles and glands
Nerve tract: bundle of axons in the brain/spinal cord
Nerve: bundle of nerves outside the brain and spinal cord
Process of impulse conduction
Stimulus is a form of energy received by the senses and converted into a form of energy
understandable to the nervous system. Impulse conduction is the basic form of sending info in the
nervous system. Two main processes:
• Electrical – nerve impulse begins in the first segment of the axon and travels down the axon to
the terminals because of electrical events at the cell membrane
, 3
• Chemical – the passage of the nerve impulse from one axon to another. There is a small gap
between the axon terminals of one neuron and the dendrites of another and the chemical process
will determine whether it reaches it or not
Nerve impulse: each neuron is like a tiny battery that stores potential energy. The fluid inside and
outside the cell contains small chemical particles called ions that are electrically charged. Some
are positive and some are negative. There are more positive ions on the outside of the cell and
more negative ones on the inside and they naturally constantly move from an area of high
concentration to an area of low concentration. Also, opposites attract and like repel.
Resting membrane potential: condition of readiness before an impulse can fire. It is an electrical
charge brought about by the difference between the positive and negative ions inside and outside
the cell. The neuron is ready to receive or conduct impulses
Action potential: messages arriving from other neurons alter the resting potential. If the resting
potential changes enough the cell reaches a threshold or critical point. Each neuron has a different
threshold and the stimulus has to be intense enough to exceed the threshold and change the
resting potential into action potential. In this way the structure of the axon membrane changes: tiny
openings in the cell membrane allow ions from the outside of the cell to move inside. These
channels first open near the soma and then sweep along the length of the axon as the action
potential (and thus the impulse) sweeps along.
Refractory period: immediately after an impulse has been conducted, the neuron is not ready to
send another message until the resting potential has been restored. Two types of refractory
periods:
• Absolute – no impulse can be generated
• Relative – an impulse can be generated but only with very intense stiulus
Refractory periods ensure that stimulus only travel one way and also prevent over-stimulation
Characteristics of impulse conduction: ‘all or nothing’ event. The stimulus is either strong enough
to result in impulse conduction or it isn’t. the strength of the stimulus does not change the strength
or speed of the impulse.
• Strength + speed: the strength + speed of impulse conduction is constant within a particular
neuron but it can vary with nerve fibres of different sizes. The larger the fibre, the stronger and
faster the impulse can be conducted.
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