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Introduction to Psychology

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Introduction to Psychology ­PSY101
Lesson 12
Central Nervous System (CNS) and Peripheral Nervous System (PNS)
The brain and its constituent parts are the most complex system ever known. With one trillion separate
cells, each one in a continuous process of changing in response to chemical signals. From the moment of
conception to the moment of death, the biology of the individual is changing. It is in this complexity that
our species has found the capability to store the accumulated experience of thousands of generations ­ to
create human culture. Our language, religions, governments, childrearing practices, technologies, economies
are all man-made; yet all depend upon the remarkable capacity of the brain to make internal representations
of the external world.
Biological Bases of Behavior
The Nervous System
Endocrine Glands
The Nervous system
The system that controls and regulates the structure and function of the brain, spinal cord,
nerves, and the nerve cells; it maintains coordination between the nervous system and the rest
of the bodily systems.
It is responsible for the internal communication system that ensures the integrated functioning
of the various systems.
Some Interesting Facts about the Nervous system
The nervous system consists of billions of highly specialized nerve cells called neurons.
Nerve impulse is an electrical impulse that travels along the nerves at a speed of around
400km/ hour.
Every second, a number of these impulses can pass along nerves.
Brain cells never re grow; once destroyed or dead, they can not be replaced.
Nerve fibers are very thin and fine in size; a hundred of them lying side by side would fit into
just 1mm.
The brain is divided into two visible parts or hemispheres; the left hemisphere controls the
right side of the body, and the right controls the left side.
The total surface area of the cerebral cortex is approximately 2.5sq.ft. if you spread it flat.
A nervous system cell is constituted in
such a way that it is specialized in receiving,
information to other cells.
Structure of a Neuron
·  Dendrites: Receivers of incoming
signals; branch fibers extending
Myelin Sheath
outward from the cell body.
·  Soma: The cell body containing
the cytoplasm and the nucleus of
(transmitting end)
the cell; cytoplasm keeps it alive.
Terminal Buttons
·  Axon: The nerve impulses travel
from the soma to the terminal buttons through the extended fiber of a neuron i.e., axon.
Introduction to Psychology ­PSY101
Terminal Buttons: Swollen, bulblike structures at one end of the axon; the neuron stimulates
the nearby glands, muscles, or other neurons
Connection between nerve cells
Synapse: the gap between one neuron and the other.
Synaptic Transmission: the procedure through which information is relayed from one
neuron to another across the synaptic gap.
Neurotransmitters: The post synaptic neuron is stimulated by the chemical messages released
from neurons; they cross the synapse from one neuron to another.
The Chemical Messages
The neurons follow an all-or-none law.... either a neuron will be firing or resting /off.
Excitatory Message: The chemical message that makes it more likely that the receiving
neuron will fire and the action potential will travel down its axon.
Inhibitory Message: The chemical message that inhibits a receiving neuron from firing so
that the action potential does not travel down its axon.
Major Varieties of Neurons
Sensory Neurons (afferent): they carry messages toward the Central Nervous System from
the sensory receptor cells.
Motor Neurons (efferent): they carry messages away from the Central Nervous System
toward the muscles and glands.
Inter-Neurons: they relay messages from sensory neurons to other inter-neurons and/or to
motor neurons.
Main Parts of the Nervous System
The Peripheral Nervous System
The Central Nervous System
Divisions of The Nervous System
Central Nervous System
Spinal Cord
The Peripheral Nervous System
The part of the
Peripheral Nervous System
nervous system that
Sensory Neurons
Motor Neurons
includes all parts of
the nervous system
except the brain and the
spinal cord
Somatic Division
Autonomic Division
(motor nerves to skeletal
(motor nerves to glands,
i. Somatic
Smooth & cardiac muscles
Division  /
Somatic  Nervous
System/ SNS
ii. Autonomic  division  /  Autonomic
Nervous System
Nervous System
Nervous System/ ANS
Somatic Division: controls the voluntary movements of the skeletal muscles.
Autonomic division: controls the involuntary movements all over the body; movements of the heart,
lungs, stomach, glands and other organs.
Introduction to Psychology ­PSY101
Central Nervous System (CNS)
Brain receives the information from all over the body (primarily in terms of stimulation via
sensation), interprets it, and decides how to respond.
The brain's function is similar to that of a computer; there is a central processing unit (CPU),
the output comes in, and the CPU analyses it and responds to it.
The Brain
The center of the nervous system.
The vital organ that is responsible for the
Spinal Cord
functions of seeing, hearing, smelling,
tasting, thinking, feeling, remembering,
speaking, dreaming, information processing,
and a lot more.
The regulator of basic survival
functions such as breathing, resting
and feeding.
It is responsible for abstract level
functions such as decision making, foresight, and problem solving.
The spinal cord is an information highway connecting the PNS to the brain.
Information travels to and from the brain by way of spinal cord.
Functions of the Various Structures of the Brain
Regulation of the internal systems
Adaptation to the varying environmental demands
Structure of Brain
The deeply grooved structure lies safely and securely in our skull.
The average adult human brain weighs 1.3 to 1.4 kg (approx. 3 pounds).
If you look at it from the outside the brain is pinkish gray in color; soft, spongy, and mottled.
The brain contains billions of nerve cells (neurons) and trillions of "support cells".
Parts of the Brain
The brain is made of three main parts:
a.  Fore brain
b.  Mid brain
c.  Hind brain
Fore Brain
i.  Cerebrum
ii. Thalamus
iii. Hypothalamus
iv. Limbic system
Mid Brain
i.  Tectum
ii. Tegmentum
iii. Reticular formation
iv. Substantia nigra
Introduction to Psychology ­PSY101
Hind Brain
i.  Cerebellum
ii. Pons
iii. Medulla oblongata
Brain Stem and Cerebellum
Located underneath the limbic system the brain stem, containing four structures, is found in all vertebrates.
It contains four structures:
1.  Medulla
2.  Pons
3.  Reticular formation
4.  Thalamus
o  Responsible for basic survival functions such as breathing, heartbeat, and blood pressure.
Medulla/ Medulla Oblongata
·  Located at the top of the spinal cord and continuous with it.
·  Damage to Medulla can be fatal as it is the center responsible for vital functions i.e.,
respiration, heart beat, and blood pressure.
·  Contains ascending & descending tracts that communicate between the spinal cord &
various parts of the brain.
·  At medulla, nerves ascending from the body and descending from the brain cross over;
hence the left side of the body is connected to the right side of the brain and vice versa.
·  Contains 3 vital centers:
Cardio inhibitory center: regulates heart rate.
Respiratory center: regulates the basic rhythm of breathing.
Vasomotor center: regulates the diameter of blood vessels.
2. Pons
Pons = Latin word for bridge
·  Bridge connecting spinal cord with brain and parts of brain with each other.
·  The pons seems to serve as a relay station carrying signals from various parts of the cerebral
cortex to the cerebellum.
·  Nerve impulses coming from the eyes, ears and touch receptors are sent on the cerebellum.
·  The pons also participates in the reflexes that regulate breathing.
·  It has parts that are important for the level of consciousness and for sleep.
3. Reticular Formation
·  The reticular formation is a region running through the middle of the hindbrain and into the
·  A dense network of nerve cells.
·  It keeps the brain alert even during sleep.
·  It makes the cerebral cortex attend to new stimulation by arousing it.
·  Long fibrous tracts of reticular formation run into the thalamus.
·  Needed for arousal from sleep & to maintain consciousness.
·  Serious damage to reticular formation may result into a coma.
4. Thalamus
The pair of egg-shaped structures located at the top of the brainstem.
·  Incoming sensory information is channeled to the appropriate area of the cerebral cortex by
thalamus, so that it is processed there.
·  Thalamus acts like a relay station.... the brain's sensory switchboard; it directs messages to the
sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla.
Introduction to Psychology ­PSY101
It receives information from the sensory neurons and routes it to the higher brain regions that
deal with vision, audition, taste and touch.
"Cerebellum" comes from the Latin word for "little brain". The cerebellum is located behind
the brain stem.
Cerebellum is somehow similar to the cerebral cortex: the cerebellum is divided into
hemispheres and has a cortex that surrounds these hemispheres.
It carries 10% of the weight of the brain.
It contains as many neurons as in the rest of the brain.
Its function is to coordinate body movements i.e. coordination, maintenance of posture &
Damage to cerebellum results into jerky and uncoordinated body movements.
Limbic System
Evolutionarily the structure of limbic system is rather old.
The limbic system, often referred to as the "emotional brain", is found buried within the
At the border of the brainstem and cerebral hemispheres it is a doughnut-shaped system of neural
structures; associated with emotions e.g. fear and aggression, and drives like hunger and sex; regulates
body temperature, blood sugar level and blood pressure.
Structures within the Limbic System
i. Hippocampus
ii. Amygdala
iii. Hypothalamus
·  Two almond-shaped neural clusters in the limbic system that are linked with emotions.
·  They are related with aggression and fear.
·  The hippocampus is the part of the limbic system that is important for memory and learning.
·  One of the smallest structures in the brain.
·  The neural structure lying below (hypo) the thalamus; Composed of several nuclei. Small
bundles of neurons that regulate physiological processes involved in motivated behavior e.g.
hunger, thirst, regulation of body temperature.
·  Hypothalamus acts as the body's Thermostat.
·  Helps govern the endocrine system via the pituitary gland.
·  Is linked to emotions.
Hypothalamus maintains the body's internal equilibrium e.g. looking for food when energy levels are low,
causing constriction of the blood vessels when body temperature falls.
Largest part of the human brain, associated with higher brain functions such as thought and
Occupies 2/3 of the brain's total mass
Consists of two symmetrical halves or hemispheres; The right cerebral hemisphere controls the
left side of the body and vice versa.
The hemispheres are connected by Corpus Callosum, a thick mass of nerve fibers.
Cerebrum regulates the brain's higher cognitive and emotional functions.
Introduction to Psychology ­PSY101
Cerebral Cortex
o  Coming from the Latin word for "bark", cortex means covering, or sheath; the cortex is a sheet of
tissue making up the outer layer of the brain.
o  About 1/10 of an inch in thickness, the cortex is composed of some 30 billion nerve cells and 300
trillion synaptic connections.
o  It is the body's ultimate control and information-processing center.
Sulci and Gyrus
o  The cerebral cortex is greatly convoluted in humans. These convolutions include:
1.  Sulci (singular Sulcus) i.e. small grooves.
2.  Gyri (singular Gyrus) i.e. large grooves also called "Fissures".
Grey matter
Cerebral cortex mostly consists of glia (glial cells), cell bodies, dendrites and
interconnecting neurons; they give the cerebral cortex a grayish brown appearance,
commonly known as `Grey Matter".
White Matter
Beneath the cerebral cortex lie millions of axons that connect the neurons of the cerebral
cortex to those located elsewhere in the brain.
The large myelin gives tissue an opaque white appearance known as "White Matter".
Cerebral Lobes
a.  Frontal lobe
b.  Parietal lobe
c.  Temporal lobe
d.  Occipital lobe
·  Each lobe controls a different range of activities.
·  Each hemisphere is vertically divided by the central sulcus, a groove.
·  The lateral fissure, another groove divides each hemisphere horizontally.
a. Frontal lobe
Associated with motor control and cognitive activities; reasoning, planning, decision making, problem
solving, movement and speech (Broca's Area).
b. Parietal lobe
Associated with controlling incoming sensory information; thus affecting movement, orientation,
recognition, perception of stimuli.
c. Temporal lobe
Associated with perception and recognition of auditory stimuli, memory & speech.
Wernicke's area: concerned with the understanding of language is located here
d. Occipital lobe
Associated with visual processing.
o  The brain is enclosed in the cavity of skull or cranium consisting of eight hard bones; One frontal
bone, two parietal bones, two temporal bones, one occipital bone, one sphenoid bone, and one
ethmoid bone.
Table of Contents:
  1. WHAT IS PSYCHOLOGY?:Theoretical perspectives of psychology
  3. SCHOOLS OF THOUGHT:Biological Approach, Psychodynamic Approach
  4. PERSPECTIVE/MODEL/APPROACH:Narcosis, Chemotherapy
  5. THE PSYCHODYNAMIC APPROACH/ MODEL:Psychic Determinism, Preconscious
  6. BEHAVIORAL APPROACH:Behaviorist Analysis, Basic Terminology, Basic Terminology
  8. RESEARCH METHODS IN PSYCHOLOGY (I):Scientific Nature of Psychology
  9. RESEARCH METHODS IN PSYCHOLOGY (II):Experimental Research
  11. COGNITIVE DEVELOPMENT:Socio- Cultural Factor, The Individual and the Group
  12. NERVOUS SYSTEM (1):Biological Bases of Behavior, Terminal Buttons
  13. NERVOUS SYSTEM (2):Membranes of the Brain, Association Areas, Spinal Cord
  14. ENDOCRINE SYSTEM:Pineal Gland, Pituitary Gland, Dwarfism
  15. SENSATION:The Human Eye, Cornea, Sclera, Pupil, Iris, Lens
  16. HEARING (AUDITION) AND BALANCE:The Outer Ear, Auditory Canal
  17. PERCEPTION I:Max Wertheimer, Figure and Ground, Law of Closure
  18. PERCEPTION II:Depth Perception, Relative Height, Linear Perspective
  19. ALTERED STATES OF CONSCIOUSNESS:Electroencephalogram, Hypnosis
  20. LEARNING:Motor Learning, Problem Solving, Basic Terminology, Conditioning
  21. OPERANT CONDITIONING:Negative Rein forcer, Punishment, No reinforcement
  22. COGNITIVE APPROACH:Approach to Learning, Observational Learning
  23. MEMORY I:Functions of Memory, Encoding and Recoding, Retrieval
  24. MEMORY II:Long-Term Memory, Declarative Memory, Procedural Memory
  25. MEMORY III:Memory Disorders/Dysfunctions, Amnesia, Dementia
  26. SECONDARY/ LEARNT/ PSYCHOLOGICAL MOTIVES:Curiosity, Need for affiliation
  27. EMOTIONS I:Defining Emotions, Behavioral component, Cognitive component
  28. EMOTIONS II:Respiratory Changes, Pupillometrics, Glandular Responses
  29. COGNITION AND THINKING:Cognitive Psychology, Mental Images, Concepts
  31. PERSONALITY I:Definition of Personality, Theories of Personality
  32. PERSONALITY II:Surface traits, Source Traits, For learning theorists, Albert Bandura
  33. PERSONALITY III:Assessment of Personality, Interview, Behavioral Assessment
  34. INTELLIGENCE:The History of Measurement of Intelligence, Later Revisions
  35. PSYCHOPATHOLOGY:Plato, Aristotle, Asclepiades, In The Middle Ages
  36. ABNORMAL BEHAVIOR I:Medical Perspective, Psychodynamic Perspective
  37. ABNORMAL BEHAVIOR II:Hypochondriasis, Conversion Disorders, Causes include
  38. PSYCHOTHERAPY I:Psychotherapeutic Orientations, Clinical Psychologists
  39. PSYCHOTHERAPY II:Behavior Modification, Shaping, Humanistic Therapies
  40. POPULAR AREAS OF PSYCHOLOGY:ABC MODEL, Factors affecting attitude change
  41. HEALTH PSYCHOLOGY:Understanding Health, Observational Learning
  42. INDUSTRIAL/ORGANIZATIONAL PSYCHOLOGY:‘Hard’ Criteria and ‘Soft’ Criteria
  43. CONSUMER PSYCHOLOGY:Focus of Interest, Consumer Psychologist
  44. SPORT PSYCHOLOGY:Some Research Findings, Arousal level
  45. FORENSIC PSYCHOLOGY:Origin and History of Forensic Psychology