Biological basis of human behavior

BIOLOGICAL
BASIS OF
HUMAN
BEHAVIOR
Dr. Jayesh Patidar
www.drjayeshpatidar.blogspot.com

INTRODUCTION
• The biology of behavior is the study of behavioral
functions of the nervous system, particularly the
brain.
• „Physiological psychology‟ is that branch of
psychology which seeks to determine how activity in
the nervous system is related to behavior & the mind.
• Human behavior involves the body-mind interaction of
the various bodily factors. The most important are:
1. The sense organs, called receptors.
2. The muscles & endocrine glands called effectors
3. The nervous system known as the connecting or
integrating mechanism.
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RECEPTORS
• Behavior in all its forms &
shapes has definitely a
biological or physiological base.
• The behavior is based on the
various stimuli present in the
external environment & lying
within our body.
• The stimuli in the form of
various sensory experiences are
received by our sensory
systems known as receptors

• External receptors are those
sensory mechanisms that
help us make contact with the
outer world, for example,
eyes, ears, nose, tongue &
skin.
• The specific receptor cells for
receiving the external stimuli
lie within these sensory
systems.
External Receptors
RECEPTORS

• These receptors are associated
with the internal stimuli present in
our body.
• They are responsible for feelings
of pain, hunger or nausea.
• Another variety of these internal
receptors helps us in maintaining
balance, bodily posture &
equilibrium & also exercise
control over the muscle.
Internal Receptors
RECEPTORS

• Our sense organs help in
assimilating knowledge of the
world around us. Each of our
sense organs has a distinct
function to perform.
• Sense organs consist of
receptors, which are specialized
sensitive cells associated with
ending of sensory nerve fibers.
These receptors are stimulated
by objects outside the body &
also by internal conditions.
Sense Organs
RECEPTORS

• When the receptors
are not functioning
properly, they lead to
sensory defects or
disorders- visual,
auditory, cutaneous,
olfactory, gustatory,
kinaesthetic & static
disorders.
Sense Organs Count…
RECEPTORS

EFFECTORS
• Effectors are termed as the organs of responses.
• What is received through the sensory organs in
the form of sensory input is responded through
bodily reactions & motor activities carried out
through muscles & glands, particularly the
hormones secreted by the ductless gland which
are responsible for most of our behavior patterns.
• The under-activity or over-activity of these
glands, causes deficiency or excess of hormonal
secretion.
• This affects the entire personality make-up of the
individual.

• Our behavior & activity involves
movement of different parts of
our body.
• Muscles help the organism to
carry out motor activities in
order to respond to various
stimuli.
• There are mainly three types of
muscle – smooth muscles,
cardiac muscles & skeletal
muscles.
Muscles
EFFECTORS

• Glands play an important role in
human behavior.
• They also assist in the digestion
of food, elimination of waste
products, production &
prolongation of emotion states &
regulation of metabolism of the
body.
• There are two types of glands:
1. Duct glands
2. Ductless or endocrine glands.
Glands
EFFECTORS

• The duct glands release their chemical
secretion through little ducts or tubes into the
body cavities or on the surface of the body.
Some of the duct glands are
Salivary glands
Gastric glands
Sweat glands
Lacrimal glands
Kidney
Sex glands
Glands Count…
EFFECTORS

• The ductless or endocrine glands secrete chemical
substances called hormones.
• The hormones are released into blood stream & are
carried to all parts of the body.
• They play a vital role in the determination of human
personality.
• They affect the development of the body, general
metabolism, mental development, development of
secondary sex characteristics & emotional behavior.
• The endocrine glands are:
Glands Count…
EFFECTORS
The pituitary
Thyroid
Parathyroid
Adrenals
Male sex glands or gonads
Pancreas

CONNECTORS
• Connectors or adjustors help in regulating,
controlling or coordinating the activities of
receptors & effectors
• The ability to play a piano drive a car or hit a
tennis ball depends on muscle co-
ordination.
• It is necessary for the body to provide
messages to the muscles to coordinate.
• These messages are passed through
specialized cells called neurons.

• A nerve cell with all its branches is
called a neuron.
• These are the basic elements of
the nervous system.
• A neuron has a nucleus, a cell
body & a cell membrane to
enclose the whole cell body called
dendrites.
• Their role is to receive message
through electrical impulses from
the sense organs or adjacent
neurons & carry them to the cell
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Neuron
CONNECTORS

• The messages from the cell body further travel
the length of a nerve fiber known as the axon.
• There are three types of neurons.
The sensory neurons – they help in the process
of sensation & perception.
The motor neurons – they are responsible for
physical movements & activation of glands.
The inter-neurons or association neurons – they
carry signals in the form of memories & thoughts
& add reflex or automatic activities.
Neuron Count…
CONNECTORS

• Neurons are the receivers & transmitters of
messages.
• These messages are always in the form of
electrochemical impulses.
• There is a fluid-filled space called the synapse
between the axon of the neuron & the receiving
dendrite of the next neurons.
• Enlargements of the axon endings of the
transmitting neurons called boutons, contain
neuro-transmitter chemicals which are stored in
small vesicles.
Neural Impulse
CONNECTORS

• Neurotransmitters are a particularly important link
between the nervous system & behavior.
• Deficiency or an excess of a neurotransmitter can
produce severe behavior disorders.
• Some major neurotransmitters are:
 Acetylcholine
 Glutamate
 Gama-amino butyric acid (GABA)
 Dopamine
 Serotonin
 endorphins
Neurotransmitters
CONNECTORS

NERVOUS SYSTEM
• The human nervous system can be divided
into two parts
Central Nervous
System
It constitutes of the
brain & spinal cord
Peripheral Nervous
System
It constitutes of the
somatic system &
autonomic system

NERVOUS SYSTEM
BRAIN
Forebrain
- Thalamus
- Hypothalamus
- Limbic system
- Cerebral cortex
Midbrain
Hindbrain
- Medulla
- Pons
Cerebellum
CENTRAL NERVOUS SYSTEM

NERVOUS SYSTEM
• It‟s important structures are
thalamus, hypothalamus,
limbic system & the
cerebrum.
• All sensory impulses pass
through from thalamus to the
higher centers.
• The thalamus has plays a
role in the control of sleep &
alertness.
The forebrain

NERVOUS SYSTEM
• It lies below the thalamus.
• It exerts a key influence on all
kind of emotional as well as
motivational behavior.
• Centers in the hypothalamus
have control over the important
body processes like eating,
drinking, sleeping, temperature
control & sex.
Hypothalamus

NERVOUS SYSTEM
• It consists of structures in the
thalamus, hypothalamus &
cerebrum which form a ring
around the lower part of the
forebrain.
• The limbic system often called the
emotional brain, functions in
emotional aspects of behavior
related to survival, memory, smell,
pleasure & pain, rage &
aggression, affections, sexual
desire etc.
The limbic system

NERVOUS SYSTEM
• It is most complex & largest part
of the brain.
• The cerebrum is covered by a
thick layer of tightly packed
neurons called the cerebral
cortex.
• It is divided into two
hemispheres; the left & right
hemispheres.
The Cerebrum

NERVOUS SYSTEM
• It is concerned with the relaying of
messages particularly those related to
hearing & sight to higher brain centers.
• One of its important structures is known as
Reticular Activating System (RAS).
• With the help of this structure an individual
is able to decide which impulses should be
registered consciously & which should be
rejected.
The midbrain

NERVOUS SYSTEM
• It is composed of three structures, the medulla, the
pons & the cerebellum.
• Medulla controls breathing & many important
reflexes & it also regulates the digestion, respiration
& circulation.
• The pons assists in breathing, transmitting impulses
from the cerebellum to the higher brain regions.
• Cerebellum is responsible for body balance & the
coordination of body movements like dancing,
typing, playing, etc.
The midbrain

NERVOUS SYSTEM
• It works as a channel of communication from
& to the brain.
• It is a rope like structure made up of long
round nerve fibers.
• It also works as an organ for effective reflex
actions like withdrawal of the hand when
something is hot.
• These reflex actions are almost automatic in
nature.
Spinal Cord

NERVOUS SYSTEM
Localization of mental functions in the brain

NERVOUS SYSTEM
PERIPHERAL NERVOUS SYSTEM
Peripheral Nervous System
Made up of long axons & dendrites, it contains all
parts of the nervous system other than the brain
& spinal cord
Somatic division
(Voluntary)
Parasympathetic division
Acts to clam the body after an emergency
situation has engaged the sympathetic
division, provides a means for the body to
maintain storage of energy sources.
Automatic division
(Involuntary)
Acts to prepare the body in stressful
emergency situations, engaging
resources to respond to a threat
Sympathetic division

BRAIN AND BEHAVIOR
• The entire behavior is effectively managed &
controlled by the co-ordination & functioning
of the nervous system.
• How we will behave in a particular situation
depends upon the judgment of our brain.
• The sense impressions, which are received
through the sense organs, do not bear any
significance unless they are given a meaning
by the nervous system.

Integrative function of the Nervous System
Localization of mental functions in the brain
BRAIN AND BEHAVIOR

Importance of knowledge of the nervous system
& glands to a nurse
BRAIN AND BEHAVIOR
• It helps the nurse to understand the physiological
basis of patient behavior.
• It helps the nurse to understand how glandular
secretions influence personality.
• It helps the nurse to understand the various
diseases of nervous system & glands & their
effects on human behavior.
• It helps the nurse in understanding the process
of attainment of knowledge & learning, by
knowing this she can make desirable changes.

LEVELS OF FUNCTIONING
• The individual functions at three levels:
1. Conscious level
2. Preconscious level
3. Unconscious level

1. Conscious Level
BRAIN AND BEHAVIOR
• It constitutes all those experiences of which an
individual is immediately aware of at any
particular time.
• It consists of his current thoughts & experiences.
• For example; attending to something, observing,
thinking, reasoning, judging, imagining.
• Every conscious experience has three aspects
cognitive, affective & conative or knowing

2. Pre-conscious Level
BRAIN AND BEHAVIOR
• Pre-conscious thoughts are memories of which
an individual may not be aware of, but can recall
to mind when he wishes.
• Pre-conscious mental process are also called
subconscious mental process.
• Foe example; sometimes we forget a name in
the course of a conversation. We do not become
conscious of it, we make an effort & try to
recollect, after sometime, the name which we
were in search of, springs all at once into
consciousness.

3. Unconscious Level
BRAIN AND BEHAVIOR
• Experiences those which are not easily reached
by our conscious thoughts as the pre-conscious
experiences.
• We are not aware of our unconscious functions &
cannot understand them at any one time.
• Unconscious experiences cannot become
conscious but must be inferred from our
behavior.
• For example; certain things make you very angry
but you cannot understand why you become so
angry

BODY-MIND RELATIONSHIP
• Psychology studies human behavior which
involves both body & the mind.
• They are interrelated & interact upon each other.
• Mental functions & physical states affect each
other.
• Body & the mind are two aspects of the living,
dynamic & adjusting personality.
• Mind is regarded as a function of the body; it does
not exist apart from the body.
• It is some total of various mental process such as
observing, knowing, thinking, reasoning, feeling,
imagining, remembering, judging & others.

Modulation Process in Health and Illness
Effects of bodily conditions on mental functioning
• Increased blood pressure causes mental
excitement.
• Severe pain reduces the concentration level
• Chronic illness causes depression
• Malfunctioning of the endocrine glands for
example, may exert a full influence on one‟s
personality, resulting in lethargy, nervous
tension, etc.

Modulation Process in Health and Illness
Effects of mental conditions on bodily functioning
• Unpleasant emotions like fear, anger & worry
cause irritability, insomnia, headache etc. mental
processes are intimately connected to brain or
cortical processes.
• Emotional conflicts are responsible for peptic
ulcer, ulcerative colitis etc.
• Deep thinking & concentration can cause
physical strain.

Heredity
• Heredity is considered as “the sum total of inborn
individual traits”.
• Biologically, it has been defined as “the sum total
of traits potentially present in the fertilized ovum”.
• According to Douglas & Holland “one‟s heredity
consists of all the structures, physical
characteristics, functions or capacities derived
from parents, other ancestry or species”.
HEREDITY AND ENVIORNMENT

Heredity
• Heredity is the basis for the development of
human personality.
• Many aspects of human behavior & development
ranging from physical characteristics such as
height, weight, eye & skin color, the complex
patterns of social & intellectual behavior are
influenced by person‟s genetic endowment.
Genetics and Behavior

Environment
• The child inherits the traits & characteristics of
his parents & forefathers through genes at the
time of conception.
• After conception, how he develops is the
outcome of the interaction between his heredity
& environment.
• Environment covers the social, moral,
economical, political, physical & intellectual
factors which influence the development of the
individual from time to tiem.

Environment
• The environment is every thing that affects the
individual except his genes.
- (Boring, Langfield and Weld)
• Environment covers all the outside factors that
have acted on the individual since he began life.
- (Woodworth)
Definition

Environment
1. Intercellular environment: It relates to embryonic
development.
2. Intrauterine environment: It shelters the baby
during prenatal life.
3. External environment: It divided into three kinds:
a) Physical environment
b) Biological environment
c) Psychosocial environment
Types of Environment

Thank You

Biological basis of human behavior

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