Tamil Nadu Agricultural University
Agricultural College and Research Institute
Coimbatore-3
EXT 502 Applied Behaviour Change(2+1)
Biological Bases of Human Behaviour-nervous system,brain,endocrine system
and genes
INTRODUCTION
The biology of behaviour is the study of behavioural functions of the nervous
system,particularly the brain
‘Physiological psychology’ is the branch of psychology which seeks to determine how
activity in the nervous system is related to behaviour and the mind
Human behaviour involves the body-mind interaction of the various bodily factors.the
most important are:
1. The sense organs,called receptors
2. The muscles and endocrine glands called effectors
3. The nervous system known as the connecting or integrating mechanism
4.
Neurons
Neurons are the building blocks of the nervous system
Types of neurons:
1. Sensory neurons(afferent)-2 millions
a. Sends messages from sense organs –brain
2. Motor neurons(efferent)- 2-3million
a. sends messages from brain-muscles,glands,organs
3. Interneurons-billions &billions
a. relay messages between sensory and motor neurons
4. Glial cells-”the forgotten cell”
a. glue cells which help connections,insulate and clean up
Nervous system
Structurally and functionally divided into three divisions
1. CNS(Central Nervous System)located at the body region
2. PNS(Peripheral Nervous System)functionally peripheral
3. ANS(Autonomic Nervous System)functionally involuntary
NERVOUS SYSTEM-central nervous system
Brain
1. Forebrain-thalamus
i. hypothalamus
ii. limbic system
iii. cerebral cortex
2. Midbrain
3. Hindbrain-medulla
i. pons
ii. cerebellum
The forebrain
Its important structures are thalamus, hypothalamus,limbic system and the cerebrum
All sensory impulses pass through from thalamus to the higher centres
The thalamus has plays a role in the control of sleep and alertness
Hypothalamus
It lies below the thalamus
It exerts a key influence on all kind of emotional as well as motivational behaviour
Centers in the hypothalamus have control over the important body processes like
eating,drinking,sleeping and temperature control
The limbic system
It consists of structures in the thalamus,hypothalamus and 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
behaviour related to survival,memory,smell.pleasure and pain,rage and
aggression,affections,etc.
The cerebrum
It is most complex and largest part of brain
The cerebrum is covered by a thick layer of tightly packed neurons called the cerebral
cortex
It is divide into two hemispheres:the left and right hemispheres
The midbrain
It is concerned with the relaying of messages particularly those related to hearing and
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 consiously and which should be rejected
It is composed of three structures,the medulla,the pons and the cerebellum
medulla controls breathing and many important reflexes and it also regulates the
digestion,respiration and circulation
The pons assists in breathing,transmitting impulses from the cerebellum to the higher
brain regions
Cerebellum is responsible for body balance and the coordination of body movements like
dancing,typing,playing,etc.
Spinal cord
It works as a channel of communication from and 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
BRAIN
Functions of the brain
To identify
To organize
To interpret
To respond
Forebrain
The anterior and largest portion of the brain;includes the cerebral hemispheres,the limbic
system,the thalamus and hypothalamus,and the corpus callosum
Function:to control cognitive,sensory and motor function,and regulate
temperature,reproductive functions,eating,sleeping and the display of emotions
Midbrain
The midbrain is the smallest region of the brain that acts as relay station for auditory and
visual information
Portions of the midbrain called the red nucleus and the substantia nigra are involved in
the control of body movement
Hindbrain
The area of the brain comprising the pons,medulla and cerebellum
Function:to co-ordinate motor activity,posture,equillibrium and sleep patterns and
regulate unconscious but essential functions,such as breathing and blood circulation
Central core-the old brain which controls basic functions such as eating and is common to
all vertebrates
Cerebral cortex-the new brain responsible for the most sophisticated information
processing in the brain.it also contains four lobes
Four lobes of the brain
Frontal lobe
Lies in the motor cortex,involves in decision making,planning and carrying out
behaviour,responsible for the control of voluntary movements
Damage:inability of the good choices and recognized consequences
Can cause increase irritability
Change in mood and inability to regulate behaviour
Parietal lobe:
Involves in processing sensory information from the body,such as touching,locating
position of limbs,feeling temperature and pain
Damage:the ability to multitask is reduce or eliminated,recognition of right and left
Damage neglect
Temporal lobe:
Primary location of auditory area,involves in appreciation of sounds and spoken language
Responsible for learning,memory and hearing
Damage:inability to pay attention to what they see and hear
Inability to comprehend language
Impaired memory
Emotional disturbance
Prosopagnosia
Occipital lobe:
Involves in processing visual information,which includes seeing colours and perceiving
and recognizing objects,animals and people
Damage:lose of visual capability
Inability to identify colour
Hallucination
Brain and behaviour
The entire behaviour is effectively managed and controlled by the co-ordination and
functioning of the nervous system
How we will behave in a particular situation depends upon the judgement of our brain
The sense impressions,which are received through the sense organs,donot bear any
significance unless they are given a meaning by the nervous system
Levels of functioning
The individual functions at three levels:
Conscious level
Preconscious level
Unconscious level
Conscious level
It constitutes all those experience of whuch an individual is immediately aware of at any
particular time
It consists of his current thoughts and experiences
For example:attending to something,observing,thinking,reasoning,juding,imagining
Every conscious experience has three aspects cognitive,affective and conative or
knowing
Pre-conscious level
Pre-conscious thoughts are memories of whuch 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
For example:sometimes we forget a name in the course of conversation.we do not
become conscious of it,we make an effort and try to recollect,after sometime,the name
which we were in search of,springs all at once into consciousness
Unconscious level
Experience those which are not easily reached by our conscious thoughts as the pre-
conscious experiences
We are not aware of our unconscious functions and cannot understand them at any one
time
Unconscious experiences cannot become conscious but must be inferred from our
behaviour
For example:certain things make you very angry but you cannot understand why you
become so angry
Body-mind relationship
Psychology studies human behaviour which involves both body and the mind
They are interrelated and interact upon each other
Mental functions and physical states affect each other
Body and the mind are two aspects of the living,dynamic and adjusting personality
Mind is regarded as a function of the body;it does not exists apart from the body
It is some total of various mental process such as
observing,knowing,thinking,reasoning,feeling,imagining,remembering,judging and
others
Body-mind reationship-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 ones
personality,resulting in lethatgy,nervous tension,ect.
Effects of mental conditions on bodily functioning
Unpleasant emotions like fear,anger and worry cause irritability,insomnia,headache
ect.mental processes are intimately connected to brain or cortical prosesses
Emotions conflicts are responsible for peptic ulcer,ulcerative colitis etc.
Deep thinking and concentration can cause physical strain
ENDOCRINE SYSTEM
The endocrine system controls the way your body functions.it produces hormones that
travels to all parts of your body to maintain your tissues and organs.
A chemical communication network that sends messages throughout the body via the
blood stream
Here are the few areas governed by the endocrine gland
Reproduction
Responses to stress and injury
Body energy levels
Internal balance of body systems
Bone and muscle strength
Your endocrine system produces,stores and releases hormones.
Major endocrine glands and its functions
Hypothalamus-homeostasis
Pituitary gland-growth
Parathyroid gland-metabolic rate
Thyroid gland
Thymus-immune system
Adrenal gland
Pancreas-insulin and glucagon,controls sugar metabolism
Genesandbehaviour
the field of behavioural genetics
Behavioural genetics-the study of the influence of genetic factors on behavioural traits
Chromosomes-strands of DNA carrying genetic information
Human cells contain 46 chromosomes in pairs
Each chromosome-thousands of genes,also in pairs
Dominant,recessive
Homozygous,heterozygous
Genotype/phenotype andpolygenic inheritance
References:
Sharan B.Merriam,rosemary S.Caffarella,Raymond J.Wlodkowski,P.craton “Adult
Learning”Theories,Principles and Applications
https://en.m.wikibooks.org
www.ncbi.nlm.nih.gov
