BIOLOGICAL BASES OF HUMAN BEHAVIOUR
BASIC PSYCHOLOGY 2
Every behaviour begins with biology. Our behaviours, as well as our thoughts and feelings, are produced by the actions of our brains, nerves, muscles, and glands.
Biosocial • The nature of psychology is biosocial. • It thrusts upon the behavioral events of human beings. • MAN CONSTANTLY INTERACTS WITH THE ENVIRONMENT 8
Biosocial • The nature of psychology is biosocial. • It thrusts upon the behavioral events of human beings. • MAN CONSTANTLY INTERACTS WITH THE ENVIRONMENT 9
• Man consistently engages in interaction with the environment. • Sensory nerve impulses are transducted to the brain • Brain sends motor impulses to the organs of response. • The effector organs produce a response which is called behaviuor. • This brain mediated receptor effector mechanisms which produce a behaviour is called physiological or biological basis of behaviour 10
11
12
GENES AND BEHAVOIUR • The development of human Human Chromosomes being…. Is the climax of all wonders -Conkun EG • Human beings with all these potentials have developed from tiny threads of life called Chromosomes • Gametic cells unite to form Zygote which contains 23 pairs of chromosomes 13
Chromosomes James Watson Francis Crick • Chromosomes contain DNA in them. Maurice Wilkins • James Watson Francis crick, and Maurice Wilkins studied extensively on DNA. • DNAs contain Genes which are the bearers of Heredity 14
• Genes are also called the Down’s “master code” Syndrome • They contain the blue Klinefelter’s print of life. Syndrome • Sometimes there will be 15 abnormalities in the number of Chromosomes leading to syndromes.
• During gamete formation meiotic division occurs. • During this process there is exchange genetic material. • In the Zygote the genes function in a chance selection method leading to Character difference in offsprings. 16
17
Sex determination • Sex determination is based on the ‘x’ or ‘Y’ sex chromosomes present in the sperm • The ovum contains two ‘X’ chromosomes as the sex chromosomes. • Sex of the child entirely depend on the chromosome of the sperm cell. 18
INHERITED STRUCTURES • Under the guidance of heredity, organisms living in a normal environment, undergoes a process of growth involving three major sets of structures . 1. The Nervous system 2. The Endocrine glands 3. The Muscles First two systems are intensively studied to understand the Biological bases of behavior 19
THE NERVOUS SYSTEM • Behavior of an organism involves the coordination of receptors, effectors and adjustors . • Nervous system plays the role of the adjustors. • So it is important to know nervous system in detail to understand more clearly about human behavior. 20
THE NERVOUS SYSTEM 21
22
Nerve Cell ◼ The basic structural and functional unit of the nervous system is called a nerve cell or neuron. ◼ Each nerve cell consists of a central portion containing the nucleus, known as the cell body, and one or more structures referred to as axons and dendrites. ◼ The dendrites are rather short extensions of the cell body and are involved in the reception of stimuli. ◼ The axon, by contrast, is usually a single elongated extension; it is especially important in the transmission of nerve impulses from the 23 region of the cell body to other cells.
24
Types of neurons ➢Sensory or Afferent neuron ➢Motor or efferent or efferent neuron ➢Interneuron or connector neuron 25
• Two types of phenomena are involved in processing nerve signals Electrical and Chemical • Electrical events propagate a signal within a neuron, and chemical processes transmit the signal from one neuron to another neuron or to a muscle cell. 26
All or none law states that if cell responds it responds fully provided the stimulus is just above the threshold value. 27
Synapse 28
Division of nervous system ➢1.PERIPHERAL NERVOUS SYSTEM. ➢2.CENTRAL NERVOUS SYSTEM. ➢3. AUTONOMIC NERVOUS SYSTEM 29
30
Central Nervous System -CNS. 31 The Central Nervous System is that part of the nervous system which lies within the bony case formed by the skull and the spine. The central nervous system, which includes the brain and spinal cord, processes and coordinates all incoming sensory information and outgoing motor commands, and it is also the seat of complex brain functions such as memory, intelligence, learning, and emotion. The brain and the spinal cord consists of this system.
THE SPINAL CORD ◼ It is that part of the Central neurons system which lies within the back bone . ◼ It is composed of the grey matter and the white matter. ◼ The grey matter consists of nerve cells nerve cells lying inside and the white matter consisting of nerve fibers lying outside completely covering the grey matter.. 32
◼ Spinal cords function is two fold. ◼ In the first place it functions as a channel of communication from the brain and to the brain. Secondly it works as an organ for effective reflex action. Spinal cord cross Spinal cord section 33
Reflex Action • Sudden involuntary response to stimulus is called reflex action • The stimulus response pass through a ‘reflex arc’ Reflexes Reflex arc 34
Reflex arch • Reflex arch is a simple nervous pathway connecting a receptor and an effector. It consists of the following parts • A) The receptors • (b) Afferent or sensory neuron • (c) Association neuron or interneuron • (d) Efferent or motor neuron • (e) Effector organ 35
36
Some examples of common human reflex actions • (a) Knee jerk reflexes • (b) Ankle jerk reflexes • (c) Blinking reflexes • (d) Sneezing reflexes • (e) Salivation or watering of mouth on sight, smell or thought of food. • (f) Withdrawal reflexes, viz. withdrawal of hand or finger on touching a hot plate surface etc. 37
STRUCTURE AND FUNCTION OF BRAIN AND SPINAL CORD 38
Structure of the brain For the convenience of study, the brain can be divided into three parts: Hindbrain, Midbrain and Forebrain. 40
Brain stem and cerebellum • Medulla • Pons • Cerebellum 41
THE MEDULLA OBLONGATA • The Medulla oblongata is a continuation of the brain on the one hand and a spinal cord on the other. • There fore its nerve tissues form a connection between the two paths of central nervous system. It is both a conductor as well as an integrating center. • It regulates the highly complex process like digestion, respiration and circulation which are necessary for preservation of life. 42
Pons – Provides pathways for sensory and motor impulses to and from hemispheres. – It also connects other parts of the brain with cerebrum and cerebellum It is believed that pons is involved in sleep mechanism, particularly the sleep characterised by dreaming. It contains nuclei affecting respiratory movement and facial expressions also. 43
THE MEDULLA OBLONGATA 44
CEREBELLUM • Cerebellum or hindbrain is situated behind and beneath the cerebrum. • It helps to maintain the equilibrium of the body and keeps it erect. • It also stores the memory of movement patterns so that we do not have to concentrate on how to walk, dance, or ride a bicycle. 45
Mid brain • Mid brain connects cerebellum with cerebrum. • Connected to the midbrain , there is a complex mass of network of nerve fibres. • This is called reticular activating system – RAS or ascending reticular activating system. • This is critically concerned with various degrees of arousal – from deep sleep to alert awareness e.g. the slight sound made by a sick child moving in bed may arouse his mother but the noise
• The mid brain is divided into two main parts: The roof or tectum : - superior colliculi – vision - inferior coliiculi - auditory The floor : provides connection between lower and higher centres of brain 47
48
Fore - brain • The higher centres of the brain is called fore brain. It includes : i. Thalamus ii. Hypothalamus iii. Limbic system iv. Cerebrum Brain basics Brain anatomy 49
Thalamus and Hypothalamus 50
Search
