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 51
Hypothalamus It regulates physiological processes involved in emotional and motivational behaviour, such as eating, drinking, temperature regulation, and sexual arousal. It also regulates and controls the internal environment of the body (e.g., heart rate, blood pressure, temperature) and regulates the secretion of hormones from various endocrine glands. 52
Thalamus It is like a relay station that receives all incoming sensory signals from sense organs and sends them to appropriate parts of the cortex for processing. It also receives all outgoing motor signals coming from the cortex and sends them to appropriate parts of the body. 53
Limbic system The limbic system is a group of brain structures that play a role in emotion, memory, and motivation. For example, electrical stimulation of the amygdala in laboratory animals can provoke fear, anger, and aggression. The hypothalamus regulates hunger, thirst, sleep, body temperature, sexual drive, and other functions. 54
CEREBRUM • CEREBRUM IS DIVIDED INTO:- 55
1. Controls voluntary movements and actions such as eating ,talking walking etc. 2. Motor control, higher level cognitive activities, proper co- ordination of psychomotor activities. 3. Conscious process such as thinking, planning, decision making, pursuing goals etc. 4. Damage to frontal lobe adversely affects behavior , personality and intellect 56
1) Coordinates sensory and motor output. 2) Speech 3) Comprehending and coordinating stimuli at tridimensional level . 4) Activities relating to touch sensation. 57
1) Auditory sensation 2) Processing of auditory information such as sound words etc. 3) Storage of verbal and visual memory. 58
1) Receiving nerve impulses from visual receptors. 2) Interpreting of visual impulses. 3) Memory for visual stimuli and colour orientation 59
PERIPHERAL NERVOUS SYTEM- Autonomic Nervous System • Autonomic Nervous System, in vertebrate anatomy, one of the two main divisions of the nervous system, supplying impulses to the body's heart muscles, smooth muscles, and glands. 60
• Two antagonistic divisions make up the autonomic nervous system: 1. the sympathetic, or thoracicolumbar, division, which stimulates the heart, dilates the bronchi, contracts the arteries, and inhibits the digestive system, preparing the organism for physical action. 2. The parasympathetic, or craniosacral, division, which has the opposite effects, and prepares the organism for feeding, digestion, and rest 61
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The major Neurotransmitters and their functions 64
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DUCTLESS GLANDS OR ENDOCRINE GLANDS • There are several glands in our body, which secrete several bodily chemicals both internally as well as externally. • They can be grouped into two distinct categories namely • duct glands and ductless glands or endocrine glands. 70
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Endocrine system 72
Anterior , intermediate and Posterior lobes of pituitary
Pituitary Gland The pituitary gland secretes the growth hormone and many other hormones, which direct and regulate the secretions of many other endocrine glands found in our body. This is why the pituitary gland is known as the “master gland”. 74
Some hormones are secreted at a steady rate throughout life, while others are secreted at an appropriate time in life. For example, the growth hormone is released steadily through childhood, with some spurt during adolescence, while gonadotropic hormones are secreted at the age of puberty, which stimulates the secretion of appropriate sex hormones among boys and girls. As a result, primary and secondary sexual changes take place. 75
Thyroid Gland It produces thyroxin that influences the body's metabolic rate. The steady secretion of this hormone maintains the production of energy, consumption of oxygen and elimination of wastes in body cells. On the other hand, underproduction of thyroxin leads to physical and psychological lethargy. 76
The steady secretion of this hormone maintains the production of energy, consumption of oxygen and elimination of wastes in body cells. On the other hand, underproduction of thyroxin leads to physical and psychological lethargy. 77
Adrenal Gland This gland is located above each kidney. It has two parts, adrenal cortex and adrenal medulla, 78
The adrenal cortex produces three groups of steroid hormones from cholesterol. They are collectively called adrenocorticocoids (corticosteroids, corticoids). They are: • glucocorticoids • mineralocorticoids • sex hormones (androgens).
Glucocorticoids Cortisol (hydrocortisone), is the main glucocorticoid but small amounts of corticosterone and cortisone are also produced. They are essential for life, regulating metabolism and responses to stress. Secretion is controlled through a negative feedback system involving the hypothalamus and anterior pituitary.
Mineralocorticoids (aldosterone) • Aldosterone is the main mineralocorticoid. • Its functions are associated with the maintenance of water and electrolytebalance in the body.
Sex hormones • Sex hormones secreted by the adrenal cortex are mainly • androgens (male sex hormones) and the amounts produced • are insignificant compared with those secreted by the testes and ovaries in late puberty and adulthood
The medulla is completely surrounded by the adrenal cortex. It is stimulated by its extensive sympathetic nerve supply to produce the hormones adrenaline (epinephrine) and noradrenaline (norepinephrine).
Adrenaline (epinephrine) and noradrenaline (norepinephrine) Together they potentiate the fight or flight response by: • increasing heart rate • increasing blood pressure • diverting blood to essential organs including the heart, brain and skeletal muscles by dilating their blood vessels and constricting those of less essential organs, such as the skin • increasing metabolic rate • dilating the pupils
Adrenaline has a greater effect on the heart and metabolic processes whereas noradrenaline has more influence on blood vessels
Gonads Gonads refer to testes in males and ovaries in females The hormones secreted by these glands control and regulate sexual Behaviours and reproductive functions of males and females. 86
The normal functioning of all hormones is crucial to our behavioural well-being. Without a balanced secretion of hormones, the body would be unable to maintain the state of internal equilibrium. Without the increased secretion of hormones during the times of stress, we would not be able to react effectively to potential dangers in our environment. Finally, without the secretion of hormones at specific times in our lives, we would not be able to grow, mature and reproduce 87
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• A slight imbalance of these glands causes restlessness, anxiety and weakness. • Our physical strength, morale thinking and reasoning power and decision-making ability – all depend upon the health of the glands. • In short, these glands are found to play a dominant role in the life of a person. • Without their proper functioning a man or woman finds difficulty in leading a happy normal life. 91
NERVOUS SYSTEM AND PERSONALITY DEVELOPMENT • Our behaviour to a great extend is controlled by our nervous system. • How we will behave in a particular situation depends upon the judgment of our brain. 92
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