CONTROL AND COORDINATION

Transcription

1 CONTROL AND COORDINATION INTRODUCTION The vital activities of life are controlled by endocrine system and nervous system. There are two types of coordination nervous coordination and hormonal coordination. In animals both hormones and neurons are involved in regulating and coordinating the various vital activities. In plants, only chemical phytohormones coordinate their behaviors environmental changes. INPORTANT TERMS AND CONCEPTS 1. Coordination. It is the process involved in various organs of an organism to work together in a systematic manner, so as to produce a proper reaction to the stimulus. 2. Stimulus. It is the change in the external or internal environment of an organism that provokes a physiological and behavioural response in the organism. 3. Response. It is the change of activity in an organism due to a stimulus. 4. Coordinates in plants. Plants respond to light, touch, gravitational force and other stimulus. The growth in plants in controlled by certain chemical substances known as plant hormones or phytohormones and the movement of plant in the direction of stimulus is known as tropism. Thus, the function of control and coordination in plants are regulated by both external and internal factors. The phytohormones and phytochromes together are invoked in the control and coordination between environment and plant responses. 5. Plant hormones or phytohormones. It can defined as a chemical substance which is produced naturally in plants and are capable of translocation and regulating one or more physiological processes when present in low concentration. Some hormones stimulate plant growth while others act as growth inhibitors; therefore plant hormones are also referred as growth regulators. 6. Types of phytohormones. There are five major types of plant hormones which are involved in the control and coordination in plants. These are as follows. (i) Auxins are the group of plant hormones produced from the root and shoot tips of the plant body. It promotes cell elongation, root formation, cell division, root formation, respiration and other physiological processes like protein synthesis, water uptake and protoplasmic permeability. Auxins also pay an important role in the development of seedless fruits. (ii) Gibberellins stimulate stem elongation, seed germination and flowering. The maximum concentration of gibberellins is found in fruits and seeds. (iii) Cytokinins are produced in dividing cells throughout the plant. In mature plants, cytokinins are produced in the root tips and are transported to the shoots. Cytokinins promote cell division and also help in breaking the dormancy of seeds and buds and regulate the phloem transport. Cytokinins delay the ageing in leaves and promote the opening of stomata. (iv) Abscisic Acid (ABA) is a growth inhibitor which reverses the growth promoting effects of auxins and gibberellins. It causes dormancy of seeds tubers and bulbs. It brings fall of leaves and fruits. It promotes the closing of stomata and is responsible for the loss of RNA, proteins and chlorophylls. (v) Ethylene is produced in the cells of higher plants, especially those under stress. It is produced by fruits, flowers seeds leaves and roots. Ethylene is a gaseous hormone which stimulates transverse growth It promotes ripening of fruits. It helps in breaking the dormancy of several plant organs. 7. Plant movements. The movements of the individual plant parts or organs of a plant like shoot, root, etc, are due to some external stimuli like light, force of gravity chemical substances, water etc. This movement of any part of a plant is a growth movement.

2 8. Types of plant movement. Plant response reflected in the form of movements may be of two types; (a) Tropic movements or tropism. It is the directional growth or movement of a plant organ in response to an external stimulus. Growth towards the stimulus is positive tropism and growth away from the stimulus is negative tropism. Tropic movements are classified as follows, depending on the type of stimulus causing it. (i) Phtotropism is the movement of a part of the plant in response to light. Shoots generally grow towards light and said to be positively phototropic while roots grow away from light and are said to be negatively phototropic. (ii) Geotropism is the movement of part of the plant in response to gravity. Roots are positively geotropic while shoots are negatively geotropic. (iii) Chemotorpism is the movement of a part of the plant in response to a chemical stimulus. If the plant part shows movement or growth towards the chemical, it is called positive is it called negative chemotropism. Fro example, the growth of pollen tube towards a chemical which is produced by an ovule during the process of fertilization in a flower. (b) Nastic movements. It is the movement of plant organs in response to external stimuli that are independent of the direction of the stimuli. Examples are the opening of evening primrose flowers at night (photonasty) and the folding up and drooping of leaves of the sensitive plant of touch-me-not (Mimosa pudica) when lightly touched (hyponasty). 9. Functions of plant hormones. The plant hormones regulate many functions in plants, which are as follows: (i) Germination of seeds or breaking the dormancy of seeds, (ii) Growth of root, stem and leaves. (iii) Flowering of plants (iv) Ripening of fruits, (v) Movement of stomata in leaves and (vi) Photoprism, geotropism, chemotropism and nastic movements 10. Photoperiodism. It is the response on an organism to changes in day-length or photoperiod on the developmental processes of a plant like germination of seeds and flowering. Photoperiodism is a kind of stimulus for plants. 11. Phytochrome. It is the protein based plant pigment present in small qualities in many plant organs. Phytochroe is responsible for making the plants sensitive of light effects. 12. Dormancy. It is the inactive period in the life of an animal or plant, during which growth slows or completely ceases. The physiological changes associated with dormancy helps the organism to survive adverse environment conditions. 13. Differentiation. It is the change from simple to more complex forms undergone by developing tissues and organs so that they becomes specialized for particular functions. Differentiation occurs during embryonic development, regeneration in animals and meristematic activity in plants. 14. Coordination in animals. Coordination of body functions in animals is effected by the endocrine glands and nervous system. The substances produces by endocrine glands are called hormones. Hormones are chemical messengers which are discharged in the blood by ductless or endocrine glands from where they reach different parts of the body. Endocrine glands are directly or indirectly controlled by the nervous system, which receives information about changes in the external environment in the form of stimuli. 15. Nervous system. It is the system of conducting tissues that receives the stimulus and transmits it to other parts of the body forming a network. Nervous system is most important for regulation, control and coordination of body function.

3 The nervous system comprises of neurons, nerves and nervous organs which controls, links and co ordinates the activities of different organs of the body. 16. Functions of the Nervous system: (i) It regulates involuntary actions. (ii) It controls and coordinates voluntary muscular activities. (iii) It keeps us informed about the outside world through the sense organs. (iv) It enables us to think, reason and remember. (v) It controls all the reflex actions in our body thus protecting it from harm. 17. Receptor. It is a cell or group of cells specialized to detect a particular stimulus and to initiate the transmission of impulses via the sensory nerves. The eyes, ears, nose, tongue and skin all contain specific receptors responding to external stimuli. There are five receptors or sense organ through which the animals receive stimuli or external information These receptors are photoreceptors for light (eyes), phonoreceptors for sound (ears), tangreceptors for taste (tongue), olfactoreceptors for smell (nose) and thigmoreceptors for touch (skin). The receptors pass information to the brain by a type of nerve cell called sensory neurons. Motor neurons transmit information from the brain to the effectors organs, mainly muscles and glands. 18. Nervous system in Hydra. Hydra belongs to phylum Cnidarians. It is a simple multi cellular animal. The nervous system of hydra consists of a network of nerve cells joined to one another and spread throughout its body. In hydra, the response to stimuli are effected and controlled by the nerve cells only. 19. Nervous System of an Insect. In higher invertible like insects the nervous system consist of bilobed nerve mass the brain, a long nerve cord and nerve ganglia. A long nerve cord runs along the body of the insect. The nerve cord has ganglia or masses of nerve cells at intervals along its entire length. The brain is present at the anterior end of the insect. 20. Ganglion. It is referred to a mass of nervous tissues containing many cell bodies and synapses, usually enclosed in a connective tissue sheath. 21. Control and coordination in Humans. There are two systems of coordination of activities in humans. These are Nervous system and Endocrine or Hormonal system. In human beings, nervous system and endocrine system work together to control and coordinate all activities such as our physical actions, thinking processes and emotional behavior. Both the systems of coordination, nervous and endocrine system consist of a number of organs working together in a systematic way. 23. The unit of Nervous : Neuron. The units which make up the nervous system are called nerve cells or neurons. So, neurons are the structural and functional unit of the nervous system. Neuron is the largest cell in the body. Neurons carry messages in the form of electrical signals called nerve impulses. Neuron is an elongated branched cell having three components-cell body, Dendrites and Axon. (i) Cell body or Cyton is like a typical cell containing a central nucleus and surrounding cytoplasm. Around the nucleus there are granules called Nissal granules. Stimulus is changed into impulse in the cyton. (ii) Dendrites are short and branched processes connected toe the cyton. They receive sensation or stimulus, which may be physical, chemical, mechanical or electrical. The simulates is passed onto cyton. (iii) Axon is the longest part of the neuron. It is a single, elongated fibre arising from one side of cyton. It conducts impulses away from the cell body. The plasma membrane of an axon is covered by a protective sheath of lipid and protein called myelin sheath, formed by the Schwann cells. It is broken into constrictions called the nodes of Ranvier. The axon endings are branched and are called synaptic terminals.

4 23. Synapse. It is the junction between two adjacent neurons or nerve cells, i.e., between the axon ending of one and the dendrites of the next. 24. Nerve impulse. It is the information in the form of chemical and electrical signals passing through neurons. These impulses are carried by dendrites towards the cell body. 25. Nervous. They are thread like yellowish white structure emerging from the central nervous system, i.e., the brain and the spinal cord. Depending on the functions, nerves are classified into: (i) Sensory. Nerves which can messages from sense organs to the central nervous system. (ii) Motor. Nerves which carry impulses from the central system to various sense organs. (iii) Mixed. Nerves which carry both sensory and motor fibers conduct nerve impulses in both the directions. 26. Human nervous system. Nervous system in man consists of three main parts: (i) Central Nervous System (CNS) includes the brain spinal cord. (ii) Peripheral Nervous System (PNS) comprises of the nerves arising from brain (cranial) and spinal cord (spinal); and (iii) Autonomic Nervous System (ANS) is the made up of parasympathetic and sympathetic nervous systems. ANS includes which connect the visceral receptors and effectors with the CNS but workd independently to regulate the involuntary movements. NERVOUS SYSTEM Central Nervous System Peripheral Nervous System Autonomic Nervous System (CNS) (PNS) (ANS) Brain Spinal Cord Cranial Nerves Spinal Nerves (12 pairs) (31 pairs) Fore Brain Mid Brain Hind Brain Sympathetic Parasympathetic Cerebrum Olfactory lobes Cerebellum Pons Medulla Oblongata 1. Occipital lobe 2. Temporal lobe 3. Frontal lobe 4. Parietal lobe 27. Central Nervous system. The CNS consists of the brain and the spinal cord. The brain and the spinal cord are protected by the skeleton brain by the cranium and spinal cord by the vertebral column. Both are surrounded by membrane of connective tissue called meninges. The space between the membranes is filled with a fluid called cerebrospinal fluid. The job of the central nervous system is to collect all the information from all the receptors in out body. BRAIN is the highest coordinating center in the body. The brain is broadly divided into three regions: fore brain, mid brain and hind brain. The fore brain receives impulses from the nasal organs. The mid brain receives impulses from the eyes, whereas the hind brain receives impulses from the ears and the skin. (A) Fore Brain includes cerebrum and olfactory lobes.

5 Cerebrum is the dome-shaped roof of the brain. It is the largest part of the brain. It is most important, complex and specialized part of the brain. Cerebrum is made of two cerebral hemispheres. Different areas of cerebrum have For example, the cerebrum has sensory areas where information is received from the sense organs called receptors. Similarly, cerebrum has motor areas from where instructions are sent to the various muscles of the body called effectors to do the various jobs. There are specific regions in cerebrum for each kind of stimulus and response. For example, (i) Occipital lobe is the region for sight, i.e,. visual reception. (ii) Temporal lobe is the region for hearing, i.e., auditory reception. (iii) Frontal lobe is the region for speech, facial muscular activities and higher mental activities. (iv) Parietal lobe is the region for taste, smell, touch, temperature and conscious association. (v) Olfactory lobes in the force brain lie the below the cerebrum. They contain olfactoreceptors which are the organs of smell. (B) Mid Brain connects the fore brain to hind brain. It controls reflex movements of the head, neck and truck in response to visual and auditory stimuli. It also controls the reflex movements of the eye muscles, changes in pupil size and shape of the eye lens. (C) Hind Brain consists of three centers called cerebellum, pons and medulla oblongata. Cerebellum lies at the roof of the hind brain. This region controls the coordination of body movements and posture. Pons lie just above the medulla and take part in regulating respiration. Medulla oblongata lies at the floor of the hind brain and continues into the spinal cord. It is the seat of involuntary activities which controls heart beat, breathing and blood pressure. It is also the regulating center for swallowing, coughing, sneezing and vomiting. SPINAL CORD is a cylindrical structure and a part of the central nervous system. It begins in continuation with medulla oblongata and extends downwards. It is enclosed in a bony cage called vertebral column. A total of thirty one pairs of spinal nerves arise from the spinal cord. 28. Functions of Spinal cord: Spinal cord is the main center of reflex action. It is concerned with the conduction of nerve impulses and forms the brain. 29. Functions of Brain: (i) The brain receives information carrying impulses from all the sensory organs of the body. (ii) The brain responds of the impulses brought in by sensory by sending its own instructions to the muscles and glands causing them to function accordingly. (iii) The brain correlates the bodily activities so that the mechanisms and chemical reations of the body work together efficiently. (iv) The brain coordinated the bodily activities so that the mechanisms and chemical reactions of the body work together efficiently. (v) The brain stores information so that behavior can be modified according to the past experience. This function makes brain the organ of thought and intelligence. 30. Electro Encephalogram (EEG). It is an instrument which can record the electrical activity of brain. EEG is used by the doctors to diagnose the brain ailment of a person. 31. Peripheral Nervous System constitutes the cranial and spinal nerves along with their branches. (i) Cranial nerves arise from the brain and spread throughout the head. There are twelve pairs of cranial nerves. They carry both sensory and motor neurons. (ii) Spinal Nerves arise from the spinal cord along most of its length and spread throughout the body.

6 There are 31 pairs of spinal nerves-eight in the neck region, twelve in chest region, five in abdominal region, five in hip region and one in the coccyx region. Coccyx is the last bone of the vertebral column. All nerves arising from spinal cord are mixed nerves they function both as sensory and motor nerves. The function of PNS is mainly to control the voluntary activities of the body. 32. Autonomic Nervous System (ANS) means self governing nervous system. Autonomic nervous system is called visceral nervous system. It lies outside and parallel to CNS. ANS consists of a pair of chains of nerves and ganglia found on both sides of the vertebral column. Many of the ganglia lie within the organs they control. ANS controls and regulates the functions of the internal organs of our body involuntarily. The autonomic nervous system can be classified anatomically and functionally into sympathetic and parasympathetic nervous system. The sympathetic nervous system acclerates the action and parasympathetic slows it down. Thus, these systems are antagonistic to each other. (a) Sympathetic Nervous System originates from the thoracic (chest) and lumber (abdominal) areas of the spinal cord. The main functions of sympathetic nervous system are: (i) Dilation of the pupil sympathetic nervous system are: (ii) Constriction of blood vessels of the skin and visceral organs. (iii) Accleration of heart beat. (iv) Stimulation of sweat glands. (v) Releases adrenaline. (vi) Dilates bronchi and bronchioles of lungs. (vii) Inhibition of muscles of various organs like stomach, urinary bladder, etc. Thus, sympathetic system prepares the body for violent action against abnormal conditions. (b) Parasympathetic nervous system originates from the brain and the lower region of the cord. The main functions of Parasympathetic nervous system are: (i) Constriction of the pupils of the eyes. (ii) Dilation of the blood vessels. (iii) Slowing of heart beat. (iv) Stimulation of muscles of the stomach and urinary bladder. (v) Increasing blood supply to the reproductive organs. (vi) Constricts bronchi and bronchioles of lungs. Thus, Parasympathetic nervous system is mainly concerned with re-establishing normal conditions after the violent act is over. 33. Reflex Action is defined as an unconscious, automatic and involuntary response of effectors, muscles and glands, to a stimulus, which is monitored through the spinal cord. Example: Knee-jerk reflex, movement of diaphragm, coughing, sneezing, yawning and blinking of eyes are all reflex actions. 34. Reflex Arc. It is the pathway taken by the nerve impulses and responses in a reflex action from the receptor organs like skin to the spinal cord and from the spinal cord to the effectors organs like muscles. The reflex arc pathway is shown in the flow chart as follows: 35. Hormones are the chemical substances which coordinate and control the activities of living organisms and also their growth. The term hormone was introduced by Bayllis and Starling. 36. Characteristics and Functions of Hormones: (i) Hormones are the secretions of endocrine glands or tissues. (ii) They are poured directly into the blood and carried throughout the body by blood circulatory system. 37. Endocrine glands are a structure or group of cells or tissue which manufacture hormones and secretes them directly into the bloodstream to act at distant sites in the body known as target organs or cells. They are ductless glands and are located at different parts of the body. They tend to control slow long-term activities in the body such as growth as sexual development.

7 The endocrine glands present in man includes hypotenuse, pituitary (hypophysis), pineal, thyroid, parathyroid, pancreas, adrenal, tests (in males) and ovaries (in females). Some endocrine glands like pancreas, tests and ovary perform dual functions both exocrine and endocrine functions. (i) Hypothalamus gland is present in the brain. It produces releasing hormones. It regulates the secretion of hormones from pituitary gland. (ii) Pituitary glands (Hypothesis) is present at the base of the brain. It is also known as the master gland as it controls the other endocrine glands. The pituitary gland secretes five hormones: Growth Hormone (GH) regulates the development of bones and muscles. Tropic hormones regulates the secretion of hormones from other endocrine glands like adrenal glands, thyroid gland, testes and ovaries. Prolactin hormone regulates the function of mammary glands in females. Vasopressing hormone regulates water and electrolyte balance in the body. Oxytocin hormone regulates the ejection of milk during lactation. Pineal gland is present in the brain near to the pituitary gland. It secretes melatonin hormone which inhibits ovarian growth and ovulation, thus reducing reproductive activities. (iii) Thyroid gland is present just below the neck. It secretes a hormone called thyroxin which regulates the metabolism of carbohydrates, fats and proteins in the body. (iv) Parathyroid glands are four in number, which are embedded in the thyroid gland. It secretes a hormones called Parathormone, which regulates calcium and phosphate levels in the blood. (v) Adrenal glands are two in number, which are located one on top of each kidney. Adrenal glands secrete two hormones-adrenalin and corticoids. The function of adrenalin and corticoid hormones is to regulate blood pressure, heart beat, breathing rate, carbohydrate metabolism and mineral balance. (vi) Pancreas is present just below the stomach in the body. It secretes two hormones-insulin and glucagons. The function of insulin hormone is to increase the blood glucose. The function of glucagons hormone is to increase the blood glucose. Pancreas is exocrine as well as endocrine gland. The endocrine part is called the islets of lengerhans. (vii) Tests in males are present outside the lower abdomen in scrotum. It secretes male sex hormones called testosterone. The function of testosterone hormone is to regulate male accessory sex organs and secondary sexual characters like moustache, beard and voice. (viii) Ovaries in female are present in the lower abdomen. It secretes two female sex hormones called estrogen and progesterone. The function of estrogen hormone is to regulate the development of female accessory sex organs and secondary sexual characters such as mammary glands, soft skin, hair pattern and feminine voice. The function of progesterone hormone is to control the uterus changes in menstrual cycle. It also helps in the maintenance of pregnancy. 1 MARK QUESTIONS 1. Sympathetic nervous system induces (a) Secretion of digestive system induces (b) Secretion of saliva (c) Increased heart beat (d) All of these 2. The junction between the axon of one neuron and the dendrite of the next is called (a) Constant bridge (b) A synapse

8 (c) A joint (d) Junction point 3. Why is oxytocin called as birth hormne? 4. Name two hormones of pancreatic islets. 5. Deficiency of which hormone lads to diabetes mellitus? 6. Which gland secretes glucagons? 7. Name the hormone that promotes motility of sperms. 8. Which part of the brain contains respiratory center? 9. Name the source glands of glucagons and parathormone. 10. Name the source glands of prolactin and estrogen. 11. Which hormone is known as birth hormone? 12. Name the endocrine part of pancreas. 13. Name one gland in human body which secretes digestive enzymes as well as hormones. 14. Name the hormone which induces milk secretion. 15. Name the organ which secretes progesterone. 16. Name the hormone that regulates calcium level in blood. 17. Mention the exact part of brain which controls the voluntary movements of muscles. 18. Name the hormone and its source, which produces changes in secondary sex organs in human females to prepare for anticipated pregnancy. 19. The plant hormone which is essential for cell division is (a) Ethylene (b) Auxin (c) Gibberellin (d) Cytokinin 20. The root of a plant is said to be (a) Positively geotropic (b) Positively phototropic (c) Negatively geotropic (d) Positively thigmotropic 21. Which of these plant hormones is a growth inhibitor? (a) Ethylene (b) Auxin (c) Abscisis acid (d) Cytokinin 22. Master gland of the body is (a) Testis (b) Pituitary (c) Thyroid (d) Adrenal 23. Which hormone brings about contraction of the uterine wall, leading to labour pain? (a) Extrogen (b) Progesterone (c) Relaxin (d) Oxytocin 24. People suffering from diabetes mellitus are unable to secrete (a) Insulin (b) Adrenaline (c) Thyroxin (d) Vasopressin 25. The seat of intelligence and voluntary actions in the brain is (a) Diencephalon (b) Cerebellum (c) Cerebrum (d) Medulla oblongata 26. The activities of the internal organs are controlled by the (a) Central nervous system (b) Peripheral nervous system (c) Autonomic nervous system (d) None of these 27. Which gland is lost as the age advances? (a) Thyroid (b) Thymus (c) Pancreas (d) Adrenal 28. The term hormone was coined by (a) Starling (b) Went (c) Yabuta (d) Wilson 29. The secretion of ductless gland is called Receptors are structure which are able to detect Coordinates in plants take place take place by means of chemical substances called...

9 32. Brain is located in the... cavity of skull. 33. Endocrine glands secrete their secretions in Name the hormone secreted by thymus gland. 35. Name the hormone secreted by the alpha cells of islets of Langerhans of Pancreas. 36. What is a neuron? 37. Name any two types of tropism. 38. Discuss phototropism. 39. What is a ganglion? 40. Write the functions of any one part of hind brain. 41. Define phytohormones. 42. What are phytochromes? 43. Give the function of growth hormone. 44. Define synapse. 45. What happens when as impulse travel through a neuron? 46. What is the function of medulla oblongata? 47. Taking the example of heart beat justify the antagonistic action of the sympathetic and the parasympathetic nerves. 48. Which two endocrine glands perform dual functions? 49. How many cranial nerves are present in a mammal? 50. What are mixed nerves? 51. How many spinal nerves are present in man? 52. What is the basic function of a receptor? 53. Name the hormones that control the metabolism of calcium and phosphorus. 54. Mention the function of fore brain. 55. What is parthenocarpy? 56. Name two growth promoting hormones in plants. 57. Define photoperiodism. 58. Define nastic movement. 59. What is tropic movement? 60. Name the pigment present in plant which perceives light stimulus. 61. Give one example of chemotropism. 62. Name the endocrine gland which is present just above the heart. 63. Name the full names of PNS and CNS. 64. Name the endocrine gland which is four lobed. 65. Name the largest and second largest part of the brain. 66. Mention the various components of hind brain. 67. Name the part of the brain which controls equilibrium and posture of the body. 68. Name the reflex center of the brain. 69. Name the structural and functional unit of nervous system. 70. What is BMR? 71. Name sex hormones. 72. Write the functions of cerebral hemisphere. 73. Name the growth regulator found in plants. 74. Why does a person suffer from diabetes? 75. Expand ABA. 76. Give one important function of gibberellin. 77. What is seed dormancy? 78. Give the role of cytokinin in plants. 79. Which plant growth regulator is found in the form of gas? 80. Name the growth regulator which promotes stem elongation. 81. Explain the position of pituitary gland.

10 82. Where is glucagon secreted? What is its function? 83. Define geotropism. 84. Name the plant which shows nastic movement. 85. Name the pigment which responds to light duration. 86. Which growth hormone is present in the tip of stem? 87. Name the hormone which causes stem elongation and leaf expansion. 88. Which hormone is used for artificial ripening of fleshy fruits? 89. Define hormones. 90. Name the gland which is exocrine as well as endocrine. 91. Which hormone deficiency causes dwarfism? 92. Which hormone is released during child birth? 93. What is the function of calcitonin? 94. Which is known as emergency gland? 95. What is the function of testosterone? 96. Nam the temporary structure in female which is endocrine in nature. 97. Which organs constitute CNS? 98. What is the function of cerebrospinal fluid? 99. What is the function of cerebellum? 100. What is central canal? 101. What is the significance of reflex action? 102. Name the fluid that is found between the meninges Which part of the brain is concerned with memory, will and power? 104. What is sensory and motor nerve? 105. What is receptor? 106. What are endocrine glands? 107. List various endocrine glands What is the function of glucagons? 109. What is the function of insulin? 110. Name the male sex hormone Name the female sex hormone Name the two systems that control and coordinate all other systems in human body Name the three divisions of human nervous system Give the functions of oxytocin hormone Name the connective tissue covering of the brain Mention the source gland of thyroxine What are the major divisions of the fore brain Name the major lobes of cerebral hemisphere Give two functions of spinal cord Name the part of brain which is a center of perception of visual secretion Which part of brain act as a center of sensation of taste and smell? 122. Which part of brain act as a center of sensation of pitch and loudness of sound? 123. Which part of brain act as a center for balance of the body? 124. What is the study of hormones called? 125. Name the glands which secrete estrogen and progesterone Give the function of parathormone What is a reflex arc? 128. Give two examples of reflex actions performed in our daily life Name the place of the human body where largest number of neurons arc found What is the chemical nature of hormone? 131. Name some common functions of nervous and Endocrine system Name the part of the brain which is concerned with muscular.

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