Control And Coordination

Sensory neurons are the neurons that carry impulses from receptor to the brain where the sensation is interpreted. Sensory neurons are afferent neurons since they take the sensation towards brain or spinal cord (CNS).

Spinal cord is a part of the central nervous system that is housed inside the vertebral column. It is an extension of the brain and is responsible for reflex actions. Spinal cord receives impulses from the sense organs and controls body responses.

The spinal cord is protected by vertebrae and meninges (protective membranes) around it. The cerebrospinal fluid fills the spaces between these meninges and acts as a cushion thereby protecting the spinal cord and also the brain.

The brain and spinal cord are considered as central nervous system because CNS is located centrally where the brain is housed in the cranium and spinal cord in the vertebral column. Both, the brain and spinal cord are covered by meninges and surrounded by cerebrospinal fluid. The brain and spinal cord are the integrating and control centres therefore they are considered as central nervous system.

Hypothalamus, found in the diencephalon part of the brain, maintains homeostasis by regulating the body temperature, blood pressure and heart rate. It is the master control of the autonomic system. It also regulates secretion of hormones from the pituitary gland, hunger, thirst, body weight, sleep etc.

The hormone that controls the basal metabolism is thyroxine. It’s source gland is the thyroid gland. Thyroxine also brings about balanced growth, improves oxygen uptake, increases heart rate, regulates body temperature etc.

Hypothalamus of the nervous system is integrated with endocrine system via the pituitary gland. It sends signals to pituitary glands if any condition needs to be corrected. The hypothalamus itself acts as an endocrine organ by releasing the hormones ADH and oxytocin into circulation at neurohypophysis. Hypothalamus contains autonomic centres which have direct control over the adrenal gland.

the hormone that controls the water balance in the body is anti-diuretic hormone (ADH). The hormone is synthesized by hypothalamus and secreted by the posterior pituitary.

The hormone that controls the electrolyte balance in the body is Aldosterone. It acts to regulate sodium levels inside the body by increasing active reabsorption of sodium. It is synthesized by zona glomerulosa cells of adrenal cortex in adrenal gland.

Both the hormones, ADH and Aldosterone increase reabsorption of water in kidney.

Plant stems are positively phototropic while plant roots are negatively phototropic. Plant stems are negatively geotropic while plant roots are positively geotropic. Therefore, stem and root show unilateral growth towards light and gravity of earth respectively. The growth hormone like auxin, plays a major role in bringing such tropic movements. When a plant receives light, auxin in stem cause cell elongation and therefore stem grows upwards toward light. In the root, auxin build up in the cells of upper surface of root that induces re-orientation of the cell walls and the root grows downwards i.e., towards earth.

Auxins are the plant growth hormones that control the growing parts of the plant, stimulate cell elongation, differentiation of xylem and phloem, fruit development, apical dominance etc. They are synthesized at the tips of roots and shoot in the plant body. Auxin also influence plant responses to phototropism and geotropism.

Auxins are the plant growth hormones that control the growing parts of the plant, stimulate cell elongation, differentiation of xylem and phloem, fruit development, apical dominance etc.

Auxins influence gibberellins that promote cell elongation and thus increases plant length. They increase the distance between nodes thus spacing the branch points. Auxins control seedling orientation and always move away from light and downward due to gravity. In areas, where auxin is highly concentrated, cell growth is more. Auxin when applied, also stimulate root branching by initiating roots at the cut stem.

The statement that “Pancreas are the overall controller of the blood glucose level” is correct. The islets of Langerhans in the pancreas monitor the level of blood glucose level. The beta cells of islets of Langerhans produce insulin and release it when the blood glucose levels are high. The release of insulin promotes glucose uptake in cells. The liver also takes up glucose and stores it as glycogen. When the blood glucose level declines to normal point, the release of insulin is stopped.

The alpha cells of islets of Langerhans produce glucagon and release it when the blood glucose levels are low. The release of glucagon causes the liver to break glycogen and release it as glucose in blood. When the blood glucose level increases to normal point, the release of glucagon is stopped.

Control and coordination in animal body takes place through the action central nervous system and endocrine system. The nervous system controls all bodily activities and responses. It is made up of central nervous system which comprises the brain and spinal cord, and peripheral nervous system which is made up of nerves leading into and out of the central nervous system. The nervous system works by neurons which transmit information in the form of nerve impulses.

The endocrine system coordinates body activities by means of chemical substances called hormones. These hormones bring growth and development in the body and help to regulate extracellular fluid, metabolism, contraction of cardiac and smooth muscles, glandular secretions etc in the body.

The endocrine system coordinates our body activities by means of chemical substances called hormones. For example- Growth Hormone secreted by the pituitary gland stimulates the growth of muscles and bones in body. Adrenaline secreted from the adrenal gland helps the body to fight in emergency situations. Few of its effects on the body are- more energy, increased physical strength, raised blood pressure, releases sugar in the liver etc.

No. Since the case of swollen neck is slowly spreading every month, it seems more likely to be a disease and not any curse.

(b) The reason behind swollen necks of the young children in the village is swelling of the lymph nodes which occurs when there is some infection in the lymph nodes. The condition is called Lymphadenitis and it occurs when the child is suffering rom some respiratory infection or has cold. The problem can be overcome by giving the children antibiotics to fight the infection (if caused by bacteria) and medicines to reduce the swelling.

(c) The villagers need to be educated to make them free from blind faith. They need to understand that they cannot have blind faith in anything that does not have evidence. Education is the only weapon that can make people free from believing in blind faith and superstitions.

(d) Shyam portrays the image of a sensible man who seems to be educated and does not believes in anything that does not have evidence.