Control and Coordination

Plants and animals both show a control and coordination mechanism. In plants this done by sending chemical signals and brining about various types of movements (e.g. phototropic, chemotactic, thingmotactic, etc). Animals, specially the higher vertebrates show a gradual increase in the complexity of their control and coordination by giving both electrical and chemical singles. In this chapter now you will study about development of nervous system in different animal groups and details of the system in humans.

Describe in brief an account of disorders of the thyroid.

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Thyroid gland disorders manifest in three primary types: hypothyroidism, hyperthyroidism, and simple goitre. Hypothyroidism: Hypothyroidism results from a deficient secretion of thyroxine, leading to two distinct disorders: cretinism in children and myxoedema in adults. •Cretinism: Occurs in childhood, characterized by the retardation of physical and mental growth. •Myxoedema: Affects adults, also known as Gull’s disease, resulting in … Read more

Explain action of steroid hormones and proteinous hormones.

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Hormones exert their effects by acting on specific target organs or tissues with designated binding sites, known as hormone receptors. The mechanisms vary between steroid hormones and protein hormones. Steroid Hormones: 1. Lipid-soluble steroid hormones easily traverse the lipoproteinaceous plasma membrane. 2. Receptors for steroid hormones are located in the cytoplasm or nucleus. 3. The … Read more

Describe in brief, an account of disorders of adrenal gland.

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Adrenal cortical secretion disorders result from both insufficient and excessive production of adrenal cortex hormones. Addison’s diseases: Addison’s disease manifests through symptoms such as hypoglycemia, reduced body temperature, weakened heart function, low blood pressure, acidosis, decreased concentrations of sodium and potassium in the plasma, increased urinary loss of sodium and water, impaired kidney function, and … Read more

What is adenohypophysis? Name the homones secreted by it?

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1. The adenohypophysis constitutes the prominent anterior segment of the pituitary gland. 2. Originating from the embryonic ectoderm, it emerges as Rathke’s pouch, a small protrusion from the roof of the embryonic stomodaeum. 3. Comprising secretory cells with an epitheloid structure, the adenohypophysis carries out hormonal functions. 4. Rathke’s pouch undergoes development to form this … Read more

Explain the role of hypothalamus and pituitary as a coordinated unit in maintaining homeostasis?

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1. Homeostasis maintains a constant internal body environment, with negative feedback mechanisms playing a crucial role. 2. Excessive hormone secretion triggers inhibiting factors from the hypothalamus, leading to negative feedback that halts pituitary stimulating hormone production. 3. Hormone deficits prompt the release of specific factors, signaling the respective gland to maintain hormonal balance and homeostasis. … Read more

Write the names of hormones and the glands secreting them for the regulation of following functions. a. Growth of thyroid and secretion of thyroxine. b. Helps in relaxing pubic ligaments to facilitate easy birth of young ones. c. Stimulate intestinal glands to secrete interstinal juice. d. Controls calcium level in the blood e. Controls tubular absorption of water in kidneys. f. Urinary elimination of water. g. Sodium and potassium ion metabolism. h. Basal Metabolic rate. i. Uterine contraction. j. Heart beat and blood pressure. k. Secretion of growth hormone. l. Maturation of Graafian follicle.

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(a) Adenohypophysis releases TSH. (b) The degenerating corpus luteum of the ovary produces Relaxin. (c) Duodenal mucosa secretes Secretin. (d) Thyroid releases Calcitonin (hypocalcemic hormone), and parathyroid glands produce Parathormone(hypercalcemic hormone). (e) Hypothalamus releases ADH. (f) Atrial natriuretic factor is produced by the atria of the heart. (g) Aldosterone is synthesized by the adrenal cortex. … Read more

What will be the effect of thyroid gland atrophy on the human body?

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The thyroid gland’s atrophy causes a reduction in thyroid hormone secretion, leading to the development of hypothyroidism. Hyposecretion of thyroid hormone: Hypothyroidism occurs when the thyroid gland fails to produce and release an adequate amount of thyroid hormone into the body. a. Cretinism: Hypothyroidism, characterized by a deficiency in the production of the thyroid hormone … Read more

Krishna was going to school and on the way he saw a major bus accident. His heart beat increased and hands and feet become cold. Name the part of the nervous system that had a role to play in this reaction.

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Krishna’s symptoms were a result of the sympathetic nervous system activation during an emergency. The adrenal medulla cells release adrenaline and noradrenaline, directly affecting the heart’s pacemaker, leading to increased heart rate and associated symptoms—a typical fright reaction triggered by the sympathetic nervous system.

Explain the Reflex Pathway with the help of a neat labelled diagram.

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1. Receptor organs, such as the skin, eyes, tongue, nose, and ears, specialize in converting stimuli into impulses. 2. Sensory neurons transport these impulses from the receptors to the central nervous system, with their cell bodies in the dorsal root ganglion. 3. Motor neurons, located in the ventral horn of the spinal cord, convey motor … Read more