Chemical Coordination and Integration – CBSE NCERT Study Resources

We studied that insulin (from pancreatic β-cells) lowers blood glucose by promoting glycogen synthesis, while glucagon (from α-cells) raises it via glycogenolysis.

• Insulin deficiency causes Type 1 diabetes (autoimmune β-cell destruction).
• Glucagon excess in Type 2 diabetes worsens hyperglycemia (NCERT Fig. 22.4).

Our textbook shows that 8.7% of Indian adults have diabetes (ICMR 2019), proving hormonal regulation's clinical significance.

Steroid hormones (e.g., cortisol) diffuse into cells and bind nuclear receptors, while peptide hormones (e.g., insulin) use membrane receptors.

• Cortisol alters gene transcription (slow action).
• Insulin triggers rapid GLUT4 translocation (NCERT Pg. 331).

This explains why steroid treatments take days but insulin injections work within minutes, crucial for therapy design.

Hypothalamus secretes releasing/inhibiting hormones (TRH, GHRH) into hypophyseal portal veins controlling pituitary tropic hormones.

• TRH stimulates TSH release (NCERT Fig. 22.2).
• Dopamine inhibits prolactin.

Disruptions here cause disorders like gigantism, showing the system's precision.

Stress activates the HPA axis: Hypothalamus (CRH) → Pituitary (ACTH) → Adrenal cortex (cortisol).

• Cortisol increases blood glucose (adaptive).
• Chronic stress causes hypertension (NCERT Pg. 336).

WHO reports stress-related illnesses rose 25% post-pandemic, validating this pathway's clinical relevance.

Thyroid regulation involves negative feedback: High T3/T4 inhibits TRH and TSH (NCERT Fig. 22.3).

• Graves' disease has autoantibodies mimicking TSH, causing hyperthyroidism.
• Patients show exophthalmos and weight loss.

This explains why 1.2% Indians have thyroid disorders (ICMR 2021), emphasizing feedback importance.

Melatonin from pineal gland regulates sleep-wake cycles via light-dark signals through the SCN.

• Peaks at night (9 PM-3 AM).
• Blue light from screens suppresses secretion (NCERT Pg. 338).

Studies show 68% teens have delayed sleep phase due to gadgets, proving melatonin's sensitivity to environmental cues.

We studied that insulin (from pancreatic β-cells) lowers blood glucose by promoting glycogen synthesis, while glucagon (from α-cells) raises it via glycogenolysis.

• Insulin deficiency causes hyperglycemia, as seen in Type 1 diabetes.
• Glucagon excess exacerbates high glucose, worsening diabetes symptoms.

Our textbook shows that autoimmune destruction of β-cells (Type 1) or insulin resistance (Type 2) disrupts this balance.

Research focuses on artificial pancreas systems to mimic hormonal regulation.

The hypothalamus releases TRH, stimulating pituitary TSH, which triggers thyroid hormone (T3/T4) secretion. High T3/T4 inhibits TRH/TSH via negative feedback.

• Hypothyroidism (low T3/T4) causes weight gain, as seen in Hashimoto’s disease.
• Hyperthyroidism (excess T3/T4) leads to Graves’ disease with weight loss.

Our textbook highlights iodine deficiency as a major disruptor of this axis.

Gene therapy is being explored to correct thyroid dysregulation.

Steroid hormones (e.g., cortisol) are lipid-soluble and act via intracellular receptors, while peptide hormones (e.g., insulin) bind surface receptors triggering secondary messengers.

• Cortisol alters gene transcription directly, whereas insulin activates tyrosine kinase cascades.
• Steroids have slower but longer-lasting effects compared to peptides.

Our textbook shows solubility differences dictate their pathways.

Hybrid drugs combining both mechanisms are under trial for metabolic disorders.

Adrenaline, secreted by adrenal medulla, activates sympathetic responses like increased heart rate and pupil dilation via β-adrenergic receptors.

• It redirects blood to muscles (vasodilation) and away from digestion (vasoconstriction).
• Liver glycogenolysis provides instant glucose, as shown in NCERT diagrams.

Chronic stress can deplete adrenal reserves, leading to fatigue.

Beta-blockers are used to counteract excessive adrenaline effects.

Melatonin, from the pineal gland, regulates sleep-wake cycles by responding to light-dark signals via the hypothalamus.

• Jet lag occurs due to mismatched melatonin secretion across time zones.
• Blue light from screens suppresses melatonin, delaying sleep onset.

Our textbook links low melatonin to insomnia and seasonal affective disorder.

Research explores melatonin analogs for shift workers.

PTH raises blood calcium by stimulating osteoclasts and renal reabsorption, while calcitonin (from thyroid) lowers it by inhibiting osteoclasts.

• Hyperparathyroidism causes brittle bones (osteoporosis).
• Calcitonin deficiency is linked to Paget’s disease.

NCERT highlights vitamin D’s role in aiding PTH function.

Bisphosphonates are used to mimic calcitonin’s effects.

The thyroid gland secretes two primary hormones: thyroxine (T4) and triiodothyronine (T3), which play a crucial role in regulating the body's metabolic rate. These hormones influence almost every cell in the body by:

• Enhancing oxygen consumption and heat production (calorigenic effect).
• Promoting growth and development, especially in the nervous system and bones.
• Regulating carbohydrate, protein, and fat metabolism to maintain energy balance.

Disorders due to thyroid malfunction include:

• Hypothyroidism: Caused by insufficient hormone secretion, leading to weight gain, fatigue, and cold intolerance. Severe cases in children cause cretinism (stunted growth).
• Hyperthyroidism: Excessive hormone production causes weight loss, anxiety, and increased heart rate (e.g., Graves' disease).
• Goiter: Enlargement of the thyroid gland due to iodine deficiency, impairing hormone synthesis.

A balanced diet with iodine (e.g., iodized salt) is essential for proper thyroid function.

The pancreas plays a crucial role in maintaining blood glucose levels through the secretion of two key hormones: insulin and glucagon. These hormones work antagonistically to ensure glucose homeostasis.

Insulin is secreted by the beta cells of the pancreatic islets when blood glucose levels are high (e.g., after a meal). Its mechanism of action includes:
1. Promoting glucose uptake by cells, especially in the liver, muscles, and adipose tissue.
2. Stimulating glycogenesis (conversion of glucose to glycogen for storage in the liver and muscles).
3. Inhibiting gluconeogenesis (production of glucose from non-carbohydrate sources).

Glucagon is secreted by the alpha cells of the pancreatic islets when blood glucose levels are low (e.g., during fasting). Its mechanism of action includes:
1. Stimulating glycogenolysis (breakdown of glycogen into glucose in the liver).
2. Promoting gluconeogenesis to increase glucose production.

The regulation of blood glucose is vital because:
1. It ensures a constant energy supply to the brain and other organs.
2. Prevents hyperglycemia (high blood sugar), which can damage tissues, or hypoglycemia (low blood sugar), which can cause seizures or unconsciousness.
3. Maintains metabolic balance, supporting overall health and preventing diseases like diabetes mellitus.

The thyroid gland secretes two primary hormones: thyroxine (T4) and triiodothyronine (T3), which play a crucial role in regulating the body's metabolic rate. These hormones influence almost every cell in the body by:

• Enhancing oxygen consumption and heat production (calorigenic effect).
• Promoting growth and development, especially in the nervous system and bones.
• Regulating carbohydrate, protein, and fat metabolism to maintain energy balance.

Hypothyroidism occurs when the thyroid gland is underactive, leading to insufficient hormone production. Symptoms include:

• Weight gain, fatigue, and cold intolerance due to slowed metabolism.
• Goiter (enlarged thyroid) caused by iodine deficiency, as seen in endemic goiter.
• Cretinism in children, characterized by stunted growth and mental retardation.

Hyperthyroidism results from excessive hormone secretion, as in Graves' disease. Symptoms include:

• Weight loss, increased heart rate, and nervousness due to heightened metabolism.
• Exophthalmos (bulging eyes) caused by autoimmune attacks on eye muscles.

Both conditions highlight the importance of thyroid hormones in maintaining homeostasis. Proper diagnosis and treatment (e.g., hormone replacement for hypothyroidism or antithyroid drugs for hyperthyroidism) are essential for health.

The thyroid gland secretes two primary hormones: thyroxine (T4) and triiodothyronine (T3), which play a crucial role in regulating the body's metabolic activities. These hormones influence the basal metabolic rate (BMR), growth, development, and energy production.

Functions of Thyroid Hormones:
1. Metabolism Regulation: T3 and T4 increase the metabolic rate of cells, enhancing oxygen consumption and energy production.
2. Growth and Development: They are essential for normal growth, especially of the nervous system and skeletal muscles.
3. Maintenance of Body Temperature: They help in thermoregulation by stimulating heat production.

Hyposecretion (Hypothyroidism):
- Cretinism: In children, it leads to stunted growth, mental retardation, and delayed puberty.
- Myxedema: In adults, it causes weight gain, fatigue, and cold intolerance.
- Goiter: Enlargement of the thyroid gland due to iodine deficiency.

Hypersecretion (Hyperthyroidism):
- Graves' Disease: An autoimmune disorder causing weight loss, increased heart rate, and bulging eyes (exophthalmos).
- High BMR: Leads to excessive sweating, nervousness, and heat intolerance.

Thus, the thyroid hormones are vital for maintaining homeostasis, and their imbalance can lead to severe disorders.

The thyroid gland secretes two primary hormones: thyroxine (T4) and triiodothyronine (T3), which play a crucial role in regulating the body's metabolic rate. These hormones influence various physiological processes, including:

• Basal Metabolic Rate (BMR): They increase oxygen consumption and energy production in cells, ensuring optimal metabolic activity.
• Growth and Development: Essential for normal growth, especially of the nervous system and bones in children.
• Carbohydrate, Protein, and Fat Metabolism: They enhance the breakdown of nutrients to release energy.
• Maintenance of Body Temperature: By stimulating heat production in tissues.

Hypothyroidism occurs due to insufficient thyroid hormone secretion, leading to symptoms like weight gain, fatigue, cold intolerance, and slowed mental functions (e.g., cretinism in children).

Hyperthyroidism results from excessive hormone secretion, causing weight loss, increased heart rate, nervousness, and heat intolerance (e.g., Graves' disease).

Both conditions highlight the importance of thyroid hormones in maintaining homeostasis. Regular iodine intake is vital for thyroid function, as iodine is a key component of T3 and T4.

The thyroid gland secretes two primary hormones: thyroxine (T4) and triiodothyronine (T3), which play a crucial role in regulating the body's metabolic rate. These hormones influence almost every cell in the body by increasing basal metabolic rate (BMR), enhancing protein synthesis, and promoting growth and development, especially in the nervous system.

Functions of Thyroid Hormones:

• Regulate carbohydrate, protein, and fat metabolism to maintain energy balance.
• Stimulate oxygen consumption by tissues, increasing heat production.
• Essential for normal brain development and bone growth in children.
• Maintain cardiac output and digestive functions.

Hyposecretion (Hypothyroidism): A deficiency of thyroid hormones leads to conditions like cretinism in children (stunted growth, mental retardation) and myxedema in adults (weight gain, lethargy, cold intolerance). It can also cause goiter due to lack of iodine, which is essential for hormone synthesis.

Hypersecretion (Hyperthyroidism): Excess secretion results in Graves' disease, characterized by weight loss, increased heart rate, sweating, and protruding eyeballs (exophthalmos). The metabolic rate becomes excessively high, leading to nervousness and muscle weakness.

Thus, thyroid hormones are vital for maintaining homeostasis, and their imbalance can severely disrupt bodily functions.

The thyroid hormones, primarily thyroxine (T4) and triiodothyronine (T3), play a crucial role in regulating metabolism, growth, and development in the human body. These hormones are secreted by the thyroid gland and influence almost every cell.

Functions of Thyroid Hormones:
1. Metabolic Regulation: They increase the basal metabolic rate (BMR) by stimulating oxygen consumption and energy production.
2. Growth and Development: Essential for normal physical and mental development, especially in children.
3. Cardiovascular Effects: Enhance heart rate and cardiac output.
4. Digestive System: Stimulate gut motility and digestive enzyme secretion.
5. Central Nervous System: Crucial for brain development and function.

Hypo-secretion (Hypothyroidism):
Deficiency of thyroid hormones can lead to:
- Goiter: Enlargement of the thyroid gland due to iodine deficiency.
- Cretinism: Stunted growth and mental retardation in children.
- Myxedema: Swelling of skin, lethargy, and weight gain in adults.

Hyper-secretion (Hyperthyroidism):
Excess thyroid hormones cause:
- Graves' Disease: Autoimmune disorder leading to bulging eyes, weight loss, and rapid heartbeat.
- Exophthalmos: Protrusion of eyeballs due to swelling behind the eyes.
- Increased BMR: Leads to excessive sweating, nervousness, and heat intolerance.

Example: Iodine deficiency in diet can cause hypothyroidism, leading to goiter, while an overactive thyroid gland can result in hyperthyroidism, as seen in Graves' disease.

The adrenal gland, located above each kidney, consists of two parts: the adrenal cortex and the adrenal medulla. Each part secretes different hormones that play crucial roles in maintaining homeostasis, especially during stress.

Adrenal Cortex Hormones:
1. Glucocorticoids (e.g., cortisol): These regulate metabolism by increasing blood glucose levels through gluconeogenesis. They also suppress the immune response and reduce inflammation.
2. Mineralocorticoids (e.g., aldosterone): These maintain electrolyte balance by promoting sodium reabsorption and potassium excretion in the kidneys.
3. Androgens: These are sex hormones that contribute to secondary sexual characteristics, though in smaller quantities compared to gonads.

Adrenal Medulla Hormones:
1. Adrenaline (epinephrine) and noradrenaline (norepinephrine): These are released during the fight-or-flight response. They increase heart rate, dilate airways, and redirect blood flow to muscles and the brain, preparing the body to handle stress.

Role in Homeostasis During Stress:
During stress, the hypothalamus activates the adrenal glands via the sympathetic nervous system and the HPA axis (Hypothalamus-Pituitary-Adrenal axis).

• Short-term stress: Adrenaline and noradrenaline provide immediate energy by breaking down glycogen and fats.
• Long-term stress: Cortisol ensures sustained energy by promoting protein and fat metabolism while suppressing non-essential functions like digestion and reproduction.

The thyroid hormones, primarily thyroxine (T4) and triiodothyronine (T3), play a crucial role in regulating metabolism, growth, and development. These hormones influence:

• Basal Metabolic Rate (BMR): They increase oxygen consumption and energy production in cells.
• Growth and Development: Essential for normal skeletal and nervous system development, especially in children.
• Cardiovascular System: Enhance heart rate and cardiac output.
• Protein Synthesis: Promote anabolic processes in cells.

Hypothyroidism occurs due to insufficient thyroid hormone production. Symptoms include:

• Weight gain, fatigue, and cold intolerance due to slowed metabolism.
• Myxedema in adults, characterized by swelling of skin and tissues.
• Cretinism in children, leading to stunted growth and mental retardation.

Hyperthyroidism results from excessive thyroid hormone secretion. Symptoms include:

• Weight loss, tremors, and heat intolerance due to increased metabolism.
• Graves' disease, an autoimmune disorder causing bulging eyes (exophthalmos).

For example, iodine deficiency can cause hypothyroidism, while overactive thyroid nodules may lead to hyperthyroidism.

Insulin and glucagon are pancreatic hormones that regulate blood glucose levels through antagonistic actions:

Insulin:

• Secreted by beta cells of the pancreas in response to high blood glucose.
• Promotes glycogenesis (glucose to glycogen) in liver and muscle cells.
• Enhances glucose uptake by cells, reducing blood sugar levels.
• Inhibits gluconeogenesis (glucose synthesis from non-carbohydrates).

Glucagon:

• Secreted by alpha cells of the pancreas during low blood glucose.
• Stimulates glycogenolysis (glycogen breakdown) in the liver.
• Activates gluconeogenesis to produce glucose from amino acids and fats.

In diabetes mellitus, this balance is disrupted:

• Type 1 Diabetes: Autoimmune destruction of beta cells leads to insulin deficiency, causing hyperglycemia.
• Type 2 Diabetes: Cells become insulin resistant, impairing glucose uptake despite normal/high insulin levels.

Uncontrolled diabetes results in symptoms like polyuria (excessive urination), polydipsia (increased thirst), and weight loss due to alternative energy sources like fats and proteins.