Search for hyperglycemia

CNS Stimulants ADHD Medications Amphetamine (Adderall, Dexedrine) Mechanism of Action: Stimulates excitatory neurons, increases dopamine & norepinephrine. Indications: ADHD, narcolepsy. Adverse Effects: Increased HR/BP, anxiety, tremor, insomnia, headache, decreased appetite, GI distress, dry mouth. Contraindications: Cardiac abnormalities, hypertension, anxiety, agitation, glaucoma, MAOI use (within 14 days). Nursing Implications: Administer 4-6 hours before bedtime. Take on an empty stomach. Monitor BP, pulse, weight, growth patterns in children. Avoid abrupt withdrawal. Methylphenidate (Ritalin, Concerta) Mechanism of Action: CNS stimulant affecting dopamine reuptake. Indications: ADHD, narcolepsy. Adverse Effects: Same as amphetamines. Nursing Implications: Same as amphetamines. Lisdexamfetamine (Vyvanse) Mechanism of Action: Converted into dextroamphetamine. Indications: ADHD, binge-eating disorder. Nursing Implications: Similar to amphetamines. Atomoxetine (Strattera) Mechanism of Action: Selective norepinephrine reuptake inhibitor. Indications: ADHD (children >6 and adults). Adverse Effects: Lower abuse potential, less insomnia, but Black Box Warning for suicidal thoughts. Nursing Implications: Monitor mental health for suicidal ideation. Narcolepsy Medications Modafinil (Provigil) Mechanism of Action: Low abuse potential stimulant. Indications: Narcolepsy, shift work sleep disorder. Nursing Implications: Monitor BP & mental health. Antimigraine Medications Rizatriptan (Maxalt), Sumatriptan (Imitrex) Mechanism of Action: Serotonin receptor agonist, causing vasoconstriction. Indications: Acute migraine treatment. Adverse Effects: Tingling, flushing, chest tightness, rebound headaches if overused. Contraindications: Cardiovascular disease, hypertension, glaucoma. Nursing Implications: Administer at first sign of migraine. Avoid triggers. Monitor cardiac history. Endocrine Medications Pituitary Medications Somatropin (Humotrope) Mechanism of Action: Growth hormone replacement. Indications: Growth failure (hypopituitarism, HIV wasting). Adverse Effects: Hyperglycemia, hypothyroidism, injection site reactions. Nursing Implications: Monitor growth, motor skills, thyroid, and glucose levels. Rotate injection sites. Octreotide (Sandostatin) Mechanism of Action: GH antagonist. Indications: Acromegaly, GH-producing tumors. Adverse Effects: GI distress, glucose changes, cardiac conduction issues. Nursing Implications: Monitor glucose, EKG, growth. ADH Medications Vasopressin (Pitressin) & Desmopressin (DDAVP) Mechanism of Action: Mimics ADH. Indications: Vasopressin: Hypotension, hemorrhage. Desmopressin: Diabetes insipidus, bedwetting. Adverse Effects: Increased BP, headache, GI distress. Nursing Implications: Monitor VS, urine output, cardiac status. Thyroid Medications Levothyroxine (Synthroid) Mechanism of Action: Synthetic T4. Indications: Hypothyroidism. Adverse Effects: Hyperthyroid symptoms. Nursing Implications: Administer before breakfast on an empty stomach. Monitor thyroid labs (TSH, T3, T4). Avoid iodine-rich foods, iron/calcium supplements. Propylthiouracil (PTU) Mechanism of Action: Inhibits thyroid hormone production. Indications: Hyperthyroidism, thyroid storm. Adverse Effects: GI distress, bone marrow suppression. Nursing Implications: Monitor thyroid levels & CBC. Avoid iodine-rich foods. Radioactive Iodine (I-131) Mechanism of Action: Destroys thyroid tissue. Indications: Hyperthyroidism, thyroid cancer. Adverse Effects: Radiation sickness, Pregnancy Category X. Nursing Implications: Radiation precautions: Avoid close contact, use separate utensils, increase fluids. Adrenal Medications Glucocorticoids Hydrocortisone (Solu-Cortef), Prednisone (Deltasone), Dexamethasone (Decadron), Methylprednisolone (Solu-Medrol) Mechanism of Action: Anti-inflammatory, immunosuppressant. Indications: Adrenal insufficiency, inflammatory/autoimmune diseases. Adverse Effects: Metabolic: Hyperglycemia, weight gain, Cushing’s syndrome. Musculoskeletal: Osteoporosis, muscle wasting. CV: Hypertension, edema. Neuro: Mood swings, insomnia. Nursing Implications: Administer in the morning with food. Taper off slowly to prevent adrenal crisis. Monitor glucose levels with long-term use. Avoid sick contacts due to immune suppression. Mineralocorticoids Fludrocortisone (Florinef) Mechanism of Action: Mimics aldosterone (Na & water retention). Indications: Addison’s disease, adrenal insufficiency. Adverse Effects: Hypertension, hypokalemia, edema. Nursing Implications: Monitor BP, electrolytes (Na, K). Immunosuppressants Cyclosporine (Sandimmune), Tacrolimus (Prograf) Mechanism of Action: Suppresses immune response. Indications: Organ transplant, autoimmune diseases. Adverse Effects: Increased risk for infections, nephrotoxicity, diabetes. Nursing Implications: Strict dosing schedule (same time every day). Avoid grapefruit juice & styrofoam cups. No live vaccines (MMR, Varicella, Smallpox). Report any signs of infection immediately. Lifespan Considerations Pediatrics: Monitor growth in children using ADHD meds & growth hormones. Pregnancy: Avoid radioactive iodine (I-131) & immunosuppressants. Elderly: Caution with stimulants & corticosteroids (risk of cardiac issues, osteoporosis). Patient Teaching CNS Stimulants: Avoid abrupt withdrawal. Monitor growth (children). Thyroid Meds: Take levothyroxine on an empty stomach. Avoid iodine-rich foods if on PTU. Corticosteroids: Taper off gradually. Monitor glucose, avoid infections. Immunosuppressants: No live vaccines. Strict dosing schedule. Insulins Rapid-acting Insulins (Insulin lispro - Humalog, Insulin aspart - Novolog) Mechanism of Action: Fast-acting insulin that mimics natural insulin secretion in response to meals. Indications: Type 1 or Type 2 Diabetes. Adverse Effects: Hypoglycemia, weight gain, lipodystrophy at injection sites. Nursing Implications: Must eat a meal after injection. Administer subcutaneously (SQ) or via infusion pump. Clear, colorless solution. Short-acting Insulin (Regular insulin - Humulin R) Mechanism of Action: Provides short-term glucose control. Indications: Type 1 & Type 2 Diabetes. Adverse Effects: Hypoglycemia, weight gain. Nursing Implications: Onset: 30-60 min, Peak: 2.5 hr, Duration: 6-10 hr. Can be administered IV, IM, or SQ. Clear, colorless solution. Intermediate-acting Insulin (NPH - Isophane insulin suspension) Mechanism of Action: Delayed onset but prolonged glucose control. Indications: Often combined with regular insulin for Type 1 & Type 2 Diabetes. Adverse Effects: Hypoglycemia, weight gain. Nursing Implications: Onset: 1-2 hr, Peak: 4-8 hr, Duration: 10-18 hr. Cloudy suspension, administered SQ. Usually given twice daily before meals. Long-acting Insulins (Insulin glargine - Lantus, Insulin detemir - Levemir) Mechanism of Action: Provides basal insulin coverage with no peak effect. Indications: Type 1 & Type 2 Diabetes. Adverse Effects: Hypoglycemia (less risk), weight gain. Nursing Implications: Onset: 1-2 hr, No peak, Duration: 24 hr. DO NOT mix with other insulins. Clear, colorless solution. Oral Antidiabetics Biguanides (Metformin - Glucophage) Mechanism of Action: Decreases hepatic glucose production & increases insulin sensitivity. Indications: First-line treatment for Type 2 Diabetes. Adverse Effects: GI discomfort, diarrhea, metallic taste, reduced B12 levels. Black Box Warning: Risk of lactic acidosis (especially in renal failure). Nursing Implications: Administer 30 min before meals. Hold if contrast dye is used (renal failure risk). Sulfonylureas (Glipizide - Glucotrol) Mechanism of Action: Stimulates pancreatic insulin release. Indications: Type 2 Diabetes (early stages). Adverse Effects: Hypoglycemia, weight gain, nausea. Contraindications: Sulfa allergy. Nursing Implications: Give 30 min before meals. Monitor for hypoglycemia. Glinides (Repaglinide - Prandin) Mechanism of Action: Increases insulin secretion from beta cells. Indications: Type 2 Diabetes (postprandial glucose control). Adverse Effects: Hypoglycemia, weight gain. Black Box Warning: May exacerbate heart failure. Nursing Implications: Take with each meal, skip if meal is skipped. Glitazones (Pioglitazone - Actos) Mechanism of Action: Improves insulin sensitivity. Indications: Type 2 Diabetes (often combined with metformin or sulfonylureas). Adverse Effects: Fluid retention, weight gain, fractures. Black Box Warning: May exacerbate heart failure. Nursing Implications: Weigh daily. Monitor for heart failure signs. Alpha-glucosidase Inhibitors (Acarbose - Precose) Mechanism of Action: Delays carbohydrate absorption. Indications: Type 2 Diabetes (postprandial glucose control). Adverse Effects: GI issues (flatulence, diarrhea). Contraindications: GI disorders (IBD, malabsorption). Nursing Implications: Take with first bite of meal. DPP-4 Inhibitors (Gliptins) (Sitagliptin - Januvia) Mechanism of Action: Enhances incretin hormone function. Indications: Adjunct to diet/exercise in Type 2 Diabetes. Adverse Effects: URI, headache, diarrhea. Nursing Implications: Take once daily, with or without food. SGLT-2 Inhibitors (Canagliflozin - Invokana) Mechanism of Action: Inhibits glucose reabsorption in kidneys. Indications: Type 2 Diabetes (weight loss benefit). Adverse Effects: UTIs, yeast infections, dehydration, ketoacidosis. Nursing Implications: Take once daily before breakfast. Injectable Non-Insulin Medications Amylin Agonists (Pramlintide - Symlin) Mechanism of Action: Slows gastric emptying, suppresses glucagon. Indications: Type 1 & Type 2 Diabetes. Adverse Effects: Nausea, vomiting, anorexia. Contraindications: Gastroparesis. Nursing Implications: Inject before meals. Take at least 1 hr before oral meds. Incretin Mimetics (Exenatide - Byetta) Mechanism of Action: Enhances insulin secretion. Indications: Type 2 Diabetes (used when oral meds fail). Adverse Effects: GI symptoms, weight loss, thyroid tumors (Black Box Warning). Nursing Implications: Administer SQ 1 hr before meals. Glucose-Elevating Agents Glucagon Indications: Severe hypoglycemia. Adverse Effects: Vomiting (turn patient on side). Nursing Implications: Used when patient cannot take oral glucose. Dextrose 50% in Water (D50W) Indications: Emergency treatment of hypoglycemia. Nursing Implications: Administer IV. Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) Salicylates (Aspirin - ASA) Mechanism of Action: COX-1 & COX-2 inhibitor, antiplatelet. Indications: Pain, fever, inflammation, CV prevention. Adverse Effects: GI bleeding, Reye’s syndrome in children. Nursing Implications: Do not give to children with viral infections. Acetic Acid Derivative (Ketorolac - Toradol) Indications: Short-term pain management (up to 5 days). Adverse Effects: Renal impairment, GI distress. COX-2 Inhibitor (Celecoxib - Celebrex) Indications: Osteoarthritis, rheumatoid arthritis. Adverse Effects: CV risk (Black Box Warning). Contraindications: Sulfa allergy. Propionic Acid Derivatives (Ibuprofen, Naproxen) Indications: Pain, inflammation, fever. Adverse Effects: GI distress, bleeding risk. Antigout Medications Allopurinol (Zyloprim) Mechanism of Action: Reduces uric acid production. Indications: Chronic gout prevention. Adverse Effects: Stevens-Johnson syndrome. Nursing Implications: Take with food. Colchicine (Colcrys) Mechanism of Action: Reduces inflammatory response. Indications: Acute gout attack. Adverse Effects: GI distress, bleeding risk. Nursing Implications: Hydration (3L/day). Immunizations Active Immunizing Drugs Mechanism of Action: Stimulate the immune system to produce antibodies against specific pathogens, offering long-term immunity. Indications: Prevention of infectious diseases. Adverse Effects: Common: Soreness, fever, mild rash. Severe: Fever >103°F, encephalitis, convulsions, anaphylaxis. Contraindications: Immunocompromised patients, pregnancy (some vaccines), active infections. Nursing Implications: Assess medical history, immune status, and pregnancy. Administer vaccines at appropriate sites: Infants: Mid-lateral thigh. Older children/adults: Deltoid muscle. Use warm compresses, Tylenol for mild reactions. Report severe reactions to VAERS (Vaccine Adverse Event Reporting System). Examples of Active Immunizations: Diphtheria, tetanus toxoids, acellular pertussis (DTaP, Td): Prevents diphtheria, tetanus, and pertussis. Haemophilus influenzae type B (Hib): Prevents bacterial infections, especially in children. Hepatitis B vaccine: Prevents Hep B infection. Influenza vaccine: Annual vaccine for flu prevention. Measles, mumps, rubella (MMR): Prevents viral infections. Pneumococcal vaccine: Protects against pneumococcal infections (pneumonia, meningitis). Poliovirus vaccine (IPV): Prevents poliomyelitis. Rabies vaccine: Given for rabies exposure or pre-exposure prophylaxis. Human papillomavirus (HPV - Gardasil): Prevents HPV-related cancers. Herpes zoster (Zostavax, Shingrix): Protects against shingles. Varicella vaccine: Prevents chickenpox. Passive Immunizing Drugs Mechanism of Action: Provides preformed antibodies for immediate protection; temporary immunity. Indications: Post-exposure prophylaxis in high-risk patients. Examples: Hepatitis B immunoglobulin: Post-exposure protection for Hepatitis B. Immunoglobulin: General immune support. Rabies immunoglobulin: Post-exposure prophylaxis after animal bites. Tetanus immunoglobulin: Used in unvaccinated individuals exposed to tetanus. Dermatologic Medications Antibacterials Bacitracin Mechanism of Action: Inhibits bacterial cell wall synthesis. Indications: Minor skin infections. Adverse Effects: Burning, itching. Neomycin & Polymyxin B (Neosporin) Mechanism of Action: Broad-spectrum antibacterial. Indications: Minor wounds. Adverse Effects: Local irritation. Mupirocin (Bactroban) Indications: Topical: Treats impetigo (Staphylococcus, Streptococcus infections). Intranasal: Used for MRSA colonization. Adverse Effects: Burning, itching. Silver Sulfadiazine (Silvadene) Mechanism of Action: Acts on bacterial cell wall. Indications: Burn treatment (prevention of infection). Adverse Effects: Pain, burning, contraindicated in sulfa allergy. Antiacne Medications Benzoyl Peroxide Mechanism of Action: Releases oxygen, killing acne bacteria. Indications: Mild to moderate acne. Adverse Effects: Red, peeling skin, warmth. Tretinoin (Retin-A) Mechanism of Action: Vitamin A derivative, stimulates cell turnover. Indications: Acne, UV damage. Adverse Effects: Skin peeling, severe sunburn risk (use sunscreen). Isotretinoin (Accutane) Mechanism of Action: Sebaceous gland suppression. Indications: Severe cystic acne. Adverse Effects: Teratogenic (Pregnancy Category X), liver toxicity, mood changes. Black Box Warning: IPLEDGE Program (2 contraceptive methods required). Antifungals Clotrimazole (Lotrimin) Mechanism of Action: Inhibits fungal growth. Indications: Athlete’s foot, ringworm, yeast infections. Adverse Effects: Local irritation. Miconazole (Monistat) Mechanism of Action: Antifungal, some Gram-positive action. Indications: Yeast infections, jock itch, athlete’s foot. Adverse Effects: Burning, itching, pelvic cramps. Antivirals Acyclovir (Zovirax) Mechanism of Action: Inhibits viral DNA replication. Indications: Herpes simplex (HSV-1 & HSV-2), shingles. Adverse Effects: Stinging, rash. Miscellaneous Dermatologics Permethrin (Elimite) Mechanism of Action: Neurotoxic to lice/scabies. Indications: Head lice, scabies. Adverse Effects: Itching, burning. Ophthalmic Medications Cholinergic Drugs (Miotics) Acetylcholine (Miochol-E) Indications: Induces miosis (pupil constriction) during surgery. Adverse Effects: Eye discomfort, blurred vision. Pilocarpine (Pilocar) Mechanism of Action: Stimulates cholinergic receptors, reduces intraocular pressure. Indications: Glaucoma, ocular surgery. Adverse Effects: Blurred vision, tearing, reduced night vision. Beta-Adrenergic Blockers Timolol (Timoptic) Mechanism of Action: Reduces aqueous humor production & increases outflow. Indications: Glaucoma, ocular hypertension. Adverse Effects: Eye irritation, systemic effects possible (bradycardia, hypotension). Otic Medications Ofloxacin (Floxin Otic) Mechanism of Action: Fluoroquinolone antibiotic (bacterial DNA disruption). Indications: Otitis externa & media. Adverse Effects: Mild itching/pain. Carbamide Peroxide (Debrox) Mechanism of Action: Softens & breaks down earwax. Indications: Earwax removal. Adverse Effects: Ear irritation. Nursing Considerations Lifespan Considerations Pediatrics: Infants: Thigh for vaccines, avoid aspirin (Reye’s syndrome risk). Monitor growth with long-term corticosteroids. Pregnancy: Avoid live vaccines (MMR, varicella, HPV, Zoster). Avoid isotretinoin (teratogenic). Elderly: Caution with ophthalmic beta-blockers (can cause systemic effects). Monitor renal function with fluoroquinolones (ototoxicity risk). Patient Teaching Vaccines: Keep records, report reactions. Use Tylenol, not aspirin for fever. Dermatologics: Apply with gloves, wash hands before & after. Sunscreen required with tretinoin & isotretinoin. Ophthalmic/Otic: Apply pressure to inner canthus after eye drops (reduce systemic absorption). Hold ear up & back (adults), down & back (children) for otic drops

Updated 54d ago

INTRODUCTION Medulla is the inner part of adrenal gland and it forms 20% of the mass of adrenal gland. It is made up of interlacing cords of cells known as chromaffin cells. Chromaffin cells are also called pheochrome cells or chromophil cells. These cells contain fine granules which are stained brown by potassium dichromate. Types of chromaffin cells Adrenal medulla is formed by two types of chromaffin cells: 1. Adrenaline-secreting cells (90%) 2. Noradrenaline-secreting cells (10%). HORMONES OF ADRENAL MEDULLA Adrenal medullary hormones are the amines derived from catechol and so these hormones are called catecholamines. Catecholamines secreted by adrenal medulla 1. Adrenaline or epinephrine 2. Noradrenaline or norepinephrine 3. Dopamine. PLASMA LEVEL OF CATECHOLAMINES 1. Adrenaline : 3 μg/dL 2. Noradrenaline : 30 μg/dL 3. Dopamine : 3.5 μg/dL HALF-LIFE OF CATECHOLAMINES Half-life of catecholamines is about 2 minutes. SYNTHESIS OF CATECHOLAMINES Catecholamines are synthesized from the amino acid tyrosine in the chromaffin cells of adrenal medulla (Fig. 71.1). These hormones are formed from phenylalanine also. But phenylalanine has to be converted into tyrosine. Stages of Synthesis of Catecholamines 1. Formation of tyrosine from phenylalanine in the presence of enzyme phenylalanine hydroxylase 2. Uptake of tyrosine from blood into the chromaffin cells of adrenal medulla by active transport 3. Conversion of tyrosine into dihydroxyphenylalanine (DOPA) by hydroxylation in the presence of tyrosine hydroxylase 440 Section 6tEndocrinology FIGURE 71.1: Synthesis of catecholamines. DOPA = Di- hydroxyphenylalanine, PNMT = Phenylethanolamine-N- methyltransferase. 4. Decarboxylation of DOPA into dopamine by DOPA decarboxylase 5. Entry of dopamine into granules of chromaffin cells 6. Hydroxylation of dopamine into noradrenaline by the enzyme dopamine beta-hydroxylase 7. Release of noradrenaline from granules into the cytoplasm 8. Methylation of noradrenaline into adrenaline by the most important enzyme called phenylethanolamine- N-methyltransferase (PNMT). PNMT is present in chromaffin cells. METABOLISM OF CATECHOLAMINES Eighty five percent of noradrenaline is taken up by the sympathetic adrenergic neurons. Remaining 15% of noradrenaline and adrenaline are degraded (Fig. 71.2). FIGURE 71.2: Metabolism of catecholamines. COMT = Catechol-O-methyltransferase, MAO = Monoamine oxidase. Stages of Metabolism of Catecholamines 1. Methoxylation of adrenaline into meta-adrenaline and noradrenaline into metanoradrenaline in the presence of ‘catechol-O-methyltransferase’ (COMT). Meta-adrenaline and meta-noradrenaline are together called metanephrines 2. Oxidation of metanephrines into vanillylmandelic acid (VMA) by monoamine oxidase (MAO) Removal of Catecholamines Catecholamines are removed from body through urine in three forms: i. 15% as free adrenaline and free noradrenaline ii. 50% as free or conjugated meta-adrenaline and meta-noradrenaline iii. 35% as vanillylmandelic acid (VMA). ACTIONS OF ADRENALINE AND NORADRENALINE Adrenaline and noradrenaline stimulate the nervous system. Adrenaline has significant effects on metabolic functions and both adrenaline and noradrenaline have significant effects on cardiovascular system. MODE OF ACTION OF ADRENALINE AND NORADRENALINE – ADRENERGIC RECEPTORS Actions of adrenaline and noradrenaline are executed by binding with receptors called adrenergic receptors, which are present in the target organs. Chapter 71tAdrenal Medulla 441 Adrenergic receptors are of two types: 1. Alpha-adrenergic receptors, which are subdivided into alpha-1 and alpha-2 receptors 2. Beta-adrenergic receptors, which are subdivided into beta-1 and beta-2 receptors. Refer Table 71.1 for the mode of action of these receptors. ACTIONS Circulating adrenaline and noradrenaline have similar effect of sympathetic stimulation. But, the effect of adrenal hormones is prolonged 10 times more than that of sympathetic stimulation. It is because of the slow inactivation, slow degradation and slow removal of these hormones. Effects of adrenaline and noradrenaline on various target organs depend upon the type of receptors present in the cells of the organs. Adrenaline acts through both alpha and beta receptors equally. Noradrenaline acts mainly through alpha receptors and occasionally through beta receptors. 1. On Metabolism (via Alpha and Beta Receptors) Adrenaline influences the metabolic functions more than noradrenaline. i. General metabolism: Adrenaline increases oxygen consumption and carbon dioxide removal. It increases basal metabolic rate. So, it is said to be a calorigenic hormone ii. Carbohydrate metabolism: Adrenaline increases the blood glucose level by increasing the glycogenolysis in liver and muscle. So, a large quantity of glucose enters the circulation iii. Fat metabolism: Adrenaline causes mobilization of free fatty acids from adipose tissues. Catecholamines need the presence of glucocorticoids for this action. 2. On Blood (via Beta Receptors) Adrenaline decreases blood coagulation time. It increases RBC count in blood by contracting smooth muscles of splenic capsule and releasing RBCs from spleen into circulation. 3. On Heart (via Beta Receptors) Adrenaline has stronger effects on heart than nor- adrenaline. It increases overall activity of the heart, i.e. i. Heart rate (chronotropic effect) ii. Force of contraction (inotropic effect) iii. Excitability of heart muscle (bathmotropic effect) iv. Conductivity in heart muscle (dromotropic effect). 4. On Blood Vessels (via Alpha and Beta-2 Receptors) Noradrenaline has strong effects on blood vessels. It causes constriction of blood vessels throughout the body via alpha receptors. So it is called ‘general vasoconstrictor’. Vasoconstrictor effect of noradrena- line increases total peripheral resistance. Adrenaline also causes constriction of blood vessels. However, it causes dilatation of blood vessels in skeletal muscle, liver and heart through beta-2 receptors. So, the total peripheral resistance is decreased by adrenaline. Catecholamines need the presence of glucocor- ticoids, for these vascular effects. 5. On Blood Pressure (via Alpha and Beta Receptors) Adrenaline increases systolic blood pressure by increasing the force of contraction of the heart and cardiac output. But, it decreases diastolic blood pressure by reducing the total peripheral resistance. Noradrenaline increases diastolic pressure due to general vasoconstrictor effect by increasing the total peripheral resistance. It also increases the systolic blood pressure to a slight extent by its actions on heart. The action of catecholamines on blood pressure needs the presence of glucocorticoids. TABLE 71.1: Adrenergic receptors Receptor Mode of action Response Alpha-1 receptor Activates IP3 through phospholipase C Mediates more of noradrenaline actions than adrenaline actions Alpha-2 receptor Inhibits adenyl cyclase and cAMP Beta-1 receptor Activates adenyl cyclase and cAMP Mediates actions of adrenaline and noradrenaline equally Beta-2 receptor Activates adenyl cyclase and cAMP Mediates more of adrenaline actions than noradrenaline actions IP3 = Inositol triphosphate 442 Section 6tEndocrinology Thus, hypersecretion of catecholamines leads to hypertension. 6. On Respiration (via Beta-2 Receptors) Adrenaline increases rate and force of respiration. Adrenaline injection produces apnea, which is known as adrenaline apnea. It also causes bronchodilation. 7. On Skin (via Alpha and Beta-2 Receptors) Adrenaline causes contraction of arrector pili. It also increases the secretion of sweat. 8. On Skeletal Muscle (via Alpha and Beta-2 Receptors) Adrenaline causes severe contraction and quick fatigue of skeletal muscle. It increases glycogenolysis and release of glucose from muscle into blood. It also causes vasodilatation in skeletal muscles. 9. On Smooth Muscle (via Alpha and Beta Receptors) Catecholamines cause contraction of smooth muscles in the following organs: i. Splenic capsule ii. Sphincters of gastrointestinal (GI) tract iii. Arrector pili of skin iv. Gallbladder v. Uterus vi. Dilator pupillae of iris vii. Nictitating membrane of cat. Catecholamines cause relaxation of smooth muscles in the following organs: i. Non-sphincteric part of GI tract (esophagus, stomach and intestine) ii. Bronchioles iii. Urinary bladder. 10. On Central Nervous System (via Beta Receptors) Adrenaline increases the activity of brain. Adrenaline secretion increases during ‘fight or flight reactions’ after exposure to stress. It enhances the cortical arousal and other facilitatory functions of central nervous system. 11. Other Effects of Catecholamines i. On salivary glands (via alpha and beta-2 receptors): Cause vasoconstriction in salivary gland, leading to mild increase in salivary secretion ii. On sweat glands (via beta-2 receptors): Increase the secretion of apocrine sweat glands iii. On lacrimal glands (via alpha receptors): Increase the secretion of tears iv. On ACTH secretion (via alpha receptors): Adrenaline increases ACTH secretion v. On nerve fibers (via alpha receptors): Adrenaline decreases the latency of action potential in the nerve fibers, i.e. electrical activity is accelerated vi. On renin secretion (via beta receptors): Increase the rennin secretion from juxtaglomerular apparatus of the kidney. REGULATION OF SECRETION OF ADRENALINE AND NORADRENALINE Adrenaline and noradrenaline are secreted from adrenal medulla in small quantities even during rest. During stress conditions, due to sympathoadrenal discharge, a large quantity of catecholamines is secreted. These hormones prepare the body for fight or flight reactions. Catecholamine secretion increases during exposure to cold and hypoglycemia also. DOPAMINE Dopamine is secreted by adrenal medulla. Type of cells secreting this hormone is not known. Dopamine is also secreted by dopaminergic neurons in some areas of brain, particularly basal ganglia. In brain, this hormone acts as a neurotransmitter. Injected dopamine produces the following effects: 1. Vasoconstriction by releasing norepinephrine 2. Vasodilatation in mesentery 3. Increase in heart rate via beta receptors 4. Increase in systolic blood pressure. Dopamine does not affect diastolic blood pressure. Deficiency of dopamine in basal ganglia produces nervous disorder called parkinsonism (Chapter 151). APPLIED PHYSIOLOGY – PHEOCHROMOCYTOMA Pheochromocytoma is a condition characterized by hypersecretion of catecholamines. Cause Pheochromocytoma is caused by tumor of chromophil cells in adrenal medulla. It is also caused rarely by tumor of sympathetic ganglia (extra-adrenal pheochromocytoma). Chapter 71tAdrenal Medulla 443 Signs and Symptoms Characteristic feature of pheochromocytoma is hyper- tension. This type of hypertension is known as endocrine or secondary hypertension. Other features: 1. Anxiety 2. Chest pain 3. Fever 4. Headache 5. Hyperglycemia 6. Metabolic disorders 7. Nausea and vomiting 8. Palpitation 9. Polyuria and glucosuria 10. Sweating and flushing 11. Tachycardia 12. Weight loss. Tests for Pheochromocytoma Pheochromocytoma is detected by measuring meta- nephrines and vanillylmandelic acid in urine and Cathecolamines in olasma

Updated 79d ago

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