Chemical Coordination and Integration

Beginner - Story ModeTopper - Revision

1. Endocrine vs Exocrine - Post Office vs Courier

Exocrine glands have ducts like courier with address pipe directly to target salivary gland to mouth. Endocrine glands ductless like post office throws letters hormones into blood bloodstream delivers everywhere, target has receptor letterbox.

Story - The Secret Letters: Hormones are secret letters written in chemical ink. Types: Steroid hormones lipid soluble cholesterol derived like cortisol testosterone estrogen progesterone can cross cell membrane directly like VIP entering without check. Protein peptide hormones water soluble insulin glucagon cannot cross membrane needs receptor on surface like visitor needs appointment. Amine hormones tyrosine derived epinephrine norepinephrine thyroxine T3 T4. Characteristics: minute quantity microgram, distant action, slow long-lasting vs nerve fast short, feedback regulated. Endocrine glands: Hypothalamus pituitary pineal thyroid parathyroid thymus adrenal pancreas gonads. Exocrine: salivary sweat mammary.

Part 1A - Endocrine vs Exocrine Post Office vs Courier

Part 1B - Hypothalamus Pituitary Master Gland Zoom

Revision: Exocrine duct present to local target salivary, Endocrine ductless blood to distant target. Hormones: Steroid lipid soluble cholesterol derived cortisol testosterone estrogen progesterone cross membrane, Protein peptide water soluble insulin glucagon surface receptor, Amine tyrosine derived epinephrine thyroxine. Characteristics minute quantity distant slow long-lasting feedback.

2. The Master and Small Kings - Pituitary, Pineal, Thyroid

Hypothalamus is real master controls pituitary. Pituitary is called master gland but actually hypothalamus is super master. Pituitary has adenohypophysis anterior glandular 75% and neurohypophysis posterior neural 25%.

Creative - Company Hierarchy: Hypothalamus CEO gives orders via releasing hormones to pituitary manager. Anterior pituitary pars distalis workers: GH growth hormone bone muscle growth, Prolactin PRL milk production, TSH thyroid stimulating, ACTH adrenal cortex, LH ovulation testosterone, FSH follicle spermatogenesis. Posterior pituitary stores and releases oxytocin uterus contraction milk ejection love hormone and ADH vasopressin water reabsorption made in hypothalamus transported via axons. Pineal gland small king in brain secretes melatonin sleep-wake circadian rhythm jet lag. Thyroid gland butterfly in neck T3 T4 thyroxine contains iodine BMR basal metabolic rate growth, calcitonin lowers blood calcium opposes PTH. Parathyroid 4 small glands behind thyroid PTH parathormone raises calcium bone resorption gut kidney absorption. Calcium regulation seesaw: High Ca2+ calcitonin low, Low Ca2+ PTH high. Tetany low Ca2+ muscle spasm.

Part 2A - Pineal Melatonin Thyroid T3 T4 Parathyroid PTH

Part 2B - Thymus T-cells Adrenal Cortex Medulla Zoom

Revision: Hypothalamus super master releasing hormones → Pituitary master. Anterior adenohypophysis GH PRL TSH ACTH LH FSH, Posterior neurohypophysis oxytocin uterus milk ADH water made in hypothalamus. Pineal melatonin sleep circadian. Thyroid T3 T4 BMR growth calcitonin ↓ Ca2+, Parathyroid PTH ↑ Ca2+ bone resorption gut kidney Ca2+ absorption antagonistic. Tetany low Ca2+.

3. Adrenal Pancreas Gonads - Emergency and Sugar Managers

Adrenal gland cap on kidney like hat. Cortex outer 80-90% steroid, Medulla inner 10-20% adrenaline.

Story - Emergency Department: Adrenal cortex has 3 zones: Mineralocorticoids aldosterone salt-water balance Na+ retention K+ excretion BP ↑, Glucocorticoids cortisol ↑ blood sugar gluconeogenesis anti-inflammatory long-term stress, Sex corticoids androgens. Medulla adrenaline epinephrine noradrenaline emergency hormone fight flight rapid. Thymus in upper thorax behind sternum thymosin T-cell differentiation cell-mediated immunity active in childhood involutes with age. Pancreas mixed gland exocrine acini digestive enzymes and endocrine Islets of Langerhans 1-2 million. Beta cells 70% insulin ↓ blood sugar uptake glycogenesis, Alpha 20% glucagon ↑ blood sugar glycogenolysis gluconeogenesis, Delta somatostatin inhibits both. Blood sugar normal 70-110 fasting 140 postprandial. Gonads: Testes Leydig interstitial cells testosterone spermatogenesis secondary characters beard voice, Ovaries Graafian follicle estrogen growth, Corpus luteum progesterone maintains pregnancy. Testosterone estrogen antagonistic but both needed.

Part 3A - Pancreas Alpha Beta Insulin Glucagon & Gonads

Part 3B - Hormone Mechanism Second Messenger Zoom

Revision: Adrenal cap cortex 80-90% Mineralocorticoid aldosterone Na+ K+ BP, Glucocorticoid cortisol sugar anti-inflammatory stress, Androgens, Medulla 10-20% adrenaline noradrenaline emergency fight flight. Thymus thymosin T-cells childhood. Pancreas Islets Alpha glucagon ↑ sugar Beta insulin ↓ sugar Delta somatostatin, 70-110 fasting. Testes Leydig testosterone, Ovaries estrogen progesterone corpus luteum.

4. How Hormones Talk - Lock Key and Second Messenger

Water soluble hormones cannot enter cell needs surface receptor like visitor needs reception. Lipid soluble can enter directly like VIP.

Creative - WhatsApp vs Letter: Water soluble peptide insulin adrenaline binds membrane receptor activates G-protein GDP→GTP, G-protein activates adenylate cyclase converts ATP→cAMP second messenger, cAMP activates PKA protein kinase A phosphorylates enzymes rapid action secretion enzyme activation. Another pathway IP3-DAG-Ca2+ phospholipase C splits PIP2→IP3+DAG, IP3 releases Ca2+ from ER Ca2+ + calmodulin activates PKC. Lipid soluble steroid cortisol estrogen diffuses across lipid bilayer binds intracellular receptor in cytoplasm forms hormone-receptor complex enters nucleus binds HRE hormone response element on DNA activates transcription mRNA→translation new protein slow long-lasting hours-days gene activation. So peptide fast second messenger, steroid slow gene activation. Think peptide as WhatsApp instant, steroid as letter takes time but long effect.

Part 4A - Feedback Negative Positive HPA HPT Axis

Part 4B - Disorders Dwarfism Acromegaly Cretinism Zoom

Revision: Water soluble surface receptor G-protein cAMP PKA or IP3 DAG Ca2+ PKC rapid second messenger enzyme activation. Lipid soluble intracellular receptor hormone-receptor complex nucleus HRE DNA transcription translation new protein slow gene activation hours-days. Feedback negative most hormones positive oxytocin LH surge.

5. Disorders - When Letters Go Wrong & Diabetes Drama

Too little or too much hormone causes disorder. GH hypo childhood dwarfism short stature, hyper childhood gigantism tall 8 feet, hyper adult acromegaly gorilla face large hands. Thyroid hypo infant cretinism stunted mentally retarded, hypo adult myxoedema puffy face, hyper Graves exophthalmic goitre bulging eyes.

Story - Drama Queens: Parathyroid hypo PTH low Ca2+ tetany carpopedal spasm Chvostek sign. Adrenal hypo Addison bronze pigmentation low BP, hyper Cushing moon face buffalo hump high BP sugar. Diabetes mellitus sweet urine: Type 1 autoimmune beta destroyed no insulin juvenile needs insulin injection, Type 2 insulin resistance adult obesity lifestyle needs tablets exercise. 3 Ps polyuria polyphagia polydipsia weight loss fatigue blurred vision slow wound healing. Hyperglycemia high sugar, Hypoglycemia low sugar dangerous sweating fainting. Blood sugar regulation insulin ↓ glucagon ↑ seesaw. HPA axis hypothalamus CRH → pituitary ACTH → adrenal cortisol → negative feedback, HPT TRH→TSH→T3 T4 negative feedback, HPG. Negative feedback most hormones like thermostat, Positive feedback oxytocin labor contractions and LH surge ovulation.

Part 5A - Diabetes Type1 Type2 Insulin Glucagon Seesaw

Part 5B - Final Summary Table All Glands Hormones Targets Zoom

Revision: GH hypo dwarfism hyper gigantism childhood acromegaly adult, Thyroid hypo cretinism infant myxoedema adult hyper Graves exophthalmic bulging eyes, PTH hypo tetany low Ca2+ spasm, Adrenal hypo Addison bronze hyper Cushing moon buffalo high BP sugar. Diabetes Type1 no insulin juvenile injection Type2 resistance adult tablets, 3Ps polyuria polydipsia polyphagia, Insulin ↓ sugar Beta Glucagon ↑ Alpha. HPA CRH ACTH cortisol negative feedback, HPT TRH TSH T3 T4, Positive oxytocin LH surge.