Chapter 22 : Chemical Coordination NEET Short Notes PDF 2027

Hello friend 👋

NEET Biology Chapter 22: Chemical Coordination and Integration

Free Detailed Notes 📚

Pituitary + Thyroid + Adrenal + Pancreas + Hormones

PDF + Diagrams + MCQs

Want it? DM me ❤️ 

### *1. Endocrine System*

*Endocrine Glands*: Ductless glands. Secrete *hormones* directly into blood  

*Exocrine Glands*: Have ducts. Ex: Salivary, Sweat, Digestive glands  

*Mixed Glands*: Both endocrine + exocrine. Ex: Pancreas, Gonads

*Hormones*: Chemical messengers. Produced in trace amounts. Regulate metabolism

### *2. Human Endocrine System - Major Glands*

#### *A. Pituitary Gland / Hypophysis*

*Location*: Below hypothalamus. Attached by stalk  

*Divided into 3 parts:*

*1. Anterior Pituitary / Adenohypophysis*

- *Growth Hormone GH / Somatotropin*: Growth of bones & tissues. Excess → Gigantism. Deficiency → Dwarfism

- *Prolactin PRL*: Milk synthesis in mammary glands

- *TSH*: Stimulates thyroid gland

- *ACTH*: Stimulates adrenal cortex

- *Gonadotropins*: FSH + LH. Regulate gonads

- *MSH*: Melanocyte stimulation

*2. Intermediate Lobe*

- *MSH*: Skin pigmentation

*3. Posterior Pituitary / Neurohypophysis*

Stores & releases hormones of hypothalamus

- *ADH / Vasopressin*: Water reabsorption in kidney. Deficiency → Diabetes insipidus

- *Oxytocin*: Uterus contraction during childbirth, Milk ejection

#### *B. Pineal Gland*

*Location*: Brain. Secretes *Melatonin*

*Functions*: Regulates sleep-wake cycle, 24hr rhythm. Also called "Biological clock"

#### *C. Thyroid Gland*

*Location*: Neck. 2 lobes connected by isthmus  

*Hormones*: 

1. *T3 - Triiodothyronine*

2. *T4 - Thyroxine*  

   - *Functions*: Metabolism, Growth, Basal Metabolic Rate BMR

   - *Iodine required* for synthesis

   - *Disorders*: 

     - *Hypothyroidism*: Goitre, Cretinism in children, Myxoedema in adults

     - *Hyperthyroidism*: Grave's disease, Exophthalmic goitre

3. *TCT / Calcitonin*: Lowers blood Ca²⁺ level

#### *D. Parathyroid Gland*

*Location*: 4 glands on back of thyroid  

*Hormone*: *PTH / Parathormone*

*Function*: Increases blood Ca²⁺ level. Antagonist to Calcitonin  

*Disorder*: Hypocalcemia → Tetany

#### *E. Thymus*

*Location*: Chest, behind sternum. Large at birth, degenerates with age  

*Hormone*: *Thymosin*  

*Function*: Differentiation of T-lymphocytes. Immunity

#### *F. Adrenal Gland*

*Location*: Top of kidneys. 2 parts:

*1. Adrenal Medulla* - 10% 

- *Hormones*: Adrenaline / Epinephrine, Noradrenaline / Norepinephrine

- *Function*: Fight & Flight response. ↑ Heartbeat, ↑ BP, ↑ Glucose

*2. Adrenal Cortex* - 90%. 3 layers

- *Mineralocorticoids*: Aldosterone. Na⁺ & water reabsorption

- *Glucocorticoids*: Cortisol. Carbohydrate metabolism, Anti-inflammatory

- *Androgens*: Sex hormones

- *Disorder*: Addison's disease - Hypocortisolism

#### *G. Pancreas - Mixed Gland*

*Endocrine part*: *Islets of Langerhans*

1. *α-cells*: *Glucagon*. ↑ Blood glucose. Glycogenolysis

2. *β-cells*: *Insulin*. ↓ Blood glucose. Glycogenesis

3. *δ-cells*: Somatostatin. Inhibits Insulin & Glucagon

4. *F-cells*: Pancreatic Polypeptide

*Disorders*: 

- *Diabetes Mellitus*: Insulin deficiency. Hyperglycemia, Glucose in urine

- *Diabetes Insipidus*: ADH deficiency

#### *H. Testis - Male Gonad*

*Hormone*: *Testosterone* from Leydig cells  

*Functions*: Secondary sexual characters, Spermatogenesis, Anabolic effects

#### *I. Ovary - Female Gonad*

*Hormones*: 

1. *Estrogen*: Female secondary characters, Uterus growth

2. *Progesterone*: Maintenance of pregnancy

3. *Relaxin*: Pelvic ligaments relaxation during childbirth

### *3. Hormones of Heart, Kidney & GIT*

1. *Heart*: *ANF / Atrial Natriuretic Factor*. ↓ BP, ↓ Na⁺ reabsorption

2. *Kidney*: *Erythropoietin*. RBC formation

3. *GIT*: 

   - *Gastrin*: Gastric juice secretion

   - *Secretin*: Bicarbonate from pancreas

   - *CCK*: Pancreatic enzymes + Gall bladder contraction

   - *GIP*: Inhibits gastric secretion

### *4. Mechanism of Hormone Action*

*2 Types of Receptors:*

1. *Membrane-bound receptors*: Protein hormones, Adrenaline

   - *Second messenger*: cAMP

   - *Pathway*: Hormone → Receptor → G-protein → cAMP → Cellular response

2. *Intracellular receptors*: Steroid hormones, Thyroid hormones

   - *Pathway*: Hormone → Enters cell → Binds receptor → Hormone-Receptor complex → DNA → Gene expression

### *5. NEET High Yield Points*

- *Hypothalamus* is the *master regulator* of endocrine system

- *Pituitary* is called *"Master gland"*

- *Insulin & Glucagon* are antagonistic

- *Calcitonin & PTH* are antagonistic

- *ADH & Oxytocin* are both released from posterior pituitary

- *Catecholamines*: Adrenaline + Noradrenaline

- *Negative feedback* regulates most hormone secretion

### *6. Disorders Quick Revision*

Disorder Cause Symptoms

**Gigantism** Excess GH in child Abnormal growth

**Acromegaly** Excess GH in adult Large hands, jaw

**Dwarfism** GH deficiency Stunted growth

**Diabetes insipidus** ADH deficiency Excess urination

**Diabetes mellitus** Insulin deficiency High blood sugar

**Goitre** Iodine deficiency Enlarged thyroid

**Cretinism** Thyroid deficiency in child Mental + Physical retardation

**Addison's disease** Adrenal cortex deficiency Low BP, fatigue

Revise this + *NCERT Endocrine gland diagram* 2 baar. *Pituitary, Thyroid, Adrenal, Pancreas* se har saal 3-4 questions aate hain 💯