Oesophagus

4 LAYERS OF OESOPHAGEAL WALL

• Mucosa : lined by non keratinised stratified squamous epithelium
• Submucosa :
• Muscularis externa : Toughest layer;Upper 1/3 has skeletal muscle;lower 1/3 has smooth muscle;middle 1/3 has both skeletal and smooth muscles
• Serosa

4 CONSTRICTIONS OF OESOPHAGUS

• @ 15cm (from incisors)>> @ pharyngoesophageal jn>>c6 level
• @23cm>> @ crossing of arch of aorta
• @27 cm>> @ left bronchus crossing
• @40cm>> @ piercing of diaphragm

5 BLOOD SUPPLY

• Bronchial artery
• Inferior thyroid artery
• Descending thorasic aorta
• Left gastric artery
• Left inferior phrenic artery

6 LENGTH OF OESOPHAGUS

• 15cm

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Special cells in kidney

JUXTAGLOMERULAR APPARATUS

1. Macula densa :

• In DCT close proximity to afferent and efferent arteriole
• Senses na & cl in filtrate and accordingly causes vasoconstrictionnor dilatation

2. JG cells :

• In smooth muscles of afferent arteriole
• Secrete renin

3. Lacis cells :

• @ junction of afferent and effsrent arteriole

SECRETORY CELLS OF KIDNEY

1. JG cells : secrete renin

2. Type 1 medullary interatitial cells : secrete prostaglandins

SPECIAL CELLS OF COLLECTING TUBULES

1. P-cells(principal) : 

• Na absorption
• Vasopressin mediated water reabsorption

2. I-cells(intercalated) :

• Acid sectertion 
• Hco3 transport

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Special Cells in CNS & Respiratory system

NEUROGLIAL CELLS

4 types of neuroglial cells

1) Astrocytes

• Fibrous astrocytes : found in white matter
• Protoplasmic astrocytes : found in grey matter
• Pituicytes : found in neural part of pituitary gland
• In fibrous astrocytes : glial intermediate filament is present.When CNS injury occurs -->cells producing GFAP(glial fibrillary astrocyte protein) are increased in number and size-->produce GFAP-->forms glial intermediate filament-->astrogliosis(fibrous scar)

2) Oligodendrocytes

• produce myelin sheath in CNS(in PNS myelin sheath is produced by schwann cells)
• 1 oligodendrocyte cell can ensheath upto 50 axons (1 schwan cell can ensheath 1 axon)

3) Microglial cell

• Phagoctic function in CNS(whole nevous system is ectoderm derived except microglial cell and duramater which are mesoderm)

4) Ependymal cell

• Lines CNS cavity i.e. ventricles and central canal of spinal cord

GITTER CELLS/HORTEGA CELLS

• Modified microglial cells 
• Lipid laden microglial cells found at the edge of healing brain infarcts
• They are lipid laden beacuse lipid released from damaged cells is phagocytosed by this cells

HOFBAUER CELLS

• Modified macrophages in placenta

LANGERHAN CELLS

• immature dendritic cells
• Found in all epidermis but easily identifiable in stratum spinosum;in lymph nodes
• Found in lungs in pathologies like histoplasmosis
• Immature antigen collecting cell is converted to mature antigen presenting cells>>>present antigen to MHC 1 and 2>>>activates T lymphocytes

CLARA CELLS

• In alveoli
• Produce surfactant like type 2 pneumocytes

CELLS PRESENT IN RESPIRATORY TRACT
In alveoli

• Type1 and 2 pneumocytes,
• dust cells(macrophage),
• inter alveolar pores of kohn

In conducting airway

• Goblet cells
• Basal cells
• Brush cells
• Clara cells
• Neuroendocrinal cells of kulchitsky/APUD cells

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