RESPIRATORY SYSTEM Dr Iram Tassaduq

INTRODUCTION The respiratory system consists of paired lungs and a series of air passages that lead to and from the lungs

PORTIONS OF RESPIRATORY SYSTEM Air passages of respiratory system consist of two portions Conducting portion Respiratory portion

FUNCTIONS Air conduction Air filtration Gas exchange Speech production Immune response Endocrine function

NASAL CAVITY Nasal cavities are paired chambers separated by bony and cartiliginous septum. Chambers are divided into 3 regions Vestibule Respiratory segment Olfactory segment

VESTIBULES The vestibules (the first ~1.5 cm of the conductive portion following the nostrils) are lined with a keratinised stratified squamous epithelium. Hairs, which filter large particulate matter out of the airstream, and sebaceous glands are also present

RESPIATORY SEGMENT At the transition from the vestibule to the respiratory region of the nasal cavity the epithelium becomes first stratified squamous and then pseudostratified columnar and ciliated. This type of epithelium is characteristic for all conductive passages dedicated to the respiratory system and therefore also called respiratory epithelium. Mucus producing goblet cells are present in the epithelium.

CELLS OF RESPIRATORY SEGMENT Ciliated cells Goblet cells Brush cells Small granule cells Basal cells

CELLS OF OLFACTORY EPITHELIUM

FUNCTIONS OF OLFACTORY EPITHELIAL CELLS OLFACTORY CELLS The cell membrane covering the surface of the cilia contains olfactory receptors which respond to odour-producing substances, odorants, dissolved in the serous covering the epithelium SUSTENTACULAR CELLS . The olfactory cells and their processes receive mechanical and metabolic support from supporting cells BASAL CELLS can divide and differentiate into either olfactory or supporting cells. BRUSH CELLS Columnar cells with microvilli and are specialized for transduction of general sensation on

OLFACTORY GLANDS The supporting cells and the secretion of the serous glands contain lipofuscin granules, which give a yellow-brown colour to the surface of the olfactory region.

LARYNX The wall of the Larynx consists of : Mucosa Poorly defined submucosa A series of irregularly shaped cartilages connected by joints of relatively dense fibroelastic tissue. A group of intrinsic skeletal muscles which act upon the cartilages.

LAYERS OF LARYNX

TRACHEA Short, flexible, air tube 2.5 cm 10 cm long Extent Function

TRACHEA Typical respiratory epithelium - The lamina propria - contains large amounts of elastin and aggregates of lymphoid tissue (BALT). The submucosa - contains mucous glands. C-shaped rings of hyaline cartilage - provide a semirigid supporting skeleton outside the submucosa to prevent collapse of the airway during inspiration. The adventitia - outermost fibroelastic connective tissue layer.

TRACHEAL EPITHELIUM

CELLS OF RESPIRATORY EPITHELIUM

BRUSH CELL

SMALL GRANULE CELL

LAYERS OF TRACHEA

LAYERS OF TRACHEA

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