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Download MBBS Anatomy PPT 44 Respiratory System Histology Notes

Download MBBS (Bachelor of Medicine, Bachelor of Surgery) Human Anatomy ppt lectures Topic 44 Respiratory System Histology Notes. - anatomy ppt free download human anatomy ppt lectures, medicine notes ppt, anatomy handwritten notes pdf, mbbs 1st year anatomy notes pdf download, best anatomy notes pdf, human anatomy notes pdf, anatomy easy notes pdf, anatomy notes online, anatomy short notes, Anatomy ppt, Powerpoint Presentations and lecture notes.

This post was last modified on 05 April 2022




Learning Objectives

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? Introduction
? Gross features
? Bronchial Tree
? Microscopic features of different part
? Functional correlations

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? Clinical correlates

Introduction

? Provide molecular oxygen for cellular oxidation

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? Remove carbon dioxide generated
? Vascular or circulatory transport AND Air/Gas transport

Gross Anatomy

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Bronchopulmonary Segments


Continued.....

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Continued.....

Functional Requirements

? The Respiratory System has tubular components for air/gas

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conduction

? Plus respiratory components for gas exchange.
? Inspiratory pressure tends to collapse the conducting tubes. They

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must be held open.

? Other essential functions include: warming; moistening; cleansing by

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removal of particulate matter; detoxification by absorption of harmful

gases; and entrapment of harmful bacteria and viruses.

Conduction

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? The nasal cavity is held open by bone and cartilage.
? Most of the additional functions are carried out by

pseudostratified columnar ciliated epithelial cells and goblet

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cells (mucous secretors).

? The cilia beat rhythmically in one direction only
? Move debris and pathogen-laden mucous to the oropharynx

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and mouth where it is expectorated or swallowed.


Continued.....

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? Air temperature control is by the profuse capillary beds that

are beneath the epithelium

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? Which warm or cool inspired air.
? Extensive venous plexus, largely replace capillaries in the

nasal cavities to modify air temperature

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Trachea

Bronchus and Bronchial Tree

? The trachea typifies the

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conducting system.

? The cilia are paralyzed by

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cigarette smoke.

? At rest, smooth muscle

contraction decreases

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tracheal (and bronchial)

diameter to decrease

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respiratory dead space.

Continued......

? Bronchioles - lumen of 1mm or less in diameter.

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? The epithelium ciliated columnar.
? Cartilage and glands disappear
? Bronchiole is held open by the surrounding lung tissue.
? The smooth muscle in the wall may excessively narrow the

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lumen in asthma.




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Bronchiole

? Bronchioles with a lumen of 1

mm or less in diameter.

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? Epithelium becomes ciliated

columnar.

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? Cartilage and glands disappear

? The bronchiole is held open by

the surrounding lung tissue.

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? The smooth muscle may

excessively narrow the lumen in

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asthma.

Bronchiole

? Bronchioles continue to

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divide and decrease in size

? Terminal Bronchioles
? Respiratory Bronchioles ,

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which give the alveolar

ducts, alveolar sacs and

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alveoli.

Terminal and Respiratory Bronchioles

? Epithelium - non-ciliated

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cuboidal and goblet cells

disappear.

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? Gas exchange - in the

respiratory alveoli

? That bud from the

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respiratory bronchioles.

Alveoli

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? The alveoli - functional unit
? Out-pocketings of respiratory

bronchioles, alveolar ducts and

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alveolar sacs.

? The most conspicuous feature of

the alveolar wall -Presence of

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many small capillaries in the

septae between them.

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? Opposite the septae the alveoli

are open to allow air entry.


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Epithelium

? Type I are the flattened epithelial cel s

(squamous pneumocytes) that have

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cytoplasmic extensions about 0.1 - 0.3

um thick and have no microvil i.

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? In some areas the basal lamina of the

type I cel is fused to the capil ary

? Endothelium - possible areas of gas

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exchange.

? Type I , the large alveolar cel s (granular

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pneumocytes) are cuboidal without

broad cytoplasmic extensions and

occupy about 5% of the alveolar surface.

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Epithelium

? Type II Cells produce Surfactant, a stabilizing, surface-active material

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consisting mainly of the phospholipid lecithin.

? Surfactant is crucial to lung function
? Its high viscosity and low surface tension, stabilizes the diameter of

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alveoli preventing collapse after expiration, while retaining residual

air in the alveoli after each breath;

? Because alveoli are already partially open, energy expenditure in

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subsequent inspirations is much less.

Continued....

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? Acting as a detergent surfactant facilitates the removal of amniotic

fluid from the lungs at birth, before the first breath.

? Dust cells (macrophages) usually lie free in the alveoli and air

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passageways.

? Their role is to clear the lungs of invading bacteria and inspired

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particulate material (e.g. dust and carbon particles).




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Summary

? Massive surface area for gas exchange (75 square metres)
? As lumen decreases so do cartilage, cilia, epithelial height and mucous
? Smooth muscle controls diameter, but excessively narrowing in

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asthma

? Surfactant is thick in polycystic fibrosis

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Emphysema

Bronchiectasis

MCQs

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Question :- Which of the following is correct regarding Clara cell?
a. Ciliated secretory cuboidal cells
b. Present in larger terminal bronchiole
c. Present in smaller terminal bronchiole

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d. Number decreases in small bronchiole