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.
Learning Objectives
? Introduction
? Gross features
? Bronchial Tree
? Microscopic features of different part
? Functional correlations
? Clinical correlates
Introduction
? Provide molecular oxygen for cellular oxidation
? Remove carbon dioxide generated
? Vascular or circulatory transport AND Air/Gas transport
Gross Anatomy
Bronchopulmonary Segments
Continued.....
Continued.....
Functional Requirements
? The Respiratory System has tubular components for air/gas
conduction
? Plus respiratory components for gas exchange.
? Inspiratory pressure tends to collapse the conducting tubes. They
must be held open.
? Other essential functions include: warming; moistening; cleansing by
removal of particulate matter; detoxification by absorption of harmful
gases; and entrapment of harmful bacteria and viruses.
Conduction
? 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
cells (mucous secretors).
? The cilia beat rhythmically in one direction only
? Move debris and pathogen-laden mucous to the oropharynx
and mouth where it is expectorated or swallowed.
Continued.....
? Air temperature control is by the profuse capillary beds that
are beneath the epithelium
? Which warm or cool inspired air.
? Extensive venous plexus, largely replace capillaries in the
nasal cavities to modify air temperature
Trachea
Bronchus and Bronchial Tree
? The trachea typifies the
conducting system.
? The cilia are paralyzed by
cigarette smoke.
? At rest, smooth muscle
contraction decreases
tracheal (and bronchial)
diameter to decrease
respiratory dead space.
Continued......
? Bronchioles - lumen of 1mm or less in diameter.
? 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
lumen in asthma.
Bronchiole
? Bronchioles with a lumen of 1
mm or less in diameter.
? Epithelium becomes ciliated
columnar.
? Cartilage and glands disappear
? The bronchiole is held open by
the surrounding lung tissue.
? The smooth muscle may
excessively narrow the lumen in
asthma.
Bronchiole
? Bronchioles continue to
divide and decrease in size
? Terminal Bronchioles
? Respiratory Bronchioles ,
which give the alveolar
ducts, alveolar sacs and
alveoli.
Terminal and Respiratory Bronchioles
? Epithelium - non-ciliated
cuboidal and goblet cells
disappear.
? Gas exchange - in the
respiratory alveoli
? That bud from the
respiratory bronchioles.
Alveoli
? The alveoli - functional unit
? Out-pocketings of respiratory
bronchioles, alveolar ducts and
alveolar sacs.
? The most conspicuous feature of
the alveolar wall -Presence of
many small capillaries in the
septae between them.
? Opposite the septae the alveoli
are open to allow air entry.
Epithelium
? Type I are the flattened epithelial cel s
(squamous pneumocytes) that have
cytoplasmic extensions about 0.1 - 0.3
um thick and have no microvil i.
? In some areas the basal lamina of the
type I cel is fused to the capil ary
? Endothelium - possible areas of gas
exchange.
? Type I , the large alveolar cel s (granular
pneumocytes) are cuboidal without
broad cytoplasmic extensions and
occupy about 5% of the alveolar surface.
Epithelium
? Type II Cells produce Surfactant, a stabilizing, surface-active material
consisting mainly of the phospholipid lecithin.
? Surfactant is crucial to lung function
? Its high viscosity and low surface tension, stabilizes the diameter of
alveoli preventing collapse after expiration, while retaining residual
air in the alveoli after each breath;
? Because alveoli are already partially open, energy expenditure in
subsequent inspirations is much less.
Continued....
? 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
passageways.
? Their role is to clear the lungs of invading bacteria and inspired
particulate material (e.g. dust and carbon particles).
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
asthma
? Surfactant is thick in polycystic fibrosis
Emphysema
Bronchiectasis
MCQs
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
d. Number decreases in small bronchiole
This post was last modified on 05 April 2022