Respiratory System Summary Notes PDF

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Respiratory System Summary NotesRespiratory System: The respiratory system consists of a conducting portion and a respiratory portion. The conducting portion provides a passageway for air and functions to condition the incomingair, by warming, moistening and cleaning it.o It consists of the nasoph...

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1 Respiratory System Summary Notes Respiratory System:  The respiratory system consists of a conducting portion and a respiratory portion.  The conducting portion provides a passageway for air and functions to condition the incoming

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air, by warming, moistening and cleaning it. o It consists of the nasopharynx, larynx, trachea, bronchi, bronchioles and terminal bronchioles. (We omit the nasopharynx and larynx in this module.) The respiratory portion serves to rid the body of carbon dioxide and pick up oxygen. o It consists of respiratory bronchioles, alveolar ducts and alveolar sacs. All of these structures bear alveoli, the tiny air sacs in which the gas exchange takes place.

Functions  Two primary functions: conduction, and exchange of gaseous substances  Besides primary function, it has a role in phonation, body temperature regulation, excretion, olfaction Respiratory Epithelium

Respiratory Epithelium 1. From Trachea to Alveolar Sacs a. decrease in size b. change in cell types c. decrease in complexity 2. Pseudo Stratified Ciliated Columnar Epithelium, W/goblet Cells 3. Ciliated Columnar Epithelium, No goblet Cells 4. Ciliated Cuboidal Epithelium, No goblet Cells 5. Simple Squamous Epithelium

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Trachea → Bronchi → Secondary bronchi  tertiary bronchi  bronchioles  terminal bronchioles →respiratory bronchioles →alveoli

Trachea - The trachea is a flexible tube that extends from the larynx into the thorax. Its main function is to act as a conduit for air, but it also helps condition the inspired air.

Oesophagus Trachea

Histology of the Trachea -four layers: a mucosa (epithelium and lamina propria), a submucosa, a fibrocartilage layer and an adventitia Mucosa - consists of a pseudostratified, ciliated, columnar epithelium, with abundant goblet cells and with a very elastic lamina propria.  the respiratory epithelium also contains brush cells, endocrine cells (or small granule cells, 

function not clear), surfactant producing cells (or Clara cells), and serous cells. The lamina propria consists of loose connective tissue with many elastic fibers, which condense at the deep border of the lamina propria to form an elastic membrane. This elastic membrane forms the border between the mucosa and the connective tissue below it (submucosa).

Submucosa - consists of loose connective tissue with numerous mixed (serous and mucous) glands.  Ducts from these glands open toward the lumen. Particles get entrapped in the mucus which floats on the serous secretions. Cilia on the epithelial cells direct the secretions toward the oral cavity, where they can be swallowed or spat out.

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The boundary between the mucosa and the submucosa is not obvious. Special stains would reveal an abundance of elastic fibres at this boundary.

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The submucosa ends with the perichondrium of the tracheal cartilages. of a series (16-20) of C-shaped cartilage rings which prevent the trachea ed by a band of dense connective tissue called a perichondrium. The with the submucosa and the adventitia. ends of the C are joined by a band of smooth muscle. Contraction of this cheal diameter and increases intrathoracic pressure during coughing. The is occupied by fibroelastic connective tissue. ve tissue that binds the trachea to adjacent structures in the neck and gest blood vessels, nerves and lymphatics.

Trachea

chioles des into two primary bronchi that enter the lungs. Within the lung, the mediately divide into secondary (or lobar) bronchi that supply each lobe. nto tertiary (or segmental) bronchi that supply the segments of each lobe. divide to give rise to many generations of bronchi, each smaller than the

ar to trachea (Pseudostratified columnar epithelia with cilia and goblet

haped cartilage of the trachea is replaced by separate plates of cartilage. me smaller and farther apart the more distal the bronchus. (When no resent, you have a bronchiole, not a bronchus). At the same time, the omes surrounded by a band of smooth muscle. The muscle fibres that chi are arranged spirally and criss-cross one another, so they do not uous band in a cross-section. This band of smooth muscle becomes a feature as the cartilage diminishes. The smooth muscle can be considered , the muscularis, lying between the mucosa on the one side and the artilage layer (with plates) and adventitia on the other. Going distally down the bronchial tree, the lamina propria becomes reduced and the smooth muscle of the muscularis comes to lie closer to the epithelium. Serous and mucous glands are present

4 in the submucosa of bronchi, their numbers also decrease with each division into smaller orders of bronchi. (Like the cartilage, all glands are gone when bronchi branch into bronchioles.) The epithelium is similar to that of the trachea, but its height becomes reduced and goblet cells become less frequent.

Primary Bronchi

Bronchial tubes

      

Pseudostratified Ciliated Columnar Epithelium Mucous goblet Cells, Large, many; Medium, present; Small, few in number Smooth Muscle under epithelium, Spiral, crisscross, bundles of smooth muscle Mucous and Seromucous glands Plates and Islands of Hyaline Cartilage, irregular Abundant Elastic Fibers Lymphoid Nodules at branch points

Bronchioles       

5mm or less Pseudostratified Ciliated Columnar Epithelium (height becomes smaller) Scattered goblet cells No Hyaline Cartilage No submucosal Glands Lamina propria, Smooth muscle & Abundant Elastic Fibers Smooth Muscle better developed than Bronchus

5 Terminal B    

Cilia No Abu Spir

A. Respi

1. 2. 3. 4. 5. 6. B. Alveo 1. 2. 3. 4. C. Alveo 1. 2. 3. 4. D. Funct 1.

o 2.

6 c. Produce Surfactant (dipalmityl lecithin) d. Reduces surface tension & Prevents collapse of Alveoli e. Bacterialcidal effect 3. ... Dust cells, macrophages a. develope from monocytes in the blood b. found on the surface of the alveolus, in the alveolar septum c. phagocytize debris, (blood and RBCs in heart failure) d. carried in Surfactant up the mucocillary elevator to the esophagus 4. ...Other cell types (in alveolar septum) a. Fibroblasts, collagen and elastic tissue synthesis b. Mast cells c. Contractile Interstitial cells, reduce volume of alveolus 1. affected by epinephrine, histamine (When?)

Histological Organization of Respiratory Tract...