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Airways Notes

Medicine Notes > Respiratory System Notes

This is an extract of our Airways document, which we sell as part of our Respiratory System Notes collection written by the top tier of Bristol University students.

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Lecture 4 Airways


Describe the structure of the airways and alveoli





Explain the function of the conducting zone and respiratory zones o Conducting zone
? Made up of

* Nose

* Pharynx

* Larynx

* Trachea o Ciliated Pseudostratified, columnar epithelium o Lamina propria=where immune cells are

* Bronchi

* Bronchioles o No cartilage o Kept open by radial traction (COPD= decreased traction_

* Terminal bronchioles
? Series of interconnecting cavities & tubes both outside and within the lungs
? Function is to filter, warm, and moisten air and conduct it into the lungs o Respiratory zone
? Site of O2 and CO2 exchange with the blood
? Respiratory bronchioles and the alveolar ducts =10% Alveoli = 90%
? Alveoli

* Look same, but functionally very different depending on position Describe the protective reflexes o Sneezeo Gago CoughDescribe the function of Clara cells, type 1 & 2 pneumocytes, alveolar macs &
fibroblasts o Clara cells
? Dome-shaped cells with short Microvilli




? Found in small airways (bronchioles) of lungs
? May secrete glycosaminoglycans to protect bronchiole lining o Type I pneumocytes
? Simple squamous alveolar cells (large, thin)
? Responsible for gas exchange in alveoli
? Cover majority of surface area
? Not as numerous (half) ad type II o Type II pneumocytes
? Granular and cuboidal
? Produce surfactant to reduce tension (Respiratory Distress Syndrome of Newborn in premature babies without it) o Alveolar macrophages
? Eat bacteria, clean off particles such as dust and microorganisms from respiratory surfaces
? Engulf mycobacterium tuberculosis (but bacteria live/thrive in macs) o FibroblastsState the relationship between pressure, flow and resistance o Poiseuille's Law R = 8hl pr4

* R Resistance of tube

* h Viscosity

* l Length

* r Radius
? Radius (and therefore resistance) of bronchi depends upon

* Smooth muscle tone

* Lung volume (larger volume pulls open airways by radial traction) Explain why resistance to flow is greater in trachea and medium sized bronchi than terminal bronchioles o Resistance not very high in bronchioles usually (like tying lots of straws together) o Cancer/tumours increases resistance Describe and explain effect s of acetylcholine, adrenaline, histamine & CO2 on bronchial smooth muscle and airflow o Acetylcholine (PSNS)
? Smooth muscle contraction
? Bronchoconstriction
? Muscarinic receptors
? Treat asthma with ANTIMUSCARINICS (e.g. ipratropium) o Adrenaline (SNS)
? Smooth muscle relaxation
? Bronchodilation
? B2-adrenoreceptor
? Salbutamol activates this by binding receptor (ventolin inhaler, also labour) o Histamine
? Bronchoconstriction
? H1 receptors, smooth muscle o CO2
? Bronchodilator

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