External intercostal muscles and diaphragm contract, increasing the thorax and lung volume. As volume increases, pressure decreases and air from the (higher pressure) surroundings rushes into the lungs
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What are the pleural membranes?
Membranes which cover the lungs and produce a lubricant, protecting the lungs from rubbing against the ribs
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Define Pulmonary Surfactant
Lubricant secreted by the pleural membranes to lower the friction between ribs and lungs
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What are the intercostal muscles?
Antagonistic pair - external and internal
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What type of muscle are the intercostal muscles and diaphragm and why?
Smooth muscle, as breathing is an involuntary action
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Where in the respiratory tract do you find cartillage?
trachea, bronchi, nasal passages
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Where in the respiratory tract do you find smooth muscle?
Where in the respiratory tract do you find elastic fibres?
alveoli
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What are 4 features of an efficient gas exchange surface?
large surface area, short diffusion pathway, moisture, high concentration gradient
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What is the function of nasal hairs in the respiratory tract?(2)
filtration and to move air towars the lungs
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What is the function of mucus in the respiratory tract?
to catch/trap particles/ bacteria which enter the respiratory tract
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What is the function of cilia in the respiratory tract? (2)
to beat mucus and bacteria out of the tract, to direct air flow towards the lungs
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Describe the structure/ function of type 1 pneumocytes.
thin and permeable alveolar walls to create a short diffusion pathway for gas exchange (extra: 95% of the alveolus wall consists of these)
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What do type 2 pneumocytes secrete and why?
Pulmonary surfactant - to keep the inner surface of the alveoli moist & prevent them sticking & make gas exchange more efficient
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Define epidemiology
the study of incidence and causes of disease
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Name some at least 4 causes of lung cancer
Smoking, Passive smoking, air pollution, radon gas, asbestos &silica, genetics, family history, past cancer treatment, previous conditions which decrease immunity
1.Cilia are damaged &stop working 2.Mucus builds in lungs 3.Toxins (from smoke) in mucus cause inflammation of WBCs in the lungs 4.Inflamed WBCs release trypsin 5.Trypsin digests elastic fibres in lungs 6.Breakdown of alveoli walls 7. SA is decreased
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How are the elastic fibres affected by Emphysema, and why does this matter?
broken down - alveoli lose elastic recoil, making expiration difficult
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How does emphysema affect gas exchange?
Surface area of alveoli decreases, so oxygen saturation of blood falls
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