Alveolus and Respiratory Membrane

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Dale Crawford
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Alveolus and Respiratory Membrane thin membrane where gas exchange occurs in the lungs, simple squamous epithelium

They fit closely together in tissues; providing a smooth, low-friction surface over which fluids can move easily)

carbon dioxide can diffuse easily across the thin membrane. In many regions where there are no interstitial fluid.

2 Alveolus and Respiratory Membrane thin membrane where gas exchange occurs in the lungs, simple squamous epithelium (Squamous cells have the appearance of thin, flat plates. They fit closely together in tissues; providing a smooth, low-friction surface over which fluids can move easily) lining the alveoli, the endothelium of the pulmonary capillary walls and the fused basement membrane Oxygen and carbon dioxide can diffuse easily across the thin membrane. In many regions where there are no interstitial fluid. basement Membrane is Extracellular material consisting of a basal lamina secreted by epithelial cells and a reticular lamina secreted by underlying connective tissue cells.

Alveolus and Respiratory basement Membrane a thin, fibrous,

(pleural cavity, peritoneal cavity, pericardial cavity, etc) and

3 Alveolus and Respiratory basement Membrane a thin, fibrous, non-cellular region of tissue that separates the epithelium (e.g., skin, respiratory tract, gastrointestinal tract, etc), mesothelium (pleural cavity, peritoneal cavity, pericardial cavity, etc) and endothelium (blood vessels, lymph vessels, etc) from underlying connective tissue. Basement membrane is not actually a membrane; rather, it is a matrix.

4 Gas Exchange Henry s Law: The amount of gas dissolved in a liquid is determined by the pressure of the gas and its solubility in the liquid. n If the temperature stays constant, increasing the pressure will increase the amount of dissolved gas. P gas = KC (T = const) K: Henry s Constant C:concentration of the dissolved gas Note that: C 1 / P 1 = C 2 / P 2 Oxygen-Hemoglobin dissociation curve

5 Gas Exchange O 2 and CO 2 exchange by passive diffusion P O2 is 105 mmhg in alveoli and 40 in alveolar capillaries P CO2 is 45 mmhg in alveolar capillaries and 40 in alveoli

6 Gas Exchange Henry s Law: The amount of gas dissolved in a liquid is determined by the pressure of the gas and its solubility in the liquid. n If the temperature stays constant, increasing the pressure will increase the amount of dissolved gas. P gas = KC (T = const) K: Henry s Constant C:concentration of the dissolved gas Note that: C 1 / P 1 = C 2 / P 2

7 Gas Transport Hemoglobin structure and function A hemoglobin molecule can bind up to four oxygen atoms

8 Gas Transport Oxygen Dissociation Curve. Affinity for O increases after the first O adsorption until saturation.this curve is controlled by, the ph (acidity, or alkalinity), Temperature in partial pressure of CO 2 )

9 Gas Transport Factors affecting oxygen dissociation curve (in lungs membrane). This leftward shift indicates that the hemoglobin under study has an increased affinity for oxygen so that hemoglobin binds oxygen more easily, but unloads it more reluctantly. Left shift of the curve is a sign of hemoglobin's increased affinity for oxygen (e.g. at the lungs).

Gas Transport Factors affecting oxygen dissociation curve (e.g. near tissue) A rightward shift indicates that the hemoglobin under study has a decreased affinity for oxygen.

10 Gas Transport Factors affecting oxygen dissociation curve (e.g. near tissue) A rightward shift indicates that the hemoglobin under study has a decreased affinity for oxygen. This makes it more difficult for hemoglobin to bind to oxygen (requiring a higher partial pressure of oxygen to achieve the same oxygen saturation), but it makes it easier for the hemoglobin to release oxygen bound to it. The effect of this rightward shift of the curve increases the partial pressure of oxygen in the tissues when it is most needed, such as during exercise, or hemorrhagic shock Bohr effect

12 ABG Results Arterial Blood Gas Values test Control factors decrease increase Temperature left shift right shift 2.3-DPG left shift right shift p(co 2 ) left shift right shift ph (Bohr effect) right shift (acidosis) left shift (alkalosis) 2.3-DPG (bisphosphoglycerate) Acid: binds with greater affinity to deoxygenated hemoglobin Its production increases during hypoxaemia, chronic lung disease, anaemia, and congestive heart failure

airway) accompanied by destruction of the alveolar wall and without

13 Pulmonary Emphysema abnormal permanent enlargement of the airspaces distal to the terminal bronchioles (The end of the nonrespiratory conducting airway) accompanied by destruction of the alveolar wall and without obvious fibrosis (excess fibrous connective tissue in an organ ) and lost elasticity

pleural cavity Pneumothorax abnormal collection of air

14 Lung Injury - X-Ray Haemothorax collection of blood in the space between the chest wall and the lung (the pleural cavity Pneumothorax abnormal collection of air or gas in the pleural space that separates the lung from the chest

15 Respirators and Ventilators When a patient has difficulty breathing because of paralysis, neurological insufficiency, or other causes It is usually sufficient to aid only inspiration process, since the elastic contractions of the chest walls and lung are sufficient to accomplish expiration. Iron lung type respirator create negative pressure over the patient entire body except for the head thus aid the chest expansion and inspiration. Positive pressure ventilators are better. It works by entering oxygen wit pressure greater than atmospheric pressure.

16 Exercise The air in a sealed container with constant volume has a pressure of 1 atm at 0 o C. What will be its pressure at 100 o C? At what temperature will the pressure be 2 atm? (Pf = 1.37 atm, K= o C) Exercise Given 1000 cm 3 volume of gas at 27 o C, what temperature would be required for that gas to occupy a volume of 500 cm3, if the pressure were constant? (150 K) Exercise If the absolute pressure inside a balloon (closed container ) is 90 mmhg with 75 % of helium, 5 % of CO 2 and 20 % of O 2 find the partial pressures of O 2, CO 2 and helium gasses

Respiratory System Physiology. Dr. Vedat Evren

Respiratory System Physiology. Dr. Vedat Evren Respiratory System Physiology Dr. Vedat Evren Respiration Processes involved in oxygen transport from the atmosphere to the body tissues and the release and transportation of carbon dioxide produced in