2023 Lecture 24 Causes of Hypoxia and Hyperventilation PDF

Lecture 24 Causes of hypoxia/hyperventilation BChD I HUB 105 2023 Dept. Medical Biosciences University of the Western Cape Respiratory deficiencies The body responds differently to changes in the composition of blood as it relates to respiration. Atm...

Lecture 24 Causes of hypoxia/hyperventilation BChD I HUB 105 2023 Dept. Medical Biosciences University of the Western Cape Respiratory deficiencies The body responds differently to changes in the composition of blood as it relates to respiration. Atmospheric air starts to change as it enters the respiratory tract and finally reaching the alveoli. Alveolar air is warmed, filtered, water content increases and has www.cartoonstock.com more CO2 and less O2 than atmospheric air. As a result of incoming atmospheric air mixing with air remaining in the alveoli from the previous respiratory cycle. The quality of incoming air and the ability of the body to release O2 or CO2 within the tissues, can affect our health. http://www.zazzle.com Respiratory deficiencies Oxygen toxicity Is a condition caused by breathing pure O2 at a high partial pressure. Inspiration of high concentrations of O2 can lead to a variety of lung injuries and even destroy the delicate respiratory membrane: – generates free radicals and H2O2 (hydrogen peroxide) – destroys enzymes – damages nervous tissue – leads to seizures, coma, death Leads to Hypoxia at the tissue level. Hypoxia refers to the below normal, low level of 02 in tissues and blood. Results in increase respiration Causes severe limits on the metabolic activities in the affected area and disrupts homeostasis. Can be caused by: high altitudes, drowning, degenerative lung diseases, CO poisoning, too few RBCs, structurally abnormal or too little Hb Symptoms : cyanosis - blueness of skin and tissue necrosis (death) Respiratory deficiencies There are 4 types of Hypoxia 1. Anoxic hypoxia or Diffusion hypoxia Deficiency in O2 gas exchange in the lungs. eg suffocation or damage to alveoli respiratory membrane. 2. Anaemic hypoxia Low quantities of functioning Hb in blood. eg hemorrhage, anaemia, or CO poisoning. 3. Stagnant hypoxia Inability of blood to carry O2 to tissues fast enough. eg heart failure, circulatory blockages. 4. Histotoxic hypoxia Adequate O2 delivered to tissue, but tissues are unable to use it properly. eg cyanide poisoning, as it blocks the metabolic activity of the cells. http://www.slideshare.net Respiratory deficiencies Excessive ventilation leads to hyperventilation, results in abnormally low PCO within the body 2 known as hypocapnia as it allows more exhalation of CO2. Associated with an increase in pH of blood plasma leading to respiratory alkalosis. Which stimulates chemoreceptors to decrease respiratory rate, slow down breathing pattern and bring PCO2 back to normal. An increase of PCO2 in the blood is called hypercapnia, this causes the pH to decrease Associated with respiratory acidosis of the plasma Which stimulates the chemoreceptors to increase the breathing rate Respiratory deficiencies Respiratory acidosis an accumulation of CO2 in the arterial blood generates excess H+ (and ∴ ↓’s pH of the blood) due to H2O + CO2 H2CO3 → H+ + HCO-3 this retention of CO2 can be due to reduced gas exchange or ventilation (common in pneumonia or emphysema), rapid & shallow breathing or due to injury of the brainstem Respiratory alkalosis when CO2 is eliminated from the body faster than it can be produced, the resulting decrease in [H+] (and ∴ ↑ in the pH of the blood) is due to H2O + CO2 H2CO3 ← H+ + HCO-3 this is a common result of hyperventilation or could be due to a brain tumor or brain damage Hypoventilation, abnormally low respiratory rate, leads to build up of PCO (hypercapnia) in blood. 2 Stimulating chemoreceptors to activate the respiratory center to increase depth and rate of respiration to restore homeostasis. Revision Questions: 1. Define following: hyperventilation, hypoventilation, hypoxia, oxygen toxicity, hyper and hypo-capnia 2. What are the effects of taking in pure oxygen. 3. Explain the 4 type of hypoxia. 4. Explain the cause of respiratory alkalosis and acidosis and how the respiratory system reacts to these metabolic changes.