Presentation on theme: "Respiratory System ROLE: To bring oxygen into the body and to get rid of the carbon dioxide from the body."— Presentation transcript:
Respiratory System ROLE: To bring oxygen into the body and to get rid of the carbon dioxide from the body.
The respiratory system
When you breathe in: intercostal muscles between the ribs contract, pulling the chest walls up and out the diaphragm muscle below the lungs contracts and flattens, increasing the size of the chest the lungs increase in size, so the pressure inside them falls. This causes air to rush in through the nose or mouth. Mechanisms of breathing – inspiration Diaphragm contracts and moves down Intercostal muscles pull ribs up and out
Mechanisms of breathing – expiration When you breathe out: Intercostal muscles between the ribs relax so that the chest walls move in and down. The diaphragm muscle below the lungs relaxes and bulges up, reducing the size of the chest. The lungs decrease in size, so the pressure inside increases and air is pushed up the trachea and out through the nose or mouth. Diaphragm relaxes and bulges up Ribs move in and down
Mechanisms of breathing – inspiration
Mechanisms of breathing – expiration
The respiratory system
Respiratory system – 3 main processes Pulmonary respiration –The breathing of air into and out of the lungs External respiration –Exchange of O2 and CO2 between the lungs and the blood Internal respiration –Exchange of O2 and CO2 between the blood and muscle tissues
Gaseous Exchange Gaseous exchange refers to the exchange of gases, namely O2 and CO2 and relies on a process called diffusion
How does Diffusion happen? PP – partial pressure of a gas is the pressure it exerts within a mixture of gases. EXAMPLE: -Air – Nitrogen (79%); Oxygen (21%); Carbon Dioxide (0.03%) -Together they exert a pressure of 760mmHg but individually they exert pressures of: -O2 – 160mmHg -How do you work it out? – -Partial Pressure = Atmospheric pressure x fractional concentration -760mmHg x 0.21 = 159.6mmHg * Gases always move from an area of high pressure to an area of low pressure
Diffusion Diffusion is the movement of gases from an area of high pressure to an area of low pressure. The difference between the high and low pressure is called the diffusion gradient – the bigger the gradient, the greater the diffusion and gaseous exchange that takes place.
Gas exchange at the alveoli
External Respiration (Alveoli) – What makes it so efficient? 1.Alveoli walls very thin – diffusion distance is very short. 2.Huge amount of alveoli with massive surface area for diffusion 3.Vast supply of capillaries – huge surface area for diffusion 4.Diameter of capillaries is slightly narrower than area of red blood cells A)Causes red blood cells to distort to increase surface area for gas exchange B)Forces red blood cells to go through capillaries in single file to maximise exposure to oxygen
Internal Respiration (muscles) – why is it so efficient? Big diffusion gradient (65mmHg) Myoglobin in muscles has a higher affinity for oxygen than haemoglobin sp attracts oxygen from blood Extensive capillary network – huge surafce area Capillary wall only one cell thick – very short distance for diffusion