The respiratory system Respiration The respiratory system

Respiration Organisms must exchange oxygen and carbon dioxide with the environment. Will look at plants and photosynthesis in ecosystems, and we have looked at cellular respiration We are now moving to the more macro level of systems including circulation (as most systems do not work in isolation). Will also look at blood in detail and at the circulation system, of plants as they too are organisms.

Exchanging gases with the environment READ 8.1 on pg 130 Diffusion – you should only need to read and refresh here Look at the extension exercise – note reason why people in higher altitude areas need more haemoglobin and red blood cells. Extension exercise – need more haemoglobin and red blood cells due to the lower levels of atmospheric oxygen

What do we already know?? Draw me a picture of a torso showing the lungs ~ label your diagram as much as you can ~ can you describe what happens in inspiration and expiration

Bronchi receives oxygen rich blood from the pulmonary aorta. Trachea (windpipe): ~2.5cm diameter ~11-12 cm long ~divides L & R Bronchi ~kept open by soft C shaped rings of cartilage Bronchi receives oxygen rich blood from the pulmonary aorta. Alveoli receives oxygen poor blood from the Pulmonary artery. Trachea lined by cartilage so they can expand when food goes down the gullet next to it and puts pressure on it. Bronchi (plural), Bronchus (single) Alveoli receives oxygen via gas exchange through thin membranes of the alveoli /capillary walls.

Lungs Surrounded by two thin sheets of tissue called the pleural membranes ~inner one covers the lungs ~outer one lines the thoracic cavity There is a narrow space between the membranes called the pleural cavity – it contains fluid This fluid is a surfactant – a compound that lowers the surface tension of a liquid. The fluid acts as a lubricant so that the two membranes can slide over one another smoothly as we breathe in and out.

The overall respiration process As we breathe in air through either the mouth or the nasal passages the diaphragm moves downwards and flattens out, which increases the size of the thoracic cavity. The intercostal muscles contract causing the ribs to swing out further expanding the thoracic cavity sideways

Continued… The increase in space means that the pressure becomes negative inside and allows us to draw air into the lungs. Inhalation is an active process and requires energy. Exhalation is passive and is a result of the recoiling of the thorax.

Tidal volume: The volume of air moved in and out with each breath Tidal volume: The volume of air moved in and out with each breath. It varies depending upon demand or need for oxygen ie. Exercising vs resting Vital capacity: This is the total amount of air that we can move in and out of our lungs. Facts: ~ we breathe in about half a litre at rest. ~ Males usually breathe between 4-5 litres and females a little lower. ~ Airways are affected by things such as smoking, by affecting the surfactant (fluid) in the lungs that keeps the alveoli from collapsing ~ If the airways are affected, can result in thickening or reducing number of alveoli making lungs less efficient in gas exchange.

Breathing Is actually controlled by the brain which registers the amount of carbon dioxide in the blood. If it is too high we could die, therefore the brain tells the body to increase the respiration rate to help rid the cells of the carbon dioxide. You will need to make a table and note all parts of the respiration system including the function Larynx, Trachea, nasal passages (sinuses/nasal cavity/turbinates), bronchi, bronchioles, alveoli, capillaries, diaphragm, intercostals Structure location function pharynx Back of throat Channels air to lungs and food to stomach Larynx