Internal Respiration

Warm Up 1 In pairs chose either inspiration or expiration. You have one minute each to describe your chosen process. You must explain…. Pressures of air in lungs and outside of body Which type of intercostals used How this changes when you exercise

Warm Up 2 A sticker will be placed on your back You have 5 questions to guess what you are. The person you are asking can only answer ‘yes’ or ‘no’ The topic is ‘Lung Volumes’

Internal Respiration Pulmonary diffusion is the process used to explain the process of gaseous exchange in the lungs- it has 2 functions Replenish blood with oxygen- can then be taken to tissues an muscles Remove carbon dioxide form the blood which has resulted from metabolic processes.

Partial Pressure of Gases The individual pressure that the gas exerts when it occurs in a mixture of gases The gas will exert a pressure proportional to its concentration within a whole gas. Partial pressures of each gas adds up to the total pressure of the gas

Air Nitrogen 79% Oxygen 20.9% CO2 0.03 % Total atmospheric pressure at sea level is 769mmHg

Partial Pressure of Oxygen Concentration of O2 is 21% and nitrogen is 79% together they exert a pressure of 760mmHg pO2 Can be calculated as follows; = Barometric pressure x fractional concentration = 760 x 0.21 = 159.6 mmHg The partial pressure of a gas explains the movement of gases within the body

???? Work out the partial pressure of nitrogen

Gaseous Exchange at the Lungs The imbalances of gases at the alveoli and the blood that causes a pressure gradient which results in a movement of gases across the membrane. It is a 2-way movement with oxygen moving from the alveoli to the blood and CO2 moving from the blood to the alveoli

Gaseous Exchange at the Lungs Partial pressure of O2 in the atmosphere is 159mmHg This drops to 105mmHg in the alveoli The diffusion gradient Blood in the pulmonary arteries has a pO2 of 45mmHg as most of the O2 has been used by the working muscles

The diffusion gradient This makes a pressure gradient of approx 60mmHg (pO2 of 105mmHg in the alveoli) This forces the oxygen to move from the alveoli to the blood until pressure is equal on both sides. High- Low

The diffusion gradient In the same way, CO2 moves from the pulmonary capillaries to alveoli There is a pCO2 of 45mmHg in the blood returning to the lungs and pCO2 of 40 mmHg in the alveoli This is a small pressure gradient 5mmHg CO2 can diffuse a lot quicker than O2.

Endurance Athletes Endurance athletes with larger aerobic capacities will have greater oxygen diffusion ability as a result of increased cardiac output, and resistance to diffusion.

Gaseous Exchange at the Muscles pO2 in blood of 100mmHg and a low pO2 in muscle of 40mmHg causes a diffusion gradient. High to Low pCO2 of 40mmHg in blood and 46mmHg in muscle causes a small pressure gradient

Oxygen dissociates from haemoglobin to travel into the muscle. Once it is on the cell it attaches to myoglobin which takes it to the mitochondria where aerobic respiration can take place Myoglobin has a higher affinity for O2 than haemoglobin and acts like an oxygen reserve so when we need more oxygen i.e. in exercise, there is a readily available source.

In Exercise The production of carbon dioxide stimulates the dissociation of oxygen from haemoglobin, and this together with greater tissue demand for oxygen increases the pressure gradients during exercise.

Exam Questions Explain how gaseous exchange occurs in the lungs (3 marks) Explain how gaseous exchange occurs in the muscle tissue Explain how this process changes during exercise