Lecture 18 Flashcards
What is the respiratory minute volume formula?
Respiratory minute volume = Tidal volume x Respiratory rate
What does the respiratory minute volume formula measure?
How much air we can breath in and out
What is dead space
The volume of air that gets stuck in the tract and doesn’t make it to the alveoli
What is the dead space formula?
Alveolar ventilation = (Tidal volume - dead space) x respiratory rate
Why are tiny rapid breaths unhelpful?
Because of the dead space, air is not getting to the alveoli
What is daltons law?
The pressure of a mixture of gases is the sum total of the pressures of each individual gas
What direction does oxygen travel?
From the alveoli to the capillaries
What direction does carbon dioxide travel?
From the capillaries to the alveoli
What are the three things that determine the rate of diffusion across the alveoli membrane?
The surface area of the membrane, the thickness of the membrane and the pressure difference between the two sides
What is the shape of the alveoli and what does this do for the surface area?
Bulbous structure (+ high density of capillaries covering them) which enhances surface area for gas exchange
What is emphysema?
A disease characterised by the dilation of the alveolar spaces and destruction of the alveolar walls which reduces the surface area making less contract between air and capillaries so the exchange is greatly reduced
What is the blood air barrier?
The alveolar and capillary walls which is very small for easy diffusion
What does pulmonary fibrosis do?
It is the thickening and scarring of alveolar membranes making the blood air barrier much thicker
Is the pressure difference between the alveoli and capillaries dynamic or fixed?
Dynamic
Why does low activity require less oxygen?
Reduced consumption leading to higher levels in the venous system = little difference and little pull between the two sides
