Topic 8: exchange and transport

Question 1

Give two examples of exchange surfaces in humans and describe their function.

Answer 1

.the alveoli in the lungs allow carbon dioxide and oxygen to diffuse in and out of the blood stream

.the villi in the small intestine Villi allow nutrients such as glucose, amino acids, mineral ions etc to be absorbed from the small intestines into the bloodstream

Question 2

what are the three main things that affect the rate of diffusion explain why

Answer 2

.distance the less distance the quicker the rate of diffusion

.concentration difference gradient, the bigger the difference in concentration between the area that they are diffusing from to the area they are diffusing to the faster the rate of diffusion as more molecules will move across

.surface area, the more surface area there is the faster the substance can get to the other side

Question 3

Fick’s law shows the relationship of the rate of diffusion its factors

what is the equation?

Question 4

how are the alveoli adapted for efficient gas exchange

Answer 4

Their walls are only one cell thick which provides a short distance for diffusion

There are many of them giving a large total surface area

They are moist, which allows the gases to dissolve, and therefore diffuse more easily