Absorption of materials Flashcards
State the definition of diffusion
Diffusion is the movement of molecules from a higher concentration to a lower concentration down a concentration gradient
State the meaning of the term concentration gradient
A concentration gradient exists when there is a difference between the concentration of a substance in two different areas
Give examples of a substances that enter and leave body cells by diffusion.
Glucose and oxygen will diffuse into cells from a higher concentration outside the cell to a lower concentration inside the cell
Carbon dioxide will diffuse out of cells as this is a waste product of respiration
Identify substances that must be delivered to all body cells by the bloodstream for respiration
All body cells need to be supplied with oxygen and glucose, the substrates / raw materials needed for respiration
Identify the main substance that must be removed from all body cells and carried away by the bloodstream
The waste product produced by respiration that must be removed from respiring body cells is carbon dioxide
Identify the blood vessels involved in exchange of materials in body tissues
The capillaries are designed to allow exchange of materials in body tissues
State the function of the lungs
Lungs are gas exchange organs used to take oxygen into the bloodstream and remove carbon dioxide from the bloodstream
Name the structures in the lungs that provide a large surface area for gas exchange
The lungs are made up of a large number of alveoli which provide a large surface area for gas exchange
Describe the movement of gases between the alveoli and capillaries during gas exchange
Oxygen diffuses from the alveoli into the blood capillaries. Carbon dioxide diffuses from the blood capillaries into the alveoli
Describe and explain the features of the alveoli which increases the efficiency of gas exchange
The large number of alveoli creates a large surface area for gas exchange
The alveoli have very thin walls to allow efficient gas exchange over a short distance
Every alveolus is next to a blood capillary due to the extensive blood supply (dense capillary network) to ensure rapid transport f blood and re-establishment of the concentration gradient for diffusion
State the function of the small intestine
The function of the small intestine is to absorb the products of food digestion (nutrients) into the bloodstream
Identify the structures of the small intestine that provide a large surface area for absorption
The small intestine has a highly folded inner lining which is covered with finger-like projections called villi that provide large surface area for absorption of nutrients
identify the structures found inside a villus
Inside each villus there is a network of capillaries and lacteal
Describe the absorption of key nutrients from food into the structures of a villus
Inside a villus, the capillary network absorbs glucose (simplest subunit from carbohydrate digestion) and the lacteal absorbs fatty acids and glycerol (simplest sib-units from fat digestion)
Identify three common features seen in all absorption surfaces to increase the efficiency of absorption
- A large surface area
- Thin walls
- Extensive blood supply (dense network of capillaries)
