Q1: Co-transport of sodium and glucose Flashcards
Co-transport
The individual movement of molecules using a concentration gradient which has already been set up by direct active transport
Active transport
The movement of molecules or ions into or out of a cell from a region of lower concentration to a region of higher concentration using ATP and carrier proteins.
In active transport … are involved
carrier proteins which act as ‘pumps’
Which cells line the ileum?
epithelial cells
What epithelial cells lining the ileum possess?
microvilli
Microvilli
Finger-like projections of the cell surface membrane
Brush border
collective term for microvilli, as they look like bristles on a brush under the microscope
Microvilli provide
more surface area for the insertion of carrier proteins through which diffusion takes place
Two ways the rate of movement across membranes in increased
- microvilli
- increase the number of protein channels and carrier proteins in any given area of membrane (in increase their density)
Diffusion
the net movement of molecules or ions from a region where they are highly concentrated to a region where their concentration is lower
Where is there normally a higher concentration of glucose and amino acids in?
the ileum or the blood?
why?
the ileum,
carbohydrates and proteins are being digested continuously
Movement of glucose from the ileum into the blood
down a concentration gradient
by facilitated diffusion
How is the concentration gradient between the blood and the inside of the ileum maintained?
blood is constantly circulated by the heart,
glucose absorbed into it is constantly being removed by respiring cells.
In absorption, diffusion only results in,
equal concentrations either side of the intestinal epithelium becoming equal
How are all the available glucose and amino acids absorbed?
absorbed by co-transport as well as diffusion
