2536918
Description
Mind Map by charharrison, updated more than 1 year ago
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Created by charharrison
over 9 years ago
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Absorption in the
small intestine
- Villi
- Thin walls, lined
with epithelial
cells
- Short diffusion distance
- Short diffusion distance
- Finger-like
projections of the
small intestine
- Increases surface area
for absorption by
diffusion
- Increases surface area
for absorption by
diffusion
- Has a rich
network of
capillaries
- Carry's away
absorbed molecules to
maintain a
concentration
gradient
- Carry's away
absorbed molecules to
maintain a
concentration
gradient
- Able to move
- Maintains steep
concentration gradient
- Maintains steep
concentration gradient
- Epithelial lining has microvilli
- Increases surface area
- Increases surface area
- Thin walls, lined
with epithelial
cells
- Role of diffusion in
absorption
- Net movement of
molecules/ions from a region
where they are highly
concentrated to a region when
their concentration is lower
- Concentration of glucose is
greater in the lumen of the small
intestine than in the blood
- Concentration gradient
- Maintained by circulation of blood
- Villi muscles contract and
relax, mixing contents of
small intestine
- Glucose-rich food is next to villi
- Glucose-rich food is next to villi
- Maintained by circulation of blood
- Concentration gradient
- Net movement of
molecules/ions from a region
where they are highly
concentrated to a region when
their concentration is lower
- Role of active transport in
absorption
- Diffusion only results in
equal concentrations of
glucose on either side of the
intestinal epithelium
- Not all available
glucose is absorbed
- Not all available
glucose is absorbed
- Glucose is absorbed by
co-transport, it is drawn in
with sodium ions (Na+)
- Mechanism
- 1. The sodium-potassium
pump transported 2 potassium
ions in and 3 sodium ions out
(to blood)
- 2. There is now a much
higher concentration of Na+
in the lumen than epithelial
cells
- 3. Sodium ions diffuse into the cell
down their concentration gradient
through a co-transport protein
- 4. As they move in they couple with
glucose molecules, drawing them into the
epithelial cell
- 5. Glucose then
passes into the
blood by
facilitated
diffusion
- 1. The sodium-potassium
pump transported 2 potassium
ions in and 3 sodium ions out
(to blood)
- As sodium moves down it's
conc. gradient, glucose
moves up it's
- ATP is used in Na+/K+ pump
- Indirect active transport of glucose
- Indirect active transport of glucose
- ATP is used in Na+/K+ pump
- Diffusion only results in
equal concentrations of
glucose on either side of the
intestinal epithelium
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