Flashcards in CO-TRANSPORT Deck (35)
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1
What are co-transporters a type of
carrier protein
2
What do co-transporters do
bind 2 molecules at a time
3
How do co-transporters work
they use to concentration gradient of one of the molecules to move the other against its own concentration gradient
4
How are sodium and glucose co-transported
sodium ions move into the cell down their concentration gradient and glucose moves into the cell against concentration gradient
5
What is the role of diffusion in absorption
proteins & carbohydrates are being digested continuously, so there is a greater conc of glucose & amino acids in the ilium than blood, so glucose moves down the conc gradient from the ilium to the blood which is moved away via circulation, maintaining the conc gradient.
6
How can you increase the rate of movement across membranes (2 points)
1) increased surface area (villi/microcilli)
2) increased number of protein channels/carrier proteins
7
What are villi
projections of the wall of the illium
8
What are microvilli
projections of the cell-surface membrane of the epithelial cells that line the wall off the illium
9
What method are amino acids and glucose absorbed from the small intestine into the blood
co-transported
10
What molecule is glucose/amino acid co-transported into the blood with
sodium
11
How is glucose/amino acid co-transported from small intestine (5 points)
1) sodium ions are actively transported out of the epithelial cells into the blood through the sodium-potassium pump (takes place in one type of protein-carrier molecule in the cell surface membrane of epithelial cells)
2) this maintains a higher concentration gradient of the sodium ions in the lumen of the intestine than the inside the epithelial cells
3) sodium ions diffuse down this conc gradient through a different type of protein carrier (sodium-glucose co-transporter protein), carrying either amino acid or glucose molecules into the cell with them as they diffuse
4) the conc of amino acids/glucose increases
5) so amino acids/glucose diffuses out of the cell into the blood down conc gradient through protein channel by facilitated diffusion
12
What conc gradient does sodium & amino acid/glucose move along in co-transport
sodium = down
glucose = against
13
What type of active transport is co-transport of sodium & amino acid/glucose (indirect/direct)
indirect
14
Why is the co-transport of sodium & amino acid/glucose an indirect form of active transport
the energy comes from the sodium ion concentration gradient rather than ATP
15
What is a treatment for diarrhoea
oral rehydration therapy
16
What are the causes of diarrhoea (3 points)
1) damage to the epithelial cells lining the intestine
2) loss of microvilli due to toxins
3) excessive secretion of water due to toxins (e.g cholera toxin)
17
What is the result of diarrhoea
dehydration
18
Why is just drinking water ineffective for curing diarrhoea (2 points)
1) water is not being absorbed from the intestine
2) drinking water does not replace the electrolytes (ions) being lost from the intestinal cells
19
What 'drink' (rehydration solution) can be made to help diarrhoea
one that contains a suitbale mixture of substances that will be absorbed by the small intestine
20
How does the 'drink' (rehydration solution ) work if the small intestine is not absorbing water
it uses the alternative pathways of the other type of carrier protein in the plasma membrane of epithelial cells that absorbs sodium ions
21
What does the rehydration solution need to contain (5 points)
1) water
2) sodium ions
3) glucose
4) potassium ions
5) other electrolytes
22
Why is water required in the rehydration solution
to rehydrate tissues
23
Why are sodium ions required in the rehydration solution
to replace the sodium ions lost from epithelium of intestine, and optimise use of althernative carrier proteins
24
Why is glucose required in the rehydration solution
to stimulate the uptake of sodium ions from the intestine, and provide energy
25
Why are potassium ions required in the rehydration solution
to replace lost potassium ions and stimulate appetite
26
Why are other electrolytes required in the rehydration solution
to help prevent electrolyte imbalance, and a condition called metabolic acidosis
27
What are examples of the other electrolytes required in the rehydration solution (2 points)
chloride ions, citrate ions
28
Does oral rehydration therapy cure diarrhoea
no
29
Were there any side effects and what were they caused by
yes especially in children, caused by excess sodium
30
What was tested to overcome the side effects, and what was the issue created
solutions with lower sodium ion content and higher glucose, the extra glucose lowered the water potential in the lumen of the ilium so that it started drawing more water from the epithelial cells
31
What was tested to overcome the issues created with the solution to the side effects
use starch in place of glucose
32
Why was starch a choice for overcoming the issues created with the solution to the side effects
it is steadily broken down into glucose monomers by amylase and maltase
33
Which type of starch was favoured for tested overcoming the issues created with the solution to the side effects and why (2 reasons)
rice starch
1) readily available in many parts of the world (espeically those diarrhoea is common)
2) provides other nutrients such as amino acids, that are nutritionally valuable & help uptake of sodium ions
34
How many stages of testing drugs are there usually
4
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