Lecture #30 - Absorption

Question 1

What is the process of abs? (3)

Answer 1

-

Question 2

What’re the sites of abs and what gets abs in each of the places?

Where do you find transporters?

Answer 2

-

Question 3

3 factors affecting abs:

1. Motility:
   - correct rate of propulsion for _____ and _____
   - exposure to ____ _____
   - why keep moving material?
2. Available ____ ____
   - rate of abs prop to what?
   - what is done to maximise SA?
3. Passage of molecules across available ____ ___
   - What’s the problem?
   - So what are the two pathways?
4. Removal of substances from what?
   - need large ____ flow to maintain….
   - arrangement of vessels in ____
   - position of lacteal - where is it?

Answer 3

–

Question 4

3. contd

Paracellular pathway:

1. What is the barrier?
2. Relatively non-_____
3. What is it dependent on? And requires what?
4. What are the two functions of tight junctions?

Cellular pathway:

1. Solutes must cross what?
2. They’re lipid bilayers so non-lipid soluble substances require what?
3. What are two properties of transport proteins?

Answer 4

-

Question 5

To maximise abs across SA:

Do/have what two things?

Answer 5

-

Question 6

Water:

1. How much water do we deliver to SI per day and how much do we lose so how much is recovered?
2. Mechanism for water abs:
   - O____
   - ____ movement of water from lumen into blood
   - what gradient set up by what?
   - Explain the yellow highlighted bits

Answer 6

-

Question 7

Sodium:

1. What two ways can it be absorbed? Which one isn’t as efficient?
2. What are the 3 transport mechanism for active abs of Na? Describe number one with the diagram on slide 19. For the other two (abs of glucose and aa’ - read p922 of book)

Answer 7

-

Question 8

Abs of products of fat digestion:

1. The products are ___ soluble
   - so can ____ cross cell membrane into cell
   - don’t need what?
   - delivered to brush border by what?
2. Is the whole micelle abs?
   - what diffuses into cell?
3. In cell:
   - resynthesises into what?
   - packaged into what?
   - how does that exit and what does it enter?

Answer 8

-

Question 9

How and where are bile salts absorbed? (majority of them are reabs, js)

Answer 9

-

Question 10

Absorption of vitamins:

1. Fat soluble vitamins
   - what are the 4
   - absorbed with what?
   - yellow bit says how they’re abs
2. Water soluble vitamins:
   - two of them and two types of abs
   - they need transports

Absorption of Vit B12:

1. Involves ____ ___ secreted by gastric glands in stomach
2. Three steps on how it works
3. Active or passive?

Answer 10

-

Question 11

Elimination:

1. Expulsion of residues of digestion
   - what’s formed in the LI?
   - transferred to rectum via?
   - how are faeces eliminated from body?

Answer 11

-