Iliuem transport

Question 1

Describe the steps of the sodium potassium pump

Answer 1

1) Na+ binds to carrier protein binding site and puts strain on it. ATP binds with the protein
2) ATP hydrolase catalysis the hydrolysis of ATP to ADP and Pi which puts further strain on the protein
3) Na+ leaves, protein changes shape and creates a new binding site
4) K+ ion puts strain on site, phosphate leaves the protein and it reverts to its og shape releasing the K+

Question 2

Define bulk transport

Answer 2

substance lager than a single molecule needs to enter or leave which requires ATP

Question 3

Define endocytosis

Answer 3

engulfing by cell surface membrane to form a vesicle

Question 4

Define exocytosis

Answer 4

removal of vesicle from cell

Question 5

What is the brush border?

Answer 5

Epithelial cells lining the ileum with microvilli

Question 6

How is transport increased across the ileum?

Answer 6

Microvilli

increased number of protein channels and carriers

Question 7

Describe how the transport of Na ions is involved in the absorption of glucose

Answer 7

Na+ leave epithelial cell and enter blood via active transport
Na+ concentration is lower in epithelial cell than in the small intestine
Na+ are transported into the epithelial cell via facilitated diffusion
glucose is absorbed with the Na+ against their concentration gradient

Question 8

How is the ileum adapted for absorption?

Answer 8

villi
thin walls (reduce diffusion distance)
lined with epithelial cells with a rich network of capillaries
large SA (for diffusion)
high rate of absorption

Question 9

How is the villi adapted for absorption?

Answer 9

contains muscle to move and maintain the gradient
microvilli
well supplied blood vessels
thin walls reduce diffusion
increase SA for diffusion

Question 10

How is glucose and amino acids absorbed?

Answer 10

NA+ ions move out of the epithelial cell into blood steam via active transport via the NA K pump

Higher con. of NA+ in the lumen of intestine
NA+ facilitated diffused with amino acid/glucose (co-transport) from gut to epithelial cell

Question 11

How are triglycerides absorbed?

Answer 11

In the liver lipids are emulsified into micelles via bile salts

micelles contact the epithelial cell of lumen where they break down into monoglycerides and fatty acids, as they are non-polar so can easily diffuse across

this is transported the endoplasmic reticulum where they are recombined to form triglycerides

move to Golgi apparatus to form chylomicrons( with lipids and cholesterol)

exocytosis out of epithelial cell
enter lacteals in the centre of each villi