digestion and lung disease

Question 1

What is the definition of digestion?

Answer 1

The hydrolysis of large biological products to small biological molecules with the use of enzymes

Question 2

What is the definition of absorption?

Answer 2

The movement of the molecules from the lumen of the ileum, through the ieum lining into the bloodstream

Question 3

How are carbohydrates digested?

Answer 3

Saliva enters mouth from salivary glands. Salivary amylase produced in the mouth hydrolyse the glycosidic bonds in starch = maltose.

This also contains mineral salts that help to maintain the pH at around neutral (optimal pH for amylase)

enters stomach and the acid denature the amylase and prevents further hydrolysis of the starch

food passed into small intestine, mixes with pancreatic juice, which has pancreatic amylase, continues the hydrolysis of remaining starch to maltose.

Alkaline salts are produced by pancreas and intestinal wall to maintain the pH at around neutral so that amylase can function.

epithelial lining in intestine wall produces membrane- bound disaccharidase (maltase), which hydrolyses the maltose from starch breakdown into alpha glucose

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Question 4

What are membrane bound disaccharidases?

Answer 4

maltase that are not released into the lumen of the ileum but is part of the cell-surface membrane of the epithelial cells that line the ileum

Question 5

How are lipids digested?

Answer 5

They begin digestion in the small intestine

bile salts produced in the liver, stored in the gall bladder, are secreted into the small intestine and emulsify lipids into micelles (tiny droplets) to increase SA of lipids= greater access for lipases

lipases produced in the pancreas are secreted into the small intestine. This hydrolyses the ester bond found in triglycerides to form fatty acids and monoglycerides.

Question 6

Why is emulsification useful?

Answer 6

because it increases the surface area of the lipids so that the action of lipases is speeded up

Question 7

How are proteins digested?

Answer 7

Begin digestion in the stomach by endopeptides (hydrolyse peptide bonds in the middle of polypeptides) and break down the polypeptides into smaller peptide bonds

HCL in the stomach maintains the optimum pH for these enzymes

In the ileum of the small intestine where exopeptides released from the pancreas (hydrolyse the peptide bonds found at the ends of polypeptides) = many dipeptides

membrane-bound dipeptidases will hydrolyse the peptide bonds within the dipeptides = amino acids

Question 8

What are the adaptions of the villi?

Answer 8

• very thin-walled = reducing the distance over which diffusion takes place
• Contain muscle and are able to move = maintains diffusion gradient as their movement mixes the content of the ileum = ensures that new material rich in the products of digestion replaces it
• rich blood supply = blood can carry away absorbed molecules and maintain diffusion gradient
• microvilli further increases absorption.

Question 9

Absorption of triglycerides?

Answer 9

1. Micelles (which contains monoglycerides and fatty acids surrounded by bile salts) help to move monoglycerides and fatty acids towards epithelium
   
   • ∵ micelles constantly break up and reform they can ‘release’ monoglycerides and fatty acids = allows them to be absorbed
     
     • the monoglycerides and fatty acids are lipid-soluble = can diffuse directly across the epithelial cell membrane
2. Monoglycerides and fatty acids are transported to ER & combine to form triglycerides
3. Starting in the ER and continuing in the Golgi body, Triglycerides associated with cholesterol and lipoproteins = form chylomicrons (lipid transport structures) and are packaged in vesicles
4. Chylomicrons enter lacteal (part of lymphatic system) by exocytosis
5. Only drain into bloodstream near heart

Question 10

What are chylomicrons?

Answer 10

special particles adapted for the transport of lipids.

Question 11

What are the risk factors for diseases?

Answer 11

smoking

occupation

air pollution

genetics

Question 12

What is the difference between forced expiration and expiration that is not forced?

Answer 12

Quiet respiration depends on elastic recoil of the lungs after inspiratory stretching and the relaxation of the inspiratory muscles.

In forced expiration the abdominal muscles contract with force, causing the diagram to push up further and depressing the rib cage to further reduce lung volume.

Question 13

Explain what happens to the respiratory system when an asthma attack occurs (based on exam question) 4 marks

Answer 13

Bronichles contract

walls of bronchi secrete more mucus

diameter of airways is reduced

reduces airflow

Question 14

What happens : pulmonary fibrosis?

Answer 14

• Epithelial lining of the lungs becomes scarred and irreversibly thickened
• Less elastic in the alveoli
• Scarring makes your lungs stiffer and less elastic so they’re less able to move and take oxygen from the air you breathe.
• reduces tidal volume = less air can be inhaled
• forced vital capacity is reduced = smaller volume of air can be forcefully expired

Question 15

What happens: pulmonary turbulocis

Answer 15

immune system cells build a wall around the turbulocis bacteria in the lungs, forming hard lumps (tubercles)

infected issue within the tubercles dies and gaseous exchange surface is damage = tidal volume is decreased

also causes fibrosis

Question 16

What happens: Emphysema?

Answer 16

• Develops as a result of smoking
• The elastin in the lungs is permanently stretched and can’t spring back
• Walls of the alveoli can break down

Question 17

Suggest how the chylomicrons leave the epithelial cell. Give a reason for your answer.

Answer 17

Exocytosis = too large

Question 18

One of the severe disabilities that results from emphysema is that walking upstairs becomes difficult. Explain how a low FEV1 could cause this disability (exam question - 3 marks)

Answer 18

• less co2 removed
• less oxygen uptake
• less aerobic respiration/ ATP

Question 19

Explain three ways in which an insect’s tracheal system is adapted for efficient gas exchange (3 marks)

Answer 19

• tracheoles have tin walls so short diffusion distance to cells
• highly branched/ large number of tracheoles so short diffusion distance to cells and large surface area
• Trachae provide tubes full of air so fast diffusion
• fluid in the end of the tracheoles that move out during exercise so faster diffusion through the air to the gas exchange surface
• the body can be moved to move air so maintains diffusion gradient

Question 20

When there is an increase in the temperature of the water, there’s a lower concentration of oxygen and Fish increase their ventilation rate. Explain the advantage of this (3 marks) (exam questions)

Answer 20

conc of oxygen falls = less oxygen enters lamellae

blood oxygen concentration falls

advantage= maintains flow of oxygen and diffusion as well as maintains respirtation

Question 21

How does CO2 make the pH lower (more acidic)

Answer 21

CO2 dissolves in the blood forming acid = increase in H+ ions

Question 22

Describe gas exchange when insects need more air

Answer 22

contraction of muscles in insects squeezes = increase the pressure inside = CO2 forced out down a pressure gradient, and due to the spiracles being closed for a moment there is a higher pressure of oxygen on the outside= mass movements of air in and out= fast gas exchange as oxygen diffuses down pressure gradient