Digestion

Question 1

What is the definition of digestion

Answer 1

the breaking down of complex sugars into simpler sugars until they are small enough to be absorbed into the body through the blood stream

Question 2

what do
1. carbohydrates
2. Fats
3. Proteins
break down into?

Answer 2

1. sugars
2. lipids (fatty acids and glycerol)
3. amino acids

Question 3

what are the 6 basic functions of the digestive system

Answer 3

1. ingestion of food and water
2. mechanical break down of food
3. chemical break down of food
4. movement of food along the alimentary canal
5. absorption of food and water into blood and lymph
6. elimination of material not absorbed (faeces)

Question 4

STEP 1: Explain how 1. mechanical and 2. chemical digestion occurs in the oral cavity

Answer 4

1. mechanical
   food physically crushed by teeth increasing SA:VOL
2. Chemical
   saliva contains amylase enzyme which converts starch/carbs (polysacaride) in maltose (monosacaride)

Question 5

STEP 2: explain how the tongue works to prepare food for swallowing and how the pharynx swallows

Answer 5

tongue moves up and back pushing the BOLUS into the pharynx and down into esophagus.
swallowing = INVOLUNTARY response that occurs when bolus touches the pharynx

Question 6

STEP 3: what is the epiglottis and its function (esophagus)

Answer 6

the flap of skin that covers the entrance to trachea when food is being swallowed so that bolus is not sent down the windpipe = choking

Question 7

STEP 3: Explain how peristalsis works with muscles in the esophagus and how MUCUS helps out

Answer 7

circular muscle contracts rhythmically and pushes bolus down to stomach along a mucus lubricated esophagus (very strong)

Question 8

STEP 3: what is the cardiac sphincter and what is its function

Answer 8

a ring of muscle that acts as a one way valve that stops food going back out of stomach

Question 9

STEP 4: Explain how chemical digestion works in the stomach (chyme - gastric juices) with the help of mechanical digestion

Answer 9

glands in the stomach wall (mucosa) release HCl, pepsin and gastric lipase (tog called gastric juices) which mix with the food and saliva to make CHYME.

Question 10

STEP 4: what does pepsin enzyme and gastric lipase break down in the chyme and what does HCl do

Answer 10

pepsin enzyme (protein->peptides)
gastric lipase (fats -> fatty acids and glycerol)
HCl helps enzymes function (pH)

Question 11

STEP 4: How does chyme get churned up (mechanical digestion in stomach) what are the 3 stomach muscle types

Answer 11

waves of muscular contraction along the muscle wall churn it up

1. circular
2. oblique
3. longitudinal

Question 12

STEP 4: what is the pyloric sphincter

Answer 12

a circular muscle which regulates flow of food into small intestine from stomach

Question 13

STEP 5: what is the function of the pancreas (name some enzymes)

Answer 13

secretes enzymes through pancreatic duct into small intestine
lipases, protease, amylase, bicarbonate

Question 14

STEP 6: what does the liver do?

Answer 14

produce bile to break down large fat droplets increasing SA:VOL for lipase enzymes

Question 15

STEP 6: what does the gall bladder do?

Answer 15

bile is transported through the bile duct to be used in the gall bladder where it is stored until food enters the duodenum

Question 16

STEP 7: how long is the small intestine and what happens here

Answer 16

6m convoluted in abdomen

90% of absorption occurs here when enzymers further break down food so that nutrients can be absorbed through lining

Question 17

STEP 7: Explain the small intestine lining helps absorption and the 2 processes in which absorption occurs

Answer 17

villi and micro villi increase SA:VOL

1. Simple DIffusion - high to low through villi
2. Active Transport - as concentration gradient decreases, the food products have to be actively transported through the cell membrane using ATP

Question 18

STEP 7: where are
1. fatty acids/glycerol
2. amino acids/glucose
3. water 
absorbed in the villi

Answer 18

1. in the lacteal of the villi and inserted into the lymphatic system
2. in the capillaries
3. absorbed passively into capillaries to solidify contents

Question 19

STEP 8: what does the colon do in the large intestine

Answer 19

water and salts are reabsorbed from digested food to prevent excessive water loss.

Question 20

STEP 8: what does the rectum do in the large intestine

Answer 20

stores faeces (75% water and 25% solid)