Digestive System

Question 1

What is intestinal juice?

Answer 1

Juice secreted from small intestines lining that contains digestive enzyme capable of finalizing the digestion of carbs, proteins, and lipases.
E.g. peptidases: break down peptides into amino acids
sucrase: breakdown sucrose, lactose and maltose into glucose, galactose and fructose
lipases: breakdown lipids into fatty acids and glycerol

Question 2

What do ribonuclease and deoxyribonuclease do?

Answer 2

Digest RNA and DNA

Question 3

What do lipases do?

Answer 3

Break down fats into fatty acid and glycerol

Question 4

What do amylase do?

Answer 4

Break down starch into the disaccharide maltose

Question 5

What does trypsin/protease do?

Answer 5

Splits proteins into peptides

Question 6

What is the jejunum?

Answer 6

Middle section of the small intestine. It’s lining allows for effective absorption of carbs and proteins.

Question 7

What are the six functions of digestion?

Answer 7

-ingestion
-mechanical digestion
-chemical digestion
-movement of food along alimentary canal
-absorption of food and water into lymph and blood
-elimination of material that is not absorbed

Question 8

Define digestion

Answer 8

The mechanical and chemical breakdown of food into smaller molecules that can be absorbed into the body

Question 9

What is diarrhoea?

Answer 9

Frequent defecation of watery faeces cause by the irritation of small/large intestines which in turn speeds up the process of peristalsis.
Can be caused by: a bacteria, virus, parasite, cancer, lactose intolerance

Question 10

What is constipation?

Answer 10

A condition in which defecation becomes difficult/painful with faces being hard and dry due to a long time period of sitting in the large intestine and it’s water being absorbed.
Can be caused by: lack of roughage in diet from plant matter (insoluble fibre/cellulose), emotional problems, lack of exercise

Question 11

What is the importance of soluble fibre in a person diet?

Answer 11

Found in food derived form plants, soluble fibre has been linked to, low cholesterol, low risk of heart disease and cancer

Question 12

What is excretion?

Answer 12

Removal of wastes of metabolism from the body

Question 13

How is the small intestine well suited to absorption?

Answer 13

6-7m long
-large SA:V ratio due to villi and microvilli
-highly vascularised (lots of capillaries) allowing for higher absorption of nutrients
-segmentation which brings food to villi
-absorbs 80% of all nutrients in the internal surface

Question 14

Function of the oesophagus

Answer 14

23-25 cm long
Links the pharynx to the stomach. Aids in transporting food from the throat to the stomach in a wave like motion known as peristalsis

Question 15

Function of the epiglottis

Answer 15

Flap situated in the back of the throat closing over the trachea in order to prevent food or water from entering the lungs

Question 16

Function of the cardiac sphincter

Answer 16

Stops acid reflux from occurring. Acts as a covering to prevent acid contents from the stomach getting into the oesophagus

Question 17

What is chyme?

Answer 17

Semi-fluid mass of partially digested food that leaves the stomach.

Question 18

What is mucosa?

Answer 18

Lining of the stomach containing cells specialized for secreting gastric juice and mucous.

Question 19

What is chemical digestion?

Answer 19

Breakdown of food into smaller molecules by chemicals/enzymes
mouth- salivary amylase
stomach- pepsin
small intestine- pancreatic juice: amylase, protease, lipases, nucleases
intestinal juice: lipases, amylase, peptidases

Question 20

What is mechanical digestion?

Answer 20

The physical breakdown of food into smaller molecules
- increase SA
- increase efficiency of chem digestion

Question 21

Explain chemical digestion in the mouth

Answer 21

Food is mixed with saliva secreted into mouth cavity via the salivary glands. It contains mucous to lubricate as well as salivary amylase which digest starch into disaccharide maltose.

Question 22

Explain mechanical mouth digestion

Answer 22

-ingestion
-food is broken down into smaller molecules by chewing, tearing, etc
-Tongue shapes food into bolus

Question 23

What are the types of teeth?

Answer 23

• canines (2)
• molars (6)
• premolars (4)
• incisors (4)

Question 24

What is a bolus?

Answer 24

A lump or ball like structure of food and saliva

Question 25

Explain chemical digestion in the stomach

Answer 25

-enzymes in gastric juice (pepsin) secreted by mucosa -break down amino acid bonds of protein=polypeptides -breaks down nucleac acids into RNA and DNA

Question 26

Why is absorption of nutrients into the bloodstream not possible in the stomach?

Answer 26

The internal surface is covered by a thick layer of mucus (mucosa)

Question 27

Explain mechanical digestion in the stomach

Answer 27

Achieved by waves of muscular contraction that move along the stomach wall. -conversion in a variety of ways due to 3 muscles (oblique. longitudinal, circular) -Food is churned and mixed with acidic juice to form chyme.

Question 28

Function of the ileum?

Answer 28

Last part of the small intestine. - absorbs vitamin B12, bile salts and remaining products of digestion

Question 29

Function of the gall bladder

Answer 29

Stores bile and releases it into the small intestine where bile emulsifies lipids

Question 30

How is each nutrient absorbed in the body?

Answer 30

Fatty acids and glycerol: simple diffusion (recombine to form fat droplets, enter lacteal) Water: diffusion (absorbed into blood capillaries) Simple sugars (glucose): active transport (pass through cells on villi, into blood capillaries) Amino acids: active transport (into blood capillaries)

Question 31

Ways that the villi absorbs nutrients

Answer 31

-active transport (ATP is used to take in nutrients against a concentration gradient) -simple diffusion (higher concentration of nutrient materials in interior than in cells of villi) -continual muscular movement of intestinal wall (contact)

Question 32

What are villi?

Answer 32

Projections from the internal lining of the small intestine who's structure is well suited to nutrient absorption. -single cell layering -contain lymph capillaries (lacteal) which link to the blood vessels

Question 33

How does digestion occur in the small intestine

Answer 33

Mechanical: Secreted in via bile duct. Contains no digestive enzymes but is important in emulsifying fats to increase their surface area on which the lipases can act. Chemical (pancreatic juice): Enters duodenum secreted by pancreases via the bile duct. It neutralizes acid contents in the stomach and contains digestive enzymes: amylase, trypsin(protease), lipases, and nucleases Chemical (intestinal juice): Secreted from lining and contains enzymes that complete digestion of carbs, proteins, and lipases. Contains digestive enzymes: peptidases, sucrase, lactase, maltase, lipases

Question 34

Digestive enzymes and their products:

Answer 34

Sucrase-sucrose into monosaccharide glucose Lactase- lactose into fructose Maltase- maltose into galactose Amylase- starch into disaccharide maltose Trypsin (protease)- proteins into peptides Peptidases- peptides into amino acids Lipases- fats into fatty acid and glycerol Nucleases- digest RNA and DNA

Question 35

What is segmentation?

Answer 35

Contraction of circular muscles that narrow small intestine's lumen to breakup chyme

Question 36

What are accessory organs?

Answer 36

Organs not a part of the GI tract that deposit enzymes into it e.g. pancreas, salivary glands, tongue, liver, gall bladder

Question 37

What is the pyloric sphincter?

Answer 37

Thick circular muscle at the base of stomach preventing digested food from going back into stomach from the small intestine.

Question 38

What is peristalsis?

Answer 38

Waves of muscular contractions that push food further down the alimentary canal. (successive bands of circular muscles contract in the oesophagus)

Question 39

What is the GI tract?

Answer 39

Gastrointestinal tract. The direct link between all organs

Question 40

What is the duodenum?

Answer 40

25cm long -first section of the small intestines, curving around the pancreas -most chemical digestion occurs here before chyme moves further along the intestine

Question 41

Functions of the lymphatic system

Answer 41

-return lymph fluid to the circulatory system -collect excess fluid (lymph) from tissue -absorb fats from digestive system -destroy infecting micro-organisms by phagocytic cells (phagocytosis-solid) -filter the lymph for foreign cells

Question 42

Function of a lymph node

Answer 42

Involved in the protection against infection

Question 43

What occurs due to a build of of fluid in tissue (lymph wise)?

Answer 43

-returned to blood by lymphatic system -lymph vessels are blind-ended tubes which means the system is a one way system carrying fluid away from tissue -lymph capillaries are larger than blood vessels which allows for easy passage of micro-organisms

Question 44

What is coeliac disease?

Answer 44

An intolerance to gluten -caused by inheritance -gluten is found in wheat, rye, barley -If gluten is eaten, their immune system responds by damaging or destroying villi in the small intestine -causing malnourishment

Question 45

What is bowl cancer?

Answer 45

-also called colorectal cancer -uncontrolled growth of cells in the large intestine's wall -a high red meat diet with low fruit may cause this