Digestive System

Question 1

What is the difference between mechanical digestion and chemical digestion

Answer 1

Mechanical: food down from large to small pieces this increase the surface area makes it easier to chemically digest

Chemical: with aid of enzymes large food molecules are chemically broken down into smaller units to be absorbed by the body (enzymes are a biological catalyst)

Occur in the mouth stomach and small intestine

Question 2

Define incisors,canine premolars and molars

Answer 2

Incisors: (4) chisel shaped teeth used for biting cutting as when you’re taking a bite of an apple

Canines: (Two) one on each side of the incisors these are conical teeth used for tearing human canines are the same length as the other teeth

Pre-molars: (two) two on each side of the jaw

Molars: (Six) the pre-molars and molars have broad crowns with the rounded cups for cups of This makes pre-molars and molars ideal for crushing and grinding food

Question 3

explain chemical digestion in the mouth

Answer 3

as the food is chewed it is mixed with the saliva a fluid which is secreted into the
mouth cavity by the parotid gland, submandibular glad and the sublingual gland the salivary analyze (degrades starch) , lingual lipase (digests lipids) , and lysosomes (kill bacteria0

Question 4

explain mechanical digestion in the mouth

Answer 4

the teeth and the tongue increase the accessibility to enzymes and the tounge shapes the food in a bolus saliva softens the food the tounge moves it upwards and backwards pushing the bolus to the back of the mouth

Question 5

what digestion occurs in the esophagus

Answer 5

the esophagus is made up off circular muscle fibers arranged in a circular pattern and longitudinal muscle which allow for peristalsis to occur which is a wave of muscle contraction after the esophagus the bolus will pass through the cardiac spinster which allows for food to enter the stomach and prevents food from leaving the stomach and prevents ingestion and heart burn.

Question 6

how is mechanical digestion achieved in the stomach

Answer 6

by waves of muscular contraction that move along the stomach wall this mixes and churns the food being digested it mixes with gastric juice until it produces cyme

Question 7

how is chemical digestion achieved by the stomach

Answer 7

gastric juice’s play a large role in this it contains hydrochloric acid mucos and enzymes pepsin and gastric lipase gastric juice’s begin protein digestion pepsin breaks down proteins down into smaller peptides

Question 8

What is faeces elimination rather than excretion

Answer 8

Because excretion is removal of metabolic waste and faeses arent the elimination of metabolic wastes so it is referred to as elimination

Question 9

what are the 6 basic functions of the digestive system

Answer 9

1 ingestion of food and water
2 mechanical digestion of food
3 chemical digestion of food
4 movement of food along the alimentary canal
5 absorption of of food and water into the blood and lymph
6 elimination of material that is not absorbed

Question 10

what does salivary amylase, lingual lipase, lysosomes, gastric protases (pepsin), gastric lipase, pancreatic amylase, pancreatic protease, pancreatic lipase and deoxyribonuclease and ribonuclease chemically digest

Answer 10

Salivary amylase degrades starch to simpler disaccharides.

Lingual lipase begins to digest lipids (produced by glands on the tongue)

Lysozyme- enzymes which kill bacteria

gastric protases or pepsin breaks down amino acids which make up proteins are broken down into chains called polypeptides and kills bacteria

gastric lipase: is an enzyme that breaks down dietary fats into smaller molecules called fatty acids and glycerol

pancreatic amylase: breaks down starch into disaccharides

pancreatic protease (trypsin) breaks proteins into peptides

ribonuclease and deoxyribonuclease digests DNA and RNA

Question 11

identify the roles of the intestinal juice’s produced by the small intestine

Answer 11

intestinal amylase breaks down disaccharides into simple sugars

intestinal peptidases breaks down polypeptides into amino acids

intestinal lipase breaks down lipids into fatty acid and glycerol

Question 12

where is bile secreted and what is its function

Answer 12

bile is produced by the liver and stored in the gall bladder bile is secreted into the small intestine the common bile duct but it does not contain any enzymes bile salts are very important as they act as a detergent and emulsify the fat breaking it down into small droplets this is mechanical digestion as it increases the surface area on which the lipases can break them down.

Question 13

why is the small intestine so effective in absorbing nutrients

Answer 13

because the surface area of the small intestine has many folds and the surface area of the small intestine is very large and on the surface of the small intestine there are many microscopic villi and micro villi.

Question 14

how are fatty acid amino acids simple sugars and water soluble vitamins absorbed by the villi

Answer 14

fatty acid are absorbed through simple diffusion in the cell off the villi

amino acid is absorbed by active transport into the blood capillaries

simple sugars are absorbed through active transport and the cells of the villi and into the blood capillaries

water soluble vitamins travel through diffusion to the blood capillaries

Question 15

What is the dental formula

Answer 15

2-1-2-3

Question 16

Absorption of nutrients is essential to sustain life. Outline how the three major nutrient groups and water are absorbed from the small intestine into the body

Answer 16

Carbohydrates:
Digested in the small intestine by pancreatic juice and intestinal juice. Specifically pancreatic amylase (1 mark)
Pancreatic amylase breaks down starch into disaccharides (1 mark) and intestinal juice contains amylases to break down disaccharides to simple sugars (1 mark)

Proteins:
Digested in the small intestine by pancreatic juice and intestinal juice. Specifically pancreatic protease (1 mark)
Pancreatic protease breaks down proteins and polypeptides into peptides (1 mark) and intestinal, containing peptidases, breaks down peptides to amino acids (1 mark)

Lipids:
Digested in the small intestine by pancreatic juice and intestinal juice. Specifically by pancreatic lipases (1 mark)
Pancreatic lipases breaks lipids into fatty acids and glycerol (1 mark) and intestinal juice contains lipases to break down lipids to fatty acids and glycerol (1 mark)

Water:
Water is absorbed through the wall of the small intestine with the products of digestion into the blood/water is absorbed through the intestinal wall via diffusion (1 mark)