digestive system

Question 1

digestive system

Answer 1

Digestive system is the system that breaks down the food taken into the body ready for absorption into the cells.

Question 2

what do body cells need

Answer 2

simple sugars, amino acids, fatty acids, vitamins, minerals and water to function properly
Vitamins, minerals and water in the form of small molecules are able to pass through the differentially permeable membrane of the cell

Question 3

what is digestion

Answer 3

the process by which carbohydrates, proteins and fats are broken down into products small enough to be absorbed into the blood and to the cells. It is the mechanical and chemical breakdown of food to small molecules that can be absorbed into the body.

simple sugars, fatty acids and amino acids are eaten as complex carbohydrates, proteins and fats. These molecules are large and must be broken down into smaller units before being absorbed into the cells.

Question 4

what are the activities of digestion

Answer 4

Ingestion of food and water
Mechanical digestion of food
Chemical digestion of food
Movement of food along the alimentary canal
Absorption digested food and water into the blood and lymph
Elimination of material that is not absorbed

Question 5

mouth cavity

Answer 5

mechanical digestion by teeth

chemical digestion of starch by salivary glands

Question 6

pharynx

Answer 6

back of mouth cavity by moving up wards

throat that joins the mouth cavity to the oesophagus and larynx.

Question 7

mechanical digestion

Answer 7

mechanical breakdown of food into smaller particles

Question 8

chemical digestion

Answer 8

chemical breakdown of food into small molecules

Question 9

saliva

Answer 9

fluid that is secreted into the mouth cavity by 3 pairs of salivary glands to begin digestion. It contains a mucous and digestive enzyme, salivary amylase, which begins the chemical digestion of starch, breaks down large starch molecules into smaller molecules.

Question 10

how does ingestion occur in mouth

Answer 10

The action of jaw and teeth begins mechanical digestion, where food is broken into smaller products
Ingestion is the intake of food, liquids or drugs into the mouth.

Question 11

what are the teeth made of?

Answer 11

4 incisors - chisel shaped teeth that are used for biting or cutting, like taking a bite out of an apple
2 canines - one on each side of the incisors. Conical teeth used for tearing. Same length as the other teeth, carnivorous animals have longer canines for tearing
4 premolars - 2 on each side of the jaw
6 molars - 3 on each side of the jaw.

same number occurs at top

Question 12

oesophagus

Answer 12

tube 23-25cm that carries food from the throat (pharynx) to the stomach.

Question 13

what is the oesophagus made of?

Answer 13

double layer of muscles, longitudinal an circular muscle

Question 14

what is longitudinal muscle?

Answer 14

smooth muscle with fibres arranged lengthwise across an organ

Question 15

smooth muscle

Answer 15

smooth muscle with fibres arranged in a circle around the organ (alimetnary canal in this case)

Question 16

what is the stomach

what are the muscles of the stomach?

Answer 16

roughly j shaped enlarged section of the alimentary canal
mechanical digestion by churning action, waves of muscular contractions. chemical digestion by pepsin which begins protein digestion in infants, rennin coagulation milk protein.
contract in a variety of different ways to churn the food and mix it with the gastric juices, until food is converted into thick, soupy liquid called chyme.

longitudinal, oblique, circular.

Question 17

what is the pyloric sphincter

Answer 17

band of circular muscle that regulates follow of material from the stomach to duodenum.

Question 18

what is the pancreas

Answer 18

produces pancreatic juices containing enzymes for digesting proteins, lipids and nucleic acids.

Question 19

what is the small intestine

Answer 19

about 6m long after 2-8 hrs, contents of stomach moved to small intestine.
its lining secretes intestinal juice which contains many enzymes and the internal surface is lined with villi for absorption of digested food.

Question 20

what is the anus?

Answer 20

opening surrounding by the anal sphincter.

a muscle that can be voluntarily controlled.

Question 21

what is the salivary glands

Answer 21

3 pairs of glands produced saliva which dissolves food so it can be tasted. saliva contains mucous that lubricates mouth and food and holds food in the lump for swallowing. it also contains the enzyme salivary amylase, which begins the digestion of starch.

Question 22

what is the liver?

Answer 22

produces bile which is stored and concentrated in the gall bladder.
bile emulsifies lipids in the small intestine

Question 23

gall bladder

Answer 23

stores bile and releases it into the small intestine where the bile emulsifies lipids.

Question 24

duodenum?

Answer 24

first part of the small intestine

Question 25

what is the large intestine

Answer 25

has the transverse colon, ascending colon and descending colon largest part of the intestine absorbs water, minerals, vitamins.

Question 26

caecum

Answer 26

first part of the large intestine

Question 27

appendix

Answer 27

no function in human

Question 28

rectum?

Answer 28

final part of the large intestine in which faces are formed

Question 29

what is peristalsis

Answer 29

Peristalsis are waves of muscular contraction that push food along the alimentary canal. As the lump of food enters the pharynx and the oesophagus, the circular muscle behind it contracts to form a constriction. By contraction of successive bands of circular muscle, the constriction moves in a wave along the oesophagus, pushing the food in front of it. This wave of constriction is called peristalsis

Question 30

how is food moved along the alimentary canal?

Answer 30

As the lump of food enters the pharynx and the oesophagus, the circular muscle behind it contracts to form a constriction. By contraction of successive bands of circular muscle, the constriction moves in a wave along the oesophagus, pushing the food in front of it. This wave of constriction is called peristalsis Movement of food along the alimentary canal is lubricated by the secretion of mucous from the inner lining of the oesophagus

Question 31

what is the mucosa

Answer 31

The stomach lining (mucosa) is specialised for secretion of gastric juices. This contains hcl, mucus and digestive enzymes. Mucosa is a mucous membrane, the mucous membrane that forms the internal lining of the alimentary canal.

Question 32

what are gastric juices

Answer 32

Gastric juices are the digestive juices secreted by the gastric glands of the stomach.

Question 33

what are gastric glands

Answer 33

located in narrow tube like structures called gastric pits.

Question 34

why are nutrients not absorbed into the stomach

Answer 34

Nutrients are not absorbed into the blood through the stomach because the internal surface is covered by a thick layer of mucus. Some alcohol and other drugs like aspirin are absorbed in the stomach

Question 35

pyloric sphincter?

Answer 35

a ring of smooth muscle between the stomach and the duodenum. At the lower end of the stomach, there is a thickening of the circular muscle resulting in a constriction. chyme is pushed through peristalsis

Question 36

digestion the s. intestine

Answer 36

Digestion continues in the small intestine under the influence of intestinal juices secreted by glands in the lining of small intestine, pancreatic juices are secreted by the pancreas and bile secreted by the liver and stored in the gall bladder, released into the small intestine.

Question 37

how is the villus suited to its function

Answer 37

Each villus is about 1 mm long and is covered by a single layer of cells Inside the villus is a lymph capillary called a lacteal, which is surrounded by a network of blood capillaries Absorption is further enhanced by continual movement of the villi brought about by the muscular movements of the intestinal walls. This allows the villi to be in constant contact with different parts of the intestinal contents These contents are constantly changing as new material is emptying into the small intestine from the stomach

Question 38

how does absorption take place in the villus

Answer 38

tion: Some absorption occurs through simple diffusion as there is higher concentration of nutrient materials in the interior of the small intestine than in the cells lining the villi. Absorption also takes place in active transport, which involves the cells of the villi using energy to take in nutrients against a concentration gradient that is, taking in molecules from low to high concentration. From the walls of the villi, simple sugars, amino acids, water and water soluble substances are absorbed into the blood capillaries Fatty acids and glycerol recombine in th cells of the villi to form fats Substances that are absorbed into the blood capillaries, are carried by the hepatic portal vein to the liver In the liver they may be removed for further processing or remain in the blood to be carried to other body cells.

Question 39

what is the large intestine

Answer 39

The large intestine is about 1.5 m long and is larger in diameter than small intestine There are no villi There are no digestive juices secreted Lining secretes lots of mucus Movement through the large intestine is slow 18-24 hrs During this time, most of th e remaining water is absorbed, so contents are more solid. Bacteria in l.i. breaks down remming organic compounds Some bacteria produce vitamin which are aqfsored through walls into the blood. Mineral nutrients also absorbed Faeces are the semi solid components left after water absorption and bacterial action. They contain water and undigested food material cellulose, bacteria and bile pigments and the remains of cells that have broken away from the internal lining of the alimentary canal Defecation is not metabolic waste so not excretion it is elimination Elimination is the removal of indigestible material, bacteria and bile pigments from the body. The speed in which the material moves through the alimentary canal depends on its size and the contents of the meal A large meal causes greater stretching for the stomach and material is pushed more quickly into the small intestine than when the stomach is less distended High protein and high fat content in a meal slow the movement from the stomach to the small intestine Alcohol and caffeine stimulate movements of the stomach

Question 40

what is constipation

Answer 40

A condition in which defecation is difficult , with faeces being hard and dry Occurs if the movements of the large intestine are reduced and the contents remain there for a long period of time As water is absorbed, the faeces become drier and harder Defecation becomes difficult and painful May be caused by the lack of roughage (cellulose or insoluble fibre which is. a component of plant food) in the diet. Humans have no enzymes to digest cellulose, but is important as it stimulates movement in the alimentary canal May also be caused by lack of exercise or emotional problems.

Question 41

what is diarrhoea

Answer 41

Diarrhoea is the frequent defecation of watery faeces. Caused by the irritation of the small and large intestines, which increases peristalsis so that the contents of the intestines move through before threes adequate absorption of water This irritation is caused by a bacterial or viral infection (bacteria that produce food poisoning). Cholera bacteria causes severe diarrhoea that death results from dehydration through loss of water from the intestines.

Question 42

what is bowel cancer?

Answer 42

Bowl or Colorectal cancer is an uncontrolled growth of cells in the wall of the large intestine May be linked to diet, high alcohol consumption and smoking A diet high in red meat and processed meat and low in fibre (fruits and vegetables) may increase the risk of developing this. Risk factors involve being obese or overweight and physical inactivity.

Question 43

what is coeliac disease

Answer 43

People with this disease are unable to tolerate the protein gluten, which is found in wheat, rye and barley If gluten is consumed by people with this condition, their immune system responds by damaging or destroying the villi in the small intestine Without healthy villi, nutrients cannot be absorbed in the small intestine and the person becomes malnourished no matter how much food they eat. Symptoms vary from person to person and involve muscle cramps, joint pain, tingling in the legs. Some ppl may have no symptoms but are in full danger of being malnourished It is inherited No cure Only follow a diet with no gluten