Digestive System

Question 1

What is Digestion?

Answer 1

Digestion is the process of breakdown of large complex molecules which are insoluble into simple molecules which are soluble in our body. The breakdown of these molecules is down by a chemical substance called Enzyme.

Question 2

What are enzymes and 5 characteristics?

Answer 2

Enzymes are biological catalysts which enhance the rate of reaction.
1. it is a protein and therefore it is destroyed by heating.
2. It acts on only 1 kind of substance called the substrate.
3. It can be used several times.
4. It acts best at a particular pH
5. It always forms the same end products from the substrate.

Question 3

Dental Formula for a child, adolescent and an adult?

Answer 3

Child - 2,1,0,2, / 2,1,0,2 = 20 milk teeth

adolescent - 2,1,2,2 / 2,1,2,2 = 28 permanent teeth

adult - 2,1,2,3 / 2,1,2,3 = 32 permanent teeth including 4 wisdom teeth.

Question 4

Define Dentition.

Answer 4

Dentition is the arrangement of various types of teeth depending upon the food habits of an organism.

Question 5

When do wisdom teeth grow?

Answer 5

17-20 years.

Question 6

Describe the structure of a tooth.

Answer 6

Crown - the part exposed above the gum. It consists of the Enamel (covers the crown n is the hardest substance) and Dentine (forms bulk of the tooth and it is harder than bone but not enamel.)

Neck - slight constriction b/w crown and root.
Root - Cementum is a bone like structure covering the root and fixing it in position. The pulp is a soft connective tissue in the central space of the tooth. PULP = BLOOD CAPILLARIES, LYMPH VESSELS, NERVE FIBRES.

Question 7

Name three salivary glands.

Answer 7

Parotid Gland - in front of each ear
Sub-mandibular Gland - each side of lower jaw
Sub-lingual Gland - below tongue

Question 8

Enzyme produced in the mouth is called?

Answer 8

Ptyalin or salivary amylase.

Question 9

The enzyme ptyalin converts what into what?

Answer 9

Starch —-> Maltose

Question 10

Explain swallowing.

Answer 10

The tongue moves up and presses against the palate therefore pushing the food into the Esophagus.

Question 11

What does the Epiglottis do?

Answer 11

The epiglottis which is present near the trachea prevents the entry of bolus into the trachea by acting like a flap and closing it.

Question 12

What is Peristalsis?

Answer 12

It is the rhythmic wave of constrictions in the circular muscles of the gut which helps in pushing the food forward to the next part of the alimentary canal.

Question 13

Stomach?

Answer 13

Elastic Bag located right below the Diaphragm. Protein digestion takes place here. The inner lining of the stomach secretes Gastric Juice.

Question 14

What is pylorus?

Answer 14

It is the opening of the stomach into the small intestine.

Cardiac Sphincter is at the front end of the stomach to prevent black flow of food into esophagus.

Question 15

What is Antiperistalsis?

Answer 15

Is when the cardiac sphincter opens and a reverse wave of muscular contraction is caused throwing food out of the mouth. It is also known as vomiting.

Question 16

Gastric Juice has which enzyme? And what does it do

Answer 16

It activates pepsinogen to act on proteins. Pepsin digests proteins into peptides.

Question 17

Which enzyme converts casein into paracasein?

Answer 17

Rennin

Question 18

Regions of the Small Intestine?

Answer 18

Duodenum - Most of the digestion occurs here. 12 finger widths in length. Bile is secreted from the liver and transported through the bile duct into the duodenum. Panc juice is secreted by the pancreas and transported into the duodenum through the pancreatic duct.

Jejunum - It is always empty after death.

Ileum - Contains many enzymes. 4m long. Inner lining of the ileum is thrown into folds called villi which help in absorption.

Question 19

What are the enzymes in Ileum? Enzymes in the intestinal juice?

Answer 19

Erepsin converts peptides into amino acids
Maltase - digests maltose into glucose.
Sucrase - splits sucrose into glucose and fructose.
Lactase - digests lactose into glucose and galactose.
Lipase - digests fats into fatty acids and glycerol.

Question 20

Structure of villi and what are villi?

Answer 20

Villi are finger-like projections in the inner lining of ileum. They increase the surface area of the intestine which helps in the absorption of food. Between the villi there are small holes which secrete intestinal juice.

Epithelium - absorbs glucose and amino acids.
Capillaries
Lacteal - absorbs fatty acids and glycerol
Vein
Artery
Hepatic portal vein - absorbs amino acids, fructose, glucose and transports them to the liver.
Lymphatic duct

Question 21

What are the adaptions of ileum for the absorption of food?

Answer 21

It is very long.
Villi increase the surface area for absorption.
Single-celled epithelium.
It is narrow which slows the movement of food, allowing absorption.

Question 22

What is bile?

Answer 22

Bile is a yellowish-green fluid secreted by the liver and is transported to the small intestine through the hepatic duct.
The bile gets its yellowish-green color due to pigments such as bilirubin and biliverdin.
Bile helps convert acidic chyme to basic and does the emulsification of fats.

Question 23

What is emulsification?

Answer 23

Emulsification is the breakdown of fats by the bile into tiny droplets for providing greater surface area for the action of enzymes.

Question 24

Pancreatic Juice? Enzymes in this juice?

Answer 24

It is produced in the Pancreas located behind the stomach.

Amylopsin - digests starch into maltose

Trypsin - converts proteins and polypeptides into smaller peptides and amino acids

Steapsin - acts on emulsified fats to split them into fatty acids and glycerol.

Question 25

3 parts of the Large Intestine? LARGE INTESTINE = 1.5 METERs LONG WHERE AS SMALL INTESTINE = 7 METERs LONG.

Answer 25

Caecum - located at junction of small and large intestine. It contains the appendix which is a functionless organ.

Colon - more than 1m long and thicker than ileum. The colon absorbs excess water.

Rectum - 15 cm long and opens at the anus. It temporarily stores faeces .

Question 26

Functions of large intestine?

Answer 26

It absorbs much water but little digested food from the contents which consist of undigested material.

Question 27

Define defecation.

Answer 27

Is the expulsion of undigested remains of the food from the alimentary canal.

Question 28

FAECES = 75% WATER
25% SOLID MATTER WHICH HAS

30% ROUGHAGE AND 30% DEAD BACTERIA

10-20% FAT
2-3% PROTEINS

Answer 28

nothing

Question 29

ASSIMILATION OF FOOD?

Answer 29

Is the conversion of absorbed digested material into body material.

Question 30

BREAKDOWN OF GLUCOSE THRU CELLULAR RESP GIVES ENERGY TO BODY

Question 31

Excess glucose is stored in liver as what?

Answer 31

Glycogen - Glycogenesis

Question 32

Process of glycogen being reconverted into glucose?

Answer 32

Glycogenolysis

Question 33

Amino acids?

Answer 33

are the building blocks of protein and they cannot be stored.

Question 34

Deamination?

Answer 34

is the break down of excess amino acids into urea for excretion.

Question 35

Function of lacteal?

Answer 35

Is to absorb fatty acids and glycerol and to transport them to the lymphatic system.

Question 36

Fatty acids and glycerol?

Answer 36

They are used in the synthesis of certain compounds in the body cells.

Question 37

Excess fat is stored below the skin as what?

Answer 37

Sub-cutaneous fat

Question 38

Liver functions

Answer 38

Is the largest gland and it weighs about 1.5 kg. Reddish-brown located on the upper-right side of abdomen below the diaphragm.
Produces bile.
Helps in emulsification of fats.

Destroys dead red blood cells,
controls blood sugar levels,
stores iron/copper and vitamins,
controls amino acid levels,
Produces heat by cellular metabolism.