Digestion and Absorption

Question 1

Thecodont

Answer 1

Teeth are embedded in the jaw

Question 2

Heterodont

Answer 2

Different teeth for different functions 
Incisors- cutting food
Canines- cutting and tearing food
Premolars- crushing food
Molars- grinding food

Question 3

Diphydont

Answer 3

Two sets of teeth in a lifetime-
milk teeth
permanent teeth

Question 4

Dental formula in an adult human

Answer 4

2123/2123

Question 5

Rugae

Answer 5

The mucous membrane of the stomach is thrown into numerous longitudinal folds called rugae when the stomach is empty.

Question 6

Composition of saliva

Answer 6

It contains 99.5% water
It contains two enzymes:
> Salivary amylase
> Lysozyme

Question 7

First step in the digestion of food

Answer 7

Salivary amylase action

Question 8

Function of salivary amylase

Answer 8

Breaks down starch in food into simple sugars

Question 9

Function of lysozyme

Answer 9

Lysozyme destroys the bacteria that enter along with the food
OR
causes lysis of several common bacteria that may be present in the mouth

Question 10

Function of mucin

Answer 10

Helps in the lubrication of food for swallowing

Question 11

Gastric glands + their functions

Answer 11

1. Fundic glands (Oxyntic glands)- secrete HCl, pepsinogen, soluble mucin (ACIDIC)
2. Pyloric glands- secrete mucin but no HCl (ALKALINE). Also secretes the hormone gastrin
3. Cardiac glands- secrete mucin, pepsinogen (ALKALINE)

Question 12

Why is gastric chyme acidic in nature?

Answer 12

Gastric chyme is acidic in nature because of the presence of HCl

Question 13

Functions of HCl (Functions of gastric juice)

Answer 13

+ Converts pepsinogen —> pepsin

+ Kills the bacteria in food

Question 14

Functions of pepsin (Functions of gastric juices)

Answer 14

Breaks down the proteins in food into peptones and polypeptides.
This stimulates the secretion of gastro-intestinal hormones in the small intestine

Question 15

Functions of mucus (Functions of gastric juices)

Answer 15

Protects the gastric mucosa from the acidic pepsin.
Lubrication of food in the stomach
Retains water as the aqueous environment facilitates digestion in stomach.

Question 16

Functions of liver

Answer 16

• Acts as an exocrine gland with the secretion of bile.
• Metabolism of carbohydrates, proteins and fats.
• Regulation of blood glucose and lipids.
• Storehouse of vitamins, glycogen and iron.
• Detoxification of drugs and alcohol.
• Removal of unwanted particulate matter from blood through the mediation of macrophages.

Question 17

Functions of bile

Answer 17

• Emulsification of fats.
  
  • Helps to keep the cholesterol in solution.
  • Mild purgative action.

Question 18

Functions of pancreas

Answer 18

• Pancreas has both exocrine and endocrine part.
• Exocrine part secretes enzymes that play an important role in digestion of proteins, carbohydrates and fats.
• Endocrine part (Islets of Langerhans) consists of three types of cells.
→ Alpha cells- secretes the hormone glucagon.
→ Beta cells- secretes the hormone insulin.
→ Delta cells- produces the hormones gastrin and somatostatin.

Question 19

Process of ingestion

Answer 19

• It is a process that takes place in the mouth (buccal cavity).
• Food is taken in the buccal cavity, cut and chewed by the teeth.
• The saliva mixes with the food, lubricating it.
• The salivary amylase breaks the starch into maltose.
• The masticated food is now called a BOLUS
• From the pharynx, the bolus is swallowed and the process is called DEGLUTITION.
• The food that travels along the oesophagus, reaches the stomach by muscular
contractions of the food pipe (oesophagus) called PERISTALSIS.

Question 20

Digestion of carbohydrates

Answer 20

1. BUCCAL CAVITY
   Salivary Amylase (pH 6.8)
   Starch –> Maltose
   (3-5%) Parotid glands

2. STOMACH 
There is no carbohydrate digesting enzyme in the stomach 
             HCl
Starch  ----->   Maltose
(30-40%) 

3. INTESTINE (Duodenum) 
Acidic chyme mixes with bile (not enzyme), pancreatic juices, intestinal juices 
             Pancreatic amylase (pH 8.8) 
Starch  ----------------------------------------> Maltose
(50%)                Duodenum 

4. INTESTINE (Small Intestine) 
               Maltase 
Maltose -------------> 2 Glucose
                 Sucrase 
Sucrose -----------------> 1 Glucose
               Dextrinase
Dextrin -------------------> 1 Glucose
              Lactase 
Lactose ----------> 1 Glucose + 1 Galactose

Question 21

Digestion of proteins

Answer 21

1. STOMACH
   HCI (pH 1-2)
   Pepsinogen ————-> Pepsin
   Pepsin
   Protein ————> Proteoses / Peptones
   Pepsin
   Casein —————> Paracasein (milk coagulation)
   Rennin (Seen in infants and absent in adults; rennin is more effective than
   casein because infants only drink milk)
2. SMALL INTESTINE (Upper small intestine)- Pancreatic peptidases

                                 Enterokinase  Inactive trypsinogen --------------------> Trypsin 
   
            Trypsin Proteins ---------------> polypeptides 
   
                       Carboxypeptidase  Polypeptides  ------------------------------> Simple peptides 
   
          Chymotrypsin  Casein ----------------------> Paracasein

3. SMALL INTESTINE (Intestinal juices)
   aminopeptidases
   Peptides ————————> Aminoacids

Question 22

Digestion of fats

Answer 22

All fat digestion takes place in the small intestine.
Bile
Fat —————> Emulsified fat

                        pancreatic lipase  Emulsified fat -----------------------------> Fatty acids, Glycerol, 2 monoglycerides

Question 23

Why doesn’t protein digestion take place in the buccal cavity?

Answer 23

Saliva has no proteolytic enzyme, so no protein digestion takes place in the buccal cavity.

Question 24

Absorption

Answer 24

> Carbohydrates —> Monosaccharides (Glucose) —> absorbed by the blood stream

                                blood > Monosaccharides ------------> Glycogen (Liver)  > Proteins ---> amino acids ---> absorbed by blood stream     Amino acids ---> Energy (tissues) for metabolic activities  > Fats ---> Fatty acids, glycerol ---> duodenum and jejunum    Fats are incorporated into water soluble droplets called Micelles and then absorbed

Question 25

Egestion

Answer 25

Unwanted food is eliminated from the body by a process called DEFAECATION

Question 26

Mechanism of absorption

Answer 26

> Passive transport- Diffusion and osmosis > Active transport

Question 27

Calorific values of i) proteins ii) fats iii) carbohydrates

Answer 27

i) proteins- 5.65 kcal ii) fats- 9.45 kcal iii) carbohydrates- 4.1 kcal

Question 28

Constipation: definition + causes + symptoms + treatment

Answer 28

Defintion: Infrequent or difficult defaecation which causes discomfort is known as constipation. ``` Causes: > improper bowel habits > colon spasms > insufficient fibre intake > inadequate fluid intake ``` Symptoms: > difficult or infrequent passing of motions Treatment: > Use of mild laxative that induce defaecation > Eating fibrous foods like apples, bananas, drumstick, snake gourd

Question 29

Emesis/vomiting: definition + process

Answer 29

Definition: Emesis is a condition when contents of the stomach come out through the oesophagus into the mouth and out of it. It could be cause by nausea, constipation or changes in the body's equilibrium due to motion. Irritation in the stomach causes the abdominal muscles to contract leading to emesis/vomiting.

Question 30

Diarrhoea: definition + causes + symptoms

Answer 30

Definition: Frequent and profuse defaecation of liquid faeces is called diarrhoea. Causes: Increased motility and decreased absorption by the intestines. Lactose intolerance, stress, microbes irritating gastrointestinal mucosa. Symptoms: Liquid faeces Continuous abdominal pain, bleeding from the rectum

Question 31

Jaundice + characteristics + 3 types

Answer 31

It is a symptom that always indicates serious disease. Characterised by: i) yellow pigmentation of the skin and sclera of the eye due to bilirubin ii) excess bilirubin concentration in the blood 3 types: 1. prehepatic jaundice 2. hepatic jaundice 3. extrehepatic jaundice

Question 32

Prehepatic jaundice: cause + characteristics

Answer 32

Medically known as haemolysis > Caused due to excess production of bilirubin. > It is a neonatal disease i.e. seen in small babies, usually 3 to 5 days after their birth > If it doesn't go away, the baby is kept in an incubator that provides light in the NICU > In abnormal conditions, can also be caused by sickle cell anaemia, rhesus incompatibility, thalassaemia major

Question 33

Hepatic jaundice: causes

Answer 33

Due to congenital liver diseases, liver cirrhosis (in an alcoholic), or hepatitis Infections are usually responsible for this kind of jaundice

Question 34

Extrahepatic jaundice

Answer 34

> occurs outside the liver, not inside > when the cystic duct or the bile duct gets blocked > blockage of bile drainage by gallstones > bowel cancer, pancreatic cancer or liver cancer

Question 35

PEM- full form + two main disorders

Answer 35

Protein energy malnutrition two main disorders: 1. Kwashiorkor 2. Marasmus

Question 36

Kwashiorkor

Answer 36

``` > wet protein energy malnutrition > protein deficiency > age - from 6 months > fluid retention (edema) > dry, peeling skin > extremely thin extremities/legs and arms ```

Question 37

Dysentery

Answer 37

A different form of diarrhoea as it is caused by a protozoan or bacterial infection and streaks of blood, mucus are seen in the faeces

Question 38

Indigestion

Answer 38

Any minor discomfort coming on after meals is called indigestion It causes a feeling of fullness, heart burn, regurgitation of water (water brash), bloated stomach