The Digestive System

Question 1

1- list the four main functions of the digestive tract

Answer 1

-Break down (physically and chemically)
Makes it small
Absorbed through gut wall into blood
Utilisation of energy and nutrients
Gets rid of things we don’t need

-Absorbs water
-Excrete cholesterol
-Synthesise vitamins

Question 2

2- how many of the GI tract organs can you name, in order from mouth to anus?

Answer 2

Mouth
Oesophagus
Stomach
Pancreas
Duodenum (of small intestine)
Jejunum (of small intestine)
Ileum (of small intestine)
Cecum (of large intestine)
Large intestine
Anus

Question 3

2- functions of the mouth

Answer 3

Physical food breakdown
Digestive enzymes released
Infection control

Question 4

2- functions of the oesophagus

Answer 4

Rapid transport of bolus (food that has been chewed and mixed in the mouth with saliva) to stomach via thorax

Question 5

2- name the main salivary glands, what are the functions of saliva?

Answer 5

Parotid
Submandibular
Sub-lingual

Functions of saliva:
Digestive enzyme release
Oral hygiene
Lubricate bolus for transport down oesophagus

Question 6

2- main functions of the stomach

Answer 6

Storage
Produce chyme- the stuff that leaves the stomach (physical and chemical breakdown)
Produce acid (untangles protein, activates enzymes and disinfects)

Question 7

2- functions of the duodenum

Answer 7

Is the start of the small intestine
Pancreas and liver join gut tube here

Neutralises chyme (which is acidic)
Water enters walls to dilute the chyme
Digestive enzymes enter

Question 8

3- list the main functions of the liver

Answer 8

Composed of hepatocyte cells
Bile production
Protein synthesis
Detoxifies blood
Energy storage (glycogen)

Question 9

4- describe the functions of a liver cell (refer to bile secretion, and metabolism of carbohydrates, proteins and lipids)

Answer 9

About 60% of the liver is made up of liver cells called hepatocytes (HCs), there are over 200,000 in every mg of liver tissue!
There are 3 other cell types too: HSCs, KCs, LSECs

Bile secretion:
-green/yellowish fluid
-consists of waste products, chemicals and bile salts
-secreted by liver cells to perform two major functions
1- carry away waste (in the form of faeces) 2-break down fats during digestion (bile salt job)

Metabolism:
Carbohydrates-
Excess glucose after a meal= GLYCOGENESIS
Later decline of glucose= GLYCOGENOLYSIS
Proteins-
Examination and transmission of amino acids
Ammonia removal via urea
Non-essential amino acid synthesis
Plasma protein synthesis
Fats-
Oxidisation of triglycerides for energy
Excess carbs converted into fatty acids for storage in tissue
Cholesterol synthesis

Question 10

5- outline the structure and function of the gallbladder

Answer 10

Connected above to liver
Connected below to duodenum

Stores and concentrates bile from the liver
System of Hillary tubes connect it to the rest of the GIT
When fat is detected in the duodenum it contracts and releases bile into the duodenum

Question 11

6- what are the constituents of bile?

Answer 11

Bile salts
Cholesterol
Bilirubin

Question 12

6- what are the functions of bile?

Answer 12

Bile salts
Emulsify fats into smaller droplets

Cholesterol
Bile helps to excrete excess cholesterol from the body (fat in blood)

Bilirubin
This substance is released when RBCs die
Gives poo brown colour
If not excreted= jaundice

Question 13

2- structure and functions of the pancreas

Answer 13

Endocrine (small bit of pancreas)
Insulin and glucagon production

Exocrine (most of pancreas)
Enzyme production for digestion

Question 14

2- structure and functions of the jejunum/ileum

Answer 14

Final stage of digestion
Absorbs nutrients
Absorbs electrolytes and water

Question 15

2- structure and function of the large bowel

Answer 15

Final absorption of water
Temporary storage

Question 16

2- structure and function of the anus

Answer 16

Defecation

Question 17

7- structure of carbohydrates in the body

Answer 17

Long chains of sugars (starch)- rice, potatoes, bread
Shorter chains of sugars (starch)- lactose in milk
Single sugar unit is a monosaccharide

Question 18

7- function of carbohydrates in the body

Answer 18

Carbohydrates to sugars

Body’s primary source of energy
Brains preferred source of energy
Body breaks them down into glucose using enzymes
Glucose= fuel by organs, cells and tissues
Only monosaccharide can be absorbed (single sugar unit)

Question 19

7- structure of proteins in the body

Answer 19

Long chains of amino acids (polypeptides)
Pepsin= the enzyme in the stomach that digests proteins
Amino acid chains are held together by peptide bonds

Question 20

7- function of proteins in the body

Answer 20

Proteins to amino acids

Helps body to repair cells and make new ones
Important for growth and development in babies, children and teens

Chains broken down by protease enzymes like pepsin

Protease enzymes break down protein, but the gut is also made of protein! To stop protease digesting it’s own gut, the enzymes are only activated when in safe environment. Otherwise, they are stored as an inactive form

Question 21

7- structure of fats in the body

Answer 21

Individual molecules called fatty acids
Make up chains of carbon and hydrogen atoms, linked by single or double bonds
Fatty acid chains vary in length

Question 22

7- function of fats in the body

Answer 22

Fat to fatty acids to monoglycerides

Energy storage
Insulation from the cold
Lubrication of bodily surfaces
Carries fat-solvable vitamins
Make up cell membranes

Bile and enzymes (lipases) digest fat