The Digestive system

Question 1

Functions of the digestive system

Answer 1

1.Break down food into nutrients
2.Nutrients absorbed in the body
3. Transported through the circulatory system. Nutrients in the cell can be used as a source of energy or used for the synthesis of chemical compounds

Question 2

The 4 stages of digestion

Answer 2

1. Ingestion: taking in nutrients(eating/drinking)
2. Digestion: breaking down complex molecules into smaller ones
3. Absorption: Taking up of digestion molecules
4. Egestion: removal of waste

Question 3

Gastrointestinal tract(G1 tract)

Answer 3

the passageway or tube that extends from the mouth to the anus and in which the process of digestion takes place

Question 4

Mechanical(physical) digestion

Answer 4

-large pieces of food become smaller pieces, increasing the surface area
-Chewing of the food in the mouth
-Churning and mixing of food that occurs in the stomach

Question 5

Chemical digestion

Answer 5

-Parts of the digestive tract produce digestive enzymes
-Different enzymes break down macromolecules to small organic molecules that can be absorbed

Question 6

Physical and chemical digestion in the mouth

Answer 6

-Digestion starts in the mouth
-Food is broken down physically by the teeth and tongue
-The salivary glands release a substance called saliva
-Saliva contains a mixtures of water, mucus, and enzymes

Question 7

Amylase

Answer 7

enzyme found in saliva that breaks starch down to simple sugars

Question 8

Bolus

Answer 8

Food that has been chewed and mixed with saliva becomes a bolus

Question 9

How the body works with bolus

Answer 9

-As the bolus is pushed into the pharynx. the soft palate is raised to prevent food from entering the nasal passage
-A structure called the epiglottis also covers the entrance to the trachea so food does not enter our lungs but instead down the esophagus

Question 10

The esophagus

Answer 10

-The esophagus is a muscular tube that passes food from the pharynx to the stomach.
- Wave like muscle contractions called peristalsis move it towards the stomach.

Question 11

Stomach

Answer 11

-Mechanical and chemical digestion occur in the stomach
-The stomach is j-shaped, it stores food, and has a capacity of 2L

Question 12

Sphincters

Answer 12

-Food enters and exits the stomach through sphincters
-Sphincters are muscles surrounding a tube-like structure
-The bulus enters the stomach when the esophageal sphincters relaxes
-When the esophageal sphincter contracts, it prevents food from moving back into the esophagus

Question 13

Gastric juice

Answer 13

-The stomach releases gastrin which stimulates the release of gastric juice secreted by the cells in the stomach lining

Question 14

Gastric juice contains a mixture of

Answer 14

-HCI (hydrochloric acid): breaks down food fibres & bacteria
-Enzymes (pepsin)
-Mucus: Protect stomach lining from HCI
*im stomach lining is destroyed—> ulcers will form

Question 15

Cells of the stomach

Answer 15

-Parietal
-Cheif

Question 16

Parietal cells:

Answer 16

stomach cells found in the glands(secrete HCI)

Question 17

Cheif cells:

Answer 17

• Gastric cheif cells found in stomach produce pepsin, which breaks down large protiens into peptides(smaller protiens)
  -Replaced every 2-4 days

Question 18

Chyme

Answer 18

-Chyme travels out of the stomach by the pyloric sphincter into the small intestine
-Chyme is a mixture of: water, digested food, and gastric juices

Question 19

Stomach absorption

Answer 19

the stomach absorbs: water, alcohol, some medications(aspirin)

Question 20

Acid reflux

Answer 20

if the esophageal sphincter does not close completely, acid from the stomach enters the esophagus causing a burning sensation in the throat
-Called heartburn

Question 21

Stomach ulcers

Answer 21

-The acid found in the stomach can kill almost all bacteria except Helicobacter pylori
-This bacteria prevents mucus producing cells from making enough mucous to protect the stomach lining
-When the lining is exposed to the stomach acid, an ulcer can develop

Question 22

Small intestine

Answer 22

Three parts: duodenum, jejunum, Ileum
- Main function is to complete the digestion(chemically) of macromolecules and to absorb their component subunits
- After the pyloric sphincter, chyme enters the duodenum
-Duodenum is first 25cm of the small intestine

Question 23

Majority of digestion occurs in the..

Answer 23

Duodenum

Question 24

Secretions from pancreas and gall bladder enter the duodenum via a…

Answer 24

duct

Question 25

Pancreas and gall bladder secretes..

Answer 25

-maltose(carbs breakdown) -Peptidase(protein breakdown)

Question 26

Absorption in the small intestine:

Answer 26

-Most absorption takes place in the Jejunum and Ileum -After the duodenum, the jejunum and ileum contain villi which increase the surface area

Question 27

villi

Answer 27

-Villi help absorb glucose, amino acids, fatty acids, glycerol -Each villus has a small lymphatic vessel called a lacteal and a network of blood capillaries surrounded by a layer of epithelial cells -Microvilli extend into the intestinal lumen to create a “brush border” -Nutrients are absorbed across the epithelium and then across the unicellular wall of the capillaries or lacteals -Nutrients then enter bloodstream and are dispersed throughout the body

Question 28

Liver

Answer 28

-Has 4 functions: Synthesis, breakdown, detoxification, storage -Synthesis: produces bile which breaks down fats. bile is stored in the gall bladder -Detoxification: Removes toxins from the body including alcohol and chemicals -Storage: Vitamins and carbs(such as glycogen) are stored in the liver

Question 29

Pancreas

Answer 29

-Increase the PH of chyme from 2.5 to 9 due to the production of sodium bicarbonate which is an alkaline(base) -Secretes enzymes for digestion - Carbs-breaks down carbs - Lipase-(breaks down fats) - Trypsin(breaks down protiens)

Question 30

Large intestine

Answer 30

-Water, sodium, chlorine are absorbed -Bacteria living in colon releasing vitamin k and b also absorbed

Question 31

Egestion

Answer 31

-Egestion is the removal of the indigestible components of food(cellulose/fibre) -The rectum stores and compacts waste -Cellulose(found in plant cell walls) aids in the ejection of material from the bowels. It’s the main source of our dietary fibre -Lack of cellulose in the diet can increase the risk of colon cancer