2.3 - The digestive organs

• Biologie
• Middelbare school
• havo
• Leerjaar 2

2.3 - The diestive organs

Today's lesson

 HW review

 The digestive organs

HW review

Q8 - food list

Pick a partner and answer the following questions:

1. What food products did you both eat?

2. What proucts did you both drink?

3. What did your partner eat that you would NEVER eat.

4. Look at your products. Choose 3 that you both ate. Which nutrients are in each of these products?

Oral cavity, pharynx and oesophagus

-digestion begins in oral cavity

-chewing breaks food into small

pieces 

-salivary glands make saliva

-saliva has water, mucus, and enzyme

-Enzyme in saliva breaks down starch

-Swallowing: Food via pharynx to 

oesophagus - uvula and epiglottis closed

-Peristalsis moves food to stomach

Why is your stomach rumbling? 

-peristalsis

-muscle activity 

- circular and longitudinal muscles

- mechanical digestion

-stomach constantly moving

-Empty stomach and intestines make a louder sound!

In your stomach

Digestive juices are added

-pyloric sphincter

-temporary storage area

-Gastric glands make gastric juices

-Gastric juices are made up of water, hydrochloric acid and enzyme

-Hydrochloric acid kills bacteria

-Gastric juices start to digest proteins

Duodenum, Liver, Gall Bladder and Pancreas

2 important liquids added in the first part (the duodenum)

• Bile made in the liver, stored in the gall bladder
• Bile emulsifies fats, NO digestion - increases surface area of fats for enzymes to act upon
• Pancreas makes pancreatic juices - different enzymes to digest proteins, carbohydrates and fats

small intestine 

• is very long-> 6 meters
• contains intestinal glands that make intestinal juice
• Intestinal juice digests proteins and carbohydrates
• has many fingerlike projections-> Villi
• Large total surface area -> making  absorption go faster

Characteristics of villi

• One cell layer thick (thin walls for faster absorption)
• Good blood supply (fast transport of nutrients to the rest of the body)

Appendix

It has no function but can become infected and has to be removed.

Large intestine

• About one and a half meters long
• Mainly fibre, dead cells, bacteria and water
• Water absorbed in the blood 
• No all food can be digested - cellulose from cell walls (plants)
• waste product becomes more solid-> faeces

Where does faeces collect?

• in the RECTUM
• when enough is collected the brain signals for elimination
• Anus - a sphicter (circular muscle) relaxes and rectum empties
• this is called a bowel movement