13. The digestive system

What is the function of the digestive system?

• To break down food, a

• bsorb nutrients,

• and eliminate waste.

What are the two types of digestion in the mouth?

ex?

What are the two types of digestion in the mouth?
1. Mechanical

• (chewing)

2. chemical

• (saliva enzymes).

enzymes do what?

enzymes

• break down the food into nutrients

• After teeth cut, tear, grind & crush the food,

What is peristalsis?

• Rhythmic muscle contractions that move food through the digestive tract in esophagus

What is the pH of the stomach?

• 2–4 (acidic).

What enzyme digests protein in the stomach?

• Pepsin.

• HCi

What is chyme?

• A mixture of food and stomach acid.

Where does most digestion and absorption occur?

• Small intestine.

What is the first part of the small intestine?

• Duodenum.

What structures increase surface area for absorption in small intestine?

• Villi

• microvilli.

What enzyme digests protein in the small intestine?

• Trypsin.

What enzyme digests fats in stomach and small intestine?

• Lipase.

What enzymes digest carbohydrates in the small intestine?

• Maltase,

• sucrase,

• lactase.

What is the function of bile in the liver and gallbladder?

• Emulsifies fats

• breaks them into smaller droplets

Q: What happens if bile is blocked?

• Jaundice (yellow skin).

Large Intestine

Q: What is the function of the large intestine?

Large Intestine

• Absorbs water and minerals;

• forms feces.

Q: What causes diarrhea?

• Low water absorption in large intestine

Q: What causes constipation?

• High water absorption in large intestine.

Put the main digestives system parts in order:

Mouth → Esophagus → Stomach → Small intestine → Large intestine → Rectum → Anus

What enzymes digests carbohydrates in the mouth

• Amylase → in saliva

– digests carbohydrates in the mouth

Mouth pH = 7 (neutral)

Mouth pH = 7 (neutral)

3)Intestine – pH 8-9

→ Basic

3)Intestine – pH 8-9

→ Basic

the epiglottis: ?

he epiglottis:

• Is a flap

• Stops food from going into lungs

ESOPHAGUS

The esophagus is?

how it works?

Food moves down esophagus due to?

The epiglottis:

?

ESOPHAGUS

• The esophagus is a food tube.

• After you swallow,

• food moves past the pharynx & the epiglottis (flap)

• to the muscular tube that links the mouth & stomach, called the esophagus.

Food moves by:
👉 Peristalsis =

• rhythmic, muscular contractions of the smooth muscle that lines the esophagus.

The epiglottis:

• Is a flap

• Stops food from going into lungs

STOMACH

The stomach:

• Uses

• enzymes that works here: ?

• The mixture of broken-down food and stomach acids is called (Food + acid) = ?

• The stomach has?

• Too much acid → ?

STOMACH

The stomach:

• Is a muscular organ/bag

• uses muscles and acids

  to churn (stir) the food

• Churns food (mechanical digestion)

• Uses acid & enzymes (chemical digestion)

What works here:

• HCl → helps digest protein & kills bacteria

• Pepsin → digests protein

• Lipase → digests fats

The mixture of broken-down

food and stomach acids is

called (Food + acid) =

• CHYME
  (it looks like green pea soup 🤢)

The stomach:

• Has sphincters to prevent stomach acid from getting into esophagus or small intestine

• Is lined with mucus so it doesn’t digest itself

Too much acid

• Excessive acid corrodes the stomach wall and makes holes that are very painful

• → ulcers

SMALL INTESTINE + Pancrea (MOST IMPORTANT)

• This is where: ?

• length?

• diameter?

• Food travels for how many hourse?

• First part of small intestine?

• Pancreas produces? Which does what?

• The liver ?

• The gallbladder?

• The lining of the SI is covered in?

• Villi & microvilli ?

• Up to ___% of the 10L of food & fluid daily intake is absorbed by the SI

SMALL INTESTINE (MOST IMPORTANT)

This is where:
👉 MOST digestion & absorption happens

• 6 meters long

• 2.5cm diameter

• Food travels 3–6 hours

• First part = duodenum

The duodenum gets help from:

• Pancreas

• Liver

• Gallbladder

• The liver produces bile that emulsifies fats

• The gallbladder stores & secretes the bile

• The lining of the SI is covered in villi which are covered in microvilli

• Villi & microvilli increase the surface area for absorption of nutrients

• Up to 95% of the 10L of food & fluid daily intake is absorbed by the SI

Liver + Gallbladder?

• Liver produces? stores

• Liver detoxifies?

• Gallbladder produces

• If the gallbladder is obstructed

HELPER ORGANS

• Liver produces bile & stores

glycogen (excess sugar) &

vitamins A, B12, & D until

they are needed

• Any excess above that is

converted into body fat

• Liver detoxifies the blood

of harmful chemicals

• Gallbladder produces bile to reduce the size of fat globules (emulsification) in the small intestine

• If the gallbladder is obstructed and bile cannot be produced,

JAUNDICE results → skin & tissues turn yellow

5: LARGE INTESTINE

• The large intestine is also called ?

• LI absorbs (or re-absorbs) ?

• prevents?

• how long?

• diameter?

• Bacteria living in the LI

• Feces are compacted in ? eliminated through?

• Feces are brown because?

5: LARGE INTESTINE (COLON)

• also called the colon

• LI absorbs (or re-absorbs) minerals & water,

• prevents dehydration,

• Human LI is 1m long,

• 7.5cm in diameter

• Bacteria living in the LI transform & compact undigested material to feces

• Feces are compacted in the rectum

• & eliminated through the anus 12-24 hours after ingestion

• Feces are brown because their main component is broken down haemoglobin from red blood cells