The document summarizes the key parts and processes of the human digestive system. It describes the breakdown of food through the mouth, esophagus, stomach, and small and large intestines. Accessory organs like the liver, pancreas and salivary glands produce enzymes and juices to break down lipids, proteins, carbohydrates and other molecules into smaller components that can be absorbed and used by the body. The digestive system breaks food down, filters waste, and moves everything along through peristalsis until undigested waste is eliminated through defecation.

1. Made by: Mariyam

2.  Definition:
The chemical breakdown of complex
biological molecules into their component
parts.
– Lipids to fatty acids
– Proteins to individual amino acids
– Carbohydrates into simple sugars

3.  Function Produces various chemicals to break
down the food.
 Filters out harmful substances.
 Gets rid of solid wastes.

4.  Ingestion Movement
 Digestion
 Absorption
 Further digestion
 Defecation

5.  Main Parts
• Mouth • Esophagus
• Stomach • Small Intestine
• Large Intestine
 Accessory Parts
• Liver • Pancreas
• Gallbladder • Salivary Gland

7.  Mouth
 Pharynx
 Oesophagus
 Stomach
 Small intestine
 Large intestine
 Stomach

9.  There two major processes which take place:
• Mastication (Chewing):
- Human incisors and canines are adapted for
tearing food, while molars are adapted for
grinding food.
- Breaks down large food molecules.
- Increases surface area of food particles.
• Secretion of Saliva:
- Contains salivary amylase (ptyalin) that
digests starch to maltose.
- Provides an alkaline medium.
- Lubricants and moistens food.

11. - it is a skeletal muscle and mixes food with
saliva into a compact mass (BOLUS.)
- LINGUAL FRENULUM attaches the tongue to
the floor of the mouth and prevents posterior
movement of the tongue.
– Mixes and rolls food into tiny mashed up bits
(Bolus)
– Pushes the bolus toward the pharynx and
into the esophagus when swallowing.

13.  produce and secrete saliva into the oral cavity.
– Parotid (beneath the cheeks) This gland produces
SALIVARY AMYLASE (ptyalin), a digestive enzyme.
– Submaxillary/submandibular (below the jaw
bone)
– Sublingual (below the tongue)
 saliva moistens the food and contains enzymes
(salivary amylase) that begins digestion of starch
into smaller polysaccharides.

14. 1. Masseter Muscle
2. Parotid Gland
3. Parotid Duct
4.
Submandibular
Gland
5. Sublingual Gland
6. Lymph Nodes
7. Molar Gland

16.  Swallowing is a coordinated activity of the
tongue, soft palate, pharynx and esophagus.
 Phases
– Food is pushed into the pharynx by the
tongue. (voluntary)
– Tongue blocks the mouth
– Soft palate closes off the nose
– Larynx (Adam’s Apple) rises so the
Epiglottis (a flap of tissue) can close the
opening of the trachea.

18.  A straight muscular tube that is about 10
inches (25 cm) long which connects the
mouth with the stomach
 Food takes about 4 to 8 seconds as it passes
through to the stomach.
 Its walls contain smooth muscles that
contracts in wavy motion (Peristalsis).

20.  It is an involuntary process of muscular
contraction forcing the bolus (food) down to
the stomach.

21.  Acid digestion occurs in the stomach.
 Gastrin, a hormone, stimulates acid release.
 Pepsin, an enzyme that breaks up proteins,
requires an acidic environment to become
active.
 Churns and grinds together the bolus into
smaller pieces.
 Food is mixed with gastric juices
(hydrochloric acid and enzymes) secreted
by the stomach walls.
 HCL helps break down food and kills
bacteria that came along with the food.

24.  Pepsin – major enzyme; converts proteins
into peptides in the presence of HCL.
 Mucus – lubricates food and protects the
gastric lining from strong digestive juices.
 Converts the bolus into a liquid (chyme) after
4 hrs of mechanical and chemical digestion
 Chyme passes through the pyloric sphincter
into the small intestine.

25.  Stomach ulcers cause pain
when the stomach is
empty. These are bacterial
infections that create
ulcerations.
 Acid reflux is often due to
weakness in the sphincter
muscle at the top of the
stomach.

26.  Long (20 ft), coiled tube beneath the
stomach.
Has three parts:
1. Duodenum – upper part; about 10 in;
connected to the stomach.
– where the digestive juices from the
pancreas and the liver combine with chyme
making it thin and watery.
1. Jejunum – about 8 ft
2. Ileum – about 12 ft

27.  Takes about 4 – 8 hrs to complete its journey.
 Mucosa (inner wall) – secretes several
enzymes that acts on the food.
 Where the pancreatic enzymes are emptied
into.
 Digested nutrients are absorbed through
intestinal walls.
 Absorbed materials cross the mucosa into the
blood then other parts of the body for
storage or further chemical change.

28.  Has folded inner walls covered with fingerlike
projections (villi; sing. – villus)
 Each villus has tinier projections called
microvilli that absorbs digested food.
 Villi and microvilli increases the surface area
of the small intestine for greater absorption.
 Peristalsis moves the undigested food to the
large intestine.

33.  Alkaline digestion
takes place in the
upper small
intestine, the
duodenum.
 Enzymes from the
pancreas require
an alkaline
environment to be
active.

34.  Pancreas releases
pancreatic juice,
containing
bicarbonate, lipases,
proteases, and
amylase.
 The liver makes bile,
which emulsifies fats.
Bile is made from
cholesterol, which is
made in the liver

37.  a.k.a. Colon larger diameter, but shorter (5 ft)
 Water is absorbed from the undigested food
making the waste harder until it becomes
solid.
 Waste stays for 10 – 12 hours.
 Waste is pushed into the expanded portion
(rectum) of the large intestine.
 Solid waste stays in the rectum until it is
excreted through the anus as feces.
 Appendix hangs on the right side of the
large intestine.

40. 1. The mouth
2. The stomach
3. The small intestines
4. The large intestines

41. 1. Mouth
2. Stomach
3. Small intestine
4. Large intestine

42. 1. To protect the intestinal lining.
2. To vastly increase the intestine’s surface
area.
3. To block acids coming from the stomach.

45. THANK YOU !