PowerPoint presentation to explain Digestive system. Contains videos and activities

2. • Identify the main organs of the digestive system
• Describe the structure and function of each organ in the digestion process
• Explain the mechanical and chemical involvement in digestion
• Explain how nutrients are absorbed and waste is eliminated within the digestive
system.
• Identify the importance of other body systems in digestion.

3. Fill in the crossword puzzle

4. The Alimentary canal:
• Mouth
• Pharynx
• Oesophagus
• Stomach
• Small intestine
• Large intestine Rectum and anal canal
The Accessory Organs;
• Three pairs of salivary glands
• The pancreas
• The liver and biliary tract

5. • Ingestion – Taking in food through the mouth
• Propulsion – Mixes and moves along the alimentary tract
• Digestion – Mechanical breakdown in the stomach, chemical digestion of
food into small molecules by enzymes
• Absorption – Digested food substances pass through the wall of some
organs into blood and lymph capillaries for circulation and use by body
cells
• Elimination – Food eaten but can’t be digested and absorbed is
eliminated

6. https://youtu.be/_QYwscALNng

8. AKA the Gastrointestinal Tract and
Digestive Tract
The walls are made up of 4 layers:
• Adventitia or Serosa – Outer covering
• Muscle layer
• Submucosa
• Mucosa – lining
https://youtu.be/R-OhCLIkP5U

9. Specialised cells or glands
release secretions
Saliva – From the Salivary glands
Gastric Juice – From the Gastric Glands
Intestinal Juice – From the Intestinal Glands
Pancreatic Juice – From the Pancreas
Bile – From the Liver
They all contain enzymes that chemically
break down food
Nerve Supply
• The vagus nerve and sacral nerve –
These are both Parasympathetic
which increases muscle activity and
secretions.
• Sympathetic nervous supply – From
the spinal cord, thorax, stomach and
pelvic area. These decrease muscle
activity and decrease secretions

12. • The mouth, also known as the oral cavity, is where food enters
the body and begins its journey through the digestive system.
• The teeth cut and grind food into smaller pieces.
• The salivary glands produce saliva which helps to moisten food
and begin the digestion of carbohydrates.
• The tongue helps to push food pieces into the pharynx.

13. Mechanical Digestion
• Teeth and tongue break food down into
smaller pieces
Chemical Digestion
• Salivary glands produce saliva
• Amylase (enzyme) in saliva begin to
break food down
• Amylase converts starch into glucose.
Your body
produces 1.5L
of saliva each
day!

14. • The oesophagus is a muscular tube connecting the pharynx to the stomach.
• Wave-like peristalsis movements force the food into the stomach.
• At the lower end of the oesophagus is a muscular ring called the oesophageal sphincter which
closes off the end of the oesophagus.
• This traps food in the stomach and stops it re-entering the oesophagus.

15. • The pharynx, or throat, plays a dual role.
• It is a common passageway for air entering the respiratory
system and for food and fluids entering the digestive
system.
• The pharynx contains a flap of tissue known as the
epiglottis that acts as a switch to direct food to the
oesophagus and air to the larynx.

16. • The stomach is divided into four regions: the cardia,
fundus, body, and pylorus.
• It is three muscle layers:
• The longitudinal and circular layers are found throughout
the alimentary canal and move food along using peristaltic
contractions.
• The third, oblique layer in the stomach churns food to
break it down.

17. • The small intestine has three regions: the
duodenum, the jejunum, and the ileum.
• The duodenum is the uppermost part of the small
intestine and only 25-35 cm long.
• During digestion it receives chyme from the
stomach and bile, enzymes, and other digestive
fluids from the liver and the pancreas.

18. • The jejunum is the middle portion of the small intestine (about 2.5
m long and 4 cm wide).
• The ileum is the lower segment and the longest of the three
(about 3.5 m long).
• Finger-like projections called villi line the interior wall throughout
the small intestine.
• The villi absorb most of the nutrients broken down by the
digestive fluids.

19. • Ducts from the pancreas, gallbladder and liver empty
pancreatic juice, bile, and other digestive fluids into the
duodenum.
• The duodenum is the uppermost part of the small intestine, so
it receives chyme from the stomach.
• The duodenum is where most chemical digestion occurs and
where the absorption of vital nutrients, vitamins, & minerals
begins.

20. • Has three sections, it starts with the duodenum, which
has a role in neutralising the low pH of the stomach.
• It then continues into the jejunum, which is where a lot
of absorption of nutrients occurs.
• The final section is the ileum, which connects on to the
large intestine, some fluids are absorbed here.

21. • The regions of the large intestine are the appendix,
cecum, ascending colon, transverse colon,
descending colon, sigmoid colon, rectum, and anal
canal.
• The large intestine absorbs water, electrolytes, and
vitamins that remain after chyme is passed from the
small intestine. It compacts and temporarily stores
faeces for defecation.

22. • The main function of the liver in digestion is the production of bile and its secretion into the
small intestine.
• Bile, a mixture of water, bile salts, cholesterol, and the pigment bilirubin, travels through the
bile ducts and is released into the duodenum where it emulsifies large masses of fat.
• This involves turning these large masses of fat into smaller pieces that are easier for the body
to digest.

23. • The gallbladder is used to store and
recycle excess bile from the small
intestine so that it can be reused for
the digestion of subsequent meals.

24. • The pancreas secretes digestive juices into the small
intestine to complete the chemical digestion of foods.
• This fluid contains enzymes that break down fats,
proteins and carbohydrates.
• It also contains sodium bicarbonate which neutralises
acid in the stomach.

26. Enjoy your Lunch!! 🤣😜💩