1. 13-14th week: The digestive
system
Plan
The digestive system
Digestive system functions
Oral cavity
Stomach digestion
Pancreas and gallbladder
Liver function
Small intestine
Large intestine
Chemical digestion
Lecturer: Ablaikhanova N.T.
Assistant: Balmaganbet Zarina
2. What is the digestive
system?
The digestive system is made up of the
gastrointestinal (GI) tract—also called the digestive
tract—and the liver, pancreas, and gallbladder. The
GI tract is a series of hollow organs joined in a long,
twisting tube from the mouth to the anus. The
hollow organs that make up the GI tract are the
mouth, esophagus, stomach, small intestine, large
intestine—which includes the rectum—and anus.
Food enters the mouth and passes to the anus
through the hollow organs of the GI tract. The liver,
pancreas, and gallbladder are the solid organs of the
digestive system. The digestive system helps the
body digest food.
3.
4. Digestion
Endogenic Exogenic
Human usually get the nutrients
they need from outside
Human use organic nutrients in his
cells to ensure the normal
functioning of the organs and
tissues contained in them.
5. Types of digestive system
• Autolysis is the enzymatic digestion of cells by the action of its own enzymes, and it mostly occurs in dying
or dead cells. It has previously been suggested that prolonged procedure time could lead to autolytic changes
from the periphery of the endoscopic submucosal dissection specimens.
Autolytic digestion
• The bacteria also produce vitamins and help protect the body from diseases. The whole population of
bacteria in our bodies is called the human microbiota.
• The relationship between you and your gut bacteria is symbiotic. This means that both you and the bacteria
benefit. Your bacteria receive a safe home and plenty to eat, and in return they help you break down food to
get the nutrients that you need to survive and grow.
• Symbiosis between microbes and their mammalian host is vital to maintaining homeostasis. Symbiotic
microbes within the gastrointestinal tract provide an array of benefits to the host, including promotion of
host immunity.
Symbiotic digestion
6. 1. Ingestion
2. Mechanical processing
3. Digestion
4. Secretion
5. Absorption
6. Excretion
The Digestive Tract
Six Functions of the Digestive System
7. The Digestive Tract
• Ingestion
– Occurs when materials enter digestive
tract via the
mouth
• Mechanical Processing
– Crushing and shearing
– Makes materials easier to propel along
digestive
tract
• Digestion
– The chemical breakdown of food into
small organic
fragments for absorption by digestive
epithelium
The Digestive Tract
• Secretion
– Is the release of water, acids, enzymes, buffers, and
salts
– By epithelium of digestive tract
– By glandular organs
• Absorption
– Movement of organic substrates, electrolytes,
vitamins, and water
–Across digestive epithelium tissue
–Into the interstitial fluid of digestive tract
• Excretion
– Removal of waste products from body fluids
– Process called defecation removes feces
8. • The oral cavity, or mouth, is the point of entry of food into the
digestive system. The food is broken into smaller particles by mastication,
the chewing action of the teeth. All mammals have teeth and can chew
their food.
9.
10. The Oral Cavity Functions to
Provide
• sensory analysis of food material
before swallowing
• mechanical processing via the action
of the teeth, tongue, and palatal
surfaces
• lubrication by mixing food material
with mucus and salivary gland
secretion
• limited digestion of carbohydrates
and lipids
13. Saliva secreted by salivary glands aids the mechanical and chemical process of digestion.
Saliva is about 99% water and not only moistens food but cleanses the mouth, dissolves food
chemicals so they can be tasted, and contains enzymes that start the chemical breakdown of
starchy foods.
There are three pairs of salivary glands: parotid, sublingual, and submandibular (also called the
submaxillary gland).
Function of the saliva
1.Chemical digestion: breaks down starch by the function of “salivary amylase”
2.Helps chewing and swallowing
3.Lubricating effect: moisturizes the inside of the mouth and creates smoother speech
4.Solvent effect: dissolves food and allows the tongue to taste food
5.Cleaning effect: washes away food debris and bacteria remaining in the mouth
6.Antibacterial effect: Lysozyme, peroxidase and lactoferrin fight against pathogenic microorganisms
7.pH buffering effect: Prevents sudden changes in pH
8.Supplies minerals, including calcium and phosphorus, to teeth
14. • What are the three major salivary glands?
• You have three major pairs of salivary glands,
including your:
• Sublingual glands: These are below either side of
your tongue, under the floor of your mouth.
• Submandibular glands: Located below your jaw,
your submandibular salivary glands consist of two parts:
the superficial lobe and the deep lobe. Like your
sublingual glands, the saliva produced in your
submandibular glands enter your mouth from under your
tongue.
• Parotid glands: Your parotid glands are just in front
of your ears. Similar to your submandibular glands, your
parotid glands have two parts: superficial and deep. The
saliva produced by your parotid glands enters your
mouth from small ducts near your upper molars.
What is the role of salivary glands?
The main salivary gland function is saliva
production. Saliva plays an important role in
supporting your oral and overall health. For example,
saliva:
•Keeps your mouth and throat lubricated and
comfortable.
•Moistens food so it’s easier to swallow.
•Contains an enzyme called amylase, which helps
your stomach break down starches in food.
•Keeps your mouth clean.
•Helps reduce your risk of cavities and gum disease.
•Helps maintain the pH balance in your mouth.
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19. Your stomach is a muscular organ that digests food. It
is part of your gastrointestinal (GI) tract. When your
stomach receives food, it contracts and produces acids
and enzymes that break down food. When your stomach
has broken down food, it passes it to your small intestine.
Stomach digestion
30. Small intestine
digestion
The small intestine is a tubular structure
within the abdominal cavity that carries
the food in continuation with the
stomach up to the colon from where the
large intestine carries it to the rectum
and out of the body via the anus. The
main function of this organ is to aid in
digestion.
As a person grows the small intestine
increases 20 times in length from about
200 cm in a newborn to almost 6 m in
an adult. The length of the small
intestine is approximated by three times
the length of the infant, or height of the
child or adult.
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36. The Brunner glands, which empty into the
intestinal glands, secrete an alkaline fluid
composed of mucin, which exerts a
physiologic anti- acid function by coating the
duodenal epithelium, therefore protecting it
from the acid chyme of the stomach.
Lieberkühn glands, occupying the mucous
membrane, secrete digestive enzymes,
provide outlet ports for Brunner glands,
and produce cells that replace surface-
membrane cells shed from the tips of villi.
37. During digestion, your pancreas makes pancreatic juices called
enzymes. These enzymes break down sugars, fats, and starches.
Your pancreas also helps your digestive system by making
hormones.
