DIGESTIVE SYSTEM (Overview of Metabolism)

DIGESTIVE SYSTEM
Stella Maris Polytechnic University
Mother Patern College of Health Sciences
UN Drive Randal Street
Monrovia, Liberia
GROUP 3 MEMBERS:
1. Rosemarie Worjloh - 11270
2. Elvis K. Goodridge - 11269
3. Morris Cooper - 11277
4. Elaine Boakai - 11258
5. Yamah Paypay – 11183
6. Famatta A. Sannor – 11267

Presentation Outline
 Gastrointestinal/Digestive System
 Overview of the structure and function of the digestive tract
 Histological organization of the digestive tract
 Movement of digestive materials
 Control of digestive functions
 Oral cavity
 Tongue, salivary glands, saliva, teeth
 Types of teeth and dental succession
 The pharynx and esophagus
 Stomach
 Anatomy of the stomach
 Histology of the stomach
 Regulation of gastric activities
 Digestion and absorption in the stomach

Presentation Outline Cont’d
 Small intestine and associated glandular organs
 liver anatomy (physiology and histology)
 gallbladder (anatomy and physiology)
 large intestine (histology and physiology)
 digestion and absorption
 processing and absorption of nutrients
 carbohydrate digestion and absorption
 absorption of protein, lipids, vitamin and ion
 Metabolism
(carbohydrate, protein, lipid, and nucleic)

Presentation Objectives:
After concluding this presentation, we expect our audience to
understand:
 The pathway of the digestive system
 The importance of GI system
 Functions of its organs
 The difference between alimentary Organs and associate organs
 How Macromolecules are broken down

Overview of the Digestive system
The digestion system is the organ
system that:
- processes food
- extracts nutrients from it, and
- eliminates the residue

Functions Of the Digestive
1. Ingestion or take in
2. Deglutition or swallow
3. Digestion or breakdown
4. Absorption or take into tissue
5. Assimilation or movement
6. Elimination or release

Types of Digestion
The are two types of digestion
Mechanical digestion
or Physical digestion
- Process takes place in the mouth.
Chemical digestion
- Begins in the stomach and part of the intestines

Divisions of the Digestive System
Digestive system has two divisions:
1. Alimentary Organs or Main Organ of Digestion
Mouth
Pharynx & Esophagus
Stomach
Intestines

Divisions of the Digestive System
2. Accessory Organs
Salivary gland
Liver
Gallbladder
Pancreas

Oral Cavity
 The oral cavity or mouth is the first part of the human
digestive tract, which contains:
 lips,
 teeth,
 tongue,
 hard and soft palate,
 tonsils,
 three pairs of salivary glands.
 The oral cavity is bounded by the lips and cheeks and
contains the teeth and tongue.

Oral Cavity cont’d
 The Tongue- is a large, muscular organ
that occupies most of the oral cavity.

 Salivary Glands - The salivary glands have
branching ducts with clusters of alveoli, resembling
grapes, at the ends of the ducts.
 There are three pairs of salivary glands, they are:
 parotid,
 submandibular
 sublingual glands.
 The Saliva helps keep the oral cavity moist and
contains enzymes that begin the process of chemical
digestion

Saliva
 Saliva (spit) is a bodily fluid that has several important functions.
For example, it kick starts digestion, helps you chew and swallow
food, and protects your teeth. Saliva is mainly water, but it also
has several proteins and other substances that help keep your
mouth and body healthy.
 The saliva helps keep the oral cavity moist and contains enzymes
that begin the process of chemical digestion.
 Saliva is 99% water and 1% proteins, electrolytes and other substances.
 Saliva (spit) comes from your salivary glands. They produce saliva and release it into your mouth through
ducts, or small openings.

 The Teeth
Our teeth plays a big role in digestion.
They cut and crush foods, making them
easier to swallow.
 Though they look more like bones, but
teeth are actually ectodermal organs.
 We have different types of teeth, and
each type serves an important purposes.
The four types of teeth include:

Pharynx & Esophagus
Elaine Boakai

Pharynx Cont’d
Structure
 Nasopharynx
 Oropharynx
 Laryngopharynx
 Tonsils
 Pharyngeal walls
 Adenoids
 Mucosa
Function
 Swallowing
 Air passage
 sound Production

Pharynx Cont’d
 The Musculature of the Pharynx is extremely
crucial for the Pharynx, muscles of the
Pharynx are of four (4) constrictor muscles:
 Superior, Middle, Inferior and cricopharynx
 three longitudinal muscles:
 Stylopharyngeus
 platopharyngeus
 salpingopharyngeus

Blood supply of the pharynx
 External Carotid Artery
 Superior Thyroid Artery
 Internal Carotid Artery
 Palatine Artery
 Facial Artery
Pharynx Cont’d

Esophagus
FUNCTION
 Protection
 Sensation
 Lubrication
 Digestion

STOMACH & SMALL INTESTINE
Morris Cooper

STOMACH
 Expanded part of the digestive tract between the oesophagus and
small intestine.
 A J-shaped structure just about the size or your "Fist" when empty.
 Specialized for the accumulation of ingested food, chemically and
mechanically prepares for digestion and passage into the duodenum.
 Acts as a food blender and reservoir; its chief function is enzymatic
digestion.
 Holds 4 Liters of food and fluid.

REGIONS OF THE STOMACH
 There are 4 major Regions of the
stomach:
 Cardia- (Connects the esophagus to the
stomach)
 Fundus-(Top portion)
 Body(Corpus)-(middle portion)
 Pylorus-(Allows food to exit)

Clinical Correlation
Gastritis
 It’s an uncomfortable digestive problem caused by stomach inflammation and erosion of the lining of
the stomach (called the gastric mucosa).

Small Intestine
 Long coiled tube about (20ft) in adult, that is part of the digestive system.
 Extend from the pylorus to the ileocecal junction.
 Line with tiny hair-liked structures called "Villi"
 Primary site for absorption of nutrients
from ingested food.

Regions of the Small Intestine
 There are 3 Major regions of the small
intestine:
 Duodenum-(1st part of the small
intestine, shortest, widest and more fixed
part.)
 Jejunum- ( Middle part)
 Ileum- (3rd part which ends at the
ileocecal junction)

DUODENUM
 First and shortest section of the small intestine, measures
approximately (10inches) in length.
 Helps break down food with enzymes.
 Contains tubular submucosal glands called "Brunner's
glands"(lubricates lining of intestine)

JEJUNUM
 Second longest section of the small intestine,
measures around 8 feet' in length.
 Primarily, absorbs and transport nutrients of
digested food.
 Helps with PH levels

Ileum
 Final and longest section of the small intestine, measures
approximately 12 feet in length.
 Further absorb nutrients, bile salts and vitamin B12
 Contains specialized lymphoid tissue called "Peyer's
Patches"

Clinical Correlation
Celiac Disease
Is a digestion autoimmune
disorder that results in
damage to the lining of the
small intestine, when food
are eaten.

LARGE INTESTINE & LIVER
Rosemarie Worjloh

FUNCTION
 Metabolism
 Detoxification
 Storage
 Immune function
 Bile production

CLINICAL CORRELATION
HEPATITIS
 Causes: viruses, toxins, alcohol or
autoimmune dis orders.
 Symptoms: Jaundice, fatigue, nausea,
abdominal pain, and loss of appetite
 Treatment: antiviral medication, or in
severe cases, a liver transplant.

FUNCTION
 Storage of bile
 Regulation of bile flow
 Bile PH regulation
 Absorption of certain vitamins in
our body.

Cholecystitis
 Causes: Inflammation of the
gallbladder
 Symptoms: severe abdominal pain,
fever, nausea, vomiting.
 Treatment: Antibiotics for infection,
and in severe cases, surgery to
remove the gallbladder.

Pancreas
An important gland in the digestive and
endocrine systems of the human body.
Located behind the stomach in the abdomen.
Performs both exocrine and endocrine
functions.

Pancreas Cont’d
 Exocrine function:
Involves the production of digestive enzymes that are
released into the small intestine through a duct. They
are:
 Amylase
 Protease
 Lipase

Pancreas Cont’d
Endocrine function:
Involves producing hormones that regulate
blood sugar levels. The two hormones
produced by the pancreas for this purpose are:
 Insulin
 Glucagon

Pancreatitis
 Causes: Gallstones, alcohol abuse or certain
medications
 Symptoms: Severe abdominal pain, nausea,
vomiting, fever, and rapid pulse.
 Treatment: Intravenous fluids, and gallstone
removal or alcohol cessation.

FUNCTION
Absorption of water and electrolytes
Formation and storage of feces
Gut flora management
Synthesis of vitamins
Immune function

Digestive Pathway
METABOLISM of the Macromolecules
Elvis K. Goodridge

DIGESTIVE PATHWAY
 INGESTION
 MECHANICAL/CHEMICAL
DIGESTION
 DEGLUTITION
 ABSORPTION
 ELIMINATION

METABOLISIM
The set of chemical processes that occurs
on an organism to produce and sustain
life.
Catabolic: they are usually exergonic.
Anabolic: they are usually endogenic.

Carbohydrates
Mouth (Mastication)
- STARCH
 Parotid Gland
-alpha-Amylase (ptyalin)
Stomach
- Responses are inhibited

Carbohydrate cont’d
Small Intestine
Pancreas
- Bicarbonate rich juice
- Amylase
Villi
- Enterocytes
Brush border enzymes
- Maltase
- Sucrase
- Lactase
- Isomaltase

Carbohydrate cont’d
Large Intestine
- Fiber (microbiome)
microbial Fermentation
Enterocytes
GPCR-41 (Glucagon-like peptide)
GPCR-43 (Peptide Tyrosine Tyrosine)
Adipocytes
GPCR-43
Undigested carbs
-excreted

Fate of carbohydrates
Glucose
- Glycolysis
- Krebs Cycle
- Electron Transport Chain
- Glycogen
 Galactose
-Leloir pathway
Glycogen
Glucose
Fructose
Glycogen
Glucose

LIPIDS
 Dietary lipids
- Triglyceride
- Phospholipids
- Cholesterol ester
 Mouth & Stomach
 Lipase
-Fat Globule

Lipids cont’d
Small intestine
Hormones;
 Secretin
 Cholecystokinin
Emulsification
-Bile
Bile salt
Lecithin

Lipids cont’d
 Pancreas
Enzymes;
 Lipase
 Co-Lipase
 Phospholipase A2
 cholesterol esterase
End Product in the intestinal lumen
 micelles

 Enterocyte:
- Smooth ER
synthesis of
Triglyceride
Synthesis of CE
- Rough ER
adds a protein coat
APO protein complex
- Chylomicron
Lipids cont’d

 Peripheral
Lipoprotein Lipase
APO C-2
skeletal/Cardiac Muscle
oxidation
Adipocytes
storage
Liver
Bile synthesis
Storage
Fate of Chylomicron

Protein
 MOUTH
- Not digested
 STOMACH
0.8 – 2.5
- Parietal Cell
Hydrochloric
Denatured Proteins
- Chief Cells
Pepsinogen
pepsin

Protein Degradation
Small Intestine
Pancreas
- Bicarbonate rich juice
- Proteases:
- Trypsinogen
- Chymotrypsinogen
- Pre-elastase
- Pre-corboxypeptidase

Protein cont’d
Villi
- Enterocytes
Brush border enzymes:
Aminopeptidase
Dipeptidase
Inner enterocyte
peptidase

Nucleic acid
 Mouth
Unchanged
 Stomach
Denatured
 Small Intestine
Pancreas
Nucleases
Brush Border Enzymes:
-Phosphatase
- Nucleosidase

SUMMARY
 The Gastro intestinal system is a complex system that process food
and extract nutrients.
 Digestion is mechanical and chemical.
 Most nutrients after absorption travel to the liver for metabolism.
 Nutrients are either used to give energy or supply components for
synthesis.
 The tract begins with the oral cavity and ends the anus.

REFERENCE
 Hall, J. & Guyton, A (2006). Medical physiology. Elviers
 Harvey, R. (2017). Lippincott’s illustrated reviews: Biochemistry.
7th
Edition. Wolters Kluwer Health.
 Joshi, V. & Joshi, M. S (2010). Physiology: Prep manual for
Undergraduates. Reed Elseveir india Private Limit.
 Sherwood, L (2016). Human physiology: From Cells to systems.
Gary Lumberick.
 The images are retrieved from: www.google.com
 Chat GPT bot 2.47

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and endure.”
-Gojo Saturo-
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DIGESTIVE SYSTEM (Overview of Metabolism)

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