Unit-II, Chapter_1-Digestive system.ppt

THE DIGESTIVE SYSTEM
Represented By,
Mr. Audumbar Mali,
(Asst. Prof.)
Sahyadri College of Pharmacy
Methwade
1

Chapter Overview
• Gastrointestinal (GI) Tract
• Accessory Organs of the Head
• Swallowing
• Stomach
• Accessory Organs of the Abdomen
• Small Intestine
• Large Intestine
• Phases of Digestion
• Food Molecules
• Metabolism 2

Essential Terms
Digestion
 process of mechanically or chemically breaking down
food.
absorption
 passage of small molecules into blood and lymph.
digestive system: -
 organs which carry out process of digestion and
absorption
metabolism
 all the chemical reactions of the body
3
Anatomy and Physiology of diagestive system

Introduction
Digestive System
1. Composed of GI tract and organs
2. Breaks down ingested food for use by
the body
3. Digestion occurs by mechanical and
chemical mechanisms
4. Excretes waste products or feces
through process of defecation
4

Gastrointestinal (GI)
Tract
5

GI Tract / Alimentary Canal
 Continuous tube from mouth to anus
 Mouth
 Pharynx
 Esophagus
 Stomach
 Small intestine
 Large intestine
 Anus
6

Accessory Digestive Organs
 Provide mechanical and chemical mechanis
ms to aid digestion
 Teeth
 Tongue
 Salivary glands
 Liver
 Gallbladder
 Pancreas
7

Figure 23.1
8
Anatomy and Physiology of diage
stive system

Functions of Digestive System
1. Ingestion
2. Secretion
3. Mixing and propulsion
• Motility
4. Digestion
• Mechanical and chemical
5. Absorption
6. Defecation
9

Physiological Processes of the Digestiv
e Tract - simplified
10

Layers of GI Tract
 Same in all areas of GI tract
 From deep to superficial:
 Mucosa
 Submucosa
 Muscularis
 Serosa
11

#1 Mucosa
Epithelium
Lamina propria
Muscularis
mucosae
#2 Submucosa
Submucosal
nerve plexus
#3 Muscularis
Inner circular layer
Myenteric
nerve plexus
Outer longitudinal
layer
#4 Serosa or Adventitia
Vein, artery,
lymph vessel
(within mesentery)
(a) Tunics
Lumen
Design of the Four Layers in the GI System
13
stive system

Layers of GI Tract
 Mucosa
 Epithelium
 Type varies
 Lamina propria – areolar connective tissue
 MALT – mucus-associated lymphatic tissue
 Muscularis mucosae – smooth muscle
 Submucosa
 Areolar connective tissue
 Blood and lymphatic vessels
 Neurons – submucosal plexus
14

Layers of GI Tract
 Muscularis
 Skeletal and smooth muscle
 Neurons – myenteric plexus
 Serosa
 Areolar and simple squamous epithelium
 Visceral peritoneum
15

Peritoneum: The peritoneum is a membrane made up of two layers.
One layer lines the cavity and the other layer lines the organs.
The peritoneum helps support the organs in the abdominal cavity and
also allows nerves, blood vessels, and lymph vessels to pass through to
the organs
 Mesothelium
 Parietal peritoneum
 Visceral peritoneum
 Peritoneal cavity
 Retroperitoneal
16

Folds of Peritoneum
 Greater omentum
 Adipose tissue
 Falciform ligament
 Liver to anterior abdominal wall
 Lesser omentum
 Mesentery
 Small intestine to posterior abdominal wall
 Mesocolon
17

Figure 23.3a
18
stive system

Figure 23.3b
19
stive system

Figure 23.3c
20
stive system

Figure 23.3d
21
stive system

Neural Innervation of GI Tract
 Regulated by autonomic nervous system
 Enteric division
 Myenteric plexus
 Submucosal plexus / plexus of Meissner
 Able to function independently from rest of nervous
system
 Linked to CNS by extrinsic sympathetic and parasympat
hetic nerves
 Sympathetic nerves decrease GI secretions & motility
 Parasympathetic nerves increase GI secretion and motili
ty 22

Accessory Organs of
the Head
23

Mouth Parts of Digestive System
 Mouth formed by several parts:
 Cheeks
 Lips
 Orbicularis
 Vestibule
 Oral cavity
 Hard and soft palate
 Palatoglossal and palatopharyngeal arch
24

Figure 23.4
25
stive system

Tongue
 Skeletal muscle and mucous membrane
 Helps form floor of oral cavity
 Extrinsic muscles
 Intrinsic muscles
 Lingual frenulum
 Papillae
 Lingual glands
 Lingual lipase
26

 The tongue is a muscular organ in the mouth. The
tongue is covered with moist, pink tissue called
mucosa. Tiny bumps called papillae give the tongue
its rough texture. Thousands of taste buds cover the
surfaces of the papillae. Taste buds are collections of
nerve-like cells that connect to nerves running into
the brain.
 The tongue is anchored to the mouth by webs of
tough tissue and mucosa. In the back of the mouth,
the tongue is anchored into the hyoid bone. The
tongue is vital for chewing and swallowing food, as
well as for speech.
Anatomy and Physiology of diagestive system 27

 The four common tastes are sweet,
sour, bitter, and salty. The tongue
has many nerves that help detect
and transmit taste signals to the
brain. Because of this, all parts of the
tongue can detect these four
common tastes.
Anatomy and Physiology of diagestive system 28

Salivary Glands
 Release saliva to oral cavity by ducts
 3 pairs of salivary glands
 Parotid: inferior and anterior to ears
 Submandibular: base of the tongue
 Sublingual: superior to sub mandibular
gland
29

Composition of Saliva
 99.5 % water
 0.5% other solutes
 Ions: Na, K, CL etc
 Mucus
 Immunoglobulin A
 Enzymes: amylase, lysosome
 Salivation controlled by autonomic
nervous system
 Stimulated by various mechanisms 30

Role of saliva
 Water provide a medium to dissolve food that
gives taste and begin digestive reaction
 Mucus lubricate the food
 IgA: prevent attachment of microbe
 Lysozyme: kill microbes, protect from
infection.
31

Regulation
 Secretion of saliva is control by ANS
 daily secret 1-1.5L
 Normally PNS constantly stimulate release of
secretion control by ( VII and IX ) facial and
glossopharyngeal
 The feel., taste , smell, sight, sound or thought
of food stimulate saliva
32

Figure 23.5
33
stive system

Teeth
 External regions
1. Crown
2. Root
3. Neck
 Internal components
1. Enamel
2. Dentin: # Cementum: (The main function of cementum is
to provide attachment to the collagen fibres present in the
periodontal ligament. This helps maintain the integrity of
the root and its position in the gum and bone.Cementum is
also deeply involved in the repair and regeneration of teeth.
)
3. Pulp cavity
 Pulp Root canal.
34

Figure 23.6
35
stive system

Teeth
 Deciduous teeth – first set
 Permanent teeth – secondary
 Carry out mechanical digestion by mastication
 Creates bolus
 Salivary amylase
 Breakdown starch
 Lingual lipase
 Breakdown triglycerides
36

Figure 23.7
37
stive system

Swallowing
39

Pharynx
 Funnel shaped tube that extend from intern
al to esophagus posteriorly and larynx an
teriorly.
 Composed of skeletal muscle
 Lined by mucous membrane
 Nasopharynx
 Oropharynx
 Laryngopharynx
40

Esophagus
 Collapsible muscular tube through esophageal
of diaphragm
 25cm long begins with laryngopharynx to
stomach.
 Mucosa
 Submucosa contains areolar connective tissue
 Muscularis
 Skeletal muscle
 Upper and lower esophageal sphincter.
 Adventitia
 Attaches esophagus to nearby structures
 Secrets mucus and transports food
41

Deglutition (i.e. process of
swallowing.)
Stages of swallowing
 Voluntary
 Mouth to oropharynx (i. e. the part of the pharynx that lies bet
ween the soft palate and the hyoid bone.)
 Pharyngeal
 Deglutition center in medulla oblongata and pons (i. e. the part of the
brainstem that links the medulla oblongata and the thalamus.)
 Involuntary
 Esophageal
 Involuntary
 Peristaltic contractions
43

Figure 23.9a,b
44
stive system

Figure 23.9c
45
stive system

Stomach
 J shaped enlargement of GIT in epigastric,
umbilical, L hypochondriac regions
 esophagus to duodenum
47

Stomach
 Serves as mixing chamber and storage area for
ingested food
 Allow for increased volume
 4 main regions
1. Cardia
2. Fundus
3. Body
4. Pylorus
 Pyloric antrum connect to stomach and canal duodenum
 Pyloric sphincter
 Lesser and greater curvatures 48

Stomach Histology
1. Mucosa
 Surface mucous cells
 Lamina propria
 Muscularis mucosae
 Gastric glands and pits
Parietal cells: intrinsic factor , hcl
Chief cells: pepsin and gastric Lipase
G cells: gastric
2. Submucosa – areolar connective tissue
3. Muscularis
 3 layers of smooth muscle
4. Serosa 50

Figure 23.11a
51
stive system

Figure 23.11b
52
stive system

Figure 23.11c
53
stive system

Mechanical and Chemical Digestion
 Mixing waves caused by peristaltic movement
 Chyme released in process of gastric emptying
 Proton pumps bring H+ into the lumen and K into
cell, at same time K and Cl diffuse out through the
K & Cl channels
 Carbonic anhydrase forms carbonic acid to
provide H+ and bicarbonate ions (HCO3
-)
54

Figure 23.12
55
stive system

Mechanical and Chemical Digestion
 Chemical digestion stimulated by nervous
system.
 Parasympathetic neurons release
acetylcholine.
 Works with gastric system.
 HCl released in presence of histamine
 Pepsin begins digestion of proteins
 Stomach protected by alkaline mucus secretion
 Gastric lipase digests triglycerides
 Few molecules absorbed by stomach
 Water, ions, short-chain fatty acids, alcohol
56

59

Accessory Organs of
the Abdomen
60

Pancreas
 Retroperitoneal, 12-15 cm long and 2.5 cm thick
 Produces secretions to aid digestion
 Head
 Body
 Tail
 Pancreatic duct: -
 Hepatopancreatic ampulla
 Sphincter of the hepatopancreatic ampulla,
 Regulates passage of pancreatic juice and bile
 Accessory duct.
61

Figure 23.13a
62
stive system

Histology of Pancreas
 Glandular epithelial cells
 99% exocrine clusters
 Secrete pancreatic juice
 Fluid and enzymes
 Pancreatic islets (islets of Langerhans)
 1% endocrine cells
 Hormones
 Glucagon
 Insulin
 Somatostatin
 Pancreatic polypeptide 65

Pancreatic Juice
 1200-1500 mL /day
 pH 7.1-8.2
 Water
 Salts
 Sodium bicarbonate
 Enzymes
 Pancreatic amylase
 Trypsin
 Entereokinase
 Chymotrypsin
 Carboxypeptidase
 Elastase
 Pancreatic lipase
 Ribonuclease and deoxyribonuclease 66

Liver and Gallbladder
 Liver second larges organ,
 Largest gland at 1.4 kg.
 Located inferior to diaphragm and took most of
the space of left hypochondriac region.
 Gallbladder: pea shaped sac 7-10cm long
 Closely associated with liver
67

Anatomy of Liver
 Right (large) and left (small) lobe
separated by falciform ligament.
 Round ligament,
 Remnant of umbilical vein,
 coronary ligaments,
68

Histology of Liver
Six side structure consist of
 Hepatocytes radiating from central vein
 Sinusoids
 Reticulo endothelial cells: Stationary
phagocytes.
69

Figure 23.14a
70
stive system

Figure 23.14b
71
stive system

Bile Duct System
 Bile secreted by hepatocytes
 Bile ducts
 Right and left hepatic ducts
 Common hepatic duct
 Common bile duct
 Gallbladder for temporary storage of bile
 Cystic duct
72

Blood Supply of Liver
 Hepatic artery provides oxygenated blood
 Hepatic portal vein provides deoxygenated
blood.
 Nutrients, drugs, toxins, microbes.
 Hepatic artery and vein carry blood to sinusoids
 Substances exchanged by hepatocytes.
 Blood drains to central vein and eventually hepatic
vein.
 Portal triad
 Hepatic portal vein
 Hepatic artery
 Bile duct 73

Bile
 800-1000 mL/day
 pH 7.6 – 8.6
 Water
 Bile acids
 Bile salts
 Emulsification
 Cholesterol
 Lecithin
 Bile pigments
 Bilirubin
 Stercobilin 75

Liver Functions
 Metabolism of:
 Carbohydrates,
 Lipids,
 Proteins.
 Process drugs and hormones: activation/ inactivation
 Excrete bilirubin.
 Synthesize bile salts: emulsification
 Storage
 Glycogen,
 Vitamins,
 Minerals,
 Phagocytosis,
 Activate Vitamin D. 76

Small Intestine
77

Small Intestine
 Function: - Digestion and absorption
 Duodenum
 Jejunum
 Ileum: longest part
 Ileocecal sphincter:-
 Connection to large intestine.
78

Histology of Small Intestine
 Mucosa: microvilli: finger like projection: -
Increases surface area,
 Epithelium of mucosa consist Cell types-
 Absorptive
 Entero Endocrine: secretin,
Lysozyme: phagocytosis ,
 Intestinal glands
Hormone secretin
 CCK cells
Hormone – cholecystokinin (CCK) 80

Digestion in small intestine
• Mechanical digestion
• Chemical digestion:
carbohydrates: salivary amylase, pancreatic
amylase.
Protein: trypsin, chymotrypsin.
Lipid: bile emulsify lipids droplet, pancreatic
lipase,
Nucleic acid: pancreatic nucleases
81

Absorption from small intestine
82

Absorption from small intestine
• Absorption of carbohydrates
• Absorption of amino acid
• Absorption of lipid: 95 % of the lipid
• Absorption of electrolytes: most of the
electrolytes
• Vitamins : absorbed by simple diffusion
• Water: total fluid- absorb nearly 8.3 L
83
stive system

Large Intestine
• Long :- 1.5 Meter.
• Functions:-
• 1. Absorption,
• 2. Microbial Activity-Vit. K and Folic acid
• 3. Mass Movement,
• 4. Defaecation.
84

Large intestine
85

Digestion in Large intestine
• Mechanical
• chemical
• Chyme is prepared for eliminations by action
of bacteria which ferment remaining nutrients
releases hydrogen, co2, and methane gases.
• Bilirubin to simple stercobilin
• Vit B and Vit K bacterial products
86
stive system

Disorders of GI tract
• Pancreatitis
• Duodenal ulcer
87

• Gastroesophageal reflux disease, or GERD, is a
digestive disorder that affects the lower esophageal
sphincter (LES), the ring of muscle between the
esophagus and stomach. Many people, including
pregnant women, suffer from heartburn or acid
indigestion caused by GERD.
• A hernia is the abnormal exit of tissue or an organ,
such as the bowel, through the wall of the cavity in
which it normally resides. ... Groin hernias are most
common type.
• Other hernias include hiatus, incisional, and
umbilical hernias.
88

• Peritonitis is an inflammation of the peritoneum, the
tissue which present in the inner wall of the abdomen
and covers and supports most of abdominal organs.
• Peritonitis is usually caused by infection from
bacteria or fungi.
• Intestinal obstruction is significant mechanical
impairment or complete arrest of the passage of
contents through the intestine due to pathology that
causes blockage of the bowel. Symptoms include
cramping pain, vomiting, obstipation, and lack of
flatus. Diagnosis is clinical, confirmed
by abdominal x-rays.
89

• Liver Cirrhosis : - is a complication of liver
disease that involves loss of liver cells and
irreversible scarring of the liver.
• Alcohol and viral hepatitis B and C are
common causes of cirrhosis, although there are
many other causes.
• Cirrhosis can cause weakness, loss of appetite,
yellowing of the skin (jaundice), itching,
and fatigue.
• Diagnosis of cirrhosis can be suggested by
history, physical examination and
90

blood tests, and can be confirmed by liver
biopsy.
• Complications of cirrhosis include:
– Swelling of the abdomen (ascites) and in the
hip, thigh, leg, ankle, and foot
– Spontaneous bacterial peritonitis
– Bleeding,
Liver cancer
91

References:
1. A Textbook of Human Anatomy and
Physiology-II, By, Dr. S. B. Bhise and Dr. A. V.
Yadav. Nirali Prakashan, Page No.:- 2.1-2.20.
2. https://www.slideshare.net/khushbo0/huma
n-digestive-system-49903659.
3. https://www.slideshare.net/heatherelira/the
-digestive-system-ppt.
4. https://www.ccri.edu/faculty_staff/biology/j
gluck/Digestion-FINISHED.ppt.
stive system
92

Unit-II, Chapter_1-Digestive system.ppt

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