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Digestive System - Anatomy and Physiology - Lecture Slides |, Study notes of Physiology

College of Central Florida Physiology

Chapter 24 Material Type: Notes; Class: Anatomy & Physiology; Subject: Biology / Biological Sciences; University: Central Florida Community College; Term: Forever 1989;

Typology: Study notes

2009/2010

Uploaded on 11/13/2010

cuteypatutty 🇺🇸

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Slide 1

The Digestive System

Slide 2

Organs of the Digestive System

• GITract=gastrointestinal tract=Alimentary

canal 512

• Accessory digestive organs

Slide 3

Functions of GI tract

• 1. Ingestion

• 2. Secretion

• 3. Mixing and propulsion

• 4. Digestion

• Chemical- Hydrolysis of large biological molecules

• 5. Absorption- from GIT

• 6. Defecation- passage of stool

Partial preview of the text

Download Digestive System - Anatomy and Physiology - Lecture Slides | and more Study notes Physiology in PDF only on Docsity!

The Digestive System

Slide 2

Organs of the Digestive System

• GITract=gastrointestinal tract=Alimentary

canal 512

• Accessory digestive organs

Slide 3

Functions of GI tract

1. Ingestion
1. Secretion
1. Mixing and propulsion
1. Digestion
- Chemical- Hydrolysis of large biological molecules
1. Absorption- from GIT
1. Defecation- passage of stool

Layers of GIT

• Mucosa= inner lining 513

Composed of » 1. Epithelium- » 2. Lamina propria- 3. Muscularis mucosa

Slide 5

Layers of GIT continued

1. Submucosa 513
1. Muscularis
- Skeletal muscle sphincter contain skeletal muscle- mouth, pharynx, part of esophagus and anal
- Smooth muscle- Involuntary-
- Myenteric plexus lies between smooth muscle layers
1. Serosa

Slide 6

Neural innervation of GIT

• Enteric Nervous System (ENS) 514

1. Myenteric Plexus
1. Submucosal plexus
Interneurons coordinate
Sensory neurons include

Peritoneum continued

1. Lesser omentum
1. mesentery »
1. Mesocolon » Binds large intestine to posterior abdomenal wall;

Slide 11

Mouth

• Oral cavity is formed by

• Lips are attached to gums by lingual

frenulum

Vestibule

• Fauces= opening between

oral cavity and throat

Slide 12

Mouth continued

Hard palate
- Anterior portion
Soft palate
- Posterior portion
Uvula
- Hangs from free border of soft palate
- Drawn superiorly during swallowing to prevent swallowed foods from entering nasal cavity
Tonsils

Salivary Glands

• Release saliva

• Minor glands

Mucous membranes of mouth and tongue

Slide 14

Major Salivary Glands

• 1. Parotid 518

• 2. Submandibular

Fluid thickened with mucous + amylase

• 3. Sublingual

Mostly mucus
Each gland is accompanied by a duct or ducts that

open into the mouth

Slide 15

Functions of Saliva

• 99.5% water-

• Buffer acidic foods

• Cl ions activate amylase-

• Mucus

IgA prevents attachment of microbes

Permanent teeth

Erupt between
32 total
Incisors- chisel shaped-
Cuspids (canines)-
Bicuspids (first & second premolar)-
First, second, third molars-

Slide 20 Mechanical and Chemical

Digestion in Mouth

• Mechanical=chewing/mixing with saliva to

form a bolus (soft mass)

• Chemical

Salivary amylase-
Lingual lipase- » Secreted by lingual glands

Slide 21

Pharynx

• Muscular tube that propels food

Esophagus

Posterior to trachea
Extends from inferior end of pharynx to stomach
- Regulate movement of food into esophagus and stomach
4 layers
- Mucosa,
- Submucosa,
- Muscularis
- Adventitia= outer layer

Slide 23

Deglutition

Process that moves food from mouth to stomach. Three stages: 521 - 1. Voluntary stage - 2. Pharyngeal stage ( involuntary) - Oropharynx to esophagus » Epiglottis » Uvula - 3. Esophageal stage - Esophagus to stomach » Peristaltic waves- alternating circular and longitudinal muscle contractions

Slide 24

The Stomach

• Digestion of starch

• Digestion of proteins and triglycerides

• Bolus

• Some substances

absorbed

Chemical Digestion in the Stomach

1. Parietal cells secrete acid (HCl) and intrinsic

factor (B12 absorption)

2. Mucous cells secrete mucus

3. G cells secrete gastrin-

3. Chief cells secrete pepsinogen and gastric lipase

Pepsin breaks proteins
Gastric lipase splits triglycerides

Slide 29 Why doesn’t gastric juice digest the

stomach?

• 1. Pepsin is secreted in an inactive form

called pepsinogen

• 2. Lining of stomach is protected

Slide 30

The Pancreas

• Between stomach and duodenum 526

• ~6 inches long

• Connected to duodenum by two ducts

Pancreatic duct unites with common bile duct
Accessory duct empties into duodenum

• Ducts carry

Histology of the Pancreas

• Exocrine portion:

99% of clusters of glandular cells (called acini)

• Endocrine portion

1% of clusters of glandular cells (called islets of

Langerhans)

» Secrete hormones

Slide 32

Pancreatic Juice

Mostly water
Bicarbonate- buffers gastric acid
Pancreatic enzymes
- 1. Protein digesting (secreted in inactive form) » Trypsin, chymotrypsin, carboxypeptidase and elastase are
- 1. Triglyceride digesting^ active forms
- 1. Starch digesting
- 1. Nucleic acid digesting » Ribonuclease and deoxyribonuclease

Slide 33

The Liver and Gallbladder

• Heaviest gland in the body

• Located

• Gallbladder is pear shaped sac

Flow of Bile

• Bile is secreted by hepatocytes

Passed through a series of canals

• Ducts merge to form right and left hepatic

ducts

Merge to form common hepatic duct
- Unites with cystic duct from gallbladder 526, 527

Merges with pancreatic duct to duodenum

Slide 38 Blood supply of the Liver

Portal triad (located at corners of lobules)
- Composed of hepatic artery and hepatic portal vein and bile duct
- Hepatic artery
- Hepatic portal vein contains deoxygenated blood
To central vein
To hepatic vein
To inferior vena cava
To right atrium

Slide 39

Bile

• Yellow, brown to green in color

• Contains water, bile salts and pigments,

cholesterol, lecithin and several ions.

Biliruben (breakdown of RBC’s)
Bile salts

• Between meals

bile flows into gall bladder

Functions of hepatocytes

Release or storage
• Lipid metabolismDeaminate
Convert ammonia to urea
• Synthesis of plasma proteinsDetoxification
• Destroy worn out RBCExcretion of biliruben’s
Synthesis of
Storage of
• Phagocytosis of bacteria and worn out cellsActivation of vitamin D

Slide 41

Small Intestine

• Major site of

• Consists of

• Contains circular folds that

increase surface area for absorption

• Has villi and microvilli that

increase surface area for absorption

Slide 42

Anatomy of Small intestine

• 10 feet long

• 3 Regions:

Duodenum
Jejunum
Ileum 530

Brush border Enzymes

Carbohydrate digesting:
Protein digesting:
- Aminopeptidases and dipeptidases
Nucleotide digesting:
- nucleosidases and
- phosphatases

Slide 47 Mechanical digestion in Small

intestine

• Two types of movements:

1. Segmentations- localized, mixing contractions
1. Peristalsis (migrating motility complex)
- pushes chyme forward.
- Takes~ 3 hours to reach end of ileum

Slide 48 Chemical Digestion in Small

intestine

• 1. Carbohydrates

Amylase from pancreatic juice
- brush border enzymes:
  - Alpha dextrinase
  - Sucrase
  - Lactase
  - Maltase
****only monosaccharides can be absorbed

Slide 49 Chemical Digestion in Small

Intestine

• 2. Proteins:

Enzymes in pancreatic juice
- brush border enzymes:
  - Aminopeptidase
  - Dipeptidases

• 3. Lipids:

Pancreatic Lipase +
emulsification from bile salts » Large lipid globule

Slide 50 Chemical Digestion in Small

intestine continued

• 4. Nucleic Acids

Pancreatic juice
- brush border enzymes:
Nucleosidases and phosphastases

Slide 51

Absorption in the Small intestine

• Each of the following can be absorbed

across small intestinal epithelial cells:

1. Monosaccharides
1. Single amino acids, dipeptides, and tripeptides
1. Fatty acids, glycerol and monoglycerides
1. Nucleotides

Anatomy of the Large Intestine

Extends from ileum to anus » Regions= cecum colon rectum anus
1. ileocecal valve
1. cecum
1. ascending colon
1. transverse colon
1. descending colon
1. sigmoid colon
1. rectum
1. anus

Slide 56

Histology of the Large Intestine

• Four layers: 536

1. Mucosa
- Aborptive cells
- goblet cells
1. submucosa
1. Muscularis
1. serosa

Slide 57 Puckered appearance of Large

intestine

• Teniae coli= longitudinal bands of smooth

muscle

• Haustra= series of pouches

Slide 58 Mechanical Digestion in Large

Intestine

• 1. Haustral churning- when distended,

contents are squeezed to next haustra

• 2. Peristalsis-

• 3. Mass peristalsis- quickly drives

contents of colon into rectum

Slide 59 Chemical Digestion in Large

Intestine

• Achieved by the action of bacteria

1. Ferment any remaining carbohydrates and release gases
1. convert any remaining amino acids into simpler substances (indole, skatole and H2S)
1. Decompose biliruben
1. Synthesize

Digestive System - Anatomy and Physiology - Lecture Slides |, Study notes of Physiology

Related documents

Partial preview of the text

Download Digestive System - Anatomy and Physiology - Lecture Slides | and more Study notes Physiology in PDF only on Docsity!

The Digestive System

Slide 2

Organs of the Digestive System

• GITract=gastrointestinal tract=Alimentary

canal 512

• Accessory digestive organs

Slide 3

Functions of GI tract

Layers of GIT

• Mucosa= inner lining 513

Slide 5

Layers of GIT continued

Slide 6

Neural innervation of GIT

• Enteric Nervous System (ENS) 514

Peritoneum continued

Slide 11

Mouth

• Oral cavity is formed by

• Lips are attached to gums by lingual

frenulum

• Fauces= opening between

Slide 12

Mouth continued

Salivary Glands

• Release saliva

• Minor glands

Slide 14

Major Salivary Glands

• 1. Parotid 518

• 2. Submandibular

• 3. Sublingual

open into the mouth

Slide 15

Functions of Saliva

• 99.5% water-

• Buffer acidic foods

• Cl ions activate amylase-

• Mucus

IgA prevents attachment of microbes

Permanent teeth

Slide 20 Mechanical and Chemical

Digestion in Mouth

• Mechanical=chewing/mixing with saliva to

form a bolus (soft mass)

• Chemical

Slide 21

Pharynx

• Muscular tube that propels food

Esophagus

Slide 23

Deglutition

Slide 24

The Stomach

• Digestion of starch

• Digestion of proteins and triglycerides

• Bolus

• Some substances

Chemical Digestion in the Stomach

1. Parietal cells secrete acid (HCl) and intrinsic

factor (B12 absorption)

2. Mucous cells secrete mucus

3. G cells secrete gastrin-

3. Chief cells secrete pepsinogen and gastric lipase

Slide 29 Why doesn’t gastric juice digest the

stomach?

• 1. Pepsin is secreted in an inactive form

called pepsinogen

• 2. Lining of stomach is protected

Slide 30

The Pancreas

• Between stomach and duodenum 526

• ~6 inches long

• Connected to duodenum by two ducts

• Ducts carry

Histology of the Pancreas