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Chapter 14 Accessory Digestive Organs Accessory Digestive Organs Salivary glands Teeth Pancreas Liver Gall Bladder

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Page 1: Accessory Digestive Organs Chapter 14 Accessory Digestive Organs Salivary glands Teeth Pancreas Liver Gall Bladder

Chapter 14Accessory Digestive OrgansAccessory Digestive Organs

• Salivary glands

• Teeth

• Pancreas

• Liver

• Gall Bladder

Page 2: Accessory Digestive Organs Chapter 14 Accessory Digestive Organs Salivary glands Teeth Pancreas Liver Gall Bladder

1. Salivary Glands1. Salivary Glands 3 glands

- Parotid glands – located anterior to ears

- Submandibular glands

- Sublingual glands

Saliva

- Mostly water

- Mixture of mucus and serous fluids

- Helps to form a food bolus

- Salivary amylase begins starch digestion

- Dissolves chemicals so they can be tasted

Page 3: Accessory Digestive Organs Chapter 14 Accessory Digestive Organs Salivary glands Teeth Pancreas Liver Gall Bladder

2. Teeth - 2. Teeth - Masticates (chews) food- Deciduous (baby or milk) teeth; 20 teeth by age two

- Permanent teeth; between the ages of 6 to 12; full set = 32 teeth

Page 4: Accessory Digestive Organs Chapter 14 Accessory Digestive Organs Salivary glands Teeth Pancreas Liver Gall Bladder

Regions of a ToothRegions of a ToothCrown – exposed part

Outer enamel

Dentin

Pulp cavity

Neck

Region in contact with gum

Connects crown to root

Root• Periodontal membrane attached to bone• Root canal carrying blood

vessels and nerves

Page 5: Accessory Digestive Organs Chapter 14 Accessory Digestive Organs Salivary glands Teeth Pancreas Liver Gall Bladder

3. Pancreas3. Pancreas Makes digestive enzymes

that break down all types of food

Enzymes secreted into duodenum

Alkaline fluid added with enzymes neutralizes acidic chyme

Endocrine products of pancreas

- Insulin

- Glucagons

Page 6: Accessory Digestive Organs Chapter 14 Accessory Digestive Organs Salivary glands Teeth Pancreas Liver Gall Bladder

4. Liver & Bile4. Liver & Bile Largest gland; right side under the diaphragm

4 lobes suspended by falciform ligament

Connected to the gall bladder via common hepatic duct

Bile made by liver cells

Bile composition

- Bile salts

- Bile pigment (bilirubin - breakdown of hemoglobin)

- Cholesterol

- Phospholipids

- Electrolytes

Page 7: Accessory Digestive Organs Chapter 14 Accessory Digestive Organs Salivary glands Teeth Pancreas Liver Gall Bladder

5. Gall Bladder5. Gall Bladder Sac found in

depression of liver

Stores bile from the liver by way of the cystic duct

Bile is introduced into the duodenum in the presence of fatty food

Gallstones can cause blockages

Page 8: Accessory Digestive Organs Chapter 14 Accessory Digestive Organs Salivary glands Teeth Pancreas Liver Gall Bladder

Processes of the Digestive SystemProcesses of the Digestive System

1. Ingestion – into mouth

2. Propulsion – moving foods

3. Mechanical digestion - Mixing food

a. mouth & tongue b. stomach churning c. segmentation in sm. int.

4. Chemical Digestion - Enzymes break down food

5. Absorption - products into the blood or lymph

6. Defecation - Elimination of indigestible substances as feces

Page 9: Accessory Digestive Organs Chapter 14 Accessory Digestive Organs Salivary glands Teeth Pancreas Liver Gall Bladder

Control of Digestive ActivityControl of Digestive Activity

Controlled by reflexes of parasympathetic division

Chemical & mechanical receptors are located in organ walls that trigger reflexes

Stimuli include:

- Stretch of the organ

- pH of the contents

- Presence of breakdown products

Reflexes include:

- Activation or inhibition of glandular secretions

- Smooth muscle activity

Page 10: Accessory Digestive Organs Chapter 14 Accessory Digestive Organs Salivary glands Teeth Pancreas Liver Gall Bladder

Deglutition (Swallowing)Deglutition (Swallowing)A. Buccal phase – Voluntary, in mouth, bolus made,

tongue pushes into pharynx

B. Pharyngeal-esophageal phase - Involuntary, Tongue blocks mouth, Soft palate (uvula) blocks the nasopharynx, Epiglottis blocks the larynx, Peristalsis moves the bolus, cardioesophageal sphincter opens with pressure

Page 11: Accessory Digestive Organs Chapter 14 Accessory Digestive Organs Salivary glands Teeth Pancreas Liver Gall Bladder

Food Breakdown in the StomachFood Breakdown in the Stomach Gastric juice - regulated by

nerves & hormones

Presence of food or falling pH = release of gastrin

Gastrin causes stomach glands to produce protein-digesting enzymes

Hydrocholoric acid makes stomach very acidic

- Activates pepsinogen to pepsin for protein digestion

- Provides a hostile environment for microorganisms

Page 12: Accessory Digestive Organs Chapter 14 Accessory Digestive Organs Salivary glands Teeth Pancreas Liver Gall Bladder

Digestion and AbsorptionDigestion and Absorption Protein digestion enzymes

- Pepsin – an active protein digesting enzyme

- Rennin – works on digesting milk protein

The only absorption that occurs in the stomach is of alcohol and aspirin

Stomach empties in 4-6 hrs.

Page 13: Accessory Digestive Organs Chapter 14 Accessory Digestive Organs Salivary glands Teeth Pancreas Liver Gall Bladder

Digestion in the Small IntestineDigestion in the Small Intestine Enzymes from the brush border

- Break double sugars into simple sugars

- Complete some protein digestion

Pancreatic enzymes - Help complete digestion of starch (pancreatic

amylase)

- Carry out about half of all protein digestion (trypsin, etc.)

- Responsible for fat digestion (lipase)

- Digest nucleic acids (nucleases)

- Alkaline content neutralizes acidic chyme

Page 14: Accessory Digestive Organs Chapter 14 Accessory Digestive Organs Salivary glands Teeth Pancreas Liver Gall Bladder

Stimulation of Pancreatic JuiceStimulation of Pancreatic Juice

Vagus nerve

Local hormones

- Secretin

- Cholecystokinin

Page 15: Accessory Digestive Organs Chapter 14 Accessory Digestive Organs Salivary glands Teeth Pancreas Liver Gall Bladder

Absorption in the Small IntestineAbsorption in the Small Intestine

Water is absorbed along the length of the small intestine

End products of digestion

- Most substances are absorbed by active transport through cell membranes

- Lipids are absorbed by diffusion

Substances are transported to the liver by the hepatic portal vein or lymph

Page 16: Accessory Digestive Organs Chapter 14 Accessory Digestive Organs Salivary glands Teeth Pancreas Liver Gall Bladder

Absorption in the Large IntestineAbsorption in the Large Intestine

No digestive enzymes are produced

Resident bacteria digest remaining nutrients

- Produce some vitamin K and B

- Release gases

Water and vitamins K and B are absorbed

Remaining materials are eliminated via feces

Page 17: Accessory Digestive Organs Chapter 14 Accessory Digestive Organs Salivary glands Teeth Pancreas Liver Gall Bladder

Propulsion in the Large IntestinePropulsion in the Large Intestine

Sluggish peristalsis

Mass movements

- Slow, powerful movements

- Occur three to four times per day

Presence of feces in the rectum causes a defecation reflex

- Internal anal sphincter is relaxed

- Defecation occurs with relaxation of the voluntary (external) anal sphincter