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Chapter 14 Accessory Digestive Organs

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Presentation on theme: "Chapter 14 Accessory Digestive Organs"— Presentation transcript:

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

2 1. 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

3 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

4 Regions of a Tooth Crown – 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

5 3. 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

6 4. 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

7 5. 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

8 Processes of the Digestive System
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

9 Control 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

10 Deglutition (Swallowing)
Buccal phase – Voluntary, in mouth, bolus made, tongue pushes into pharynx 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

11 Food 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

12 Digestion 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.

13 Digestion 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

14 Stimulation of Pancreatic Juice
Vagus nerve Local hormones Secretin Cholecystokinin

15 Absorption 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

16 Absorption 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

17 Propulsion 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

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