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Digestive System. Digestion the organic process by which food is converted into substances that can be absorbed into the body Google on-line dictionary.

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Presentation on theme: "Digestive System. Digestion the organic process by which food is converted into substances that can be absorbed into the body Google on-line dictionary."— Presentation transcript:

1 Digestive System

2 Digestion the organic process by which food is converted into substances that can be absorbed into the body Google on-line dictionary



5 Alimentary Tract Also known as the Digestive Tract or GI (gastrointestinal) tract This is the tube in which food is digested & broken down into energy Consists of the: Mouth Pharynx Esophagus Stomach Small intestines Large intestines Anus

6 Accessory Organs These are organs that are not within the alimentary tract but contribute to digestions Tongue Teeth Salivary glands Pancreas Liver Gallbladder

7 Alimentary Tract The tube is made up of four layers of tissue Mucosa Epithelial tissue; secretes mucous & some digestive juices Submucosa Connnective tissue; blood vessels & nerves Muscularis Circular muscles Scrosa Longitudinal muscles

8 Abdominal Cavity Peritoneum Serous membrane that lines the cavity Outer – Parietal Inner – Visceral (What other cavity has the same linings?) Mesentery – attach to posterior wall of cavity Small intestines attach Greater Omentum – attach to anterior wall Double layer; contains fat; apron



11 Types of Digestion Mechanical – physical breakdown of food Chewing – mastication Peristalsis Chemical – complex compounds broken down into simpler compounds Digestive enzymes Starch Glucose Protein Amino Acids Fat Emulsified Fat

12 Parts of the Alimentary Tract Mouth – Buccal Cavity (Oral Cavity) Accessory organs in Mouth Teeth 20 baby teeth (Deciduous) 32 Adult teeth (Permanent) Tongue Skeletal muscle Papillae – taste buds (Where are they located?) 1 st step in swallowing Salivary Glands


14 3 locations Parotid Submandibular Sublingual Secrete Saliva Continuous Food increases the production Smell increases production

15 Saliva Consists mostly of H2O Dissolves food Moistens food for swallowing Contain amylase to aid in breaking down food Ptyalin – breaks complex sugar to glucose or maltose Made from blood plasma Contain albumin, WBC, etc.

16 Esophagus Tube that connects mouth to stomach 10 inches long No digestion takes place Food is in form of bolus Peristalsis – the contraction to move food down the tube Lower esophageal sphincter (cardiac sphincter) allows food into the stomach


18 Stomach Which quadrant is it located? Which region of the abdomen? Reservoir for food Mechanical digestion Peristalsis to mix the food with gastric juice to make chyme Chemical digestion Gastric juice contains enzymes to begin food breakdown

19 Parts of the Stomach Cardiac Sphincter – controls entrance to stomach Greater curvature – outside curve Lesser curvature – inside curve Pyloric sphincter – controls exit to the duodenum Rugae – folds of the mucosa

20 Gastric secreting cells (Gastric juice) Found in the gastric pit Enteroendocrine cells (G cells) – hormone gastrin Mucous cells – secrete mucus Protects the stomach lining from acid Chief cells – secretes pepsinogen Inactive pepsin Parietal cells – secrete HCl (hydrochloric acid) Proton pump – H+ & joined with Cl- in stomach HCl converts pepsinogen to active pepsin HCl make the stomach pH 1 or 2 (what is neutral?) (acid/base) Acidity kills microorganisms Secrete intrinsic factor (to absorb what vitamin?)


22 Small Intestines

23 20 feet long 3 parts Duodenum – 12 inches Jejunum – 8 feet long Ileum – 10 – 12 feet long

24 Absorption Food is absorbed in the small intestines Chyme enters into the small intestines, many enzymes are secreted Enzymes come from the liver, pancreas, gallbladder Sucrase, Maltase, & lactase – breaks down sugar (sucrose, maltose, & lactose) Capillary network Water soluable nutrients absorb into the capillary by active transport

25 Active Transport Active transport involves the use of proteins that don't just passively facilitate the transport of substances across the cell membrane, but require the use of cellular energy(usually ATP) to actively pump substances into or out of the cell. Monosacharides Amino acids Positive ions Water – soluble vitamins

26 Absorption cont Negative ions – absorbed passive & active Water – absorbed by osmosis Certain nutrients need special substances to be absorbed B12 (intrinsic factor) Ca+ (Vitamin D)

27 Lacteals – lymph vessels in the villi Fat soluble vitamins & fats need bile salts What are the fat soluble vitamins?

28 Pancreas Feather shaped organ Exocrine & endocrine organ Secretes Pancreatic juice into the duodenum Peptidase, trypsin, & protease – breakdown protein Amylase – breakdown starch to glucose Lipase & steapsin – breakdown fat to fatty acids & glycerol Sodium bicarbonate – neutralize the chyme


30 Liver Largest organ in body makes bile Bile emulsifies fat in smaller globule to enable lipase & steapsin to break it down Stores excess sugar as glycogen Detoxifies alcohol, drugs, & toxin Prepares urea (main waste of protein metabolism) Stores what fat soluble vitamins?

31 Liver – Which quadrant is it located?

32 Large Intestines (Colon) 5 feet long Chyme enters for water absorption (80%) Also minerals & vitamins absorbed Makes fesces (undigestible material) Colonic mucus lubricates fesces for excretion Makes fesces from waste; decreased water makes formed Cecum Appendix Ascending colon Transverse colon Descending colon Rectum anus

33 Defecation Elimination of Fesces Contains Normal: 3/day – 3/week Rectum becomes distended and reflex is triggered External anal sphincter relaxes Can control the muscle Continue to ignore the reflex urge then it will lessen or goes away

34 Gas formation Flatulence Normal: 1 – 3 pints of gas /day by rectum Caused by swallowed air & breakdown of food Smell: due to bacteria in colon Gas causing foods: Beans Vegetables – broccoli & cabbage Fruit Whole grains Milk & milk products Artificial sweeteners (sorbitol)

35 Vomiting Expulsion of stomach & intestinal contents Causes Irritation Motion sickness Food poisoning Diseases Controlled by the medulla of the brain

36 Pyloric stenosis Opening of the pyloric sphincter is narrowed Sphincter is enlarged Found in infants – more common in males Symptoms - vomiting

37 Appendicitis Inflammation of the appendix Ruptured appendix can lead to peritonitis (inflammation of the abdominal peritoneal cavity) Symptoms Abdominal pain Nausea Vomiting Fever Increased WBC Know about McBurneys Point

38 Diseases of the Gallbladder All symptoms usually result after eating fatty foods Cholecystitis Inflammation of the gallbladder Pain Nausea & Vomiting indigestion Choleliathiasis Crystalized bile forming stones in the gallbladder Symptoms Pain N & V indigestion

39 Constipation Occurs when fecal matter remains in the colon too long There is too much water absorbed & the fesces becomes hardened Causes Poor bowel habits Chronic laxative use Low fiber diet Digestive system diseases

40 Diarrhea Frequent watery stools May lead to dehydration due to excess fluid loss Causes Infection Stress Diet Irritated colon Toxic substances

41 Cirrhosis Chronic destruction of liver cells Causes Hepatitis Chemical toxins Malnutrition alcoholism Symptoms N & V Liver enlargement Indigestion Jaundice hematemesis Treatment – preventing further damage NO cure

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