The Digestive System Ch. 14

Functions: mechanical and chemical breakdown of food        *absorption of nutrients Consists of alimentary canal (mouth, pharynx, esophagus, stomach, sm. intestine, large intestine, anal canal) and accessory organs

Layers of the Canal Lining 1.  Mucosa - protects tissues and carries absorption 2.  Submucosa - glands, blood vessels, nerves 3.  Muscular Layer - smooth muscle tissue, circular & longitudinal fibers, pushes food  (PERISTALSIS) 4.  Serosa (serous layer) - visceral perioneum, outer covering of the tube, lubricates surfaces (serous fluid)

Wall of the Alimentary Canal

Mixing Movements Contractions mix food with digestive juices   Peristalsis - pushes food down the tube

Anatomy of the Mouth

Anatomy of a Tooth Enamel – the outer layer of the tooth. Cementum - the bonelike tissue that forms the outer surface of the root of the tooth. Attaches the teeth to the bone. Dentin – calcareous tissue that is denser then bone

Cuspid (canine) – one point, Tearing Teeth (32) Incisors - cutting Cuspid (canine) – one point, Tearing Bicuspids – two points, tearing Molars - grinding Incisors - a narrow-edged tooth at the front of the mouth, adapted for cutting. In humans there are four incisors in each jaw. Cuspid – Having only one point. Function = holding food for tearing Bicuspid – Having two points. Molars – For grinding

Tooth Decay

ROOT CANAL

Submandibular - below jaw Sublingual - under tongue Salivary Glands Parotid - ear, cheek Submandibular - below jaw Sublingual - under tongue Serous cells produce amylase – splits starch and glycogen into disaccharides Mucous cells produce mucus – lubrication during swallowing 1. Parotid Glands produces only serous fluided 2. Submandibular Glands produces a mixture of mucus and serous fluid 3. Sublingual Glands produces a mixture of mucus and serous fluid

Pharynx (throat) nasopharynx oropharynx laryngopharynx   nasopharynx oropharynx laryngopharynx Pharynx = The pharynx permits the passage of swallowed solids and liquids into the esophagus, or gullet, and conducts air to and from the trachea, or windpipe, during respiration Nasopharynx = behind the nose Oropharynx = behind the mouth Laryngopharynx = behind the larynx Epiglottis =  but during swallowing, elevation of the hyoid bone draws the larynx upward; as a result, the epiglottis folds down to a more horizontal position, with its superior side functioning as part of the pharynx. Larynx = The larynx houses the vocal folds (vocal cords), which are essential for phonation. The vocal folds are situated just below where the tract of the pharynx splits into the trachea and the esophagus. Esophagus =takes food to the stomach

Esophagus esophageal hiatus is where it penetrates the diaphragm   cardiac sphincter at entrance to stomach

STOMACH MUSCLES:   Longitudinal, Circular, Oblique

Stomach Regions Cardiac sphincter Fundus Body Pyloric sphincter 3 sets of stomach muscles: longitudinal, oblique, circular | Greater and Lesser Curvature Four main parts of the stomach 1. Cardiac (esophageal opening, cardiac sphincter) 2. Fundic (temporary storage area, lies slightly above the cardiac region) 3. Body (central area of the stomach) 4. Pyloric (pyloric sphincter, controls emptying of the stomach into the sm. Intestine) Lining of the stomach is a mucous membrane – with small openings called gastric pits, containing gastric glands -Gastric Juice - pepsin / intrinsic factor -Chyme – paste of food molecules after its been broken down by the movement of stomach and gastric juices, it is released from the pyloric sphincter valve into the first portion of the small intestine – duodenum -Rugae – folds within the stomach, increase surface area

Stomach Lining Gastric Juices contain acids that break down food  - secreted by gastric glands   PEPSIN  - most important digestive enzyme for breaking down food Mucus prevents stomach from digesting itself  

Chyme - paste, after food has been broken down, released then into the duodenum via the pyloric sphincter valve Rugae - folds within stomach Gastric Pits contain glands to make juices  

Membrane holds it together, contains blood vessels Small Intestine   Starts at the pyloric sphincter 1.  Duodenum 2.  Jejunum 3.  Ileum *Mesentery  Membrane holds it together,  contains blood vessels

Accessory Organs Liver Gallbladder Pancreas Appendix The function of the appendix is unknown. One theory is that the appendix acts as a storehouse for good bacteria, “rebooting” the digestive system after diarrheal illnesses. Other experts believe the appendix is just a useless remnant from our evolutionary past. Surgical removal of the appendix causes no observable health problems. Bile produced by the gallbladder to the liver is secreted into the small intestine for processing of fats

The main function of the small intestine is to secrete chemicals that break down food and carry the nutrients away in the blood stream.  In one word: ABSORPTION

Greater Omentum a  "curtain-like" membrane that covers the intestines, stores fat and lays like a drape

Greater Omentum

Intestinal villi - increase surface area to absorb nutrients, connect to vessels

Large Intestine Cecum Appendix Colon (4 parts)   Cecum  Appendix Colon (4 parts)     Cecum     Ascending     Transverse      Descending      Sigmoid Rectum Anus

Function of Large Intestine Secretes mucus,  reabsorbs water, contains bacteria to aid in digestion  (intestinal flora) Mass Movements (defecation) - removes undigested food The main job is    WATER REABSORPTION...

Types 1–2 indicate constipation, with 3 and 4 being the ideal stools (especially the latter), as they are easy to defecate while not containing any excess liquid, and 5, 6 and 7 tending towards diarrhoea. Source: wiki

stomach transverse colon ascending colon descending colon cecum appendix sigmoid colon rectum

Disorders of the Digestive System   GERD Gastroesophageal reflux disease

Dysentery or Diarrhea

Crampy abdominal pain Fatigue Loss of appetite Pain with passing stool (tenesmus); bloody stool Persistent, watery diarrhea Weight loss Constipation

IBS - Irritable Bowel Syndrome The muscles in the bowel wall may contract too forcefully or too weakly, too slowly or rapidly at certain times.

STOMACH ULCERS

Lactose Intolerance    Inability to digest milk, can cause stomach upset

Hernia intestines poke through abdominal muscles

When people with celiac disease eat foods or use products containing gluten, their immune system responds by damaging or destroying villi   Without healthy villi, a person becomes malnourished, no matter how much food one eats.

Gastric Bypass Surgery

Colon Cancer Colonoscopy is a screening technique to detect cancer. See Katie Couric's Colonoscopy

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