Post on 17-Jan-2018
description
transcript
The Digestive SystemHealth Science 1
Silver
What is Digestion The process of changing complex solids
foods into simpler soluble forms which can be absorbed by cells.
Enzyme – chemical substance that can promote reactions in living things
Terminology Alimentary canal
› Also known as the GI (gastrointestinal tract)
› Begins with the mouth and ends with the anus
› Include Mouth Pharynx Esophagus Stomach Small intestines Large intestine
• Accessory Organs• Teeth• Tongue• Salivary glands• Pancreas• Liver• Gallbladder
• Connected to the GI tract by series of ducts
• Aid in chemical breakdown and absorption of food.
Lining the Digestive System Peritoneum
› Double layered serous membrane that lines the abdominal cavity
Digestive System Functions Physical Breakdown of food Chemical digestion of food into the end
products of fat, carbohydrates and protein
Absorb nutrients into blood capillaries of the small intestines
Eliminate waste products of digestion
6 Activities of Digestion (in order)
1 – Ingestion› Getting food into the body› Mouth, teeth, lips and tongue
2 – Mechanical Breakdown › Smaller pieces of food (chewing, churning in
stomach, churning by muscular contraction in small intestine)
3 – Propulsion› Initiated by swallowing (pharynx)› Peristalsis (symmetrical contraction of muscles
that moves food along the GI tract
6 Activities of Digestion (in order)
4 – Chemical breakdown› Commonly called “digestion”› Enzymes breakdown food
5 – Absorption› Movement of small molecules from small
intestine into the blood to be carried to other parts of the body
6 – Defecation› Expulsion of the food that was not absorbed
through the anus.
Mouth (oral cavity) Assist in
› Ingestion (food in mouth)› Mechanical breakdown
(chewing)- also called mastication
› Chemical breakdown (enzymes in saliva)
› PTYALIN- converts starches into simple sugars – under control of the nervous system
› Propulsion (pushing food back to pharynx for swallowing)
Lips – grab food and pull into mouth
Tongue – contain papillae that help to grip food better (sense of taste from taste buds)
Palate (roof of mouth)› hard and soft
Uvula› Keeps food out of nasal
cavity when swallowing
Mouth cont… Teeth and Gums
› Digestive enzymes help to chemically break down food once chewing begins
› Mastication – process of chewing (mechanical digestion)
Children have 20 deciduous (temporary)› Start to appear
around 6 months› Usually all are
visible by 2 yrs of age
Permanent teeth begin to form around 6 years of age in the jawbones
32 total (16 in mandible and 16 in maxilla)
As these grow, the deciduous teeth are pushed out
The wisdom teeth are generally the last to appear, usually late teens to early twenties.
Incisors Canine Premolars molars
2123 System – 2 incisors, 1 canine, 2premolars, 3 molars
Salivary glands Secrete saliva into the mouth via connecting
ducts. Contains mucus, antibodies, and enzymes to help moisten food and protect the mouth from bacterial infection.
Parotid (largest)- under skin, just below and in front of the ears.
Submandibular – medial side of the lower back part of the mandible.
Sublingual – under each side of the tongue.
Pharynx Food at this point is called a BOLUS Passage way for food and air Propulsion of food by peristalsis
Most commonly considered part of the respiratory system
Epiglottis at end that guides food to the esophagus when swallowing – Remember ---- Air goes to the trachea
Swallowing = deglutination
Esophagus Flexible muscular tube that connects
the pharynx to the stomach. About 10 inches long Travels through the diaphragm
Food is propelled through by waves of peristalsis (muscular contraction to push food downward)
Stomach Located in upper more left part of abdominal cavity
filled with gastric juices. Acidic in nature – protected by mucus membrane
› Pepsin- breaks down protein› Hydrochloric acid destroys unwanted bacteria
Reservoir where food is broken down both mechanically and chemically.
Contains cardiac sphincter (top)- circular muscular layer that controls the passage of food into the stomach.
Pyloric sphincter (bottom) – valve that regulates the entrance of food into the duodenum of small intestine.
Stomach cont…. Rugae – mucous coated lining inside the
stomach (folds of tissue)
Peristalsis continues in the stomach
The bolus of food now is known as CHYME – semi liquid, creamy substance
Chyme leaves the stomach through the pyloric sphincter
Parts of the stomach Fundus- upper part Body – middle part Pyloric region – lower end
Small Intestines Gets its name from its diameter….much smaller
than the large intestine even though it is longer
Site of most of the chemical breakdown of food. Food is broken down into usable substances which can now be used by the tissue in the body.
Site for Absorption – in small intestine, digested food passes into the bloodstream and on to body cells. Undigestible parts pass on to the large intestine.
3 segments of small intestines
Duodenum – 1st segment (curves around the pancreas.
Is about 12 inches long
Jejunum- 2nd section, about 8 foot long
Ileum- final portion, 10 to 12 feet in length Chemical digestion, absorption, and
propulsion by peristalsis occur in all three segments of the small intestine.
Pancreas Located behind the stomach Secretes digestive enzyme (pancreatic
juice) into the duodenum. It travels through the pancreatic duct and common bile ducts to get to small intestine.
Enzymes here help digest proteins and fats.
It also makes the hormone insulin (endocrine system)
Liver Largest organ in body Located below the diaphragm, RUQ Connected to gallbladder and small intestine by
ducts Produces and stores glucose in the form of
glycogen Detoxify alcohol, drugs and other harmful
substances Manufactures blood proteins Manufactures bile Stores vitamins A, D and B complex
Gallbladder Small green organ, inferior surface of the liver Stores and concentrates bile until it is needed
by the body Releases bile to help break down fatty foods
via the common bile duct Fat is then stored in lacteals in the
intestinal wall until needed by the body
You can live without your gallbladder, but you have to keep your liver
Large Intestine Larger diameter than small intestine but shorter in
length Approximately 2 inches in diameter Major segments – cecum, colon, rectum and anal
canal (anus) Nutrients and water not absorbed in small
intestines are absorbed here. Contains E. Coli (bacteria) Main function is propulsion and elimination of
waste products not absorbed in the small intestines In the colon…Chyme becomes FECES
Parts of the large intestine Cecum – first part in lower right
portion. Appendix – small fingerlike projection
that extends from the cecum (not needed). It does contain lymphocytes.
Colon- 4 segments- Ascending colon, transverse colon, descending colon, and sigmoid colon
Rectum - last portion of the colon Anus - external opening
Defacation = Elimination of feces Flatulence = gas Bacteria causes the
odor
GERD – Gastroesophageal Reflux Disease
Heartburn or acid reflux symptoms include chronic cough and chest pain and burning. Knowing your triggers, such as certain foods, medications, obesity, or even stress, can help prevent heartburn. Heartburn treatment may include medications, home remedies, or diet changes.
http://www.webmd.com/heartburn-gerd/ss/slideshow-heartburn-overview
Gastroenteritis Gastroenteritis is inflammation of the stomach and
intestines, which leads to diarrhea and vomiting. Gastroenteritis is most often due to a bacterial or viral infection. Gastroenteritis that results from a virus is called viral gastroenteritis. Many different viruses cause gastroenteritis, including some rotaviruses, noroviruses, and adenoviruses. Viral gastroenteritis is contagious. Bacterial gastroenteritis is often caused by infection with E. coli and salmonella. Other causes of gastroenteritis include parasite infection, exposure to harmful chemicals in seafood or water, use of certain medications, and irritation from particular foods.
http://www.webmd.com/children/ss/nausea-vomiting-remedies-treatment
Peptic ulcer http://www.webmd.com/digestive-disor
ders/tc/peptic-ulcer-disease-topic-overview
Appendicitis Appendix becomes inflamed
If it ruptures, bacteria will spread to peritoneal cavity causing a very dangerous infection.
Symptoms - fever, acute pain in LRQ
RX- surgical removal & antibiotics
Hepatitis Inflammation of the liver Types A, B, C
http://www.webmd.com/hepatitis/ss/slideshow-hepatitis-overview
CirrhosisCirrhosis is a slowly progressing disease in which healthy liver tissue is replaced with scar tissue, eventually preventing the liver from functioning properly. The scar tissue blocks the flow of blood through the liver and slows the processing of nutrients, hormones, drugs, and naturally produced toxins. It also slows the production of proteins and other substances made by the liver.
JAUNDICE – yellow discoloration of the skin and sclera of the eyes.
Cholecystitis
Cholecystitis is inflammation of the gallbladder, a small organ near the liver that plays a part in digesting food. Normally, fluid called bile passes out of the gallbladder on its way to the small intestine. If the flow of bile is blocked, it builds up inside the gallbladder, causing swelling, pain, and possible infection.
Commonly caused by CHOLELITHIASIS
Cholelythiasis A gallstone stuck in the cystic duct , a
tube that carries bile from the gallbladder, is most often the cause of sudden (acute) cholecystitis. The gallstone blocks fluid from passing out of the gallbladder. This results in an irritated and swollen gallbladder. Infection or trauma, such as an injury from a car accident, can also cause cholecystitis.
Diarrhea Diarrhea is a loose, watery bowel movement
and is not usually a serious problem in the U.S. It can occur due to illness, intestinal problems, food poisoning, and many others factors. It usually goes away on its own, but you should drink plenty of fluids and can take over-the-counter medications to help ease the discomfort. For prolonged cases of diarrhea, medical attention is recommended.
http://www.webmd.com/digestive-disorders/video/drossman-diarrhea-overview
Constipation Constipation is a common but painful
condition that occurs when bowel movements become infrequent or difficult. It can be caused by nutritional deficiencies, stress, pregnancy, cancer, depression, and more. The best way to prevent constipation is eating a healthy diet, exercising, and drinking plenty of water. Laxatives can help relieve constipation.
http://www.webmd.com/digestive-disorders/ss/slideshow-constipation-facts-10
Irritable bowel syndrome Irritable bowel syndrome or IBS affects
mostly women. Causes are unknown. IBS symptoms include diarrhea, constipation, and abdominal cramps. IBS treatments include diet and lifestyle changes and medications.
http://www.webmd.com/ibs/ss/slideshow-ibs-overview
Anorexia Nervosa Anorexia
› Intense fear of gaining weight› Restrict food intake, especially those with
fat content› Weight is 85% less than expected body
weight› Over exercising› Avoiding food altogether, or only allowing
minimal low calorie intake.
Physical Symptoms Common physical signs of malnutrition from
anorexia include: A low body weight. Constipation and slow emptying of the stomach. Thinning hair, dry skin, and brittle nails. Shrunken breasts. Stopping or never getting a monthly menstrual
period. Feeling cold, with a lower-than-normal body
temperature. Low blood pressure.
Treatment All people with anorexia need
treatment. In most cases, this involves seeing a doctor and having regular counseling sessions. A hospital stay is needed for those who are seriously underweight or who have severe medical problems. The goals of treatment are to restore a healthy weight and healthy eating habits.