Adv.MedT.Ch5.DigestiveSys.Review

• Digestive or gastrointestinal tract
• --begins with the mouth (where food enters)
• --ends with the anus (where solid waste material leaves the body)

1) ingestion (complex food taken into the mouth is ingested)

2) digestion (food broken down is digested, mechanically & chemically, as it travels through the gastrointestinal tract.)

• 3) absorption (digested food passes through the lining cells or epithelium of the small intestine and into the bloodstream.)
• -Digestive enzymes speed up the chemical reactions and aid the breakdown (digestion) of complex nutrients.
• --Complex proteins are digested to simpler amino acids
• ---complicated sugars are reduced to simple sugars, such as glucose.
• ----large fat or lipid molecules are broken down to simpler substances such as fatty acids and triglycerides (three parts fatty acids and one part glycerol).

4) elimination (solid waste materials that cannot be absorbed into the bloodstream is eliminated.)

form the walls of the oval-shaped oral cavity

surround the opening of the cavity

-lies anterior to the soft palate and is supported by the upper jawbone (maxilla).

-the anterior portion of the roof of the mouth

is the muscular fleshy part between the mouth and the throat.

are irregular ridges in the mucous membrane covering the anterior portion of the hard palate.

-a small soft tissue projection, hangs from the soft palate.

-it aids production of sounds and speech.

-extends across the floor of the oral cavity

-muscles attach to the lower jawbone.

chewing

swallowing

-small raised areas on the tongue

-contain taste buds that are sensitive to the chemical nature of foods and allow discrimination of different tastes as food moves across the tongue.

fleshy tissue surrounding the sockets of the teeth

surface (labi/o means lip), for incisor and canine teeth, is nearest the lips.

surface (bucc/o means cheek), for premoloar and molar teeth, lies adjacent to the cheek.

**Dentists refer to both the labial & buccal surfaces of a tooth as the facial surface.

surface (lingu/o means tongue)

surface of a tooth lies nearer to the median line

surface lies farther from the medial line.

surface (occlusion means closing) that comes in contact with a corresponding tooth in the opposing arch.

• -consists of a crown, shows above the gum line.
• -a root, lies within the bony tooth socket.
• -enamel, outermost protective layer of the crown. (protech the tooth)
• -dentin, the main substance of the tooth.
• -cementum, covers, protects, and supports the dentin in the root.
• -periodontal membrane, surrounds the cementum and holds the tooth in place in the tooth socket.
• -pulp, lies underneath the dentin. this soft and delicate tissue fills the center of the tooth.
• ------> the pulp canal (also called the root canal), is the blood vessels, nerve endings, connective tissue, and lymphatic vessels.

• *exocrine glands produce saliva, which lubricates the mouth.
• *Saliva, contains important digestive enzymes as well as healing growth factors, such as cytokines.

• -three pairs of salivary glands that releases saliva:
• 1) parotid gland
• 2) submandibular gland
• 3) sublingual gland

-throat, a muscular tubes, 5" long, lined with a mucous membrane

-is 9-10" muscular tube extending from the pharynx to the stomach where peristalsis take place in pushing food down to the stomach.

-is the involuntary, progressive, rhythmic contraction of muscles in the wall of the esophagus (and other gastrointestinal organs) propelling a bolus (mass of food) down toward the stomach.

mass of food

• 1) fundus (upper portion)
• 2) body (middle section)
• 3) antrum (lower portion)

-rings of muscle control the openings into and leading out of the stomach.

-it prevents food from regurgitating (flowing backward from the normal direction).

relaxes and contracts to move food from the esophagus into the stomach.

allows food to leave the stomach when it is ready.

-folds in the mucous membrane (mucosa) linging the stomach

-contain digestive glands that produce the enzyme pepsin (to begin digestion of proteins) and hydrochloric acid.

-extends for 20ft from the pyloric sphincter to the first part of the large intestine.

• **three sections of the SI:
• 1) duodenum (1foot long, receives food from the stomach as well as bile from the liver and the gallbladder & pancreatic juice from the pancreas. Enzymes + bile help digest food before it passes into the jejunum)

2) jejunum (8ft long)

3) ileum (11ft long, attach to 1st part of the large intestine)

-millions of tiny microscopic projections, line in the walls of the small intestine.

-consists of tiny capillaries (microscopic blood vessels) which absorb the digested nutrients into the bloodstream and lymph vessels.

-extends from the end of the ileum to the anus.

• **three sections of the LI:
• 1) cecum, is a pouch on the right side that connects to the ileum at the ileocecal valve (sphincter); the appendix hangs from the cecum.

• 2) colon, 5ft long
• ---ascending colon, extends from the cecum to the undersurface of the liver.
• ---descending colon
• ---sigmoid colon, shape like an S, leads to the rectum

3) rectum, terminates in the lower opening of the gastrointestinal tract, the anus.

is the expulsion or passage of feces from the body through the anus.

-located in the right upper quadrant (RUQ) of the abdomen

-manufactures a thick, orange-black, sometimes greenish, fluid called bile.

-secretes bile; stores sugar, iron, and vitamins; produces blood proteins; and destroys worn-out red blood cells.

• -greenish fluid
• -contains cholesterol (fatty substance), bile acids, and several bile pigments (eg. bilirubin), bile salts.
• -digestive juice made in the liver and stored in the gallbladder.
• -it breaks up (emulsifies) large fat globules.
• -originally was called gall.

-pigment released by the liver in bile.

• -is produces from the breakdown of hemoglobin during normal red blood cell destruction.
• -travels via the bloodstream to the liver, where it is conjugated or converted into a water-soluble form.
• -conjugated bilirubin is then added to bile and enters the intestine (duodenum).
• -bacteria in the colon degrade bilirubin into a variety of pigments that give feces a brownish color.
• -bilirubin and bile leave the body in feces.

-yellow discoloration of the skin, whites of the eyes, and mucous membranes.

-due to excessive bilirubin remains in the bloodstream when the bile duct is blocked or the liver is damaged and unable to excrete bilirubin into bile.

-normally due to hemolysis (destruction of the red blood cell).

• -a pear-shaped sac under the liver
• - stores and concentrates the bile for later use.

**after meals, in response to the presence of food in the stomach and duodenum, the gallbladder contracts, forcing the bile out the cystic duct into the common bile duct.

• -organ under the stomach
• -produces insulin (for transport of sugar into cells) and enzymes (for digestion of foods).

-secretes pancreatic juices (enzymes) that are released into the pancreatic duct, which joins with the common bile duct just as it enters the duodenum.

• -first part of the small intestine.
• -receives a mixture of bile and pancreatic juices.

-physical process of breaking up large fat globules into smaller globules, thereby increasing the surface area that enzymes can use to digest the fat.

-bile breaks apart large fat globules.

**without bile, most of the fat taken into the body remains undigested.

simple sugar

-starch

-glucose is stored in the form of glycogen in liver cells.

process in which the liver converts stored glycogen back into glucose due to blood sugar level becomes dangerously low.

process in which the liver can convert proteins and fats into glucose, when the body needs sugar.

-the upper & middle section of the stomach.

**are a reservoir for ingested food and an area for action by acid and pepsin (gastric enzyme).

-the lower section of the stomach

**a muscular grinding chamber that breaks up food and feeds it gradually into the duodenum.

brings blood to the liver from the intestines.

**digested food pass into the portal vein directly after being absorbed into the capillaries of the small intestine, thus giving the liver the first chance to use the nutrients.

-is both an exocrine & endocrine organ.

• -As an exocrine gland, it produces enzymes:
• to digest starch, such as,
• amylase (amyl/o = starch; -ase = enzyme),
• to digest fat, such as
• lipase (lip/o = fat), and
• to digest proteins, such as
• protease (prote/o = protein).

-As an endocrine gland (secreting into the bloodstream), the pancreas secretes insulin.

**These pass into the duodenum through the pancreatic duct.

1. Obstruction and bacterial infection cause red, swollen, and inflamed appendix.

2. Pus and bacteria invade the wall of the appendix.

3. Pus perforates (ruptures through) the wall of the appendix into the abdomen, leading to peritonitis (inflammation of the peritoneum).

Ex. of enteroenterostomy (-stomy means two or more combining forms (enter/o & enter/o) indicates the surgical creation of a new opening between those parts of the body.

• 1) End to end
• 2) End to side
• 3) Side to side

* Hiatal hernia, occurs when the upper part of the stomach protrudes upward through the diaphragm. This condition lead to GERD.

• * Inguinal hernias
• --direct inguinal hernia, occurs through the abdominal wall in an area of muscular weakness.
• --indirect inguinal hernia, occurs through the inguinal canal (passageway in the lower abdomen), where the herniated tissue/bowel descends into the scrotal sac.

1) Stone in the gallbladder causing mild or no symptoms.

2) Stone obstructing the cystic duct, causing pain

3) Stone obstructing the common bile duct, causing pain and jaundice.

4) Stone at the lower end of the common bile duct and pancreatic duct, causing pain, jaundice, and pancreatitis.