Gastrointestinal System

Alimentary canal

GI tract

* Mouth
* Pharynx
* Esophagus
* Stomach
* Intestines
* Rectum
* Anus

What does the GI tract consist of?

Accessory GI organs

What type of organs are the liver, gall-bladder, biliary duct system and pancreas?

Digestion and elimination (through feces)

What are the two main functions of the GI system?

Buccal cavity or oral cavity

What are the other names for mouth?

Palate

The roof of the mouth

* Ducts connect the mouth with 3 majors pairs of **salivary glands →** secrete **saliva** to moisten food and convert starch into maltose

What is the mechanism of the mechanical breakdown of food?

* Parotid (at the side of face, in front of and below the external ear)
* Submandibular (beneath the lower jaw)
* Sublingual (beneath the tongue)

Where are the three pairs of salivary glands located?

Pharynx

Throat (extend from the base of the skull to the esophagus)

Aid swallowing by grasping food and propelling it toward the esophagus

What is the role of the pharynx?

Esophagus

A hollow, muscular tube that extends from the pharynx through the mediastinum to the stomach

Esophageal sphincter

* A sphincter at the upper border of the esophagus
* Relax for food to enter the esophagus

Peristalsis

* The rhythmic contraction and relaxation of smooth muscle
* Propel liquids and solids through the esophagus into the stomach

Stomach

A pouchlike structure in the **upper left part** of the abdominal cavity, just below the diaphragm

* Open the stomach when the food enter
* Prevent stomach content from reflux

What are the roles of **the cardiac sphincter?**

The greater curvature

The lateral surface of the stomach

The lesser curvature

The medial surface of the stomach

The cardia

A storage space of the stomach which **lies near the junction of the stomach and esophagus**

The fundus

A storage space of the stomach which **is the enlarged portion above and to the left of the esophageal opening into the stomach**

The body

A storage space of the stomach which is **the middle portion of the stomach**

The pylorus

A storage space of the stomach which is **the lower portion, lying near the junction of the stomach and the duodenum**

Chyme

A semifluid substance that the stomach breaks down into

* Duodenum (the most superior division, most active in digestion)
* Jejunum (the middle portion)
* Ileum (the most inferior portion)

What are the three major divisions of the **small intestine?**

Ileocecal valve

The valve between the ileum of the small intestine and the 1st segment of the large intestine

Absorb food molecules through its wall into the circulatory system

What is the role of the **small intestine?**

Absorb water, secrete mucus, eliminate digestive wastes

What is the role of the **large intestine?**

* Cecum
* Ascending colon
* Transverse colon
* Decesding colon
* Sigmoid colon
* Rectum

What are the 6 segments of the **large intestine?**

* Mucosa (tunica mucosa)
* Submucosa (tunica submucosa)
* Tunica muscularis

What are the three layers of the wall of the GI tract?

Epithelial and surface cells and loose connective tissue

What does **the mucosa** consist of?

* Loose connective tissue
* Blood and lymphatic vessels

What does **the submucosa** consist of?

* Skeletal muscle
* Longitudinal and circular smooth muscle fibers

What does the **tunica muscularis** consist of?

Visceral peritoneum

The membrane that cover the surface of most organs in the abdomen, including the abdomen

Tunica adventitia

What is the visceral peritoneum called when it’s in the **esophagus and rectum?**

Tunica serosa

What is the visceral peritoneum called when it’s in elsewhere in the GI tract?

Parietal peritoneum

A membrane that lines the inside of your abdomen and pelvis

Hepatopancreatic ampulla

(Ampulla of Vater)

A duct that delivers bile and pancreatic juice from the liver to the pancreas unite at a flasklike junction

Hepatopancreatic sphincer

(Oddi’s sphincter)

A muscular valve that controls the entry of bile and pancreatic juice

Lobule

The liver’s functional unit that consist of hepatic cells that encircle a central vein and radiate outward

Hepatocytes

Hepatic cells

Sinusoids

The liver’s capillary system

Kupffer’s cells

The cells that **line the sinusoid**, help **remove the bacteria and toxin**s that have entered the blood through the intestinal capillaries

Common hepatic duct

A tube that carries bile from the liver

Cystic duct

A duct from the gallbladder

Common bile duct

What does **the cystic duct** and **the common hepatic duct** join and form?

* Water, cholesterol, bile salts, electrolytes, phospholipids

What are the components of bile?

* Break down fat
* Neutralize gastric secretion in chyme

What are the roles of bile?

Assist with excretion of **conjugated bilirubin**

How does bile prevent jaundice?

Gallbladder

A pear-shaped organ that’s under the liver and join the larger organ by the **cystic duct**

Store and concentrate bile produced by the liver

What is the role of the gallbladder?

Cholecystokinin

What hormone stimulate the contraction of the gallbladder, which leads to the relaxation of the hepatopancreatic ampulla and the release of bile into the common bile duct for delivery to the duodenum?

* Neck: extending to **the curve of the duodenum**
* Tail: lying against **the spleen**

Where does the neck and the tail of the pancreas lie?

Endocrine cells

Pancreatic cells that secrete hormones into the blood

Exocrine cells

Pancreatic cells that secrete enzymes through ducts to the digestive system

Islets of Langerhans

Microscopic structure that is found in the pancreas’s endocrine

Secrete **glucagon →** stimulate **glycongenolysis** in the liver

What is the role of the **alpha cells** in the Islets of Langerhans?

Secrete **insulin →** promote carbohydrate metabolism

What is the role of the **beta cells** in the Islets of Langerhans?

Aaron’s sign

A pain in the chest or abdominal area that’s elicited by applying gentle but steadily increasing pressure over McBurney’s point below the right anterior superioir spine of the ilium, on a line between that spine and the umbilicus

Appendicitis

What does the positive Aaron’s sign indicate?

Abdominal distention

Increased abdominal girth resulted from increased intra-abdominal pressure forcing the abdominal wall outward

Anorexia

Loss of appetite

Ascites

Abnormal accumulation of serous fluid in the peritoneal cavity

Ballottement

A method that includes lightly tapping and bouncing fingertips against the abdominal wall, elicits abdominal muscle resistance or guarding

Absent bowel sounds

When no bowel sounds are heard

Borborygmi

A familiar **growling stomach** of a hungry patient

Hyperactive bowel sounds

Rapid, high-pitched, loud gurgling bowel sounds

Hypoactive bowel sounds

Bowel sounds that occur at a rate no greater than one per min

Cachexia

A profound state of overall ill health and malnutrition characterized by weakness and emaciation

Colic

Acute abdominal pain

Constipation

Hard and dry stool

Cullen’s sign

* Irregular, bluish hemorrhagic patches on the skin around the umbilicus and sometimes around abdominal scars
* Indicate massive hemorrhage

Diarrhea

* Rapid movement of fecal material
* Watery stool

Dyspepsia

Gastric discomfort (fullness, heartburn, bloating, nausea) that occurs after eating

Dysphagia

Difficult or painful swallowing

Emesis

An expulsion of the stomach contents by vomiting

Fecal impaction

Accumulation of hardened feces in the rectum or sigmoid colon that cannot be evacuated

Fecal incontinence

Inability to prevent the discharge of feces

Flatulence

A sensation of gaseous abdominal fullness

Grey Turner’s sign

* A bruiselike discoloration of the skin of the flanks
* Appears 6-24h after the onset of retroperitoneal hemorrahge in acute pancreatitis

Guarding

Moving away of flinching when a tender area of the abdomen is touched

Heartburn (Pyrosis)

A burning sensation in the esophagus or below the sternum in the region of the heart

Hematemesis

Vomiting blood

Hematochezia

Fresh, bright red blood passed from the rectum

Hemoperitoneum

Leakage of blood into the peritoneal cavity

Hepatomegaly

Enlarged liver

Hypogastrium

The lowest, middle abdominal region

Ileus

Mechanical intestinal obstruction

Jaundice

Yellow appearance of the skin, mucous membrane and sclerae of the eyes, resulting from elevated serum bilirubin levels

Meconium

The substance that fills the entire intestine before birth

Melena

Black, tarry stool (sign of GI tract bleeding)

Murphy’s sign

* Pain on the deep inspiration that occurs when an inflamed gallbladder is palpated by pressing the fingers under the rib cage
* Hepatitis can produce a positive sign

Nausea

An unpleasant feeling that typically precedes vomiting

Occult blood

An amount of blood so mall that it can only be seen or detected by chemical test or microscopic examination

Odynophagia

Painful swallowing

Pica

The craving and ingestion of normally inedible substances such as charcoal, plaster, clay, wool, etc

Polyphagia

Consuming abnormally large amounts of food

Polydipsia

Chronic, excessive thirst

Blumberg’s sign (rebound tenderness)

A pain that occurs when a hand pressing on the abdomen is suddenly released

Rectal tenesmus

* A spasmodic contraction of the anal sphincter with a persistent urge to defecate and involuntary, ineffective straining
* Occur in IBS

Regurgitation

Backflowing or return of food and fluids into the mouth without nausea or belching

Rigidity

A stiff abdominal wall