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Medical sociology > Digestive system > Flashcards

Digestive system Flashcards

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USMLE® Step 1 flashcards Sociology 101 flashcards
1
Q

digestive system

A

includes organs that:

•ingest the food

•transport the ingested material

•digest the material into smaller usable components

•absorb the necessary digested nutrients into the bloodstream

•expel waste products from the body

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2
Q

digestive system

A

composed of:

1.Digestive organs

make up the gastrointestinal (GI) tract, also called the *DIGESTIVE TRACT or * the ALIMENTARY CANAL

2.Accessory digestive organs

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3
Q

General Structure
of the Digestive System

A

•The GI tract organs:

–oral cavity

–pharynx

–esophagus

–stomach

–small intestine

–large intestine

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4
Q

Accessory Organs of Digestive system

A

not part of the long GI tube,

often develop as outgrowths of that tube.

They are as follows:

  • teeth
  • tongue
  • •salivary glands
  • ** liver**
  • gall bladder

• pancreas

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5
Q

Digestive System Functions

A

•Ingestion

•Digestion

–mechanical digestion

–chemical digestion

•Propulsion

–peristalsis

–segmentation

  • Secretion
  • Absorption
  • Elimination of wastes (defecation)
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6
Q

Peristalsis and Segmentation

A

•Propulsion of food along the GI tube involves two types of movement:

–peristalsis

–segmentation

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7
Q

** Peristalsis**

A

the ripple-like wave of muscular contraction that forces material to move further along the GI tract

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8
Q

Segmentation

A

the churning and mixing of material helping to disperse the material and mix it and combine it with digestive organ secretions.

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9
Q

Oral Cavity (mouth)

A
  • Initial site of mechanical digestion (via mastication) and chemical digestion (via enzymes in saliva).
  • Bounded anteriorly by the teeth and lips

posteriorly by the oropharynx.

  • Vestibule is the space between the cheeks or lips and the gums.

•Oral cavity proper

•Lips (labia).

•Gingivae (gums)

•Labial frenulum

•Fauces

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10
Q

Palate

A

The palate forms the roof of the oral cavity

The anterior two-thirds of the palate is called the hard palate because it is comprised of bone.

•The posterior one-third of the palate is soft and muscular and is called the soft palate.

Extending from the soft palate posteriorly is the uvula, which elevates during swallowing and closes off the posterior entrance to the nasopharynx

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11
Q

Tongue

A
  • The tongue MANIPULATES and MIXES INGESTED materials during chewing and helps compress the partially digested materials into a bolus.
  • A bolus is a globular mass of ingested materials that can be more easily swallowed.
  • The inferior surface of the tongue attaches to the floor of the oral cavity by a thin, midline mucous membrane called the lingual frenulum.

•Performs important functions in swallowing.

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12
Q

Salivary Glands

A
  • Salivary glands produce and secrete saliva into the oral cavity **(1-1.5 Liters/day)
  • SALIVA FUNCTIONS:

–moistens ingested materials to become a slick bolus

–moistens, cleanses, and lubricates the structures of the oral cavity

–chemical digestion of ingested materials

–antibacterial action

–dissolves materials so that taste receptors on the tongue can be stimulated

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13
Q

Salivary Glands:

A

Three pairs of salivary glands

located external to the oral cavity:

• parotid glands

• submandibular glands

• sublingual glands

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14
Q

Parotid Salivary Glands

A
  • Largest of the three salivary glands
  • Located anterior and inferior to the ear
  • Secrete 25–30% of total saliva
  • Parotid duct runs parallel to the zygomatic arch and pierces the buccinator muscle just opposite the second upper molar
  • Also secrete amylase (carbohydrate breakdown)
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15
Q

Submandibular Salivary Glands

A
  • Reside inferior to the body of the mandible
  • Produce the majority of the saliva _ (60–70%)_
  • submandibular duct transports saliva from each gland through a papilla in the floor of the mouth on the lateral sides of the lingual frenulum
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16
Q

Sublingual Salivary Glands

A

•Inferior to the tongue

  • Each gland extends multiple tiny sublingual ducts that open onto the inferior surface of the oral cavity just posterior to the submandibular duct papilla
  • Contribute only 3–5% of total saliva
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17
Q

Teeth

A

•The teeth known as DENTITION.

•Dentin forms the primary mass of the tooth. It is harder than bone.

•Each root is covered with cementum.

The external surface of the dentin is covered with a layer of enamel that forms the crown of the tooth

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18
Q

Teeth

A
  • The center of the tooth is a pulp cavity that contains connective tissue called pulp.
  • A root canal opens into the connective tissue through an opening called the **apical foramen. **

Blood vessels and nerves pass through **apical foramen **and are housed in the pulp.

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19
Q

Teeth

A

Two sets of teeth develop and erupt in a normal lifetime:

•** deciduous teeth**

—erupt between 6–30

months, 20 in number, and are often

called milk teeth

• permanent teeth

—replace the deciduous

teeth and are 32 in number

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20
Q

Permanent Teeth

A

•Incisors

—most anteriorly placed, shaped like chisels, and have a single root

•Canines

—posterolateral to the incisors, pointed tips for puncturing and tearing

•Premolars

—posterolateral to canines, have flat crowns with prominent ridges called cusps for crushing and grinding

•Molars

—thickest and most posterior teeth, also adapted for crushing and grinding of ingested materials

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21
Q

Pharynx

A
  • Shared by the respiratory and digestive systems
  • Three skeletal muscle pairs of pharyngeal constrictors (superior, middle, and inferior) form the wall of the pharynx and participate in swallowing

•CN X innervates most pharyngeal muscles

•Branches of external carotid arteries supply the pharynx •INTERNAL JUGULAR veins drain the pharynx

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22
Q

Peritoneum

A

Abdominopelvic cavity is covered with moist serous membranes:

• parietal peritoneum

—lines the **inside **surface of the body wall

• visceral peritoneum

—covers the surface of INTERNAL ORGANS WITHIN the cavity

23
Q

Peritoneum

A

•Organs that are completely surrounded by visceral peritoneum are called intraperitoneal organs.

They include the stomach and most of the small intestines.

•Organs that lie in direct contact with the posterior abdominal and pelvic walls and are only covered on their anterolateral surfaces with visceral peritoneum are called retroperitoneal organs.

Examples are the

pancreas,

ascending and descending colon of the large intestines, the rectum.

24
Q

The Peritoneal Cavity and Peritoneum

A

•Mesenteries

– are double layered folds of peritoneum stabilize INTRAPERITONEAL GI TRACT ORGANS

–Holds organs in place

–Sites of fat storage

–Provides a route for circulatory vessels and nerves

  • blood vessels, lymphatic vessels, and nerves supply digestive organs
25
Q

The Wall of the Abdominal

GI Tract

A

The wall of the GI tract from the esophagus to the large intestine is composed of four concentric layers called tunics.

From deep (in contact with ingested materials)

to superficial (the external covering) they are:

  • mucosa(deep)
  • submucosa
  • muscularis
  • adventitia or serosa(supperficial)
26
Q

Mucosa

(tunic of the GI TRACT)

DEEPEST LAYER

A

There are three components to this deepest layer:

  • an inner superficial epithelium
  • an underlying areolar connective tissue
  • a thin layer of smooth muscle
27
Q

Submucosa

(tunic of the GI TRACT)

A

Components include:

– lymphatic ducts

– mucin-secreting glands

– blood vessels

– Nerves

28
Q

Muscularis

(tunic of the GI TRACT)

A

•Two layers of smooth muscle:

Inner circular layer

  • constricts the lumen and forms sphincters

outer longitudinal layer

  • shorten the tube

•Two exceptions:

–esophagus has a mix of both smooth and skeletal muscle –stomach contains three layers of smooth muscle

29
Q

Adventitia or Serosa

(tunic of the GI TRACT)

SUPERFICIAL LAYER

A
  • OUTERMOST LAYER(SUPERFICIAL)
  • Areolar connective tissue with collagen and elastic fibers
30
Q

Blood Supply

A

Three unpaired arteries supply the abdominal GI tract:

• celiac trunk

• superior mesenteric artery

• inferior mesenteric artery

31
Q

Lymphatic Vessels and Structures

A

**•LACTEALS **are present in villi of the small intestines.

•Lymph ducts transport lymph to the cisterna chyli, which drains into the thoracic duct.

Lymphatic structures called MALT (mucosa-associated lymphatic tissue) are found in the small intestine and appendix. These aggregate nodules are called Peyer patches

32
Q

Esophagus

A
  • A tubular passageway that conducts ingested materials from the pharynx to the stomach.
  • Passes through an opening in the diaphragm called the esophageal hiatus as it connects to the stomach.
  • Approximately 25 cm long coursing anterior to the vertebral bodies
  • About 1.5 cm is in abdomen prior to changing into the stomach
  • Lumen collapsed when empty
33
Q

Esophageal Sphincters

A

The esophagus has two sphincters:

•Superior esophageal sphincter

—at the junction of the pharynx and the esophagus; closes during inhalation preventing air from entering the GI tract

Inferior esophageal sphincter

—at the junction of the esophagus and the stomach; along with the esophageal opening of the diaphragm, prevents materials from regurgitating from the stomach into the esophagus

34
Q

Phases of Swallowing

A

There are three phases of swallowing:

•voluntary phase

•pharyngeal phase

•esophageal phase

35
Q

Stomach

A

•Upper left quadrant of abdomen •

It continues the mechanical and chemical digestion of the bolus

  • The bolus eventually is processed into a pastelike soup called chyme
  • Possesses three layers of muscle to aid in the mechanical processing of ingested materials
36
Q

Regions of the Stomach

A

•The stomach is composed of four regions:

–cardia

–fundus

–body

–Pyloris (•Pyloric sphincter )

  • The inferior border of the stomach is the greater curvature and the superior border is the inferior curvature(LESSER CURAVATURE).
  • The internal surface of the stomach is thrown into folds called gastric folds (rugae)
37
Q

The Stomach

A

Function:

  • Site where food is churned into chyme (paste) •Breakdown of food protein begins
  • Many secretions:

gastric juices and mucin**

•Some absorption occurs

– water, electrolytes, some drugs (aspirin, alcohol)

•Food remains in stomach for ~4-5 hours

38
Q

Small Intestine

A
  • Finishes the chemical digestion process and is responsible for absorbing most of the nutrients
  • Ingested materials spend at least 12 hours in the small intestine as chemical digestion and absorption are completed

About 6 meters (20 feet) long in an unembalmed cadaver but much shorter in a living individual due to muscle tone

  • Extends from the pylorus of the stomach to the cecum of the large intestine, and occupies a significant portion of the abdominal cavity
39
Q

Small Intestine

A

Consists of three specific segments (from proximal to distal from the stomach):

• duodenum—25 cm (10 inches) (proximal)

• jejunum—2.5 m (7.5 feet)

• ileum—3.6 m (10.8 feet) (distal)

40
Q

Duodenum

A

•C-shaped

•Upper right quadrant

•Receives digestive enzymes from the pancreas (main pancreatic duct) and bile from the liver and gallbladder (common bile duct)

41
Q

Jejunum

A

•Middle portion of the small intestine

**•PRIMARY REGION FOR CHEMICAL DIGESTION AND NUTRIENT ABSORPTION **

42
Q

Ileum

A

•Last segment of the small intestine

•Distal end terminates at the ileocecal valve,

** ileocecal valve, **a sphincter that controls the entry of materials into the large intestine

43
Q

Large Intestine

A
  • The large intestine forms a three-sided perimeter around the centrally located small intestine (5 ft)
  • Diameter is 6.5 cm (2.5 in) vs. 2.5 cm of the small intestine, thus the name large intestine

•Absorbs fluids and ions and compacts undigestible wastes and solidifies them into feces

•Stores the feces until defecation (expulsion of the feces)

44
Q

Large Intestine

A

The large intestine is comprised of the following structures:

• cecum

• ascending colon

• transverse colon

• descending colon

• sigmoid colon

**• rectum • **

anal canal

**appendix (lymphatic)

45
Q

Accessory Digestive Organs

A

Includes the following organs:

  • liver
  • gall bladder
  • pancreas
  • biliary apparatus
46
Q

Liver

A
  • Located in right quadrant of abdomen
  • Comprised of four incompletely separated lobes:

–right lobe

–left lobe

–caudate lobe

–quadrate lobe

47
Q

** Functions of The Liver**

A

Produce bile.

  • BILE; a greenish fluid that **breaks down fats into small droplets to assist in their chemical digestion **
  • Detoxify drugs, metabolites, and poisons.
  • Store excess nutrients and vitamins and release them when they are needed.
  • Synthesize blood plasma proteins such as albumins, globulins, and proteins required for blood clotting.
  • Phagocytize debris in the blood.
  • Help break down and recycle components of aged erythrocytes and damaged or worn-out formed elements.
48
Q

** Gall Bladder**

A
  • Embedded on the inferior surface of the liver
  • **Functions: collect and concentrate bile **
  • The cystic duct connects the gall bladder to the common bile duct
49
Q

Pancreas

A

Has both endocrine (Chapter 20) and exocrine functions

Exocrine functions: secreting digestive enzymes and bicarbonate, collectively called pancreatic juices, into the duodenum via the pancreatic duct into the duodenum

50
Q

Biliary Apparatus

A

Network of thin ducts that transport bile from liver and gall bladder to duodenum

Function of the gall bladder is storage (not production) of bile

51
Q

Biliary Apparatus

A

Left and right lobes of the liver drain bile into the left and right hepatic ducts.

Left and right hepatic ducts merge to form the common hepatic duct.

**The cystic duct and the common hepatic duct merge to form the common bile duct. **

The common hepatic duct and the main pancreatic duct enter the duodenum through the hepatopancreatic ampulla.

52
Q

Question

A

The three pairs of multicellular salivary glands that secrete into the oral cavity are the ____________ glands.

A. alpha, beta, and gamma

B. parotid, submandibular, and sublingual

C. palatine, lingual, and pharyngeal

D. serous, mucous, and mixed

53
Q

Intestinal Disorders

A
  • Celiac disease – autoimmune disorder of the small intestine (gluten sensitivity)
  • **Inflammatory bowel disease **
  • -Inflammation of intestinal wall
  • Crohn’s disease
  • – deep fissures/ulcers along entire intestine
  • Ulcerative colitis – shallow inflammation of large intestine, mainly in rectum
54
Q

The Digestive System in Later Life

A

Middle age – gallstones and ulcers

Old age – activity of digestive organs decline

Fewer digestive juices and enzymes produced

Absorption is less efficient

Dehydration of fecal mass leads to constipation

Diverticulosis and cancer of digestive organs

Medical sociology (8 decks)

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