Medical assisting Administrative and clinical procedures (5e) Chapter 33 The digestive system

After completing chapter 33, you will be able to: Describe the organs of the alimentary canal and their functions; explain the functions of the digestive system’s accessory organs; identify the nutrients absorbed by the digestive system and where they are absorbed; describe the causes, signs and symptoms, and treatments of various common diseases and disorders of the digestive system.

The Digestive

System

Learning Outcomes (cont.)

33.1 Describe the organs of the alimentary

canal and their functions

33.2 Explain the functions of the digestive

system’s accessory organs.

Learning Outcomes (cont.)

33.3 Identify the nutrients absorbed by the

digestive system and where they are absorbed.

33.4 Describe the causes, signs and

symptoms, and treatments of various

common diseases and disorders of the

digestive system.

– Alimentary canal organs form a

pathway extending from the mouth

to the anus – Accessory organs

Characteristics of the Alimentary Canal

• Mucosa

– Epithelial tissue

– Secretes enzymes and mucus

– Absorbs nutrients

• Submucosa – loose connective tissue,

blood vessels, glands, and nerves

Characteristics of the Alimentary Canal

Characteristics of the Alimentary Canal

(cont.)

• Movements

– Churning ~ mixes substances

– Peristalsis ~ moves substances

The Mouth

• Buccal cavity

• Mechanical digestion

• Starts chemical digestion

• Cheeks – hold food in mouth

• Lips – judge temperature of food

The Mouth

The Mouth (cont.)

• Tongue

– Mixes and holds food

between teeth – Contains taste buds

– Lingual frenulum

– Lingual tonsils

• Palate

– Hard palate – Soft palate – Uvula

• Lymphatic tissue

– Palatine tonsils – Pharyngeal tonsils or adenoids

The Mouth

The Mouth (cont.)

– Submandibular gland

– Sublingual gland

The Mouth (cont.)

• Teeth – decrease size

Pharynx

Pharynx (cont.)

Swallowing

nasal and oral cavity

into oropharynx

Pharynx

The Esophagus

• Connects pharynx to stomach

• Esophageal hiatus

• Cardiac sphincter

– Circular band of muscle

– Controls movement of food into stomach

Lower Esophagus Upper

Esophagus

The Stomach

• Absorbs

– Alcohol – Water – Some fat-soluble drugs

– Starts protein digestion

– Moves food into small intestine

The Stomach

• Sections

– Cardiac region

– Fundus

• Pyloric sphincter – controls movement

into the small intestine

Stomach

– Body – Pylorus

The Stomach

• Lining – gastric glands

– Cells ~ mucous, chief, and parietal

– Stimulated by

• Parasympathetic nervous system

• Gastrin – made by the stomach

– Inhibited by cholecystokinin (CCK) made by the small

intestine

Stomach

The Small Intestine

• Mesentery

Small Intestine

The Small Intestine (cont.)

• Intestinal lipase

– Stimulated by

• Parasympathetic nervous system

• Stretching of the intestinal wall

The Small Intestine (cont.)

• Absorbs most nutrients

• Wall contracts to mix and propel chyme

• Ileocecal sphincter – controls movement

of chyme into cecum of the large intestine

The Large Intestine

The Rectum and Anal Canal

• Defecation reflex

– Stimulated by mass movements

– Relaxation of anal sphincters

Rectum &

Anal Canal

Apply Your Knowledge

1 Matching:

_ Water, enzymes, and mucus E Bicuspids

_ Mass of food mixed with saliva and mucus F Pharyngeal

Apply Your Knowledge

2 What are the functions of the stomach?

ANSWER: The stomach’s functions are to receive

the bolus of food, mix it with gastric juice, start

protein digestion, and move food into the small

intestine It also absorbs alcohol, water, and some

drugs.

Apply Your Knowledge

3 Matching:

_ Vermiform appendix A Feces

_ Crosses the abdomen B Ascending colon

_ Up right side of abdomen C Anal canal

_ S-shaped tube D Defecation reflex

_ Down left side of abdomen E Sigmoid

_ Leftover chyme F Transverse colon

_ Last section of rectum G Cecum

_ Allows anal sphincters to relax H Descending colon

Characteristics of the Digestive Accessory Organs

• The Liver

– Hepatic lobules

• Smaller divisions of lobes

• Macrophages

– Hepatic portal vein

– Part of liver’s function

~ store vitamins and iron

To Liver

The Liver (cont.)

• Hepatic duct

– Bile from liver

– Merges with cystic duct and forms common bile duct

• Common bile duct ~ delivers bile to

duodenum

To Liver

The Gallbladder

• Only function is to store bile

– Cholecystokinin stimulates gallbladder to

release bile

– Bile salts

• Break up large fat globules

• Increase absorption of fatty acids, cholesterol, and fat-soluble vitamins

To Gallbladder

• Releases bicarbonate ions into duodenum

• Stimulated to release enzymes by

– Parasympathetic nervous system

– Secretin and cholecystokinin

Apply Your Knowledge

1 What is the route of bile through the liver and

gallbladder?

ANSWER: Bile is made in the hepatocytes and leaves the liver through the hepatic duct The hepatic duct merges with the

cystic duct from the gallbladder to form the common bile

duct, which delivers bile to the duodenum.

Apply Your Knowledge

2 What are the pancreatic enzymes and what do

they do?

ANSWER: They are:

Pancreatic amylase – digests carbohydrates

Pancreatic lipase – digests lipids

Nucleases – digest nucleic acids

Trypsin, chymotrypsin, and carboxypeptidase – digest proteins

Good Job!

The Absorption of Nutrients

• Nutrients – necessary food substances

The Absorption of Nutrients (cont.)

• Carbohydrates

– Starches ~ polysaccharides

– Simple sugars

• Monosaccharides and disaccharides

– Cellulose – provides fiber or bulk

The Absorption of Nutrients (cont.)

The Absorption of Nutrients (cont.)

• Vitamins

– Fat-soluble

– Water-soluble

• Minerals

– Found in bones and teeth

– Used to make enzymes, cell membranes, and

proteins

• Protein

– Requirements vary – Used for growth and tissue repair

Apply Your Knowledge

True or False:

_ Carbohydrates are starches, simple sugars, and cellulose.

_ Excess glucose is stored in the gallbladder as glycogen.

_ Triglycerides are the least abundant lipids

_ Linoleic acid is an essential fatty acid.

_ A, D, E and K are water-soluble vitamins.

_ Minerals are used by cells to make enzymes.

fat-soluble

Aging and the Digestive System

• Dietary changes due to

– Isolation– Depression

Common Diseases and Disorders

Disease/Disorder Description

Appendicitis Inflammation of the appendix;

can be life-threatening if not treated promptly

Cirrhosis Chronic liver disease; normal

tissue is replaced with nonfunctional scar tissueCholelithiasis (gall

stones) Hard deposits of cholesterol or bilirubin in the gall bladder

Common Diseases and Disorders

Disease/Disorder Description

intestine; can be acute or chronic

Colorectal cancer Arises from lining of rectum or

colon; curable if treated earlyConstipation Difficult defecation

Crohn’s disease Inflammatory bowel disease;

typically effects small intestine

Common Diseases and Disorders (cont.)

Disease/Disorder Description

usually self-limitingDiverticulitis Inflammation of diverticula

Diverticulosis – diverticula with

no inflammation

lining; “upset stomach”

Common Diseases and Disorders (cont.)

Disease/Disorder Description

disease (GERD); stomach acids push into esophagusHemorrhoids Varicose veins of rectum or anusHepatitis Inflammation of the liver; various

typesHiatal hernia Portion of stomach protrudes

into the chest through an opening in the diaphragm

Common Diseases and Disorders (cont.)

Disease/Disorder Description

Inguinal hernia Portion of large intestine

protrudes in the inguinal canal (where thigh and trunk meet) or,

in males, into the scrotum

Oral cancer Usually involves the lips or

tongue but can occur anywhere

in the mouth; tends to spread rapidly

Common Diseases and Disorders (cont.)

Disease/Disorder Description

Pancreatic cancer Fourth leading cause of cancer

deaths in the U.S

Stomach cancer Commonly in cardiac portion of

the stomach; occurs more frequently in Japan, Chili, and Iceland

Stomach ulcers Breakdown in lining of the

stomach

Apply Your Knowledge

Matching:

_ Inflammation of the large intestine A Heartburn

_ Inflammatory bowel disease B Hemorrhoids

_ Watery and frequent feces C Constipation

_ Difficult defecation D Crohn’s disease

_ Inflammation of the stomach lining E Colitis

_ Inflammation of pouches in the intestinal wall F Diarrhea

In Summary

33.1 The pathway of food through the

alimentary canal starts with the mouth and continues through the pharynx,

esophagus, stomach, small intestine,

large intestine, and anal canal

In Summary (cont.)

33.2 The accessory organs to the digestive

system include the liver, gallbladder, and pancreas

33.3 Nutrients absorbed by the body include

carbohydrates, proteins, lipids, vitamins, minerals, and water Most of the

absorption takes place in the small

intestine

In Summary (cont.)

33.4 There are many common diseases and

disorders of the digestive system with varied signs, symptoms, and

treatments

Take all that is given whether wealth, love

or language; nothing comes by mistake and with good digestion all

can be turned to

health

~ George Herbert

End of Chapter 33