Digestive System -- DEFINITIONS

chol/e

gall, bile

col/o

colon

cyst/o

bladder, sac

duoden/o

duodenum

emet/o

vomit

enter/o

intestine

esophag/o

esophagus

gastr/o

stomach

gingiv/o

gums

gloss/o

tongue

hepat/o

liver

peps/o

digestion

rect/o

rectum

sigmoid/o

sigmoid colon

Alimentary Canal

hollow tube structures of the digestive system

esophagus, stomach, small intestine, and large intestine

major organs and structures of the digestive system

liver, pancreas, gallbladder, cecum, teeth, and salivary glands

accessory structures of digestive system

ingestion, digestion, absorption, and defecation

functions of the digestive system

Teeth

accessory structure of the digestive system which is responsible for the mechanical digestion of food through chewing, increasing its surface area for easier enzymatic digestion

Tongue

accessory structure of the digestive system which is a muscular organ that manipulates food during chewing and helps form the bolus; it also contains taste buds and initiates swallowing

Salivary Glands

accessory structure of the digestive system which produces saliva that contains enzymes and mucus

Liver

accessory structure of the digestive system which produces bile for emulsifying fats for digestion, processing nutrients absorbed from the small intestine, and detoxifying harmful substances

Gallbladder

accessory structure of the digestive system which stores and concentrates bile and releases it into the duodenum when needed for fat digestion

Bile Ducts

accessory structure of the digestive system which is a series of channels that transport bile from the liver and gallbladder to the duodenum

Pancreas

accessory structure of the digestive system which secretes digestive enzymes into the small intestine to help break down fats, carbohydrates, and proteins

0.5 meters

how long is the digestive system from the tongue to the duodenum?

5.5 - 6.0 meters

how long is the small intestine?

1.5 meters

how long is the large intestine?

smaller molecules

Because the food we eat is too big to be directly passed into the blood, the goal of the digestive system is to:

1. Digest food into ______________________________.

2. Absorb smaller molecules into the _____________.

1 = ?

blood

Because the food we eat is too big to be directly passed into the blood, the goal of the digestive system is to:

1. Digest food into ______________________________.

2. Absorb smaller molecules into the _____________.

2 = ?

Mechanical Digestion

physical breakdown of food into smaller pieces which forms a greater surface area for contact with digestive enzymes

Chemical Digestion

splitting of complex, non-absorbable food molecules into small, absorbable nutrient molecules by hydrolysis; uses enzymes that speed up the reaction and enable digestion to occur

Oral Cavity

• located at the entrance of the digestive tract

• where mechanical (chewing) and chemical (saliva) digestion starts

• houses the teeth, tongue, and salivary gland openings

• includes the cheeks, tongue, floor, and palate

Hard Palate

• forms the anterior portion of the roof of the mouth

• made up of the maxilla and palatine bones

• separates the oral cavity from the nasal cavity

• provides a rigid surface against which the tongue pushes food during chewing

bony roof

the hard palate is known as the:

Soft Palate

• lies posterior to the hard palate

• made of muscle and connective tissues

• flexible and helps close off the nasopharynx during swallowing to prevent food from entering the nasal cavity

• plays a role in speech and swallowing

soft tissue roof

the soft palate is also known as:

uvula

• small, fleshy projection that hangs from the center of the soft palate

• aids in speech and helps prevent food from entering the nasal cavity during swallowing by properly closing the nasopharynx

• plays a role in the gag reflex

stratified squamous epithelial tissue

the tissue that lines the entire oral cavity for protection against mechanical stress, abrasion, and pathogens

Deciduous Teeth

• baby teeth

• 20 teeth

• appears at 6 months of age

• usually shed at around 6-12 y/o

Permanent Teeth

• 32 teeth

• teeth that are meant to last into adulthood

Alveolus

• socket in the jawbone of the maxilla where a tooth is anchored

• provides structural support and stability

Periodontal Ligaments

• found between the tooth root and walls of the alveolus

• network of fibrous connective tissue that anchors the tooth to the alveolar bone, absorbs shock during chewing, and provides sensory feedback, and tooth movement

Crown

• visible part of the tooth above the gumline

• covered in enamel

• involved in biting and chewing

Enamel

• outermost layer covering the crown

• hardest substance in the human body

• protects the tooth from mechanical forces, acid, and decay

• not regenerative

Dentin

• lies beneath the enamel and surrounds the pulp cavity

• yellowish, porous material that is softer than enamel but harder than bone

• hard tissue that provides structure and support to the enamel

• transmits sensations to the nerve in the pulp cavity

Root

• portion of the tooth below the gumline which is embedded in the alveolus

• anchors the tooth to the jawbone

• may have one or more

Pulp Cavity

• central space inside the tooth

• made of nerves, blood vessels, and connective tissue

• keeps the tooth alive and responsive to stimuli

Dental Caries

• tooth decay

• breakdown of teeth due to acids and plaque buildup

Tongue

its purpose is to manipulate what is ingested and to provide the sense of taste

saliva

The parotid glands, the submandibular glands, and the sublingual glands produce ____________

Amylase

enzyme that breakdown starch into sugars

Lingual Lipase

enzyme for the digestion of fats

Mucus

enzyme that lubricates food for easier chewing and swallowing; protects the mouth from excessive acids

Lysozymes

antibacterial enzyme that helps kill or inhibit bacteria in the mouth

Antibodies

immune protection against pathogens entering via the oral cavity

Mechanical and chemical

Physiology of Digestion in the Mouth

1. _____________________________ digestion takes place in the mouth.

2. The __________________________ muscles move the jaw for mastication.

3. Amylase in saliva partially digests ____________________.

4. Mucus mixes with the food to make it easier to _________.

5. The bite of food is called a _____________ before it is swallowed.

1 = ?

masseter and temporalis

Physiology of Digestion in the Mouth

1. _____________________________ digestion takes place in the mouth.

2. The __________________________ muscles move the jaw for mastication.

3. Amylase in saliva partially digests ____________________.

4. Mucus mixes with the food to make it easier to _________.

5. The bite of food is called a _____________ before it is swallowed.

2 = ?

carbohydrates

Physiology of Digestion in the Mouth

1. _____________________________ digestion takes place in the mouth.

2. The __________________________ muscles move the jaw for mastication.

3. Amylase in saliva partially digests ____________________.

4. Mucus mixes with the food to make it easier to _________.

5. The bite of food is called a _____________ before it is swallowed.

3 = ?

swallow

Physiology of Digestion in the Mouth

1. _____________________________ digestion takes place in the mouth.

2. The __________________________ muscles move the jaw for mastication.

3. Amylase in saliva partially digests ____________________.

4. Mucus mixes with the food to make it easier to _________.

5. The bite of food is called a _____________ before it is swallowed.

4 = ?

bolus

Physiology of Digestion in the Mouth

1. _____________________________ digestion takes place in the mouth.

2. The __________________________ muscles move the jaw for mastication.

3. Amylase in saliva partially digests ____________________.

4. Mucus mixes with the food to make it easier to _________.

5. The bite of food is called a _____________ before it is swallowed.

5 = ?

Pharynx

• composed of nasopharynx, oropharynx, and laryngopharnyx

• located at the back of the mouth and nasal cavities

• connects the oral and nasal cavities to the esophagus and larynx

Nasopharynx

• located behind the nasal cavity

• for respiration

Oropharynx

• located behind the oral cavity

• shared passageway for air and food

laryngopharnyx

• located behind the larynx

• directs food to esophagus and air to larynx

Epiglottis

• flap of elastic cartilage that guards the opening of the larynx during swallowing

• folds down to cover the glottis to prevent food or liquid from entering the trachea

esophagus

• muscular tube that goes through the diaphragm to connect with the stomach

• moves food to the stomach via peristalsis

• lined with stratified squamous epithelium

Trigeminal, Facial, Glossopharyngeal, and Vagus

Physiology of Digestion from the Mouth to the Stomach:

1. Deglutition (swallowing) involves four cranial nerves (______________________).

2. The ____________ closes off the glottis so that the bolus moves to the esophagus.

3. Peristalsis moves the bolus through the esophagus.

1 = ?

epiglottis

Physiology of Digestion from the Mouth to the Stomach:

1. Deglutition (swallowing) involves four cranial nerves (______________________).

2. The ____________ closes off the glottis so that the bolus moves to the esophagus.

3. Peristalsis moves the bolus through the esophagus.

2 = ?

Peristalsis

Physiology of Digestion from the Mouth to the Stomach:

1. Deglutition (swallowing) involves four cranial nerves (______________________).

2. The ____________ closes off the glottis so that the bolus moves to the esophagus.

3. _________________ moves the bolus through the esophagus.

3 = ?

Tongue

STEPS IN SWALLOWING:

1. ____________ pushes the bolus to the back of the pharynx.

2. _____________ pushes up and the epiglottis closes over the glottis.

3. The bolus moves to the ___.

4. Esophageal muscles move the bolus toward the stomach through _________________.

1 = ?

Larynx

STEPS IN SWALLOWING:

1. ____________ pushes the bolus to the back of the pharynx.

2. _____________ pushes up and the epiglottis closes over the glottis.

3. The bolus moves to the ___.

4. Esophageal muscles move the bolus toward the stomach through _________________.

2 = ?

esophagus

STEPS IN SWALLOWING:

1. ____________ pushes the bolus to the back of the pharynx.

2. _____________ pushes up and the epiglottis closes over the glottis.

3. The bolus moves to the ___.

4. Esophageal muscles move the bolus toward the stomach through _________________.

3 = ?

peristaltic contractions

STEPS IN SWALLOWING:

1. ____________ pushes the bolus to the back of the pharynx.

2. _____________ pushes up and the epiglottis closes over the glottis.

3. The bolus moves to the ___.

4. Esophageal muscles move the bolus toward the stomach through _________________.

4 = ?

Stomach

• has three layers of smooth muscle

• its lining has rugae for gastric pits which leads to gastric glands

• grinding and mixing food with gastric juices

Longitudinal Layer

LAYERS OF THE STOMACH:

• outer layer

• shorten the stomach during contractions

Circular Layer

LAYERS OF THE STOMACH:

• middle layer

• responsible for mixing and churning food

Oblique Layer

LAYERS OF THE STOMACH:

• innermost

• enhances the grinding motion of the stomach

Rugae

• inner lining of the stomach (mucosa)

• folds in the stomach lining that allows it to expand when food enters

• increase surface area and help accommodate gastric pits and glands

Gastric Pits

small depressions in the rugae that leads down into the glands

Gastric Glands

located deeper in the mucosa which secretes gastric juice

Mucous Cells

CELLS OF THE GASTRIC GLANDS AND PITS:

• found in the neck

• produce alkaline mucus that coats and protects the stomach lining from HCl

Endocrine Cells

CELLS OF THE GASTRIC GLANDS AND PITS:

• located in the pyloric region

• produce gastrin which stimulates parietal cells to produce more acid and increase gastric motility

Parietal Cells

CELLS OF THE GASTRIC GLANDS AND PITS:

• found in the middle of the gland

• produce hydrochloric acid which kills microbes and activates pepsinogen into pepsin

• secretes intrinsic factor needed for vitamin B12 absorption in the small intestine

Chief Cell

CELLS OF THE GASTRIC GLANDS AND PITS:

• located at the base of the gland

• secrete pepsinogen, an inactivate enzyme that is converted to pepsin for protein digestion

• secrete gastric lipase for digestion of fats

Regenerative Cells

CELLS OF THE GASTRIC GLANDS AND PITS:

• found throughout the gland, especially near the base of the pits

• stem cells that rapidly divide and replace other types of gastric cells when damaged

medulla oblongata

Physiology of Digestion in the Stomach:

1. During swallowing, the _______________ sends signals to the stomach, telling it to relax.

2. The ________________________ opens to allow the bolus to enter.

3. __________ of the stomach walls starts peristaltic contractions.

4. The pyloric sphincter remains closed until the pH of the stomach contents reaches ___________.

5. Hydrochloric acid changes pepsinogen to pepsin so that ________ are partially digested.

6. Hydrochloric acid activates lingual lipase, which partially digests ______ along with gastric lipase.

7. Intrinsic factor binds to ____________ so that it can be absorbed later.

8. Once gastric secretions are mixed with the bolus, it is called __________.

1 = ?

cardiac sphincter

Physiology of Digestion in the Stomach:

1. During swallowing, the _______________ sends signals to the stomach, telling it to relax.

2. The ________________________ opens to allow the bolus to enter.

3. __________ of the stomach walls starts peristaltic contractions.

4. The pyloric sphincter remains closed until the pH of the stomach contents reaches ___________.

5. Hydrochloric acid changes pepsinogen to pepsin so that ________ are partially digested.

6. Hydrochloric acid activates lingual lipase, which partially digests ______ along with gastric lipase.

7. Intrinsic factor binds to ____________ so that it can be absorbed later.

8. Once gastric secretions are mixed with the bolus, it is called __________.

2 = ?

Stretching

Physiology of Digestion in the Stomach:

1. During swallowing, the _______________ sends signals to the stomach, telling it to relax.

2. The ________________________ opens to allow the bolus to enter.

3. __________ of the stomach walls starts peristaltic contractions.

4. The pyloric sphincter remains closed until the pH of the stomach contents reaches ___________.

5. Hydrochloric acid changes pepsinogen to pepsin so that ________ are partially digested.

6. Hydrochloric acid activates lingual lipase, which partially digests ______ along with gastric lipase.

7. Intrinsic factor binds to ____________ so that it can be absorbed later.

8. Once gastric secretions are mixed with the bolus, it is called __________.

3 = ?

two

Physiology of Digestion in the Stomach:

1. During swallowing, the _______________ sends signals to the stomach, telling it to relax.

2. The ________________________ opens to allow the bolus to enter.

3. __________ of the stomach walls starts peristaltic contractions.

4. The pyloric sphincter remains closed until the pH of the stomach contents reaches ___________.

5. Hydrochloric acid changes pepsinogen to pepsin so that ________ are partially digested.

6. Hydrochloric acid activates lingual lipase, which partially digests ______ along with gastric lipase.

7. Intrinsic factor binds to ____________ so that it can be absorbed later.

8. Once gastric secretions are mixed with the bolus, it is called __________.

4 = ?

proteins

Physiology of Digestion in the Stomach:

1. During swallowing, the _______________ sends signals to the stomach, telling it to relax.

2. The ________________________ opens to allow the bolus to enter.

3. __________ of the stomach walls starts peristaltic contractions.

4. The pyloric sphincter remains closed until the pH of the stomach contents reaches ___________.

5. Hydrochloric acid changes pepsinogen to pepsin so that ________ are partially digested.

6. Hydrochloric acid activates lingual lipase, which partially digests ______ along with gastric lipase.

7. Intrinsic factor binds to ____________ so that it can be absorbed later.

8. Once gastric secretions are mixed with the bolus, it is called __________.

5 = ?

lipids

Physiology of Digestion in the Stomach:

1. During swallowing, the _______________ sends signals to the stomach, telling it to relax.

2. The ________________________ opens to allow the bolus to enter.

3. __________ of the stomach walls starts peristaltic contractions.

4. The pyloric sphincter remains closed until the pH of the stomach contents reaches ___________.

5. Hydrochloric acid changes pepsinogen to pepsin so that ________ are partially digested.

6. Hydrochloric acid activates lingual lipase, which partially digests ______ along with gastric lipase.

7. Intrinsic factor binds to ____________ so that it can be absorbed later.

8. Once gastric secretions are mixed with the bolus, it is called __________.

6 = ?

vitamin B12

Physiology of Digestion in the Stomach:

1. During swallowing, the _______________ sends signals to the stomach, telling it to relax.

2. The ________________________ opens to allow the bolus to enter.

3. __________ of the stomach walls starts peristaltic contractions.

4. The pyloric sphincter remains closed until the pH of the stomach contents reaches ___________.

5. Hydrochloric acid changes pepsinogen to pepsin so that ________ are partially digested.

6. Hydrochloric acid activates lingual lipase, which partially digests ______ along with gastric lipase.

7. Intrinsic factor binds to ____________ so that it can be absorbed later.

8. Once gastric secretions are mixed with the bolus, it is called __________.

7 = ?

chyme

Physiology of Digestion in the Stomach:

1. During swallowing, the _______________ sends signals to the stomach, telling it to relax.

2. The ________________________ opens to allow the bolus to enter.

3. __________ of the stomach walls starts peristaltic contractions.

4. The pyloric sphincter remains closed until the pH of the stomach contents reaches ___________.

5. Hydrochloric acid changes pepsinogen to pepsin so that ________ are partially digested.

6. Hydrochloric acid activates lingual lipase, which partially digests ______ along with gastric lipase.

7. Intrinsic factor binds to ____________ so that it can be absorbed later.

8. Once gastric secretions are mixed with the bolus, it is called __________.

8 = ?

Negative Feedback

The moving of food to the small intestine is an example of ___________________ because when the pH of the chyme falls to two, the endocrine cells stop producing acids which causes the pyloric sphincter to open and chyme to leave the stomach into the duodenum.

Peptic Ulcers

erosions of the lining of the digestive tract

Esophageal ulcers

may happen in the lower esophagus if there is reflux of gastric juices through the cardiac sphincter

Gastric ulcers

in the stomach, usually from bacteria

Duodenal ulcers

the most common; caused when the chyme entering the duodenum is not sufficiently neutralized

Hepatic Lobules

• how the 4 lobes of the liver is arranged

• microscopic units that are shaped like hexagons

• contain hepatocytes