Physiology Of Digestion And Defecation

Question 1

The digestive tract/GI tract

Answer 1

1. Mouth
2. Esophagus
3. Stomach
4. Small intestine
5. Large intestine/colon

Question 2

Where does digestion begin and end

Answer 2

Mouth —> small intestine

Question 3

What is digestion controlled by?

Answer 3

Hormone and nerve regulation

Question 4

Mouth

Answer 4

• breaks down food into pieces for easy digestion - need to take 30 chews for proper digestion
• enzyme -containing saliva mixes with food pieces to begin breakdown for absorption and use
• food pieces travel to the throat (pharnyx) and then the esophagus

Question 5

Esophagus

Answer 5

• muscular tube extending from the pharynx to the stomach
• delivers food to the stomach by a series of rhythmic, smooth mm contractions called Perisalsis
• lower esophageal sphincter at the junction of the stomach called the zone of high pressure keeps food from passing backwards into the esophagus

Question 6

What is peristalsis

Answer 6

Series of rhythmic, smooth muscle contractions which delivers food from esophagus to stomach

Question 7

Stomach

Answer 7

• secretes acid and enzymes to continue food breakdown
• acts as a mixer and grinder
• food travels from the stomach to the small intestines as a liquid or paste called chyme

Question 8

Small intestine

Answer 8

• Peristalsis moves chyme through the small intestines and mixes it with digestive secretions
• the duodenum: widest and shortest part of the SI; C-shaped or horseshoe-shaped structure that lies in the upper abdomen near the midline
• duodenum begins the process of absorption of nutrients but also continues the process of breakdown using enzymes released from the pancreas and bile from the liver

Question 9

Parts of the small intestine:

Answer 9

• duodenum
• jejunum
• ileum

Question 10

Where is bile made and stored?

Answer 10

Made in liver —> stored in gallbladder

Question 11

How does bile enter the SI?

Answer 11

During a meal, the gallbladder contracts and sends bile into SI

Question 12

What is the function of bile?

Answer 12

Aids in digestion of fats and elimination of waste products from the blood

Question 13

What are the primary responsibilities of the Jejunum and ileum?

Answer 13

for absorption of nutrients into the bloodstream that are used for energy, growth, and cell repair

Question 14

Which part of the SI is more vascularized?

Answer 14

The jejunum - the presence of the villi increase the surface area allowing the greatest absorption here

Question 15

Where does the greatest amount of absorption happen?

Answer 15

Jejunum

Question 16

How long does it take chyme to travel through the small intestine?

Answer 16

24 hours

Question 17

What is left after absorption in small intestine?

Answer 17

Waste is left and passed dot the large intestine through the ileocecal valve and cecum on the right side of the trunk

Question 18

Large intestine/colon details:

Answer 18

• waste is passed through the cecum, ascending colon, transverse colon, and descending colon by peristalsis
• liquid is absorbed from the waste: solid waste (stool) is made up of food debris and good bacteria (also called gut flora or microbiome)— the good bacteria synthesize various vitamins and protects against harmful bacteria — continues the breakdown of sugars and fiber creating gas
• antibodies are produced that boosts the immune system
• takes about 36 hours for stool to get through the colon
• when the descending colon and sigmoid colon become full,a mass movement empties the stool into the rectum signaling a “call to stool” — usually associated with a meal — most active with the morning meal/breakfast

Question 19

What is the human microbiome?

Answer 19

The total DNA content of microbes inhabiting our bodies.
Composed of:
- bacteria
- archaea
- fungi
- viruses
- Protozoa
- Eukaryotic microbes

Question 20

Gut microbiome function

Answer 20

• affect our physiology, in health and in disease
• contribute to metabolic functions, protect against pathogens, instruct the immune system, and directly or indirectly affect most of our physiologic functions

Question 21

Healthy adult humans typically harbor ________ species of bacteria

Answer 21

More than 1000