Physiology Of Digestion And Defecation Flashcards
The digestive tract/GI tract
- Mouth
- Esophagus
- Stomach
- Small intestine
- Large intestine/colon
Where does digestion begin and end
Mouth —> small intestine
What is digestion controlled by?
Hormone and nerve regulation
Mouth
- 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
Esophagus
- 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
What is peristalsis
Series of rhythmic, smooth muscle contractions which delivers food from esophagus to stomach
Stomach
- 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
Small intestine
- 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
Parts of the small intestine:
- duodenum
- jejunum
- ileum
Where is bile made and stored?
Made in liver —> stored in gallbladder
How does bile enter the SI?
During a meal, the gallbladder contracts and sends bile into SI
What is the function of bile?
Aids in digestion of fats and elimination of waste products from the blood
What are the primary responsibilities of the Jejunum and ileum?
for absorption of nutrients into the bloodstream that are used for energy, growth, and cell repair
Which part of the SI is more vascularized?
The jejunum - the presence of the villi increase the surface area allowing the greatest absorption here
Where does the greatest amount of absorption happen?
Jejunum
How long does it take chyme to travel through the small intestine?
24 hours
What is left after absorption in small intestine?
Waste is left and passed dot the large intestine through the ileocecal valve and cecum on the right side of the trunk
Large intestine/colon details:
- 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
What is the human microbiome?
The total DNA content of microbes inhabiting our bodies. Composed of: - bacteria - archaea - fungi - viruses - Protozoa - Eukaryotic microbes
Gut microbiome function
- 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
Healthy adult humans typically harbor ________ species of bacteria
More than 1000
