A&P - Chapter 39 (Part 1) Flashcards
What is the main digestive system organ?
Small intestines
Where does the small intestine go from?
Pyloric sphincter
to the ileocecal valve
How long is the small intestine?
6-8m long
- 2.5cm in diameter
What are the 3 divisions of the small intestines?
- Duodenum
- Jejunum
- Ileum
What is the small intestine lined with?
Mucus membrane that is highly adapted for secretion
What are the lining of the small intestine adapted for? (2)
- Secretion
2. Nutrient
Plicae
Multiple circular folds
What is plicae covered with?
Villi
What does villi contain?
- Blood capillaries
- Lymph lacteals
- for nutrient absorption
What cells are on the microvilli of the small intestines? (3)
- Mucus-secreting cells,
- Enteroendocrine cells
- Tuft cells
What is villi covered by?
Microvilli
- brush border
What do villi and microvilli do?
Increase the surface area of the small intestine hundreds of times
Where is the intestinal crypts located?
In the ‘valleys’ between villi
What does the intestinal crypts contain?
Stem cells (rapid mitosis) - from which the intestinal cell types are produced and then migrate upward to cover the villi, where they eventually slough off
What are stem cells pertected by?
Paneth cells
What do paneth cells produce?
Enzymes and other substances to control the growth of bad bacteria
What is the last part of the GI tract?
The large intestines
Large intestines
Smooth muscle fibres in wall contract for churning & peristalsis for ultimate evacuation of bowel
What do the muscus membrane of the large intestine do?
- Absorption of water
- Salts
- Vitamins
What do the large intestines not contain?
No villi
What do no villi allow for?
Less surface area/not well suited for absorption compared to small intestine
What are the 4 parts of the large intestines?
- Cecum
- Colon
- many divisions - Rectum
- Anus
Where is the cecum located?
At the ileocecal valve
What are the 4 divisions of the colon?
- Ascending colon
- Transverse colon
- Descending colon
- Anus
How long is the rectum?
17-20cm
Rectum
Holding tank before exiting the body
Anus
Opening to exterior
What are the 2 sphincters of the anus?
- Inner anal sphincter
2. Outer anal sphincter
What kind of muscle is the inner anal sphincter?
Involuntary
What kind of muscle is the outer anal sphincter?
Voluntary
