Lecture 20 -- review questions Flashcards
which region of the small intestine receives the chyme?
duodenum
which region of the small intestine receives the pancreatic juice and bile?
duodenum
what is the main function of the duodenum?
acts as mixing bowl
–> neutralize acidic chyme
how is the acidic chyme neutralized in the duodenum?
duodenal glands secrete bicarbonate-rich mucus
–> neutralizes stomach acid
–> inactivates pepsin
–> stops protein breakdown
in which part of the small intestine does most nutrient digestion and absorption occur?
jejunum
what is the function of the ileum?
absorb Vitamin B12
reabsorb bile salts
what are Peyer’s patches, and where are they found?
lymphoid follicles, mainly comprised of B-cells
found in jejunum and ileum
what is the ileocecal valve (ileal papilla), and where is it found?
sphincter that controls flow from ileum (small intestine) to cecum (large intestine)
ileum (sm intestine) –> cecum (lar intestine)
where is the pyloric sphincter found? what does it control?
pyloric sphincter
stomach –> duodenum
controls passage of chyme from stomach to duodenum of small intestine
which 2 types of motility does the small intestine have?
peristalsis – slow-propulsion
segmentation – promotes mechanical breakdown and mixing of chyme w/ digestive juices and bile
what common advantages do circular folds, villi, and microvilli provide to the digestive process?
increase surface area of small intestine that promote digestion and nutrient absorption
what 3 structures increase the absorptive surface area of the small intestine?
circular folds
villi
microvilli
what 2 kinds of epithelial cells cover a villus?
enterocytes – absorptive cells
goblet cells – secrete mucus
what can you find inside of a villus?
lacteal –> lymphatic capillary
blood capillaries
vein
artery
what is another name for absorptive cells?
enterocytes
what is another name for intestinal glands?
intestinal crypts
what makes up the brush border in the small intestine?
microvilli
what are the 5 major types of cells found in the mucosal epithelium of the intestinal crypts?
(1) enteroendocrine cells
(2) stem cells
(3) paneth cells
(4) enterocytes
(5) goblet cells
what is the role of the enterocytes covering the villi in the small intestine?
absorbe nutrients and electrolytes
what is the role of the enterocytes covering the crypts in the small intestine?
secretion of the intestinal juice (water w/ mucus)
what 2 factor stimulate the secretion of intestinal juice by the enterocytes?
hypertonic and acidic chyme
hypertonic – from high [ ] of solutes coming from stomach
acidic – from low pH from stomach
where are Paneth cells found?
bottom of intestinal crypts
what do Paneth cells release?
release antimicrobial agents
what organ secretes the hormones CCK and secretin?
enteroendocrine cells in the small intestine
what are the 2 main functions of the large intestine?
absorb important vitamins generated by bacterial action
absorbs water and compact intestinal contents into feces
why does the large intestine have a vast number of goblet cells?
large intestine needs to have a lot of mucus
- ease passage of feces
- protects the intestinal wall from irritating acids and gases released by resident bacteria
what are the regions of the (small and large) intestines in order?
duodenum
jejunum
ileum
cecum
ascending colon
transverse colon
descending colon
sigmoid colon
rectum
anal canal
where is the (vermiform) appendix located?
attached to the cecum
what is taenia coli?
3 bands of longitudinal muscle in muscularis –> shorter than large intestine –> cause large intestine wall to pucker –> make pocket-like sacs (Haustra)
where does taenia coli come from? (specific layer of the wall)
muscularis externa layer (longitudinal muscle) of the large intestine
where are the taenia coli found in the digestive tract? (organ)
large intestine
where are haustra found in the digestive tract?
large intestine
what forms haustra in the large intestine?
taenia coli are shorter than large intestine but run along walls of larger intestine
–> pucker the muscularis externa layer of the large intestine
what are Omental appendages?
sacs of fat in the serosa
where are Omental appendages found in the digestive tract?
serosa
what are haustral contractions, and where are they produced?
segmentation (churning) in the large intestine
what is the function of haustral contractions?
bring chyme in close contact with mucosa to maximize water, electrolyte absorption
which stimulus promotes haustral contractions?
distension of a haustrum with feces stimulates it to contract
–> passes the residue distally to another haustrum
what are “mass movements,” and where are they produced?
slow, powerful contractions that move undigested waste over large areas from colon –> rectum for defecation
what is the function of the mass movements or mass perstalsis?
move undigested waste over large areas from colon –> rectum for defecation
what sphincters are found in the anal canal?
which one can you control?
internal anal sphincter
external anal sphincter
you can control external anal sphincter
which type of muscle is the internal anal sphincter made of, smooth or skeletal?
smooth
which type of muscle is the external anal sphincter made of, smooth or skeletal?
skeletal
what is the anus?
exit of the anal canal
what is the gut microbiome?
over 800 species of enteric bacteria in the large intestine
consist of bacteria, fungi, parasites, and viruses
microbes that are both helpful and potentially harmful
what is the importance of the gut microbiome? (indicate their functions in the intestines)
prevent overgrowth of harmful bacteria by competing for nutrients
digest cellulose, pectin, and other plan polysaccharides that we can digest –> we absorb the resulting sugars
which organ of the alimentary canal contains the highest concentration of enteric bacteria?
large intestine
