BIOL&242 Name ______
Lab 38
This is a modified version of the original Lab 38 Handout. Please follow the instructions below. If a sketch is required, a space is provided for your work. This is all you need to hand in for Lab 38, no lab pages are required.
Esophagus
Human Esophagus, Total Magnification 100x
Label the above image of the esophagus with the six terms below (please label with JUST the letters). Labels will probably require brackets, to clearly show which region or structure is indicated (one bracket has been provided for you, as an example).
A.Mucosa B. Submucosa C. Muscularis externa
D. Stratified squamous epithelium E. Lamina Propria F. Muscularis mucosae
Q1:
The image above is from the superior one third of the esophagus, thus the muscularis externa is
a. skeletal muscle
b. smooth muscle
c. an equal mixture of skeletal muscle and smooth muscle
Esophagus and Stomach. Let’s first look at them together (they are connected you know!)
Here is a good, low power look at the esophagus-gastric connection, with description:
Here is a high power link, with description. Nice!
Hopefully in both images you noticed the abrupt change in the epithelium when moving from the esophagus (on the left) to the stomach(on the right). I also think the low power image is helpful in seeing the thickness of the muscularis externa.
Q2:Acid reflux (GERD) occurs HERE at this very junction, when gastric juices move “backwards” from the stomach into the esophagus. What protection from stomach acid does the esophagus NOT have, that the stomach has?
a. keratinized, stratified squamous epithelium
b. ample lymphatic tissue
c. a mucous membrane
d. goblet cells that make alkaline mucus
e. hair and natural flora
Stomach- Fundic region (fundus)
At 400x total magnification:
At 40x magnification:
Before you sketch the stomach lining, pause for a moment and “play along” with this “tour” of the stomach. Imagine you are very, very small--small enough to walk along the stomach wall surface. As you walk along the stomach, headed towards the small intestine, there is very little elevation change on your journey. Your walk is mostly flat, with gently, rolling bumps along the way (perhaps it looks a bit like the grey matter of the brain). As you walk, you must avoid falling DOWN, INTO holes. These holes lead down into gastric pits (which lead to deeper gastric glands). As you walk along, avoiding these pits, note that the pits are “bubbling” over with gastric juices and secretions.
Sketch and clearly label the fundusregion of the stomach.
-For the fundus, label: epithelia (what type), gastric pits, gastric glands, the thin muscularis mucosae, submucosa, and external muscularis layers. Indicate the area in the tissue where you expect to find parietal and chief cells.
Sketch here:
Q3: What do parietal cells secrete? ______
Q4: What do chief cells secrete? ______
Q5: What do G cells secrete? ______
Q6: Do rugae involve the submucosa or mucosa or both (submucosa AND mucosa)? ______
Here are some additional images of the stomach.
Small Intestine
The small intestine has three regions, the duodenum, jejunum and ileum. You have seen the ileum before- we looked at the ileum during the lymphatic lab to find Peyer’s Patches. So, since we have seen the ileum before, we will look at the duodenum and jejunum. You will only sketch the duodenum.
Before you sketch, imagine you are very small, once again. And now you are walking along the small intestinal wall. This journey is a very challenging one, one of endless climbing and descending. The wall is highly folded. And, protruding up from the folds are 400-500 million villi (you could think of each villus, singular, as a finger of a dishwashing glove). Then, each “finger” is lined by columar epithelium, with cells that have microvilli! (this is like covering the glove fingers with shag-carpet). Again, imagine trying to walk over the microvilli, of the villi, of the wall-folds!! Exhausting. The wall isn’t for climbing, it is designed to have maximal surface area to promote ABSORPTION of nutrients!
Links:
INDEX of unbelievably nice (and labeled) images- Digestive system. Start with the first “small intestine” link, and take a look around.
-For the duodenum, label: epithelia (what type), goblet cells (if you see any), intestinal crypts (also called the crypts of Lieberkuhn), Brunner’s glands (these are large glands of the submucosa, also called duodenal glands), and a villus. Although difficult to see, point/indicate where you would find a lacteal.
Q7: Why does the duodenal region of the small intestine have so many Brunner’s glands?
______
Q8: There is a large collection of lymph tissue (Peyer’s patches) in the ileum region that battles bacterial infiltration. Why is there likely to be bacteria here, in the ileum specifically, versus the jejunum?
______
Q9: Do plica involve the submucosa, mucosa, or both?______
Q10: What is in a lacteal? ______
More to look at- Jejunum- Ileum junction (with Peyer’s Patches)
Large intestine
Take a look around the colon (a portion of the large intestine) but you do not need to sketch. See the numerous goblet cells, and intestinal glands.
Q10: List all of the subdivisions of the large intestine: ______
______
Q11: Do you see villi here, in the colon? Yes or no? ______
Liver
Sketch and clearly label the liver. Identify and label (approximately) three lobules. For each lobule, label the central vein, portal area (hepatic triad), and hepatocytes. (look at second image)
Q12: What three vessels/ducts are present at the portal triad?______
Think about what fluid is found in each of the above vessels/ducts and which direction the fluid is traveling inside of these vessels.
Pancreas (yes, you’ve seen this slide before, so, no, you do not NEED to sketch it again, but you may want to take a look at it)
Recall that most of the pancreas is pancreatic acinar cells. The pancreas also contains pancreatic islets.
Q13: Which of these structures (acinus and pancreatic islet) is endocrine in function, which is exocrine?
______
Assorted last questions to answer:
Gland Matching – Match the gland from the right with the function/location on the left. Use each answer only once.
_____2. / Produce(s) a product containing amylase that begins starch breakdown in the mouth / b. gastric glands
_____3. / Produce(s) a spectrum of enzymes and an alkaline fluid that is secreted into the duodenum / c. intestinal crypts
_____4. / Produce(s) bile that it secretes into the duodenum via the bile duct / d. liver
_____5. / Produce(s) HCl and pepsinogen / e. pancreas
_____6. / Found in the mucosa of the small intestine; produce(s) intestinal juice / f. salivary glands
Q14. What is the gallbladder’s job? ______
Q15. What is the primary job of Kupffer cells of the liver? ______