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UKCD HIsto GI Glands
answers to GI gland test objectives
| Question | Answer |
|---|---|
| Name three major types of glands of the GIT based on their location/proximity to the lumen | Mucosal; submucosal; transmural. |
| What is the structural/functional unit of the exocrine pancreas? | The secretory acinus. |
| In what form are some of the enzymes released? Why? | As proenzymes activated only by intestinal compounds. It protects the pancreas from autodigestion. |
| What are zymogen granules? | Protein-based enyzyme granules. |
| What enzymes does the pancreas secrete? | Trypsinogen; lipase, amylase, etc. |
| Where is a centroacinar cell found? | Lining the exit region of the secretory acinus acting as the initial aspect of the duct lining. |
| State the function of a centroacinar cell. | They secrete a bicarbonate solution that neutralizes the acidity of the enzyme secreted by the acinus as well as dissolving them. |
| What is an intercalated duct and how do they differ from intralobular ducts? from interlobular ducts? | An intercalated duct drains an individual acinus. They differ from the other types of ducts by the fact they have only a low cuboidal lining and NO surrounding CT. |
| What is the structural/functional unit of the endocrine portion of the pancreas? | the islet of Langerhans (pancreatic islet) |
| Name three cells types found in these units and their location in the islet. | Alpha (A) cells found peripherally; the beta (B) cells found centrally; and the delta (D) cell also found peripherally. |
| What do alpha cell secrete and what is its function | glucagon that increase blood sugar levels |
| What do beta cells secrete and what is its function | insulin that lowers blood sugar levels |
| What do delta cells secrete and what is its function | somatostatin that inhibits both glucagon and insulin. |
| Where are alpha, beta and delta cells hormones secreted? | Into the capillaries (blood) within the islets. |
| How are blood sugar levels are regulated? | Glucagon is released w/ low blood sugar levels, causes liver cells to break down stored glycogen and release sugar, Insulin is released w/ high blood sugar levels, It causes the liver cells to take up sugar from the blood and store it as glycogen. |
| What is hypoglycemia? | Abnormally low blood sugar levels |
| From which two circulatory sources does the liver receive blood? | The portal vein and hepatic artery. |
| What is the function of the portal vein? | brings nutrient-laden blood from the G.I.T. to the liver for screening before it is released into the systemic circulation |
| What is the function of the hepatic artery? | brings oxygen-laden blood to the liver. |
| What is the structural/functional unit of the liver? | A lobule. |
| What are the three hypotheses for this str/fcn organization? | Classic lobule: hexagonal in shape using a central vein as the axis; Portal lobule: defunct; Liver acinus: a triangular area using two central veins as the extreme tips. |
| In what structures, and in which direction does blood flow through the classic lobule? bile? lymph? | Blood: flows throuigh the sinusoids from peripheral to central; Bile: flows through canaliculi from central to peripheral; Lymph: flows through the perisinusoidal space to lymphatics in the portal area (from central to peripheral). |
| What structures are found in a portal area? | Branches of the epatic artery, hepatic vein, bile ductule, lymphatic vessel. |
| Where are portal areas located? | At each of the six corners of the classic liver lobule. |
| How are the hepatocytes organized within the classic lobule? | As radiating plates of cells from the central vein outward to the periphery of the lobule. |
| Through what does the mixed arterial and hepatic portal blood flow? | The hepatic (liver) sinusoids |
| Where does the mixed blood end up within the lobule? | It empties centrally in the lobule into the central vein. |
| What two cell types line the hepatic sinusoids? | Endothelial cells and Kupffer cells |
| Where do bile canaliculi drain immediately, eventually? | Bile canaliculi drain to bile ductules at the portal areas and finally leave the liver in the right and left hepatic ducts (each draining a major lobe of the liver). |
| What keeps bile from leaking out of the canaliculi? | These cell membrane channels are sealed by continuous tight junctions |
| Where is the perisinusoidal space (of Disse)? | The space between the back of the liver sinusoid and the hepatocyte cell membrane. |
| What forms in the space of disse (perisinusoidal space)? | Lymph, and lots of it. |
| What is a Kupffer cell? | A “fixed” macrophage |
| Where are these cells found? | In the lining of the liver sinusoids |
| What is the space of Mall and where is it located? | the space of Mall connects the perisinusoidal space (of Disse) to a lymphatic vessel in the portal area of the liver. |
| What is the canal of Hering and where is it located? | The canal of Hering connects the bile canaliculi to the bile ductules of the portal reas. |
| What is the function of Kupffer cells? | The Kupffer cells filter the blood of particulate matter. |
| What is the function of the gallbladder? | To store and concentrate bile |
| What are structural differences between the gallbladder and other regions of the tubular GIT? | mucosa lacks a muscularis mucosae,single cell type in epithelial lining, no submucosa, muscularis is not continuous sheet of muscle but contains pockets of fibrous CT fibromuscular layer,exhibits serosa exposed aspect and an adventitia attached to liver |
Created by:
wiechartm
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