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Anatomy 3222 - Week 9: Accessory Digestive Organs

Terms in this set (95)

what is the role of the accessory digestive organs?
they aid in chemical digestion of food in the small intestine
what is the the role of the liver?
processes nutrients, secretes bile
what is the role of the gallbladder?
concentrates and stores bile
what is the role of the pancreas?
secretes essential digestive enzymes
true or false: the liver is the largest internal organ and the heaviest gland of the body
true
where is the liver located?
inferior to the diaphragm, almost entirely within the rib cage
what are the 2 lobes of the liver?
left and right
how are the left and right lobes of the liver divided?
divided by the falciform ligament
which of the two lobes of the liver is bigger?
right = large
left = small
true or false: the liver has poor vascularization
false, the liver is highly vascularized
how many supporting ligaments does the liver have?
2
what are the names of the supporting ligaments of the liver?
coronary and falciform ligaments
what is the falciform ligament?
a mesenteric fold that extends from the undersurface of the diaphragm, between the two lobes of the liver and the superior surface
what is the role of the falciform ligament?
helps to suspend the liver within the abdominal cavilty
what is the ligamentum teres?
the ligamentum teres/round ligament: the free border of the falciform ligament at the bottom
-a fibrous cord that is a remnant of the umbilical vein of the fetus (extends from the liver to the umbilicus)
what are 2 other lobes of the liver? and are they considered to be part of the left or right lobe?
-caudate and quadrate lobes
-part of the right lobe
what are the 4 primary functions of the liver?
-production and secretion of bile
-carb metabolism to maintain normal blood glucose
-store fat-soluble vitamins (A, D, E, K) and iron and copper
-remove toxic substances (ex. alcohol)
what is the name of the structure responsible for producing bile in the liver?
hepatocytes
how much bile can the hepatocytes generate per day?
up to 1L/day
where is bile stored?
gallbladder
how does the liver assist in maintaining normal blood glucose?
the liver can breakdown glycogen into glucose
what is the hepatic portal system?
a unique way the blood flows through the digestive system, to pick up nutrients from the stomach and intestine and deliver them to the liver for processing and storage
what are the 2 sources from which the liver gets blood? and what do each of the blood systems deliver?
-hepatic A: oxygenated blood
-hepatic portal vein: deoxygenated blood and nutrients, drugs, microbes and toxins from the GI tract
what is the flow of blood to the liver and then the heart?
hepatic A and hepatic portal vein come together and the hepatic sinusoids --> central vein --> hepatic vein --> inferior vena cava --> right atrium of the heart
what happens at the hepatic sinusoids?
this is where oxygen and most of the nutrients and then certain toxic substances are taken up by the hepatocytes
-the products manufactured by these hepatocytes, nutrients needed by other cells, are then secreted back into the blood
-this then drains into the central vein
what 2 veins merge to form the hepatic portal vein?
-union of the superior mesenteric vein and splenic vein
what is the hepatic portal vein specialized for?
-specialized to pick-up nutrients from the stomach/intestine and delivers to the liver for processing and storage
what is the simple role of the liver?
cleanses the blood
what are the contents of the portal triad?
portal vein, hepatic artery, common bile duct
what are the 3 types of the cells in the liver?
hepatocytes, bile canaliculi and hepatic sinusoids
what is the name of the functional unit of the liver?
liver/hepatic lobule
what is the shape of the hepatic lobule?
hexagonal shape structure
what are the internal structures in the hepatic lobule?
-central vein in the middle
-hepatic sinusoids and hepatocytes all around
true or false: the hepatic sinusoids drain into the central vein?
true
where does the portal triad exist within the hepatic lobule?
at 3 corners
what is a hepatic plate?
a section of the hepatic lobule
... a hepatic lobule is made up of many hepatic plates
how thick is a hepatic plate?
1-2 hepatocyte cells thick
what separates hepatic plates?
separated by capillary spaces (sinusoids)
what are stellate reticuloendothelial (Kupffer) cells?
-modified macrophages with the hepatic sinusoids
what is the role of stellate reticuloendothelial (Kupffer) cells?
-destroy worn out RBCs and WBCs, bacteria and other foreign matter in the venous blood that drains from the GI
-helps cleanse blood as it drains through the sinusoids to the central vein
what is the shape of the gallbladder?
pear-shaped sac
where is the gallbladder located?
located on the inferior surface of the liver
what is the role of the gallbladder?
stores/concentrates bile produced by the liver, until needing the duodenum of the small intestine
what are the 3 sections of the gallbladder?
fundus, body, neck
describe the fundus of the gallbladder
-broad, at the bottom, below the inferior border of the liver
-projects inferiorly
describe the body of the gallbladder
-central
-project superiorly
describe the neck of the gallbladder
-tapered
-projects superiorly
where is bile produced?
in the liver
draw bile flow chart
...
what sphincter controls bile flow into the small intestine?
the heptopancreatic ampulla sphincter
what changes with the bile flow between meals?
the hepatopancreatic ampulla sphincter closes because bile is not needed
how does bile flow return following a meal?
-after a meal, many neural and hormonal stimuli promote the production and release of bile
-fatty acids, amino acids, fats and proteins in the chyme enter the duodenum and stimulate duodenal endocrine cells to release CCK into the blood
what is the role of the CCK wrt the gallbladder?
-causes contraction of the walls of the gallbladder, which squeezes out the stored bile into the cystic duct, into the common bile duct, and into the dudenum
-causes the relaxation fo the sphincter of the hepatopancreatic ampulla allowing bile to flow into the duodenum
what causes the production of gallstones?
-if the bile has insufficient bile salts or excessive cholesterol, the cholesterol may crystallize to form bile stones/gallstones
what are the 3 places that gallstones can block from the gallbladder to duodenum?
-in neck or cystic duct
-within the gallbladder
-in common bile duct
what % of gallstones are symptomatic?
~10%
what are the symptoms of gallstones?
-sudden, severe pain in the upper abdomen
-inflammation without an infection
what is the acute treatment of gallstones?
-gallstone dissolving drug
-shock wave therapy
what is the chronic treatment of gallstones?
gallbladder removal
where is the pancreas located?
-retroperitoneal organ that lies posterior to the greater curvature of the stomach
what are the 3 sections of the pancreas?
head, body, tail
where is the head of the pancreas located? what does it also include?
-at the curve of the duodenum
-contains uncinate process which surrounds the superior mesenteric artery and vein
true or false: the pancreas is connected to the duodenum?
true, by 2 ducts
what are the exocrine cells of the pancreas called?
pancreatic acini
what are pancreatic acini formed of?
small clusters of glandular epithelial cells
what is the role of the pancreatic acini?
the cells within the acini secrete a mixture of fluid and digestive enzymes called pancreatic juice
how much digestive juice is secreted daily by the pancreatic acini?
secrete >1L of digestive enzymes/day
what does the pancreatic juice digest?
digests starches, proteins and triglycerides
what % of the pancreas is made up of acini?
99%
what are the endocrine cells of the pancreas called?
pancreatic islet
what is the role of pancreatic islets?
release insulin, glucagon, somatostatin and pancreatic polypeptide
what % of the pancreas to pancreatic islets make up?
1%
what is the general flow of the ducts through the pancreas?
pancreatic secretions will pass from the secreting cells in to small ducts, then into 2 larger ducts, and then into the duodenum
what are the 2 large ducts in the pancreas? and which one is larger?
1. pancreatic duct (larger)
2. accessory duct (smaller)
what is the flow of the pancreatic duct?
joins with the common bile duct from the liver and gallbladder and enters to duodenum as the hepatopancreatic ampulla
what is the flow of the accessory duct?
-flows from the pancreas, directly into the duodenum
-enters the duodenum above the hepatopancreatic ampulla by ~2.5cm
how is action of the pancreas regulated?
controlled by CCK and secretin released by the small intestine
what is CCK?
cholecystokinin
what is the role of CCK wrt the pancreas?
-release in response to protein and fat
-targets acini cells to release enzyme-rich pancreatic juice
what is the role of secretin wrt the pancreas?
-released in response to HCl
-stimulates the production of bicarbonate-rich pancreatic juice in the small intestine
what is pancreatic juice?
-clear, colourless liquid consisting of mostly water, some salts, sodium bicarbonate and several enzymes
-slightly alkaline pH because of sodium bicarbonate
why is it important that pancreatic juice is slightly alkaline?
this buffers the acidic gastric juice in chyme, stops the action of pepsin from the stomach and creates the proper pH for the action of digestive enzymes in the small intestine
what is the blood supply of the gallbladder?
branches of the hepatic artery (common hepatic artery)
what is the blood supply of the pancreas?
-splenic artery supplies the body and tail
-superior mesenteric artery supplies the head and neck
how is the body divided into quadrants
via 2 planes:
1. transumbilical plane
-through umbilicus
-at the level of intervertebral disc of L3/L4 vertebrae
2. median plane
-runs longitudinal through body generating right and left halves
what are the names of the 4 quadrants?
-right upper quadrant
-left upper quadrant
-right lower quadrant
-left lower quadrant
what are the contents of the right upper quadrant?
• Liver (right lobe)
• Gall bladder
• Duodenum
• Pancreas (head)
• Right kidney
• Right adrenal gland
• Hepatic flexure (right turn in large intestine)
• Transverse colon (right half) (large intestine)
what are the contents of the left upper quadrant?
• Liver (left lobe)
• Pancreas (body, tail)
• Left kidney
• Left adrenal gland
• Splenic flexure (left turn of left intestine)
• Transverse colon (left half)
• Stomach (most)
what are the contents of the right lower quadrant?
• Cecum
• Appendix
• Ileum
• Ascending colon (most) (large intestine)
• Right ovary
• Right uterine tube
• Right ureter
what are the contents of the left lower quadrant?
• Sigmoid colon
• Jejunum (small intestine)
• Descending colon (most) (large intestine)
• Left ovary
• Left uterine tube
• Left ureter
what are the overall results of aging in the digestive system?
• Decreased secretions
• Decreased motility
• Loss of strength and muscle tone
• Diminished response to pain and internal sensations
what are the effects of aging on the upper GI tract?
• Reduced sensitivity to mouth sores
• Loss of taste
• Periodontal disease
• Difficulty swallowing
• Peptic ulcer disease
what are the effects of aging on the small intestine?
• Duodenual ulcers
• Appendicitis
• Malabsorption and maldigestion
what are the effects of aging on the large intestine?
• Constipation
• Hemorrhoids
• Diverticular Disease
what are other results of aging on the digestive system?
• Gallbladder issues
• Jaundice, cirrhosis, pancreatitis
• Colon and rectum cancer, bowel obstructions
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