Digestive System Part II Flashcards
1
Q
The Small Intestine
A
To exact nutrients from the chyme coming in
- Duodenum - 5% of length of small intestine - digest the chyme coming in
- jejunum - 30-40% Extract nutrients from foods coming in
- Ileum - 55% Anything that hasn’t been dissolved by the jejunum (vitamins, some bile salts, and a lot of water)
What atery is supplying the small intestine?
- Superior mesenteric artery - supply all small intestine and 2/3 of large intestine
2
Q
Small Intestine
What is the purpose of circular folds and villi?
A
- What is the purpose of circular folds and villi?
- slow down the fluid however if we grooves around the fluid will run in a circular pattern
- the villi purpose to increase surface area along with the microvilli to increase contact w/ chyme to be able to pull the nutrients out
- Microvilli brush border all along the surface area of the cell we’ll have enzymes (breaking down sugars into glucose, individual amino acids, then smaller lipids purpose we’re not able to take up large molecules through cells) and transporter (can’t take up big molecules) like glycogen. So we have enzymes embedded in the plasma membrane that work to break down complex sugars (multiple sugars) into individual glucose molecules then transporter proteins in the plasma membrane and take up sugar molecules transport through the cell and get them through the blood vessels. Similar to Polypetides
- Lipids can move through plasma membrane
- Arteries to supply fresh oxygenation and veins are going to head into these veins and heading to the jepatic portal vessel (liver)
- how? move through the venous vessels that rise up within the villi then go to these larger vessels
- Fats will be transported into the lymphatic vessels (green) and the lympathics will go into larger vessels, bypass the liver, ultimately put them into the venous blood supply (not processed in the liver)
3
Q
Small Intestine
A
- Absorptive enterocytes (have microvilli and simple columnar) their purpose is to pull nutrients in
- Lacteal - piece of lymphatic rises up within the villus so all lipids are going into the lacteal
- Globet cells - mucus producing cells help east things as they’re sliding past
- MALT - taking in all sorts of bacteria that live in large intestine so we need immune defenses
- Crypts - producing a watery fluid and water will mix some of the chyme that helps dilute the acid we see with the chyme
- Muscularis mucosa incase anything gets stuck and to flick away
What organelle might be especially prevalent in absortive enterocytes?
- mitochondrias - powering all the transporters and sugars, amino acid into the cells.
- Smooth endoplasmic reticulum - process the fats that are moving into the cell
4
Q
- Pancreas
A
- Not part of alimnetary canal important for digestion bc of different enzymes
- both an endocrine (the products are secreted into blood) cells that make both isulin (lower blood sugar) and glucogon (elevate blood sugar) and exocrin gland make products that are secreted into ducts
- Pancreatic duct
- tail of pancreas is right next to where the spleen would be
- produces trypsin, which break down peptides
- lipase which break down fats
- release amylase which break down carbohydrates
- So the cells make this within the pancreas will release into small ducts that then join up with the main pancreatic duct (runs through the pancreas all the way to the hepatopancreatic ampulla and sphincter) also a sphincter on the end of this main pancreatic before it gets to hepatopancreatic sphincter
- main source for digestive enzymes from the pancreas to head into the duodenum (chemical digestive piece)
- So Ampulla is where all those enzymes will enter into also a piece joined up with common bile duct (green)
- bile is compound made by liver and stalled in the gallbladder
- bile and join up at the hepotopancreatic ampulla (shared entry way)
- if the hepotopancreatic ampulla gets blocked there’s the accessory pancreatic duct that some enzymes from the pancreas can head into - the enzymes are so potent they can start to digest the pancreas itself which isn’t good. Inflammation, pancreatitis
- Can make 22 different types of enzymes
5
Q
Pancreas
A
- Acinar cells contain all little zymogen granules these vesicles full of the enzymes that are producing and what will happen is those zymogen granules will end up given a signal, hormonal signal they’ll end up fusing w/ the cell membrane and those enzymes will be released into the actual lumen of the duct all the small lumes will join into the larger main pancreatic duct
- What organelle high concentration within the acinar cells?
- Mitochondria - active transport process
- Rough ER -
- Lots of Golgi - packaging and shipping
6
Q
Liver
A
- processing all the nutrients that our absorptive enterocytes rather than enteroendocrine cells
- Larger right lobe and smaller left lobe - sits upper right quadrant of the abdomen separating the two lobes are the falciform ligament (ventral mesentery)
- Cuadate lobe - heading posteriorly towards the inferior vena cava
- Quadrate lobe heads anteriorly and sits betwn the falciform ligament and the gallbladder
-
Teres ligament - the remnant of the umbilical vein - brings nutrients to the infant
- after the umbilical cord is cut off it’s called the ligamentum teres
- Porta hepatis - gate or portal to liver similar to the hilum in the lungs
7
Q
Liver
A
- Hepatic arter coming off the common hepatic artery that’s heading into the liver
- Portal vein bring all the nutrients from the small intestine are draining into liver
- Left and Right heptaic ducts which are gonna feed into the common bile duct
- ^whole are called the Porta Hepatis
8
Q
A
- More than 500 known functions of the body
- Produces biles emulsifier coming down bile duct first made by cells in both left/right lobes as well as caudate and quadrate and filter into right/left hepatic ducts fuse together to form common hepatic duct branch cystic duct will head into the gallbladder and when we need it. Joining of hepatic and cystic duct is the common bile duct will bring bile down to the heptopancreatic ampulla to empty into our duodenum
- Produces cholesterol
- Detoxifies drugs and alchohol metabolize those drugs into things that are not toxic for us and the toxic byproducts that are released into the blood will get filtered out by the kidneys also detoxifying alcohol
- Destroys old RBC’s - if spleen’s remove the liver will take over it’s job\
- producing clotting factors so if we cut ourselves we don’t bleed out
- Metabolizing hormones - if hormones are released in body we don’t want them to activate receptors forever
- Secretes IGF-1 hormone which is growth along with growth hormone
- Secrete a molecule angiotensinogen - important for blood pressure
9
Q
Hepotocytes
A
- Livercells
- Smooth ER
- Rough ER
- Peroxisomes - dexification of drugs
- Mitochondria to power all processes
- Golgi apparatuses to help pump out
- lysomes to break down the hormones
- liver stores glycogen sugar source for our body so we’ll have lots of glycosomes
10
Q
The Liver’s Role in Digestion
A
- hepatic portal vein is not an actual vein in sense it takes blood back to the heart but it is taking blood supply away from the small intestine . Nutrient rich blood into the liver but mostly deoxygenated
- Coming out of the liver is the Hepatic Vein - isn’t as much nutrient supply in hepatic vein which joins with our inferior vena cava.
- Convert glucose into glycogen for stoage
- Covert glucose to triglycerides which is fat source of the body
- Breaks down amino acids into urea which gets filtered out by the kidney and triglycerides
11
Q
In the liver
A
- Lobules
- Portal Triad
- bile duct - collecting bile made by all the cells and bringing them out
- portal venule - bringing in nutrient-rich blood from our portal vein
- portal arteriole - branch of the hepatic artery - bringing oxygen rich blood in
- Portal Triad
- In between liver cells (green tubes) Bile canaliculi - little canals enter into bile ducts and which will feed into the left/right hepatic duct then common bile duct along with the cystic duct
- Oxygen rich blood and nutrient rich blood and feed into the fenestraded sinusoid (twisty curve blood vessels blood moving very slowly, we want the nutrient rich blood move through slowly so the cells can pull the nutrients out and process them as appropriate whether that’s to store glucose as glycogen or to break down an amino acid into another storage form and waste product
- the sinusoid will empty into a central vein
- Lobule has a central vein in the middle that central vein from each lobule will join w/ interlobular vein which head to the hepatic vein feeds into the inferior vena cava taking blood back to the heart
- Stellate macrophages - gobble up any type of pathogens and plays a role in breakdown any old red blood cells especially if Spleen is removed the macrophages will take over to remove the red blood cells
- Plates of hepatocytes - are made of many different hepatocytes all organized in rows, w/ sinusoidal capillaries running betwn the rows
12
Q
Cirrhosis of the Liver
A
- Long term damage/scarring of liver
- Caused by hepatitis, alcohol, and fatty liver disease
- If we have too much dense conntective tissue that takes over (fibrotic tissue) we’re gonna block all of those different passageways, block bile canaliculi, sinusoid and the fuction won’t be able to make bile and secrete it or process all the nutrients
- During liver transplant can take 60%-70% of liver and donor is left with about 30%
- within 4-6 weeeks they’re liver will regenerate to 100%
13
Q
Gallbladder
A
- Accessory organ
- Sits underneath the right lobe of liver
- Stores and concentrate bile -simple columnar cells to pull some water to concentrate it
- Rugae- has mucosal folds to expand or contract to hold more bile
- Connected to this common hepatic duct via cystic duct
- Liver will produce the bile. The bile will come from the left and right hepatic duct and travel down the common hepatic duct but if we’re not digesting any our pancreatic duct and hepatopancreatic ampulla, sphincter are going to close as a result the bile comes down and hits a dead end and reflux back up the common bile duct and this time head into the cystic duct and then stored into the gallbladder
- Bile will move through the ducts via peristaltic waves just like what we had that are moving through the rest of teh alimentary canal
14
Q
Clinical Correlate: Gallstones
A
- Crystallization of cholesterol
- Cholesterols made by the liver
- break down product of hemoglobin called bilirubin these will make up the bile
- Blockage of common hepatic or bile ducts prevents bile from entering small intestine
- Crystals will start to move down the cystic duct and into the common bile duct. They will block the passageway so no more bile can move through
- That will cause a problem for digestion for emulsifying those fats that we’re consuming but it will also cause a problem for all excess bile being made and the bilirubin from the bile that will back up into the liver and ultimately end up in the bloodstream that we need to get rid of so it ends up in the skin and bilirubin has a yellow color to it so ppl have jaundice
- Bilirubin which component of bile they get a backlog of that into their skin in the sclear of the yes and it’s a result of either bile not being able to move down through the ducts due to blockage from a gallstone; it could also be due to cirrhosis of the liver
- Taking care of issues with liver, sunlight can help
- Treamtments: cholecystectomy surgical removal of the gallbladder, (don’t need it to live) and your liver will constantly make bile and sending it down the common bile duct may result in running stool.
- medication that work to disolve the gallstones
- Lithotripsy using sound waves that shoot through the skin the gallbladder and break apart the soundwave (varying efficacy)
- lithotripsy
15
Q
Large intestine
A
- Receiving feces from our ileum (last part of small intestines)
- Ileocecal valve
- When feces comes in and fills up the first part of the large intestine called the cecum (right side of abdomen) that reflexive stratch will close the valve and prevent further feces from moving in until we move the feces along
- Feces will move up to ascending colon and then into the transverse colon which runs horizontally across our abdomen (right side of abdomen)
- Superior mesenteric artery supply first half of our large intestine as well as small intestine
- Covered with our greater omentum hanging down over the top
- Appendix which is branching off of the cecum right here - contains some bacteria that’s benefical for us
- Role to pull out water - it’s to dehydrate the feces so that it becomes the stoll you are defecating out
- No circular folds, no villi and microvilli,
Resident bacteria within our large intestine helping to break down things that we were unable to breakdown and extract nutrients from that help ease the passage of molecules
- Feast on things we pass on there bacteria in the large intestines is what is causing the gas as a result of feasting on whatever for example lactose intolerant means you don’ have the enzyme in the small intestine that break fown lactose
- teniae coli - large piece of smooth muscle
17
Q
Hastrum
A
- large intestines have segments called hastrums
- each individual have own little pieces of smooth muscle within the walls
- As feces accumlates, it will cause some stretch of that haustrum and that will reflexively activate muscle that causes it to pass on the next haustrum and reflectively close the spincter betwn two adjacent haustra so it can’t move backwards
- Hasutral contractions move throuhg segment to segment all the way through
-
Large mass movements - large multi segment contractions of that longitudinal smooth muscle that will take the food residue, the feces, and move it multiple hasutra at a time
- routine when going #2
19
Q
A
- 2 muscles in anal canal
- Internal anul spincter - Involuntary
- When there is stretch within the anus that will cause reflecive relaxation of the internal anal spincter and normally feces want to come out however we have our external anal sphincter, which is voluntarily controlled if we are potty trained (circular muscles that helps close off the anus)
- Anul column contain blood vessels but also some mucosal glands so that when there is some stretch there they will reflexively release some mucus to aid in the feces moving through
- Levator ani muscle voluntarily controlled muscle when we contract it - it literally lifts up the anus around the feces sort of stays where it is and the anus will elevator to leave the feces outside of the body - helps to aid with defecation
- Rectum sits empty unless it’s time to defecate and those feces are in the sigmoid colon
- Also consist of these rectal valves - three of them
- serve as little flaps to allow gas to escape
- veins due to muscles - hemorrhodial veins like varicose veins that we talked about earlier with our venous system. They are engored veins where the valves have been bascially blown apart and so blood sort
- Engorment of veins with blood inside anus some of the external hemorrhoidal veins they’ll actually end up just - the main sign is not bleeding, painful or itchy
- can be removed
- What kind of tissue found in anus?
- Stratifed squamous epithelium
- alot of friction forces
- protective role
- Simple columnar - everywhere else beside esophagus and anus we’re going to find simple columnar epithelium to aid in more of the absorptive processses
