Module 2 Lecture 2 Part 1 Flashcards
What makes up the small intestine?
The small intestine is made up of the duodeum (25cm), the jejunum (2m) and the illeum (3m)
Why is the small intestine important?
The small intestine is important for digestive and absorptive functions (carbs, proteins and fats), also there are secretions and buffers provided by the pancreas and the gall bladder (live)
Where does digestion begin?
begins at the pyloric sphincter (stomach/small intestine transition) and ends at the Illeocecal valve (small intestine/large transition)
Label the parts of the small intestine
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What is the duodenum and what is its function?
the duodenum is a c-shaped tube, it is a mixing bowl - for chyme with bile and pancreatic secretions, it originates from the pyloric sphincter. The retroperitoneal apart from the most proximal part which is intraperitoneal
Label the pancreas
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Where does bile and pancreatic juice enter?
Bile and pancreatic juice enters the duodenum via the major duodenal papilla
What is the jejunum?
• Important digestive and absorptive functions (carbohydrates, proteins, and fat) • Begins at the duodeno-jejunal flexure (junction) and has no clear anatomical boundary with ileum • Intraperitoneal suspended by the mesentery proper
What is the illeum?
• Absorption of vitamin B12; salts and all products of digestion that were not absorbed by the jejunum • Intraperitoneal suspended by the mesentery proper
Where does the illeum end?
The illeum ends at a sphincter, the ileocecal valve, which controls the flow of materials from the ileum into the cecum of the large intestine
What are circular folds (plicae circulares)? and what do they do?
Plicae circulares increase surface area for absorption and to slow the passage of food, all parts of the small intestine contains plicae (circulares): circular folds of the intestinal lining
What are plicae?
Plicae are duplications of the mucous membrane, the transverse folds of the intestinal lining; increase intestinal surface area 3-fold
Where do plicae appear?
The appear in the duodenum and the jejunum prominently and becomes less common in aboral illeum
What are villi?
Villi are finger-like projections of the mucosa; increase intestinal surface area by 30- fold
What are micro-villi?
fingerlike structures on intestine cells; increase intestinal surface area 600-fold
Label all plicae and villi
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Where is the large intestine located?
Lies around the edges of the abdominal cavity and is
supported by the mesocolon
What is the large intestine consisted of?
The large intestine is consisted of 4 colons (ascending, transverse, descending and sigmoid)
What is the function of the large intestine?
The large intestine absorbs water and electrolytes from the remaining digested material to solidify into feces, there is no villi present and it stores fecal matter until defecation.
Label the large intestine
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What is the Caecum?
The caecum receives chyme from the ileum, mostly intraperitoneal
What is the appendix?
The appendix contains lymph nodes and is intraperitoneal
What is the descending column?
The descending column is retroperitoneal
What is the sigmoid colon?
The sigmoid colon consists of the sigmoid mesocolon, it is intraperitoneal
What is the rectum?
The rectum is a retroperitoneal muscular tube, it stores feces prior to defecation
Label the colon
What are the features of the colon?
The ileocecal valve, the appendix, the hasutra ( sacculations -roles) and tenia coli
What is the anus consisted of?
- Internal anal sphincter
- Composed of a ring of smooth muscle
- External anal sphincter
- Composed of a ring of skeletal muscle
What is Cholecystokinin (CCK)?
The cholecystokinin (CCK) peptide hormone is secreted by the duodenum and jejunum, in response to food in the alimentary tract. The main stimulator for the secretion is the release of food - particularly fatty food - from the stomach into the duodenum. ▪CCK triggers the release of bile, made and released in the liver but stores in the gallbladder --> breaks down fatty acids
Label accessory digestive organs
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What is the liver?
The largest visceral organ (1.5-2kg) ➢ It sits underneath the diaphragm ➢ Essential for survival ➢ It is covered by connective tissue capsule and visceral peritoneum (NOT the bare area)
Label the liver
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What are the functions of the liver?
To remove and add compounds to the blood as it circulates through the
lobule
What are the functions of the liver (secretion)?
• secretes plasma proteins & bile • bile (water, ions, bile salts) • water & ions dilute & buffer the acids in the chyme as it enters the SI • aids in digestion of fats
What are the hematological regulation functions of the liver?
the largest blood reservoir (25% of cardiac output) • phagocytic cells remove cellular debris and pathogens from circulation • liver cells synthesise plasma protein
What are the metabolic functions of the liver?
blood from the GI tract enters the liver via the hepatic portal system • liver cells extract nutrients or toxins, from the blood before it reaches systemic circulation • liver cells monitor and adjust the levels of metabolites • toxins and metabolic wastes are removed for inactivation and secretion • absorption of fat soluble vitamins (A, D, K, E)
What are the blood supplies in the liver?
2 blood supplies: one venous and 1 arterial
What are portal veins? label where they are!
Portal veins contributes 75% of the
blood volume of the liver (rich in
nutrients-poor in oxygen)
What are hepatic arteries?
Hepatic artery contributes 25% of
blood volume entering the liver (rich
in oxygen-poor in nutrients)
Does blood in the portal veins and the hepatic arteries mix?
Blood from the portal veins and the
hepatic artery mix as it enters and
passes through a liver lobule.
After the blood mixes, where is it collected?
Then the blood is collected by the
hepatic central vein. The hepatic vein
carries 100% of the blood out of the
liver and into the inferior vena cava.
Label the liver, anterior and posterior
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What does the falciform ligament do?
The falciform ligament is a peritoneal fold that secures the liver to the abdominal wall)
Hepatic veins deliver?
Hepatic veins deliver oxygenated blood into the inferior vena cavaq
Hepatic arteries deliver?
Hepatic arteries provide oxygenated blood to the liver
What is the lesser omentum?
- spans between the liver and the lesser curvature of the stomach
- contains the veins/arteries of the liver & stomach as well as the bile duct
- can be viewed as the mesentery of the liver and stomach
What does the gallbladder do?
Concentrates bile produced by the liver and stores it until it is needed for digestion (40-60 milliliters) provides nerve supply Parasympathetic: contracts of gall bladder • Sympathetic: relaxes gall bladder
What does the cystic duct do?
The cystic duct connects the
gallbladder to the common
bile duct - to secrete bile into the duodenum
Where is the pancreas located?
Head: Curve of the duodenum
Tail: extends to the spleen
▪Retroperitoneal organ
What are the functions of the pancreas?
Endocrine: Production of insulin and glucagon,
which regulate blood glucose levels and are
secreted into the blood stream
Exocrine: Production of pancreatic juice
(enzymes), secreted in the duodenum; lipases
(lipid digestion); amylases (starch digestion);
proteases (protein digestion)
Label the pancreas!
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What does the main pancreatic duct deliver?
The main pancreatic duct delivers pancreatic juice, which drains into the duodenum. • Parasympathetic (vagus nerve) activity stimulates pancreatic juice secretion. • Sympathetic activity inhibits pancreatic juice secretion.