Digestive part two

What are the functional units of the liver?

hepatic lobules

What are the four main function of the large intestine?

-Absorbs water, bile salts, and electrolytes -absorbs vitamins such as B5,K and biotin -forms and stores feces -carries out defecation

Regulation of pancreatic secretions

-Acidic chyme stimulates release of secretin -secretin stimulates release of watery pancreatic juice with bicarbonate and phosphate - CCK and parasympathetic NS stimulates production and secretion of pancreatic enzymes and zymogens.

What stimulates the small intestine to increase its motility and secretion

-Mucus secretions, because of its presence of chime. -activation of the nerve plexuses -Gastroenteric reflex -Intestinal enzymes

Explain how pancreatic secretions are controlled

1 Acidic chyme enters the duodenum 2 interstitial mucosa releases secretin into bloodstream 3 secretin stimulates pancreas 4 pancreas release bicarbonate ion rich juices 5 bicarbonate ions neutralize, chyme

What are the parts of the large intestine? (You should be able to list these in order in which digested material passes starting from the cecum)

1. Cecum 2. ileocecal valve 3. Ascending colon 4. Transverse colon 5. Hepatic portal vein 6. Descending colon 7. Haustra 8. Sigmoid colon. 9. Rectum

What is the function of the pyloric sphincter?

A prevents food from entering into SI

Composition of bile

A yellow-green, continually secreted by hepatocytss

What are the four functions of CCK on the pancreas?

Act on gallbladder and contract it to release bile, act on pancreas and cause pancreas to contract and then release pancreatic juice, relaxes hepatopancreatic sphincter, and lastly contracts the pyloric sphincter that causes emptying of the stomach.

Describe the components of the portal triad?

At each of six corners of lobule, is a branch of hepatic artery, hepatic vein and bile duct.

What are gallstones

Bile contains calcium salts and cholesterol, both can precipitate and form hard lumps. These lumps are gallstones.

Portal venule

Blood vessel that carries blood from the gastrointestinal, track, gallbladder, pancreas, and spleen to the liver.

What stimulates the release of bile from the gallbladder

CCK

Small bile duct

Carries bile

Define and describe microvilli

Cellular membrane protrusions that increase the surface area for diffusion and minimalize any increase in volume

What is the main function of the small intestine?

Chemical digestion and absorption of nutrients

What is the purpose of proteolytic enzymes?

Continued breakdown of proteins that begin in the stomach

Through which ducts will bile from the pancreas on its way to the duodenum

Cystic duct, common hepatic duct, common bile duct and pancreatic duct.

What are the three segments of the small intestine and in which segment does most chemical digestion in nutrient absorption occur?

Duodenum, ileum and jejunum and the jenunum is where most absorption and chemical digestion occur

Between meals what stops pancreatic secretions from entering the small intestine, and destroying the intestinal wall.

Hepatopancreatic sphincter is closed it guards bile and pancreatic juice from entering the duodenum.

What prevents file from being released into the small intestine between meals?

Gallbladder

Where is bile produced?

Gallbladder

Paths of blood and bile in the hepatic lobule

Hepatic portal vein, sinusoids, central vein, hepatic vein, inferior vena cava

What is the enterogastric reflex?

Inhibits gastric activity and contracts pyloric sphincter.

What is rugae?

Interior of the stomach contains folds called rugae and it allows the stomach to expand considerably

The hepatic arterial

Is a short blood vessel, that supplies oxygenated blood to the liver, pylorus of the stomach, duodenum, pancreas and gallbladder

What is haustral churning and how often does it occur

It is mixing movements and it occurs every 30 min

What is the effect of CCK on hepatopancreatic sphincter and stomach emptying?

It relaxes the hepatopancreatic sphincter

What stimulates the movement of fecal matter into the anal canal

Mass movement.

Define the gastrocolic reflexes? Do they stimulate or inhibit motility through the alimentary canal?

Mass movements- usually follows meals, stimulate

Liver functions: three general categories of function

Metabolic regulation, hematological regulation, synthesis and secretion of bile (role in digestion)

What is the major movements of the large intestine? And what stimulates them

Mixing movements, Mass movements (stimulated by distension of stomach), and peristaltic wave from transverse colon.

List the functions of the stomach

Mixing reservoir, secretion of gastric juice, digestion, facilitates absorption of vitamin B, 12, secretion of gastrin and somatostatin.

Define and describe Villi

Mucosa folded into projections. It consists of a layer of enterocytes surrounding a central core of blood, capillaries and lymphatic vessel

What type of cells carry out digestion in the stomach and what are their respective secretions?

Mucus cells (goblet)- secrete mucus Chief cells (peptic)- secrete digestive enzymes, and Pepsinogen Parietal cells (oxyntic)- secrete HCI (parietal, pH) Endocrine cells- release histamine, serotonin, somastatin and gastrin

What action does the parasympathetic defecation reflects have on the internal and external anal sphincters ?

Note this reflex opens the internal sphincter and closes the external sphincter. Needs voluntary relaxation of the external sphincter for defecation.

What is the approximate PH at which pancreatic secretions function optimally? How is this pH achieved and why is it important?

PH of 8 high pH of pancreatic fluids helps neutralize acid chyme entering SI and provides optimal environment for intestinal and pancreatic enzymes

What is the pH of the empty stomach and what role does pH play in regulating activity of the stomach?

PH of an empty stomach is around 1.5 - 3.5. It activates activity of protein, pepsin, and as food enters the stomach dilutes the H C and the stomach becomes less acidic

Intrinsic Factor is from... and required for what vitamin absorbs

Parietal cells and vitamin B

What is the role of the stomach and vitamin B 12 absorption?

Parietal cells in the stomach secrete intrinsic factor, which is a glycoprotein required for B12 absorption in the SI.

Infants only have what gastric secretions

Rennin and gastric lipase

What stimulates the addition of bicarbonate ions in bile and pancreatic juice?

Secretin

What is chime?

Semi fluid pulp formed in the stomach made of partly digested food and the secretions of the gastrointestinal track

What type of epithelium lines the small intestine

Simple columnar epithelium

What type of muscle are the internal and external anal sphincter's?

Smooth muscle

Functions of secretin

Stimulates release of watery pancreatic juice with bicarbonate and phosphate. Causes the bile ducks to secrete bile rich in HCO3 .

What is the major blood vessel supplying arterial blood to the small intestine

Super mesenteric artery

What blood vessel supply the large intestine with arterial blood

Superior and inferior mesenteric arteries

What veins drain the large intestine into what vessel do these veins drain?

Superior and inferior mesenteric veins and they drain into the hepatic portal vein.

What problems will a person have if their gallbladder is removed

There is no place for bile to collect without a gallbladder, so bile releases directly into the small intestine.

What are chylomicrons and how are the absorbed into circulation

They are formed in the intestinal epithelia and they are surrounded by a shell made up of cholesterol, phospholipids and proteins. The function is the transport dietary triglycerides/ cholesterol

Define and describe the function of the plicae circulares

They are permanent, circular folds of mucosa, that further increase surface area for absorption, and they do not flatten out

Where do the veins of the small intestine drain?

This along with the splenic drain into the portal vein

pancreatic lipase

breaks down triglycerides

Three phases of stomach and what they do

cephalic- begin secretion and digestion gastric- enhances secretion and digestion intestinal- controls rate of gastric emptying and may slow emptying

Pepsinogen comes from

chief cells

Bile salts

derived from cholesterol, emulsify fats, absorption of fatty acids, cholesterol and vitamins.

pancreatic nucleases

digest nucleic acids

Bicarbonate ions

make pancreatic juice alkaline; buffer stomach acid, neutralize chyme

Hydrochloric acid is from

parietal cells

Gastric Secretions

pepsinogen, pepsin, hydrochloric acid, mucus, intrinsic factor

What is the livers role in digestion?

produce bile

Pancreatic Amylase

splits starch and glycogen into disaccharides, breakdown carbohydrates

Main function of the gallbladder

store and concentrate bile and release bile under CCK