Module 15: Digestive System II- Accessory Organs, Module 14: Digestive System I- Alimentary Tract

Explain cystic fibrosis

- CTFR gene mutation- transmembrane protein that transports ions across the surface of epithelial cells -Mucosal obstruction of exocrine glands

The small intestine is designed to maximize surface area. How does it do this?

- Circular folds (plicae circulares) -Villi: largest projections contain columnar epithelium -Absorptive enterocytes: facilitates transport of numerous small molecules into the enterocyte from the intestinal lumen -Microvilli

What are the three specific segments of the small intestine?

- Duodenum: 1st C shape part -Jejunum -Ileum

Where does the distal end of the ileum terminate? What is it and what does it do?

- Ileocecal valve -Sphincter that controls the entry of materials into the large intestine

Parietal cells (2)

- Intrinsic factor: secretes factor to small intestine to help absoprtion of B12 -Hydrochloric acid: helps with chemical digestion

What is special about the small intestine? What does it do?

- It is longest part of the alimentary canal -Finishes chemical digestion

What is inferior esophageal sphincter (cardiac sphincter)? What is it protected by? Strength? Function?

- Junction of the esophagus and the stomach -The diaphragm -Stronger, trying to protect from food coming back up

The mucous glands in the esophagus provide lubrication and assists food movement. What do the esophageal glands proper do? What do the esophageal cardiac glands do?

- Lubrication -Secretes mucin that protects from acidic contents in the stomach They secrete neutral mucin that protects the esophagus from acidic gastric juices.

Chief cells (2)

- Pepsinogen: proenzyme inactive once encounters acid becomes pepsin involved in protein digestion -gastric lipase: lipid digestion!

Intestinal crypts include what? (2)

- Stem cells: renew epithelium every 3-6 days -paneth cells: secrete antimicrobial peptides, counter against bad things we absorb

What is the superior esophageal sphincter? Is it thin or thick? Does it close or open when we inhale?

- The junction of the pharynx and the esophagus - Not thick -Closes as we inhale

What is in the division= hindgut

- Transverse colon (distal 1/3), descending & sigmoid colon, rectum

Where is the stomach? What is its maximum capacity? How long does the food remain in the stomach? Intraperitoneal or retroperitoneal?

- Upper left quadrant of abdomen (foregut) -4 liters=gallon -4 hours -Intraperitoneal

What produces bile? What stores bile?

- liver -gallbladder

Stem cells of the stomach

- surface mucous cells -mucous neck cells -parietal cells -enteroendocrine cell -chief cells

What is the esophagus? Is it restroperitoneal or intraperitoneal?

-A muscular tube that conducts ingested material from pharynx to stomach -Yes, the esophagus is retroperitoneal

Large intestine functions?

-Absorption of water -Compacts and solidifies undigestible wastes into feces -Stores the feces until defecation -Mass peristaltic movements

What does the digestive tract defend against?

-Chemical stresses (epithelium) -Mechanical stresses (epithelium) -Pathogens (lymphatic tissue (GALT) --> first line of defense)

Gallbladder

-Concentrates bile -Bile storage -Contracts to push bile to the small intestine

Stomach

-Contains cells that secrete substances to counter against acid -Begins chemical breakdown of proteins -Mixes and churns food to form chyme -Secretes intrinsic factor required for vitamin B12 absorption in small intestine -Absorbs some fat-soluble substances (for example, alcohol, aspirin)

What does the stomach do? - How does it do this?

-Continues digestion of the bolus (the term for food that has been chewed and swallowed) -Physical digestion: Churning -Chemical digestion: breakdown of proteins -Storage: Stays for 4 hours -Limited absorption: not absorption much in stomach -Produces chyme: food substance that leads to the stomach

What does the visceral peritoneum line? Is it in contact with organs?

-Covers surface of internal organs within the cavity -Yes

Large intestine

-Eliminate feces -Food residue is concentrated and temporarily stored prior to defecation -Primary site of water absorption -Propels feces toward rectum

Pancreas has both exocrine and endocrine functions What are they? What cells do they involve?

-Endocrine function: hormones of islet cells closely regulate blood glucose levels ------Pancreatic islets (islets of langerhans) ------Alpha cells: Secrete glucagon ------Beta cells: Secrete insulin -Exocrine function: produce and secrete digestive enzymes and bicarbonate, collectively called pancreatic juices, into the duodenum via the pancreatic duct

What is in the division = foregut

-Esophagus -Stomach -Gallbladder -Liver -Spleen -Duodenum (1st & 2nd parts)

When does the digestive system begin forming into its adult shape? When is the lumen open?

-In week 4 -by the 9th week

Included of the interior surface of the liver

-Inferior vena canva - Gall bladder

What are the three branches of the celiac trunk?

-Left gastric artery -Splenic artery -Common hepatic artery

What does the parietal peritoneum line? Is it in contact with organs?

-Lines internal walls, not in direct contact with organs -No, it is not in direct contact with organs

Lesser curvature Greater curvature

-Medial surface -Lateral surface

The esophagus has protection from :

-Microorganism invasion -Mechanical damage by unprocessed food -Chemical damage by acid of stomach

Small intestine

-Performs physical digestion via segmentation -Propels food at a rate slow enough for digestion and absorption -Primary site of nutrient absorption

Liver

-Produces bile -Produces clotting factors -Disposes of waste products -Disposes of worn-out cell components -Process the nutrients, toxins, and waste materials carried by the blood -Produces plasma proteins

What is interesting about liver donating?

-Remaining part of the donor liver and transplanted liver are large enough to maintain normal functions -liver can regenerate!!! back in months

Pancreas

-Secretes sodium bicarbonate serves to buffer the acidic gastric juice in chyme and inactivate pepsin from the stomach -Secretes enzymes that are active in digestion of sugar,s proteins and fats -Secretes hormones that regulate blood glucose levels

Regarding muscularis externa apart of the esophagus -Superior 1/3: What type muscle? Voluntary or Involuntary? -Middle 1/3: What type muscle? Voluntary or Involuntary? -Inferior 1/3: What type muscle? Voluntary or Involuntary?

-Skeletal muscle, voluntary -Mix of skeletal and smooth, both -Smooth muscle, involuntary

The exocrine part of the pancreas secretes enzyme-rich pancreatic juices through the pancreatic duct into the small intestine. What do they do?

-Sodium bicarbonate serves to buffer the acidic gastric juice in chyme, inactivate pepsin from the stomach, and create an optimal environment for the activity of pH-sensitive digestive enzymes in the small intestine. -Pancreatic enzymes are active in the digestion of sugars, proteins, and fats.

What type of epithelium is in the esophagus? How often is it replaced?

-Stratified squamous - 5-7 days

What is in the division = midgut

-duodenum (3rd & 4th parts) -jejunum -ileum -cecum -appendix -ascending colon transverse colon (proximal 2/3)

Small intestine: ileum What segment of the small intestine?

-last segment -

Small intestine: jejunum What portion of the small intestine What is it the primary region for

-middle portion - primary region for chemical digestion and nutrient absorption

esophogus

-secretes mucous in its superior portion to allow for smooth passage of the food through it -propels food to the stomach -contains cells that secrete substances to counter against acid

The stomach gets innervation from what?

-the celiac plexus (foregut) -greater splanchnic nerve -celiac ganglion

Cystic fibrosis- digestive tract

-thick glandular secretions through tract -reduced lipid absorption, particularly in the ileum up to 50% of dietary fat can be lost in feces without bile

Biliary apparatus steps

1) Left and right hepatic ducts merge to form a common hepatic duct 2)Common hepatic and cystic ducts merge to form a common bile duct 3) Main pancreatic duct merges with common bile duct at the hepatonpancreatic ampulla. 4)Bile and pancreatic juices enter duodenum at the duodenal papilla

What are the functions of bile?

1) digestion of lipids 2) transport cholesterol out of the body

A patient presents with pain in the center of their pelvic region, inferior to the umbilicus. In what region is their pain located? A)Hypogastric B)Epigastric C)Left lumbar D)Right inguinal E)Umbilical

A)Hypogastric

Mucous neck cells

Acidic fluid with mucin- lubricates stomach

Surface mucous cells

Alkaline fluid with mucin- helps protect stomach from itself

What supplies the stomach with blood?

All three branches of the celiac trunk supply the stomach with blood

Alpha cells produce? What stimulates its release?

Alpha cells produce glucagon, and low blood glucose levels stimulate its release.

Where is the gallbladder?

Attached to the inferior surface of the right lobe of the liver

All of the following are true regarding the gallbladder except: A)The cystic duct carries bile to the gallbladder for storage between meals containing large amounts of lipids. B)The gallbladder adds water to bile as it stores it, making it less concentrated. C)The gallbladder contracts to release bile when chyme containing a large amount of lipids enters the small intestines. D)The gallbladder is an intraperitoneal, muscular sac.

B)The gallbladder adds water to bile as it stores it, making it less concentrated.

Which organ receives the blood returning from the digestive tract (stomach, small and large intestine) carrying absorbed nutrients? A)The liver via the superior mesenteric vein B)The liver via the hepatic portal vein C)The heart via the inferior vena cava for distribution to the rest of the body D)The spleen via the splenic vein E)The spleen via the hepatic portal vein

B)The liver via the hepatic portal vein

Problems caused by reduced bile secretion may include ________. A)decreased protein digestion in the jejunum B)a reduced ability to digest lipids C)constipation D)appendicitis

B)a reduced ability to digest lipids

The ___________ sphincter regulates the passage of chyme into the small intestine. A)inferior esophageal B)pyloric C)internal anal D)cardiac E)gastrointestinal

B)pyloric

Which of the following are true regarding the pancreas: A)The secretory units of the exocrine pancreas are called hepatocytes B)The pancreatic duct delivers exocrine secretions from the pancreas to the small intestine. C)The pancreas is intraperitoneal. D)The pancreas has both exocrine and endocrine functions. E)The pancreas has a head near the C of the duodenum and a tail located closest to the spleen.

B, D, E

Beta cells produce? What stimulates its release?

Beta cells produce insulin, and elevated blood glucose levels stimulate the release of insulin.

Regarding the duodenum of the small intestine -What is its shape? -Where is it? -What are the four parts?

C-shaped Upper right quadrant of the abdomen -Superior 1st -Descending 2nd: foregut -Transverse 3rd: midgut -Ascending 4th

Which hepatic vessel supplies nutrients and other chemicals absorbed from the small intestine to the liver? A)common hepatic artery B)central vein C)hepatic artery proper D)hepatic portal vein E)celiac vein

D)hepatic portal vein

What is the fundus of the stomach?

Domed area superior to the junction between the stomach and esophagus

How often does the stomach replace?

Every 3-5 days

Enteroendocrine cell

Gastrin- released when food enters stomach, tells other cells to release their substances

Why do we need our epithelium for stomach?

Otherwise we could get gastric ulcers.

What does the duodenum do?

Receives substances from the pancreas and gall bladder that aid in digestion

What is the gallbladders function?

STORAGE!!!

Where does most nutrient absorption happen?

Small intestine

What is the peritoneal cavity?

Space between the peritoneal layers containing serosal fluid

What is the cardia of the stomach?

Superior, medial portion near the gastroesophageal junction

Digestive role of liver?

The digestive role of the liver is to produce bile and export it to the duodenum.

What is the esophageal hiatus?

The esophageal hiatus is the opening in the diaphragm through which the esophagus passes from the thoracic to abdominal cavity.

Digestive role of the gallbladder?

The gallbladder primarily stores, concentrates, and releases bile.

Explain what the gallbladder does

The gallbladder stores and concentrates bile, and releases it into the two-way cystic duct when it is needed by the small intestine.

Liver's main cell type plays a role in a wide variety of secretory, metabolic, and endocrine functions. What is the liver's main cell type?

The hepatocyte

Hepatic Portal System:

The liver receives blood from the normal systemic circulation via the hepatic artery. It also receives and processes blood from other organs, delivered via the veins of the hepatic portal system. All blood exits the liver via the hepatic vein, which delivers the blood to the inferior vena cava.

Digestive role of the pancreas?

The pancreas produces pancreatic juice, which contains digestive enzymes and bicarbonate ions, and delivers it to the duodenum.

What does the esophagus get its innervation from?

The parasympathetic division going to the esophageal plexus that carry fibers from the vagus nerve

The pancreas also contains endocrine cells called the islets of Langerhans. What do they do?

These vital cells produce the hormones including insulin and glucagon, involved in regulating blood sugar

What are duodenal papilla:

Where bile and pancreatic secretions enter the duodenum between the 2nd and 3rd parts of the duodenum

What is the Z-line?

Where esophageal epithelia changes to gastric epithelia

What is bile?

a mixture secreted by the liver to break down large lipid globules into smaller lipid globules in the small intestine

This muscular sac stores, concentrates, and, when stimulated, propels the _______ into the duodenum via the ______ ______ ______.

bile, common bile duct

What is the order of processing in the liver?

capillaries-->hymphatic vein--> liver--> capillary bed--> processed

Common hepatic duct:

carries bile away from the liver towards the small intestines.

Hepatic artery proper:

delivers oxygenated blood from the heart to the liver. It is a branch of the common hepatic artery, which is a branch of the celiac trunk.

Hepatic portal vein:

delivers partially deoxygenated blood containing nutrients and toxins absorbed from the small intestine.

The liver is divided into how many lobes?

four lobes: -a large right lobe, -a smaller left lobe, - a small inferior quadrate lobe, -a small posterior caudate lobe.

The small intestine has what cells that lubricate the surface and protect it?

goblet cells

What is the porta hepatis?

it is where the hepatic artery proper, hepatic portal vein, and common hepatic duct enter the liver.

What is the body of the stomach?

largest region: the area between the fundus and the plyorus

What is the plyoric part of the stomach?

near the junction of the stomach and duodenum

Cystic fibrosis- liver

obstruction of bile canaliculi causes liver damage and sometimes cirrhosis

in regards to cystic fibrosis, anywhere we secrete things it can cause ________

problems

The digestive system starts as a simple _______ tube, undergoes _______ and ________ to result in the adult anatomy

straight, folding, rotation

Circular folds, villi, and microvilli in the small intestine greatly increases the ______ _______for absorption of nutrients.

surface area

Chemical digestion in the small intestine relies on the activities of what three accessory digestive organs:

the liver, pancreas, and gallbladder.

Cystic fibrosis - pancreas

thick secretions cause impaction of the pancreatic ducts ------causes chronic fibrosis and fatty replacement ------altered secretions have a lower pH--> damages pancreatic epithelium ------maldigestion and malabsorption mainly with dietary lipids and fat-soluble vitamins (pancreatic lipase)

Where is the liver? What is special about the liver? What are the four incompletely separated lobes?

upper right quadrant Largest gland in the body -Right lobe -Left lobe -Caudate lobe -Quadrate lobe

What is porta hepatis?

where vessels, bile ducts, and nerves enter/exit the liver

Does the digestive system develop after birth?

yes