Chapter 14: Digestive System

What does bile do?

-It acts like a detergent to emulsify, or mechanically break down, large fat globules into thousands of tiny ones, providing a much greater surface area for the pancreatic lipases to work on. -Necessary for absorption of fats and fat-soluable vitamins

What is the relative size of the duodenum, compared to the rest of the small intestine?

-It is 20 to 25 cm long (widest/shortest and is c-shaped or horseshoe-shaped structure) -Function: Responsible for the continuous breakdown process. (Where the food mixes with bile from the gallbladder and digestive juices from the pancreas)

What is Gluconeogenesis?

-"formation of new sugar" -Liver makes glucose from noncarb substances such as fats and proteins

What is the 3rd major part of the digestive system and examples:

-Accessory organs -Help to produce digestive juices and help to break down food -Mouth, teeth, salivary glands, tongue, liver, gallbladder, pancreas, and appendix (any organ that does not have the same structural organization as the alimentary)

What is an example of an enzyme in Saliva and its job?

-Amylase breaks down starches into sugars, which your body can more easily absorb.

Describe the digestion that occurs in the large intestine?

-Chemical digestion (do not secrete enzymes) 1. Chyme passes from the ileum of the small intestine through to the large intestine. 2. Bacteria secrete vitamins, which are absorbed. (ascending colon) 3. Contractions move chyme through intestines (transverse colon) 4. Water is absorbed and stool is formed (descending colon) 5. Waste eliminated as feces through the sigmoid, rectum, and anus

What is the make up of feces?

-Contains undigestible food, 1000 kinds of bacteria, and small amounts of water and mucous.

Describe chyme

-Food that has been processed in the stomach and in which resembles heavy cream. -Enters small intestine through the pyloric sphincter.

Distinguish between the location of the hard and soft palate of the mouth.

-Hard palate= anterior roof of the mouth -Soft palate= Posterior roof of the mouth

Constipation

Hard, slow stools that are difficult to eliminate; often a result of too little fiber in the diet

How is the Peristalsis different in the large vs small intestine?

Peristaltic waves in small intestine are smaller and more regular, pushing the chyme for 3-6hrs before passing it to the large intestine where any final absorption takes place.

List the 2 main groups of the digestive system:

The alimentary canal, and the accessory digestive organs

What is absorbed by the large intestine?

Vitamin K & B's, ions, and most of the remaining water.

Describe the brush border?

-The site of terminal carbohydrate digestions -Thousands of tightly packed microvilli -A complex and highly plastic organelle required for intestinal homeostasis and is specialized for absorption of nutrients

What happens to your stomach after the food enters?

-The stomach muscles mix the food and liquid with digestive juices. The stomach then slowly empties its contents, called chyme, into your small intestine. -Gastrin is produced

How big is the small intestine?

2-4 meters (6-13ft)

What is the main job of the jejunum and ileum?

Absorption

What is the end product of stomach digestion?

Chyme

Where is the small intestine in relation to the large intestine?

Inside of it/ surrounded by the large intestine

What is the function of the stomach?

It acts as a temporary "storage tank" for food and is a site for food breakdown.

What is the hepatic portal circulation?

It brings nutrient-rich blood draining from the digestive viscera directly to the liver.

Identify the 3 ways the small intestine increases surface area for maximum absorption?

Microvilli, villi, and circular folds

Hemorrhoids

Swollen, painful rectal veins; often a result of constipation

What openings in the pharynx are closed during deglutition?

The esophageal sphincter

What part of the GI tract comes directly after the mouth?

The pharynx (oropharynx and laryngopharynx)

What is the 1st major part of the digestive system?

The upper alimentary canal (mouth thru stomach) -Anterior to the diaphragm

How many colons are there?

There are four different colons

Rectal Polyps

These soft structures are rather common and occur in varying sizes and numbers. There are two types: pedunculated (on a stalk) and sessile (on the mucosal surface).

What is the role of the Rugae inside the stomach?

They are folds inside the stomach that increase surface area.

What is the job of gastric pits?

They lead into gastric glands that secrete gastric juice solution.

How does food enter the large intestine?

Through the ileocecal valve

List the lower accessory organs:

liver, gallbladder, and pancreas

Ulcer

open sore or lesion of the skin or mucous membrane accompanied by sloughing of inflamed necrotic tissue

What is the function of the appendix?

-Protects good bacteria in the gut -Do not use anymore

What are the 4 main jobs of pancreatic juices?

1. Complete digestion of starch (amylase) 2. Carry our about half of protein digestion (tryspin) 3. Responsible for fat digestion (lipases) 4. Digest nucleic acids (nucleases)

List the 4 basic tissue types that make up the GI tract from the esophagus thru the large intestine.

1. Mucosa-innermost layer 2. Submucosa- Beneath mucosa 3. Muscularis externa- Muscle layer 4. Serosa- Outermost layer

What is the order of the food movement through the GI tract/Alimentary canal?

Mouth, esophagus, stomach, small intestine, large intestine, rectum and then the anus.

What is the role of the pancreas?

Produces insulin and glucagon which are used in the liver.

Cirrhosis

chronic degenerative disease of the liver

Crohn's disease

chronic inflammation of the intestinal tract

How many lobes are there to the liver?

four

Diarrhea

frequent passage of loose, watery stools

What are the 4 types of permanent teeth.

incisors, canines, premolars, molars

pancreatitis

inflammation of the pancreas that occurs when pancreatic enzymes that digest food are activated in the pancreas instead of the duodenum and attack pancreatic tissue, causing damage to the gland

What 2 hormones does the pancreas produce?

insulin and glucagon

Where does most digestion occur?

pyloric region

Indigestion

symptoms resulting from difficulty in digesting food

How would you describe food movement through the jejunum and Ileum?

-Jejunum absorbs most of your nutrients: carbs, fat, minerals, proteins, and vitamins. Nutrients vigorously move throughout this area. -Ileum absorbs the end products of digestion and release hormones that regulate feelings of fullness.

What is the 2nd major part of the digestive system and examples:

-Lower Alimentary Canal -Small and large intestine thru anus -Posterior to the diaphragm

What is the difference between mastication and deglutition?

-Mastication: Chewing or physical breakdown of food. -Deglutition: Swallowing of food made easier by tongue

What are the 2 tonsils called at the posterior of the mouth and what can happen when they become inflamed?

-Palatine and lingual tonsils -If inflamed, they will partially block the entrance into the throat (pharynx), making swallowing difficult and painful.

Chemical breakdown

-Saliva contains enzymes that break down food -Ex: Amylase, which breaks down starches into sugars so that your body can more easily absorb it

How long does it take for the stomach to empty? How much leaves the stomach at a time?

-Takes about 4 hrs -3 ml leaves the stomach at a time

Describe the size comparison of the small to the large intestine.

-The large intestine is larger in diameter but shorter in length -Large intestine= 1.5 meters

What is the difference between glycogenesis and glycogenolysis?

-glycogenesis: Glycogen formation -glycogenolysis: Breaks down stored glycogen into individual glucose molecules.

intestinal gas

-occurs bc of swallowing more air than usual, overeating, smoking, or chewing gum. -can damage the lining of the intestines, making it difficult for the body to absorb nutrients

Describe the 4 parts of the stomach and put them in order of food travel from start to finish:

1. Cardiac region- surrounds cardioesophageal sphincter, through which food enters the stomach from the esophagus. 2. Fundus- Expanded part of stomach and lateral to the cardiac region. 3. Body- Midportion 4. Pylorus- Terminal part of stomach

What are the 3 parts of the small intestine in order of food movement, include their functions?

1. Duodenum: Smallest and connected to pyloric sphincter (where juices from liver and pancreas enter) 2. Jejunum- Feet of material and absorbs sugars, amino acids, and fatty acids. 3. Ileum- connected to large intestine and absorbs any final nutrients.

What are the 5 major roles of the digestive system?

1. Ingestion- Taking in food 2. Digestion- Physical and chemical breakdown of food 3. Propulsion- Movement of food (peristalsis) 4. Absorption- Movement of nutrients into the bloodstream 5. Defecation- Removal of waste (Feces)

Chemical Breakdown of food:

1. Rugae 2. Gastric Pits- Depressions in the rugae that contain cells that produce digestive enzymes. 3. Gastrin- Hormone produced in stomach when bolus enters. -Causes: 1. Parietal Cells: Produce HCI=acidic environment that allows other juices to do their job. 2. Chief Cells: Produce pepsinogen to break down proteins. 3. Mucosal Cells: Protects stomach from acid erosion.

How much food can your stomach hold?

4 liters (1 gallon) of food

Why does someone get diarrhea?

Bc a condition has rushed food residue through the large intestine before that organ has had sufficient time to absorb the water.

Why does someone get constipated?

Bc food residue remains in the large intestine for too long and absorbs too much water causing the stool to turn very hard and difficult to pass.

Why is the Liver considered the most important metabolic organ in the body?

Because it breaks down food and makes food/nutrients into a usable form of energy for our bodies. (all nutrients travel to the liver) -Bodies chemistry lab and produces bile which emulsifies fat so it can be absorbed

Why is food in the GI tract technically considered "outside the body"?

Because it has contact only with cells lining the tract and is open to the external environment at both ends.

Why doesn't the large intestine have villi like the small intestine?

Because most nutrient absorption has occurred before it reaches the large intestine. -Produces goblet cells in its mucosa instead which produce mucus

Describe where the esophagus is situated compared to the vertebral column and the trachea.

Between the trachea and the vertebral column and starts in the larynx through the diaphragm to the stomach.

What are the 3 digestive molecules released by the small intestine that aid in digestion?

Brush border enzymes, and secretin and CCK hormones.

List the parts of the large intestine in the correct order of waste movement:

Cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, and anal canal.

Describe Bolus

Food that has been broken down in the mouth (physically and chemically) is swallowed.

What is another name of the alimentary canal?

Gastrointestinal tract (GI)

How is the duodenum situated to the pancreas?

It curves around the head of the pancreas, and is about 25cm long.

Describe the location of the stomach in the abdomen:

It is on the left side of the abdominal cavity and hidden by the liver and diaphragm.

What is the role of the epiglottis during deglutition?

It shuts the windpipe so that the Bolus goes one way.

What is the function of the gull bladder?

It stores bile

How long are the jejunum and the ileum together?

Jejunum= 2.5 meters (8ft) Ileum= 3 meters (12 ft)

What is absorbed in the stomach?

No absorption takes place in the stomach (happens after the chyme is released to small intestine)

What is the role of peristalsis in the esophagus and in the stomach.

One peristaltic wave moves bolus down the esophagus and into the stomach. (Mixes food w/ enzymes)

If the large intestine doesn't have any digestive enzymes, what is metabolizing the remaining nutrients?

Resident bacteria live w/in its lumen metabolize some of the remaining nutrients, releasing gases (methane and hydrogen sulfide) that contribute to the odor of feces.

List 4 accessory Digestive organs:

Salivary glands, teeth, pancreas, liver, and gallbladder

Gallstones

Small crystals that form from bile in the gallbladder.

Where does the bolus enter the stomach?

The cardiac sphincter

What are the major roles of the mouth during digestion?

The digestive system starts when you chew. Your salivary glands make saliva to moisten the food so it moves easily through your esophagus into your stomach. (Mechanical and Chemical digestion)

What valve does the digested product of the small intestine leave through to enter the large intestine?

The ileocecal valve

What is the longest part of the small intestine?

The ileum (about 3.6 meters and is the terminal end)

Where do most of the enzymes come from for final digestion of food?

The internal cells, pancreas, and the liver

What is the job of the goblet cells?

They produce mucus that acts as a lubricant to ease the passage of feces to the end of the digestive tract.

What is left at the end of the ileum?

Water, indigestible food materials, and large amounts of bacteria

What is absorbed by the body in the large intestine?

Water, salts, and vitamins

How does someone get appendicitis?

When too much bacteria accumulates and multiplies and causes inflammation of the appendix.

irritable bowel syndrome

a common condition of unknown cause with symptoms that can include intermittent cramping, abdominal pain, bloating, constipation, and/or diarrhea

diabetis

a metabolic disease resulting in high blood sugar due to lack of insulin or cells not responding to produce insulin glucose rise to dangerouse levels

Heartburn

a painful burning sensation in the chest caused by gastroesophageal reflux (backflow from the stomach irritating the esophagus)