Digestive System and Metabolism 3.2.2 & 3.2.5
Esophagus function and enzymes
Function: - conduct for food and liquids that have been swallowed into the pharynx to reach the stomach Enzymes: none
Whats a bolus?
Small rounded mass of a substance. Chewed food at the moment of swallowing is an example of a bolus.
What enzymes act inside the small intestine & what are the functions of these enzymes?
- Amylase: acts on starch and breaks it down into small carbohydrate molecules - Protease: acts on proteins and breaks them down into amino acids - Lipase: breaks down dietary fats into smaller molecules called fatty acids & glycerol
What are the 3 sections of the large intestine & what roles does each play in digestion or absorption?
- Cecum: takes digested liquid from the ileum and passes it on to the colon - Colon: principal place for water reabsorption and absorbs salts when needed - Rectum: where leftover waste sits until it is ready to be emptied through the anus
Explain what happens in the large intestine to cause diarrhea or constipation. How does the function of the large intestine relate to another key resource?
- Constipation: colon absorbs too much water or if the colons muscle contractions are slow/sluggish, causing the stool to move through the colon too slowly. As a result, stools can become hard and dry. - Diarrhea: the opposite of constipation. Theres not enough water being absorbed from the waste matter & the stool is liquid as a result. - Key resource = water
What are the 3 sections of the small intestine and what role does each section play in digestion or absorption?
- Duodenum: receives parts digested food, acid, and bile - Jejunum & Ileum: break down food fully
Describe the main function of the human digestive system
- Ingestion of food - Secretion of fluids and digestive enzymes - Mixing & movement of food & wastes through the body - Digestion of food into smaller pieces - Absorption of nutrients - Excretion of wastes
What mechanical and chemical digestion occur in the stomach?
- Mechanical: segmentation. Its the back and forth mixing in the stomach that aides in mixing food and digestive enzymes to form chyme - Chemical: Hcl and pepsin forms chyme
What are the different functions of the pancreas & how is the pancreas directly related to digestion?
- Pancreas has an endocrine function (releases juice directly in bloodstream) and an exocrine function (releases juices straight into ducts) - Enzymes that are secreted by the Pancreas are sent to the small intestine for further break down of food
What cells in the stomach function to form enzymes and acids?
- Parietal cells in the stomach function to form enzymes and acids - The protein digesting enzyme pepsin is activated by exposure to hydrochloric acid inside the stomach. Chief cells, also found within the gastric pits of the stomach produce 2 digestive enzymes: pepsinogen and gastric lipase. Pepsinogen is the precursor molecule of the very potent protein - digesting enzyme pepsin.
Using what you know about the chemical makeup or stomach contents & the control of food moving through the GI tract, provide a reason some people get heartburn. What is actually happening to cause this burning sensation in the chest?
- People can get heartburn due to GERD (Gastroesophageal reflux disease) Its caused by acid refluxing back into the esophagus. This causes pain such as the burning sensation. - The stomach combines food, acids, and enzymes together to begin digestion. There are special protective cells that line the stomach to prevent the acid from causing inflammation. The esophagus does not have this same protection, and if stomach acid and digestive juices reflux back into the esophagus, they can cause inflammation and damage to its unprotected lining.
What enzymes are produced by the pancreas and what are their functions?
- Proteases: help digest proteins - Amylase: helps digest sugars (carbohydrates) - Lipase: helps digest fat
For lunch, you have a turkey sandwich on wheat bread with mayonnaise & lettuce. Describe how each component of this meal would be broken down in the digestive system.
- The lettuce would be broken down in the mouth along with the others, where then the food would be transported to the stomach to begin digestion. The bread would be moved to the small intestine to be fully digested. The turkey would be moved to the pancreas to be digested along with the mayonnaise.
Digestive System Overview
- Works like an assembly line in reverse - Carbs, fats, proteins are broken down into smaller molecules that can be used by the body - Extracts nutrients and gets rid of unnecessary wastes
What are other functions of the liver in the body?
- secretes hormones and chemicals due to it producing bile - detoxifies blood from harmful substances - stores simple sugar glucose - breaks down hemoglobin - destroys old red blood cells - converts stored sugar into usable sugar when the body glucose level falls below normal
Oral cavity, pharynx, (+accessory organs: salivary glands, tongue, teeth)
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Esophagus and stomach
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Small intestine and large intestine
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Pancreas, liver, & gallbladder
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Milk digestive process
1) Mouth: slightly acidic salvia combines with milk and breaks it down. Enzymes: Salivary amylase-- carb digestion. Lysozyme-- Protein digestion 2) Swallow and then travels down the 3) esophagus and into the 4) stomach: gastric juices break down the milk further and kill bacteria Enzymes: pepsin-- protein digestion sends milk into the 5) small intestine: nutrients like amino acids and fatty acids are absorbed enzyme: lactase-- breaks lactose into glucose Materials not absorbed for energy or nutrition are pushed to the 6) large intestine and processed as 7) fecal matter and pushed into the 8) rectum. waste fluids fill the 9) bladder
How does food move through the intestines?
1) duodenum 2) jejunum 3) ileum 4) cecum 5) colon 6) rectum
What mechanisms are in place to make sure food doesn't "go down the wrong tube" and into the windpipe?
A flap of skin, known as the epiglottis, separates the esophagus from the trachea, thus preventing food from "going down the wrong tube"
What is the function of the tongue?
Aids in moving food in the mouth, chewing, and swallowing
What is chyme and how does the stomach mix this material?
Chyme is a thick semifluid mass of partially digested food and digestive secretions that is formed in the stomach and intestine during digestion - In the stomach, digestive juices are formed by the gastric glands' these secretions include the enzyme pepsin, which breaks down proteins and hydrochloric acid
Where do bile and pancreatic enzymes enter the small intestine?
Duodenum
Chemical digestion
Enzymes break fats, carbs, and proteins into their building blocks so they can be used by the body. Once they are broken down, they become raw material for the production of the body's energy currency, ATP.
large intestine function & enzymes
Function: - absorbs water from the remaining indigestible food matter and transmit the useless waste material from the body Enzymes: none
Liver functions & enzymes
Function: - bile production and excretion - excretion of bilirubin, cholesterol, hormones, + drugs - metabolism of fats, proteins, and carbs - enzyme activation - storage of glycogen, vitamins, and minerals - synthesis of plasma proteins, such as albumin and clotting factors Enzymes: - ALT - breaks down food into energy - AST - helps with injured cells
Pancreas function and enzymes
Function: - converts the food we eat into fuel for the bodys cells - exocrine function that helps w digestion - endocrine function that regulates blood sugar Enzymes: - proteases - breaks down proteins - lipase - works w bile from liver to break down fat molecules - amylase - breaks down carbs into sugars transfers into the small intestine
Pharynx functions & enzymes
Function: - helps with swallowing - serves as a pathway for the movement o food from the mouth to the esophagus Enzymes: none
Stomach function & enzymes
Function: - holds food - mixes and grinds food - secretes acids and enzymes that break down food further to turn into a liquid / paste Enzymes: - Pepsin - breaks down protein - Gastric lipase - breaks down butter fat - Lipase - breaks down fats
Salivary glands function & enzymes
Function: - produce saliva - keeps mouth and digestive system moist - breaks down arbs - lubricates passage of food down from the pharynx to the esophagus to the stomach Enzymes: - lingual lipase - starts digestion of lipids/fats - salivary amylase - carbs digestion - lysozyme - protein digestion
Gallbladder function & enzymes
Function: - stores and concentrates bile (enzyme produced by the liver) Enzymes: - bile - breaks down large masses of fat
Mouth functions and enzymes
Function: - start of the digestive system - breaks down food chemically and mechanically Enzymes: - none
Small intestine function & enzymes
Functions: - absorption of nutrients and minerals from food Enzymes: - lactase - breaks lactose into glucose - sucrase - hydrolysis of sucrose to fructose and glucose - maltase & lactase - break disaccharides into single sugars (monosaccharides) like glucose
The digestive system consists of what tube?
Gastrointestinal (GI) tract
Why doesn't gastric juice digest the inside of the stomach?
In our stomach, mucus forms a layer between the deadly gastric juices and the lining of the stomach walls. This mucus lining prevents the acid present in the gastric juices from damaging the stomach.
What is the function of the large intestine in relation to digestion?
In relation to digestion, the large intestine absorbs water and salts. it also stores waste material until they're thrown out of the body.
How is insulin related to the digestive system?
Its a natural hormone produced in the pancreas. When you eat, your pancreas releases insulin to help your body make energy out of sugars (glucose). It also helps you store energy. Insulin is a vital part of metabolism. Without it, your body would cease to function
What is the oral cavity and what does it contain?
Its the first part of the digestive tract & it contains the mouth along with the organs in the mouth. This includes the lips, inside lining of the lips & cheeks, teeth, gums, front ⅔ of the tongue, door of mouth below tongue, and roof of mouth.
What is the size of the liver and where is it located?
Liver is located in the upper right portion in the abdominal cavity. It weighs about 3 pounds
How does liver function in relation to digestion?
Livers main function with the digestive system is to process the nutrients absorbed from the small intestine
Does any digestion of food occur in the esophagus?
No, the esophagus is the organ into which the swallowed food is pushed
What are the size and location of the pancreas?
Pancreas is about 6 in long and located in the abdomen
How does the pancreas connect to the rest of the digestive system?
Pancreas lies beneath the stomach. Connects the rest of the digestive system through the small intestine & the duodenum
What is peristaltic movement and how does it function in the esophagus?
Peristalsis consists of waves of muscular contractions that move a bolus, or small oval mass of digestive contents, along the length of the digestive tract. - During a peristaltic movement, the circular muscles contract behind the bolus while circular muscles ahead of the bolus relax. - Longitudinal muscles ahead of the bolus then contract, shortening adjacent segments. - A wave of contraction in the circular muscles then forces the bolus forward
Mechanical digestion
Physically mashing or tearing the bites of food we put in our mouths
What is the function of salivary glands?
Produces saliva, which keeps the mouth and other parts of the digestive system moist
Rectum & anus function and enzymes
Rectum: Function: - last part of digestive tract - last straight section of the large intestine before reaching the anus ************************************* - anus is the opening at the lower end of the digestive tract that controls the expulsion of feces Enzymes: none
What does the GI tract do?
Serves as the direct pathway for what you eat and excrete. Various accessory organs help with the mechanical breakdown and the chemical digestion of food.
What are sphincters and how are they related to the stomach?
Sphincters are circumferential muscles that can relax or constrict to regulate the passage of material through a particular area. The stomach is bound by 2 sphincters in humans: the lower esophageal sphincter that keeps stomach acid in the stomach and the pyloric sphincter that regulates the flow of food in the stomach into the duodenum.
How does the large intestine help maintain a water balance in the body?
The large intestine helps the body digest and remove water from the remains of food (feces) after which it will go through the rectum
What is the pH within the small intestine and how is this pH maintained?
The pH of the small intestine is 6 This is maintained through bicarbonate ions.
Where are the soft and hard palate located and what are their functions?
The soft and hard palette are located at the roof of the mouth. The hard palate is at the front, and the soft is at the back. The hard palate holds the root of the teeth. The soft palate presses down for swallowing
What role does the stomach play in decontaminating the incoming food matter?
The stomach releases enzymes that kill bacteria in food and balance pH
Provide an example that illustrates how the structure of an organ in the digestive system is specifically linked to its function.
The structure of the stomach is a hollow organ, or "container". It holds food while its being mixed with enzymes that continue the process of breaking down food into a usable form.
What does the digestive system do?
Turns food into substances the body can use for energy and growth and repair
What are the primary functions of the stomach?
breaks down and digests food in order to extract necessary nutrients from what you have eaten
Catabolism
energy rich fuel molecules are broken down to release their energy to supply the cells needs
What is the relationship between the liver and the gallbladder?
liver creates bile and sends it to the gallbladder which stores, concentrates, and secretes bile. They are dependent upon each other.
What is the function of bile and where does it enter the digestive tract?
produced by the liver, held in the gallbladder until needed for digestive fatty foods in the duodenum of the small intestine
Anabolism
tasks simple building blocks and uses them to build up more complex molecule a cell ma need for growth and repair
