Name: ______Date: ______

Digestive System Notes

Digestion:

  • Digestion breaks food molecules down into smaller molecules
  • It is necessary to make smaller molecules because these nutrients need to be used by CELLS.
  • Only small molecules can pass through the cell membrane and into the cell so it can be used.
  • EX: We break starch ( a large molecules) down into glucose (a small molecule that can cross cell membranes) so our cells can do respiration and make energy!
  • What are each of the following broken down into???
  • Proteins 
  • Starch 
  • Lipids 
  • Carbohydrates 
  • Steps of Digestion:
  • Ingestion  Digestions  Absorption  Excretion

Types of Digestion:

  • Mechanical – physically breaking food down into smaller pieces
  • This creates more surface area, so enzymes can get to more molecules
  • Chemical – use of chemicals and enzymes to break food into substances that can be absorbed

Mouth:

  • Teeth are used for mechanical digestion to break the food into smaller pieces, so it can be easilyswallowed.
  • Saliva contains an enzyme (amylase) used in chemical digestion, which breaks down starches into simple sugars
  • The tongue is your strongest muscle used to manipulate food during mastication

Esophagus:

  • The tube the food travels down to get to the stomach
  • Peristalsis is the motion that pushes the food down the tube. The tube pinches off above the food pushing it toward the stomach
  • You have an epiglottis that covers your esophagus while you are breathing and covers your trachea while you are swallowing
  • This prevents food from “going down the wrong tube”

Stomach:

  • The stomach performsmechanical and chemical digestion of food.
  • The stomach secretes a powerful acid (pepsin) that breaks food down
  • It also churns mixing the food with the acid and breaking it down mechanically
  • Chyme is the mixture of stomach acid (pepsin), broken down food, and saliva that flows from the stomach into the small intestine

Duodenum:

  • This is the first section of the small intestine, where most of the chemical digestion of carbohydrates, lipids, and proteins occurs
  • Chyme is joined with enzymes from the liver and pancreas that reduce acidity of the chyme and chemically digest the food

Small Intestine:

  • The small intestine are covered in little finger like projections called villi
  • Villi increase the surface area of the small intestine to increase absorption of nutrients
  • The usable nutrients are removed from the chyme and travel across the villi into the blood vessels that are inside it

Large Intestine:

  • When the food arrives in the large intestine it is nutrient free
  • The large intestine pulls any excess water out of the remaining indigestible material creating feces
  • The large intestine is filled with bacteria that help our digestion process
  • When the large intestine is not removing enough water, diarrhea will result
  • When the large intestine removes too much water, constipation will occur

Rectum:

  • The rectum will store the feces until there is enough to pass out of the body
  • When the rectum is full, you feel the urge to go to the bathroom
  • There is a sphincter muscle at the bottom of the rectum called the anus
  • This squeezes shut to keep feces in the rectum and expands to allow it out when passing a stool

Liver, Pancreas, and Gallbladder:

  • The liver and pancreas secrete enzymes and digestive fluids that mix with the chyme in the duodenum
  • The pancreas secretes a fluid to neutralize the acidity of the stomach acid
  • The liver secretes bile, which is used to break down fatty acids (lipids)
  • Bile is stored in the gall bladder

Digestive Diseases:

  • Diarrhea – too much fluid in the bowel movements
  • Caused by the large intestine not removing enough water; Can be caused by viruses or bacteria
  • Can lead to dehydration and eventually death
  • Constipation – too much water being removed from the bowel movements
  • Can be caused by poor diet or not taking in enough water
  • Symptoms can be alleviated by taking laxatives
  • Appendicitis - an infection of the appendix, usually remedied by removing the appendix
  • GERD - heartburn; caused by stomach acid rising into the esophagus and burning the lining
  • IBS - Irratable Bowel Syndrome; certain foods affect the lining of the intestines causing diarrhea
  • Ulcers - when the stomach acid burns the stomach creating sores on the inside the stomach wall, can cause blood to move throught the digestive system creating blackish bowel movements
  • Cirrhosis - when the liver cells start to die because they have been abused by poor diet or alcohol abuse; can be cured by getting a liver transplant
  • Diverticulitis - small bulging sores anywhere in your intestinal tract; can be caused by certain food becoming lodged in the bowels
  • Ulcerative Colitis - when the immune system attacks the bowels causing constant diarrhea
  • Hemorrhoids - when a vein or artery in the anus protrude or swell; this can be caused by constipation or straining during deffication
  • Celiac’s - an allergy to gluten (found in many grains), causes rashes and diarrhea
  • Lactose Intolerance - means your digestive system is not able to digest the lactose sugar found in milk

Name: ______Date: ______

Digestive System Notes

Digestion:

  • Digestion breaks food molecules down into ______molecules
  • It is necessary to make smaller molecules because these nutrients need to be used by ______.
  • Only ______molecules can pass through the cell ______and into the cell so it can be used.
  • EX: We break ______(a large molecules) down into ______(a small molecule that can cross cell membranes) so our cells can do ______and make energy!
  • What are each of the following broken down into???
  • Proteins  ______
  • Starch  ______
  • Lipids  ______
  • Carbohydrates  ______
  • Steps of Digestion:
  • ______ Digestion______ Excretion

Types of Digestion:

  • Mechanical – ______breaking food down into smaller pieces
  • This creates more ______, so enzymes can get to more molecules
  • Chemical – use of chemicals and ______to break food into substances that can be ______

Mouth:

  • ______are used for ______digestion to break the food into smaller pieces, so it can be easily ______
  • Saliva contains an ______(amylase) used in chemical digestion, which breaks down ______into ______
  • The tongue is your strongest muscle used to manipulate food during mastication

Esophagus:

  • The ______the food travels down to get to the ______
  • Peristalsis is the ______that pushes the food down the tube. The tube ______off above the food pushing it toward the stomach
  • You have an ______that covers your esophagus while you are ______and covers your trachea while you are ______
  • This ______food from “going down the wrong tube”

Stomach:

  • The stomach performs ______and ______digestion of food.
  • The stomach secretes a powerful ______(pepsin) that breaks food down
  • It also ______mixing the food with the ______and breaking it down ______
  • ______is the mixture of stomach acid (______), broken down ______, and ______that flows from the stomach into the ______

Duodenum:

  • This is the first section of the ______intestine, where most of the ______digestion of carbohydrates, ______, and proteins occurs
  • Chyme is joined with ______from the ______and ______that reduce ______of the chyme and chemically ______the food

Small Intestine:

  • The ______intestine are covered in little finger like projections called ______
  • Villi increase the ______of the small intestine to increase absorption of nutrients
  • The usable ______are removed from the ______and travel across the ______into the ______that are inside it

Large Intestine:

  • When the ______arrives in the large intestine it is ______
  • The large intestine pulls any excess ______out of the remaining indigestible material creating ______
  • The large intestine is filled with ______that help our digestion process
  • When the large intestine is ______removing enough water, ______will result
  • When the large intestine removes ______water, ______will occur

Rectum:

  • The rectum will ______the feces until there is enough to pass out of the body
  • When the rectum is ______, you feel the ______to go to the bathroom
  • There is a ______muscle at the bottom of the rectum called the ______
  • This ______shut to keep feces in the ______and expands to allow it out when passing a ______

Liver, Pancreas, and Gallbladder:

  • The liver and pancreas secrete ______and digestive fluids that mix with the ______in the ______
  • The pancreas secretes a fluid to ______the acidity of the stomach acid
  • The liver secretes ______, which is used to break down ______(lipids)
  • Bile is stored in the ______

Appendix:

  • Is located near the junction of the ______and ______
  • The appendix is a ______organ, which means it was once used but ______in size as it became less ______
  • Some organisms use the appendix to help break down ______in very fibrous substances (______)

Digestive Diseases:

  • Diarrhea – too much ______in the bowel ______
  • Caused by the ______intestine ______removing enough water
  • Can be caused by ______, bacteria, etc.
  • Can lead to ______and eventually death
  • Constipation – too much water being ______from the bowel movements
  • Can be caused by poor ______or not taking in enough ______
  • Symptoms can be alleviated by taking ______
  • Appendicitis - an infection of the appendix, usually remedied by removing the appendix
  • GERD - heartburn; caused by stomach acid rising into the esophagus and burning the lining
  • IBS - Irratable Bowel Syndrome; certain foods affect the lining of the intestines causing diarrhea
  • Ulcers - when the stomach acid burns the stomach creating sores on the inside the stomach wall, can cause blood to move throught the digestive system creating blackish bowel movements
  • Cirrhosis - when the liver cells start to die because they have been abused by poor diet or alcohol abuse; can be cured by getting a liver transplant
  • Diverticulitis - small bulging sores anywhere in your intestinal tract; can be caused by certain food becoming lodged in the bowels
  • Ulcerative Colitis - when the immune system attacks the bowels causing constant diarrhea
  • Hemorrhoids - when a vein or artery in the anus protrude or swell; this can be caused by constipation or straining during deffication
  • Celiac’s - an allergy to gluten (found in many grains), causes rashes and diarrhea
  • Lactose Intolerance - means your digestive system is not able to digest the lactose sugar found in milk