Ms.  Isenor     Name:_____________________________    

    Biology  12  Digestion  Workbook  

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DIGESTION  -­‐WORKBOOK    

1. What is digestion? The physical and chemical breaking down of food into molecules small enough to move through intestinal cells.

2. What is the difference between digestion and absorption? Digestion is the breaking down of large molecules into smaller ones. Absorption occurs after digestion, and involves these small molecules moving across cell membranes and into the blood stream or lymph.

3. Compare the composition of the food we eat with the molecules that our cells actually use.

Food is a mixture of large macromolecules of proteins, fats, nucleic acids, and polysaccharides. Our cells actually only use the small molecules which make up these macromolecules (amino acids, glucose, nucleic acids, glycerol, fatty acids).

4. How many teeth do adults have? What are the four types of teeth and their function?

Adults have 32 teeth. Incisors for biting, canines for tearing, pre-molars for grinding, and molars for crushing.

5. What is a hydrolytic enzyme? What is the enzyme in saliva? What

reaction does it catalyze?

An enzyme that reacts water with a substrate to break it down. The enzyme in saliva is SALIVARY AMYLASE. It breaks starch down into the disaccharide MALTOSE.

6. Using a labeled diagram, explain why when you swallow food or liquid, it

doesn't usually go up your nose and down your windpipe.

The soft palate covers nasopharyngeal openings The trachea moves up and under the epiglottis PERISTALTIC waves move food down to the esophagus The soft palate keeps food from going up your nose and the epiglottis stops food from going down the trachea (wind pipe)

Ms.  Isenor     Name:_____________________________    

    Biology  12  Digestion  Workbook  

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7. Describe the process of peristalsis in the esophagus. How can a combination of circular and longitudinal muscles cause this action?

Circular muscles squeeze tubes, longitudinal muscles contract tubes to move food bolus along in a sequential fashion.

8. What are the functions of the stomach? Receives and temporarily stores food to be digested. Churns food to mechanically break it down, and produces pepsin which breaks proteins into peptides

9. What is gastric juice? Where is it produced? What is it composed of? What does it do?

A digestive juice containing enzymes, and which is produced by glands in the stomach mucosal lining. Contains pepsinogen and HCl. Pepsinogen and HCl combine to produce Pepsin, a hydrolytic enzyme that breaks proteins into peptides 10. Give a one sentence description, using your own words, of the function of the

following digestive components: Name Function

1. mouth

receive and chew food, moisten with saliva, and start to digest starch.

2. pharynx

Passageway for both air and food, leads to esophagus.

3. epiglottis

Cover opening to larynx when swallowing.

4. cardiac sphinctor

Muscle that encircles the esophagus at the stomach junction. Allows food into stomach, and also prevents constant vomiting.

5. esophagus

Moves food from mouth to stomach through peristaltic action.

6. pepsinogen

Protein precursor to pepsin, reacts with HCl to form pepsin.

11. How come, if your stomach is full of acid and protein-digesting enzymes,

doesn't it digest itself?  Thick mucus layer secreted by stomach wall protects it.          

Ms.  Isenor     Name:_____________________________    

    Biology  12  Digestion  Workbook  

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12. a) Majority of digestion takes place in this organ: The small intestine b) Structure of this organ: Long and convoluted b) Length of this organ: Very long / ~7m c) Three parts of this organ are called: duodenum, jejunum, and ilium 13. a) Length of the duodenum: A few inches b) What controls flow of material into the duodenum? Pyloric sphincter c) What is this material that enters the duodenum called? Chime / Chyme d) What is main role of duodenum in digestion? Inserts enzymes (amylase, trypsin, lipase, and nuclease), bile, and sodium bicarbonate (to neutralize acidic chime). e) What two organs produce secretions that end up in duodenum? Liver (gallbladder) and the pancreas 14. a) Liver produces what substance? Bile

b) Where is this substance stored? The gall bladder 15. What does bile do? Bile emulsifies fat. Breaking large fat droplets into smaller fat droplets (mechanical)

16. a) What compound does pancreatic juice contain? Sodium Bicarbonate

b) What does this substance do? It neutralizes the acidic chime. From pH 2 or 3 to pH 8 or 9

c) What 3 important enzymes does pancreatic juice contain (name and function)?

Pancreatic Amylase: starch à maltose Trypsin: Protein à peptides Lipase: Lipids à fatty acids and glycerol

Ms.  Isenor     Name:_____________________________    

    Biology  12  Digestion  Workbook  

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17. a) What produces the intestinal juices in the small intestine? Intestinal crypts or Intestinal glands b) Where are these glands located? Within/beside villi in the sm. Intestine (ilium

and jejunum)

c) Two important intestinal juice enzymes and their functions are (name and function): Maltase: Maltose à glucose Peptidase: Peptides à amino acids Nuclease: Nucleic acids à nucleotides

18. a) Draw a villus, and show the blood and lymph vessels within.

19. a) Where does absorption take place? Absorption of nutrients mainly in ileum, but jejunum too. Absorption of water in the lg. intestine.

b) Where do sugars and amino acids go? Into your blood stream c) Where do glycerol and fatty acids go? Into the lacteal in your lymph system

Ms.  Isenor     Name:_____________________________    

    Biology  12  Digestion  Workbook  

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20. List 6 functions of the liver

� Production of bile � Glucose à Glycogen, and back again � Destruction of old RBC � Storing iron and vitamins � Making plasma proteins � Producing urea (from ammonia) � Detoxifying metabolic wastes

21. Explain how the large intestine is structurally and functionally different from the small intestine.  The  large  intestine  is  shorter  and  pouchier  then  the  small  intestine,  and  does  not  contain  villi.  The  large  intestine  absorbs  water  from  the  stool  and  contains  e.coli.  This  e.coli  eat  undisgestable  food  (such  as  fiber)  and  produces  vitamins  aa’s  and  growth  factors.      The  small  intestine  is  long  and  convoluted,  containing  many  villi  for  large  surface  area.  The  small  intestine  secrets  enzymes  into  the  intestinal  tract  and  absorbs  nutrients  into  the  blood  and  lymph  system.      22.  What  are  the  three  main  types  of  hormones  regulating  the  digestive  process?  What  do  the  do?    

DID  NOT  HAVE  TO  DO  THIS  QUESTION  � Gastrin  

� High  concentrations  of  protein  in  stomach  cause  release  of  gastrin  

� Gastrin  causes  the  stomach  to  release  gastric  juices  � Secretin  and  Cholecystokinin  (CKK)  

� Acid  in  duodenum  (from  chime),  release  Secretin.  Fats  release  CKK  

� These  hormones  cause  increased  secretions  of  pancreas  and  liver.    

 23.  Trace  the  path  of  the  blood  from  the  small  intestine  to  the  heart.    Small  intestine  à  hepatic  portal  vein  à  liver  à  hepatic  vein  à  vena  cava  à  heart              

Ms.  Isenor     Name:_____________________________    

    Biology  12  Digestion  Workbook  

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     Using  the  diagram  above  explain  the  following:      24)  What  does  your  body  do  when  it  senses  a  high  blood  sugar  level?    High  blood  sugar  (glucose)  stimulates  your  pancreas  to  release  insulin.  The  insulin  travels  in  your  blood  stream  signaling  your  tissue  cells  to  become  more  permeable  to  glucose  (glucose  is  taken  up  by  cells).  Insulin  also  signals  for  the  liver  to  convert  glucose  into  glycogen  for  storage.  This  all  helps  to  lower  you  bodies  blood  glucose  levels.      25)  What  does  your  body  do  when  it  senses  a  low  blood  sugar  level?    Low  blood  sugar  (glucose)  stimulates  your  pancreas  to  release  glucagon.  This  glucagon  travels  in  your  blood  stream  to  your  liver  were  it  stimulates  the  liver  to  breakdown  glycogen  and  release  glucose  into  the  blood.  This  increases  your  bodies  blood  glucose  levels.            

Ms.  Isenor     Name:_____________________________    

    Biology  12  Digestion  Workbook  

  7  

DIGESTO-MAN Draw and label all the digestive parts and enzymes

Note: some descriptions are different in this diagram (enzymes called different things)