digestive system

Question 1

mouth

Answer 1

• food is ingested and teeth begin mechanical breakdown of food into smaller pieces
• tongue pushes food against hard palate (roof of mouth) to further break food into smaller pieces
• salivary glands secrete saliva

Question 2

saliva contains…

Answer 2

• mucus to make the food slippery for swallowing
• the hydrolytic enzyme salivary amylase which begins the chemical breakdown of starch into maltose (disaccharide) making the food taste sweet and better

Question 3

tongue

Answer 3

• pushes food to pharynx which starts the swallowing reflex, food is called a bolus

Question 4

swallowing reflex

Answer 4

• as bolus is swallowed, soft palette pushes upward to close the nasal cavity
• uvula is small flap that projects down into the pharynx and “kicks” food away from nasal cavity
• epiglottis closes entrance to trachea so that food doesn’t enter there

Question 5

esophagus

Answer 5

• a muscular tube which leads to the stomach
• wave-like contractions called peristalsis of the smooth muscle which surrounds the esophagus pushes food towards stomach
• at stomach entrance, cardiac sphincter (a ring of muscle) prevents food from leaving stomach and entering esophagus

Question 6

heartburn occurs when…

Answer 6

• acid from the stomach escapes through the cardiac sphincter into the unprotected esophagus

Question 7

stomach

Answer 7

• food enters stomach, gastric glands of stomach secrete gastric juice

Question 8

gastric juice contains…

Answer 8

• hydrochloric acid, which creates acidic environment of stomach (pH 3). acidic environment kills bacteria in food but mainly functions to convert the inactive enzyme pepsinogen into the active enzyme pepsin
• mucus coats stomach wall protecting the cells from HCl
• pepsinogen. pepsinogen + HCl = pepsin. pepsin begins breakdown of protein into peptides.

Question 9

ulcer is caused by…

Answer 9

• digestion of proteins in stomach (gastric) cell membranes, effectively “eating” a hole in the stomach lining (caused mainly by bacteria, NOT excess stomach acid)

Question 10

food leaving stomach is called…

Answer 10

• acid chyme = travels out of stomach through pyloric sphincter to small intestine

Question 11

small intestine (SI)

Answer 11

• duodenum = first part of SI where the rest of food is broken down by enzymes and the absorption of nutrients into blood begins
• as acid chyme (containing fats and partially digested protein) enters SI, liver increases production of bile and causes its release from gall bladder where it’s stored
• bile enters duodenum through duct where it emulsifies fat. this increases SA of fat for lipase to work

Question 12

pancreas

Answer 12

• secretes pancreatic juice which enters duodenum through pancreatic duct
• in the pancreas, the only foods to be completely broken down are fats

Question 13

pancreatic juice contains

Answer 13

SALT:

• sodium bicarbonate (NaHCO3)
• pancreatic amylase
• lipase
• trypsin

Question 14

sodium bicarbonate

Answer 14

• neutralizes acid chyme to pH of 8 and provides appropriate environment (pH) for the pancreatic enzymes amylase, lipase and trypsin

Question 15

pancreatic amylase function

Answer 15

• continues breakdown of starch to maltose (started in mouth)

Question 16

lipase function

Answer 16

• breaks down fats to fatty acids and glycerol which is helped by emulsification of fat into tiny droplets by bile (not an enzyme)

Question 17

trypsin function

Answer 17

• continues the breakdown of proteins into peptides which was started in the stomach.

Question 18

intestinal juice

Answer 18

• produced by cells lining the small intestine
• includes enzymes like peptidases that finish breakdown of protein. maltase also breaks down maltose into glucose here. lactase breaks down lactose into glucose too.
• also includes nucleases which break down nucleic acids into nucleotides

Question 19

someone who is lactose intolerant can’t produce___

Answer 19

lactase

Question 20

villi

Answer 20

• tiny folds in SA of SI. nutrients absorb through this. increases SA for absorption. fatty acids + glycerol diffuse into lacteal = part of lymphatic system which empties into blood stream. this prevents tiny capillaries in villi from clogging. glucose + amino acids (and vitamins + minerals) diffuse into these capillaries. glucose + amino acids can be actively transported to blood from SI, which allows transport from low to high concentration (against gradient). this ensures that blood absorbs max amount of glucose.

Question 21

colon

Answer 21

• remaining undigested materials travel into colon (aka large intestine)
• here, water + salt are absorbed and feces is compacted & temporarily stored
• helpful bacteria E. coli are found in colon where they break down some undigested material and produce vitamins & amino acids for our use
• undigested material is removed through defecation

Question 22

defecation

Answer 22

• removal of undigested material which has never entered the blood, and is technically different from excretion or removal of waste products from blood by kidneys

Question 23

liver

Answer 23

• produces bile, stored in gall bladder
• destroys old RBCs, converts hemoglobin breakdown products which become part of bile
• stores glucose as glycogen after eating, breaks down glycogen=>glucose between eating. this maintains blood glucose levels at ab 0.1%
• detoxifies blood by removing, metabolizing poisonous substances (alcohol)
• produces blood proteins (blood clotting ones)
• produces urea from the breakdown of amino acids = less toxic than NH3. rest of toxic amino acid is converted to glucose for emergency energy needs

Question 24

salivary amylase

Answer 24

• produced by salivary glands
• works in mouth
• substrate is starch
• product is maltose
• pH is 7-8

Question 25

pepsin

Answer 25

- produced by gastric glands - works in stomach - substrate is protein - product is peptides - pH is 2-3

Question 26

pancreatic amylase

Answer 26

- produced by pancreas - works in small intestine - substrate is starch - product is maltose - pH is 8

Question 27

lipase

Answer 27

- produced by pancreas - works in small intestine - substrate is lipids - product is fatty acids + glycerol - pH is 8

Question 28

trypsin

Answer 28

- produced by pancreas - works in small intestine - substrate is proteins - product is peptides - pH is 8

Question 29

peptidases

Answer 29

- produced by intestinal glands - works in small intestine - substrate is peptides - product is amino acids - pH is 8

Question 30

maltase

Answer 30

- produced by intestinal glands - works in small intestine - substrate is maltose - product is glucose - pH is 8

Question 31

nucleases

Answer 31

- produced by intestinal glands - works in small intestine - substrate is nucleic acids - product is nucleotides - pH is 8

Question 32

____ turns starch into maltose. | maltase turns ____ into ____

Answer 32

- amylase | - maltose, glucose

Question 33

_____ turn protein into peptides. | peptidases turn ____ into _____

Answer 33

- pepsin and trypsin | - peptides, amino acids

Question 34

is bile considered an enzyme?

Answer 34

- nahh

Question 35

lipase turns ____ into _____

Answer 35

- fats, fatty acids and glycerol

Question 36

____ turn nucleic acids into nucleotides

Answer 36

- nucleases

Question 37

what is uvula often mistaken for?

Answer 37

- the tonsilz

Question 38

4 phases of digestive process

Answer 38

- ingestion = includes swallowing and peristalsis - digestion = the physical and chemical breakdown of food - absorption = diffusion and active transport of nutrients into blood - defecation = removal of undigested material

Question 39

active transport is done by ___

Answer 39

- carrier proteins, which act like pumps

Question 40

where may peristalsis not occur? a) esophagus b) epiglottis c) small intestine d) stomach

Answer 40

b) epiglottis

Question 41

peptidases work in the a) stomach b) mouth c) esophagus d) small intestine

Answer 41

d) small intestine

Question 42

enzymes that work on all classes of food are secreted in the a) stomach b) pancreas c) small intestine d) liver

Answer 42

b) pancreas

Question 43

fatty acids and glycerol are first absorbed into the a) blood capillaries of the villi b) blood capillaries of the stomach c) lacteals d) lymph veins

Answer 43

c) lacteals

Question 44

absorption of digested food occurs largely in the a) liver b) stomach c) large intestine d) small intestine

Answer 44

d) small intestine

Question 45

what does lacteal do?

Answer 45

absorb fatty acid and glycerol

Question 46

insulin

Answer 46

- produced by pancreas - targets body cells, liver - causes body cells to increase uptake of glucose - causes liver to convert excess glucose to glycogen

Question 47

digestive system hormones

Answer 47

- gastrin is produced/works in stomach, controls secretion of gastric juices - secretin produced by pancreas, works in SI, controls production of pancreatic juice (SALT, insulin, glucagon) - CCK = hormone that works in fat digestion

Question 48

is pancreas both endocrine and exocrine?

Answer 48

- yeah, it produces hormones and enzymes/sodium bicarbonate

Question 49

which structure prevents food from entering nasal cavity?

Answer 49

- soft palate

Question 50

after products of digestion are absorbed, they travel through the blood stream to the ___

Answer 50

- liver

Question 51

nucleosidases

Answer 51

- produced in intestinal glands - works in small intestine - works on nucleotides - produces phosphate, pentose sugar and nitrogen base - ph is 8

Question 52

the digestive system order

Answer 52

1) mouth => pharynx2) esophagus 3) cardiac sphincter => stomach 4) pyloric sphincter => duodenum => small intestine (uses enzymes from pancreas and liver/gall bladder)/villi 5)absorbed stuff => liver, journey stops here. undigested stuff => colon 6) rectum 7) anus