U6 - Digestion system

Question 1

Difference between chemical and physical digestion?

Answer 1

physical - mechanical reduction and movement of the food molecules into absorbable units
chemical - organic polymers are broken down by hydrolytic enzymes

Question 2

Proteins are broken down into absorbable components

Answer 2

short peptides ——> amino acids

Question 3

Carbohydrates are broken down into absorbable components

Answer 3

disaccharide ——–> monosaccharides

Question 4

Fats are broken down into absorbable components

Answer 4

glycerol + fatty acids

Question 5

Nucleic acids are broken down into

Answer 5

nucleotides

Question 6

Components of saliva

Answer 6

a. 99% water

b. also salivary amylase, an enzyme which
hydrolyses starch into maltose, and mucus

Question 7

The process of swallowing

Answer 7

1. tongue pushes food to the back of the
   mouth
2. epiglottis contracts and folds down to close
   the opening to the trachea
3. tongue pushes food further back into the
   pharynx, and food enters esophagus

4, epiglottis relaxes and opens the trachea

Question 8

Describe peristalsis

Answer 8

rhythmic contraction of muscles

propelling food through the digestive tract

Question 9

components of gastric juice

Answer 9

hydrochloric acid – produces a pH of about
2, breaks down food, kills most bacteria

pepsinogen – in acid becomes pepsin,
enzyme which hydrolyses protein into shorter
polypeptides

Question 10

Sphincters at entrance at exit of stomach

Answer 10

cardiac sphincter – allows food in from
esophagus, closes to prevent acidic stomach
contents from moving back up

pyloric sphincter – opens and closes to
control movement of food into the
duodenum, first part of the small intestine

Question 11

Functions of the liver

Answer 11

1. production of bile – bile emulsifies fat by
   breaking it into smaller droplets, stored in
   the gall bladder until needed
2. storage of nutrients – glycogen, fat-soluble
   vitamins, and minerals
3. nutrient metabolism – metabolism of
   carbohydrates, proteins, and lipids
4. detoxification of blood – drugs and toxins,
   such as alcohol, are filtered out of the blood
5. production of blood protein – albumin
   maintains the tonicity of blood plasma
6. removal of red blood cells – old or damaged
   RBC’s are filtered out and the haemoglobin
   in them is converted into bile pigments

Question 12

Why are liver and pancreas called accessory organs?

Answer 12

because they produce
digestive secretions but never touch the
food

Question 13

How is bile involved in digestion of lipids

Answer 13

bile emulsifies fat by
breaking it into smaller droplets, stored in
the gall bladder until needed

Question 14

Components of pancreatic juice

Answer 14

lipase – enzyme hydrolyses lipids into glycerol
and fatty acids

pancreatic amylase – enzyme hydrolyses starch
into maltose

trypsin – enzyme hydrolyses protein into shorter
polypeptides

nuclease – enzyme hydrolyses nucleic acids
(DNA and RNA) into nucleotides

sodium bicarbonate – base to neutralise the
acid from gastric juice, produces a pH around 8

Question 15

Components of intestinal juice

Answer 15

maltase – enzyme hydrolyses maltose into
glucose

peptidase – enzyme hydrolyses short
polypeptides into amino acids

mucus – lubricates and protects the intestinal
wall

Question 16

How is Small Intestine specialized for digestion and absorption?

Answer 16

• secretes intestinal juice to finish chemical

digestion

Question 17

three regions of small intestine?

Answer 17

duodenum – most chemical digestion
occurs here, receives secretions of liver
and pancreas

jejunum – longest region, most
absorption occurs here

ileum – finishes absorption

Question 18

What is a villus

Answer 18

lol

Question 19

What are microvilli

Answer 19

• cells lining the villus are covered with many

tiny extensions

Question 20

how are monosaccharides and amino acids absorbed into the body?

Answer 20

• these are actively transported into the cells
  lining the villus
• they then pass by facilitated diffusion into the
  the tissue fluid, and from there diffuse into the
  villus capillaries that lead to the hepatic portal
  vein

Question 21

what happens to fatty acids and glycerol?

Answer 21

these diffuse into the cells of the villus, where
they are converted back into lipids

these are packaged into vesicles and
released via exocytosis

vesicles pass into the lacteal and are carried
through the lymphatic system to the liver

Question 22

Blood vessel that takes monosaccharide sugars and amino acids to the liver?

Answer 22

Hepatic Portal Vein

• carries blood from the small intestine
  to the liver, where it is processed
• portal vessels have the anatomy of a vein,
  even though they do not connect to the heart

Question 23

Large and small intestine size and length

Answer 23

Large - 1.5 m in length, but big diameter

Small - small in diameter, long in length

Question 24

Function of colon

Answer 24

the ileum of the small intestine connects to
the colon, the main part of the large intestine.
- prepares food for elimination

Question 25

Function of rectum

Answer 25

- large intestine ends in a short, expandable region called the rectum - food that has passed through the entire digestive tract, now called feces, is stored here until it can be eliminated

Question 26

Function of appendix

Answer 26

Narrow pouch assets in maintenance of gut bacteria

Question 27

Order of organs and structures of digestive system

Answer 27

mouth-pharynx-esophagus-stomach-duodenum-ljejunum-ileum-colom-rectu-anus

Question 28

Hormone that comes from pancreas and maintains blood sugar levels?

Answer 28

in addition to digestive secretions, the pancreas also secretes the hormone insulin insulin is released when blood glucose levels are high, usually after eating insulin stimulates muscle and liver cells to store glucose as glycogen this causes glucose levels to decrease, an example of negative feedback

Question 29

function of e/coli bacteria in colon?

Answer 29

- colon is home to populations of anaerobic bacteria, bacteria that live without oxygen - the metabolism of these bacteria produces beneficial molecules, such as vitamins K and B7, as well as flatulence and the odour of feces

Question 30

Proteases (pepsin, trypsin)

Answer 30

Source = pepsin – stomach, trypsin - pancreas Site of action = pepsin – stomach, trypsin – small intestine Optimum pH = pepsin – acidic (2), trypsin – basic (8) Function = protein + H2O → polypeptides

Question 31

Salivary amylase

Answer 31

Source = salivary glands Site of action = mouth Optimum pH = neutral (7) Function = starch + H2O → maltose

Question 32

Lipase

Answer 32

Source = pancreas Site of action = small intestine Optimum pH = basic (8) Function = lipids + H2O → glycerol + fatty acids

Question 33

Nuclease

Answer 33

Source = pancreas Site of action = small intestine Optimum pH = basic (8) Function = nucleic acids + H2O → nucleotides

Question 34

Pancreatic amylase

Answer 34

Source = pancreas Site of action = small intestine Optimum pH = basic (8) Function = starch + H2O → maltose

Question 35

Peptidase

Answer 35

Source = small intestine Site of action = small intestine Optimum pH = basic (8) Function = polypeptides + H2O → amino acids

Question 36

Maltase

Answer 36

Source = small intestine Site of action = small intestine Optimum pH = basic (8) Function = maltose + H2O → glucose + glucose

Question 37

steps of digestions

Answer 37

physical digestion: chewing, mixing, moving chemical digestion: breaking down food molecules into absorbable units secretion: fluids, enzymes, hormones, bile, mucus absorption: through tract wall into blood or lymph vessels elimination: undigested material expelled

Question 38

pharynx

Answer 38

- common passageway for air and food behind the mouth - contains the epiglottis, a muscular flap involved in swallowing

Question 39

esophagus

Answer 39

carries food to stomach

Question 40

trachea

Answer 40

air passage to lungs

Question 41

esophagus

Answer 41

- long muscular tube connecting pharynx to stomach - lined by mucus secreting cells that lubricate the walls and assist the passage of food

Question 42

liver, pancreas placement

Answer 42

two other digestive organs are connected by narrow ducts to the duodenum: liver – above and beside the stomach pancreas – between the stomach and the intestine