chapter 9

Question 1

function of digestive system

Answer 1

extract nutrients from food we eat and transport them via blood to the cells where there are absorbed and used in chemical reactions

Question 2

the mouth

Answer 2

mechanical:
jaw and teeth cut, tear, crush and grind food
tongue mixes it up with mucus into a round lump called bolus

chemical:
salivary amylase ptyalin begins starch breakdown

Question 3

salivary glands

Answer 3

3 types, 2 of each

1. parotid salivary gained (front of ear)
2. sublingual salivary gland (under the tongue)
3. sub mandibular salivary gland (under mandible bone)

Question 4

upper jaw=

lower jaw=

Answer 4

maxilla

mandible

Question 5

types of teeth and their function

Answer 5

incisors: (4) biting and cutting, chisel shaped
canines: (2) tearing, pointy edge
premolars: (4) crushing and grinding
molars: (6) crushing and grinding
32 together

Question 6

tongue to stomach

food is swallowed

Answer 6

bolus is pushed into pharynx by tongue
oesophagus: made of mucosa, muscle (circular and longitudinal)
oesophagus pushes food from the mouth to the stomach by a wave of circular, muscular contractions called PERISTALSIS. movement lubricated by mucosa, prevents friction

Question 7

the stomach

Answer 7

after passing the diaphragm, the oesophagus reaches the stomach
mechanical:
waves of muscular contraction churns food and mixes it with gastric juices (HCl and enzymes) into thick soupy liquid called chyme
stomach has third muscle (oblique) to assist with churning

chemical:
gastric juices made in gastric glands of mucosa, contains enzyme pepsin (gastric protease) that begins protein breakdown. pepsin works in acidic conditions, that’s why it need activated by Hal to go from pepsinogen to pepsin
absorption: only alcohol and drugs absorbed in to blood

Question 8

stomach wall lining

Answer 8

deep folds called rugae line stomach to help it expand to increase volume
first is the cardiac sphincter then it is the pyloric sphincter
thick mucus walls

Question 9

stomach to small intestine

Answer 9

chyme goes into the duodenum (1st part of small intestine), through the pyloric sphincter (prevents food spilling into the duodenum too soon)
transferred by peristalsis (2-8hrs)

Question 10

3 parts of small intestine

Answer 10

1. duodenum
2. jejunum
3. ileum

Question 11

the duodenum and jejunum

Answer 11

mechanical:
waves of muscular contractions (L&C walls of small intestine),churn the food, peristalsis
bile stored in gall bladder, and made in liver, is secreted through duct and emulsifies fats

chemical:
pancreatic juices from the pancreas enter the duodenum (pH8) and neutralises the chyme, contains enzymes
- pancreatic protease: proteins to amino acids
-pancreatic amylase: carbohydrates to simple sugars
-pancreatic lipase: fats to fatty acids and glycerol
intestinal juice fro intestinal glands in the mucosa completely chemical digestion

Question 12

bile

Answer 12

emulsifies fats (breaks them down to tiny droplets, doest chemically change it)
has salts in it, not an enzyme
travels via duct to duodenum, helps neutralise chyme
increases surface area of fats so pancreatic lipase cancan quicker

Question 13

ileum/ small intestine

Answer 13

most products of digestion (V+M, H2O) are absorbed into the blood capillaries of the villi through diffusion, osmosi and active transport (depends on conc)
fast and fat soluble vitamins absorbed into the lacteals of the lymphatic system and transported to the chest, where they enter the blood and go to the liver
lacteals are permeable to larger fat molecules
villi and microvilli in small intesine increase surface area to increase absorption rate

Question 14

large surface area of small intestine

Answer 14

very long (6m)
inner mucosa lining has many folds
mucosa has villi on it, cells covering villi have further projections (microvilli)
has dense network of capillaries to absorb nutrients
epithelium is very thin (1 cell thick)

Question 15

ileum to large intestine

Answer 15

waste products of digestion go through large intestine
1.5 m long, no villi but mucosa is secreted to lubricate
bacteria breakdown remaining organic compounds
vitamins, minerals and water absorbed into blood, leaving contents semi-solid
faeces stored in rectum and eliminated through anus
faeces consists of, undigested cellulose, bacteria, bile, pigments, cells.
FUN FACT: cellulose stimulates movements of the alimentary canal.

Question 16

large intestine structure

Answer 16

caecum (appendix is attached)
appendix (lymphatic tissue)
ascending colon, transverse colon, descending colon
sigmoid colon
rectum anus

Question 17

what do gastric glands secrete

up to down

Answer 17

mucus
pepsinogen
Hal

Question 18

villi and absorption

Answer 18

fatty acids + glycerol: diffusion into lacteal

AA: active transport
water and water soluble vitamins: diffusion
simple sugars: active transport