5A: digestive system and physiology

Question 1

why is the ds needed?

Answer 1

• receive and move food, water and other materials
• process food in order to reduce size n structure
  -> physical disintegration aka mastication
  -> moisturising n lubrication
  -> biochemical breakdown
• absorption of digested components via gut membranes to blood vessels
  -> active transport
  -> passive diffusion
• synthesise molecules n nutrients for body tissues
• remove waste products

Question 2

how is the parasympathetic nervous system relevant to the ds?

Answer 2

• stimulates ds
• increases salivation, motility (diarrhoea)

Question 3

how is the sympathetic nervous system relevant to the ds?

Answer 3

• inhibits ds
• blood = ds to peripheral tissues??

Question 4

what components are part of the pre-gastric digestive tract? what are their individual roles in digestion?

Answer 4

• oral cavity -> biting/selecting food, chewing/grinding, lubrication
• pharynx -> facilitates food and air passage

Question 5

what are the components of the foregut and which roles do these play in digestion?

Answer 5

• oesophagus -> pushes/transports food
• stomach -> degrades, digests, absorbs
• first part of the duodenum -> further digestion and nutrient absorption

Question 6

what are the components of the mid gut and what roles do they play in digestion?

Answer 6

• latter part of duodenum -> further digestion n nutrient absorption
• small intestine -> propels degrades, digests, absorbs
• appendix -> produces and stores good microbes for the human gut
• part of caecum colon -> stores food material to break down cellulose

Question 7

what are components of the hindgut and what roles do they play in digestion?

Answer 7

• colon, rectum, anal canal -> ferments, adds/extracts fluid, stores, expels

Question 8

what are organs associated with the ds (but not directly part of it) and what part do they play in digestion?

Answer 8

• liver n gall bladder -> bile, hormones, storage
• pancreas -> enzymes, hormones, fluids, salts

Question 9

what is the function of the mouth and lip?

Answer 9

• select, bite, gather, n grasp food
• move food to oral cavity
• taste to select/reject food
• salivate to neutralise n lubricate food
• masticate food to form bolus

Question 10

what is prehension?

Answer 10

moving food into oral cavity

Question 11

what animals use forelimbs/tongue/lips/beaks for prehension?

Answer 11

forelimbs: dogs/humans
tongue: cow, sheep
lips: horse, pigs
beak: birds duhhh

Question 12

how do carnivore and herbivore teeth differ from each other?

Answer 12

carnivores: large canines n incisors
-> canines for tearing w less chewing
-> pointed molars for crushing bones
herbivores: stronger molars
-> chewing and grinding

Question 13

how do pseudo ruminants’ teeth/jaws distinguish themselves?

Answer 13

• incisors for biting
• angled molars
• circular jaw movements help grinding

Question 14

how do ruminants’ teeth/jaws distinguish themselves from others?

Answer 14

• no upper incisors
• strong dental pad
• molars w tongue n jaw movements
  -> help crush n chew food

Question 15

how much
do dogs/sheep/human/horse/cattle salvitate?

Answer 15

• dogs: just enough to lubricte
• sheep: 3-10l/d
• adult human: up to 1l/d
• horse: 10-15 l/d
• cattle: 120/200l/d

Question 16

what are the four parts of the foregut/stomach?

Answer 16

• reticulum
• rumen
• omasum
• abomasum