Digestive System + Physiology

Question 1

What is the digestive system

Answer 1

Long hollow tube
Shape + size changes between species

Question 2

Why is a digestive tract needed

Answer 2

To receive + move food, water + other materials
To process food to reduce size + structure
The remove waste products

Question 3

What are 3 ways to process food to reduce its size + structure

Answer 3

Physical disintegration
Moisturising + lubrication
Biochemical breakdown

Question 4

What are the 4 other relevant systems to the digestive system

Answer 4

Nervous + endocrine, respiration, skeleton + muscles, circulatory + excretory

Question 5

What are 4 components associated with the digestive tract

Answer 5

• mouth + oral cavity
• foregut ( oesophagus + stomach)
• mid gut (small intestine + appendix)
• hindgut (colon, rectum)

Question 6

What other components are associated with the digestive tract

Answer 6

• liver + gall bladder (bile + storage)
• pancreas (enzymes)

Question 7

What are the functions of the mouth and lip

Answer 7

• select / bite / gather food
• move food to oral cavity
• to select / reject food
• salivate to lubricate food
• masticate food to form bolus
  (Recieve, chew, move, swallow)

Question 9

Where does digestion start

Answer 9

In the mouth

Question 10

What is mastication

Answer 10

Grinding to reduce particle size - essential in non-ruminant herbivores + carnivores

Question 11

What are the species variations in carnivores

Answer 11

-Well developed teeth mostly for tearing with less chewing (canine + incisors)

Question 12

What are the species variations in herbivores

Answer 12

• strong molars to help chewing + grinding

Question 13

What type of teeth do pseudo ruminants have

Answer 13

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

Question 14

What type of teeth do ruminants have

Answer 14

• no upper incisors but string dental pad
  Molars with tongue + jaw movements help crush / chew food

Question 15

Describe the gut in birds

Answer 15

Crop = lower part of oesophagus = storage
Slowly digested when no new food is available

Question 16

Describe the foregut in mammals

Answer 16

• monogastric usually
• ruminants = multi gastric
• made up of reticulum, rumen, omasum + abomasum

Question 17

What is the similarities of front Vs hind gut fermenters

Answer 17

• both use microbes
• degrade + digest high fibre diets
• cellulose rich

Question 18

What type of animals have front gut fermentation

Answer 18

Ruminants

Question 19

Describe mid gut in carnivores + herbivores

Answer 19

• short in carnivores
• long in herbivores

Question 20

What are the enzyme variations in the mid gut functions

Answer 20

• Less sucrase, maltase + amylase in young Vs adult
• no sucrase in ruminants
• no lactase in adult pigs

Question 21

Fore gut VS hind gut fermentation

Answer 21

Foregut = more efficient per unit of food, slow digestion + size reduction
Hind gut = more efficient over time, faster turnover , coprophagy = food passes twice through DS

Question 22

What are 6 ruminant animals

Answer 22

Called
Sheep
Goat
Deer
Buffalo
camel

Question 23

Describe the mouth + oral cavity in ruminants digestive system

Answer 23

• receives stores grinds + moistens food
• buffering action = neutralises acidity due to fatty acids in rumen

Question 24

Describe the teeth, gums and jaw in ruminant animals

Answer 24

• grinds food to reduce particle size
• upper dental pad = no incisors
• lower jaw = incisors, premolars, molars

Question 25

Name 4 salivary glands in ruminants

Answer 25

Oral vestibule (cheek) = parotid , buccal Oral cavity proper (under tongue) = mandibular , sublingual

Question 26

What is the function of salivary glands in ruminants

Answer 26

- produces saliva - moistens food - protects the oral cavity + beyond - contains salts + HCO3 + mucous

Question 27

Describe the tongue in ruminants

Answer 27

- makes boluses of food - rough, hook line papillae = grasps + pulls food - taste buds = food avoidance

Question 28

Describe the ruminant stomach

Answer 28

- 4 compartments, rumen in 1st part then reticulum in 2nd - no clear partition - microbial fermentation not enzyme digestion - 3rd part = omasum - 4th part = abomasum

Question 29

Describe ruminant digestion

Answer 29

- rapid swallowing of food with no chewing - ingested feed moves to rumen - solid parts stay in rumen while liquids + solubles move to reticulum then omasum then abomasum

Question 30

What is the oesophageal grove in ruminants

Answer 30

- muscular folds that control passage of food to the omasum When closed = food directly enters from oesophagus to omasum When open = ingested food enters rumen + reticulum

Question 31

What is the benefit of the oesophageal grove to young nursing animals

Answer 31

They can bypass fermentation of their ingested milk

Question 32

What is rumination

Answer 32

Chewing the cud while sitting/standing when the rumen is full

Question 33

What is regurgitation

Answer 33

When the feed is forced back to the mouth for chewing, via many muscular contractions + movements

Question 34

What are the main bacteria that occupy the rumen + reticulum

Answer 34

-Streptococci - lactobacilli - fibrolytic - cellulolytic - proteolytic - amylolytic - lipolytic

Question 35

What is the function of the rumen

Answer 35

- receives breaks + processes food - fermentation vessel - microbes types change with the incoming food type - full of papillae that increase surface area for microbial attachment + absorption of fermented products - removes gases via belching

Question 36

What is the function of the reticulum

Answer 36

- similar microbial population - solid particles can be trapped here - regurgitation starts here - helps move food backward + forward to facilitate disintegration + fermentation

Question 38

What is the function of the omasum

Answer 38

- Strong muscle with many piles - grinds + squeezes the food - less / no digestion - removes water from incoming food - absorption of VFAS

Question 39

What is the function of the abomasum

Answer 39

- true similar - gastric juices added to undegraded feed - pH around 3 - food turns into slurry

Question 40

What enzymes are pancreatic secretions

Answer 40

- amylase - lipase - proteases

Question 41

What are factors affecting secretion

Answer 41

- secreted via the Bile duct - food as a slurry in duodenum - HCL + salts in duodenum stimulates the bile secretions

Question 42

Describe the large intestine in ruminants

Answer 42

- caecum, colon, rectum - hind gut fermentation - ammonia- N , mineral, water absorption

Question 43

Describe a monogastric tongue

Answer 43

- 8 muscles - extrinsic = attached to bones + change postion - intrinsic not attached to bones + changed to shape - papillae + taste buds - salivary glands

Question 44

What are the 3 types of salivary glands in mongastric and what do they secrete

Answer 44

Parotid - water, salts,ions, enzymes Submaxillary - mucin, enzymes, water Sublingual - mucin, enzymes, water

Question 46

Describe processes in the oesophagus (in horse/pigs and dogs)

Answer 46

- moves semi processed food from oral cavity to stomach - start of peristalsis = muscular contractions - horse/pigs = 2/3 striated muscles 1/3 smooth muscle - dogs = all striated

Question 47

What are the 4 basic layers of GIT

Answer 47

- mucosa - submucosa - muscularis - serosa