2. Digestive Systems- Comparative Anatomy

Question 1

Why does the body need nutrients?

Answer 1

Growth, Repair, Maintenance, Energy supply, Reproduction

Question 2

What is the general process of digestion?

Answer 2

The food is ingested, then digested and broken down by an enzymatic process into small chemical units.

The absorbed chemical units are carried to the liver where they are metabolised for use by the body.

Any indigestible material is excreted from the body.

Question 3

What types of animals are there (based on their digestive system)?

Answer 3

Carnivore, omnivore, browser, herbivore

Question 4

What are the anatomical differences of the tongue in the dog, cat, goat and bird?

Answer 4

Dog- stretch receptors in the tongue and can use the tongue to lose heat (panting)

Goat- heavily keratinised with long papillae for eating (protective surface)

Cat- long papillae for grooming

Bird- contains a bone used for food manipulation. Parrots use tongue to produce sound

Question 5

What is the Buccal cavity and how is it used in different animals?

Answer 5

A cavity lying within the mouth (cheeks)

Rodents- cheek pouches to store food

Ruminants- papillae are present on the medial surface of the cheeks to provide protection to the underlying epithelium due to diet

Question 6

What anatomical differences are there to the soft palate in equine, canine and avian species?

Answer 6

Equine- tight laryngeal cuff so that the soft palette can not be raised for a long period of time- prevents vomiting

Canine- soft palate can obstruct breathing in brachycephalic breeds

Avian- birds lack a soft palate

Question 7

What components make up saliva?

Answer 7

Water, inorganic salts, mucin, salivary analyse, electrolytes, antimicrobial agents, lingual lipase

Question 8

How much saliva do animals produce in a 24hr period?

Answer 8

Equine- 40L

Bovine (cattle)- 110-180L

Porcine (pigs)- 15L

Question 9

What are the 3 types of digestive system?

Answer 9

Mono gastric- carnivores and omnivores

Ruminant- herbivore and browses

Hind gut fermenter- herbivore and browser

Question 10

What is Proteases and how/where are they secreted?

Answer 10

Pepsinogen-Secreted as an inactive sumo hen, activated by hydrochloride acid; active pepsin produces and completed near brush border to generate small peptides and individual amino acids; starts in the stomach and continues into the small intestine.

Question 11

What are carbohydrase and where/how are they secreted?

Answer 11

Eg Amylase are within salivary and pancreatic secretions and act to produce disaccharides; disaccharides are converted to monosaccharides near the brush border

Question 12

What are lipases and how/where are they secreted?

Answer 12

Assisted by bile salts which neutralise stomach acids and emulsified fats- process generates free fatty acids

Question 13

What is the small intestine responsible for?

Answer 13

Main site of chemical degradation and absorption of chyme, breaks down fats, absorbs starch, lipids and proteins

Question 14

What is the pancreas made of and what is the role?

Answer 14

It is a pink lobulated mixed gland made up of Islets of langerhans.

It secreted exocrine (enzymes) and endocrine (hormones)

Question 15

What makes up pancreatic juices?

Answer 15

Produced by the exocrine part in a response to gastrin (from stomach) and secretin (from duodenum)

Contains:

• Bicarbonate (neutralise acid in chyme)
• Digestive enzymes
• Proteases
• Lipases
• Amylases

Question 16

Which animals have a caecum and why?

Answer 16

Herbivores/ruminants

Houses fermenting bacteria to breakdown cellulose

Question 17

What is the function of the large intestine?

Answer 17

• Absorption of water
• Absorption of water soluble vitamins (B&C)
• Storage of faeces
• Mass movement of faeces through the descending colon stimulating defaecation

Question 18

What is the role of the Rectum?

Answer 18

Although empty most of the time, the rectum holds the faeces before defecation

Question 19

What is the anus made up of?

Answer 19

Internal anal sphincter- smooth muscle, involuntary

External anal sphincter- striated muscle, voluntary

Question 20

What is different about avian anatomy?

Answer 20

Mouth- no teeth, crop, proventriculus, gizzard and cloaca

Question 21

What is the role of the crop?

Answer 21

To store food and water until ready to be passed to the rest of the GI tract. When empty it stimulates the bird to eat more

Question 22

What is the role of the proventriculus?

Answer 22

True stomach where digestion begins. HCl and digestive enzymes break down feed further than the enzymes secreted in salivary glands

Question 23

What is the role of the gizzard?

Answer 23

Mechanical breakdown - made up of two sets of strong muscle that act as teeth

Question 24

What is the role of the cloaca?

Answer 24

Digestive and urinary waste mix together to be excreted. Also the exit of the reproductive tract

Question 25

How is feeding controlled?

Answer 25

Hormones, neurotransmitters and reflexes are involved in the feeding of animals.

Secretions and motility of the GI tract are stimulated and regulated by numerous factors, including environmental stimuli and the presence of food in different parts of the GI tract.

When a harmful substance is ingested, the body acts to eliminate it in different ways to prevent illness eg vomit or diarrhoea