Anatomy and Physiology of Digestion

Question 1

How has domestication led to a change in eating habits?

Answer 1

• horses are now fed small, concentrated meals
• this means they are not constantly consuming forage, as they have been naturally designed to do

In the field: 60% eating, 20% standing, 10% lying, 10% other

In the stable: 15% eating, 65% standing, 15% lying, 5% other activities

Question 2

What are the percentage components of the horse’s GIT?

Answer 2

The stomach makes up 8% of the GIT, 30% the S/I and 62% the hindgut.

Question 3

Define DIGESTION

Answer 3

Digestion is the process through which food is broken down

Question 4

Define ABSORPTION

Answer 4

Absorption is the transportation of food that has been digested into the bloodstream

Question 5

What does the food journey involve?

Answer 5

• the food enters the horse
• the food is broken down (digestion)
• the food being transported through the GIT and digested further
• the food being absorbed as it is transported through the GIT
• the food being metabolised into energy
• the food being excreted as waste when all the nutrients have been removed

Question 6

Where does all energy come from?

Answer 6

From the sun; all horses do is convert it.

Question 7

Describe the horse’s head and dentition

Answer 7

• have teeth that are well adapted to a lignified, fibrous diet
• the mandible (lower jaw) moved forward when the head is at ground level
• have a very strong, highly motile, sensitive upper lip
• incisors bite and molars chew
• have upper and lower incisors used for closely grazing

Question 8

Define SALIVA

Answer 8

Saliva is a colourless liquid produced by the paratoid, mandibular and sublingual glands. It is aids chewing and acts as a lubricant for digestion. Acts as a buffer for gastric juices as it is slightly alkali
Composition: 99% water, bicarbonate and NaCl. pH of 7

Question 9

What are the components of the foregut?

Answer 9

From the mouth, down the oesophagus, into the stomach and to the end of the small intestine

Question 10

What are the components of the hindgut?

Answer 10

The large intestine (the caecum and the large and small colon) anus.

Question 11

On average, how many jaw movements are there when eating concentrates compared with forage?

Answer 11

For horses:
1kg concentrates = 1000 jaw movements
1kg forage = 3000 jawmovements

For ponies:
1kg concentrates = 6500 jaw movements
1kg forage = 22500 jaw movements

Question 12

Describe the horse’s stomach

Answer 12

• has a capacity of 8l
• secretes 25l a day
• has a transit time of 2-6 hours
• has 4 regions - the oesophagal, cardiac, fundic and pyloric regions

Question 13

What are the three regions of the horse’s stomach?

Answer 13

Cardiac region (small in horses), the fundic region (main region, pH of about 5.4), pyloric region (pH of about 2)

Question 14

What are the three parts of the small intestine?

Answer 14

The duodenum, jejunum, ilieum

Question 15

What are the 4 secretions that come from the small intestine?

Answer 15

• duodenal juice (neutralzes things coming in)
• pancreatic juice (very enzyme rich)
• bile - breaks down large lumps of fat into small ones
• succus entericus

Question 16

Describe the horse’s hindgut

Answer 16

Very sensitive to change. Has a pH of 7. Celluose, hemicellulose and pectins are transformed into VFA. Anything not digested in the small intestine is digested here.

Question 17

What happens in the small colon?

Answer 17

Fecal formation begins and waste is excreted