Gi tract

Question 1

What is malabsorption?

Answer 1

Difficulty in digestion and absorption of nutrients from food, can be caused by illnesses such as cf.

Question 2

Name a secretion within saliva.

Answer 2

Amylase, mucus or lysozyme.

Digest carbohydrates.

Question 3

Name a gastric juice involved in carbohydrate digestion.

Answer 3

HCL, pepsin, mucus and intrinsic factor.

Question 4

Name a pancreatic digestive enzyme.

Answer 4

Trypsin, chymotrypsin, amylase and lipase.

Question 5

Name accessory digestive organs.

Answer 5

Salivary glands, exocrine pancreas (secretion of digestive enzymes) and biliary system (store, secrete and transport bile).

Question 6

What are the 4 layers of the digestive tract?

Answer 6

Mucosa
Submucosa
Muscularis externa
Serosa

Question 7

What nervous system is the digestive tract?

Answer 7

The enteric nervous system.
The GI tract uses autonomous smooth muscle function.
And uses the parasympathetic (rest and digest) and sympathetic (fight or flight) nervous systems.

Question 8

Receptor activation alters digestive activity, what are the main receptors involved in the neural and hormonal pathways?

Answer 8

Chemoreceptors 
Mechanoreceptors 
Osmoreceptors 
\:
which are capable of detecting mechanical, chemical, and osmotic stimuli/changes.

Question 9

What is the start of the GI tract?

Answer 9

Oral cavity (mouth) is the entrance.
Proceeds with mastication (grinding of teeth etc), which begins the break down of food.

Question 10

What is the purpose of saliva?

Answer 10

Begins carbohydrate digestion as contains hydrolytic enzymes.
Helps swallowing, speech, taste and oral health.

Question 11

What is saliva made up of?

Answer 11

99.5% h20 and 0.5% electrolytes and protein.

Question 12

What are the 5 main electrolytes in body fluid?

Answer 12

Sodium, Chlorine, Magnesium, Calcium and Potassium.

Question 13

What are the 3 pairs of salivary glands?

Answer 13

Parotid
Submandibular
Sublingual

Question 14

What are the two main cells that comprise the salivary glands?

Answer 14

Serous cells (contain zymogen granules which are involved in the secretion of digestive enzymes)
Mucous cells (secrete mucous)

Question 15

Describe the neural pathway involved in salivary secretion.

Answer 15

Mechanical/pressure and chemo. receptors in the mouth.
Thinking, seeing and smelling food in cerebral cortex.
Mouth and cerebral cortex send action potentials too salivary centre in medulla.
Action potentials in autonomic (involuntary nervous pathway) nerves.
Stimulate salivary glands, saliva is secreted.

Question 16

What are the 3 phases of oesophageal peristalsis (swallowing)?

Answer 16

Medulla innervates muscles in pharynx.
Upper oesophageal sphincter closes.
Larynx closes, glottis opens.
Food then passes through, via muscle contractions, the lower oesophageal sphincter, into the stomach.

Question 17

Where does gastric mixing take place?

Answer 17

Antrum of the stomach, via repulsion of the chyme.

Question 18

How does the stomach protect against acid injury.

Answer 18

Mucous lines the stomach wall.

Question 19

How is small intestine segmentation contraction involved in the digestive process.

Answer 19

BER (basal electrical rhythm), from pacemaker cells, cause the small intestine muscles to contact.
These contractions mix the chyme with digestive juices within the intestine, as well as propel the chyme.
The chyme is then absorbed by the small intestine mucosa.

Question 20

How does the small intestine further digest chyme?

Answer 20

Digestive enzymes act intracellularly within the brush-boarder membrane of epithelial cells (lining the lumen).

Question 21

Describe the carbohydrate digestion of Starch/glycogen.

Answer 21

Polysaccharides Starch/glycogen is broken down into Maltose by salivary amylase/pancreatic amylase.
Disaccharide Maltose is then broken down into 2 glucose monomers, via maltase, intracellularly via the small intestine epithelial brush boarder.

Question 22

Describe the carbohydrate digestion of Lactose.

Answer 22

Disaccharide lactose is broken down via Lactase, into monomers galactose and glucose, intracellularly via the small intestine epithelial brush boarder.

Question 23

Describe the carbohydrate digestion of Sucrose.

Answer 23

Disaccharide Sucrose is broken down into monomers glucose and fructose, via sucrose isomaltase, within the small intestine intracellularly via the epithelial brush boarder.