Digesiton And Metabolism

Question 1

What’s in food

Answer 1

Macronutrients 
-carbohydrates, lipids, protein 
Micronutrients 
-vitamins and minerals 
Water and gases

Question 2

Segmentation

Answer 2

Circular muscles in small intestine contract to split up chyme and make bolus

Question 3

Peristalsis

Answer 3

Wave of contraction pushing bolus along

Question 4

Saliva

Answer 4

Amylase and lipase
Mucous
Antibodies and lysosomes

Question 5

The stomach

Answer 5

Circular, longitudinal and oblique muscles> churning
Sphincter at top and bottom
Contains HCl
Turns food into chyme, a partially digested food

Question 6

What’s in gastric juice

Answer 6

HCl> kill microbes and activate pepsin
Mucous> protect lining of stomach
Pepsin> digest proteins, activated by HCl (protease)
Gastric lipase> digest fats
Intrinsic factor> absorption of vitamin B12

Question 7

Pancreatic juice

Answer 7

Secretion stimulated by same thing that stimulates gastric activity- gastrin
Contains sodium bicarbonate - neutralise stomach acid
Enzymes

Question 8

Protease activated in the duodenum

Answer 8

Enzyme sticks to enterkinase> catabolic reaction> free active site

Question 9

What’s in bile

Answer 9

Bile salts 
-emulsify fats to enable lipids 
Bile pigment (Bilirubin)
-no role in digestion 
-rout of excretion 
Cholesterol 
-rout of excretion 
(Imbalance of salt/cholesterol may lead to stones)

Question 10

Hormones coordinating the function of the stomach and intestine

Answer 10

Cholecystokinin (CCK)

Secretin

Question 11

Cholecystokinin (CCK)

Answer 11

Arrival of chyme in duodenum 
>release of CCK by duodenal cells 
CCK travels to pancreas 
>secretion of enzyme rich juice 
CCK travels to gall bladder
>relax sphincter of Oddi> bile secretion 
CCK travels to liver
>production of more bile

Question 12

Secretin

Answer 12

Arrival of acid from chyme in duodenum
>secretion of secretin by duodenal cells
Secretin travels to pancreas
>secretion of sodium bicarbonate
» signal to inhibit further gastric activity

Question 13

Intestinal lining

Answer 13

Villi and microvilli

Peters patches> nodules of lymphatic tissue protecting GI tract from pathogens

Question 14

Liver

Answer 14

Receives products of ingestion via hepatic vein 
Detoxification/ biotransformation 
Storage of excess nutrients (glycogen)
Production of bile 
Destruction of old red blood cells

Question 15

Glucose> ATP

Answer 15

Anaerobic
1mol glucose > 2 ATP + pyruvate
Pyruvate goes through kerbs cycle = 2 ATP + NADH
Aerobic
NADH undergoes oxidative phosphorylation = +32ATP