Digestive system + metabolism

Question 1

Functions of the digestive system

Answer 1

Ingestion, Secretion, Mechanical Processing, Digestion, Absorption, Defecation

Question 2

layers of the digestive tract

Answer 2

1. mucosa (inner lining), 2. submucose (connective tissue),
2. muscularis externa (smooth muscle)
3. serosa (outer covering)

Question 3

Digestive organs and functions

Answer 3

1. oral cavity: ingetsion, sensory analysis
2. stomach: temporary storage, mixing, digestion begins
3. small intestine: duodenum (receives chyme), jejunum (digestion + absorption), Ileum (connects to cecum)
4. large intestine: water + vitamin reabsorption
5. liver: metabolism
6. Gall bladder: stores / concentrates bile
7. Pancreas: endocrine (insulin/glucagon), exocrine (digestive enzymes)

Question 4

mechanical digestion organs

Answer 4

1. Mouth: mastication (teeth, tongue, palate)
2. Oesophagus: peristalsis (waves of contraction)
3. Stomach: mixing, churning, peristalsis
4. small intestine (segmentation (mixing), peristalsis (propulsion)

Question 5

Absorption and transport through the digestive system the 4 factors

Answer 5

1. Absorption: movement into interstitial fluid, blood or lymph
2. Small intestine: 90% absorption due to villu, microvilli, mucosa movement
3. Transport mechanisms: simple diffusion, facilitated diffusion, contransport, active transport
4. Hepatic portal system: nutrients from gut travel to liver for processing

Question 6

Absorption of nutrients in digestive system

Answer 6

1. proteins: amino acids - liver - protein synthesis or converted to carbs/lipids
2. carbs: monosaccharides - liver - glucose synthesis/storage
3. lipids: monoglycerides + fatty acids - micelles - chylomicrons - lymph - venous system
4. vitamins & ions: absorbed via specialised mechanisms
5. water: passive osmotic flow

Question 7

defecation reflex in the digestive system

Answer 7

rectal wall stretch triggers reflex - internal sphincter relaxes. brain controls external sphincter voluntarily. Constipation = slow transit, Diarrhoea = fast transit

Question 8

Metabolism basics in digestive system

Answer 8

Metabolism: sum of all biochemical reactions
Catabolism: Breakdown of molecules - energy release
Anabolism: building molecules - energy use
ATP: Main energy currency

Question 9

Glucose metabolism in digestive system

Answer 9

Glycolysis: glucose - pyvurate
Krebs Cycle: Pyvurate - Acetyl
Total ATP: approx 30-32 ATP per glucose

Question 10

Glycogenesis

Answer 10

Glucose - glycogen (storage), insulin-triggered

Question 11

Glycogenolysis

Answer 11

glycogen - glucose, triggered by glucagon and adrenaline

Question 12

Gluconeogenesis

Answer 12

New glucose from non-carbs, triggered by cortisol and glucagon

Question 13

what is lipolysis

Answer 13

triglycerides - glycerol (krebs) & fatty acids

Question 14

what is lipogenesis

Answer 14

excess nutrients - triglycerides (insulin-triggered)

Question 15

What is catabolism

Answer 15

energy production if needed

Question 16

anabolism

Answer 16

protein synthesis

Question 17

Metabolic states: what is absorptive (Fed):

Answer 17

anabolism > catabolism. Insulin promotes glucose uptake, glycogen, protein and fat synthesis

Question 18

Metabolic states: post-absorptive (fasting):

Answer 18

catabolism > anabolism. Glucagon stimulates glycogenolysis, gluconeogenesis to maintain BGL

Question 19

what is BMR

Answer 19

minimum energy at rest, influenced by lean mass, sex, age, body temp, food, exercise, hormones

Question 20

thyroid hormone

Answer 20

increases mitochondrial ATP production and metabolic rate

Question 21

Adrenaline / Noradrenaline

Answer 21

raise BMR under stress