8 - Digestive system

Question 1

carbohydrate monomers (2)

Answer 1

1. glucose
2. fructose

Question 2

protein monomers

Answer 2

amino acids

Question 3

neutral fat monomers (2)

Answer 3

1. fatty acids
2. glycerol

Question 4

what are carbs, proteins and fats carried in?

Answer 4

blood plasma

Question 5

what break down proteins?

Answer 5

digestive enzymes in gastrointestinal tract (alimentary canal)

Question 6

how can amino acids be used to generate ATP?

Answer 6

some types of amino acids can enter TCA cycle (Krebs cycle) after small modifications and be used as fuel to generate ATP

Question 7

role of large intestine (2)

Answer 7

1. absorption of water molecules and ions
2. formation/storage of faeces

Question 7

role of small intestine (2)

Answer 7

1. duodenum receives chyme from stomach and mixes it with pancreatic enzymes
2. absorption of nutrients (glucose/amino acids)

Question 8

what are the veins of the small/large intestine enriched with respectively?

Answer 8

1. Small intestine - glucose and amino acids
2. Large intestine - ions

Question 9

role of liver in absorption of nutrients from small intestine (4)

Answer 9

1. nutrients absorbed by walls of s.intestine, pass through liver
2. liver filters, can remove potentially harmful elements before systemic circulation
3. hepatocytes (liver cells) store excess nutrients
4. blood returning to right atrium/ventricle via inferior vena cava enriched in glucose and amino acids

Question 10

Hepatic portal system (liver 3-way blood flow) (3)

Answer 10

1. oxygenated arterial blood (hepatic artery)
2. venous blood carrying deoxygenated blood (hepatic vein)
3. nutrient rich blood from hepatic portal vein (hepatic portal vein)

Question 11

how are fatty acids transported?

Answer 11

lymphatic system via lacteal (specialised lymphatic capillary)

Question 12

5 purposes of digestion (5)

Answer 12

1. ingestion/breakdown of food (mechanically/chemically)
2. secretion of enzymes into alimentary canal
3. digestion of chyme by enzymes that break polymers (carbohydrates, protein and fats) down to respective monomers
4. absorption of glucose, amino acids and fatty acids from lumen of s.intestine via epithelial cells -> CVS
   - absorption of ions and H2O molecules from l.intestines -> CVS
5. remaining faeces excreted

Question 13

role of upper and lower oesophageal sphincters (2)

Answer 13

1. if not relaxed properly food fails to enter stomach as it should and causes obstruction
2. incompetence lower oesophageal sphincter - gastric juices move back up into oesophagus and cause erosion of mucosa

Question 14

4 major parts of stomach (4)
(fuck boobs and pusy)

Answer 14

1. fundus - capable of receptive relaxation
2. body - 3 layers of muscles, initiate mixing waves
3. antrum - strong contractions, thorough mixing of chyme
4. pyloric sphincter (pylorus) - usually tightly shut

Question 15

migrating motor complex (MMC)

Answer 15

sequence of contractions begin the emptying of stomach and end in large intestines (one cycle approx 90min)

Question 16

2 components of basic gut movement (2)

Answer 16

1. segmentation
2. peristalsis

Question 17

segmentation

Answer 17

closely spaced contractions of smooth muscle circular movement followed by relaxation

Question 18

peristalsis

Answer 18

triggered by distension of gut by food. longitudinal smooth muscle contracts first, followed halfway through contraction by circular muscle, longitudinal relaxes during latter half of circular contraction (leads to progressive wave)

Question 19

where does segmentation occur and what is its purpose? (2)

Answer 19

1. mainly in small intestine
2. mixes food with enzymes

Question 20

motility in large intestine (5)

Answer 20

1. when receiving chyme, receptive relaxation of caecum (pouch at beginning of l.intestine) occurs, smooth muscle cells of ascending colon (first section of l.intestine) elongate lengthways, letting chyme in
2. ascending/descending colons make peristaltic movements
3. in ascending colon, chyme makes natural pouch-like shape due to revers peristalsis
4. transverse (middle section of l.intestine) makes short wave peristalsis, propels material slowly
5. descending colon (end of l.intestine) can make extended peristaltic contraction, results in mass movement of faeces
6. when mass movement empties faecal material into rectum, induces sensation to defecate

Question 21

3 sections of small intestine (3)

Answer 21

1. duodenum
2. jejunum
3. ileum

Question 22

5 sections of large intestine (5)

Answer 22

1. caecum
2. ascending colon
3. transverse colon
4. descending colon
5. rectum

Question 23

describe the motion of the stomach and small intestine and the movement of chyme (4)

Answer 23

1. ingested food mixed with water, stomach acid and digestive enzymes, becomes chyme in stomach
2. stomach antrum (lower portion of stomach near outlet) and pyloric sphincter (ring of smooth muscle - valve between stomach and s.intestine) function in coordinated manner and control exit of chyme from stomach
3. chyme enters duodenum and progresses to jejunum and ileum by 2 distinct motions - segmentation and peristatic contractions
4. chyme leaves s.intestine and enters caecum (connects s.intestine to l.intestine) via ileo-caecal sphincter

Question 24

describe the generalised structure of the gastrointestinal tract wall (4)

Answer 24

1. inner layer - epithelial layer and mucosa (mucous membrane) 2. middle layers - smooth muscle layers (circular/longitudinal) 3. nervous tissue - enteric nervous system (neuron network in gastrointestinal tract) 4. immune system cells on patrol

Question 25

digestive system auxiliary organs and secretory tissue (5)

Answer 25

1. mouth 2. stomach 3. pancreas 4. liver 5. gall bladder

Question 26

exocrine cells (2)

Answer 26

1. all glands are exocrine cells 2. produce secretions

Question 27

examples of secretions of exocrine cells (4)

Answer 27

1. bicarbonate ion 2. water 3. mucus 4. digestive enzymes

Question 28

mouth salivary glands (exocrine cells) (3)

Answer 28

1. serous acini 2. mucus acini 3. duct cells

Question 29

pancreas secretions

Answer 29

enzymes

Question 30

pancreas exocrine cells

Answer 30

acinar cells - secrete digestive enzymes (channeled via exocrine duct leading to digestive tract)

Question 31

pancreas endocrine cells

Answer 31

langerhans islet cells - secrete hormones that enter the blood

Question 32

gall bladder

Answer 32

stores bile acids secreted from liver