Organised disassembly and absorption Flashcards

1
Q

function of the oesophagus

A

transit

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2
Q

function of the stomach

A

storage
grinding food - milling
acid/peptic digestion

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3
Q

function of the small intestine

A

carbohydrate, fat, protein digestion and absorption
water and electrolyte transport
bile salt transport

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4
Q

function of the large intestine

A

storage

water reabsorption

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5
Q

function of the rectum and anus

A

defecation

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6
Q

what are the four digestive processes

A

motility
secretion
digestion
absorption

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7
Q

what occurs in the motility process

A

physically pass food through tract

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8
Q

what occurs in the secretion process

A

secrete digestive juices into digestive tract

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9
Q

what occurs in the digestion process

A

what you secrete will take the larger macromolecules and convert them into smaller molecules

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10
Q

what occurs in the absorption process

A

absorb efficiently and rapidly

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11
Q

what is apprehension

A

teeth, lips and tongue move food into the mouth

lips retain food in mouth

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12
Q

what is mastication

A

rhythmic action to break food to smaller pieces = increases SA

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13
Q

what is salivation

A

moistens food to make it easier to swallow

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14
Q

what is deglutition

A

swallowing, series of muscles facilitate pushing food to back of mouth

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15
Q

when is the somatic motor act initiated

A

by willed decision to start chewing

becomes automatic

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16
Q

what is the purpose of chewing food

A

grinds and breaks up food
mixes with saliva
stimulates taste buds = release chemicals

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17
Q

what hormone is released as a result of chewing and what is the effect this causes

A

gastrointestinal hormones
initial neurological activation
tell rest of gut food coming
whole process is controlled neurologically and hormonally

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18
Q

what are the three glands where saliva is secreted

A

parotids
sublinguals
submaxillary

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19
Q

what is secreted at the parotid gland

A

thin watery fluid

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20
Q

what is secreted at the sublinguals gland

A

fluid of intermediate viscosity

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21
Q

what is secreted at the submaxillary gland

A

thick, mucus-rich fluid

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22
Q

how is the saliva formed

A

all the secretions join to form enzyme and mucus-rich solution

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23
Q

what are the constituents of saliva

A

water 99.5% (solvent)
ions (sodium, chloride, bicarbonate-buffer)
mucus (lubricant-solvent)
alpha-amylase (enzyme attach starch-digestion)
lysozymes (destroy bacteria-first point of protection, antibacterial action)

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24
Q

what are the functions of saliva

A

aids speech - facilitate tongue movement
oral hygiene - flush food residues
buffering - bicarbonate buffers neutralise acids

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25
how many litres of saliva is secreted in a day
1-2
26
what controls saliva production
spontaneous | parasympathetic nerve endings
27
in response to a stimulus how much saliva can be produced
5ml per minute
28
which receptors respond to food in the mouth
chemoreceptors | pressure receptors
29
what happens at the salivary gland
1. neurological stimulus received via parasympathetic nerves 2. vasodilation of capillary = increase blood flow into capillary, more difficult for blood to flow continuously so increase pressure cause hyperfiltration of plasma filtrate of plasma passes between cells and enters lumen (acinus) 3. amylase vesicles move an fuse to the apical membrane, release enzyme contents same time bicarbonate is added from the acinar cells into fluid 4. NaCl ions removed from plasma in ductule so left with of watery fluid to pass down ductule
30
how many skeletal muscles are use in deglutition and what happens
25 | propel bolus into oesophagus
31
what is the name of movement along the oesophagus
active peristalsis
32
what is receptive relaxation
stomach expands to accepts food
33
what is the function of the stomach
acts as a storage vessel
34
what happens to food in the stomach
ingested material in strongly acidic medium (pH 2) weakens food structure digests protein with pepsin (optimum pH2)
35
what is the second wave of defence in boy
pH2 stomach acidic
36
how is chyme formed, what is chyme where does it go
in stomach during digestion turns the material into thin, acidic, slurry to be released into duodenum
37
what are the three layers of muscle in the stomach
oblique circular longitudinal
38
what is the function of the layers of muscle in the stomach
layers mean the bag can contract
39
what is the stomach lining like
mucosa is ridged - covered in ugae | further breaks the food
40
what is the gastic juice composed of
``` water HCl pepsinogen intrinsic factor mucous ```
41
what is the water for in the gastric juice
solvent
42
what is the HCl for in the gastric juice
chemical attack on food | antiseptic
43
what is the pepsinogen for in the gastric juice
pepsin secreted as pepsinogen (inactive precurser) | stomach acid activates pepsin
44
what is the intrinsic factor for in the gastric juice
essential for absorption of vitamin B12
45
what is the mucus for in the gastric juice
protects cells for further digestion
46
what cells make up the gastric gland
mucus parietal enteroendocrine chief
47
what is the function of the mucus secreting cells in the gastric gland
protect underlying cells
48
what is the function of the parietal cells in the gastric gland
secrete acid and intrinsic factor (need for vitamin B12 absorption in small intestine) only fundus and body
49
what is the function of the enteroendocrine cells in the gastric gland
secrete hormones into blood
50
what is the function of the chief cells in the gastric gland
secrete protein pepsinogen
51
how does the capillary link to the gastric gland
capillary diameter changed so plasma ultrafiltered out | produce fluid to enter gastric pit, in fluid the pepsinogen, acid and intrinsic factor mix into plasma
52
when are the enteroendocrine cells activated
when food enter stomach and stimulates gastric juice production
53
what can diffuse through an inactive parietal cell
chloride ions
54
what happens to the parietal cell when they are activated
they extend apical surface to long cannaliculi
55
when does carbonic acid form in parietal cell and how
when parietal cell activate | water and carbon dioxide diffuse IN to the cell from the capillary to form carbonic acid
56
what aids the formation of carbonic acid
carbonic anhydrase
57
what decreases the amount of acid made after digestion
inhibitors
58
what happens to carbonic acid produced in parietal cell
carbonic acid separates = hydrogen protons + bicarbonate proton pumps in apical membrane remove hydrogen protons into lumen of gastric pit using ATP bicarbonate diffuses OUT of cell back into circulation
59
what causes basic level of gastric secretion | what mechanisms is working
``` sight smell oral stimuli signals pass down vagal nerves, causes acetylcholine released signals to gastric pit neurological mechanism ```
60
what causes full wave of gastric secretion
when food enters stomach, hormonal mechanism
61
which are the hormones involved in gastric secretion | what types of hormones are they
gastrin (endocrine hormone) | histamine (paracrine hormone)
62
where is gastrin released from and to
gastrin released from G-cells secreted into blood, (non-localised = endocrine) round body and picked up by gastric pits
63
where is histamine released from and to
released from H-cells (very localised = paracrine) to gastric gland further amplify gastric juice secretion
64
what differs between neural and hormonal signals
neural - rapid but short lived | hormonal - slow but persistent
65
what pH is chyme
2
66
why cant chyme be absorbed
polysaccharide and protein broken into small chains (large SA:V for subsequent digestion), need to be monomers
67
what is secreted into the chyme
``` pepsin intrinsic factor (for later B12 absorption) ```
68
when does the stomach usually emptry
2-4hrs after meal
69
what regulates the rate of stomach emptying
inhibitory signals from small intestine: - enterogastric reflex - secretin - cholecystokinin
70
what is the enterogastric reflex
reflex between stomach and intestines
71
when is secretin released
response to acid
72
when is cholecystokinin released
response to fat