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Food + Physiology > RE revise > Flashcards

RE revise Flashcards

1
Q

function of the small intestine

A

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

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2
Q

function of the large intestine

A

storage

water reabsorption

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3
Q

when is the somatic motor act initiated

A

by willed decision to start chewing

becomes automatic

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4
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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5
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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6
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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7
Q

what controls saliva production

A

spontaneous

parasympathetic nerve endings

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8
Q

what is the gastric juice composed of

A 
water
HCl
pepsinogen
intrinsic factor
mucous
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9
Q

what is the HCl for in the gastric juice

A

chemical attack on food

antiseptic

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10
Q

what is the pepsinogen for in the gastric juice

A

pepsin secreted as pepsinogen (inactive precurser)

stomach acid activates pepsin

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11
Q

what is the function of the parietal cells in the gastric gland

A

secrete acid and intrinsic factor (need for vitamin B12 absorption in small intestine) only fundus and body

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12
Q

what is the function of the enteroendocrine cells in the gastric gland

A

secrete hormones into blood

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13
Q

what is the function of the chief cells in the gastric gland

A

secrete protein pepsinogen

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14
Q

what regulates the rate of stomach emptying

A

inhibitory signals from small intestine:

  • enterogastric reflex
  • secretin
  • cholecystokinin
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15
Q

what is the enterogastric reflex

A

reflex between stomach and intestines

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16
Q

what prevents chyme moving from stomach to the duodenum

A

pylorus sphincter

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17
Q

exocrine pancreas function

A

provides main digestive fluid of small intestine

empties into duodenum via pancreatic duct/common bile duct

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18
Q

what does the pancreatic secretion consist of

A

water
bicarbonate
enzymes

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19
Q

what are the enzymes in the pancreatic secretion

A 
trypsin(OGEN)
chymotrypsin(OGEN)
amylase
lipase
nuclease
STORED INACTIVE - ZYMOGENS
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20
Q

when are the enzymes from the pancreatic secretion activated

A

when reach duodenum

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21
Q

what is involved in the neurological control of the pancreas

A

parasympathetic nerves

  • acetylcholine
  • vasoactive intestinal peptide
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22
Q

an example of bile - excretory

A

breakdown products of metabolism
e.g. haemoglobin, break down products are bile pigments
biliverdin (green)
bilirubin (red)
they’re converted to stercobilin (brown) (also use bacteria)

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23
Q

what does the enzyme disaccharidases do

A

completes carbohydrate digestion

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24
Q

what does the enzyme aminopeptidases do

A

complete protein digestion

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25
Q

how does the small intestine contribute to digestion

A

absorption of nutrients into blood stream

during peristalsis longitudinal and circular muscles in SI wall contract to push food down tract

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26
Q

how are enterocytes replaced

A

constantly replaced by differentiation of simple cells from crypts of LieberKuhn (glands at villus base)

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27
Q

what is the motor activity of intestines effect

A

propulsive movement - shifts material along gut (peristalsis)
mixing movements - mixes digesta with secretions ensures material close to absorptive surface

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28
Q

what occurs during peristalsis in the motor activity of intestine

A

motor program coordinated by enteric nerves
stimulus causes circular muscle infront of digesta (anal side) to relax due to inhibitory neurone activation
contraction of circular muscle behind it (oral side) ue to excitatory neurone activation
process continues till digesta doesn’t provide sufficient stretch

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29
Q

what occurs during segmentation in the motor activity of intestine

A

motor program coordinated by enteric nerves
initiated by mild stretching of intestine
circular muscle contraction at regular intervals these alternate with periods of relaxation in adjacent intestine sections, break up gut contents, throughly mixing - crucial for efficient absorption

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30
Q

what is the cecum

A

pouch below small/large intestine junction

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31
Q

what causes a longer shelf life on cooked foods

A

smoke presence
lower water activity
decreased microbial load

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32
Q

what is the effect on collagen when cooked

A

triple helix structure unwinds

form gelatin which is water soluble and nutritious

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33
Q

what is the effect on fat when cooked

A

fat soluble vitamins dissolved in oil droplets in food
protects vitamins from oxidation
assits gut uptake

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34
Q

what is the effect on starch when cooked

A

gelatinises starch, easier to break amylase in the gut, increasing sugar supply

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35
Q

what nutrients does the sweet receptor sense

A

sugars as carbohydrate measure

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36
Q

what nutrients does the umami receptor sense

how is it activated

A

glutamic and aspartic acids activate receptor

measure of protein

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37
Q

what nutrients does the fat receptor sense

how is it activated

A

activated by free fatty acids

measure of oils/fats containing triglycerides and phospholipids

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38
Q

what is the olfactory bulb gustatory cortex

A

primary odor, taste signal centres

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39
Q

what is the fronto-orbital cortex function

A

integrates all signals
develops ‘liking’ principle
food liked, more eaten
mouth-brain axis

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40
Q

where are taste and smell receptors located

A

around the body

especially gut

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41
Q

how is a nutrient detected

A

gut-brain axis
receptor and hormone signals sent to brain
sub-conscious message measures relative level of protein, carbohydrate, fat
indicates nutritional status of body
taste receptors in gut control first process of digestion
e.g. sweet - molecule hits receptor in gut, connected to cells that make enzymes for sugar digestion

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42
Q

what is the gut-brain-mouth-axis

A

brain uses nutritional status to modify sensitivity of taste signals in brain
e.g. if food has protein but no carbohydrate craving sweet can occur

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43
Q

how can hormone production be continually modified by external events

A

interconnections between nervous and endocrine systems

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44
Q

what do the gut hormones do

A 
control:
passage of food material
appetite
regulate digestive and absorptive processes
regulate blood sugar levels
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45
Q

where is ghrelin produced

A

mainly stomach

also small intestine, pancreas, brain

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46
Q

what does ghrelin cause

A

stimulates appetite

promotes fat storage

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47
Q

what stops ghrelin secretion

A

stretching of stomach

carbohydrates and proteins

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48
Q

where is gastrin produced

A

G cells in stomach lining

upper small intestine

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49
Q

when is gastrin released

A

in anticipation of eating
stretching of stomach wall
proteins in stomach
increased pH

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50
Q

what does gastrin cause

A

during meal stimulates stomach to release gastric acid - break down proteins, absorb vitamins, kill bacteria
stimulates gallbladder to empty bile
stimulate pancreas to secrete enzymes
increases muscle contractions

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51
Q

what stops gastrin secretion

A

lower pH - negative feedback

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52
Q

where is glucagon produced

A

secreted from L-cells in small intestine and pancreas

53
Q

what causes glucagon secretion

A

biphasic manner

  • about 10 mins after meal triggered by neural signal
  • digestion starts, trigger second release, stays several hours
54
Q

what does glucagon cause

A

stimulate release of insulin from pancreas (delays glucagon release)
increases feeling of fullness during and between meals via centres in brain
slows stomach emptying - decreases food and water intake

55
Q

where is cholecystokinin produced

A

I-cells in duodenum lining

56
Q

when is cholecystokinin secreted

A

after a meal

in response to fatty acids and amino acids in stomach

57
Q

what does cholecystokinin cause

A

slows emptying of food from stomach
stimulates bile production and release
increases release of fluid and enzymes from pancreas t break fats, proteins, carbohydrates
increases fullness feeling during meal

58
Q

when do cholecystokinin levels increase

A

15 minutes after meal began for 3hrs

59
Q

where is pancreatic peptide YY secreted

A

L-cells in small intestine

60
Q

when is pancreatic peptide YY secreted

A

stimulated by food presence in digestive tract (particularly fat and protein) bile and CCK

61
Q

what does pancreatic peptide cause

A

decreases appetite
slows food passing along gut - increase nutrient absorption and digestion efficiency
increases water and electrolyte absorption from colon

62
Q

what does leptin do

A

regulate energy homeostasis, neuroendocrine function and metabolism in energy excess and energy deficiency
regulate food intake by inhibiting hunger

63
Q

what occurs in the initial phase

A 
tactile receptors in the lips, face, tongue and hands detect:
- differences in force
- particle size
- chemical stimulus
- heat stimulus
during hand and mouth touch
nerve fibres in the:
- muscle
- joints
- tendons
sense muscle tension/relaxation - perception of e.g. heaviness
64
Q

what are the mechanoreceptor processes during mastication

A
  • muscle feedback on rate and strength of chewing

- feedback on how well particles mix with saliva to form bolus

65
Q

what are the somatosensory receptors

A 
mechanoreceptors
chemoreceptors 
thermoreceptors
nociceptors
proprioceptors
66
Q

what does the retina do

A

convert light energy to neural impulses

transmitted to brain via optic nerve

67
Q

how do we smell the food

A

volatile molecules transported in air to nose
sensed by millions of cilia (smell receptors) covering olfactory epithelium
olfactory bulb sends signals from receptors to brain

68
Q

what are the two routes volatiles reach the cilia

A

ortho nasally - sniffing

retro nasally - during eating, food condensed whilst chewing pushed back out through nasal tract to receive aroma

69
Q

why is saliva able to spread on oral surfaces but not easily washed off

A

saliva is non-newtownian

70
Q

what occurs to food structure during reconstruction phase

A

interaction with body mucins
microstructure change due to enzyme action
re-assembly of structure as digestion function

71
Q

what is the intestinal phase

A

simulated intestinal fluid, bile salts added, other enzymes to simulate what happens in duodenum

72
Q

what is homogeneity

A

fat droplets everywhere in stomach

73
Q

what is heterogeneity

A

water layer at bottom of stomach, not many nutrients
oil layer on top where all nutrients are - high caloric load
(water phase empties first)

74
Q

what happens when the mucosal mast cells are activated

A

triggers release of inflammatory mediators

  • transepithelial fluid loss
  • smooth muscle contraction
  • vomiting and diarrhoea
  • anaphylaxis
75
Q

what is the lamina propria

A

close network of loose connected tissues in the villi

76
Q

how does the intestine prevent invasion

A

epithelium with thick overlying mucus form barrier against microbial invasion

77
Q

what is the peyer patches - M cell function and process

A

sampling antigens in lumen then transport to antigen-presenting cell on the basolateral side via transcytosis

78
Q

what do dendritic cells do

A

extend dendrites between epithelial cells to sample antigens that are then broken and presented to lymphocytes
usually causes an anti-inflammatory response

79
Q

what happens to fight against parasites

A

attracted to parasite
release large amount WBC to destroy it
antibodies recognise some characteristics of cells and bind, label cells for destruction
cells e.g. mast, recognise the antibodies
release mediators
destroy invader

80
Q

when does IgE mediated hypersensitivity occur

A

antigen makes contact, taken up and processed by antigen-presenting cells
if allergic also presents co-stimulatory molecules on surface to Thelper cells
T cells make IgE antibodies specific to allergen
T helper cell makes cytokines
stimulate B cells to multiply and differentiate IgE-plasma producing cells
IgE attach via constant regions to mast cell receptors
mast cells have granules packed with chemicals that cause hypersensitivity response

81
Q

how are inflammatory molecules released

A

epithelium contact with bacteria
activates immune cells
release inflammatory molecules

82
Q

what is diet induced thermogenesis

A

body requires energy to digest food

83
Q

how is the energy kept balanced

A

series of interconnected loops some electrical most chemical
body releases signals turn on/off other signals through endocrine system
use hormones

84
Q

what does the endocrine system regulate

A

appetite and energy

85
Q

enforcement cycle - obese

A

brain reward system: hedonic overrides homeostatic behaviour
reward system: responds to stimulus of especially palatable food - lots of pleasure and motivation generated
homeostatic control in hypothalamus and brain stem:
still hunger
no satiation as resistance to the leptin and insulin

86
Q

what information does an x-ray have when comes out other side

A

comes out other side
carries spatial absorption information on tissues and structures
converts this into light for film or digital capture

87
Q

what are the negatives of using radiographic x-ray technology

A

ionizing radiation can break chemical bonds in tissue = biological damage
many foods and beverages must be mixed with radiopaque material

88
Q

why is MRI so useful

A

can be tuned to highlight many different characteristics of food, chime, tissue such as water density

89
Q

how is gastric emptying measured

A

measure serial image stacks across abdomen at intervals
volume of meal (+/- gas) measured at each time point by drawing round boundaries of stomach and summing across all slices

90
Q

what occurs in the small bowel

A

bolus transport - propulsive

mixing/digestion - segmental

91
Q

what is colonic gas

A

poorly digested carbohydrates

thought to ferment in the colon and be the cause of some peoples bloating

92
Q

how does the colon move chyme along

A

intervals approximately every 2-hrs

colon undergoes high amplitude propagating contractions (HAPCs)

93
Q

what does the cerebellum do

A

integrating sensory perception

process brain responses - emotional regulation, cognitive and sensory perception - visual memory sound

94
Q

what happens when taste is detected

A

detected on taste buds
signals transmitted through taste fibres to brain stem
protected to thalamus
projected then to primary taste cortex

95
Q

what is the thalamus

A

gateway to primary sensory areas

ALL EXCEPT OLFACTORY pass through thalamus

96
Q

what occurs at the hypothalamus

A

metabolism integration - control appetite
receive neural and hormonal inputs from peripheral and central signalling
lots of communication between gut, stomach, brain - when to eat/stop

97
Q

what does fMRI do

A

relies on oxygenated and deoxygenated blood as they have different levels of magnetic properties
can be detected by MRI scanner

98
Q

what does the kidney maintain within the body

A

maintains:

  • water balance in body
  • plasma volume (blood pressure)
  • acid-base balance (pH)
  • osmolarity (solute concentration)
99
Q

what are the efferent arterioles divided into

A

peritubular capillaries

100
Q

what is the tube in the tubular component made up of

A

hollow tube formed from single layer epithelial cells

101
Q

what is the distal tubule

A

highly coiled

lies in cortex and empties into collecting duct

102
Q

how does colloid osmotic pressure form

A

in plasma contains proteins, if these are not passed into the filtrate - their concentrated in the unfiltered plasma increases = exert resistance to further filtration of fluid

103
Q

what must a substance do to be reabsorbed

A
  • cross luminal membrane of tubular cell
  • pass through tubular cell cytosol
  • cross tubular cell basolateral membrane to enter interstitial fluid
  • diffuse through interstitial fluid
  • penetrate capillary wall to enter blood plasma
104
Q

what happens for water channels to be inserted in DCT and CD

A

vasopressin binds to the receptor on the DCT basolateral membrane
once activated, receptor cyclises ATP to cyclic AMP - causes water channels to be inserted

105
Q

what happens in the renin-angiotensisn-aldosterone system when e.g. atrial blood pressure drops/ ECF drops/ decrease in NaCl

A

kidney detects change and releases renin
renin cleaves apart angiotensinogen = angiotensin I
pass through lungs where angiotensin-converting enzyme cleaves more of angiotensin I = angiotensin II (active hormone)
angiotensin II pass to adrenal cortex = release of aldosterone
aldosterone causes increase in sodium reabsorption in kidney tubule
angiotensin II then helps correct

106
Q

what are the properties required to be classed as a probiotic

A
  • beneficial effect on host
  • nonpathogenic and non-toxic
  • contain large number of viable cells
  • capable of surviving and metabolising in the gut
  • remain viable during storage and use
  • good sensory properties
  • be isolated from same species as host
107
Q

what are the abilities needed for a probiotic

A
  • beneficial effects
  • resistance to bile, hydrochloric acid and pancreatic juice
  • GI tract colonisation
  • adhere to epithelial cells
  • antimicrobial activity
  • anticarcinogenic activity
  • immune modulation/stimulation
  • reduce intestinal permeability
108
Q

what is the function of the intestinal barrier

A

tolerance against commensals and immunity against pathogens require intact mechanisms for antigen uptake, recognition, processing and response

109
Q

what are some mechanisms of probiotic activity

A
  • antimicrobial
  • improve environment for beneficial bacteria growth
  • make beneficial end product
  • reduce harmful end products
  • stimulate immune system against pathogens
110
Q

what classification properties must a prebiotic have

A
  • not hydrolysed or absorbed in upper part GI tract
  • selective substrate for one or a limited number of potentially beneficial commensal bacteria in colon, stimulating bacteria to grow, become metabolically activated, or both
  • alter colonic microflora towards healthier composition
  • fermented by intestinal microflora
111
Q

what is the end product of heterofermenters

A

lactic acid
acetic acid
CO2
ethanol

112
Q

carbohydrate metabolism problem

A

portion of ingested carbohydrate not all digested in small intestine
principally starch, cellulose, hemicellulose

113
Q

what happens during carbohydrate metabolism

A

complementary biochemical reactions carried out by different GMFs:
polysaccharide - oligosaccharide - intermediate product
then:
- liberation of short chain fatty acids - capable of absorption by large intestine
- CO2, H2, SO4 formed

114
Q

what do CO2, H2, SO4 produce in carbohydrate metabolism

A

they form CH4, H2S and acetate

acetate reused in metabolism as it is a SCFA

115
Q

what parts of immune system need to be in balance

what happens if not balanced

A

Th1 and Th2 cells

  • too much Th1 activity = excessive tissue inflammation
  • too much Th2 activity = onset of allergy/autoimmune (AI) disorders
116
Q

what are the observed changes in test when mice were without GMF

A 
nervous system fail to develop
abnormal neurotransmission
behavioural changes - stress
intestinal transit become slow
memory problems
117
Q

what happens in body when we eat raw egg

A

contains conalbumin which binds to iron

and avidin which binds to biotin

118
Q

what does protease do in mammals

A

trypsin is a protease

in the duodenum trypsin catalyses peptide bond hydrolysis, break down proteins to smaller peptides

119
Q

what occurs in convulsive ergot poisoning

A 
twisting and contorting body in paint 
trembling
shaking muscle spasms
confusion
delusions
120
Q

what occurs in gangrenous ergot poisoning

A

decreased blood flow
infections in extremities
loss extremities
burning pain

121
Q

what does this cyanogen ingestion cause

A

health problems
acute intoxication
goitre
cretinism due to lack of iodine

122
Q

what do glucosinolates cause

A

bitterness in cauliflower and sprouts

some may inhibit some cancer

123
Q

what does phytic acid do

A

store phosphorus as phytic acid

124
Q

what effects does oxalic acid have

A 
abdominal pain
kidney problem 
low blood pressure 
throat pain
tremors
125
Q

what does solanine cause

A

gastrointestinal and neurological disorders

126
Q

what do non protein amino acids cause

A

general stiffness and weakness of skeletal muscles

127
Q

what are tannins

A

often astringent

bitter plant polyphenolic compounds

128
Q

what may flavonoids, phenols and tannins cause

A

chelate metals, reduce their absorption
inhibit digestive enzymes
bind to proteins, amino acids and cause their precipitation

Food + Physiology (17 decks)

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