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GI lectures > post absorptive mechanisms & energy balance > Flashcards

post absorptive mechanisms & energy balance Flashcards

1
Q

why are amino acids, triglyceride & glucose transported to the liver

A

for conversion into storage molecules

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2
Q

where are fats stored

A

adipose tissue

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3
Q

where is glycogen stored

A

muscle

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4
Q

where are proteins stored

A

proteins are not stored
they are converted to fats
and used as energy supplies

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5
Q

BMI calculation

A

Weight (Kg)/ Height2 (m)

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6
Q

what BMI is obese

A

above 30

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7
Q

what BMI is normal

A

between 18.5 and 25

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8
Q

what BMI is overweight

A

between 25 and 30

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9
Q

what BMI is underweight

A

below 25

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10
Q

how long are glycogen stores sufficient for an adult male

A

roughly 12 hoursn

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11
Q

how long are lipid stores sufficient for

A

3 months

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12
Q

when does tissue protein as a source of energy supply become significant

A

only in times of prolonged starvation

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13
Q

energy requirement of brain and liver

A

the brain & liver represent about 4.6% of body weight yet consume around 40% of energy
requirement at rest

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14
Q

which fuels does brain use

A

glucose
ketone bodies

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15
Q

which fuels do muscle use

A

glucose
ketone bodies (in starvation), triacyglycerol
branched-chain amino acids

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16
Q

which fuels does liver use

A

amino acids, fatty acids (including short chain acids), glucose & alcohol

ketone bodies are not used by the liver, although they are produced here
they are then sent to extrahepatic tissue to buy used there, the liver cannot use ketone bodies for fuel due to the fact they do not have the enzyme thiolase

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17
Q

which fuels does kidney use

A

glucose & ketone bodies (cortex)

only glucose (medulla)

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18
Q

which fuels does small intestine use

A

ketone bodies (mainly in starvation), glutamine (amino acid)

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19
Q

which fuels does large intestine use

A

short-chain fatty acids, glutamine

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20
Q

what is basal metabolic rate

A

minimum amount of energy required to keep the body alive

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21
Q

how is BMR measured

A

by O2 consumption in a person who is awake, restful and faster
for 12 hours

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22
Q

impact of age on BMR

A

BMR decrease with age

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23
Q

units of BMR

A

kcal expended/hr/m2

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24
Q

functions of vitamin A (7)

A
  • Cellular growth & differentiation
  • Process of vision (retinal pigments)
  • Healthy skin
  • Reproduction
  • Embryonic development
  • Maintenance of bodies mucus membranes
  • Used in lymphocyte production - immune system
25
Q

sources of vitamin A

A
  • Liver
  • Dairy products
  • Oily fish
  • Margarine
26
Q

what does vitamin A deficiency cause

A
  • night blindness
  • Xerophthalmia (eye fails to produce tears)
  • Growth retardation
  • Keratinisation of epithelia
  • Impaired hearing, taste & smell
  • Increased susceptibility to infection
27
Q

functions of vitamin C

A
  • Synthesis of; collagen, neurotransmitters & carnitine (used in beta-oxidation)
  • Antioxidant ability - can donate electrons to radical O2 compounds
  • Absorption of non-haem (plant based) iron
28
Q

sources of vitamin C

A
  • Citrus fruits
  • Green leafy vegetables
  • Potatoes
  • Kidney
29
Q

what does vitamin C deficiency cause

A

Initial signs are non-specific
* Weakness
* Bleeding gums
* Hyperkeratosis (thickening of outer layer of skin)
* 50 - 100 days without Vitamin C = signs of scurvy

30
Q

function of B vitamins

A

important in cell metabolism & energy production

31
Q

where is the main B vitamin found

A

vitamin B 12

found in fish, poultry, meat & eggs

32
Q

what does B12 deficiency cause

A

results in less erythrocyte formation - pernicious anaemia

33
Q

where is B12 absorbed

A

in the terminal ileum

intrinsic factor is required which is produced by the parietal cells of
the stomach

34
Q

what does the term vitamin D refer to

A

denotes a group of closely related compounds
- Liver storage prevent deficiency for 3-4 months

35
Q

what forms vitamin D3

A

(cholecalciferol) is formed by the action of ultra-violet (UV) radiation
from sunlight on a cholesterol derivative in the skin

36
Q

how is vitamin D metabolised

A

by the addition of hydroxyl groups, first in the liver and then in
certain kidney cells, the end result of these changes is 1,25-dihydroxyvitamin D
(1,25-(OH)2D) - the active hormonal form of vitamin D

37
Q

where is vitamin D2 derived from

A

plants

38
Q

function of the active hormonal form of vitamin D

A

to stimulate intestinal absorption of Ca 2+ and phosphate

39
Q

consequence of vitamin D deficiency

A

decreased intestinal Ca2+ absorption resulting in a
decreased plasma Ca2+
* This decrease in detected via a plasma membrane Ca2+ receptor in the
parathyroid glands (embedded in the posterior surface of the thyroid gland)
* Resulting in the parathyroid glands releasing PARATHYROID HORMONE (PTH)
which exerts multiple actions that increase extracellular Ca2+ concentration

40
Q

main function of vitamin E

A

as an antioxidant

41
Q

main function of vitamin K

A

is essential for the production of clotting factors (10,9,7 & 2) in the liver

42
Q

what is malabsorption

A

The inadequate absorption of nutrients from the intestines

  • Failure to absorb certain vitamins, minerals, carbohydrate, proteins or fats
43
Q

what is giardiasis

A

infection which causes the villi to atrophy thus reducing absorption
capacity

44
Q

what is celiac disease

A

an auto-immune condition whereby gluten is partially degraded triggering an immune response whereby the system attacks the villi & microvilli resulting in a loss of intestinal brush border surface area resulting in decreased absorption of
many nutrients
-
Can prevent the absorption of vitamin D which ultimately results in the decrease in calcium absorption in the GI tract - resulting is osteoporosis

45
Q

which is the only anabolic hormone that controls metabolism

A

insulin

the rest are catabolic

46
Q

what determines weight

A

a balance of energy intake and expenditure

influenced by genetics, environment and energy regulation

47
Q

where is the appetite control centre

A

hypothalamus

Within in hypothalamus lies the arcuate nucleus, which plays a key role in the control of appetite.

48
Q

what do primary neurones in the appetite centre do

A

process external signals, be it neuronal, hormonal or nutritional.

are either excitatory or inhibitory.

49
Q

what do secondary neurones in the appetite centre do

A

responsible for co-ordinating the inputs received via the primary neurone.

50
Q

what do excitatory neurotransmiiters do

A

promote hunger

51
Q

what do inhibitory neurotransmitters do

A

supress hunger

52
Q

what is ghrelin

A

a peptide hormone produced in the pancreas and released from the stomach wall when the stomach is empty.

it stimulates the excitatory primary neurones, and therefore stimulates appetite.

when the stomach is full, ghrelin release is inhibited, thus the appetite stimulus is also inhibited.

53
Q

what is PYY

A

a short peptide hormone released by cells in the ileum and colon in response to feeding.

It inhibits the excitatory primary neurones of the arcuate nucleus.

This causes appetite suppression.

54
Q

what is leptin

A

a peptide hormone released into the blood by adipocytes (fat cells).

Leptin stimulates the inhibitory neurones and inhibits the excitatory neurones in the arcuate nucleus to cause suppression of appetite.

55
Q

what is insulin

A

a hormone released from beta cells in the islets of Langerhans of the pancreas.

This suppresses appetite in a similar way to leptin.

56
Q

factors influencing BMR

A
  • genetics
  • gender
  • age
  • body SA
  • weight
  • body fat %
  • diet
    -body temperature
  • external temperature
    -excercise
57
Q

factors that increase BMR

A

Being overweight, Fever, being male, pregnancy, caffeine, hyperthyroidism, exercise, low temperature

58
Q

factors that decrease BMR

A

Increase in Age, being female, malnutrition/starvation, hypothyroidism

GI lectures (9 decks)

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