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IBMS SR > carbohydrate digestion, absorption and blood sugar homeostasis > Flashcards

carbohydrate digestion, absorption and blood sugar homeostasis Flashcards

1
Q

what are the two forms of starch

A

amylose and amylopectin

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2
Q

what are the differences between the two forms of starch

A

branched in amylopectin due to the 1,6 glycosidic bond whereas amylose only has 1,4

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3
Q

what enzyme digests the amylose and amylopectin

A

salivary and pancreatic amylase

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4
Q

which bond is broken by the salivary and pancreatic amylase

A

1,4 bond

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5
Q

describe amylose

A

STRAIGHT linear chain containing 1,4 glycosidic bonding

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6
Q

describe amylopectin

A

branched structure of alpha glucose and contains 1,4 and 1,6 glycosidic bonding

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7
Q

describe cellulose

A

a polysaccharide which is made out of b glucose monomers joined together by b1,4 glycosidic bonding. it is largely indigestible in the SI and therefore excreted

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8
Q

describe glycogen

A

polysaccharide of a glucose which is bonded by 1,4 and 1,6 glycosidic bonding. highly branched structure

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9
Q

how is carbohydrates digested in the oral cavity

A

mechanical and chemical digestion( salivary amylase)

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10
Q

how is the carbohydrates digested in the gastro intestinal tract

A

chemical

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11
Q

what is an exocrine gland

A

a gland that secretes enzymes into a duct

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12
Q

what is an endocrine gland

A

secretes its hormones into the blood stream to get to the site of action

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13
Q

where does salivary amylase come from

A

secreted by serous acini of the parotid and submandibular glands

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14
Q

what is the optimal ph of salivary amylase

A

6.7

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15
Q

what does salivary amylase break down polysaccharides into

A

mixture of disaccharides and trisaccharides

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16
Q

how long does salivary amylase work for in the stomach

A

for 1-2 hours before being deactivated by the gastric acids

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17
Q

where is pancreatic amylase secreted from

A

the pancreatic exocrine acini into the duodenum through the pancreatic duct

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18
Q

what is the optimum ph of pancreatic amylase

A

6.7-7

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19
Q

WHAT BOND DOES PANCREATIC AMYLASE DIGEST

A

1,4 glycosidic bond

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20
Q

what does pancreatic amylase break down

A

more complex carbohydrates that take longer to break down to disaccharides or oligosaccharides

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21
Q

which enzymes are brush border enzymes or disaccharidases

A

maltase

sucrase and lactase

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22
Q

what is the optimal ph of disaccharidases

A

7-8

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23
Q

what do disaccharidases hydrolyse

A

disaccharides into monosaccharides

24
Q

why do some people suffer from lactose intolerance

A

due to a lack of the lactase enzyme therefore lactose cannot be broken down and the water potential in the gut in reduced therefore water moves out via osmosis and the patient suffers from diarrhoea

25
Q

where does carbohydrate absorption occur

A

occurs in the SI

26
Q

why is the villi folded

A

to increase surface area

27
Q

what is the most absorbable form of carbs

A

monosaccharides

28
Q

how do glucose and galactose enter the enterocytes

A

via active transport using the sodium dependant co transport (SGLT1)

29
Q

how do glucose and galactose leave the enterocyte

A

via facilitated diffusion and glucose co transported (GLUT2)

30
Q

how does fructose enter the enterocyte

A

glut5

31
Q

how does fructose leave the enterocyte

A

leaves via GLUT2 and facilitated diffusion

32
Q

which mode of transport requires energy in the form of ATP

A

active transport

33
Q

what factors will affect carbohydrate absorption

A

faster through intact mucosa- can be damaged due to lactose intolerance cus of inflammation
thyroid hormones increase the absorption
mineralocorticoid eg aldosterone
Na+ conc- higher the conc the more absorption

34
Q

what is mineralocorticoid

A

corticosteroid hormone, which is synthesized by the adrenal cortex.

35
Q

what does aldosterone do

A

regulation of salt and water in the body

36
Q

how many k calories does glucose produce

A

3.75K calories of energy/gm

37
Q

what is insulin

A

a hormone secreted by b cells in the islets of langerhans in the pancreas

38
Q

what does insulin do

A

regulates the level of glucose when glucose levels are high

39
Q

what is glucagon

A

it is a hormone secreted by a cells in the islets of langerhans in the pancreas

40
Q

what does glucagon do

A

it is stored in the liver to glucose and released when blood glucose is low

41
Q

what is a homeostatic level of glucose

A

90mg/100ml

42
Q

what is the structure of insulin

A

2pp chains A&B linked by disulphide bonds

43
Q

how is insulin synthesised

A
  1. proinsulin with 1 pp chain enters through ER
  2. ER adds 2 chains so there’s 3 PP chains A-C-B
  3. packaged at the golgi and the c structure is cut by endopeptidases and TGN releasing insulin
44
Q

what is the molecular weight of insulin

A

small protein 6000

45
Q

how does insulin work

A
  1. insulin attaches to the insulin receptors on cell membrane, stimulating GLUT-4
  2. causes GLUT-4 receptor to bind to the membrane and glucose enters the cell through GLUT-4
  3. glucose is converted into pyruvate and fatty acids stored in adipose tissue
46
Q

what is the co transporter that transports glucose into the cell

A

GLUT4

47
Q

what are the normal glucose levels when fasting

A

80-90mg/100ml

48
Q

what are the normal glucose levels when after a meal

A

120-140/100ml

49
Q

what does intracellular hypoglycaemia lead to

A

glucogenesis and gluconeogensis

50
Q

what are the symptoms of diabetes

A 
fatigue 
blurred vision 
slow healing sores
unusual weight loss 
yeast infections 
polyuria 
itching in groin and vagina 
nausea 
xerostomia
51
Q

what are the macrovascular complications of diabetes

A 
brain: 
stroke 
TIA 
cognitive impairment 
heart: 
coronary syndrome 
MI 
congestive heart failure 
extremities:
diabetic foot 
skin ulcers 
amputation
52
Q

what are microvascular complications of diabetes

A 
eye:retinopathy
cataract
glaucoma 
kidneys:
renal failure 
nephropathy 
microalbuminemia
53
Q

what are the two hypothesis of vascular damage

A

damage to the blood vessel due to high glucose level causing oxidative stress in the lining affecting mitochondria
or glycated products and the glucose glycates fsatty acids which build up on the vessels

54
Q

what are dental complications of diabetes

A 
xerostomia 
gum and perio disease 
loss of teeth 
impaired and delayed healing 
infections
55
Q

how should we manage diabetic patients

A 
regular visits 
maintenance of OH 
regular checks 
antibiotic coverage 
controlled blood sugar 
mouth wash 
artificial saliva

IBMS SR (38 decks)

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