carbohydrate digestion, absorption and blood sugar homeostasis

Question 1

what are the two forms of starch

Answer 1

amylose and amylopectin

Question 2

what are the differences between the two forms of starch

Answer 2

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

Question 3

what enzyme digests the amylose and amylopectin

Answer 3

salivary and pancreatic amylase

Question 4

which bond is broken by the salivary and pancreatic amylase

Answer 4

1,4 bond

Question 5

describe amylose

Answer 5

STRAIGHT linear chain containing 1,4 glycosidic bonding

Question 6

describe amylopectin

Answer 6

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

Question 7

describe cellulose

Answer 7

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

Question 8

describe glycogen

Answer 8

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

Question 9

how is carbohydrates digested in the oral cavity

Answer 9

mechanical and chemical digestion( salivary amylase)

Question 10

how is the carbohydrates digested in the gastro intestinal tract

Answer 10

chemical

Question 11

what is an exocrine gland

Answer 11

a gland that secretes enzymes into a duct

Question 12

what is an endocrine gland

Answer 12

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

Question 13

where does salivary amylase come from

Answer 13

secreted by serous acini of the parotid and submandibular glands

Question 14

what is the optimal ph of salivary amylase

Answer 14

6.7

Question 15

what does salivary amylase break down polysaccharides into

Answer 15

mixture of disaccharides and trisaccharides

Question 16

how long does salivary amylase work for in the stomach

Answer 16

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

Question 17

where is pancreatic amylase secreted from

Answer 17

the pancreatic exocrine acini into the duodenum through the pancreatic duct

Question 18

what is the optimum ph of pancreatic amylase

Answer 18

6.7-7

Question 19

WHAT BOND DOES PANCREATIC AMYLASE DIGEST

Answer 19

1,4 glycosidic bond

Question 20

what does pancreatic amylase break down

Answer 20

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

Question 21

which enzymes are brush border enzymes or disaccharidases

Answer 21

maltase

sucrase and lactase

Question 22

what is the optimal ph of disaccharidases

Answer 22

7-8

Question 23

what do disaccharidases hydrolyse

Answer 23

disaccharides into monosaccharides

Question 24

why do some people suffer from lactose intolerance

Answer 24

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

Question 25

where does carbohydrate absorption occur

Answer 25

occurs in the SI

Question 26

why is the villi folded

Answer 26

to increase surface area

Question 27

what is the most absorbable form of carbs

Answer 27

monosaccharides

Question 28

how do glucose and galactose enter the enterocytes

Answer 28

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

Question 29

how do glucose and galactose leave the enterocyte

Answer 29

via facilitated diffusion and glucose co transported (GLUT2)

Question 30

how does fructose enter the enterocyte

Answer 30

glut5

Question 31

how does fructose leave the enterocyte

Answer 31

leaves via GLUT2 and facilitated diffusion

Question 32

which mode of transport requires energy in the form of ATP

Answer 32

active transport

Question 33

what factors will affect carbohydrate absorption

Answer 33

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

Question 34

what is mineralocorticoid

Answer 34

corticosteroid hormone, which is synthesized by the adrenal cortex.

Question 35

what does aldosterone do

Answer 35

regulation of salt and water in the body

Question 36

how many k calories does glucose produce

Answer 36

3.75K calories of energy/gm

Question 37

what is insulin

Answer 37

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

Question 38

what does insulin do

Answer 38

regulates the level of glucose when glucose levels are high

Question 39

what is glucagon

Answer 39

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

Question 40

what does glucagon do

Answer 40

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

Question 41

what is a homeostatic level of glucose

Answer 41

90mg/100ml

Question 42

what is the structure of insulin

Answer 42

2pp chains A&B linked by disulphide bonds

Question 43

how is insulin synthesised

Answer 43

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

Question 44

what is the molecular weight of insulin

Answer 44

small protein 6000

Question 45

how does insulin work

Answer 45

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

Question 46

what is the co transporter that transports glucose into the cell

Answer 46

GLUT4

Question 47

what are the normal glucose levels when fasting

Answer 47

80-90mg/100ml

Question 48

what are the normal glucose levels when after a meal

Answer 48

120-140/100ml

Question 49

what does intracellular hypoglycaemia lead to

Answer 49

glucogenesis and gluconeogensis

Question 50

what are the symptoms of diabetes

Answer 50

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

Question 51

what are the macrovascular complications of diabetes

Answer 51

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

Question 52

what are microvascular complications of diabetes

Answer 52

``` eye:retinopathy cataract glaucoma kidneys: renal failure nephropathy microalbuminemia ```

Question 53

what are the two hypothesis of vascular damage

Answer 53

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

Question 54

what are dental complications of diabetes

Answer 54

``` xerostomia gum and perio disease loss of teeth impaired and delayed healing infections ```

Question 55

how should we manage diabetic patients

Answer 55

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