lab 9: glucose metabolism 'from mouth to muscle'

what happens in the lab

hands-on experimentation with plasma glucose testing under conditions of rest, pre-activity, and post activity consumption

in what form is glucose stored

glycogen

where is glycogen stored

the liver and skeletal muscle

why is homeostatic maintenance of plasma glucose important

because the brain is almost entirely dependent on glucose as an energy substrate

how is glucose homeostasis maintained

begins with feedforward reflexes following ingestion and digestion by the gastrointestional tract

once in the plasma, glucose is regulated by the antagonistic control of the pancreatic hormones insulin and glucagon

when is insulin released

when the blood sugar gets too high, insulin is released from the pancreas

what happens when insulin is released

insulin stimulates cells, particularly muscle, fat, and liver cells to uptake glucose from the bloodstream, promoting the storage of glucose as glycogen in the liver and muscle cells (glycogenesis) and helps to convert glucose into fat in adipose tissues

this acts to lower blood glucose levels

what happens when glucagon is released

glucagon stimulates the liver to break down glycogen into glucose through glycogenolysis and release it into the bloodstream and forms more glucose from non-carb sources such as amino acids through gluconeogenesis

this causes decreased uptake of glucose by both the muscles and adipose tissues

this acts to increase blood glucose levels

when is glucagon released

when blood glucose levels are low

glycogenolysis

the process of breaking down glycogen into glucose

is glucose stored or released in the liver

when insulin is released (fed state), the liver stores glucose as glycogen (glycogenesis)

when glucagon is released (fasted state), the liver releases glucose into the blood by breaking down glycogen (glycogenolysis) or making new glucose (gluconeogenesis)

prior activity group

test baseline (fasting value)

exercise for 15 mins then test plasma glucose

drink 300 mL glucose solution

sits and tests glucose at 30, 45, and 60

inactive group

test baseline (fasting value)

drink 300 mL glucose solution

sit and test glucose at 15, 30, 45, 60

post activity group

test baseline (fasting value)

drinks 300 mL glucose solution

exercise for 15 mins and test plasma glucose

sits and tests glucose at 30, 45, and 60

what does the magnitude of the AUC for each 15 min interval tell you

the magnitude of the AUC is an indicator of overall increase in plasma glucose

formula for AUC

1/2([glucose]a + [glucose]b) * (time point b - time point a)

axes for AUC graph

x = time (min)

y = [glucose] (mg/dL)

minimum time volunteers had to fast

3 hours of anything except water

why no diet drinks during fasting

the sweet taste will interfere with the tests, whether or not the body absorbs the calories

lancing device

one-time, one-person use only do not reuse

what to do the first time you use a new test drum

run a control test to ensure that the meter and test strips are functioning properly

function of a control solution

it is a liquid with known glucose concentration, used to stimulate a blood sample and ensure that the meter reads a concentration correctly

how to get a good drop of blood for the glucometer

1. wash hands in warm soapy water and ensure completely dry (warmth of water helps to stimulate blood flow)

2. hang arm at side for 30 seconds to allow blood to flow to the fingertips

3. grasp the finger near area to be pricked and squeeze for 3 secs

4. keep the hand down, prick side of fingertip and squeeze gently to get a drop of blood

5. apply drop of blood to test strip immediately

glucometer

device for measuring plasma glucose concentrations from a drop of blood obtained by a lancet

where to dispose fo anything that contacts blood BESIDES SHARPS

in the biowaste bag

all sharps go into the sharps container

mouth enzymes/digestive aids

salivary amylase

mouth substrates/products

starch --> maltose

mouth absorption

none

stomach enzymes/digestive aids

none specific

stomach substrates/products

none

stomach absorption

none

small intestine enzymes/digestive aids

Pancreatic Amylase

Maltose

Lactose

Bicarbonate

Sucrose

Bile Sucrase

GI Hormones

PAM, LBS, BSGIH

pam, lbs, bull shit girl i heard

small intestine substrates/products

disaccharides --> monosaccharides

small intestine absorbtion

GLUT 5 for fructose

how is glucose transported from the plasma into most cells

by the GLUT 2&4 transporters

what is the rational for using GLUT 2 and 4 transporters for glucose movement into cells

glucose is unable to cross the membrane on its own and therefore needs a transporter

which gastrointestinal hormone is upregulated be presence of glucose in the small intestine

GIP

GIP function

stimulates insulin release

which metabolic hormone is upregulated in the presence of the GIP hormone

insulin

insulin stimuli for release

increase in plasma glucose

insulin receptor/integrating center

beta cells of the pancreas

insulin efferent

increased insulin release

insulin effectors

liver, muscle, and adipose cells

insulin immediate response

increase in gluconeogenesis (other --> glucose)

increase in glycogenesis (glucose --> glycogen)

increase in lipogenesis

increase in protein synthesis

insulin overall response

decrease in plasma glucose

glucagon stimuli for release

decrease in blood glucose, increase in amino acids

glucagon receptor/integrating center

alpha cells of pancreas

glucagon efferent

glucagon release

glucagon effectors

liver

glucagon immediate response

increase in gluconeogenesis

increase in glycogenolysis

increase in ketone production

glucagon overall response

increase in plasma glucose

in what organs and in what form is glucose stored

as glycogen, in the muscles, liver, and kidney

during inactivity, following glucose ingestion, what 3 processes happen

1. glucose becomes stored in the liver and muscles (glycogenesis)

2. glucose becomes stored in adipose tissues as fat (lipogenesis)

3. glucose goes to the brain for function

during prior activity, following glucose ingestion, what 3 processes happen

1. liver releases glycogen and makes glucose from it (glycogenolysis)

2. small intestine releases amino acids and forms glucose from it (gluconeogenesis)

3. glucose is used to power the brain

during post activity, following glucose ingestion, what 3 processes happen

1. liver and muscle cells uptake glucose and stores it as glycogen (glycogenesis)

2. small intestine releases amino acids to form glucose (gluconeogenesis)

3. glucose goes to power the brain

effect of inactivity on:

glucose absorption, insulin secretion, glucagon secretion, liver glycogenolysis, and muscle glycogenolysis

glucose absorption: decrease

insulin secretion: increase

glucagon secretion: decrease

liver glycogenolysis: increase

muscle glycogenolysis: increase

effect of prior activity on:

glucose absorption, insulin secretion, glucagon secretion, liver glycogenolysis, and muscle glycogenolysis

glucose absorption: increase

insulin secretion: decrease

glucagon secretion: increase

liver glycogenolysis: increase

muscle glycogenolysis: increase

effect of post activity on:

glucose absorption, insulin secretion, glucagon secretion, liver glycogenolysis, and muscle glycogenolysis

glucose absorption: decrease

insulin secretion: increase

glucagon secretion: decrease

liver glycogenolysis: decrease

muscle glycogenolysis: increase

dietary advice to eat complex carbohydrates rather than simple sugars

carbs with a low glycemic index like complex carbohydrates have a more gradual effect rather than spike which helps prevent hyperglycemia

primary symptoms of type 1 diabetes: thirst

polydispia (excessive thirst or compulsive water drinking)

primary symptoms of type 1 diabetes: urination

osmotic diuresis (increased urination due to an excess of solutes in the renal system)

polyurea (excessive urination)

primary symptoms of type 1 diabetes: tiredness

decreased glucose uptake and utilization

primary symptoms of type 1 diabetes: weight loss

tissue loss, fat and protein breakdown

what is HbA1c

glycosylated hemoglobin

what info does HbA1c provide

since it is the measure of glycosylated Hb over the past 2-3 months, it can help diagnose pre-diabetes and diabetes types 1 and 2

how does an insulin pump improve patient care

it helps to mimic pancreatic output by providing a basal output

what is the main thing digested in the stomach

proteins

in what form is glucose stored and what organ stores the vast majority of it

glycogen, and the liver

what 2 hormomes regulate plasma glucose levels

insulin (acts to decrease plasma glucose levels)

glucagon (acts to increase plasma glucose levels)

in the lab we test blood glucose levels at different times, how many minutes pass between glucose level tests

15 minutes

what is the thing getting on the equipment that makes us need to dispose in biowaste

human blood from lancets which are used to test plasma glucose levels on glucometers