101 Lab 5 Tutor template 2011.pdf

8/14/2019 101 Lab 5 Tutor template 2011.pdf

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BIOSCI 101 Lab 5

Determination of Blood GlucoseThis course has six labs:

1. Enzymology

2. Gene Expression

3. Genetics

4. Evolution

5. Blood Glucose

6. Photosynthesis

Human endocrine glandsA gland thatsecreteshormones intothe bloodstream

The endocrinetissue involved

in themaintenance ofblood glucoselevel (BGL) is.

THE PANCREAS


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Glucose Absorption

IntestinalLumen

+

Na+Na+

+

Na+

Na+lucose

IntestinalEpithelium

Na+ sodium ion

Na+-dependentlucose

ACTIVE

INCREASE BLOODGLUCOSE LEVELS

transporter

Na+

Na+

Na+

LocalCapillary

DIFFUSION

BGLs are regulated by insulin and glucagon

The pancreas has both endocrine and exocrinefunctions Exocrine function: secretion of bicarbonate ions and

digestive enzymes.

Endocrine function: insulin and glucagon secreted byislets of Langerhans

Within the islet:

cells secrete glucagon

cells secrete insulin


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Glucagon

Glucagon is a 29aa polypeptide

cells produce glucagon in response to LOWBGL

RAISES blood glucose levels by:

-

- signalling the liver cells to break down glycogenpolymers into monomeric glucose

InsulinInsulin is a 51aa polypeptide

cells produce insulin in response to HIGHBGL

LOWERS blood glucose levels by:

- timulatin all bod cells exce t brain cells totake up glucose

Has numerous other effects such as:

- Promoting storage of fuel e.g. glycogen and fat

- Stimulating glycogen synthesis


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The action of insulin

Insulin binds to insulin receptors

This results in an increase in the number of glucosetransporters at the cell membrane

uptake of glucose is increased

1 insulin binds to Rc 3 Insulin mediateduptake of glucose

The action of insulin

insulin

insulin Rc

glucose

glucosetransporter 2 Rc activates glucose

transporter pool

4 Insulin levelsdecrease,glucosetransportersare recycled

endosome


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Glucose homeostasis maintained byinsulin and glucagon

Hypoinsulinism: diabetes mellitus

Hereditary factors and obesity play a role in its development

High blood sugar levels sugar excreted in the urine

Symptoms: excessive urination,excessive thirst, weight lossand tiredness

If severe: fat substitutes for glucose as major fuelsource production of acidic metabolites lifethreatening lowering of blood pH


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Type I diabetes

Type I diabetes mellitus (insulin-dependent diabetes)

-

- Usually appears in childhood

- Treatment: insulin injections

Normal pancreas Diabetic pancreas

Type II diabetes

Type II diabetes mellitus (non-insulin dependent)

- Usually due to target cells having a decreasedresponsiveness to insulin

- Usually occurs after age 40 risk increases with age

- Accounts for over 90% of diabetes cases


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Glucose levels in blood

Normal Glucose levels:. .

3.3 7.9 mmol/L Random

Indicators of Diabetes - Classic symptoms:- Plasma glucose > 11.0 mmol/L- Fasting glucose > 7.0 mmol/L twice

- an om g ucose > . mmo twice- 2 hour plasma glucose >11.0 mmol/L twice

in a GTT

Todays lab

Preparation of a standard curve using knownu u

(shared spectro)

Diagnose a virtual patient

ssesse group scuss on


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1. Standard Curves

Ensure glucose stock is well mixed

Zero spectro using cuvette with dH20

- Clear sides to light path- Dont write on the cuvette

Timin is critical - the reaction CANNOT be

Once zeroed the spectro will read automatically

stopped and every tube needs to incubate for 10

minutes work together as there is only 1 spec/4students

Plot absorbance against [gluc] (mol)

ONE PIECE OF GRAPH PAPER FOR TWO GRAPHS

2. Diagnosis

Ensure sam les are well-mixed

Fill out table on p5.8 remember to account forthe dilution factor

Write patient colour on graph and diagnose


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Graphs

- Title (Not y verus x)- Axis labels- Units-- your patient colour and diagnosis

(diabetic OR normal)

Graphs

1. Glucose standard curve Abs

glucose umol

2. Glucose tolerance test

- Draw a line of best fit

glucose mmol

time

Patient colourDiagnosis (diabetic or normal)


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Cleanup Instructions for this lab

1. Place blue/white pipette tips in labelled containers bysink, return beaker to your bench.2. Place

a) GOR flaskb) Cuvettesc) standard glucose test tube

in labelled containers by sink3. Place glass test tubes in bin on trolley by sink.

. m y ce uc e an s ac on s e enc .5. Stack white tray on side bench.

LEAVE UNKNOWN GLUCOSE TUBES LABELLED 1-6IN TEST TUBE RACK AT YOUR BENCH

FINALCHECKLIST:

with discussion mark attached to twographs) - name; stream number; bench (#)

Clean Up instructions on whiteboard.

re aration for lab 6 ( re are re-

assignment) Wash hands before leaving


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Dear Tutors

Next slides please use if yourequire them in your teaching

MASTER SLIDE


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Glucose Std Curve

0.5

0.6

0.2

0.3

0.4

Absorbance

0

0.1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

umols glucose

Glucose Tolerance test

16

18

6

8

10

12

14

glucose(umol/ml)

0

2

0 50 100 150 200 250 300 350

Minutes after ingestion


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MASTER SLIDE

MASTER SLIDE


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MASTER SLIDE

101 Lab 5 Tutor template 2011.pdf

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