Lab test 1 Flashcards by ghita moustaki

define homeostatis

maintaining relatively constant internal conditions/ continous balance in our bodies

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how do the nervous and endocrine system regulate homeostasis

nervous system sends messages between neurons to signal any stimulus in the body

endocrine system releases hormones to regulate the activity of cells

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What is the difference between a positive and negative feedback

negative: response diminishes the original stimulus to bring you back to homeostatic range (insulin/glucagon)

positive: enhances the stimulus= brings you away from homeostatic range (contractions during birth)

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What are the components of negative feeback mechanism

1-receptor
2-control center
3-effector

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What is the purpose of a receptor

detects the stimulus (fluctuation above/below range)

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What is the purpose of a control center

determines the appropriate response to stimulus

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What is the purpose of an effector

carries out response determined by the control center

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What kind of pathway does the receptor use to communicate with the control center

afferent pathway

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What kind of pathway does the the control center use to communicate with the effector

efferent pathway

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What organs are involved in the elimination of waste products

urinary system= kidneys
respiratory system= lungs
digestive system= large intestine

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what is the relationship between glucose and atp (pathway)

cellular respiration

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What is insulin

hormone secreted by pancreas that decrease the glucose concentration in blood

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what is glucagon

hormone secreted by pancreas that increases the concentration of glucose in the blood

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what is ADH

hormone secreted by pituary glands that increase the abosrption of water in the blood to reduce the concentration of sodium = lower blood pressure

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What organs and organ system are involved in blood glucose homeostasis

liver, pancreas, muscle/adipose tissue
endocrine system

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How many negative feedback mechanisms are utilized to maintain blood glucose homeostasis

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what are the 2 antagonistic hormones

insulin and glucagon

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Aside from removing waste what is the other function of the urinary system

regulate body fluid levels

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How do the constituents found in urine reflect what your body is doing to maintain homeostasis?

If urine is concentrated in ions it means that its low in water=dehydrated individual
ADH increased the water intake of blood which causes urine to be less diluted=more intense color and increased specific gravity
maintains homeostasis of body fluids and blood pressure

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What does specific gravity of urine measure?

ratio of liquid to same volume of distilled water

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What can you infer from a relatively high or low specific gravity of a patient’s urine?

high= individual is dehydrated
low= too much water intake

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How does the respiratory system regulate blood pH?

increase in CO2 concentration= acidosis= breathing pattern is increased to expel excess CO2

decrease in CO2 concentration= alkalosis= breathing pattern is slowed down to let carbon dioxide accumulate in the blood

what every urinometer reading is always compared to. What is this fluid and it’s specific gravity?

compared to 1.002-1.003

What is diabetes mellitus?

endocrine disorder that affects blood glucose concentration

what is the difference between Type 1 and 2 diabetes.

type 1= insufficient production of insulin (genetic) type 2= decreased response to insulin in cells of certain tissue

what are the symptoms of an untreated diabetic.

hunger, fatigue, dehydration

What type of output from the body help diagnose diabetes mellitus?

plasma from the blood and urine

What is the Oral Glucose Tolerance Test (OGTT)?

test for diabetes analyzes the blood plasma to determine the capacity of an individual to clear glucose in their blood results will signal if individual has either a delay in insuin excretion or delay in glucose absorption

What is the general procedure of the OGTT for a patient?

patient fasts for 8-14hrs prior first blood sample is drawn at hour 0 (serves as a baseline) patient drinks glucose solution after 2 hours blood drawn (sample reveals glucose tolerance of patient) plasma of both sample is isolated and compared

For the OGTT, what is the concentration of glucose (mM) for a patient with normal tolerance? With diabetes?

normal: concentration below 7.8 mM pre-diabetic: between 7.8-11.1 mM diabeti: above 11.1 mM

What is glycosuria?

when diabetics have glucose present in their urine

What urine constituents are abnormal in a patient with untreated diabetes type 1?

glucose

What are the two reactions in the Hexokinase Reagent Method?

rxn 1: phosphorylation of glucose by hexokinase rxn 2: glucose-6-phosphate is oxidized by G6P-DH in presence of NAD+ which makes NADH

Why is the hexokinase reagent method appropriate in evaluating glucose in blood sample

the 2 rxns produce a glucose specific signal that is proportional to the amount of glucose in the sample

What is the Benedict’s reagent method? How does a positive or negative result look and what do these results infer

tests for the presence of reduction sugars reduction sugars will react with the solution and form precipitate that will change the color of the solution. the more positive=high concentration of sugars negative=low concentration

How does the Benedicts reagent differ from the Hexokinase Reagent Method?

Hexokinase= quantitative Benedicts=qualitative

Why was galactose used in the lab?

to test the specifity of the method since galactose is a stereoisomer of glucose and will produce background noise

Define diffusion

spontaneous process caused by concentratient gradient which causes net mouvement of a solution from are of high concentration to low concentration

Define osmosis

diffusion of water through a semi permeable membrane fueld by osmotic gradient spontaneous rxn moves from low to high concentration

Define concentration gradient

different concentrations on each sides of membrane

Define dynamic equilibrium.

when rate of frwd rxn is the same as rate of reverse rxn

what is the difference between simple diffusion and facilitated diffusion

simple diffusion occurs for non polar substances that can easily diffuse through plasma membrane faciliated diffusion is when polar bodies use transport proteins to exit and enter the cell since the hydrophobic are of bilayer disables them from doing so

What is the effect of adding salts of osmolarity

define terms isotonic, hypotonic, and hypertonic when comparing solutions separated by a membrane. What effect might these solutions have on cell shape?

isotonic= not net mouvemet of water and cell remains as is hypotonic= net gain of water, cell is lysed hypertonic= net loss of water, cell is shriveled

how does size and polarity of penetrating solutes can affect the speed at which they alter tonicity and consequently cell shape.

increasing size and polarity will slow down the rate

what is the function of enzymes

proteins that catalyze chemical rxn

How are enzymes affected by changes in pH and temperature?

change in pH and temperature will cause the tertiary structure of protein to unravel= will not function anymore

what is the function of catalase enzyme and where it is found

catalase breakdowns the H2O2 formed in cells into harmless products found in liver

what reaction does catalase catalyze? What is the substrate? The products?

oxidoreductase rxn substrate: h2o2 products: H2 and O2

what is the purpose of doing control runs

to make sure the enzyme is functionning properly

What is the difference between accuracy and precision

accuracy : how close the measurements made are to the actual value precision: how close repeated measurements are to each other

True or false accuracy tells you about systematic error/bias

true

True or false precision tells you about systematic error/bias

false, tells you about random/technical error