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BIOB30 Lecture 1

Biological Sciences
Course Code
Catherine Nash

of 3
Mammalian Physiology Lecture 1
Claude Bernard
-1st physiologist
-discover homeostasis
how body maintains homeostasis
how body adapts to changes in external and internal environment
-maintain constant water & temperature level
-chemical level includes neurotransmitter & hormone level
Some of Bernard’s discoveries
1. fat
2. glucose
3. skin temperature is controlled by mechanism distant from skin, which is the brain
4. curare, muscle relaxation
5. oxygen to haemoglobin
How the body maintains homeostasis
-each compartment is linked by circulatory, nervous, & endocrine system
-comprise of different salt, sugar, & protein level
-how the body balances the above components between these compartments
-disease arrives when homeostasis fails
-increase in salt concentration
-affect blood pressure
-change in glucose level
-drinking and eating are internal compensation
-temperature is external compensation
Diabetes (insulin dependent)
-glucose intake
-results in changes in salt balance, which affects internal and external compartments
-slurred speech, fainting, coma, blindness
-homeostasis failure may result in cancer
1. Approach
-top to down approach
-molecular biology equipment
-genome was revealed
-fewer genes from protein
-indicate each gene encodes at least 2 times to protein
Apply an integrated approach
-multiple methods
-multi-disciplinary (top to down, down to top)
2. Hypothesis (assume)
-food is dependent on temperature (dependent variable)
-temperature is independent variable
Non-testable hypothesis
-birds feel hungrier in winter than summer
-feeling is subjective, not a testable hypothesis
3. Experimental design
-as you move down the chart, the method becomes more expensive and timely
Test Tube
Advantages (+)
-easy to control
-fewer ethical issue
-molecular mechanism
Disadvantages (-)
-less physiological
Animal (+)
-more physiological
-fewer ethical issue than human
-less interspecies variability
-food environment is controlled for each individual
-cannot control every variable for human
-different mechanism than human
-species are different than human
-cannot isolate molecules
Human (+)
-more practical and applicable, such as medical research and clinical trial
-inter-patient variability
-take a long time
3. Experimental design factors
i. Control temperature
-summer and winter difference
ii. Number of animals
-equal number
-a greater number, 10 over 3 birds to ensure statistical variability
iii. Control food intake
-equal amount of food
-equal height of the food location
-equal availability
iv. Habitat
-caged in groups instead of alone
4. Interpretation
i. Variability between subjects
-same age, sex, lifestyle, ethnic origin
ii. Psychological bias
-patients want the hypothesis to work
-use placebo to perform single blind experiment
-researchers want the hypothesis to work
-use cross-over double blind study so both patients and researchers are blinded to the variable
Truth can change
-new technology
-were given to pregnant women
-lead to kids born with malformation
-the drug is now treated for cancer