BIOL 373 EXAMPREP VERIFIED COMPLETE
QUESTIONS AND ANSWERS PRACTICE
REVIEW
●● What is homeostasis?
Answer: the maintenance of a relatively stable internal environment
(especially ECF)
-oscillation around a set point
●● Who is Walter Cannon?
Answer: the father of physiology
coined the term "homeostasis"
●● What is the difference between local and reflex control?
Answer: Local control = cells near site of change initiate response
Reflex control = cells at a distant site control response
●● What is negative feedback?
Answer: stabilizes variable (correction in opposite direction of change)
●● What is feedforward mechanism?
Answer: control anticipates change
,●● What is positive feedback?
Answer: reinforces stimulus (NOT homeostatic)
●● What are the 3 ways cells can communicate long range?
Answer: endocrine - chemical released in blood and distributed
throughout the body
neural - electrical signal travels down neuron then becomes chemical
which travels to target cell
neuroendocrine - electrical signal travels travel down neuron then
becomes chemical signal that is secreted into the blood
●● What determines what type of receptors ligands will interact with?
Answer: chemical properties of the ligands
surface receptor = hydrophillic/lipophobic/water soluble
intracellular receptor = hydrophobic/lipophillic/water insoluble
●● How can cells change their response to different signals?
Answer: change receptor number or sensitivity
increase = increase expression of gene that codes for receptor or increase
expression of receptor proteins on cell surface
decrease = internalize surface receptors
change receptor sensitivity = phosphorylation
,●● How is a GPCR activated?
Answer: -signal molecule binds to receptor and causes conformational
change
-activates G protein by exchanging GDP for GTP
-when GTp binds alpha subunit+GTP dissociates from the B and gamma
subunits
-G alpha subunit turns itself off by hydrolizing GTP
●● What affect does Cholera Toxin have on the inactivation of G alpha
subunit?
Answer: -blocks GTP hydrolysis (GTPase activity)
-results in persistent activation of adenylate cyclase
●● What are Cannon's Postulates?
Answer: -the nervous system has a role in maintaining the 'fitness' of the
internal environment
-some systems under tonic control
-some systems are under antagonistic control
-one chemical signal can have different effects in different tissues
●● Specificity of neural vs. endocrine control
, Answer: neural = single target cell or limited number of adjacent target
cells
endocrine = exposed to all cells but only those which receptors responsd
●● Nature of signal for neural vs. endocrine control
Answer: neural = electrical signal that turns chemical (neurotransmitter)
endocrine = chemical signals
●● Speed of neural vs. endocrine control
Answer: neural = very rapid
endocrine = much slower than neural responses
●● Duration of action in neural vs. endocrine control
Answer: neural = usually very short
endocrine = longer than neural responses
●● Coding for stimulus intensity in neural vs endocrine control
Answer: neural = each signal is identical in strength. Increase intensity
by increasing frequency
endocrine = intensity proportional to amount of hormone secreted
●● What are the evolutionary trends in the nervous system?
QUESTIONS AND ANSWERS PRACTICE
REVIEW
●● What is homeostasis?
Answer: the maintenance of a relatively stable internal environment
(especially ECF)
-oscillation around a set point
●● Who is Walter Cannon?
Answer: the father of physiology
coined the term "homeostasis"
●● What is the difference between local and reflex control?
Answer: Local control = cells near site of change initiate response
Reflex control = cells at a distant site control response
●● What is negative feedback?
Answer: stabilizes variable (correction in opposite direction of change)
●● What is feedforward mechanism?
Answer: control anticipates change
,●● What is positive feedback?
Answer: reinforces stimulus (NOT homeostatic)
●● What are the 3 ways cells can communicate long range?
Answer: endocrine - chemical released in blood and distributed
throughout the body
neural - electrical signal travels down neuron then becomes chemical
which travels to target cell
neuroendocrine - electrical signal travels travel down neuron then
becomes chemical signal that is secreted into the blood
●● What determines what type of receptors ligands will interact with?
Answer: chemical properties of the ligands
surface receptor = hydrophillic/lipophobic/water soluble
intracellular receptor = hydrophobic/lipophillic/water insoluble
●● How can cells change their response to different signals?
Answer: change receptor number or sensitivity
increase = increase expression of gene that codes for receptor or increase
expression of receptor proteins on cell surface
decrease = internalize surface receptors
change receptor sensitivity = phosphorylation
,●● How is a GPCR activated?
Answer: -signal molecule binds to receptor and causes conformational
change
-activates G protein by exchanging GDP for GTP
-when GTp binds alpha subunit+GTP dissociates from the B and gamma
subunits
-G alpha subunit turns itself off by hydrolizing GTP
●● What affect does Cholera Toxin have on the inactivation of G alpha
subunit?
Answer: -blocks GTP hydrolysis (GTPase activity)
-results in persistent activation of adenylate cyclase
●● What are Cannon's Postulates?
Answer: -the nervous system has a role in maintaining the 'fitness' of the
internal environment
-some systems under tonic control
-some systems are under antagonistic control
-one chemical signal can have different effects in different tissues
●● Specificity of neural vs. endocrine control
, Answer: neural = single target cell or limited number of adjacent target
cells
endocrine = exposed to all cells but only those which receptors responsd
●● Nature of signal for neural vs. endocrine control
Answer: neural = electrical signal that turns chemical (neurotransmitter)
endocrine = chemical signals
●● Speed of neural vs. endocrine control
Answer: neural = very rapid
endocrine = much slower than neural responses
●● Duration of action in neural vs. endocrine control
Answer: neural = usually very short
endocrine = longer than neural responses
●● Coding for stimulus intensity in neural vs endocrine control
Answer: neural = each signal is identical in strength. Increase intensity
by increasing frequency
endocrine = intensity proportional to amount of hormone secreted
●● What are the evolutionary trends in the nervous system?
