BIOL 373 Midterm 1 (Unit 1, 2 and 3)
Exam Solved Correctly To Score A+!!!
What is physiology? CORRECT ANSWERS the science of the function of living systems
What is homeostasis? CORRECT ANSWERS the maintenance of a relatively stable
internal environment (especially ECF)
-oscillation around a set point
Who is Walter Cannon? CORRECT ANSWERS the father of physiology
coined the term "homeostasis"
What is the difference between local and reflex control? CORRECT ANSWERS Local
control = cells near site of change initiate response
Reflex control = cells at a distant site control response
What is negative feedback? CORRECT ANSWERS stabilizes variable (correction in
opposite direction of change)
What is feedforward mechanism? CORRECT ANSWERS control anticipates change
What is positive feedback? CORRECT ANSWERS reinforces stimulus (NOT
homeostatic)
What are the 3 ways cells can communicate long range? CORRECT ANSWERS
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? CORRECT
ANSWERS 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? CORRECT ANSWERS
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? CORRECT ANSWERS -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? CORRECT
ANSWERS -blocks GTP hydrolysis (GTPase activity)
-results in persistent activation of adenylate cyclase
What are Cannon's Postulates? CORRECT ANSWERS -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 CORRECT ANSWERS 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 CORRECT ANSWERS neural =
electrical signal that turns chemical (neurotransmitter)
endocrine = chemical signals
Speed of neural vs. endocrine control CORRECT ANSWERS neural = very rapid
endocrine = much slower than neural responses
Duration of action in neural vs. endocrine control CORRECT ANSWERS neural =
usually very short
endocrine = longer than neural responses
Coding for stimulus intensity in neural vs endocrine control CORRECT ANSWERS
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? CORRECT ANSWERS
bilateral symmetry -> cephalization -> consolidation of PNS -> nerves -> ventral nerve
cord -> dorsal nerve cord -> spinal cord -> increasing role of forebrain
Describe the development of the Human CNS CORRECT ANSWERS 4 weeks: anterior
end of neural tube specialized into 3 regions (forebrain, midbrain, hindbrain) and spinal
cord
6 weeks: neural tube differentiates into major brain regions present at birth
forebrain -> diencephalon, cerebrum
midbrain
hindbrain -> medulla oblongata, cerebellum, and pons
, 11 weeks: growth of cerebrum much more rapid than that of other regions
birth: cerebrum covers most of other brain regions; convoluted surface due to rapid
growth in confined space
What structures provide protection and support for CNS? CORRECT ANSWERS -
surrounded by bony cage: cranium
-3 layers of connective tissues: meninges
-fluid between layer: cerebrospinal fluid
What are the meninges? CORRECT ANSWERS layers of connective tissue that
surround the brain and spinal cord
dura mater = outermost layer
arachnoid mater = middle layer
pia mater = innermost layer
Describe the fluid filled cavities in the CNS CORRECT ANSWERS -ventricles within the
brain and hollow central canal within the spinal cord
-2 lateral ventricles and 2 descending ventricles that extend through in brain stem
-CSF in ventricles continuous with fluid in central canal of spinal cord
-CSF is secreted by the choroid plexus within each ventricle (choroid plexuses produce
~500mL of CSF/day)
Extracellular fluids of the CNS CORRECT ANSWERS 1. interstitial fluid - surrounds
neurons and glial cells
2. plasma - within cerebral blood vessels
3. cerebrospinal fluid - within ventricular system and bathes external surfaces of the
brain between meninges (removed and replaced ~4 times per day)
Plasma vs. CSF CORRECT ANSWERS CSF has:
- lower K+, Ca2+, HCO3-, glucose, pH
-similar Na+
-very low protein, no blood cells (presence of elevated protein or blood cells collected
from CSF indicates infection)
Glial cells of the CNS CORRECT ANSWERS 1. oligodendrocytes - form myelin sheaths
within CNS "white matter"
2. microglia - immune cell lineage
3. astrocytes - regulate local ECF by releasing chemicals (numerous in the brain)
4. ependymal cells - creates barrier between compartments (decide what ends up in
CSF)
What are the special features of the cerebral vasculature? CORRECT ANSWERS 1.
astrocyte foot processes- secrete paracrine factors that promote tight junction formation
2. tight junctions- prevent solute movement between endothelial cells
Exam Solved Correctly To Score A+!!!
What is physiology? CORRECT ANSWERS the science of the function of living systems
What is homeostasis? CORRECT ANSWERS the maintenance of a relatively stable
internal environment (especially ECF)
-oscillation around a set point
Who is Walter Cannon? CORRECT ANSWERS the father of physiology
coined the term "homeostasis"
What is the difference between local and reflex control? CORRECT ANSWERS Local
control = cells near site of change initiate response
Reflex control = cells at a distant site control response
What is negative feedback? CORRECT ANSWERS stabilizes variable (correction in
opposite direction of change)
What is feedforward mechanism? CORRECT ANSWERS control anticipates change
What is positive feedback? CORRECT ANSWERS reinforces stimulus (NOT
homeostatic)
What are the 3 ways cells can communicate long range? CORRECT ANSWERS
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? CORRECT
ANSWERS 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? CORRECT ANSWERS
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? CORRECT ANSWERS -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? CORRECT
ANSWERS -blocks GTP hydrolysis (GTPase activity)
-results in persistent activation of adenylate cyclase
What are Cannon's Postulates? CORRECT ANSWERS -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 CORRECT ANSWERS 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 CORRECT ANSWERS neural =
electrical signal that turns chemical (neurotransmitter)
endocrine = chemical signals
Speed of neural vs. endocrine control CORRECT ANSWERS neural = very rapid
endocrine = much slower than neural responses
Duration of action in neural vs. endocrine control CORRECT ANSWERS neural =
usually very short
endocrine = longer than neural responses
Coding for stimulus intensity in neural vs endocrine control CORRECT ANSWERS
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? CORRECT ANSWERS
bilateral symmetry -> cephalization -> consolidation of PNS -> nerves -> ventral nerve
cord -> dorsal nerve cord -> spinal cord -> increasing role of forebrain
Describe the development of the Human CNS CORRECT ANSWERS 4 weeks: anterior
end of neural tube specialized into 3 regions (forebrain, midbrain, hindbrain) and spinal
cord
6 weeks: neural tube differentiates into major brain regions present at birth
forebrain -> diencephalon, cerebrum
midbrain
hindbrain -> medulla oblongata, cerebellum, and pons
, 11 weeks: growth of cerebrum much more rapid than that of other regions
birth: cerebrum covers most of other brain regions; convoluted surface due to rapid
growth in confined space
What structures provide protection and support for CNS? CORRECT ANSWERS -
surrounded by bony cage: cranium
-3 layers of connective tissues: meninges
-fluid between layer: cerebrospinal fluid
What are the meninges? CORRECT ANSWERS layers of connective tissue that
surround the brain and spinal cord
dura mater = outermost layer
arachnoid mater = middle layer
pia mater = innermost layer
Describe the fluid filled cavities in the CNS CORRECT ANSWERS -ventricles within the
brain and hollow central canal within the spinal cord
-2 lateral ventricles and 2 descending ventricles that extend through in brain stem
-CSF in ventricles continuous with fluid in central canal of spinal cord
-CSF is secreted by the choroid plexus within each ventricle (choroid plexuses produce
~500mL of CSF/day)
Extracellular fluids of the CNS CORRECT ANSWERS 1. interstitial fluid - surrounds
neurons and glial cells
2. plasma - within cerebral blood vessels
3. cerebrospinal fluid - within ventricular system and bathes external surfaces of the
brain between meninges (removed and replaced ~4 times per day)
Plasma vs. CSF CORRECT ANSWERS CSF has:
- lower K+, Ca2+, HCO3-, glucose, pH
-similar Na+
-very low protein, no blood cells (presence of elevated protein or blood cells collected
from CSF indicates infection)
Glial cells of the CNS CORRECT ANSWERS 1. oligodendrocytes - form myelin sheaths
within CNS "white matter"
2. microglia - immune cell lineage
3. astrocytes - regulate local ECF by releasing chemicals (numerous in the brain)
4. ependymal cells - creates barrier between compartments (decide what ends up in
CSF)
What are the special features of the cerebral vasculature? CORRECT ANSWERS 1.
astrocyte foot processes- secrete paracrine factors that promote tight junction formation
2. tight junctions- prevent solute movement between endothelial cells
