BIOL 373 Exam Questions with Correct Answers| Latest Update Guaranteed Success
Homeostasis Relative stability to maintain SIMILAR stable internal enviro and ECF.
Oscillation around set point.
Discovered by walter cannon (fight or flight).
Achieved by nervous + endocrine system.
Chem (secreted into ECF by cells for most comm) and elec signals (nerve and muscle).
Control Local control: close area, localized.
Reflex control: longer distance, neural, endocrine.
Endocrine Chemical hormone released into blood + goes through body. Response =
hormone + correct receptor on cell.
No response = no receptor.
Slower and longer.
Intensity proportional to hormone amount.
Neural Elec signal travel down neuron = translated to chem signal via neurotransmitter to
next cell.
Very fast and short.
Identical in strength.
Intensity proportional to signal frequency.
Neuroendocrine Elec signal travels down neuron = reaches end and secreted into blood.
Response loop Stimulus -> sensor -> input signal [AFFERENT] -> integrating center (brain) ->
output signal [EFFERENT] -> target -> response (reflex).
Feedback mechanisms Negative: stabilizes (homeostatic).
,Feedforward: anticipatory.
Positive feedback: reinforces stimulus (not homeostatic).
Cell specificity Target cell: has receptor for appropriate ligand.
Receptor: proteins within cell (cytoplasm) or project out of membrane (transmembrane).
Ligand: determine what receptor they interact with (signalling molecule).
Receptors Specialized cell/structure in strategic locations convert stimuli into elec signal,
often in ECF.
Receptors have saturation, specificity, and competition with ligands (agonist/antagonist).
Central receptor: close or in brain, 5 senses, chemo/osmo/thermos.
Peripheral receptor: outside brain, baro/proprio (body position)/mechano.
Selectivity One ligand can have several types receptors = diff effects.
EX: epinephrine + Alpha receptor = vasoconstriction, epinephrine + beta2 = vasodilation.
Cells respond signal by changing receptor number or sensitivity:
Increase = more gene expression/regulation.
Decrease = internalize surface receptors/less regulation.
Phosphorylation = change receptor sensitivity.
G protein Signal starts from ligand + receptor binding.
Gamma and beta subunit dissociate free.
Alpha binds to GTP.
Turn off fast when GTP -> GDP and complex reassembles (subunits reattach to alpha).
Cholera toxin Bacteria survive stomach acid = go to small intestine and attach + invade
epithelial cells = make cholera.
, Cholera blocks enzyme activity of G protein and sticks = antagonist = G protein always on = cells
keeps making cAMP = ions secreted in lumen intestine = lots diarrhea.
Intestinal infection from vibrio cholerae from contaminated food/water in developing
countries.
Walter Cannon postulates Nervous system maintains internal enviro = coordinates response
for homeostasis.
Systems maintain tonic activity level via tonic and antagonistic control.
Same chemical signal can have diff effects in diff tissues depending on receptor type present.
Tonic control Regulates physiological parameters by increase or decrease
norepinephrine/signal rate = vasodilation/constriction.
Antagonistic control Neurons control heart rate by speed w/ sympathetic or
parasympathetic nerves.
Nervous system evolution Bilateral symmetry to cephalization (compartmentalized to front).
Consolidation/separation of PNS and CNS: ventral and dorsal nerve cord vs spinal cord and
forebrain.
CNS Brain and spinal cord.
Protected and supported by bony cage (cranium + vertebrae), meninges, CSF.
Meninges Made of 3 layers connective tissue (dura, arachnoid, pia).
Dura: outermost layer, durable
Arachnoid: webby (has gaps), very vascularized, filled w/ CSF.
Pia: follows grooves, delicate.
Spinal (in spinal cord) and cranial (in skull/cranium) meninges.
Homeostasis Relative stability to maintain SIMILAR stable internal enviro and ECF.
Oscillation around set point.
Discovered by walter cannon (fight or flight).
Achieved by nervous + endocrine system.
Chem (secreted into ECF by cells for most comm) and elec signals (nerve and muscle).
Control Local control: close area, localized.
Reflex control: longer distance, neural, endocrine.
Endocrine Chemical hormone released into blood + goes through body. Response =
hormone + correct receptor on cell.
No response = no receptor.
Slower and longer.
Intensity proportional to hormone amount.
Neural Elec signal travel down neuron = translated to chem signal via neurotransmitter to
next cell.
Very fast and short.
Identical in strength.
Intensity proportional to signal frequency.
Neuroendocrine Elec signal travels down neuron = reaches end and secreted into blood.
Response loop Stimulus -> sensor -> input signal [AFFERENT] -> integrating center (brain) ->
output signal [EFFERENT] -> target -> response (reflex).
Feedback mechanisms Negative: stabilizes (homeostatic).
,Feedforward: anticipatory.
Positive feedback: reinforces stimulus (not homeostatic).
Cell specificity Target cell: has receptor for appropriate ligand.
Receptor: proteins within cell (cytoplasm) or project out of membrane (transmembrane).
Ligand: determine what receptor they interact with (signalling molecule).
Receptors Specialized cell/structure in strategic locations convert stimuli into elec signal,
often in ECF.
Receptors have saturation, specificity, and competition with ligands (agonist/antagonist).
Central receptor: close or in brain, 5 senses, chemo/osmo/thermos.
Peripheral receptor: outside brain, baro/proprio (body position)/mechano.
Selectivity One ligand can have several types receptors = diff effects.
EX: epinephrine + Alpha receptor = vasoconstriction, epinephrine + beta2 = vasodilation.
Cells respond signal by changing receptor number or sensitivity:
Increase = more gene expression/regulation.
Decrease = internalize surface receptors/less regulation.
Phosphorylation = change receptor sensitivity.
G protein Signal starts from ligand + receptor binding.
Gamma and beta subunit dissociate free.
Alpha binds to GTP.
Turn off fast when GTP -> GDP and complex reassembles (subunits reattach to alpha).
Cholera toxin Bacteria survive stomach acid = go to small intestine and attach + invade
epithelial cells = make cholera.
, Cholera blocks enzyme activity of G protein and sticks = antagonist = G protein always on = cells
keeps making cAMP = ions secreted in lumen intestine = lots diarrhea.
Intestinal infection from vibrio cholerae from contaminated food/water in developing
countries.
Walter Cannon postulates Nervous system maintains internal enviro = coordinates response
for homeostasis.
Systems maintain tonic activity level via tonic and antagonistic control.
Same chemical signal can have diff effects in diff tissues depending on receptor type present.
Tonic control Regulates physiological parameters by increase or decrease
norepinephrine/signal rate = vasodilation/constriction.
Antagonistic control Neurons control heart rate by speed w/ sympathetic or
parasympathetic nerves.
Nervous system evolution Bilateral symmetry to cephalization (compartmentalized to front).
Consolidation/separation of PNS and CNS: ventral and dorsal nerve cord vs spinal cord and
forebrain.
CNS Brain and spinal cord.
Protected and supported by bony cage (cranium + vertebrae), meninges, CSF.
Meninges Made of 3 layers connective tissue (dura, arachnoid, pia).
Dura: outermost layer, durable
Arachnoid: webby (has gaps), very vascularized, filled w/ CSF.
Pia: follows grooves, delicate.
Spinal (in spinal cord) and cranial (in skull/cranium) meninges.
