BIOL373 – Final Exam Review Material
Normal plasma pH - correct answer 7.38-7.42. Too acidic will depress NS, too basic will
hyperexcite. H+ concs closely regulated. Disturbances associated with K+ disturbances.
Buffers - correct answer Bicarbonate (HCO3-) in ECF, proteins, hemoglobin, phosphates in cells,
phosphates and ammonia in urine. First line of defence, become overwhelmed quickly if pH
moves too far out of normal range.
Acid inputs and excretion - correct answer Input from diet (eg fatty acids, a.as), and metabolism
(CO2, lactic acid, ketoacids).
Excreted through ventilation (mostly) and renal
Main source of H+ in body - correct answer CO2 + H2O <-> H2CO3 <-> HCO3- + H+
Carbonic acid intermediate dissociates very quickly.
Usually a slow reaction, accelerated in some cells by carbonic anhydrase.
Renal acid balance - correct answer Direct: excretes or reabsorbs H+ ions
Indirect: changes rate of HCO3- excretion or reabsorption.
Slow but very effective
Effects of abnormal ventilation - correct answer Hypoventilation: CO2 buildup, respiratory
acidosis, detected by central and aortic chemoreceptors.
Hyperventilation: CO2 decreases, respiratory alkalosis, less common (due to over artificial
ventilation, or anxiety attack etc)
If the cause of pH imbalance is respiratory, can only use renal mechanisms to fix it.
Respiratory compensation for metabolic acidosis - correct answer Increase in plasma H+
noticed by carotid and aortic chemoreceptors, increase in plasma CO2 noticed by central
chemoreceptors. Integrated in resp. control centers, stimulate muscles of ventilation to
increase rate and depth of breathing. Decrease in plasma H+/CO2 then sends neg. feedback
through chemoreceptors.
Direct kidney compensation for acidosis - correct answer Mostly in PROX TUBULE. Transports
H+ out apical side (using H+/K+ transporter), combines with HPO4(2-) in urine and is excreted.
Nitrogenous compounds (eg a.as) combine with H+ to make ammonium in epithelial cells,
excreted out apical side via Na+/NH4+ antiport.
Indirect kidney compensation for acidosis - correct answer Mostly in PROX TUBULE. Reabsorbs
HCO3-. No apical HCO3- transporters, so must cross as CO2 and then be converted using
,carbonic anhydrase in the cell. Then, Na+/HCO3- symport on basal side pumps into ECF to help
as a buffer.
Role of Ia cells in acidosis - correct answer Mixed between P cells in DISTAL nephron. Secrete
H+ and reabsorb bicarb. Use apical H+ ATP-ase, apical H+/K+ antiport ATP-ase, basal Cl-/HCO3-
antiport.
Role of Ib cells in alkalosis - correct answer Mixed between P cells in DISTAL nephron. Secrete
bicarb and reabsorb H+. Use basal H+ ATP-ase, basal H+/K+ antiport ATP-ase, apical Cl-/HCO3-
antiport.
Metabolic acidosis causes - correct answer Increase in H+ input, presence of toxins,
lactic/ketoacidosis, or loss of HCO3- through diarrhea
Metabolic alkalosis causes - correct answer Loss of H+ from stomach (ie vomiting), or increase
in HCO3- due to overuse of antacids
Hormone overview - correct answer Chemical messenger secreted into blood by specialized
cells. Regulate longterm/ongoing functions, endogenous/exogenous sources. Acts on target by
regulating enzyme activity/ion transport/gene expression.
Slower acting, but powerful and persistent
First experiments in endocrinology - correct answer Done on male chickens. After castration
and reimplantation of testes, realized connection was not neural, since still functioned.
Brown-Sequard experiments - correct answer 19th century, injected self with ground-up testes,
claimed caused sexual rejuvenation and extended life etc. First applied endo. experiment
Classic endocrine experiments - correct answer Ablation: removal of suspected gland.
Replacement: gland/extract is returned.
Create situation of excess, isolate hormone, characterize chemically.
Use bioassays, biological systems, introduce hormone and monitor cellular response
Exo vs endocrine gland - correct answer Exocrine: has a duct, secretes to surface
Endocrine: ductless, must secrete right to capillaries
Classic hormone - correct answer Secreted into blood by group of modified epithelial cells
formed into glands, travel long distances to target, act at very low concentrations
Non-classic hormones - correct answer Secreted by neurons, immune cells, endocrine cells in
gut. Act more locally, diffuse through ECF (eg testosterone). Clearly ID'd as hormones in some
contexts, but also secreted in CNS as neurotransmitters
, Hormone action - correct answer Act via receptors (extracellular or in cytoplasm), cells can
increase/decrease sensitivity by changing receptor number and activity. Equilibrium between
free and bound hormone, need to drop blood concs to drop hormone activity.
Hormone half life - correct answer Inactivated on way through liver/kidney, which determines
halflife. Nonspecific ECF proteins also break down hormones
Ways to classify hormones - correct answer Source, mech of action (GPCR, RTKs, intracellular),
chemistry (a.a, peptide, steroid)
Protein/peptide hormones - correct answer Largest group. Range of size (3 a.as to
glycoprotein). Short halflife esp for smaller (seconds to minutes). Hydrophilic, synth+released
through secretory path. Primary transcript long pre-prohormone, processed lots until stored in
vesicles as prohormone. Released on signal. Act with GPCR/RTK/ion channel, usually rapid
effects (eg enzyme phosphorylation).
Amine hormones - correct answer Derived from tryptophan (melatonin) or tyrosine (thyroid
and catecholamines). Catecholamines (epi, norepi, dopa) are neurohormones, act via
membrane receptors. Thyroid hormones (T3, T4) are intracellular, have iodine molecules
incorporated
Steroids - correct answer Derived from cholesterol, only made in a few organs that express
sidechain cleavage enzyme (adrenal cortex, gonads, placenta). Small, lipophilic, synthesized on
demand by steroidogenic enzymes in smooth ER/inner mitochondrial membrane. Classic
receptors are in cytoplasm/nucleus
Steroid synthesis sites - correct answer Testosterone made in testes
Estradiol, progesterone made in ovaries
Cortisol, aldosterone made in adrenal cortex
Steroid mechanism of action - correct answer Diffuses through membrane, forms a complex
with receptor, imported to nucleus. Receptor-hormone complex then binds to DNA as a
transcription factor, activating/repressing gene expression. Slow.
Simple endocrine reflex (low Ca2+ eg) - correct answer Stimulus (low Ca2+) detected by
integrating center (parathyroid cell). Hormone (parathyroid) secreted in response. Hormone
travels through blood to target (bone and kidney), target responds (eg increasing Ca2+
reabsorption/resorption).
The integrating center both acts as the sensor and the hormone releaser
Complex neuroendocrine reflex - correct answer Stimulus detected by sensor, sensory neuron
carries information to integrating center. Then an efferent neuron or neurohormone carries
signal to endocrine integrating center, releases a hormone, etc.
Normal plasma pH - correct answer 7.38-7.42. Too acidic will depress NS, too basic will
hyperexcite. H+ concs closely regulated. Disturbances associated with K+ disturbances.
Buffers - correct answer Bicarbonate (HCO3-) in ECF, proteins, hemoglobin, phosphates in cells,
phosphates and ammonia in urine. First line of defence, become overwhelmed quickly if pH
moves too far out of normal range.
Acid inputs and excretion - correct answer Input from diet (eg fatty acids, a.as), and metabolism
(CO2, lactic acid, ketoacids).
Excreted through ventilation (mostly) and renal
Main source of H+ in body - correct answer CO2 + H2O <-> H2CO3 <-> HCO3- + H+
Carbonic acid intermediate dissociates very quickly.
Usually a slow reaction, accelerated in some cells by carbonic anhydrase.
Renal acid balance - correct answer Direct: excretes or reabsorbs H+ ions
Indirect: changes rate of HCO3- excretion or reabsorption.
Slow but very effective
Effects of abnormal ventilation - correct answer Hypoventilation: CO2 buildup, respiratory
acidosis, detected by central and aortic chemoreceptors.
Hyperventilation: CO2 decreases, respiratory alkalosis, less common (due to over artificial
ventilation, or anxiety attack etc)
If the cause of pH imbalance is respiratory, can only use renal mechanisms to fix it.
Respiratory compensation for metabolic acidosis - correct answer Increase in plasma H+
noticed by carotid and aortic chemoreceptors, increase in plasma CO2 noticed by central
chemoreceptors. Integrated in resp. control centers, stimulate muscles of ventilation to
increase rate and depth of breathing. Decrease in plasma H+/CO2 then sends neg. feedback
through chemoreceptors.
Direct kidney compensation for acidosis - correct answer Mostly in PROX TUBULE. Transports
H+ out apical side (using H+/K+ transporter), combines with HPO4(2-) in urine and is excreted.
Nitrogenous compounds (eg a.as) combine with H+ to make ammonium in epithelial cells,
excreted out apical side via Na+/NH4+ antiport.
Indirect kidney compensation for acidosis - correct answer Mostly in PROX TUBULE. Reabsorbs
HCO3-. No apical HCO3- transporters, so must cross as CO2 and then be converted using
,carbonic anhydrase in the cell. Then, Na+/HCO3- symport on basal side pumps into ECF to help
as a buffer.
Role of Ia cells in acidosis - correct answer Mixed between P cells in DISTAL nephron. Secrete
H+ and reabsorb bicarb. Use apical H+ ATP-ase, apical H+/K+ antiport ATP-ase, basal Cl-/HCO3-
antiport.
Role of Ib cells in alkalosis - correct answer Mixed between P cells in DISTAL nephron. Secrete
bicarb and reabsorb H+. Use basal H+ ATP-ase, basal H+/K+ antiport ATP-ase, apical Cl-/HCO3-
antiport.
Metabolic acidosis causes - correct answer Increase in H+ input, presence of toxins,
lactic/ketoacidosis, or loss of HCO3- through diarrhea
Metabolic alkalosis causes - correct answer Loss of H+ from stomach (ie vomiting), or increase
in HCO3- due to overuse of antacids
Hormone overview - correct answer Chemical messenger secreted into blood by specialized
cells. Regulate longterm/ongoing functions, endogenous/exogenous sources. Acts on target by
regulating enzyme activity/ion transport/gene expression.
Slower acting, but powerful and persistent
First experiments in endocrinology - correct answer Done on male chickens. After castration
and reimplantation of testes, realized connection was not neural, since still functioned.
Brown-Sequard experiments - correct answer 19th century, injected self with ground-up testes,
claimed caused sexual rejuvenation and extended life etc. First applied endo. experiment
Classic endocrine experiments - correct answer Ablation: removal of suspected gland.
Replacement: gland/extract is returned.
Create situation of excess, isolate hormone, characterize chemically.
Use bioassays, biological systems, introduce hormone and monitor cellular response
Exo vs endocrine gland - correct answer Exocrine: has a duct, secretes to surface
Endocrine: ductless, must secrete right to capillaries
Classic hormone - correct answer Secreted into blood by group of modified epithelial cells
formed into glands, travel long distances to target, act at very low concentrations
Non-classic hormones - correct answer Secreted by neurons, immune cells, endocrine cells in
gut. Act more locally, diffuse through ECF (eg testosterone). Clearly ID'd as hormones in some
contexts, but also secreted in CNS as neurotransmitters
, Hormone action - correct answer Act via receptors (extracellular or in cytoplasm), cells can
increase/decrease sensitivity by changing receptor number and activity. Equilibrium between
free and bound hormone, need to drop blood concs to drop hormone activity.
Hormone half life - correct answer Inactivated on way through liver/kidney, which determines
halflife. Nonspecific ECF proteins also break down hormones
Ways to classify hormones - correct answer Source, mech of action (GPCR, RTKs, intracellular),
chemistry (a.a, peptide, steroid)
Protein/peptide hormones - correct answer Largest group. Range of size (3 a.as to
glycoprotein). Short halflife esp for smaller (seconds to minutes). Hydrophilic, synth+released
through secretory path. Primary transcript long pre-prohormone, processed lots until stored in
vesicles as prohormone. Released on signal. Act with GPCR/RTK/ion channel, usually rapid
effects (eg enzyme phosphorylation).
Amine hormones - correct answer Derived from tryptophan (melatonin) or tyrosine (thyroid
and catecholamines). Catecholamines (epi, norepi, dopa) are neurohormones, act via
membrane receptors. Thyroid hormones (T3, T4) are intracellular, have iodine molecules
incorporated
Steroids - correct answer Derived from cholesterol, only made in a few organs that express
sidechain cleavage enzyme (adrenal cortex, gonads, placenta). Small, lipophilic, synthesized on
demand by steroidogenic enzymes in smooth ER/inner mitochondrial membrane. Classic
receptors are in cytoplasm/nucleus
Steroid synthesis sites - correct answer Testosterone made in testes
Estradiol, progesterone made in ovaries
Cortisol, aldosterone made in adrenal cortex
Steroid mechanism of action - correct answer Diffuses through membrane, forms a complex
with receptor, imported to nucleus. Receptor-hormone complex then binds to DNA as a
transcription factor, activating/repressing gene expression. Slow.
Simple endocrine reflex (low Ca2+ eg) - correct answer Stimulus (low Ca2+) detected by
integrating center (parathyroid cell). Hormone (parathyroid) secreted in response. Hormone
travels through blood to target (bone and kidney), target responds (eg increasing Ca2+
reabsorption/resorption).
The integrating center both acts as the sensor and the hormone releaser
Complex neuroendocrine reflex - correct answer Stimulus detected by sensor, sensory neuron
carries information to integrating center. Then an efferent neuron or neurohormone carries
signal to endocrine integrating center, releases a hormone, etc.
