BRS PHYSIOLOGY: CHAPTER 7 EXAM QUESTIONS AND
ANSWERS WITH COMPLETE SOLUTIONS VERIFIED
All steroid hormones are derivatives of what common precursor?
Cholesterol
Thyroglublin is a derivative of...
Tyrosine
Epinephrine and norepinephrine are derivatives of...
Tyrosine
What are the two main determinants of the of a target tissue's responsiveness to
a particular hormone?
The number or sensitivity of receptors
G proteins are active when bound to...
GTP
G proteins are inactive when bound to...
GDP
Which subunit of G proteins binds GTP or GDP?
Alpha
Explain the responses to a hormone binding a Gs GPCR.
1. After hormone binding, GTP replaces GDP, activating the GPCR. The alpha subunit
activates adenylate cyclase.
,2. Adenylate cyclase catalyzes the formation of cAMP from ATP
3. cAMP activates protein kinase A
4. Protein kinase A phosphorylates proteins to carry out specific actions in the cell.
5. Phosphodiesterase degrades cAMP to 5'-AMP
What is the MOA of caffeine?
Caffeine inhibits phosphodiesterase, which normally degrades cAMP.
Inhibition of phosphodiesterase doesn't lead to the creation of more cAMP, but the
cAMP that was already present exhibits a longer half life in the presence of caffeine.
Explain the responses to a hormone binding a Gq GPCR.
1. After hormone binding, GTP displaces GDP, activating the GPCR. The alpha subunit
activates phospholipase C.
2. Phospholipase C catalyzes the formation of diacylglycerol (DAG) and IP3 from PIP2.
3. DAG activates protein kinase C, which phosphorylates proteins causing specific
actions in the cell.
4. IP3 increases calcium concentration inside the cell
Explain the calcium-calmodulin GPCR response.
, 1. Hormone binding receptor causes opening of calcium channels and release of
calcium from the ER. Overall, the intracellular calcium concentration is increased.
2. Calcium binds calmodulin, and the resultant complex carries out specific
physiological actions.
Explain the mechanism by which steroid and thyroid hormones alter gene
transcription.
1. Steroid or thyroid hormones diffuse across cell membranes and bind to receptors
(either intracellular or intranuclear)
2. Hormone receptor complex enters the nucleus (if not already located there) and
dimerizes.
3. Hormone-receptor dimer bind to steroid-response-elements (SREs) on DNA to initiate
DNA transcription.
4. New mRNA is produced, leaves the nucleus, and is translated to form new proteins.
5. New proteins have specific physiological actions.
What are the 6 major hormones of the anterior pituitary?
TSH, LH, FSH, ACTH, GH, Prolactin
Which anterior pituitary hormones are secreted by acidophils? Basophils?
ANSWERS WITH COMPLETE SOLUTIONS VERIFIED
All steroid hormones are derivatives of what common precursor?
Cholesterol
Thyroglublin is a derivative of...
Tyrosine
Epinephrine and norepinephrine are derivatives of...
Tyrosine
What are the two main determinants of the of a target tissue's responsiveness to
a particular hormone?
The number or sensitivity of receptors
G proteins are active when bound to...
GTP
G proteins are inactive when bound to...
GDP
Which subunit of G proteins binds GTP or GDP?
Alpha
Explain the responses to a hormone binding a Gs GPCR.
1. After hormone binding, GTP replaces GDP, activating the GPCR. The alpha subunit
activates adenylate cyclase.
,2. Adenylate cyclase catalyzes the formation of cAMP from ATP
3. cAMP activates protein kinase A
4. Protein kinase A phosphorylates proteins to carry out specific actions in the cell.
5. Phosphodiesterase degrades cAMP to 5'-AMP
What is the MOA of caffeine?
Caffeine inhibits phosphodiesterase, which normally degrades cAMP.
Inhibition of phosphodiesterase doesn't lead to the creation of more cAMP, but the
cAMP that was already present exhibits a longer half life in the presence of caffeine.
Explain the responses to a hormone binding a Gq GPCR.
1. After hormone binding, GTP displaces GDP, activating the GPCR. The alpha subunit
activates phospholipase C.
2. Phospholipase C catalyzes the formation of diacylglycerol (DAG) and IP3 from PIP2.
3. DAG activates protein kinase C, which phosphorylates proteins causing specific
actions in the cell.
4. IP3 increases calcium concentration inside the cell
Explain the calcium-calmodulin GPCR response.
, 1. Hormone binding receptor causes opening of calcium channels and release of
calcium from the ER. Overall, the intracellular calcium concentration is increased.
2. Calcium binds calmodulin, and the resultant complex carries out specific
physiological actions.
Explain the mechanism by which steroid and thyroid hormones alter gene
transcription.
1. Steroid or thyroid hormones diffuse across cell membranes and bind to receptors
(either intracellular or intranuclear)
2. Hormone receptor complex enters the nucleus (if not already located there) and
dimerizes.
3. Hormone-receptor dimer bind to steroid-response-elements (SREs) on DNA to initiate
DNA transcription.
4. New mRNA is produced, leaves the nucleus, and is translated to form new proteins.
5. New proteins have specific physiological actions.
What are the 6 major hormones of the anterior pituitary?
TSH, LH, FSH, ACTH, GH, Prolactin
Which anterior pituitary hormones are secreted by acidophils? Basophils?
