PHGY 216 MODULE 1 EXAM
QUESTIONS AND ANSWERS
What are the functions of the endocrine system? - Correct Answers -- maintain constant
internal environment via regulation of metabolism and H2O/electrolyte balance
- adaptive stress response
- growth and development
- reproduction
- red blood cell production
- integrating with the ANS in regulating both the circulation and digestive functions
What are hormones? - Correct Answers -hormones are chemical substances that are
secreted directly into the blood at low quantities and exert a physiological effect at a
distant target tissue
What are characteristics of hydrophilic hormones? - Correct Answers -- water loving
- highly water soluble and have low lipid solubility
- found unbound to carrier molecules within the plasma
- most are peptides or proteins
- amines are hormones based on single amino acid residues
What are examples of amine hormones? - Correct Answers -- catecholamines
(norepinephrine and epinephrine)
- catecholamines are found free and bound to carrier molecules
- thyroid hormones
- thyroid hormones are not hydrophilic
How are peptide hormones synthesized? - Correct Answers -synthesized and secreted
by the same cellular machinery that makes proteins within cells
How are peptide hormones synthesized in the synthesis phase? - Correct Answers -
large precursor proteins called preprohormones are synthesized by ER ribosomes into
prohormones
How are peptide hormones synthesized in the packaging phase? - Correct Answers -as
they travel through the ER and Golgi complex, these prohormones are processed into
active hormones and packaged into secretory vesicles
,How are peptide hormones synthesized in the storage phase? - Correct Answers -these
hormone containing secretory vesicles can be stored until the cell receives the
appropriate signal
How are peptide hormones synthesized in the secretion phase? - Correct Answers -the
appropriate signal initiates exocytosis if the vesicles and the hormones are released into
the blood
What are characteristics of lipophilic hormones? - Correct Answers -- lipid loving
- highly soluble in lipids and poorly soluble in water
- require a carrier molecule for transport throughout the body
What are examples of lipophilic hormones? - Correct Answers -- amine thyroid hormone
- steroid hormones
How are steroid hormones synthesized ? - Correct Answers -- all synthesized from
cholesterol
- which steroid hormone is produced by a particular tissue depends on the specific
enzymes within the cells of that tissue
- not stored
- they are secreted as they are synthesized
- to regulate the amount of steroid hormone released, you need to regulate its synthesis
Where is cortisol made? - Correct Answers -adrenal cortex
Which hormones are dissolved in plasma? - Correct Answers -peptide hormones are
able to freely dissolve in plasma
Which hormones are found bound to carrier molecules or proteins? - Correct Answers -
steroid and thyroid hormones bind to specific carrier molecules or to plasma proteins
such as albumin
Which hormones are dissolved in plasma or bound to carrier molecules or proteins? -
Correct Answers -catecholamines are unique as 50% are found free in the plasma and
50% bind to albumin, they are water soluble
How do hormones interact with their target cells? - Correct Answers -- only free,
unbound hormones can interact with a receptor at its target cell
- not an issue for hydrophilic hormones and catecholamines
What is the dynamic equilibrium of lipophilic hormones binding to its carrier? - Correct
Answers -- at a given time, not 100% of a steroid hormone in the blood is bound to its
carrier molecule
- instead, the hormones are dynamically unbinding and rebinding which results in a
small fraction of hormone that is unbound at any given time
- this unbound hormone is active and able to act on target cells
, How do lipophilic hormones interact with their target cells? - Correct Answers -dynamic
equilibrium
Where are the receptors for hydrophilic hormones? - Correct Answers -- peptide
hormones and catecholamines bind to specific receptors on the outer surface of the
plasma of their target cells
- they are unable to freely cross the lipid bilayer of the plasma membrane
Where are the receptors for lipophilic hormones? - Correct Answers -steroid hormones
and thyroid hormones can easily slip through the plasma membrane and bind to specific
receptors inside their target cells
What happens after peptide hormones or catecholamines bind to its receptor? - Correct
Answers -- binding of these hormones to their surface receptors produces effects within
cells by activating second messenger systems
- these pathways are able to amplify the initial signal as low concentrations of hormones
trigger large cellular responses
How does cAMP act as a secondary messenger? - Correct Answers -- an extracellular
messenger binds to a receptor, activating a G protein which shuttles to and activates
several adenylyl cyclase molecules
- these activated proteins convert many molecules of ATP to cAMP which then activate
protein kinase A
- the activated protein kinase A enzymes then phosphorylate and activate target
proteins which can bring about the desired result
How does calcium act as a secondary messenger? - Correct Answers -- an extracellular
messenger binds to a receptor activating a G protein, which shuttles to activate several
phospholipase C enzymes
- these proteins convert PIP2 to IP3 and DAG
- IP3 mobilizes intracellular Ca2+ which activates calmodulin
- the Ca2+-calmodulin complexes then activate Ca2+-calmodulin-dependent protein
kinase (CaM kinase), which phosphorylate and activate target proteins, bringing about
the desired response
How to lipophilic hormones exert their effects on cells? - Correct Answers -regulating
protein synthesis
Where can lipophilic hormone receptors be found? - Correct Answers -within the
cytoplasm or the nucleus
What are the steps that lipophilic hormones regulate protein synthesis? - Correct
Answers -- free lipophilic hormone diffuse across the plasma membrane and/or the
nuclear membrane to interact with intracellular receptors
QUESTIONS AND ANSWERS
What are the functions of the endocrine system? - Correct Answers -- maintain constant
internal environment via regulation of metabolism and H2O/electrolyte balance
- adaptive stress response
- growth and development
- reproduction
- red blood cell production
- integrating with the ANS in regulating both the circulation and digestive functions
What are hormones? - Correct Answers -hormones are chemical substances that are
secreted directly into the blood at low quantities and exert a physiological effect at a
distant target tissue
What are characteristics of hydrophilic hormones? - Correct Answers -- water loving
- highly water soluble and have low lipid solubility
- found unbound to carrier molecules within the plasma
- most are peptides or proteins
- amines are hormones based on single amino acid residues
What are examples of amine hormones? - Correct Answers -- catecholamines
(norepinephrine and epinephrine)
- catecholamines are found free and bound to carrier molecules
- thyroid hormones
- thyroid hormones are not hydrophilic
How are peptide hormones synthesized? - Correct Answers -synthesized and secreted
by the same cellular machinery that makes proteins within cells
How are peptide hormones synthesized in the synthesis phase? - Correct Answers -
large precursor proteins called preprohormones are synthesized by ER ribosomes into
prohormones
How are peptide hormones synthesized in the packaging phase? - Correct Answers -as
they travel through the ER and Golgi complex, these prohormones are processed into
active hormones and packaged into secretory vesicles
,How are peptide hormones synthesized in the storage phase? - Correct Answers -these
hormone containing secretory vesicles can be stored until the cell receives the
appropriate signal
How are peptide hormones synthesized in the secretion phase? - Correct Answers -the
appropriate signal initiates exocytosis if the vesicles and the hormones are released into
the blood
What are characteristics of lipophilic hormones? - Correct Answers -- lipid loving
- highly soluble in lipids and poorly soluble in water
- require a carrier molecule for transport throughout the body
What are examples of lipophilic hormones? - Correct Answers -- amine thyroid hormone
- steroid hormones
How are steroid hormones synthesized ? - Correct Answers -- all synthesized from
cholesterol
- which steroid hormone is produced by a particular tissue depends on the specific
enzymes within the cells of that tissue
- not stored
- they are secreted as they are synthesized
- to regulate the amount of steroid hormone released, you need to regulate its synthesis
Where is cortisol made? - Correct Answers -adrenal cortex
Which hormones are dissolved in plasma? - Correct Answers -peptide hormones are
able to freely dissolve in plasma
Which hormones are found bound to carrier molecules or proteins? - Correct Answers -
steroid and thyroid hormones bind to specific carrier molecules or to plasma proteins
such as albumin
Which hormones are dissolved in plasma or bound to carrier molecules or proteins? -
Correct Answers -catecholamines are unique as 50% are found free in the plasma and
50% bind to albumin, they are water soluble
How do hormones interact with their target cells? - Correct Answers -- only free,
unbound hormones can interact with a receptor at its target cell
- not an issue for hydrophilic hormones and catecholamines
What is the dynamic equilibrium of lipophilic hormones binding to its carrier? - Correct
Answers -- at a given time, not 100% of a steroid hormone in the blood is bound to its
carrier molecule
- instead, the hormones are dynamically unbinding and rebinding which results in a
small fraction of hormone that is unbound at any given time
- this unbound hormone is active and able to act on target cells
, How do lipophilic hormones interact with their target cells? - Correct Answers -dynamic
equilibrium
Where are the receptors for hydrophilic hormones? - Correct Answers -- peptide
hormones and catecholamines bind to specific receptors on the outer surface of the
plasma of their target cells
- they are unable to freely cross the lipid bilayer of the plasma membrane
Where are the receptors for lipophilic hormones? - Correct Answers -steroid hormones
and thyroid hormones can easily slip through the plasma membrane and bind to specific
receptors inside their target cells
What happens after peptide hormones or catecholamines bind to its receptor? - Correct
Answers -- binding of these hormones to their surface receptors produces effects within
cells by activating second messenger systems
- these pathways are able to amplify the initial signal as low concentrations of hormones
trigger large cellular responses
How does cAMP act as a secondary messenger? - Correct Answers -- an extracellular
messenger binds to a receptor, activating a G protein which shuttles to and activates
several adenylyl cyclase molecules
- these activated proteins convert many molecules of ATP to cAMP which then activate
protein kinase A
- the activated protein kinase A enzymes then phosphorylate and activate target
proteins which can bring about the desired result
How does calcium act as a secondary messenger? - Correct Answers -- an extracellular
messenger binds to a receptor activating a G protein, which shuttles to activate several
phospholipase C enzymes
- these proteins convert PIP2 to IP3 and DAG
- IP3 mobilizes intracellular Ca2+ which activates calmodulin
- the Ca2+-calmodulin complexes then activate Ca2+-calmodulin-dependent protein
kinase (CaM kinase), which phosphorylate and activate target proteins, bringing about
the desired response
How to lipophilic hormones exert their effects on cells? - Correct Answers -regulating
protein synthesis
Where can lipophilic hormone receptors be found? - Correct Answers -within the
cytoplasm or the nucleus
What are the steps that lipophilic hormones regulate protein synthesis? - Correct
Answers -- free lipophilic hormone diffuse across the plasma membrane and/or the
nuclear membrane to interact with intracellular receptors
