Ch 10 Hormone Signaling Flashcards
What are hormone-secreting endocrine cells?
Hormone-secreting endocrine cells may occur in regions of the brain (hypothalamus, pituitary glands) or other regions such as adrenal glands, gonads, thyroid
What is the role of the endocrine system?
The endocrine system regulates metabolic pathways through chemical signals sent between organs and cells
Define hormone.
A chemical messenger produced in the ductless glands of the endocrine system, transported by the bloodstream from the site of synthesis to the site(s) of action
What are the roles of hormones?
- Maintenance of homeostasis
- Regulation of growth and development
What is homeostasis?
A balance of biological activities in an organism
What is the basic structure of steroid hormones?
Steroids are synthesized from cholesterol and possess a basic four-ring structure
How do most hormones induce a response in target cells?
Most hormones bind to specific receptors located at the surface of target cells
What is the most common second messenger in hormone signaling?
Cyclic AMP (cAMP)
Give an example of an amino acid derivative hormone and its function.
Epinephrine (adrenalin): stimulates heart rate and glycogen breakdown
What is the function of insulin?
Stimulates glucose uptake from the blood and glycogen synthesis
What is negative feedback in hormonal control?
When the output of a pathway inhibits inputs to the pathway
What do G protein coupled receptors (GPCRs) do?
Bind guanine nucleotides (GTP and GDP) and mediate signal transduction
What is the function of phosphodiesterase in cellular signaling?
Turns off cAMP-dependent signaling by hydrolyzing cAMP to AMP
True or False: β-blockers antagonize epinephrine and norepinephrine.
True
What happens after cAMP is produced?
Cyclic AMP activates a cAMP-dependent protein kinase
What is the role of protein kinase A?
Phosphorylates target enzymes to induce a cellular response
What does the binding of hormone to its receptor trigger?
A cascade of reactions by which second messengers elicit the actual cellular response
Fill in the blank: The two important second messengers in hormonal signaling are _______ and _______.
cAMP, PIP2
What does insulin primarily stimulate?
The glucose transporters in muscles, particularly the GLUT4 transporter
What is the effect of elevated insulin levels related to?
Alzheimer’s disease
What are the two types of subunits in the insulin receptor?
- α
- β
What is the role of calcium ions in PIP2 signaling?
Intimately involved in the action of PIP2
What is the effect of epinephrine on glycogen metabolism?
Inhibits glycogen synthesis and stimulates glycogen breakdown to glucose
How is adenylate cyclase activated?
By the dissociation of the alpha subunit of G protein binding to it
