Textbook Question
Decreased blood calcium level would result in increased:
(a) Secretion of calcitonin
(b) Secretion of PTH
(c) Elimination of calcium by the kidneys
(d) Osteoclast activity
(e) Excitability of neural membranes
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Ch. 18 The Endocrine System
Martini, Nath, Bartholomew11th EditionFundamentals of Anatomy & PhysiologyISBN: 9780136874089
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Table of contents
- Ch. 1 An Introduction to Anatomy and Physiology26
- Ch. 2 The Chemical Level of Organization34
- Ch. 3 The Cellular Level of Organization30
- Ch. 4 The Tissue Level of Organization24
- Ch. 5 The Integumentary System17
- Ch. 6 Bones and Bone Structure36
- Ch. 7 The Axial Skeleton11
- Ch. 8 The Appendicular Skeleton17
- Ch. 9 Joints13
- Ch. 10 Muscle Tissue12
- Ch. 11 The Muscular System28
- Ch. 12 Nervous Tissue18
- Ch. 13 The Spinal Cord, Spinal Nerves, and Spinal Reflexes22
- Ch. 14 The Brain and Cranial Nerves20
- Ch. 15 Sensory Pathways and the Somatic Nervous System17
- Ch. 16 The Autonomic Nervous System and Higher-Order Functions30
- Ch. 17 The Special Senses16
- Ch. 18 The Endocrine System20
- Ch. 19 Blood31
- Ch. 20 The Heart31
- Ch. 21 Blood Vessels and Circulation29
- Ch. 22 The Lymphatic System and Immunity31
- Ch. 23 The Respiratory System12
- Ch. 24 The Digestive System18
- Ch. 26 The Urinary System31
- Ch. 27 Fluids & Electrolytes32
- Ch. 28 The Reproductive System12
- Ch. 29 Development and Inheritance23
Martini, Nath, Bartholomew11th EditionFundamentals of Anatomy & PhysiologyISBN: 9780136874089Not the one you use?Change textbook
Chapter 18, Problem 20
How would blocking the activity of phosphodiesterase (PDE) affect a cell that responds to hormonal stimulation by the cAMP second messenger system?
Verified step by step guidance1
Step 1: Understand the role of phosphodiesterase (PDE) in the cAMP second messenger system. PDE is an enzyme that breaks down cyclic AMP (cAMP) into AMP, thereby reducing the intracellular concentration of cAMP and terminating the signal.
Step 2: Recall that cAMP acts as a second messenger that activates protein kinase A (PKA), which then phosphorylates target proteins to elicit a cellular response to hormonal stimulation.
Step 3: Consider what happens if PDE activity is blocked. Since PDE normally degrades cAMP, blocking PDE will prevent cAMP breakdown, leading to an accumulation of cAMP inside the cell.
Step 4: Analyze the consequence of increased cAMP levels. Elevated cAMP will prolong and amplify the activation of PKA, resulting in a stronger and longer-lasting cellular response to the hormone.
Step 5: Summarize that blocking PDE enhances the hormonal signal by maintaining higher cAMP levels, which sustains the activation of downstream signaling pathways and cellular effects.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Phosphodiesterase (PDE) Function
Phosphodiesterase enzymes break down cyclic AMP (cAMP) into AMP, terminating the cAMP signaling. By degrading cAMP, PDE regulates the intensity and duration of the signal inside the cell, ensuring that the response to hormonal stimulation is properly controlled.
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Functional Groups
cAMP Second Messenger System
The cAMP second messenger system transduces extracellular hormonal signals into intracellular actions. When a hormone binds to its receptor, it activates adenylate cyclase to produce cAMP, which then activates protein kinase A (PKA) to trigger downstream cellular responses.
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10:41Secondary Messengers
Effect of PDE Inhibition on Cellular Signaling
Blocking PDE activity prevents cAMP breakdown, leading to elevated and prolonged cAMP levels. This enhances and extends the hormonal signal, potentially amplifying cellular responses such as enzyme activation, gene expression, or metabolic changes.
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Related Practice
Textbook Question
What are the four opposing effects of natriuretic peptides and angiotensin II?
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Textbook Question
In what ways can a hormone modify the activities of its target cells?
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Textbook Question
A researcher observes that stimulation by a particular hormone induces a marked increase in the activity of G proteins in the target plasma membrane. The hormone being studied is probably:
(a) A steroid
(b) A peptide
(c) Testosterone
(d) Estrogen
(e) Aldosterone
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Textbook Question
What is the primary difference in the way the nervous and endocrine systems communicate with their target cells?
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Textbook Question
In Type 2 diabetes, insulin levels are frequently normal, yet the target cells are less sensitive to the effects of insulin. This suggests that the target cells:
(a) Are impermeable to insulin
(b) May lack enough insulin receptors
(c) Cannot convert insulin to an active form
(d) Have adequate internal supplies of glucose
(e) Both b and c
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