Textbook Question
Some hormones act by:
a. Increasing the synthesis of enzymes
b. Converting an inactive enzyme into an active enzyme
c. Affecting only specific target organs
d. All of these
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Ch. 16 The Endocrine System
Marieb, Hoehn11th EditionHuman Anatomy & PhysiologyISBN: 9780136874034
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Table of contents
- Ch. 1 The Human Body: An Orientation24
- Ch. 2 Chemistry Comes Alive25
- Ch. 3 Cells: The Living Units21
- Ch. 4 Tissue: The Living Fabric20
- Ch. 5 The Integumentary System11
- Ch. 6 Bones and Skeletal Tissues19
- Ch. 7 The Skeleton14
- Ch. 8 Joints7
- Ch. 9 Muscles and Muscle Tissue26
- Ch. 10 The Muscular System26
- Ch. 11 Fundamentals of the Nervous System and Nervous Tissue19
- Ch. 12 The Central Nervous System26
- Ch. 13 The Peripheral Nervous System and Reflex Activity32
- Ch. 14 The Autonomic Nervous System19
- Ch. 15 The Special Senses26
- Ch. 16 The Endocrine System23
- Ch. 17 Blood25
- Ch. 18 The Cardiovascular System: The Heart24
- Ch. 19 The Cardiovascular System: Blood Vessels27
- Ch. 20 The Lymphatic System and Lymphoid Organs and Tissues14
- Ch. 21 The Immune System: Innate and Adaptive Body Defenses27
- Ch. 22 The Respiratory System21
- Ch. 23 The Digestive System31
- Ch. 24 Nutrition, Metabolism, and Energy Balance26
- Ch. 25 The Urinary System26
- Ch. 26 Fluid, Electrolyte, and Acid-Base Balance24
- Ch. 27 The Reproductive System24
- Ch. 28 Pregnancy and Human Development25
- Ch. 29 Heredity11
Marieb, Hoehn11th EditionHuman Anatomy & PhysiologyISBN: 9780136874034Not the one you use?Change textbook
Chapter 16, Problem 12
Absence of thyroid hormone would result in:
a. Increased heart rate and increased force of heart contraction
b. Depression of the CNS and lethargy
c. Exophthalmos
d. High metabolic rate
Verified step by step guidance1
Step 1: Understand the role of thyroid hormone in the body. Thyroid hormones primarily regulate metabolism, influence heart rate and force of contraction, and affect the central nervous system (CNS).
Step 2: Analyze the effects of thyroid hormone deficiency. When thyroid hormone is absent or low, metabolic rate decreases, leading to symptoms such as lethargy and depression of CNS activity.
Step 3: Evaluate each option in the context of thyroid hormone absence: (a) Increased heart rate and force of contraction would typically be caused by excess thyroid hormone, not its absence.
Step 4: Consider option (b) Depression of the CNS and lethargy, which aligns with the known effects of hypothyroidism (low thyroid hormone levels).
Step 5: Recognize that options (c) Exophthalmos and (d) High metabolic rate are associated with hyperthyroidism (excess thyroid hormone), so they are unlikely to result from absence of thyroid hormone.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Role of Thyroid Hormones in Metabolism
Thyroid hormones regulate the body's metabolic rate by controlling how cells use energy. Their absence typically leads to a decreased metabolic rate, causing symptoms like fatigue and weight gain, rather than an increased metabolic rate.
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Introduction to Metabolism
Effects of Thyroid Hormones on the Central Nervous System (CNS)
Thyroid hormones are essential for normal CNS function. A deficiency can cause CNS depression, resulting in lethargy, slowed mental processes, and reduced alertness, reflecting the hormone's role in maintaining brain activity.
Recommended video:
1:32The Central Nervous System
Cardiovascular Effects of Thyroid Hormones
Thyroid hormones increase heart rate and the force of heart contractions by enhancing sympathetic nervous system activity. Without these hormones, heart rate and contractility decrease, leading to slower circulation and reduced cardiac output.
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Related Practice
Textbook Question
If there is adequate carbohydrate intake, secretion of insulin results in:
a. Lower blood glucose levels
b. Increased cell utilization of glucose
c. Storage of glycogen
d. All of these
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Textbook Question
Describe the body location of each of the following endocrine organs: anterior pituitary, pineal gland, pancreas, ovaries, testes, and adrenal glands.
List the hormones produced by each organ.
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Textbook Question
Define hormone.
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Textbook Question
The anterior pituitary is often referred to as the master endocrine organ, but it, too, has a 'master.' What controls the release of anterior pituitary hormones?
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Textbook Question
Hormones
a. Are produced by exocrine glands
b. Are carried to all parts of the body in blood
c. Remain at constant concentration in the blood
d. Affect only non-hormone-producing organs