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Questions and Answers
What is an endocrine gland?
What is an endocrine gland?
What is an endocrine hormone?
What is an endocrine hormone?
A chemical substance produced by an endocrine gland and secreted directly into the blood.
Which of the following is an exocrine gland?
Which of the following is an exocrine gland?
What are target organ cells?
What are target organ cells?
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What is the role of a second messenger?
What is the role of a second messenger?
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What is autocrine signaling?
What is autocrine signaling?
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What characterizes endocrine signaling?
What characterizes endocrine signaling?
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What is a hormone?
What is a hormone?
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Which of the following is NOT a classification of hormones based on chemical structure?
Which of the following is NOT a classification of hormones based on chemical structure?
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What are steroids derived from?
What are steroids derived from?
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What is the function of steroid hormones?
What is the function of steroid hormones?
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What are proteins in the context of hormones?
What are proteins in the context of hormones?
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What do peptides include?
What do peptides include?
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Which hormones are considered glycoproteins?
Which hormones are considered glycoproteins?
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What are amines in the context of hormones?
What are amines in the context of hormones?
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What is epinephrine commonly known as?
What is epinephrine commonly known as?
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What is the primary role of dopamine?
What is the primary role of dopamine?
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What do thyroid hormones affect?
What do thyroid hormones affect?
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Where is the hypothalamus located?
Where is the hypothalamus located?
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Study Notes
Endocrine System Overview
- Endocrine glands are ductless and secrete hormones directly into the bloodstream, affecting target organs with specific receptors.
- Hormones are chemical substances released by endocrine glands into the blood that trigger specific responses in target tissues.
Gland Types
- Exocrine glands secrete products via ducts onto surfaces, unlike endocrine glands which release hormones into the bloodstream.
- Target organs/cells possess specific receptors to interact with hormones, antigens, antibodies, and other substances.
Signaling Mechanisms
- Autocrine signaling occurs when a cell secretes a hormone that binds to its own receptors, influencing its activity.
- Paracrine signaling involves hormones affecting nearby cells without entering the bloodstream, acting within local tissues.
- Endocrine signaling entails hormone release by endocrine cells to act on distant target cells.
Hormonal Structure Classification
- Hormones are classified into three chemical types: steroids, proteins, and amines, each with unique target tissues and mechanisms of action.
Steroid Hormones
- Steroids are derived from cholesterol, produced by adrenal glands, gonads, and placenta, and are lipid-soluble, circulating bound to carrier proteins.
- They exert effects by passing through the plasma membrane and binding to intracellular receptors, including sex hormones (estrogen, progesterone, testosterone) and adrenal hormones (aldosterone, cortisol).
Protein Hormones
- Protein hormones consist of 3-200 amino acid chains, are water-soluble, and released as needed without carrier proteins.
- Examples include peptides like insulin, glucagon, parathyroid hormone (PTH), human growth hormone (hGH), and prolactin (PRL).
Glycoprotein Hormones
- Glycoprotein hormones include follicle-stimulating hormone (FSH), luteinizing hormone (LH), thyroid-stimulating hormone (TSH), and human chorionic gonadotropin (hCG).
Amine Hormones
- Amines are derived from the amino acid tyrosine, encompassing catecholamines (epinephrine, norepinephrine, dopamine) and thyroid hormones (triiodothyronine [T3] and thyroxine [T4]).
Key Hormones and Functions
- Epinephrine (adrenaline) is a fight-or-flight hormone that prepares the body for emergencies.
- Dopamine is a neurohormone influencing behavior, cognition, and bodily functions, including inhibition of prolactin during lactation.
- Thyroid Hormones: T3 is the most potent, affecting metabolism, growth, and heart rate; T4 plays a role in metabolic processes and physical development.
Hypothalamus
- Located beneath the thalamus and above the brainstem, the hypothalamus is crucial in regulating various endocrine functions.
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Test your knowledge with these flashcards focused on the classification of hormones and the role of endocrine glands. Each card highlights key terms and definitions essential for understanding the endocrine system. Perfect for students learning about biology and human physiology.