Questions and Answers
How are the endocrine and nervous systems similar and different?
They both maintain homeostasis. However, the endocrine system has slow, long-term effects while the nervous system has fast, short-lived effects.
Why do cells communicate?
To coordinate activities and preserve homeostasis.
What are the four different mechanisms of cell communication?
Direct, paracrine, endocrine, and synaptic.
How are hormones categorized by chemical structure?
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What can happen to a hormone that is freely circulating through the bloodstream?
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How does binding with a carrier protein affect the stability of a hormone?
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How is specificity achieved in hormone response?
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What type of hormones would interact with a membrane receptor and what type would interact with an intracellular receptor?
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Why are second messengers sometimes necessary?
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How can target cell activity change in response to a hormone?
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What kinds of stimuli can cause an endocrine reflex to occur?
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What is the difference between a simple endocrine reflex and a complex endocrine reflex?
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In what three ways does the hypothalamus control the endocrine system?
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What is the relationship between the structure and function of the hypophyseal portal system?
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How do hypothalamic hormones regulate the activity of the anterior pituitary gland?
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Which seven hormones are secreted by the anterior pituitary gland?
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What is the function of TSH, and how is its secretion regulated?
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What is the function of ACTH, and how is its secretion regulated?
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What are the functions of FSH and LH, and how is the secretion of gonadotropins regulated?
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What is the function of PRL, and how is its secretion regulated?
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What is the function of GH, and how is its secretion regulated?
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What is the function of MSH?
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How is the structure of the hypothalamus integrated with the neurohypophysis?
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Study Notes
Endocrine and Nervous System
- Both systems maintain homeostasis.
- Endocrine system operates slowly with long-term effects; nervous system operates quickly with short-lived effects.
Purpose of Cell Communication
- Cells communicate to coordinate activities.
- Communication preserves homeostasis.
Mechanisms of Cell Communication
- Direct: Exchange across gap junctions, important in cardiac muscle contractions.
- Paracrine: Chemical signals communicate with adjacent cells, prevalent communication form.
- Endocrine: Hormones are released into the bloodstream to target specific cells.
- Synaptic: Involves neurotransmitters across synaptic clefts for rapid response.
Hormone Structure Categorization
- Hormones categorized into three types:
- Amino Acid Derivatives
- Peptide Hormones
- Lipid Derivatives
Hormone Circulation
- Freely circulating hormones are functional for less than an hour.
- They may diffuse out of the bloodstream or be broken down.
Carrier Proteins and Hormonal Stability
- Hormones bound to carrier proteins remain in the bloodstream longer, enhancing stability.
Specificity of Hormonal Response
- Specific target cell response is achieved through binding to specific carrier proteins.
Hormones and Receptors
- Membrane receptors are interacted with by certain hormones, while intracellular receptors respond to other hormone types.
Role of Second Messengers
- Second messengers amplify signals, modifying intracellular functions for enhanced communication.
Endocrine Reflex Stimuli
- Reflex can be triggered by three types of stimuli: humoral, hormonal, and neural.
Simple vs. Complex Endocrine Reflexes
- Simple reflex involves a single hormone; complex reflex entails multiple hormones and intermediary steps.
Hypothalamus and the Endocrine System
- Hypothalamus controls the endocrine system through:
- Production of ADH and oxytocin.
- Secretion of regulatory hormones influencing the anterior pituitary.
- Control of sympathetic output to adrenal medullae.
Hypophyseal Portal System
- Structure and function relate to the delivery of regulatory hormones from the hypothalamus to the anterior pituitary.
Hypothalamic Regulation of Anterior Pituitary
- Hypothalamic hormones stimulate or inhibit the synthesis and secretion of anterior pituitary hormones.
Anterior Pituitary Hormones
- Seven hormones secreted: TSH, ACTH, FSH, LH, prolactin, growth hormone, and melanocyte-stimulating hormone (MSH).
Functions and Regulation of TSH
- Function: Stimulates thyroid hormone release.
- Regulation: Triggered by TRH from the hypothalamus.
Functions and Regulation of ACTH
- Function: Stimulates glucocorticoid release from the adrenal cortex.
- Regulation: Released in response to CRH from the hypothalamus.
Functions and Regulation of FSH and LH
- FSH Function: Supports follicle development and sperm maturation.
- LH Function: Promotes ovulation and testosterone secretion.
- Regulation: Dependent on gonadal activity.
Functions and Regulation of Prolactin
- Function: Stimulates mammary gland development and milk production.
- Regulation: Stimulated by prolactin-releasing factors from the hypothalamus.
Functions and Regulation of Growth Hormone
- Function: Stimulates growth and somatomedin production.
- Regulation: Stimulated by GH-RH from the hypothalamus.
Function of MSH
- Function: Stimulates melanin production by melanocytes.
- Regulation: Release inhibited by dopamine.
Integration of Hypothalamus and Neurohypophysis
- The structural relationship facilitates hormone release from the posterior pituitary based on hypothalamic signals.
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Test your knowledge on the endocrine system with these flashcards. Gain insights into how the endocrine and nervous systems function, their similarities and differences, and the mechanisms of cell communication. Perfect for students looking to enhance their understanding of human biology.