Endocrine 1
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Questions and Answers

Which of the following is NOT considered a major endocrine gland?

  • Thymus gland (correct)
  • Pituitary gland
  • Thyroid gland
  • Pancreas

What is the primary way endocrine hormones reach their target cells?

  • By direct contact with adjacent cells
  • Via the lymphatic system
  • Through the bloodstream (correct)
  • Through ducts

What is the meaning of the Greek word 'Hormao' which is the root of the word 'hormone'?

  • To transport
  • To excite or stir up (correct)
  • To inhibit
  • To neutralize

Which of the following best describes an exocrine gland?

<p>Secretes substances through a duct to reach its target (B)</p> Signup and view all the answers

Which of the following hormones is derived from cholesterol?

<p>Steroid hormones (D)</p> Signup and view all the answers

Which of the following is an example of a protein and peptide hormone?

<p>Insulin (D)</p> Signup and view all the answers

From what amino acid are hormones such as epinephrine and thyroxine derived?

<p>Tyrosine (C)</p> Signup and view all the answers

Which of these organs does NOT contain endocrine cells?

<p>Lungs (B)</p> Signup and view all the answers

What does the term 'target cell' refer to in the context of hormone action?

<p>A cell that expresses receptors for a specific hormone (C)</p> Signup and view all the answers

Why are hydrophobic hormones able to enter cells, while hydrophilic hormones cannot?

<p>Hydrophobic hormones have a higher affinity for cell membranes, which are composed of lipids. (D)</p> Signup and view all the answers

What is the primary role of the binding domain in a hormone receptor?

<p>To recognize and bind to a specific hormone (A)</p> Signup and view all the answers

What kind of intracellular signaling pathways are activated by G-protein linked receptors?

<p>Phosphorylation cascades involving serine/threonine kinases (A)</p> Signup and view all the answers

Which of the following is NOT a characteristic of hormone receptors?

<p>They are always located on the outer surface of the cell membrane. (C)</p> Signup and view all the answers

What is the primary function of the signal transducing domain in a hormone receptor?

<p>To activate specific enzymes that carry out cellular responses (D)</p> Signup and view all the answers

What is the main difference between G-protein linked receptors and receptors with inherent tyrosine kinase activity?

<p>The mechanism of signal transduction (B)</p> Signup and view all the answers

How do hormones promote cellular responses?

<p>By binding to specific receptors on target cells and initiating intracellular signaling (C)</p> Signup and view all the answers

Which characteristic is NOT typically associated with steroid hormones?

<p>Acting via membrane bound receptors (C)</p> Signup and view all the answers

What is the primary precursor for the synthesis of thyroid hormones and epinephrine?

<p>Tyrosine (D)</p> Signup and view all the answers

Which of the following hormones is derived from Tryptophan?

<p>Serotonin (C)</p> Signup and view all the answers

Epinephrine and Norepinephrine are commonly derived from which amino acid?

<p>Tyrosine (C)</p> Signup and view all the answers

Which of the following characteristics is typical of a peptide hormone?

<p>Water soluble (A)</p> Signup and view all the answers

What is the immediate precursor for steroid hormones?

<p>Cholesterol (B)</p> Signup and view all the answers

During the synthesis of a protein hormone, what is the role of mRNA?

<p>To be translated into an amino acid sequence (B)</p> Signup and view all the answers

Which of these are a class of hormones derived from amino acids?

<p>Tyrosine derivatives (C)</p> Signup and view all the answers

What is the primary mechanism through which steroid hormones exert their effects?

<p>Interaction with cytoplasmic or nuclear receptors (A)</p> Signup and view all the answers

What structural components make up the insulin receptor?

<p>Two alpha subunits and two beta subunits (B)</p> Signup and view all the answers

How does insulin binding to its receptor affect intracellular processes?

<p>Promotes receptor phosphorylation and activation (B)</p> Signup and view all the answers

What role do transcription factors play in cellular response to steroid hormones?

<p>Activate gene expression for protein synthesis (C)</p> Signup and view all the answers

What determines the specificity of hormone responses in target cells?

<p>Receptor types and second messenger activation (A)</p> Signup and view all the answers

What is a common outcome of activating the insulin receptor?

<p>Increased expression of glucose transporter (GLUT4) (B)</p> Signup and view all the answers

In which phase of hormone action does receptor dimerization occur for steroid hormones?

<p>After receptor activation (B)</p> Signup and view all the answers

What happens when a steroid hormone binds to its receptor?

<p>Activation of gene transcription and protein synthesis (B)</p> Signup and view all the answers

What is one key function of cortisol in response to stress?

<p>Increases metabolism of proteins, fats, and carbohydrates (D)</p> Signup and view all the answers

How does cortisol primarily maintain glucose levels in the body?

<p>By promoting gluconeogenesis (C)</p> Signup and view all the answers

Which of the following levels of hormone action is involved in regulating metabolism?

<p>Whole body level (C)</p> Signup and view all the answers

What is the priming effect in the context of hormone action?

<p>Induction of more receptors in target cells (D)</p> Signup and view all the answers

What occurs during desensitization in hormone action?

<p>Constant exposure to a hormone decreases cell response (B)</p> Signup and view all the answers

At which level do hormones regulate gene transcription and enzyme activity?

<p>Molecular level (C)</p> Signup and view all the answers

Which of the following is NOT a documented function of cortisol?

<p>Promotion of rapid cell division (C)</p> Signup and view all the answers

What is a result of constant exposure to a hormone?

<p>Receptor endocytosis and decreased response (C)</p> Signup and view all the answers

Flashcards

Endocrinology

The study of hormones and their effects on the body.

Reproductive Biology

The study of the reproductive system and its functions.

Homeostasis

The maintenance of a stable internal environment in the body despite external changes.

Identify Anatomical Components

The ability to identify and differentiate between the major structures of the endocrine and reproductive systems.

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Understand Physiological Functions

The ability to explain how the endocrine and reproductive systems function normally.

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Endocrine Glands

Ductless glands that secrete hormones directly into the bloodstream.

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Exocrine Glands

Glands that secrete substances through ducts to target organs or tissues.

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Hormones

Chemical messengers produced by specialized cells in endocrine glands or tissues.

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Peptide Hormones

Hormones derived from amino acids, including insulin and epinephrine.

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Steroid Hormones

Lipid-based hormones synthesized from cholesterol, including testosterone and estrogen.

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Tyrosine Derivative Hormones

Hormones derived from the amino acid tyrosine, including thyroid hormone and epinephrine.

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Target Cells

Cells that respond to a specific hormone.

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Hormonal Signaling

The process by which a hormone interacts with its specific target cell, triggering a change in the cell's activity.

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Amino Acid-Based Hormones

Hormones produced from amino acids. They are water-soluble (hydrophilic) and bind to receptors on the cell surface.

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Transcription

The process of converting DNA into RNA.

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Translation

The process of converting RNA into a protein.

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Feedback Loop Regulation

A mechanism that regulates hormone production and release. It involves negative feedback loops, where the product of a pathway inhibits further production.

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Releasing Hormones

Hormones that stimulate the release of other hormones from the anterior pituitary.

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Hormone Specificity

The ability of a hormone to bind to specific receptors on target cells, leading to a specific cellular response.

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Mechanism of Action

The biochemical events that occur within a cell in response to hormone binding, ultimately leading to a specific cellular response.

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What determines a cell's response to a hormone?

Hormones travel throughout the body but only affect cells with specific receptors. These cells are known as target cells.

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Where are hormone receptors located?

Hormones can bind to receptors located on the cell membrane or inside the cell.

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How do water-soluble hormones work?

Hormones that are water-soluble (like proteins and peptides) bind to receptors on the cell membrane. These receptors, in turn, activate signaling pathways inside the cell.

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How do lipid-soluble hormones work?

Hormones that are lipid-soluble (like steroids and thyroid hormones) can pass directly through the cell membrane and bind to receptors inside the cell. These receptors often act as transcription factors, influencing gene expression.

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What is the role of G-protein coupled receptors?

G-protein coupled receptors activate intracellular signaling pathways using second messengers like cAMP, diacylglycerol, and calmodulin. These second messengers relay the hormonal signal, often amplifying it.

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How do tyrosine kinase receptors work?

Receptors with inherent tyrosine kinase activity or associated with tyrosine kinase activity directly activate intracellular signaling pathways. These pathways often involve phosphorylation of proteins, altering their function.

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What is the result of hormone-receptor binding?

Hormones trigger complex intracellular signaling pathways that ultimately lead to specific cellular responses.

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Why is hormone inactivation important?

Hormone inactivation and clearance mechanisms regulate the duration and intensity of hormone signaling. This ensures proper hormone homeostasis and prevents excessive signaling.

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Signal Transduction

A type of cell signaling where the signal is transmitted through a series of intracellular molecules, often involving protein phosphorylation.

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Tyrosine Kinase Receptor

A transmembrane receptor that, upon binding its ligand, activates its intrinsic kinase activity to phosphorylate downstream signaling molecules.

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Genomic Action

The process by which a hormone triggers gene expression, leading to the synthesis of new proteins and ultimately cellular responses.

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Transcription Factor

A specialized protein that binds to a specific DNA sequence to regulate gene expression.

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Dimerization

The formation of a complex between two or more molecules, often involving a binding event between a ligand and its receptor.

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Phosphorylation

The process of adding a phosphate group to a molecule, often a protein, by a kinase enzyme.

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Differential Hormone Response

Different cell types can respond to the same hormone in different ways, due to variations in receptor types and intracellular signaling pathways.

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Cortisol's role in energy metabolism

The stress hormone, cortisol, stimulates increased metabolism of proteins, fats, and carbohydrates to maintain blood glucose levels.

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Cortisol's immune suppression

Cortisol has anti-inflammatory effects, helping to suppress the immune system.

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Priming effect

The priming effect occurs when a hormone increases its own receptors, enhancing the target cell's response.

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Desensitization

Constant hormone exposure can lead to desensitization. The target cell reduces its receptors, attenuating the signal.

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Hormonal actions at the molecular level

Hormone actions occur at the molecular level, affecting gene expression, protein synthesis, enzyme activity, and protein interactions.

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Hormonal effects at the cellular level

Hormones regulate various aspects of a cell's functioning, including division, differentiation, death, motility, secretion, and nutrient uptake.

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Hormonal regulation at the whole-body level

Hormones regulate whole-body functions like ion and fluid balance, energy metabolism, environmental adaptation, growth, and reproduction.

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Hormone response variation

A hormone's effect can depend on the level of stimulation, with the priming effect increasing response and desensitization decreasing it.

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Study Notes

Course Information

  • Course title: VETM 5194, Endocrine and Reproductive Systems I: The Healthy Animal
  • Instructor: Maria M. Viveiros, [email protected]
  • Course dates: January 23 – February 21, 2025 (Spring 2025)

Class Schedule

  • Schedule details are available on eLC
  • Specific dates and times are provided for lectures, exams, and clinical skills sessions,
  • Schedule includes details for the Endocrine System and Reproductive System, including assigned labs

Assessments

  • Endocrine System:
    • Course Activities (10%): Include in-class, lab, integrative session, online, and take-home activities/assignments.
    • Quiz #1: 15% (January 29, 1 pm)
    • Exam #1: 25% (February 3, 10 am)
  • Reproductive System:
    • Course Activities (10%): Same as above.
    • Quiz #2: 15% (February 12, 1 pm)
    • Exam #2 (written): 15%; (Anatomy: 10%); (February 23, 10am)

Learning Objectives

  • Identify the major components (gross & microscopic) of endocrine and reproductive systems
  • Understand and describe the major physiological functions of endocrine and reproductive systems in the healthy animal.
  • Recognize and discuss how different organ systems interact leading to integrated physiological responses that maintain homeostasis.
  • Apply knowledge of normal endocrine and reproductive function to identify examples of disruptions that can lead to disease.

The Endocrine System

  • Diagram shows location of major glands in an animal and their names.
  • Regulates hormone secretion from glands & tissues
  • Hormone action on target cells and organs functions
  • Physiological issues due to endocrine disruption (e.g., diabetes, hyper-/hypothyroidism)
  • Types of glands: Exocrine and endocrine
  • Glands are specialized key glands (e.g., Pituitary, Parathyroid, Thyroid, Adrenal, Pancreas, Ovaries, Testes)

Endocrine Function

  • Hormone action on target cells/tissues regulates essential physiological processes: -Growth and development -Cellular metabolism and energy balance -Response to stress -Maintenance of electrolyte, water and nutrient balance. -Reproduction

Learning Objectives (Endocrine System)

  • Understanding hormone secretion from endocrine glands and tissues
  • Hormone action on target cells/organs functions is defined.
  • Physiopathology is described, and it includes inappropriate hormone levels
  • Disrupted target cell response to hormones is discussed

Hormone Classification

  • Types and classifications of hormones are detailed:
    • Proteins(>20aa): Examples include Insulin, Glucagon, ACTH, FSH, TSH, LH, Prolactin, Growth Hormone, Calcitonin, Corticotrophin releasing hormone, Growth Hormone releasing hormone
    • Peptides(<20aa): Examples include Oxytocin, Vasopressin, Angiotensin, MSH, Somatostatin, Thyrotrophin-RH, Gonadotrophin-RH
    • Steroids: Examples include Estradiol, Testosterone, Progesterone, Cortisol, Aldosterone
    • Tyrosine derivatives: Examples include Triiodothyronine (T3), Thyroxine (T4), Epinephrine, Norepinephrine, Dopamine.

Basic Features of Hormones

  • Synthesis and secretion
  • Transport in the circulation & plasma concentrations.
  • Feedback loop regulation
  • Specificity and Mechanism of action on target cells.
  • Hormone receptor types (Cell surface, Intracellular)
  • Action on target cells

Hormone Receptors

  • Hormone receptors are proteins
  • Receptors have binding domain & signal transduction domain
  • Recognize and bind specific hormones, and each hormone binds to a a unique receptor.
  • Receptors undergo conformational change (shape-change) when hormones bind.
  • Signal transduction (relaying a message) results in a cellular response.

Mechanisms of Protein Hormones and Steroid Hormones

  • G-protein linked receptors cause activation of serine/threonine kinases, such as cAMP and others
  • Tyrosine kinase receptors activate existing proteins or elicit production of new proteins through activating transcription factors.
  • Steroid hormones interact with cytoplasmic or nuclear receptors
  • A hormone binding with a receptor can initiate a cascade of events, in turn, promoting gene expression
  • New proteins are created to manage cellular responses

Hormone Receptor Types

  • Membrane-bound receptors (hydrophilic hormones): Do not enter the cell, rather, hormones bind to receptors on the cell membrane, resulting in downstream effects.
  • Intracellular receptors (hydrophobic hormones): Lipid soluble hormones enter the cell and bind with receptors inside the cell. This binding typically leads to changes in gene expression.

Hormone Clearance and Excretion

  • Clearance is the rate of hormone disappearance from plasma
  • Most peptide hormones have a short half-life (minutes to hours) and are metabolized rapidly
  • Steroid or thyroid hormones have a long half-life (days to weeks).
  • Hormone excretion (elimination) is through the kidneys, bile and other pathways in the body.

Endocrine Disruption

  • Hormone excess (hyperfunction): Due to gland hyperplasia, hormone-producing tumors, or excessive stimulation
  • Hormone deficiency (hypofunction): Due to congenital defects, destruction of endocrine tissue (e.g., ischemia, inflammation, autoimmune responses), inactive hormones, or destruction due to antibodies.
  • Altered responsiveness of receptors: Can be due to reduced or no receptor expression, defects in receptor structure, lack of receptor down-regulation or constitutive receptor activation

Hormone Secretion Rhythms

  • Daily circadian rhythms (day/night): Example: cortisol, Growth Hormone(GH), melatonin
  • Monthly or seasonal rhythms: Example: gonadotropins
  • Developmental rhythms: Example: puberty, menopause

Summary

  • The same hormone can promote different responses in different target cell types.
  • Specificity is controlled by receptor and second messenger activation within the cell.
  • Various examples of endocrine responses are presented.

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Description

Test your knowledge on the Endocrine System with this quiz. Explore various aspects including assessment components, hormone functions, and gland characteristics. This quiz will help reinforce your understanding of key concepts related to endocrine glands and hormones.

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