Endocrinology Lecture 1 Quiz

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Questions and Answers

What is the main role of thyroid hormone (TH) in the body?

Enhancing immune function

Controlling metabolism and heat production (correct)

Regulating blood sugar levels

Stimulating growth in muscle

Thyrotropin-releasing hormone (TRH) is released from the anterior pituitary.

False

What are the two main types of thyroid hormone mentioned in the content?

T3 and T4

Thyroid hormone is primarily made in the ______ gland.

thyroid Signup and view all the answers

Match the hormones with their functions:

Growth Hormone = Promotes growth and development Thyroid-Stimulating Hormone (TSH) = Stimulates the thyroid gland Thyrotropin-Releasing Hormone (TRH) = Stimulates the release of TSH Thyroid Hormone (TH) = Controls metabolic rate Signup and view all the answers

What is a key function of the endocrine system?

Integrating functions across multiple physiological systems Signup and view all the answers

Hydrophilic hormones can pass through cell membranes easily.

False Signup and view all the answers

Name one type of hormone that is classified as a peptide.

Insulin Signup and view all the answers

The two control pathways of hormone secretion are regulation and regulation.

central, direct Signup and view all the answers

Match the following hormones with their classifications:

ADH = Peptide Adrenaline = Amine Cortisol = Steroid Thyroid hormones = Lipophilic Signup and view all the answers

Which of the following hormones is lipophilic?

Cortisol Signup and view all the answers

Direct regulation of hormone activity responds quickly to changes in plasma levels of substances.

True Signup and view all the answers

What role does the thyroid gland play in metabolism?

It synthesizes thyroid hormones that regulate metabolism. Signup and view all the answers

Which type of hormone can diffuse across the plasma membrane?

Lipophilic hormones Signup and view all the answers

Thyroid hormones primarily increase the body's metabolic rate.

True Signup and view all the answers

What does BMR stand for?

Basal Metabolic Rate Signup and view all the answers

Thyroid hormones T3 and T4 are produced from ________ and iodine.

tyrosine Signup and view all the answers

Match the following components with their respective functions:

Follicular cells = Produce thyroid hormones Colloid = Storage of thyroid hormones Thyroid hormones T3 = Regulate metabolism Thyroid hormones T4 = More abundant but less potent Signup and view all the answers

Which hormone is more potent?

T3 Signup and view all the answers

Metabolic rate refers solely to energy used at rest.

False Signup and view all the answers

What effect do thyroid hormones have on heart responsiveness?

Increases heart responsiveness to adrenaline and noradrenaline Signup and view all the answers

Study Notes

Endocrinology Overview

The endocrine system integrates various physiological processes across the body.
Functions include regulation of metabolism, energy balance, water and electrolyte levels, stress response, growth, reproduction, circulation, and digestion.

Hormonal Regulation

Two pathways control hormone secretion:
- Central Regulation: Managed by the brain, involves negative feedback loops, neuroendocrine reflexes, and rhythms (e.g., diurnal); responses can be fast, slow, or long-term.
- Direct Regulation: Endocrine cells react to changes in extracellular fluid levels, allowing very rapid responses to immediate needs.

Hormone Classes

Peptides: Chains of amino acids (e.g., ADH, insulin); hydrophilic, stored before release.
Amines: Derived from tyrosine; includes catecholamines (hydrophilic) and thyroid hormones (lipophilic).
Steroids: Derived from cholesterol; lipophilic, not stored but released via diffusion.
Hydrophilic hormones cannot cross the plasma membrane and act quickly, while lipophilic hormones diffuse across membranes and have slower onset effects.

Metabolism

Metabolism encompasses all chemical reactions in the body, including energy use for external (skeletal muscle movements) and internal (life-sustaining processes) activities.
The rate of energy expenditure is termed metabolic rate, typically measured in Calories/hr or kJ/hr, with components including basal metabolic rate (BMR) and additional energy for activities.
BMR is predominantly influenced by thyroid hormones.

Thyroid Gland Structure and Function

The thyroid gland, located over the trachea, consists of lobes containing follicles with follicular cells and colloid.
Produces thyroid hormones (T3 and T4) from tyrosine and iodine; T4 is converted to T3 in tissues, with T3 being four times more potent.
Thyroid hormones (TH) are lipophilic, transported in plasma bound to carrier proteins, maintaining a balance of free and bound hormone.

Effects of Thyroid Hormones

TH enhances basal metabolic rate and heat production.
Influences fuel metabolism, affecting the synthesis and breakdown of proteins, fats, and carbohydrates.
Exhibits sympathemimetic effects, increasing heart responsiveness to adrenaline and noradrenaline, thus enhancing heart rate and contractility.
Permissive effects on growth and development, particularly in the central nervous system (CNS), amplifying the effects of growth hormone.

Control of Thyroid Function

TH synthesis and release are regulated by the hypothalamus, which secretes thyrotropin-releasing hormone (TRH).
TRH stimulates the anterior pituitary to release thyroid-stimulating hormone (TSH), which in turn prompts the thyroid gland to release T3 and T4.

Summary Points

The endocrine system coordinates physiological functions through hormonal signaling, which can be centrally or directly regulated.
Hormone classification impacts functionality; peptides, amines, and steroids exhibit distinct storage and release characteristics.
Thyroid hormones play a crucial role in metabolic regulation, BMR enhancement, heat production, and supporting overall growth and development processes.

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Description

This quiz covers key concepts of endocrinology, focusing on the hormonal control of metabolism. You will refresh your knowledge about the functions of the endocrine system, classes of hormones, and the specific roles of the thyroid gland and its hormones.