Endocrine Control of Growth: Adrenal Glucocorticoids

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Questions and Answers

What is the primary effect of cortisol in response to long-term stress?

Promotes protein synthesis

Enhances lipolysis (correct)

Increases immune response

Reduces blood glucose levels

Which condition is characterized by excessive cortisol secretion?

Cushing's syndrome (correct)

Grave's disease

Addison's disease

Hypothyroidism

What are common symptoms of hypocortisolism?

Weight gain and high blood pressure

Exophthalmos and increased heart rate

Hyperglycemia and tissue wasting

Hypoglycemia and fatigue (correct)

What distinguishes T3 from T4 regarding their biological activity?

T3 is biologically active but has a short half-life Signup and view all the answers

Which of the following could cause hypothyroidism?

Autoimmune diseases Signup and view all the answers

What is a common characteristic of hyperthyroidism?

Increased heart rate and heat production Signup and view all the answers

Which hormone is primarily affected in Addison's disease?

Cortisol Signup and view all the answers

What symptom is commonly associated with hypercortisolism?

Tissue wasting Signup and view all the answers

Which of the following can lead to a goiter?

Both hypothyroidism and hyperthyroidism Signup and view all the answers

What is a key feature of Grave's disease?

Exophthalmos Signup and view all the answers

What is the result of hypersecretion of growth hormone in children?

Giantism Signup and view all the answers

Which factor does NOT influence normal growth?

Chronic stress Signup and view all the answers

What is the primary function of parathyroid hormone (PTH)?

Raise plasma Ca2+ concentration Signup and view all the answers

Which hormone aids in the absorption of calcium in the intestines?

Calcitriol Signup and view all the answers

What is the main outcome of hyposecretion of growth hormone in adults?

Short stature Signup and view all the answers

How does calcitonin affect calcium levels in the body?

Promotes renal excretion of calcium Signup and view all the answers

Which statement is true regarding the distribution of calcium in the body?

It is distributed among extracellular fluid, intracellular Ca2+, and extracellular matrix. Signup and view all the answers

What stimulates the release of PTH?

Low plasma calcium levels Signup and view all the answers

Which of the following describes a hallmark of acromegaly?

Soft tissue growth Signup and view all the answers

What is the primary way calcium balance is regulated in the body?

By parathyroid hormone and calcitonin Signup and view all the answers

Study Notes

Endocrine Control of Growth and Metabolism - Adrenal Glucocorticoids

Cortisol secretion is controlled by ACTH
Cortisol is a steroid hormone, synthesized from cholesterol on demand, not stored
Transported in circulation bound to corticosteroid-binding globulin (produced by the liver)
Half-life of 60-90 minutes
Factors affecting release include circadian rhythm and stress
ACTH, from the anterior pituitary gland, is released in response to CRH (corticotropin-releasing hormone) from the hypothalamus
Cortisol targets many body tissues and has various effects

Cortisol's Mechanism of Action

Cortisol acts at the cellular level by binding to intracellular receptors
This leads to altered gene expression, stimulating transcription, translation, and protein synthesis
This ultimately affects various physiological processes

Cortisol's Metabolic Effects

Cortisol's effects are primarily catabolic
Promotes gluconeogenesis (glucose formation from non-carbohydrate sources)
Breaks down proteins from skeletal muscle
Increases lipolysis (fat breakdown)
Suppresses the immune system
Causes negative calcium balance
Influences brain function

Cortisol and Stress

Cortisol is a key mediator of long-term stress response

Hypercortisolism and Hypocortisolism

Hypercortisolism (too much cortisol): caused by adrenal tumors, Cushing's disease/syndrome
- Symptoms include hyperglycemia (high blood sugar) and tissue wasting
Hypocortisolism (too little cortisol): caused by hyposecretion of adrenal steroid hormones, Addison's disease
- Symptoms include hypoglycemia (low blood sugar), fatigue, and lack of appetite

Thyroid Hormones

Thyroid hormone secretion is controlled by the hypothalamic-pituitary-thyroid axis (HPT axis)
TRH from the hypothalamus stimulates the release of TSH from the anterior pituitary
TSH stimulates the thyroid gland to produce T3 (triiodothyronine) and T4 (thyroxine)
Both T3 and T4 have negative feedback mechanisms that regulate their own production
T3 is the biologically active form (though T4 is initially produced)
T4 converts to T3 in tissues and has a longer half-life
Thyroid hormones affect various metabolic processes, including oxygen consumption

Hyperthyroidism and Hypothyroidism

Hyperthyroidism leads to an overproduction of thyroid hormones; causes may include Graves' disease, accompanied by exophthalmos (eye bulging) and thyroid gland tumors
Hypothyroidism occurs due to inadequate hormone production; causes might be iodine deficiency, autoimmune issues, or treatment of other disorders
Goiters (enlarged thyroid glands) can occur in both hyperthyroidism and hypothyroidism

Growth Hormone

Factors influencing normal growth include growth hormone, adequate diet, absence of chronic stress, and genetics
Hypersecretion in children results in gigantism, while in adults it leads to acromegaly (disproportionate growth).
Hyposecretion leads to dwarfism

Calcium Balance

Calcium (Ca2+) is vital, acting as a signal molecule, a component of cell junctions, a cofactor in coagulation, and affecting nervous system and muscle function
Calcium is distributed among extracellular fluid, intracellular compartments, and the extracellular matrix (bone).
Hormones like parathyroid hormone (PTH), calcitriol (vitamin D), and calcitonin regulate calcium levels in different body compartments through bone resorption, intestinal absorption, and renal excretion mechanisms.

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Description

This quiz covers the fundamental aspects of adrenal glucocorticoids, particularly cortisol. It explores the mechanisms of cortisol secretion, its action at the cellular level, and its various metabolic effects. Test your understanding of how cortisol functions within the endocrine system and its role in metabolism.