Anatomy & Physiology PHAS5001: Endocrine System

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Questions and Answers

Which hormone is primarily responsible for regulating blood volume?

Thyroxine

Aldosterone (correct)

Cortisol

Adrenaline

What effect do thyroid hormones have on the body's use of nutrients?

Only stimulate lipogenesis

Do not affect metabolic rates

Increase the use of glucose and fatty acids (correct)

Decrease the use of glucose

What is the structural shape difference between the right and left adrenal glands?

Left is pyramidal, right is semi-lunar

Both are pyramidal in shape

Right is pyramidal, left is semi-lunar (correct)

Both are semi-lunar in shape

Which of the following regulates calcium homeostasis?

Parathyroid hormone Signup and view all the answers

What type of cells are primarily found in the parathyroid gland?

Chief cells and oxyphil cells Signup and view all the answers

What is the primary function of the endocrine system?

To maintain homeostasis Signup and view all the answers

Which type of hormones have receptors located on the cell surface?

Polypeptides Signup and view all the answers

Which method of hormone communication acts on the same cell that produces the hormone?

Autocrine Signup and view all the answers

What class of hormones can cross the cell membrane due to being lipid soluble?

Steroids Signup and view all the answers

What role do feedback mechanisms play in hormone activity?

They regulate hormone release and function Signup and view all the answers

Which of the following hormones are not lipid soluble?

Insulin Signup and view all the answers

Which type of hormones circulate throughout the body via the bloodstream?

Circulating hormones Signup and view all the answers

What is the main difference between endocrine and paracrine signaling?

Paracrine signaling acts locally while endocrine acts at a distance Signup and view all the answers

Which type of hormone acts on the same cell that secreted it?

Autocrine hormone Signup and view all the answers

Where is the hypothalamus located in the brain?

In the diencephalon region Signup and view all the answers

Which hormone is primarily released by the posterior pituitary?

Antidiuretic hormone Signup and view all the answers

What type of mechanism do water-soluble hormones utilize to exert their effects?

Activation of second messenger systems Signup and view all the answers

What is a primary function of the anterior pituitary gland?

Release hormones in response to hypothalamic signals Signup and view all the answers

Which blood vessels supply the anterior pituitary gland with hormones from the hypothalamus?

Hypophyseal portal vessels Signup and view all the answers

What type of hormones bind to intracellular receptors and include examples like steroid hormones?

Lipid-soluble hormones Signup and view all the answers

What is the primary anatomical connection between the hypothalamus and the posterior pituitary?

The pituitary stalk Signup and view all the answers

What hormone is primarily responsible for stimulating the release of thyrotrophin (TSH) from the anterior pituitary?

Thyroid Releasing Hormone (TRH) Signup and view all the answers

Which hormone is NOT secreted by the anterior pituitary gland?

Oxytocin Signup and view all the answers

Which of the following statements about the thyroid gland is inaccurate?

It is located posterior to the trachea. Signup and view all the answers

Which of the following hormones regulates the metabolism of most cells by acting on the thyroid gland?

Thyroxine (T4) Signup and view all the answers

The thyroid gland receives its blood supply primarily from which arteries?

Superior and inferior thyroid arteries Signup and view all the answers

Which statement accurately describes the drainage of the adrenal veins?

The right adrenal vein drains into the inferior vena cava while the left adrenal vein drains into the left renal vein. Signup and view all the answers

What are the primary mineral ions regulated by aldosterone?

Na+ and K+ Signup and view all the answers

Which of the following sequences correctly describes the renin-angiotensin-aldosterone pathway?

Decrease blood pressure → kidney secretes renin → angiotensin I converted into angiotensin II → stimulates aldosterone secretion. Signup and view all the answers

Which effect is primarily caused by glucocorticoids like cortisol?

Breakdown of triglycerides for energy. Signup and view all the answers

What is the predominant catecholamine released during the fight or flight response?

Epinephrine Signup and view all the answers

What is the primary function of the pancreas in relation to hormone secretion?

Dual function: endocrine into bloodstream and exocrine via ducts. Signup and view all the answers

Which structure in the pancreas contains the cells responsible for hormone production?

Islets of Langerhans Signup and view all the answers

How does aldosterone primarily affect the kidneys?

Increases the reabsorption of Na+ leading to water reabsorption. Signup and view all the answers

Study Notes

Endocrine System Overview

Maintains homeostasis by using hormones as chemical messengers.
Homeostasis refers to keeping a stable internal environment for optimal functioning.

Function of Hormones

Hormones act in response to stimuli to restore equilibrium.
Affect specific target tissues that possess corresponding receptors.
Water-soluble hormones target cell surface receptors; lipid-soluble hormones bind to intracellular receptors.

Communication Mechanisms

Endocrine: Hormones transmitted via the circulatory system over long distances.
Paracrine: Hormones act on neighboring cells in extracellular fluid.
Autocrine: Hormones act on the same cell that secreted them.
Neuroendocrine: Hormones secreted from nerve cells.

Types of Hormones

Polypeptides: Water-soluble, cannot pass through cell membranes.
Steroids: Lipid-soluble, can cross cell membranes.
Modified Amino Acids: Small and water-soluble, can pass through cell membranes.
Eicosanoids: Local hormones like prostaglandins.

Hormone Types

Circulating Hormones: Travel in the bloodstream (e.g., insulin).
Local Hormones: Act in proximity to secretion site:
- Paracrine: Affect neighboring cells.
- Autocrine: Affect the secreting cell itself (e.g., interleukin-1).

Mechanisms of Hormone Action

Lipid-soluble hormones trigger responses within target cells.
Water-soluble hormones utilize second messenger systems for signal amplification.

Hypothalamic-Pituitary Axis

Central regulatory component of the endocrine system.
Hypothalamus integrates neural and hormonal signals and communicates with the pituitary gland.

Hypothalamus Details

Located at the base of the forebrain.
Connects to the pituitary gland via the pituitary stalk.
Receives signals from blood circulation and neuronal inputs, leading to hormone secretion.

Pituitary Gland

Anterior Pituitary: Releases hormones in response to hypothalamic stimuli, acting on other endocrine organs.
Posterior Pituitary: Connected to hypothalamus, releases ADH and oxytocin.

Thyroid Gland

Located anterior to the trachea, butterfly-shaped.
Functions include releasing calcitonin, T3, and T4 for metabolism regulation.
Regulated by anterior pituitary gland via TSH.

Actions of Thyroid Hormones

Increase basal metabolic rate and body temperature.
Stimulate glucose and fatty acid usage.
Promote lipolysis and support nervous tissue and bone development.

Parathyroid Glands

Located behind the thyroid gland, regulating calcium and phosphate homeostasis.
Contains chief cells and is regulated by calcium levels.

Adrenal Glands

Paired glands above each kidney, comprised of medulla and cortex.
Medulla secretes catecholamines (epinephrine and norepinephrine).
Cortex produces glucocorticoids (cortisol), mineralocorticoids (aldosterone), and androgens.

Aldosterone Function

Regulates sodium and potassium homeostasis, affecting blood pressure.
Part of the renin-angiotensin-aldosterone system, responding to low blood volume and pressure.

Glucocorticoids

Cortisol is the main glucocorticoid, released during stress.
Effects include protein breakdown, gluconeogenesis, lipolysis, and anti-inflammatory responses.

Catecholamines

Adrenaline (80%) and norepinephrine (20%) are involved in the fight or flight response.
Results in increased heart rate, blood flow to muscles, airway dilation, and energy production.

Pancreas Overview

Retroperitoneal gland with both endocrine (Islets of Langerhans) and exocrine (acini) functions.
Blood supply varies throughout its structure, with significant branches from the splenic artery and the pancreaticoduodenal artery.

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Description

Explore the intricacies of the endocrine system in this quiz based on PHAS5001. Learn about hormones, the main organs involved, their functions, and how these relate to various disease processes. Test your knowledge and deepen your understanding of this vital body system.