Endocrine System Overview

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Questions and Answers

What is the primary function of hormones in the endocrine system?

  • To facilitate nerve communication
  • To transport nutrients
  • To digest food
  • To regulate internal body processes (correct)

Which type of signaling do hormones utilize to affect distant target cells?

  • Endocrine signaling (correct)
  • Paracrine signaling
  • Electrical signaling
  • Autocrine signaling

What distinguishes endocrine glands from exocrine glands?

  • Endocrine glands use electrical signals for communication.
  • Endocrine glands have ducts for secretion.
  • Endocrine glands secrete products into ducts.
  • Endocrine hormones enter the bloodstream. (correct)

What is a characteristic of steroid hormones?

<p>They require transport proteins in the blood. (D)</p> Signup and view all the answers

Which hormone is primarily involved in the regulation of water balance in the body?

<p>Antidiuretic hormone (ADH) (D)</p> Signup and view all the answers

What role does the hypothalamus play in the endocrine system?

<p>It produces and regulates hormones released by the pituitary gland. (C)</p> Signup and view all the answers

Which of the following hormones is regulated by a positive feedback loop?

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

Which statement is true about peptide hormones?

<p>They are stored in vesicles until needed. (B)</p> Signup and view all the answers

What effect does downregulation have on target cell receptors?

<p>Decreased sensitivity to hormone (A)</p> Signup and view all the answers

Which hormones are produced by the posterior pituitary gland?

<p>Oxytocin and antidiuretic hormone (ADH) (D)</p> Signup and view all the answers

What is the role of antidiuretic hormone (ADH) in kidney function?

<p>It helps the kidneys reabsorb water. (C)</p> Signup and view all the answers

What is the primary mechanism that regulates most hormones in the body?

<p>Negative feedback loops (B)</p> Signup and view all the answers

Which factor can directly influence hormone secretion?

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

What condition results from the underproduction of antidiuretic hormone?

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

Where are lipid-soluble hormone receptors typically located?

<p>Inside the cytosol or nucleus (C)</p> Signup and view all the answers

Which statement about the anterior pituitary gland is correct?

<p>It produces hormones regulated by tropic hormones from the hypothalamus. (D)</p> Signup and view all the answers

Which hormone is primarily responsible for stimulating growth during childhood?

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

How does excessive secretion of growth hormone during childhood affect height?

<p>It leads to substantially increased height. (D)</p> Signup and view all the answers

What potential complication can arise from acromegaly?

<p>Increased risk of cardiovascular issues (A)</p> Signup and view all the answers

What distinguishes the posterior pituitary gland from the anterior pituitary gland?

<p>It directly secretes hormones from the hypothalamus. (A)</p> Signup and view all the answers

What does the term 'hypothalamic-hypophyseal portal system' refer to?

<p>The connection between the hypothalamus and the anterior pituitary. (A)</p> Signup and view all the answers

What is a characteristic effect of lipolysis stimulated by growth hormone?

<p>Increased muscle mass (D)</p> Signup and view all the answers

What condition may occur due to severe ion imbalances as a result of Diabetes Insipidus?

<p>Lonic imbalances (A)</p> Signup and view all the answers

What is the relationship between acromegaly and the cartilage in adults?

<p>It causes increased cartilage growth. (B)</p> Signup and view all the answers

What is the function of desmopressin in relation to antidiuretic hormone?

<p>It acts as an artificial form of ADH. (D)</p> Signup and view all the answers

What is the consequence of lack of adequate water reabsorption in the kidneys?

<p>Increased urine output (B)</p> Signup and view all the answers

What is the role of calcitonin in calcium regulation?

<p>Decreases blood calcium levels (D)</p> Signup and view all the answers

What distinguishes the effects of follicle-stimulating hormone (FSH) from luteinizing hormone (LH)?

<p>FSH promotes gamete production, while LH stimulates release of sex hormones (A)</p> Signup and view all the answers

Which condition is characterized by the excessive production of thyroid hormones?

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

How does growth hormone primarily exert its effects?

<p>By stimulating the production of insulin-like growth factors (C)</p> Signup and view all the answers

What is the physiological effect of parathyroid hormone (PTH)?

<p>Stimulates osteoclasts to resorb bone (A)</p> Signup and view all the answers

What is the primary function of thyroid hormones in metabolism?

<p>Increase basal metabolic rate (A)</p> Signup and view all the answers

Which hormone primarily regulates the stress response in the body?

<p>Adrenocorticotropic hormone (ACTH) (D)</p> Signup and view all the answers

In which part of the body is the thyroid gland located?

<p>Anterior to the trachea and inferior to the larynx (C)</p> Signup and view all the answers

What condition might result from insufficient production of thyroid hormones?

<p>Weight gain and cold intolerance (D)</p> Signup and view all the answers

What stimulates the release of thyroid hormones from the thyroid gland?

<p>TRH from the hypothalamus (D)</p> Signup and view all the answers

Which hormone is secreted in response to elevated blood calcium levels?

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

What is a common result of hyperparathyroidism?

<p>Decreased responsiveness of the nervous system (C)</p> Signup and view all the answers

What is the primary mineralocorticoid secreted by the zona glomerulosa of the adrenal cortex?

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

Which hormone is essential for the fight-or-flight response?

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

Flashcards

Endocrine System

The endocrine system is a collection of glands that produce and secrete hormones, which are chemical messengers that travel through the bloodstream to regulate various bodily functions. It plays a crucial role in maintaining homeostasis by influencing metabolism, growth, development, reproduction, and many other processes.

Hormones

Hormones are chemical messengers produced by endocrine glands that travel through the bloodstream to target cells, triggering specific physiological responses.

Nervous vs Endocrine System

The endocrine system uses chemical messengers called hormones to communicate and regulate cellular processes, while the nervous system utilizes electrical signals transmitted via neurons.

Antidiuretic Hormone (ADH)

A hormone produced by the posterior pituitary gland that helps regulate water balance in the body by increasing water reabsorption in the kidneys.

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Diabetes Insipidus

A condition characterized by excessive thirst and urine production due to a deficiency in antidiuretic hormone (ADH).

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Infundibulum

The connection between the hypothalamus and the posterior pituitary gland, allowing for the transport of hormones like ADH.

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Hypothalamic-Hypophyseal Portal System

The connection between the hypothalamus and the anterior pituitary gland, transporting hormones through a network of blood vessels.

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Anterior Pituitary Gland

The anterior pituitary gland is composed of glandular tissue. It produces and secretes six major hormones.

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Growth Hormone (GH)

A hormone produced by the anterior pituitary gland that promotes growth and development.

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Pituitary Dwarfism

A condition characterized by abnormally short stature due to a deficiency in growth hormone (GH) production during childhood.

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Gigantism

A condition characterized by excessive growth and height due to overproduction of growth hormone (GH) during childhood.

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Acromegaly

A condition characterized by excessive growth of bones, cartilage, and soft tissues in adults due to the overproduction of growth hormone (GH). It often affects the hands, feet, and face.

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Thyroid Stimulating Hormone (TSH)

A hormone produced by the anterior pituitary gland that stimulates the production of thyroid hormones (T3 and T4).

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Thyroid Hormones (T3 and T4)

Hormones produced by the thyroid gland that regulate metabolism and energy production.

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Adrenocorticotropic Hormone (ACTH)

A hormone produced by the anterior pituitary gland that stimulates the production of cortisol by the adrenal glands.

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Follicle-Stimulating Hormone (FSH)

A hormone produced by the anterior pituitary gland that stimulates the production of sex hormones (estrogen in females and testosterone in males).

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Luteinizing Hormone (LH)

A hormone produced by the anterior pituitary gland that triggers ovulation in females and stimulates the production of testosterone in males.

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Prolactin

A hormone produced by the anterior pituitary gland that stimulates milk production in females.

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Where is the thyroid gland located?

The thyroid gland is located anterior to the trachea and inferior to the larynx, consisting of two lateral lobes connected by an isthmus.

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What are the structural units of the thyroid gland?

The spherical units of the thyroid gland are called thyroid follicles, each containing an internal cavity filled with colloid.

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What produces Thyroid hormone?

Thyroid hormone (TH) is produced by follicular cells, stimulated by TSH from the Anterior Pituitary gland.

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What hormone does the thyroid gland release in response to high calcium levels?

The thyroid gland produces and secretes calcitonin, which is secreted in response to elevated blood calcium levels.

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How does calcitonin decrease blood calcium levels?

Calcitonin decreases blood calcium levels by inhibiting osteoclast activity, stimulating osteoblast activity, decreasing calcium absorption by the intestines, and increasing calcium loss in the urine.

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Where are the parathyroid glands located?

Parathyroid glands are located on the posterior side of the thyroid gland, composed of two cell types: chief cells and oxyphil cells.

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What do the Chief cells in the parathyroid glands secrete?

Chief cells in the parathyroid glands secrete parathyroid hormone (PTH) in response to low calcium levels, which increases blood calcium levels.

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How does PTH increase blood calcium levels?

PTH increases blood calcium levels by stimulating osteoclasts to break down bone matrix, inhibiting osteoblasts, and stimulating calcitriol production to increase dietary calcium absorption.

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Where are the adrenal glands located?

The adrenal glands are located on top of each kidney, divided into the adrenal cortex and medulla.

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What are the zones of the adrenal cortex called?

The adrenal cortex is composed of three zones: Zona Glomerulosa, Zona Fasciculata, and Zona Reticularis.

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What is the most superficial region of the adrenal cortex, and what does it secrete?

The Zona Glomerulosa, the most superficial region of the adrenal cortex, secretes mineralocorticoids.

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What is the main mineralocorticoid, and what is its function?

Aldosterone, the main mineralocorticoid, increases sodium and water reabsorption by the kidneys, ultimately increasing blood pressure.

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What does the Zona Fasciculata secrete?

The Zona Fasciculata, the intermediate region of the adrenal cortex, secretes glucocorticoids, with cortisol being the main one.

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What is the main glucocorticoid, and what are its functions?

Cortisol, the main glucocorticoid, is released in response to stress, suppressing the immune system, stimulating the breakdown of stored nutrients for energy such as glycogenolysis, lipolysis, and gluconeogenesis.

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What does the Zona Reticularis secrete, and what is the main androgen?

The Zona Reticularis, the deepest region of the adrenal cortex, secretes androgens, with dehydroepiandrosterone (DHEA) being the main one.

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Study Notes

Endocrine System

  • Facilitates long-distance communication using electrical signals (nervous system) and hormones (endocrine system)
  • Nervous system uses neurotransmitters
  • Endocrine system uses hormones (chemical signaling molecules) that travel in blood, reaching most cells and affecting many functions
  • Functions: regulates calorie and nutrient use, waste secretion, blood pressure, blood osmolarity, growth, fertility, sex drive, lactation, sleep.
  • Chemical Signaling: uses hormones (released into blood, or affecting neighboring cells - paracrine, or affecting same cell - autocrine), hormones only affect target cells (with receptors for a specific hormone)
  • Nervous vs. Endocrine: neurotransmitters vs. hormones, nervous system is faster, endocrine effects are more widespread and longer lasting.

Endocrine Glands

  • Pituitary (anterior and posterior), thyroid, parathyroid, adrenal, and pineal glands: mainly secrete hormones.
  • Hormones affect target cells.
  • Other organs with endocrine function: hypothalamus, thymus, heart, kidneys, stomach, small intestine, liver, adipose tissue, ovaries, and testes. Target cells have receptors for specific hormones.

Hormone Types

  • Steroid hormones: lipid-based, easily cross cell membranes, require carrier proteins in blood, produced from cholesterol. Examples: testosterone, estrogens
  • Amine hormones: modified amino acids, water-soluble, cannot cross cell membranes, do not require transport proteins. Examples: melatonin, epinephrine, norepinephrine
  • Peptide and protein hormones: chains of amino acids, water-soluble, cannot cross cell membranes, do not require transport proteins. Examples: antidiuretic hormone, insulin.

Hormone Receptors

  • Intracellular (cytosol or nuclear) for lipid-soluble hormones (steroid hormones); on cell surface for water-soluble hormones. Hormone binding initiates intracellular signaling pathways/alterations within cells

Second Messenger System

  • Crucial for water-soluble hormone signaling, involving a series of steps after binding to cell surface receptors. A protein called a G-protein activates enzymes, initiating a cascade of reactions that ultimately change cell function.

Anatomy of Steroid Hormones

  • Made on demand.
  • Secreted into blood, transported by proteins.
  • Bind to intracellular receptors inside the target cell.

Anatomy of Protein Hormones

  • Made by rough ER or ribosomes.
  • Secreted into blood, often without transport proteins needed

Endocrine Control

  • Negative feedback loops often regulate hormone release (as hormone levels rise, secretion slows or stops).
  • Positive feedback loops exist for some, such as oxytocin (stimulates further release in childbirth).
  • Hypothalamus and pituitary gland: regulate many endocrine functions and release hormones

Pituitary Gland

  • Anterior pituitary: makes and secretes many tropic hormones, including growth hormone, thyroid-stimulating hormone, adrenocorticotropic hormone, follicle-stimulating hormone, luteinizing hormone, and prolactin.
  • Posterior pituitary: stores and secretes oxytocin and antidiuretic hormone (ADH)

Thyroid Gland

  • Thyroid hormones (T3 and T4): regulate metabolism, growth, and development, stimulated by TSH
  • Hyperthyroidism: excessive production; Hypothyroidism: insufficient production. Affects metabolism and nervous system

Parathyroid Glands

  • Parathyroid hormone (PTH): regulates blood calcium levels (antagonist hormone to calcitonin)

Adrenal Glands

  • Adrenal cortex: mineralocorticoids, glucocorticoids, and androgens influence electrolyte balance, stress response, and sexual development
  • Adrenal medulla: epinephrine and norepinephrine; fight or flight response.

Hormones in specific zones

  • Zona glomerulosa: mineralocorticoids
  • Zona Fasciculata: glucocorticoids
  • Zona Reticularis: androgens

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