Endocrine System Overview

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Questions and Answers

Which cells in the thyroid produce calcitonin?

  • Oxyphil cells
  • Chief cells
  • Follicle cells
  • Parafollicular (correct)

Which layer of the adrenal cortex is responsible for producing glucocorticoids?

  • Zona fasciculata (correct)
  • Zona reticularis
  • Zona glomerulosa
  • Adrenal medulla

What is the function of the alpha cells in the islets of Langerhans?

  • Produce insulin
  • Produce thyroglobulin
  • Produce glucagon (correct)
  • Produce somatostatin

Which hormone is primarily produced by the chief cells of the parathyroid glands?

<p>Parathyroid hormone (A)</p> Signup and view all the answers

The adrenal medulla produces catecholamines in response to what type of stimulation?

<p>Sympathetic nervous system (B)</p> Signup and view all the answers

Which hormone is associated with the anterior pituitary and regulates the function of other endocrine glands?

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

What condition is characterized by excessive growth hormone in childhood?

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

What is the primary function of the pineal gland?

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

Which condition is caused by a deficiency of antidiuretic hormone (ADH)?

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

The thyroid gland's shape can be described as?

<p>Butterfly-shaped (A)</p> Signup and view all the answers

What hormone is produced by the pinealocytes in the pineal gland?

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

Which hormone is primarily responsible for stimulating ovulation?

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

What is the consequence of a pineal gland tumor in children?

<p>Accelerated onset of puberty (B)</p> Signup and view all the answers

Which glands are considered purely endocrine organs?

<p>Pituitary, Pineal, Thyroid, Adrenal (A)</p> Signup and view all the answers

Which statement accurately describes the two lobes of the pituitary gland?

<p>The posterior lobe has no endocrine cells but contains axon terminals. (A)</p> Signup and view all the answers

What is the primary role of the hormones released by the hypothalamus?

<p>Control the hormonal release from the anterior pituitary (B)</p> Signup and view all the answers

Which two hormones are secreted by the posterior lobe of the pituitary gland?

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

What type of hormones do the adrenal glands produce?

<p>Both fat-soluble and water-soluble hormones (B)</p> Signup and view all the answers

What anatomical feature allows the anterior lobe of the pituitary gland to communicate with the hypothalamus?

<p>The hypothalamo-hypophyseal portal veins (D)</p> Signup and view all the answers

In terms of endocrine function, which of the following organs is a mixed gland?

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

Which of these is NOT a major function of the endocrine system?

<p>Short-term regulation of blood pressure (C)</p> Signup and view all the answers

Flashcards

Endocrine system's role

The endocrine system is a major control system of the body that regulates long-term processes like growth, metabolism, reproduction, and defense.

Endocrine organs and hormones

Endocrine organs produce hormones, which are chemical messengers that regulate various bodily functions.

Types of hormones

Hormones can be either fat-soluble (steroid hormones) or water-soluble (amino acid-based hormones).

Location of the pituitary gland

The pituitary gland is a small, pea-sized gland located in the cranial cavity and hangs from the hypothalamus.

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Lobes of the pituitary gland

The pituitary gland consists of two lobes: the anterior lobe (adenohypophysis) and the posterior lobe (neurohypophysis).

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Anterior pituitary function

The anterior lobe of the pituitary gland contains endocrine cells that produce hormones. The hypothalamic stimulating and inhibiting hormones reach these cells through the hypothalamo-hypophyseal portal veins.

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Posterior pituitary function

The posterior lobe of the pituitary gland contains axons from hypothalamic neurons that secrete oxytocin and vasopressin. These hormones are released into the bloodstream.

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Hormones secreted by the pituitary gland

The pituitary gland secretes a total of 9 hormones, which are responsible for regulating various functions within the body.

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What are tropic hormones?

Hormones secreted by the anterior pituitary that regulate the function of other endocrine glands.

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What is TSH?

A hormone that stimulates the thyroid gland to produce thyroid hormones.

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What is ACTH?

A hormone that stimulates the adrenal cortex to produce cortisol.

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What is FSH?

A hormone that stimulates the ovaries to produce eggs and the testes to produce sperm.

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What is LH?

A hormone that triggers ovulation in females and testosterone production in males.

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What is GH?

A hormone secreted by the anterior pituitary that promotes growth.

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What is PRL?

A hormone that stimulates milk production in females.

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Where is the pineal gland located and what does it produce?

The pineal gland is located in the brain and produces melatonin.

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What is the thyroid gland?

The thyroid gland is a butterfly-shaped gland located in the neck, responsible for producing hormones that regulate metabolism.

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What are thyroid follicles?

Thyroid follicles are spherical structures within the thyroid gland that produce and store thyroid hormone.

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Where are the parathyroid glands located?

Parathyroid glands are small, pea-sized glands located on the posterior surface of the thyroid gland. They produce parathyroid hormone, which regulates calcium levels in the blood.

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What are the adrenal glands?

The adrenal glands are located on top of the kidneys and are composed of two parts: the adrenal cortex and the adrenal medulla. The adrenal cortex produces steroid hormones like cortisol, while the adrenal medulla produces catecholamines like adrenaline.

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What is the pancreas?

The pancreas is a gland that produces both digestive enzymes and hormones. The endocrine part of the pancreas, called the islets of Langerhans, produces hormones like insulin and glucagon, which regulate blood sugar levels.

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Study Notes

Endocrine System Overview

  • The endocrine system is a major control system for the body, regulating long-term processes like growth, development, metabolism, reproduction, and defense.
  • It achieves this through hormones.
  • Endocrine organs are either mixed glands (endocrine and exocrine functions) or purely hormone-producing.
  • Hormones are categorized by solubility—fat-soluble (steroid) or water-soluble (amino acid-based).

Learning Objectives

  • Students should be able to identify the glands of the endocrine system.
  • Describe locations, parts, hormones, and relationships of glands.
  • Correlate anatomical data with clinical applications.

Organs of the Endocrine System

  • Purely Endocrine Organs:
    • Pituitary gland
    • Pineal gland
    • Thyroid gland
    • Parathyroid glands
    • Adrenal glands (cortex and medulla)
  • Endocrine Cells in Other Organs:
    • Pancreas
    • Thymus
    • Gonads (testes and ovaries)
    • Hypothalamus

Pituitary Gland (Hypophysis Cerebri)

  • The master gland of the endocrine system.
  • Pea-sized (approximately 0.5 grams).
  • Located in the cranial cavity, connected to the hypothalamus via a stalk.
  • Houses two main lobes:
    • Adenohypophysis (anterior lobe): glandular; contains endocrine cells.
    • Neurohypophysis (posterior lobe): neural; contains axon terminals from hypothalamic neurons.
  • The anterior pituitary is controlled by the hypothalamus via hypothalamo-hypophyseal portal veins.
  • The posterior pituitary is connected to the hypothalamus by the hypothalamo-hypophyseal tract and releases hormones like oxytocin and vasopressin (ADH). The hormones are released into the blood and carried to target organs.

Pituitary Gland Hormones

  • Anterior Pituitary:
    • Thyroid-stimulating hormone (TSH)
    • Adrenocorticotropic hormone (ACTH)
    • Follicle-stimulating hormone (FSH)
    • Luteinizing hormone (LH)
    • Growth hormone (GH)
    • Prolactin (PRL)
    • Melanocyte-stimulating hormone (MSH)
  • Posterior Pituitary:
    • Antidiuretic hormone (ADH)
    • Oxytocin

Pituitary Gland Clinical Applications

  • Gigantism (too much GH in childhood)
  • Acromegaly (too much GH in adulthood)
  • Pituitary dwarfism (too little GH in childhood)
  • Diabetes insipidus (less ADH)

Pineal Gland

  • Part of the epithalamus, located in the posterior wall of the third ventricle.
  • Pine-cone shaped (approximately 6mm).
  • Consists of:
    • Pinealocytes (hormone-secreting cells)
    • Glial cells (supporting cells)
  • Produces melatonin, a hormone that regulates sex-gland function and helps protect from free radicals.
  • In some cases, produces accelerated puberty in children, due to tumors.

Thyroid Gland

  • Located in the lower anterior part of the neck.
  • Butterfly-shaped, with two lobes connected by an isthmus.
  • Lies lateral to the larynx, trachea, pharynx, and esophagus.
  • Isthmus sits in front of the upper trachea.
  • Plays a vital role in body metabolism and regulates metabolic processes.
  • Contains:
    • Follicle cells: produce thyroglobulin (precursor to thyroxin).
    • Colloid lumen: contains thyroglobulin.
    • Parafollicular (C) cells: produce calcitonin.
  • Clinical conditions related to the thyroid include goiter, hyperthyroidism, and hypothyroidism.

Parathyroid Glands

  • Four glands embedded on the posterior surface of the thyroid lobes.
  • Composed of:
    • Chief cells: produce parathyroid hormone.
    • Oxyphil cells: unknown function.

Adrenal (Suprarenal) Glands

  • Located on the upper pole of each kidney.
  • Composed of two glands:
    • Adrenal cortex: produces steroid hormones. The cortex has 3 layers:
      • Zona glomerulosa: produces mineralocorticoids.
      • Zona fasciculata: produces glucocorticoids.
      • Zona reticularis: produces sex steroids (androgens).
    • Adrenal medulla: produces catecholamines (epinephrine and norepinephrine) in response to sympathetic nervous system stimulation.
  • A clinical condition related to adrenal glands is Cushing's syndrome.

Pancreas

  • The endocrine portion of the pancreas are islets of Langerhans, scattered between exocrine acini.
  • Islets contain:
    • Alpha cells: produce glucagon.
    • Beta cells: produce insulin.
    • Dita cells: produce somatostatin
  • Diabetes mellitus is a clinical concern.

Gonads

  • (Testicles and ovaries) are discussed in the reproductive systems.

Thymus

  • Discussed with the lymphatic system.

Hypothalamus

  • Part of the diencephalon.
  • A higher control center for the endocrine system, which influences the pituitary gland and other endocrine tissues.

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