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Questions and Answers
What is the primary type of catecholamine produced by the adrenal medulla?
What is the primary type of catecholamine produced by the adrenal medulla?
Which of the following is NOT a function of cortisol?
Which of the following is NOT a function of cortisol?
What is the main effect of aldosterone?
What is the main effect of aldosterone?
Which of the following statements about pheochromocytoma is accurate?
Which of the following statements about pheochromocytoma is accurate?
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What is the consequence of mineralocorticoid deficiency?
What is the consequence of mineralocorticoid deficiency?
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Which type of cells in the pancreas are responsible for secreting glucagon?
Which type of cells in the pancreas are responsible for secreting glucagon?
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What is the primary effect of insulin on blood glucose levels?
What is the primary effect of insulin on blood glucose levels?
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Which hormone is considered the principal glucocorticoid?
Which hormone is considered the principal glucocorticoid?
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Which factor is NOT known to stimulate the secretion of growth hormone?
Which factor is NOT known to stimulate the secretion of growth hormone?
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What is the primary action of anti-diuretic hormone (ADH) on the kidneys?
What is the primary action of anti-diuretic hormone (ADH) on the kidneys?
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Which of the following is a symptom of diabetes insipidus due to decreased ADH levels?
Which of the following is a symptom of diabetes insipidus due to decreased ADH levels?
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Which hormone from the thyroid gland is also known as T4?
Which hormone from the thyroid gland is also known as T4?
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What effect do T3 and T4 hormones have on the cardiovascular system?
What effect do T3 and T4 hormones have on the cardiovascular system?
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Which of the following actions is NOT associated with parathormone?
Which of the following actions is NOT associated with parathormone?
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Where are the parathyroid glands located?
Where are the parathyroid glands located?
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What is the main effect of oxytocin during childbirth?
What is the main effect of oxytocin during childbirth?
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What is the main function of growth hormone (GH)?
What is the main function of growth hormone (GH)?
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Which gland is responsible for secreting growth hormone?
Which gland is responsible for secreting growth hormone?
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How does growth hormone (GH) enhance its effects on growth?
How does growth hormone (GH) enhance its effects on growth?
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What is the relationship between growth hormone and protein synthesis?
What is the relationship between growth hormone and protein synthesis?
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Which metabolic effect does growth hormone (GH) have?
Which metabolic effect does growth hormone (GH) have?
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What pattern does the secretion of growth hormone follow?
What pattern does the secretion of growth hormone follow?
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Which of the following is NOT a function of growth hormone?
Which of the following is NOT a function of growth hormone?
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Gonadotrophic hormones, such as FSH and LH, are secreted by which part of the pituitary gland?
Gonadotrophic hormones, such as FSH and LH, are secreted by which part of the pituitary gland?
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Study Notes
Endocrine Glands Physiology
- Endocrine hormones are released by specialized glands or cells into the bloodstream.
- These hormones affect target cells in other locations within the body.
- The circulatory system transports hormones to target cells.
- Hormones bind to receptors and trigger cellular reactions.
Human Endocrine System
- The human endocrine system includes numerous glands and organs.
- These organs and glands are located throughout the body in various parts.
- Major organs and glands include the hypothalamus, pituitary gland (divided into anterior and posterior lobes), pineal gland, thyroid gland, thymus gland, adrenal glands, pancreas, and reproductive system (male/female).
Pituitary Gland
- Located on the inferior surface of the brain.
- Structurally and functionally divided into two parts.
- Anterior lobe (adenohypophysis) and posterior lobe (neurohypophysis).
Hypothalamus
- Secretes releasing and inhibiting hormones.
- These hormones control the pituitary.
- The hypothalamus secretes hormones that are directed to the anterior pituitary.
- Anterior pituitary hormones are released into the blood stream.
Anterior Pituitary Hormones
- Six important peptide hormones are secreted by the anterior pituitary.
- These hormones control various functions in the body.
- Growth hormone (GH).
- Prolactin (PRL).
- Thyroid-stimulating hormone (TSH).
- Adrenocorticotropic hormone (ACTH).
- Gonadotropic hormones (FSH and LH).
Growth Hormone (GH)
- Also known as somatotropin.
- Promotes growth of tissues.
- Stimulates liver to produce somatomedins that enhance bone and cartilage growth.
- Has metabolic effects including increased protein synthesis, mobilization of fatty acids, and decreased glucose utilization.
- Secretion patterns include pulsatile pattern and increases during deep sleep.
Metabolic Functions (Growth Hormone)
- Increases protein synthesis in most cells.
- Mobilizes fatty acids from adipose tissue leading to increased free fatty acids in the blood.
- Enhances body protein use, uses fat stores and conserves carbohydrates.
Posterior Pituitary Hormones
- These hormones, ADH and Oxytocin, are formed in the hypothalamus and stored in the posterior pituitary.
- Antidiuretic hormone (ADH) regulates water balance by affecting the kidneys.
Actions of ADH
- Acts on the kidneys, causing water reabsorption in the collecting ducts.
- Acts on blood vessels, it is the most potent vasoconstrictor, raising blood pressure.
ADH Regulation
- Blood osmotic pressure increases stimulate the release of ADH.
- Drinking reduces blood osmotic pressure which inhibits the release of ADH.
Effects of ADH Deficiency
- Diabetes insipidus: manifests with polyuria (excessive urine volume) and polydipsia (excessive water intake).
Oxytocin
- Stimulates uterine contractions during childbirth.
- Stimulates milk ejection in lactating mothers.
Thyroid Gland
- Located in the neck, below the larynx.
- One of the largest endocrine glands.
- Secretes two major hormones: thyroxine (T4) and triiodothyronine (T3).
- Also secretes calcitonin.
Thyroid Hormones
- Triiodothyronine (T3) and tetraiodothyronine (T4).
- Calcitonin Hormone.
Functions of T3 and T4
- Calorigenic effect: increases oxygen consumption and metabolism in body tissues.
- Metabolic effects (Protein Metabolism, Fat Metabolism, Carbohydrate Metabolism, Cardiovascular system, Gastrointestinal tract, Central nervous system.
Parathyroid Gland
- Four small glands located on the posterior surface of the thyroid.
- Secretes parathyroid hormone (PTH).
Functions of Parathyroid Hormone (PTH)
- Increases blood calcium levels.
- Decreases excretion of calcium in kidneys.
- Increases calcium absorption from small intestine.
Adrenal Gland
- Located on top of each kidney.
- Composed of two parts: cortex and medulla.
- Cortex secretes corticosteroids (mineralocorticoids, glucocorticoids, androgens).
- Medulla secretes catecholamines (epinephrine and norepinephrine).
Adrenal Medulla
- Modified sympathetic ganglion.
- Postganglionic sympathetic neurons lose axons and become secretory cells releasing catecholamines.
- Primarily epinephrine.
- Small percentage of norepinephrine.
Pheochromocytoma
- Tumor of adrenal medulla resulting in increased catecholamines.
- Manifestations include sustained hypertension, tachycardia, palpitation, hyperglycemia, and increased basal metabolic rate.
Adrenal Cortex
- Aldosterone: Principal mineralocorticoid.
- Cortisol: Principal glucocorticoid.
- Androgens: Small amounts of sex hormones.
Aldosterone
- Exclusively synthesized in the Zona glomerulosa.
- Essential for life, it promotes sodium retention and potassium and hydrogen elimination by the kidney.
- Expands ECF volume.
Hyperaldosteronism
- Primary hyperaldosteronism includes idiopathic hyperaldosteronism, adenomas, and glucocorticoid-suppressible aldosterone excess.
- Results in increased aldosterone resulting in hypertension.
Effects of Mineralocorticoid Deficiency
- Reduced sodium reabsorption.
- Reduced extracellular fluid volume.
- Reduced plasma volume.
- Decreased cardiac output and circulatory shock.
- Increased potassium and hydrogen ions.
- Possible cardiac and other toxicity.
Cortisol (Glucocorticoids)
- Affects many tissues, including immune systems, bones, liver, skeletal muscle, and more.
- Provides catabolic, lipolytic, hyperglycemic, anti-allergic, anti-inflammatory, and anti-stress actions.
Pancreas
- Contains endocrine and exocrine tissues.
- Includes pancreatic islets (islets of Langerhans containing alpha, beta, and delta cells).
- Alpha cells produce glucagon.
- Beta cells produce insulin and amylin.
- Delta cells produce somatostatin.
Insulin
- Lowers blood glucose levels (hypoglycemic effect) by increasing glucose uptake by tissues and increasing glycogenesis in the liver.
- Decreasing glycogenolysis and gluconeogenesis.
- Increasing lipogenesis. (lipogenic).
- Increasing protein synthesis (anabolic).
Glucagon
- Elevates blood glucose levels by activating glycogenolysis enzymes, inhibiting glycogenesis enzymes, and activating enzyme gluconeogenesis enzymes:
- Increases lipolysis and releases fatty acids into the blood, contributing to ketone body formation.
Diabetes Mellitus
- Characterized by chronic hyperglycemia and disturbances in carbohydrate, fat, and protein metabolism.
- Resulting from defects in insulin secretion, insulin action, or both.
Type 1 Diabetes
- Insulin-dependent diabetes mellitus (IDDM) or juvenile-onset diabetes.
- Develops when the body's immune system destroys pancreatic beta cells.
- Usually occurs in children and young adults.
Type 2 Diabetes
- Non-insulin-dependent diabetes mellitus (NIDDM) or adult-onset diabetes.
- Characterized by insulin resistance; cells do not use insulin properly.
- Pancreas gradually loses its ability to produce insulin.
- Associated with older age, obesity, family history of diabetes, history of gestational diabetes, and impaired glucose metabolism.
Polyphagia, Polydipsia, Polyuria
- Polyphagia: excessive hunger.
- Polydipsia: excessive thirst.
- Polyuria: excessive urine production.
- Symptoms common to diabetes.
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Description
Test your knowledge on the human endocrine system and its glands. This quiz covers the functions of major endocrine organs like the hypothalamus and pituitary gland, as well as the hormones they release. Understand how these hormones interact with target cells in the body.
