Endocrine System Lecture Review

Flashcards covering the functional anatomy, hormones, and regulation of the endocrine system, including the hypothalamus, pituitary, thyroid, parathyroid, adrenal glands, pancreas, and other glands.

What is the primary function of the endocrine system?

The endocrine system controls body activities, influencing cell metabolism, growth, development, and maintaining homeostasis by releasing hormones into the bloodstream.

What is the primary difference between endocrine glands and exocrine glands?

Endocrine glands release hormones directly into the bloodstream, while exocrine glands release substances through ducts to specific locations.

What are hormones?

Hormones are chemical messengers produced by glands that are transported through the bloodstream to target cells or organs to trigger a specific response.

What major processes do hormones control?

Hormones control major processes such as reproduction, regulation of metastasis, growth and development, and mobilization of body defenses.

Name the two main classifications of hormones based on their solubility and mechanism of action.

Hormones are classified as peptide hormones (hydrophilic) and steroid hormones (hydrophobic).

Describe how peptide hormones function.

Peptide hormones are derived from amino acids, stored in vesicles, are water-soluble, bind to receptors on the cell surface, and transduce signals rapidly via second messenger systems.

Describe how steroid hormones function.

Steroid hormones are derived from cholesterol, synthesized when needed, are hydrophobic (bound to protein carriers), bind to intracellular receptors, and alter gene expression, leading to slower but longer-duration effects.

What are the three main control mechanisms of hormone secretion?

The three main control mechanisms are humoral control, hormonal control, and neural control.

Provide an example of humoral control of hormone secretion.

Low levels of Ca2+ ions stimulate the parathyroid gland to secrete parathyroid hormone (PTH), or rising blood glucose levels stimulate the pancreas to secrete insulin.

Provide an example of hormonal control of hormone secretion.

Thyroid-stimulating hormone (TSH) from the pituitary gland stimulates the thyroid gland to produce thyroid hormone, or glucagon inhibits insulin release from the pancreas.

Provide an example of neural control of hormone secretion.

During exercise, the sympathetic nervous system stimulates the adrenal gland to secrete epinephrine and norepinephrine.

Explain the concept of negative feedback in hormone regulation.

Negative feedback is a homeostatic mechanism where the body's response reverses or causes the opposite effect of the original stimulus, such as insulin release stopping when blood glucose levels return to normal.

Explain the concept of positive feedback in hormone regulation.

Positive feedback is a rare mechanism that amplifies changes rather than reversing them, such as the release of oxytocin during labor, which stimulates more uterine contractions, leading to more oxytocin release.

Why is the hypothalamus-pituitary complex considered the 'command center' of the endocrine system?

It coordinates messages between the endocrine and nervous systems, secreting hormones that directly produce responses or regulate the synthesis and secretion of hormones from other glands.

What is the functional difference between the posterior pituitary and the anterior pituitary?

The posterior pituitary stores and secretes hormones (ADH and oxytocin) produced by the hypothalamus, while the anterior pituitary produces and secretes its own hormones (TSH, ACTH, FSH, LH, GH, Prolactin) under the regulation of hypothalamic hormones.

What hormones are produced by the hypothalamus and released by the posterior pituitary?

The hypothalamus produces Antidiuretic Hormone (ADH) and Oxytocin, which are stored and released by the posterior pituitary.

What are the functions of Antidiuretic Hormone (ADH)?

ADH (vasopressin) functions to reduce urine production by increasing water reabsorption by the kidneys and increases blood pressure.

What are the functions of Oxytocin?

Oxytocin stimulates uterine contractions during childbirth and triggers milk letdown during breastfeeding.

Name the four main hormones secreted by the anterior pituitary that control other endocrine glands.

Thyroid-stimulating hormone (TSH), Adrenocorticotropic hormone (ACTH), Follicle-stimulating hormone (FSH), and Luteinizing hormone (LH).

What are the two hormones produced by the anterior pituitary that do not affect other endocrine glands?

Growth hormone (GH) and Prolactin.

What are some conditions associated with abnormal growth hormone (GH) levels?

Too little GH can cause pituitary dwarfism, while too much GH can cause gigantism (in children) or acromegaly (in adults).

What two hormones does the thyroid gland produce?

The thyroid gland produces thyroid hormone (Thyroxine/T4 and Triiodothyronine/T3) and Calcitonin.

What is the primary role of thyroid hormone?

Thyroid hormone (T3 and T4) is crucial for regulating the metabolism of every cell in the body and affects growth and development.

What is the function of Calcitonin?

Calcitonin lowers blood calcium levels by promoting the deposition of calcium in bones and reducing calcium reabsorption in the kidneys, especially when hypercalcemia occurs.

What hormone does the parathyroid gland produce, and what is its main function?

The parathyroid gland produces Parathyroid Hormone (PTH), which increases blood calcium levels by releasing calcium from bones, reabsorbing it by the kidneys, and activating vitamin D to absorb calcium from the intestines.

Contrast the effects of calcitonin and parathyroid hormone (PTH) on blood calcium levels.

Calcitonin lowers blood calcium levels, while parathyroid hormone (PTH) raises blood calcium levels.

What is Myxedema?

Myxedema is adult hypothyroidism characterized by weight gain, lethargy, and cold intolerance due to high levels of TSH.

What is Graves' disease?

Graves' disease is hyperthyroidism, involving excessive thyroid hormone secretion, leading to weight loss, heat intolerance, and low levels of TSH.

Where are the adrenal glands located, and what are their two main parts?

The adrenal glands are located on top of each kidney, consisting of an outer adrenal cortex and an inner adrenal medulla.

What hormones are secreted by the adrenal medulla, and what is their function?

The adrenal medulla secretes epinephrine (adrenaline) and norepinephrine (noradrenaline), which are involved in the short-term 'fight or flight' stress response, increasing heart rate, breathing, and dilating pupils.

What types of hormones are produced by the adrenal cortex?

The adrenal cortex produces glucocorticoids (e.g., cortisol), mineralocorticoids (e.g., aldosterone), and a small amount of sex hormones.

What are the primary functions of glucocorticoids like Cortisol?

Glucocorticoids primarily raise blood glucose levels by promoting the breakdown of muscle proteins and fatty acid metabolism; they also have anti-inflammatory effects.

What is the main function of mineralocorticoids like Aldosterone?

Mineralocorticoids regulate salt and water balance by promoting renal reabsorption of sodium ions (Na+) and water, and renal excretion of potassium (K+).

What is Addison's disease?

Addison's disease is caused by hyposecretion of adrenal cortex hormones, leading to symptoms like skin bronzing, low blood glucose, low blood pressure, and severe dehydration.

What is Cushing's syndrome?

Cushing's syndrome is caused by hypersecretion of adrenal cortex hormones, resulting in symptoms such as a tendency to develop diabetes mellitus, hypertension, and fat deposition in the trunk and face.

What are the two primary endocrine hormones produced by the pancreas, and what are their main functions?

The pancreas produces insulin, which lowers blood glucose by stimulating cellular uptake, and glucagon, which increases blood glucose by stimulating the liver to break down glycogen.

What is the role of somatostatin in the pancreas?

Somatostatin, produced by delta cells, prevents the release of both insulin and glucagon, helping to prevent wide swings in blood glucose levels between meals.

What are the key differences between Type I and Type II Diabetes Mellitus?

Type I Diabetes Mellitus is an autoimmune disorder where the body does not produce insulin, while Type II Diabetes Mellitus occurs when the body's cells fail to respond to insulin production (insulin resistance).

What female sex hormones are produced by the ovaries?

The ovaries produce Estrogens and Progesterone.

What male sex hormone is produced by the testes?

The testes produce Androgens, primarily testosterone.

What is the function of the thymus gland, and what hormone does it secrete?

The thymus gland secretes thymosin, which stimulates the maturation of T-lymphocytes, playing an important role in immune function until puberty.

What hormone does the pineal gland secrete, and what is its primary function?

The pineal gland secretes melatonin, which regulates the body's circadian rhythm (biological clock), synchronizing the sleep-wake cycle with light and darkness.

What are Leptin and Ghrelin, and where are they produced?

Leptin is produced by adipose tissue and signals satiety, while Ghrelin is produced by the stomach and signals hunger.

How do the endocrine and nervous systems work together to maintain homeostasis?

The hypothalamus-pituitary complex serves as the main neural control center for all endocrine glands, with hormones driving homeostatic feedback loops to regulate body health and equilibrium.