Endocrine System and Hormone Mechanisms

Flashcards to help review key concepts from the endocrine system and hormone mechanisms.

What are the pure endocrine organs?

Pituitary, pineal, thyroid, parathyroid, and adrenal glands.

What type of hormones are amine hormones?

Hormones modified from single amino acids, e.g., norepinephrine, epinephrine, melatonin.

What are polypeptide hormones?

Chains of amino acids typically ranging from 10 to 100 amino acids, e.g., ADH, GH.

Define glycoprotein hormones.

Hormones that consist of a protein bound to one or more carbohydrate groups, e.g., FSH, LH.

What are steroid hormones derived from?

Cholesterol.

What is the synergistic effect of hormones?

When two or more hormones work together to produce a particular result, e.g., norepinephrine and epinephrine increasing cardiac rate.

What is a complementary synergistic effect?

When different hormones contribute to a common effect, such as prolactin, oxytocin, and estrogen stimulating milk production.

What is a permissive effect of hormones?

When one hormone enhances the responsiveness of a target organ to a second hormone, e.g., estradiol inducing progesterone receptors.

What is an antagonistic effect in hormone action?

When one hormone inhibits the effect of another hormone, e.g., high estrogen levels inhibiting prolactin action.

How do endocrine glands differ from exocrine glands?

Endocrine glands lack ducts and secrete hormones directly into the bloodstream, while exocrine glands have ducts.

What are the roles of hypothalamus in the endocrine system?

Controls hormone release from the pituitary gland.

What are the two main divisions of the pituitary gland?

Anterior pituitary and posterior pituitary.

What hormones are released by the anterior pituitary?

GH, PRL, TSH, ACTH, FSH, LH.

What cells secrete growth hormone (GH)?

Somatotropic cells.

What hormones do mammotropic cells secrete?

Prolactin (PRL).

What stimulates the release of thyroid-stimulating hormone (TSH)?

Thyrotropin-releasing hormone (TRH) from the hypothalamus.

What stimulates release of adrenocorticotropic hormone (ACTH)?

Corticotropin-releasing hormone (CRH) from the hypothalamus.

What hormone is secreted by the adrenal cortex?

Cortisol.

What effects do epinephrine and norepinephrine have when released by the adrenal medulla?

Enhance the fight or flight response by increasing respiratory rate and cardiac output.

Where are receptors for lipophilic hormones typically located?

In the cytoplasm or nucleus of target cells.

How do water-soluble hormones exert their effects?

Through second messenger systems, as they cannot enter the cell directly.

What is a homodimer?

A complex formed by two identical receptor molecules at hormone response elements.

What type of receptor do hydrophilic hormones use?

G protein-coupled receptors on the cell membrane.

What role does insulin play in glucose metabolism?

Insulin decreases blood sugar levels by promoting glucose uptake and storage.

What hormone is released by alpha cells in the pancreas?

Glucagon.

What does glucagon do when blood glucose levels are low?

Stimulates the liver to release glucose through glycogenolysis.

Which metabolic processes does glucagon stimulate?

Glycogenolysis, gluconeogenesis, and lipolysis.

How does insulin prevent hyperglycemia?

By signaling body cells to take up glucose and promoting its storage as glycogen.

What are some effects of catecholamines during stress?

Increase blood glucose, heart rate, and energy availability.

What are the major hormones produced by the adrenal cortex?

Mineralocorticoids, glucocorticoids, and androgens.

What does aldosterone do?

Regulates sodium and potassium balance and helps control blood pressure.

What is the function of cortisol?

Regulates metabolism and helps the body respond to stress.

Where are follicular cells of the thyroid gland located?

They are located in the thyroid follicles, synthesizing and secreting T3 and T4.

What is the primary action of thyroid hormones?

To increase metabolic rate and regulate growth and development.

What is T3's role in basal metabolic rate (BMR)?

T3 helps to set and maintain BMR by regulating cellular respiration.

What is hypothyroidism and its consequences?

A deficiency in thyroid hormone that can lead to low metabolic rate, weight gain, and fatigue.

What is hyperthyroidism?

An overproduction of thyroid hormones causing increased metabolic rate, weight loss, and high energy levels.

What hormone do beta cells of the pancreas secrete in response to high blood sugar?

Insulin.

What is the normal fasting blood glucose level?

70-100 mg/dL.

What does a rise in glucose levels stimulate in the pancreas?

Secretion of insulin by beta cells.

What happens to blood glucose levels if insulin is absent?

Blood glucose levels can rise to dangerously high levels, leading to hyperglycemia.

What are the symptoms of diabetes mellitus?

Chronic high blood glucose, increased thirst, frequent urination, and fatigue.

What causes Type I diabetes mellitus?

Insufficient insulin secretion due to autoimmune destruction of beta cells.

What factors contribute to Type II diabetes?

Insulin resistance, often associated with obesity and inactivity.

What does the adrenal medulla secrete during stress?

Epinephrine and norepinephrine.

What is the function of glucocorticoids?

To manage metabolism and immune response during stress.

Where is the pituitary gland located?

In the hypophyseal fossa of the sella turcica.

What is the function of the infundibulum?

Connects the pituitary gland to the hypothalamus.

What stimulates the secretion of ADH?

Increased plasma osmolality.

What is the role of oxytocin during childbirth?

Stimulates contractions of the uterus.

What two hormones are produced in the posterior pituitary?

ADH and oxytocin.

How does insulin facilitate glucose uptake in cells?

By promoting the translocation of GLUT4 transporters to the cell membrane.

What is the function of peptide hormones such as insulin?

To regulate functions such as glucose metabolism and growth.

What causes the secretion of glucagon by alpha cells?

Decreased blood glucose levels.

What is the ultimate effect of thyroid hormones on the body?

To regulate metabolism and overall energy homeostasis.

What occurs during the process of gluconeogenesis?

Conversion of non-carbohydrates to glucose.

What hormone increases during fasting to help regulate blood glucose levels?

Cortisol.

What is a goiter?

Excessive growth of the thyroid due to high TSH levels.

Name a common cause of hypothyroidism.

Iodine deficiency.

What are common treatments for hyperthyroidism?

Antithyroid medications, radioactive iodine, and surgery.

How does T3 affect BMR?

Increases BMR by facilitating cellular respiration and energy expenditure.

What is the primary cardiovascular effect seen in hypothyroidism?

Bradycardia (slow heart rate).

What is the role of TRH in regulating thyroid function?

Stimulates the release of TSH from the anterior pituitary.

What are chromaffin cells?

Cells in the adrenal medulla that secrete catecholamines.

What is the significance of hormone response elements?

They are sequences of DNA that hormone-bound receptors attach to, activating gene transcription.

What are the symptoms of hypothyroidism?

Fatigue, weight gain, cold intolerance, and depression.

What does a high level of cortisol in response to stress indicate?

Activation of the body's fight or flight response.

What are the main components of hormone signaling through lipophilic hormones?

Binding to nuclear receptors and initiating gene transcription.