Endocrine System: Hormones, Glands, and Regulation Principles Study Guide | Quizlet

What is the primary purpose of the endocrine system?

To examine the structures and functions of the endocrine system.

Which glands are compared in terms of hormone release in the endocrine system?

Hypothalamus, pituitary, thyroid, parathyroid, suprarenal, pancreas, ovaries, testes, pineal gland, and thymus.

How do the nervous and endocrine systems coordinate body functions?

The nervous system releases neurotransmitters, while the endocrine system releases hormones.

What is the primary difference between hormones and neurotransmitters?

Hormones circulate through the blood to target cells, while neurotransmitters act locally at synapses.

What are exocrine glands?

Glands that secrete their products into ducts; they do not secrete hormones.

What is the function of endocrine glands?

To secrete hormones directly into the interstitial fluid, which then diffuse into the bloodstream.

Name some organs that contain secreting cells but are not part of the endocrine system.

Hypothalamus, thymus, pancreas, ovaries, testes, kidneys, stomach, liver, small intestine, skin, heart, adipose tissue, and placenta.

What types of hormones are there based on solubility?

Lipid-soluble hormones (steroid hormones, thyroid hormones) and water-soluble hormones (amine hormones, peptide and protein hormones, eicosanoid hormones).

How do lipid-soluble hormones circulate in the blood?

They circulate bound to transport proteins.

What is the role of receptors in hormone activity?

Hormones affect only target cells that possess specific protein receptors for them.

What happens to hormone receptors in the presence of high hormone concentrations?

Receptors may be down-regulated.

What is the mechanism of action for water-soluble hormones?

They bind to receptors on the exterior surface of the target cell.

What is the typical time frame for the action of the endocrine system?

Seconds to hours or days, compared to milliseconds for the nervous system.

What is the primary regulation mechanism for hormone secretion?

Most hormone regulation is achieved via negative feedback.

What are paracrines and autocrines?

Paracrines are local hormones that affect nearby cells, while autocrines act on the same cell that secretes them.

What factors influence how a target cell responds to a hormone?

The hormone's concentration in the blood, the number of hormone receptors on the target cell, and influences from other hormones.

What is a synergistic effect in hormone action?

When some hormones work more effectively in the presence of a second hormone.

What is an antagonistic effect in hormone action?

When some hormones oppose the action of others.

What is the duration of action for hormones compared to neurotransmitters?

Hormones generally have a longer duration of action (seconds to days) than neurotransmitters (milliseconds).

What is the role of the hypothalamus in the endocrine system?

It contains secreting cells that release hormones and regulate other endocrine glands.

What is the significance of the adrenal glands in the endocrine system?

They are one of the key endocrine glands that secrete hormones involved in stress response.

What is the relationship between hormone concentration and receptor regulation?

High hormone concentrations can lead to down-regulation of receptors, while low concentrations can lead to up-regulation.

What is the primary function of the pituitary gland?

To release hormones that regulate various endocrine functions and other glands.

What is the role of the thyroid gland?

To regulate metabolism through the secretion of thyroid hormones.

How do hormones affect metabolic actions?

They can alter the rate of metabolic actions in target cells.

What is the function of the pancreas in the endocrine system?

To secrete hormones like insulin and glucagon that regulate blood sugar levels.

What is the role of the pineal gland?

To secrete melatonin, which regulates sleep-wake cycles.

What connects the hypothalamus and pituitary gland?

The infundibulum

What percentage of the pituitary gland's weight is made up by the anterior lobe?

75%

What are the two main hormones released by the posterior lobe of the pituitary gland?

Oxytocin (OT) and Antidiuretic hormone (ADH)

How does the hypothalamus control the release of hormones by the pituitary gland?

By secreting releasing and inhibiting hormones that travel via the hypophyseal portal system

What is the role of growth hormone-inhibiting hormone (GHIH)?

It suppresses the secretion of growth hormone (GH)

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

Thyrotropin-releasing hormone (TRH)

What is the function of gonadotropin-releasing hormone (GnRH)?

It stimulates the secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

What hormone does the anterior pituitary secrete that is responsible for milk production?

Prolactin (PRL)

What is the primary hormone secreted by somatotrophic cells?

Growth hormone (GH)

What is the function of adrenocorticotropic hormone (ACTH)?

It stimulates the adrenal cortex to release cortisol

What triggers the release of oxytocin during childbirth?

Stretch placed on the cervix

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

It decreases urine output and regulates blood osmotic pressure

What effect does an increase in blood volume have on ADH secretion?

It causes a decrease in ADH secretion

What effect does a decrease in blood volume have on ADH secretion?

It causes an increase in ADH secretion

What is the shape and location of the thyroid gland?

Butterfly-shaped, located inferior to the larynx and anterior to the trachea

What hormones are produced by follicular cells of the thyroid gland?

Thyroxine (T4) and triiodothyronine (T3)

What hormone is produced by parafollicular cells in the thyroid gland?

Calcitonin

What are the principal actions of thyroid hormones?

Increase basal metabolic rate, maintain body temperature, stimulate protein synthesis, and increase ATP production

What is the process for synthesizing thyroid hormones?

An 8-step process stimulated by TSH

What is the role of thyrotropin-releasing hormone (TRH) in thyroid hormone regulation?

It stimulates the synthesis and release of thyroid hormones

What is the function of melanocyte-stimulating hormone (MSH)?

It influences pigmentation in the skin

What is the role of negative feedback loops in hormone secretion?

They control the secretions of thyrotrophs, gonadotrophs, and corticotrophs

What triggers the release of growth hormone (GH)?

Growth hormone-releasing hormone (GHRH)

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

They regulate metabolism and energy production

What is the significance of the hypophyseal portal system?

It allows hypothalamic hormones to directly influence the anterior pituitary

What is the relationship between the hypothalamus and the posterior pituitary?

The posterior pituitary stores and releases hormones produced by the hypothalamus

What hormone does the hypothalamus release to stimulate the thyroid gland?

Thyrotropin-releasing hormone (TRH)

What hormone is secreted by the anterior pituitary to stimulate the thyroid?

Thyroid-stimulating hormone (TSH)

What are the two types of cells found in the parathyroid glands?

Chief cells and Oxyphil cells

What hormone is produced by chief cells in the parathyroid glands?

Parathyroid hormone (PTH)

What is the function of calcitonin?

It works with PTH and calcitriol to regulate calcium homeostasis.

Where are the suprarenal glands located?

On top of each kidney

What are the two main regions of the suprarenal glands?

The outer cortex and the inner medulla

What hormones are secreted by the zona glomerulosa of the adrenal cortex?

Mineralocorticoids

What is the major mineralocorticoid secreted by the adrenal gland?

Aldosterone

What regulates the secretion of aldosterone?

The renin-angiotensin-aldosterone (RAA) pathway

What are glucocorticoids primarily responsible for?

Controlling glucose homeostasis and stress responses

What is the major androgen secreted by the suprarenal cortex?

Dehydroepiandrosterone (DHEA)

What hormones do chromaffin cells in the adrenal medulla secrete?

Epinephrine (adrenaline) and norepinephrine (noradrenaline)

What is the primary function of pancreatic islets?

To secrete hormones such as insulin and glucagon

What type of cells in the pancreas secrete glucagon?

Alpha (A) cells

What type of cells in the pancreas secrete insulin?

Beta (B) cells

What hormone is produced by the ovaries?

Estrogens (estradiol and estrone), progesterone, relaxin, and inhibin

What hormone is primarily produced by the testes?

Testosterone

What hormone does the pineal gland secrete?

Melatonin

What is the role of thymosin produced by the thymus?

To promote maturation of T cells in the immune system

What is the function of somatostatin secreted by pancreatic delta cells?

To inhibit the secretion of other hormones

What is the function of pancreatic polypeptide secreted by F cells?

To regulate the secretion of pancreatic digestive enzymes

What is the primary role of the adrenal cortex?

To produce hormones that regulate metabolism, immune response, and blood pressure

What is the function of the adrenal medulla?

To secrete hormones that prepare the body for 'fight-or-flight' responses

What is negative feedback in the context of hormone regulation?

A process where the output of a system inhibits its own production

What is the significance of the RAA pathway?

It regulates blood pressure and fluid balance through aldosterone secretion

What hormones are produced by the ovaries?

Estradiol, estrone, progesterone, relaxin, and inhibin

What hormone is produced by the skin and plays a role in vitamin D synthesis?

Cholecalciferol

What is the principal action of gastrin?

Promotes secretion of gastric juice and increases movements of the stomach.

What hormone stimulates the release of insulin from pancreatic beta cells?

Glucose-dependent insulinotropic peptide (GIP)

What does secretin stimulate?

Secretion of pancreatic juice and bile.

What is the role of cholecystokinin (CCK)?

Stimulates secretion of pancreatic juice, regulates bile release, and causes a feeling of fullness after eating.

What hormone does the placenta produce to maintain pregnancy?

Human chorionic gonadotropin (hCG)

What are the functions of estrogens and progesterone during pregnancy?

Maintain pregnancy and help prepare mammary glands for milk secretion.

What hormone increases blood pressure by causing vasoconstriction?

Renin

What is the function of erythropoietin (EPO)?

Increases rate of red blood cell formation.

What is calcitriol and where is it synthesized?

Active form of vitamin D; synthesis begins in the skin, continues in the liver, and ends in the kidneys.

What is the action of atrial natriuretic peptide (ANP)?

Decreases blood pressure.

What hormone does adipose tissue produce that suppresses appetite?

Leptin

What are eicosanoids derived from?

The 20-carbon fatty acid arachidonic acid.

What is the role of epidermal growth factor (EGF)?

Stimulates proliferation of epithelial cells, fibroblasts, neurons, and astrocytes.

What does platelet-derived growth factor (PDGF) stimulate?

Proliferation of neuroglia, smooth muscle fibers, and fibroblasts; plays a role in wound healing.

What is the function of nerve growth factor (NGF)?

Stimulates growth of ganglia in embryos and maintains the sympathetic nervous system.

What is the first stage of the stress response?

The fight-or-flight response.

What is eustress?

Helpful, everyday stress that prepares us to meet challenges.

What is distress?

Harmful stress that may be damaging.

What happens during the resistance reaction in the stress response?

It lasts longer than the fight-or-flight response.