Endocrine System Introduction Quiz

When hormone levels are high, the number of receptors on cells decreases. This reduces the cell's sensitivity to the hormone and helps maintain balance.

When hormone levels are low, the number of receptors on cells increases. This makes the cell more sensitive to the hormone.

These are located on the cell surface and bind to water-soluble hormones like peptides and proteins.

These are located inside the cell and bind to fat-soluble hormones like steroids.

Located inside the nucleus, these receptors bind to thyroid and steroid hormones to directly regulate gene expression.

These act like messengers inside the cell, relaying signals from hormone-receptor interactions to activate cellular responses.

This system uses cyclic AMP (cAMP) as a second messenger. It's activated by hormones like ACTH, FSH, LH, TSH, MSH, Ang II, and ADH (acting on V2 receptors).

This system utilizes calcium ions and phosphoinositols as second messengers. Important hormones in this system include ADH (acting on V1 receptors), Angiotensin II, catecholamines (alpha-receptors), GnRH, GHRH, oxytocin, and TRH.

Hormones are chemical messengers secreted by specialized cells, often organized into glands. They act on target cells to regulate physiological, metabolic, behavioral, and morphological processes. They are released in small quantities and work by modulating existing biochemical reactions rather than initiating new ones.

Hormones are released in small quantities and act on specific target cells. Their effects are mediated by changes in cellular activity, such as gene expression or enzyme activation.

Autocrine signaling refers to a cell releasing a substance that acts on itself. Intracrine signals, on the other hand, don't leave the cell and act within the same cell.

Paracrine signaling occurs when a cell releases a substance that acts on neighboring cells.

Endocrine signaling involves a cell releasing a substance into the bloodstream, which travels to distant target cells.

The endocrine system works in concert with the nervous system and immune system to maintain body homeostasis. It helps regulate various bodily functions and contributes to overall well-being.

The endocrine system secretes various hormones, including those produced by brain regions like the hypothalamus and pituitary gland, as well as those synthesized by organs like the heart, kidneys, liver, skin, and digestive tract.

The same substance can act as both a hormone and a neurotransmitter, depending on the context. For instance, CCK functions as a hormone in the digestive system and as a neurotransmitter in the brain.

Receptors that directly act as enzymes or are linked to enzymes. When activated, they trigger a chain of intracellular events, like phosphorylation by kinases.

A hormone that activates enzyme-linked receptors. Its binding initiates a cascade of phosphorylation events, leading to various cellular responses.

A signaling pathway where a hormone binds to a receptor, activating a G-protein. This results in the production of cAMP, influencing downstream cellular functions.

Proteins that bind to GTP and are involved in the adenylate cyclase-cAMP system. They can either stimulate (Gs) or inhibit (Gi) the production of cAMP.

A key enzyme in the adenylate cyclase-cAMP system. It catalyzes the conversion of ATP to cAMP, amplifying the hormone's signal.

A second messenger molecule synthesized in the adenylate cyclase-cAMP system. It plays a critical role in various cellular functions, including gene expression and muscle contraction.

A signaling pathway that utilizes the hydrolysis of phosphatidyl inositol 4,5 biphosphate to produce two secondary messengers: IP3 and diacylglycerol.

A secondary messenger produced by the phosphatidyl inositol system. It binds to receptors on the sarcoplasmic reticulum, triggering calcium release.

A signal molecule secreted by endocrine glands or other tissues that travels through the bloodstream to target cells and tissues, where it exerts a specific effect.

The free form of a hormone is unbound to transport proteins in the bloodstream and readily available to act on target cells. While the bound form is attached to transport proteins, serving as a reservoir and regulating hormone release.

Peptidic hormones are water-soluble proteins, like insulin. Steroid hormones are fat-soluble, like testosterone. Amine hormones are derived from amino acids, like adrenaline. Thyroid hormones are fat-soluble, like thyroxine.

The time it takes for the concentration of a hormone in the blood to decrease by half. It varies depending on the hormone type and its metabolism.

Steroid hormones bind to receptors inside the cell, often in the nucleus. Their actions typically involve gene regulation. Peptidic hormones bind to receptors on the cell surface, often triggering second messenger pathways.

The body's internal 'timetable', influencing hormonal release and other biological processes. Circadian rhythms are daily cycles, while others occur over longer periods.

Feedback mechanisms regulate hormone secretion. Negative feedback reduces hormone production when levels are high, while positive feedback amplifies hormone production.

Hormone secretion can be influenced by the nervous system. For example, stress can trigger the release of adrenaline.

Hormones play a crucial role in maintaining homeostasis, which is the body's ability to maintain a stable internal environment.

Hormones are discovered, synthesized, measured, and investigated in new ways, thanks to advancements in various fields like neuroscience, immunology, cell and molecular biology, physics, chemistry, genetics, and cybernetics.

Examples include insulin treatment for diabetes and oral contraceptives for birth control.

The discovery of insulin and its use in treating diabetes was a major breakthrough in medical history.

Oral contraceptives, which contain synthetic hormones, have revolutionized birth control methods.

Brown-Séquard's self-experimentation with animal extracts led to the early exploration of hormone replacement therapies.

Murray's administration of thyroid extract marked a significant advance in the treatment of thyroid disorders.

Parvicellular neurosecretory cells in the hypothalamus are stimulated by neurotransmitters like norepinephrine, dopamine, and serotonin to release hormones. This is a vital mechanism for regulating hormone production.

Magnocellular neurosecretory cells in the hypothalamus are stimulated by acetylcholine and inhibited by norepinephrine, allowing for precise control over hormone release.

A biological system where a hormone's release is controlled by the concentration of another hormone. This regulation helps maintain hormonal balance.

A common type of endocrine feedback where a high concentration of a hormone inhibits the release of another hormone, preventing excessive levels and promoting stability.

A less common type of endocrine feedback where a hormone stimulates its own production, amplifying its effects and leading to a rapid increase in its concentration.

The number of receptors on target cells can decrease when a high concentration of a hormone exists, reducing sensitivity to that hormone.

The relationship between levels of a substrate (like calcium or glucose) and the release of a hormone.

A system that maintains a specific parameter at a constant level through feedback mechanisms.