chapter 16: endocrine system Flashcards
What is the endocrine system?
One of the body’s two major control systems that influences metabolic activity using hormones.
How does the endocrine system differ from the nervous system in relation to speed, messenger, and duration of effects?
Endocrine: Uses hormones, slower but long-lasting effects.
Nervous: Uses neurotransmitters, fast but short-lived effects.
How do endocrine glands differ from exocrine glands in terms of secretion method and location?
Endocrine: Secretes hormones directly into the bloodstream (enDO = Direct)
Exocrine: Secretes substances via ducts to external surfaces/body cavities (EXo = External).
What is the function of the pineal gland?
Produces/releases melatonin to regulate sleep-wake cycles.
What is the function of the hypothalamus?
Controls the endocrine system by regulating the pituitary gland and maintaining homeostasis.
What is the function of the pituitary gland?
Known as the “master gland”, it produces hormones that regulate other endocrine glands.
What is the function of the thyroid gland?
Regulates growth, metabolism, energy, and calcium balance using T3, T4, and calcitonin.
What is the function of the adrenal gland?
Produces stress-related hormones (adrenaline, cortisol) and regulates blood pressure & electrolytes.
What is the function of the parathyroid gland?
Maintains calcium, magnesium, and phosphorus levels in the blood and bones.
What is the function of the thymus?
Supports the immune system by producing white blood cells (T-cells).
What is the function of the pancreas?
Produces insulin and glucagon for blood glucose regulation.
What is the function of the gonads (ovaries/testes)?
Produces sex hormones that regulate reproduction and sexual characteristics.
What is autocrine signaling (distance, affected cell)?
Short-distance chemical signals that affect the same type of cell that released them.
What is paracrine signaling (distance, affected cell)?
Short-distance signals that affect different types of nearby cells.
What is endocrine signaling (distance, affected cell)?
Long-distance signals that travel through the bloodstream to target cells in other tissues/organs.
What is synaptic signaling (distance, affected cell)?
Neurotransmitters travel across synapses to target specific nearby cells.
What are peptide hormones made of? Describe their acting speed, solubility, and effect duration.
Made of amino acids (e.g., GH, ACTH), water-soluble, fast-acting, short-lived effects.
What are steroid hormones? made of? Describe their acting speed, solubility, and effect duration.
Derived from cholesterol (e.g., cortisol, estrogen, testosterone), lipid-soluble, slow but long-lasting effects.
What are modified amino acid hormones?
Derived from single amino acids (e.g., prolactin, thyroid hormones, epinephrine).
How do water-soluble hormones work?
Cannot pass through cell membranes, so they bind to surface receptors.
Use second messengers (e.g., cAMP) to amplify signals inside the cell.
How do lipid-soluble hormones work?
Pass through the cell membrane and bind to intracellular receptors.
Directly affect gene transcription and protein synthesis.
Are hormones secreted constantly?
No! They are released in short bursts when needed and regulated by feedback mechanisms.
What are the three types of endocrine stimulation and when are they triggered?
Humoral stimuli: Triggered by blood levels of ions/nutrients (e.g., low calcium → PTH release).
Neural stimuli: Triggered by nervous system signals (e.g., stress → adrenal medulla releases adrenaline).
Hormonal stimuli: Triggered by other hormones (e.g., TRH → TSH → T3/T4 release).
How is hormone secretion regulated?
Negative feedback loop: If hormone levels rise too high, secretion stops (e.g., insulin and blood glucose levels).
