Lecture 17 Flashcards
The Endocrine system
What is the main function of the endocrine system?
The endocrine system coordinates and controls various body functions by releasing hormones that regulate processes like metabolism, reproduction, growth, and stress responses.
How does the endocrine system work alongside the nervous system?
The endocrine system works with the nervous system to send signals throughout the body, but while the nervous system acts quickly, the endocrine system has longer-lasting effects through hormones.
What are the primary roles of hormones in the body?
Hormones regulate functions such as metabolism, reproduction, growth, development, and responses to stress and injury.
How do hormones trigger responses in target cells?
Hormones bind to receptors on target cells, which may lead to changes in gene expression or protein synthesis, causing the cell to respond accordingly.
How does the speed of endocrine signals compare to nervous system signals?
Endocrine signals are slower compared to nervous system signals, but they have longer-lasting effects.
What type of effects do hormones typically have on the body?
Hormones often have long-term effects, such as regulating growth, metabolism, and homeostasis, and they can influence processes like mood and immune function.
What is the source of steroid hormones?
Steroid hormones are derived from cholesterol and are lipid-soluble.
Where do steroid hormones typically bind to trigger their effects?
Steroid hormones bind to intracellular receptors in the cytoplasm or nucleus of target cells.
What is the process of steroidogenesis?
Steroidogenesis begins with the formation of pregnenolone, and different steroid-secreting cells modify pregnenolone using specific enzymes to produce different steroid hormones.
What are peptide hormones made of?
Peptide hormones are composed of amino acids and are typically proteins.
How do peptide hormones interact with cells?
Peptide hormones bind to receptors on the cell membrane because they are large and water-soluble.
Can you give an example of a peptide hormone?
An example of a peptide hormone is antidiuretic hormone (ADH), which helps regulate water balance in the body.
What type of molecules are amine hormones derived from?
Amine hormones are derived from amino acids.
Can you name an example of an amine hormone and its source?
Melatonin is an amine hormone derived from tryptophan in the pineal gland.
What do endocrine cells do in the body?
Endocrine cells secrete hormones into the bloodstream, which then travel to target cells to induce specific responses.
How do neurosecretory cells differ from other endocrine cells?
Neurosecretory cells release neurohormones in response to action potentials, while other endocrine cells release hormones without needing action potentials.
What is the difference between paracrine and autocrine signaling?
Paracrine signaling involves signals that act on nearby cells, while autocrine signaling affects the same cell that produced the signal.
How do these signals affect neighboring cells or the same cell?
Paracrine signals activate receptors on neighboring cells, and autocrine signals activate receptors on the same cell, often triggering local cellular responses like mitosis.
What triggers the RAAAS pathway in the kidneys?
The RAAAS pathway is activated when systemic blood pressure is low, which is detected by juxtaglomerular cells.
How does Angiotensin II help regulate blood pressure?
Angiotensin II constricts blood vessels, stimulates the release of ADH and aldosterone, and enhances sodium and water reabsorption to raise blood pressure.
What is the role of ADH and Aldosterone in this pathway?
ADH increases water reabsorption in the kidneys, while aldosterone increases sodium and water reabsorption, both helping to raise blood pressure.
What is the function of ADH in the body?
ADH regulates water balance by increasing water reabsorption in the kidneys, thus reducing urine output.
How does ADH help maintain water balance in the kidneys?
ADH promotes the insertion of aquaporins in the collecting ducts of the kidneys, allowing more water to be reabsorbed back into the bloodstream.
What are the two main types of insect metamorphosis?
The two main types are gradual metamorphosis (e.g., cockroaches) and punctuated metamorphosis (e.g., butterflies).
What is an instar, and why is it important in insect development?
An instar is a developmental stage between molts. Each instar represents a growth phase before the next molt.
What are the three principal hormones that control insect metamorphosis?
The three principal hormones are Prothoracicotropic hormone (PTTH), Ecdysone, and Juvenile Hormone (JH).
How does Prothoracicotropic hormone (PTTH) affect insect development?
PTTH triggers the release of Ecdysone, which induces molting and metamorphosis.
What role does Juvenile Hormone (JH) play in insect metamorphosis?
JH maintains juvenile characteristics. High JH levels cause larvae to grow larger, while low levels during the last instar allow for the development of adult or pupal structures.
