endocrine system Flashcards
endocrine overview
What is the general adaptation syndrome?
A stress response consisting of three phases: Alarm phase, Resistance phase, Exhaustion phase.
What occurs during the exhaustion phase of the general adaptation syndrome?
Homeostasis starts to break down, leading to potential organ failure.
What hormone is released during the resistance phase that affects potassium levels?
Aldosterone.
What is the primary effect of aldosterone?
Sodium retention and potassium dumping.
What is a potential fatal outcome of the exhaustion phase?
Organ failure or organ system failure.
What initiates the G-protein systems with calcium ions?
G-protein activates phospholipase C (PLC).
What are the products of the PLC cascade?
Diacylglyceride (DAG) and inositol triphosphate (IP3).
What does IP3 cause?
Release of intracellular calcium ions.
What is the role of protein kinase C (PKC)?
Activated by calcium ions, causing the opening of calcium ion channels.
How do non-lipid soluble hormones interact with target cells?
They bind to extracellular receptors on the cell surface.
What is a key characteristic of lipid-soluble hormones?
They can diffuse through the phospholipid bilayer.
What is the sequence of events when a lipid-soluble hormone binds to its receptor?
Forms a receptor-hormone complex, enters nucleus, binds to DNA, initiates transcription.
What happens to water-soluble hormones upon entering a target cell?
They bind to surface cell-membrane receptors and initiate a cell-signaling pathway.
What is the main mechanism of hormone regulation?
Negative feedback.
What does humoral stimulation involve?
Change in extracellular fluid affecting hormone release.
What is the dominant hormone during the alarm phase of stress response?
Epinephrine.
What defines the resistance phase of the general adaptation syndrome?
Stress lasting longer than a few hours, conserving glucose for the nervous system.
What are the dominant hormones during the resistance phase?
Glucocorticoids.
What is downregulation?
Decrease in the number of hormone receptors when hormone levels are high.
What is upregulation?
Increase in the number of hormone receptors when hormone levels are low.
What are short chain peptide hormones often produced as?
Prohormones.
What are eicosanoids derived from?
The 20 carbon fatty acid, arachidonic acid.
What are the main types of lipid-derived hormones?
Steroid hormones and eicosanoids.
What is the primary function of endocrine glands?
Secrete their products directly into the blood.
