Endocrinology Flashcards
(31 cards)
What is endocrinology?
The study of the endocrine system and hormones involved in regulating various physiological processes.
Why do animals and humans need an endocrine system?
To enable communication between cells, coordinate homeostasis, regulate growth, reproduction, and adapt to environmental changes.
What are hormones?
Chemical messengers secreted by endocrine glands that travel in the bloodstream to target cells with specific receptors.
Name the three classes of hormones.
1) Proteins/Peptides (e.g. growth hormone), 2) Steroids (e.g. cortisol), 3) Modified amino acids (e.g. adrenaline, thyroid hormones).
What is the difference between hydrophilic and hydrophobic hormones?
Hydrophilic hormones bind to cell surface receptors; hydrophobic hormones pass through the membrane to bind intracellular receptors.
How do peptide hormones work?
They bind to extracellular receptors and activate intracellular signaling via second messengers.
How do steroid hormones work?
They diffuse through membranes and bind to intracellular receptors, often altering gene expression.
What factors influence circulating hormone levels?
Rate of secretion, metabolism by tissues, presence of serum binding proteins.
What are the three mechanisms regulating hormone secretion?
1) Physiological changes (e.g. glucose for insulin), 2) Endogenous rhythms (ultradian, circadian, infradian), 3) Feedback mechanisms.
What is negative feedback in the endocrine system?
A control mechanism where the output reduces the original stimulus, maintaining homeostasis.
What are the main types of endocrine dysfunction?
Hyposecretion, hypersecretion, ectopic hormone secretion.
What are common causes of hyposecretion?
Genetic, dietary, auto-immune, cancer, iatrogenic, idiopathic.
How is hyposecretion treated?
Hormone replacement—steroids orally, protein hormones via injection.
What are causes of hypersecretion?
Tumors, ectopic secretion, immune-related issues, substance abuse.
How is hypersecretion treated?
Surgery, irradiation, hormone-blocking drugs.
What is the role of the pituitary gland?
It is the ‘conductor’ of the endocrine system, connecting the brain with peripheral hormone targets.
What does the hypothalamus/pituitary system regulate?
Growth, metabolism, stress, reproduction, lactation, water/salt balance, feeding, and birth.
What are the hormones of the adrenal gland?
Adrenaline (medulla), cortisol (glucocorticoid), aldosterone (mineralocorticoid).
What are effects of cortisol?
Stress adaptation, glucose mobilization, anti-inflammatory actions.
What does the HPT axis regulate?
Thyroid hormones which influence metabolic rate, heart rate, CNS activity, and growth.
What does insulin do?
Promotes glucose uptake and storage; an anabolic hormone.
What does glucagon do?
Mobilizes fuels, increases glucose via glycogenolysis and gluconeogenesis.
How do insulin and glucagon interact?
Insulin dominates in fed state, glucagon in fasting; they act reciprocally.
What is diabetes mellitus?
A disorder with impaired insulin production or action, causing elevated blood glucose.
