Week 1Endocrine System Flashcards
(50 cards)
What is a gland?
A gland is any structure or organ that produces a secretion.
What are endocrine glands?
Ductless glands that secrete hormones into the blood or lymph, affecting distant target tissues.
What are exocrine glands?
Glands with ducts that transport secretions to specific local areas (e.g., sweat, salivary, mammary glands).
Which organs have both endocrine and exocrine functions?
Pancreas (enzymes and insulin/glucagon), stomach, and small intestine.
What is the purpose of hormones?
Hormones are chemical messengers that regulate various body functions and maintain homeostasis.
List six general functions of hormones.
- Stimulate exocrine glands, 2. Stimulate endocrine glands, 3. Affect growth and personality, 4. Regulate metabolism, 5. Control muscle and nerve stimulation, 6. Regulate reproductive processes.
What are the three main stimuli for hormone secretion?
- Humoral (chemical levels in blood), 2. Hormonal (stimulation by other hormones), 3. Nervous (nerve signals triggering release).
Give an example of humoral stimulus.
High blood glucose stimulates insulin release from pancreas (negative feedback).
Give an example of hormonal stimulus.
TRH from hypothalamus stimulates TSH from anterior pituitary, which stimulates thyroid hormone release.
Give an example of nervous stimulus.
Sympathetic nervous system stimulates adrenal medulla to release epinephrine and norepinephrine.
What are the four structural categories of hormones?
Amine, Peptide, Protein, Steroid.
How do lipid-soluble hormones function?
They pass through the membrane, bind to intracellular receptors, and initiate gene transcription (e.g., steroid and thyroid hormones).
How do water-soluble hormones function?
They bind to membrane receptors and activate a signal cascade via second messengers like cAMP (e.g., epinephrine, insulin).
Why are steroid hormones’ effects longer-lasting?
They bind to transport proteins and have longer half-lives in the blood (e.g., cortisol: 60-90 min vs epinephrine: ~1 min).
Compare the endocrine and nervous systems by signaling mechanism and speed.
Endocrine uses hormones (slow, long-lasting), nervous uses neurotransmitters (fast, short-duration).
Which system acts faster and which lasts longer?
Nervous system acts faster; endocrine effects last longer.
What connects the hypothalamus and pituitary?
The infundibulum (pituitary stalk).
What is the hypophyseal portal system?
A capillary network allowing hypothalamic hormones to reach the anterior pituitary directly.
List hypothalamic releasing hormones.
CRH, TRH, GnRH, GHRH; also PIH and GHIH as inhibiting hormones.
What hormones are stored and released by the posterior pituitary?
Oxytocin and antidiuretic hormone (ADH), both produced in the hypothalamus.
Which anterior pituitary hormones are non-tropic?
Growth hormone (GH) and prolactin (PRL).
List the tropic hormones from the anterior pituitary.
TSH, ACTH, FSH, LH.
What does GH do?
Promotes protein synthesis, fat metabolism, and tissue growth; stimulated by GHRH, inhibited by GHIH.
What does PRL do?
Promotes milk production in mammary glands; regulated by PRH and PIH.