Ch. 5: The Endocrine System Flashcards
What are peptide hormones?
- derived from larger precursor proteins that are cleaved during posttranslational modification
- modified by the golgi that activates the hormones
- charged (polar) and cannot pass through the plasma membrane so binds to an extracellular recetor (first messenger) which triggers a second signal (second messenger), —- signal cascade that can induce amplification of the signal
- rapid onset of effects but short lived
- since polar can travel freely in the blood and do not need a special carrier
What are steroid hormones?
- derived from cholesterol
- produced by gonads and adrenal cortex
- nonpolar and can easily cross teh cell membrane
- intracellular or intranuclear receptors
- after binding the steroid hormone-receptor complex undergoes conformational changes and the receptor can bind directly DNA
- increased or decreased transcription of particular genes
- slower and longer lived effect than peptide hormones since there is gene regulation
What are amino acid-derivative hormones?
- epinephrine, norepinephrine, triiodyothyronine, thyroxine
- derived from one or two amino acids with modifications
What are direct hormones?
secreted and act directly on target tissue
major effects on non-endocrine tissues
What are tropic hormones?
require an intermediary to act
major effects on other endocrine tissues
What is the role of the hypothalamus in the endocrine system?
uses tropic hormones to regulate the pituitary gland
can cause whole body effects
What is negative feedback?
occurs when a hormone/product later in the pathway inhibits hormones/enzymes earlier in the pathway
stop production of substances that are already present in sufficient quantities
What is the hpophyseal portal system?
blood vessel system that directly connects the hypothalamus with the anterioir pituitary
The hypothalamus secretes…
How does the anterior pituitary gland respond to GnRH?
FSH and LH
The hypothalamus secretes…
How does the anterior pituitary gland respond to GHRH?
growth hormone (GH)
The hypothalamus secretes…
How does the anterior pituitary gland respond to TRH (thyroid-releasing hormone)?
thyriod-stimulatin hormone TSH
The hypothalamus secretes…
How does the anterior pituitary gland respond to CRF (corticotropin-releasing factor)?
adrenocorticotropic hormone ACTH
The hypothalamus secretes…
How does the anterior pituitary gland respond to prolactin-inhibiting factor (PIF or dopamine)?
inhibit release of prolactin
How does the posterioir pituitary recieve signals?
neurons in the hypothalamus send their axons down the pituitary stalk directly into the posterioir pituitary
the release oxytocin (uterine contractions in labor and lactation) and ADH/vasopressin (increases reabsorption of water in collectin ducts of the kidneys)
What are the products of the anterioir pituitary?
FLAT PEG
Follicle stimulating hormone (FSH)
Luteinizing hormone (LH)
Adrenocorticotropic hormone (ACTH)
Thyriod-stimulating hormone (TSH)
Prolactin
Endorphins
Growth hormone (GH)
FLAT - tropic hormones
PEG - direct hormones
What does FSH do?
promotes development of ovarian follicles and spermatogenesis
What does LH do?
promotes ovulation and testosterone production
What does ACTH do?
promotes synthesis and release of glucocorticoids from adrenal cortex
What does TSH do?
promotes synthesis and release of triiodothyronine and thyroxine from the thyroid