Endocrinology Flashcards
chemical substance that is produced and secreted into the blood by an organ or tissue and that has a specific effect on a target tissue located away from the site of its origin.
Hormone*
Prostaglandins?
-influences neighboring cells
-autocrine and paracrine function
-very short half-life
Exocrine or endocrine gland?
Secretory products are
released on to “external surfaces”
* e.g. Sweat, Salivary gland
Exocrine gland
Exocrine or endocrine gland?
-Secretory products into the “blood stream”
-transport them to specific target tissues
Endocrine gland
-Upon reaching the specific target
* Secretary product alters the function of target
cell
❖ Characteristics of endocrine hormones and their effects:
Effects are not on and off but graded…
up or down
❖ Characteristics of endocrine hormones and their effects:
Secretion is not constant but usually occurs in _______.
pulses
-Provocative tests are required (stimulates max release)
❖ Characteristics of endocrine hormones and their effects:
Effects of the hormones continue after…
the hormone is gone
❖ Characteristics of endocrine hormones and their effects:
Hormones don’t act alone. What are some examples?
blood glucose; insulin and glucagon
❖ Characteristics of endocrine hormones and their effects:
Some hormones do similar things at….
different rates
Glucagon & cortisol: increases [glucose]blood, glucagon: rapid & temporary v. cortisol: slow & sustained
❖ Characteristics of endocrine hormones and their effects:
Some hormones accomplish similar results with different…
tissue specificities
-Epi & glucagon on glycogenolysis. Epi: muscle v. Glucagon: best on liver
❖ Characteristics of endocrine hormones and their effects:
Sometimes the tissue determines the _________ of the response.
quality
ex: EPI- glycogenolysis in muscle( increases glucose) & lipolysis in adipose (increases FA)
❖ Characteristics of endocrine hormones and their effects:
Hormone don’t always fit the ________ definition.
classical
ex: e.g. ACTH (mostly released in the adrenal glands but also in the brain)
What are the physiologic functions of hormones?
-Maintenance of
internal milieu
-Production
-Growth and
Development
-Energy Metabolism
How many amino acids are peptides? Proteins?
peptides = <100
proteins = >100
Where does ADH come from?
hypothalamus
Hormone type:
-Water soluble and do not require transport proteins
-short half-life
-synthesized from amino acids
➢Protein /Peptide Hormones
e.g. insulin, glucagon
Hormone type:
Synthesized from cholesterol
* Lipid soluble and require transport proteins
– Only free-form is biologically-active
* Long half life
Steroid hormones
e.g. testosterone, aldosterone
Hormone type:
derived from tyrosine
Amino acid-based hormones
e.g. Thyroxine, epinephrine (catecholamine)
_____________ stimulates transcription of sodium/potassium ATPase
aldosterone
What causes hormones to have different mechanisms of action?
due to structural and solubility differences.
-large & H2O soluble
➡ tend to remain in the circulation
✴These hormones bind to EXTRACELLULAR RECEPTORS activating a protein cascade
➢ Involves membrane receptor activation & a secondary messenger
Protein-based hormones
Cross membranes –> bind DIRECTLY to their intracellular targets.
✴ Hormone-Receptor complex DIRECTLY activates TRANSCRIPTION.
Steroid hormones: lipophilic
❖ Hormone secretion occurs in _______ or ________ rather than in a continuous,
constant manner
bursts, pulses
Only a small portion of the hormone is removed by the target tissue;
most are cleared by
the liver or kidneys
__________ hormones: actions are specific for another endocrine gland
Tropic
___________ hormones: Directly stimulate target cells to induce
effects.
❖ Non-tropic
__________ hormone: Works on organ or tissues to enhance cellular “growth, differentiation & survival”
Trophic
(bigger word, bigger tissues)
Major function of the anterior pituitary? posterior pituitary?
anterior pituitary- makes hormones
posterior pituitary- storage of hypothalamus hormones.
The hypothalamus is Connected to pituitary via a cluster of nerves & blood vessels called the pituitary _______
stalk
The hypothalamus produces what factors?
releasing factors
(RF) & inhibiting factors (IF).
What is PVN?
paraventricular nucleus
What is SON?
supraoptic nucleus
Composed of nests of different cell types that secrete different hormones
– Hormone secretion is controlled by the hypothalamus (Tropic hormones)
Adenohypophysis (anterior lobe)
Adenohypophysis (anterior lobe):
– Hormones: FLAT PEG?
FSH, LH, ACTH, TSH
Prolactin, Endorphins, GH
Does NOT synthesize any hormones.
– Serves as a storage area for ADH (vasopressin) and Oxytocin –produced by hypothalamus.
Neurohypophysis (posterior lobe)
“Stimulus” of ADH?
- Increased extracellular fluid osmolality
- Declining blood pressure or volume
- Non-specific stimuli: trauma, anxiety, nicotine, barbiturate anesthetics
Vasopressin is primarily synthesized in the _______
SON
-ADH is transported to the P-Pit & stored in axon terminals
“Effect” of ADH?
- ADH increases the water permeability of CD (V2 receptor & cAMP)
- Contracts vascular smooth muscle (V1 receptor, IP3)
-increased aquaporin expression in the nephron
Oxytocin is secreted by the _____.***
PVN
-Short half life (3-5 min)
Where is oxytocin stored/released?
by the posterior pituitary.
Where are the major sites of action of oxytocin?
Smooth muscle
1) Uterus 2) Mammary gland
-Critical role in lactation & during labor
1) stimulates the epithelial cells surrounding the mammary glands
(Milk ejection)
2) Uterine smooth muscle contraction
3) Psychological function: as a neurotransmitter
OXYTOCIN
Stimulus for oxytocin release…
- Suckling: sensory receptor send afferent signal to the CNS generating AP in neurons with nerve endings in the p-Pit which
release oxytocin - Distention of uterus & cervix: during pregnancy & movements of the infant result in transmission of neural signals to the CNS.
Subsequent AP release oxytocin from the p-Pit - Stimulation of the cervix during sexual intercourse also sends signals to release oxytocin from the P-pit
Frequency & force of oxytocin-induced contractions sharply
enhanced in the presence of ___________.
estrogen