Hormones Flashcards
What are pheromones?
They are chemical signals that are released into the air and that communicate info from one individual to another and act through the olfactory system
Ex: synchronization of menstruation among human females living together in dorms; dogs (and other animals) marking territory by urination; mate attraction in arthropods
Simple Endocrine Pathway
- stimulus
- receptor protein
- endocrine cell
- blood vessel
- target effectors
- response
Simple Neuroendocrine Pathway
- stimulus
- sensory neuron
- hypothalamus/posterior pituitary
- neurosecretory cell
- blood vessel
- target effectors
- response
Hormone Cascade Pathway
- stimulus
- sensory neuron
- hypothalamus
- neurosecretory cell
- blood vessel
- endocrine cell
- blood vessel
- target effectors
- response
Pituitary gland is the…
“Master Gland”
-specifically posterior pituitary > hormones are synthesized in hypothalamus but released from nerve endings in posterior pituitary
Antidiuretic Hormon Pathway
-Homeostasis: blood osmolarity
-Stimulus: Increase in blood osmolarity (after sweating profusely)
-Osmoreceptors in hypothalamus trigger release of ADH
-Thirst AND kidney increases permeability
-Drinking water reduces blood osmolarity to set point and H2O reabsorption prevents further osmolarity increase
-Back to homeostasis
ADH is blocked by…
ETHANOL
-H2O cannot be reabsorbed
-leads to dehydration
What are tropic hormones?
Hormones that are released from the anterior pituitary that regulate the activity of other endocrine glands
What are non-tropic hormones?
Hormones that directly influence tissues that are not endocrine glands
AP hormones (tropic effects only)
-follicle-stimulating hormone (FSH) > testes/ovaries
-luteinizing hormone (LH) > testes/ovaries
-thyroid-stimulating hormone (TSH) > thyroid
-adrenocorticotropic hormone (ACTH) > adrenal cortex
AP hormones (non-tropic effects only)
-prolactin > mammary glands
-melanocyte-stimulating hormone > melanocytes
-endorphin > pain receptors in the brain
AP hormones (tropic and non-tropic effects)
growth hormone > liver and bones
Prolactin
-mammalian females: stimulates breast development and milk production
-mammalian males: helps regulate the level of testosterone secretion by the testes
-birds: regulates fat metabolism and reproduction
-amphibians: regulates metamorphosis
-fishes: regulates salt and water balance
Endorphins
-body’s natural opiates
-bind to pain receptors in brain and dull pain reception
-“runner’s high”
-morphine, opium, heroin are mimics of endorphins
Growth hormone (tropic and non-tropic effects)
-Tropic: liver cells > release of insulin-like growth factors (IGFs) > stimulation of bone and cartilage growth
-Non-tropic: all cells > amino acid uptake
Effect of underproduction of growth hormone in childhood
pituitary dwarfism
Effect of overproduction of growth hormone in childhood
gigantism
Thyroid, TRH, TSH, and thyroxine
-TRH = thyrotropin-releasing hormone; exposure to cold stimulates TRH
-TSH = thyroid-stimulating hormone aka thryotropin
-thyroxine: increases basal metabolic rate and turns off TRH production (negative feedback)
-Responses: upregulation of basal cell metabolism, stimulation of fat breakdown and protein synthesis, and heat
What are the two forms of thyroxine?
T3 and T4
What is the composition of T3 and T4?
T3: tyrosine and 3 iodine atoms
T4: tyrosine and 4 iodine atoms
What does the thyroid produce mostly? T3 or T4?
T4
What happens to thyroxine when there’s iodine deficiency?
Leads to production of inactive thyroxine, which cannot turn off production of TRH by negative feedback > thyroid cannot stop making inactive thyroxine and works too hard and swells
What happens when the thyroid cannot stop making inactive thyroxine?
-called Hypothyroidism
-symptoms: goiter (thyroid swells and neck has bulge), low metabolism, intolerance of cold, general physical and mental sluggishness
-children: hypothyroidism causes cretinism
What causes the thyroid to produce too much active thyroxine?
-aka Hyperthyroidism
-Negative feedback mechanism fails even though blood levels of thyroxine are high
-Graves’ Disease: an autoimmune disease in which an antibody to the TSH receptor is produced that activates the secretion of thyroxine (agonist to receptor)