Flashcards in Endocrine - Introduction Deck (29)
what are the 4 things that the Endocrine system controls?
1. Development and growth
2. energy regulation (storage & mobilization)
3. internal homeostasis
4. Reproduction (sex, pregnancy, lactation)
borne via bloodstream
acting in local environment
acting on secreting cell
the study of the homeostatic chemical adjustments and other activities that hormones accomplish
what are amino hormones ?
derived from tyrosine
what are peptide and protein hormones?
encoded in genes
what are steroid hormones?
derived from cholesterol
what kind of hormones are epinephrine and norepinephrine?
what kind of hormones are thyroxine (T4) and trioidothyronine (T3)?
how are protein hormones produced?
they are transcribed from genes and translated in the rough ER. They may undergo one or more post-translational modification and are stored in secretory vesicles where they are released upon stimulation by exocytosis
are protein hormones hydrophilic or hydrophobic?
hydrophilic, which means they cannot freely cross membranes
what are some examples of steroid hormones?
can steroid molecules cross membranes?
yes because they are lipophilic
what do steroids bind to when traveling through the blood?
steroid-binding globulins (SBGs)
What are the 3 axes for which the endocrine system acts?
1. HPT - hypothalamic-pituitary-thyroid axis
2. HPA - hypothalamic - pituitary - adrenal axis
3. HPG - hypothalamic - pituitary - gonadal axis
When do the endocrine axes use positive feedback control instead of negative ?
1. mid-cycle surge of gonadotropins (LH & FSH) stimulated by high level of estrogen
2. oxytocin during parturition and suckling
what is the physiological and clinical significance of pulsatile and hormone secretion?
1. maintains target organ sensitivity
2. prevents down-regulation of receptors
what are 3 types of second messenger systems?
1. cAMP or cGMP
2. phospholipids diacylglycerol and inositol triphosphate (DAG and IP3)
what converts ATP to cAMP?
what does phospholipase C convert PIP2 into?
DAG and IP3
how do cells down-regulate receptors?
- after hormone binding, receptors are internalized (coated pits)
which hormones act via intracellular receptors?
2. thyroid hormones
too little hormone secreted
too much hormone is secreted
what is secondary hyposecretion?
gland is normal but too little hormone is secreted due to deficiency of its tropic hormone
what is primary hyposecretion?
too little hormone is secreted due to abnormality within gland
too much hormone is secreted due to abnormality within gland (ex. hormone secreting tumours)