intro to endocrine system - HOS

endocrine system

a system of glands and tissues that release chemical messengers (hormones) into the blood stream which act to alter activity in target tissues located at a distant site

pituitary gland

growth hormone stimulates growth

thyroid gland

hormones regulate metabolic rate and calcium

adrenal gland

stress hormones - cortisol and adrenaline

how does adipose tissue/leptin work

increased fat stores/nutrients → leptin → suppress appetite

3 major classes of hormones

peptide, steroid, amino acid

peptide hormones 2 examples

insulin, glucagon

steroid hormones 2 examples

testosterone, oestradiol

amino acid derivatives 2 examples

thyrroid hormone, adrenaline

4 main hormone receptor types

g-protein linked, steroid hormone, tyrosine kinase, ion channel

g-protein linked receptors

receptors for adrenaline

steroid hormone receptor

receptors for adrenaline

tyrosine kinase receptor

receptors for insulin/GF

ion channel receptors

nicotinic receptors (ACh)

nuclear receptors - steroids

lipophilic

nuclear receptors - thyroid hormones

membrane carrier

steroid hormone receptors

group of hormones all synthesis from cholesterol, includes male and female sex hormones

tyrosine kinase receptors

hormones that act through these receptors are peptide or protein hormones, often tend to be involved in tissue growth and repair

ion channel receptor

receptor structure itself is an ion channel

regulation of hormone release

control of release by tropic hormones and nervous system

regulation of hormone concentration in blood

hormones bound to plasma proteins

regulation of target cell sensitivity - activation of the target cell depends on

density of receptors, coupling of receptors to second messenger pathways

regulation of target cell sensitivity - tissue sensitivity can be regulated by

up-regulation (gain receptors in response to hormone), down-regulation (lose receptors in response to the hormone)

synergism

hormones act together

antagonism

opposing action of another hormone

permissiveness

can only act with another hormone present