the endocrine system Flashcards
what is endocrine signalling
hormones are secreted into the circulatory system to act on distant target cells
what is intracrine signalling
signalling molecules released act within the same cell, are never releaed outside the cell
what is autocrine signalling
signalling molecules released by the cell act on the same cell, but are released externally
how many major endocrine glands are there in mammals
9
how many hormones are there in mammals
> 70
what are the 4 types of hormone, which are amines, and are they hydrophillic or phobic
peptides - hydrophilic
catecholamines (amine) - hydrophilic,
thyroid hormone (amine) - hydrophobic,
steroids - hydrophobic
how are peptides transported and what is their receptor
transport - none, free hormone
receptor - target cell surface
how are catecholamines transported and what is their receptor
transport - partly bound to plasma proteins
receptor - target cell surface
how are thyroid hormones transported and what is their receptor
transport - mostly bound to plasma proteins
receptor - intracellular target
how are steroids transported and what is their receptor
transport - mostly bound to plasma protein
receptor - intracellular target
what are peptide proteins and what is their lifecycle
large precursor proteins
synthesised, processed, and packaged into secretory granules by golgi complex
stored and then exocytosis
what are amine hormones derived from
tyrosine
where are catecholamines stored
chromaffin granules
what is the life cycle of thyroid hormone
thyroglobulin synthesised and secreted in to extracellular colloid
combined with iodine, reabsorbed by endocytosis and secreted
what are steroids derived from and how
cholesterol precursor via enzymatic reactions
when are steroids secreted and how
immediately by diffusion
can hormones be secreted by multiple glands
yes
can glands secrete multiple hormones
yes
what is the importance of hormone receptors
ensure specificity of target and effect,
amplify hormone response
what hormones use membrane receptors
peptides and catecholamines
what is activated by a membrane receptor
second-messenger systems to activate or inhibit existing proteins
what hormones use nuclear receptors
steroids and thyroid
what are nuclear receptors
transcription factors
where are nuclear receptors bound
hormone response elements in promoter of target cells
3 things that modulate hormone effects (effects are proportional to:)
number of receptors,
post binding regulation (transcriptional / post-transcriptional regulation),
hormone concentration
3 types of control secretion rates can be under
negative feedback control,
response to stimulus,
biological rhythms
what is permissiveness and give an example
presence of one hormone increases activity of another
thyroid hormone increases epinephrine receptors
what is antagonism and give an example
one hormone opposes the actions of another
insulin and glucagon have opposing effects on glucose
what is the ‘command centre’ in vertebrates
hypothalamus-pituitary complex
what is the posterior pituitary made of
nervous tissue
what is synergism and give an example
complementary actions so that their combined activities are greater than separate activities
glucagon and epinephrine increase glucose levels
what is the anterior pituitary made of
glandular tissue
name 2 hormones secreted by the posterior pituitary and 2 areas they can act
vasopressin - acts on nephrons in the kidneys increasing permeability, also act on arterioles causing vasoconstriction
oxytocin - acts on uterus stimulating contractions, also acts on mammary glands stimulating milk ejection
5 hormones released by anterior pituitary and what they do
thyrotropes - act on thyroid gland,
somatotropes - inhibit / release of growth hormone,
gonadotropes - LH and FSH release
lactotropes - prolactin releasing hormone for breast milk,
corticotropes - act on adrenal glands to release cortisol
what happens if growth hormone is stimulated
bone and soft tissue growth, increase in cell number and size
what is the role of thyroid hormones
regulate metabolism,
growth and development,
metamorphosis
