chemicals released into the blood stream that target tissues and organs, influencing cell growth and metabolism
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what systems control homeostasis
ANS and endocrine system
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Two types of hormones;
lipid soluble; steroid and thyroid, water soluble; amine, peptide and protein
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where are the receptors for water soluble hormones?
on cell membrane
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where are the receptors for lipid soluble hormones?
inside the cell
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what 5 things do hormones do?
alter plasma membrane by opening or closing ion channels, stimulates synthesis of enzymes, activates/deactivates enzymes, induces secretory activity, stimulates mitosis
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what is mitosis
cell division
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where is the hypothalamus situated?
below the thalamus in the brain
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What are the main functions of the hypothalamus?
secretes stimulatory and supresses inhibitory hormones that regulate all aspects of growth, development, metabolism and homeostasis
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where is the pituitary gland?
fossa of the sphenoid come below the hypothalamus (attached by a stalk)
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What are the two main parts of the pituitary gland?
anterior and posterier
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anterior pituitary gland controls?
secretion of endocrine glands
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posterior pituitary gland releases what hormones?
ADH and oxytocin
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Thyroid gland is what sort of gland and where is it situated?
In front of the trachea. endocrine gland
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how many lobes does the thyroid gland have?
2 lobes. right and left - connected with isthmus
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what is the thyroid gland made from?
small sacs called thyroid follicles
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follicular cells stimulate the release of?
T3 and T4
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What does T3 stand for?
Thyroxin (more active)
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What does T4 stand for?
Thyrotropin (more produced)
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What do T3 and T4 do?
simulate metabolic activities and increase sensitivity of CV system and NS to adrenalin and noradrenalin
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What do C cells release?
calcitonin
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what does calcitonin do?
lowers blood calcium levels by promoting calcium storage in bone cells and inhibiting reabsorption in tubules
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Another name for C cells?
parafollicular cells
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what regulates Parathyroid secretion?
calcium levels
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What type of cell produces parathyroid hormones?
chief cells
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Main functions of parathyroid hormone?
increase calcium levels, increasing absobtion in kidneys and releases calcium by releasing osteoclasts
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Where are the adrenal glands?
superior to each kidney
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Outer part of adrenal gland?
cortex
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Innter part of adrenal gland?
the medulla
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How many hormones are secreted by the adrenal cortex?
3
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Outer part secretes
mineral corticoids
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Middle part secretes
glucocorticoids
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Inner part secretes
sex hormones (androgens)
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what does aldosterone do?
maintains water and electrolyte balance. simulates reabsorption of sodium ions and secretion of potassium ions
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what does low blood volume and low sodium levels cause?
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