Endocrine system secretes chemical messengers, called hormones act on receptors to cause change at target organs
endocrine glands. ductless, synthesises and secretes hormones
Endocrine system is long lasting and slow. whilst the nervous system short term and fast
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Hormones
peptide.
Amino- acid derived
lipid derived
Steroids
Eicosanoids
Derived from cholesterol
androgens, oestrogens and progesterone, corticosteroids, calcitriol
arachidonic acid, a phospholipid found in cell membranes
prostaglandins, clotting factors, leukotrienes
Short-chain polypeptides (ADH and OXT)
Small water-soluble hormones
that can cross cell membranes
Structurally related to amino
acids (tyrosine & tryptophan)
thyroid hormone, serotonin and
melatonin
chains of amino acids, glycoproteins and short polypeptides and small proteins
cannot pass through cell membranes due to size and water solubility
most abundant type. TSH, LH, FSH and insulin
Glands
Intracellular communication
Direct communication
Autocrine communication
Chemicals involved are autocrine
prostaglandins secreted by smooth muscle cells cause the same cells to contract
Exchange of ions and molecules between adjacent cells across gap junctions
occurs across two cells of the same type
Highly specialised and rare
Endocrine communication
Paracrine communication
Chemical information transfers information from cell to cell within a single tissue.
Hormones are produced by the cell to then act locally on that cell
Endocrine release chemicals (hormones) that are transported in the blood stream
Alters metabolic activities of many organs
Synaptic communication
Across synapses and uses neurotransmitters
Effects limited to specific areas
Target cell must have appropriate receptors
Target cells must have receptors to bind and read hormonal messages
Change types, quantities or activities of enzymes and structural proteins in target cells
Can alter metabolic activities of multiple tissues and organs at the same time
Hormones
Can alter metabolic activities of multiple tissues and organs at the same time
Hypothalamus, pituitary gland, pineal gland, thyroid and parathyroid glands, adrenal gland, pancreas and reproductive glands.
Anti- diuretic hormone, Corticotropin-releasing hormone, Thyrotropin-releasing hormone (TRH), Gonadotropin-releasing hormone (GnRH), Growth hormone–releasing hormone. Prolactin-releasing hormone (PRH) ( Dopamine) Oxytocin
Hypothalamus
Reproduction and stress responses, Regulates metabolism and energy balance. coordinates function between cells, produces hormones, controls release. Maintains homeostasis. Regulates water and electrolyte levels. Biological clock and aids immune system
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Function
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