endocrine

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What is a hormone?
a chemical mediator that is secreted by an endocrine gland/ tissue into the blood which transports it to its target cells
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what are the types of intercellular communication mediated via extracellular chemical messengers
paracrine, neurotransmitter hormonal and neurohormone secretion
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what are some of the regulatory effects exerted by hormones, throughout the body
Regulating metabolism, water and electrolyte balance Regulation of nutrient supply Inducing adaptive changes to help the body cope with stressful situations Promoting smooth, sequential growth and development
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part 2 for the effects
Controlling sexual differentiation and reproduction Regulating red blood cell production Controlling and integrating activities of both the ciruculatory and digestive systems
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describe the complexity of endocrine function
single endocrine- produce multiple hormones. single hormone- secreted by more than 1 endocrine gland. single hormone- more than 1 type of target cell
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part 2 for complexity
and therefore can induce more than a single target cell can be influenced by more than one type of effect. A single target cell can be influenced by more than one type of hormone. the same chemical messenger can be a hormone or neurotransmitter
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what is a tropic hormone
a hormone that has its primary function the regulation fo hormone secretion by another endocrine gland (TSH)
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What is a non tropic hormone ?
a hormone that does not act on endocrine cells but on target cells
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what is a trophic hormone?
hormones that stimulate and maintain their endocrine target tissues
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what hormones are hydrophilic ?
peptides, catecholamines and indoleamines
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give some examples of catecholamines
tyrosine, adrenaline, adrenal medulla
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give some examples of indoleamines?
tryptophan, melatonin, pineal gland
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what are the lipophilic hormones?
thyroid hormone and steroid hormones
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what are some examples of thyroid hormone
amine, iodinated tyrosine derivative
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what does the solubility properties of a hormone determine?
how the hormone is processed, transported and how it is exerted on the target cell.
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how are hydrophilic peptides hormones processed. first 3 steps
1.preprohormones are synthesised by ribosomes on rough ER.2. they migrate to the Golgi complex in transport vesicles that pinch off from the smooth ER.3. Enzymes in the ER transform the preprohormones to active hormones. 4 the Golgi couples packages
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the other 2 parts
4 the Golgi couples packages the finished hormones into secretory vesicles and are stored in the cytoplasm until signal for secretion. 5. on stimulation the secretory vesicles fuse with the PM and release their contents by exocytosis
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how are lipophilic steroid hormones processed?
cholesterol which is a precursor for all steroid hormones is turned into steroid hormone. the lipid soluble hormones diffuse across the the pm and into the blood. rate of steroid hormone secretion depends on rate of the de novo hormone synthesis.
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how are peptide hormones transported by the blood
simply dissolved in the blood
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how are lipophilic steroid hormones and thyroid hormone transported
reversibly bind to plasma proteins
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where is the location of hydrophilic peptides and catecholamines
thye bind to specific receptors on the outer PM surface of the target cell
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where is the location of lipophilic steroids and thyroid hormones
they bind with specific receptors located inside the target cell
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how do hormones influence their target cells?
by altering the cells proteins in one of two major ways:
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how do hydrophilic hormones influence their target cells
they activate 2nd messenger pathways within the target cell. this activation directly alters the activity of pre existing intracellular proteins
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how do lipophilic hormones influence their target cells
they activate specific genes in the target cell to cause formation of new intracellular proteins (enzymatic or structural)
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on what factors does plasma conc of a hormone depend on?
the hormone's rate of secretion into the blood by the endocrine gland. rate of metabolic activation/ conversion. for lipophilic hormones its extent of binding to plasma proteins. the rate of removal from the blood by metalobilic inactivation urine e
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how is the effective plasma conc of a hormone regulated ?
-ve feedback, neuroendocrine reflexes and diurnal
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what causes endocrine disorders?
abnormal plasma conc of a hormone caused by inappropriate rates of secretion. also when target cell responsiveness to the hormone is abnormally low even tho plasma conc of a hormone is normal
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what can cause the primary hypo secretion?
genetic, dietary, chemical, toxic, immunologic, disease, iatrogenic and idiopathic
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what is secondary hypo secretion
when the endocrine gland is normal but secretion too little hormone because of a deficiency of its tropic hormone
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what causes excessive stimulation in secondary hyper secretion
tumours, immunologic factors,
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what are the endocrine glands that have a soley endocrine function
pituitary, parathyroid, thyroid and adrenal gland
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Card 2

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what are the types of intercellular communication mediated via extracellular chemical messengers

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paracrine, neurotransmitter hormonal and neurohormone secretion

Card 3

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what are some of the regulatory effects exerted by hormones, throughout the body

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Card 4

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part 2 for the effects

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Card 5

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describe the complexity of endocrine function

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