Endocrine: Scope of Hormones Flashcards
Name the two body systems of control and communication which overlap and integrate at many levels
- The nervous system
- The endocrine system
Define Hormone:
A chemical mediator that is secreted by an endocrine tissue or gland into the blood, which transports it to its target cells
Define Endocrinology
The study of the homeostatic chemical adjustments and other activities that hormones accomplish
Name the four types of intracellular communication mediated via extracellular chemical messengers:
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- Paracrine secretion
- Hormone secretion
- Neurotransmitter secretion
- Neurohormone secretion
What type of secretion is this?
What type of secretion is this?
What type of secretion is this?
What type of secretion is this?
Name some regulatory effects hormones exert throughout the body:
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- 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
- controlling sexual differentiation and reproduction
- regulating red blood cell production
- controlling and integrating activities of both the circulatory and digestive systems
What class of hormones are hydrophilic:
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Lipophilic:
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Hydrophilic:
- Peptide
- Catchecolamines
- Indoleamines
Lipophilic:
- Thyroid hormones
- Steroid hormones
What does solubility properties of a hormone determine:
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- How the hormone is processed by the endocrine cell
- How the hormone is transported in the blood
- How the hormone exerts its effects at the target cells
Location of hydrophilic peptides and catecholamines:
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Lipophilic steroids and thyroid hormone:
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Hydrophilic peptides and catecholamines:
- poorly soluble in lipid
- bind to specific receptors on the outer PM surface of the target cell
Lipophilic steroids and thyroid hormone:
- bind with specific receptors located inside the target cell
General means of hormone action
How do surface binding hydrophilic hormones function?
How do lipophilic hormones function?
Surface binding hydrophilic hormones function largely by activating 2nd messenger pathways within a target cell
Lipophilic hormones function mainly by activating specific genes in the target cell to cause formation of new intracellular proteins
The effective plasma concentration of free, biologically active hormones can depend upon:
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- Hormones rate of secretion into the blood by the endocrine gland
- For some hormones, its rate of metabolic activation or conversion
- For lipophilic hormones, its extent of binding to plasma proteins
- Its rate of removal from the blood by metabolic inactivation and excretion in the urine
General mechanisms controlling secretion include:
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- Negative feedback control
- Neuroendocrine reflexes
- Diurnal rhythms
Endocrine disorders
Most commonly result from: ____________________________
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Occassionally, endocrine dysfunction arises because:
Most commonly result from abnormal plasma concentrations of a hormone caused by inappropriate rates of secretion:
- Too little hormone secreted - hyposecretion
- Too much hormone secreted - hypersecretion
Occasionally endocrine dysfunction arises because target cell responsiveness to the hormone is abnormally low (even though plasma concentration of the hormone is normal)
Hyposecretion
Primary:
Factors that can cause primary hyposecretion:
Secondary:
Treatment:
Primary: abnormality within the gland
Factors causing this include genetic, dietary, chemical or toxic immunological, disease, iatrogenic, idiopathic
Secondary: endocrine gland is normal but is secreting too little hormone because of a deficiency of its tropic hormone
Treatment: typically hormone replacement therapy
Hypersecretion
Primary:
Secondary:
Causes:
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Treatment:
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Primary: defect lies in gland itself
Secondary: excessive stimulation from outside
Causes:
- Tumours - continuously secrete excess hormone
- Immunological factors - abnormal antibody mimics TSH
Treatment
- Removal of tumour
- Drugs - block hormone synthesis or inhibit secretion/action of hormone
