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Hormones and Endocrinology (Hormone Signalling (Gland secrete hormones…
Hormones and Endocrinology 
Hormone is a chemical signal secreted into body fluid (often blood), and communicates regulatory messages within the body.
Functions of Hormone
- A method of communication between one body part to another
- Coordinate the organs through action and feedback
- Regulates (metabolism, growth, development, maturation & reproduction)
Hormone Signalling
- Gland secrete hormones into extracellular fluids
- Hormone reach target tissue and bind to specific receptor
- Gland secrete hormones into extracellular fluids
- Target tissue respond and resulted in feedback mechanism
- Hormone produced by endocrine gland
- Feedback reach gland to either stop or increase production of hormone
Class of Hormone
Lipid-based hormones
- lipid-soluble
- diffuse across membrane & enter cells
- bind to receptor proteins in cytoplasm & then this hormone-receptor complex moves into nucleus
- bind to receptor proteins in nucleus & then bind to DNA as transcription factors
- activate genes that result in synthesis of new proteins
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steroids
•modified cholesterol: sex hormones, aldosterone
Protein-based hormones
- hydrophilic & not lipid soluble
- trigger secondary (2°) messenger pathway
- activate cellular response
glycoproteins
•large proteins + carbohydrate: FSH, LH
amines
•modified amino acids: epinephrine, melatonin
polypeptides
•small proteins: insulin, ADH
Endocrine system
•A system of ductless glands
•Each gland contain specialized cells that synthesizes hormone
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Control & Feedback
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Heural stimulation
•Nerve impulses stimulate hormone release
•Most are under control of the sympathetic nervous system
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Hormone disorder
•Unusual level of hormones in bloodstream can leads to hormone disorder.
•It can be caused by endocrine disease or drugs interaction and if left untreated, can result in serious medical condition.
•Symptoms includes behavioral, physical or physiological changes.
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hormonal imbalance - Hyperthyrodism
- Hyperthyroidism is a common glandular disorder in cats.
- Frequently caused by excessive concentration thyroxine-a thyroid hormone in the bloodstream.
- Prolonged exposure of cortisol leads to hypercortisolism.
Some symptoms of hormonal imbalance - Hyperthyrodism
•Weight loss despite increase in appetite
•Increased activity level / Rapid heart rate
•Increased urination / Diarrhea
•Aggression / Nervousness
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