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What is an Endocrine System?
A set of hormone secreting glands within the body of an animal
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What is the function of the Endocrine System?
Homeostasis, communication and response to stimuli
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What is a hormone?
A hormone is a chemical messenger (protein) secreted by an endocrine gland into the bloodstream and carried to a target organ where it causes a response
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What is an endocrine gland?
An endocrine gland is a ductless gland, produces & secretes hormones directly into the bloodstream, eg thryoid - thyroxine
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What is an exocrine gland?
An exocrine gland has ducts, secretes directly to site of action eg salivary glands- saliva- salivary ducts-mouth
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Differences between Nervous System and Endocrine System?
- 1. Nervous is faster
- 2. Nervous shorter in duration
- 3. Nervous stops quicker
- 4.Nervous response is much more local
- 5.Nerve 'messages' are conducted electrically, endocrine chemically
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Pituitary (master) gland?
- 1. Growth hormone - stimulates growth
- 2. Prolactin- stimulates milk formation in mammary glands
- 3. Pituitary- muscle contractions at birth, milk ejection
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Pineal gland?
Melatonin - natural sleep, enhances immunity
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Hypothalmus?
GHRF- stimulates pituitary to produce growth hormone
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Thryoid?
Thryoxine- controls metabolism
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Adrenals?
Adrenaline- emergency response
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Islets of Langerhans (pancreas)?
Insulin- stimulates the uptake of glucose from blood, maintains blood sugar level
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Ovary?
- Oestrogen- female 2ndary characteristics, graafian follicle formation, control menstrual cycle.
- Progesterone- maturation of uterine lining, prep for pregnancy
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Testes?
Testosterone- male 2ndary characteristics, sperm
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Thryoid Gland in detail?
- 1. Thryoxine
- 2. Regulation of metabolic rate, growth and development
- 3. Iodine is needed for thryoxine formation
- 4. Iodine is absorbed from blood by active transport
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Thryoxine Deficiency? HYPOthryoidism
- Underactivity of thyroid gland. Insufficient thyroxine. Cretinism in kids-poor, stunted growth/dwarfism & poor brain development.
- Myxoedema in adults- fatique, low energy, reduced resistence to disease, sluggishness, reduced metabolic rate-weight gain. Lack of iodine can cause this
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Thryoxine EXCESS? HYPERthyroidism
- Overactivity of thyroid gland. Overproduction of thyroxine. Raised metabolism, greater appetite, weight loss, restlessness, protruding eye- Graves Disease
- Drugs suppress thyroid gland, or surgically remove part of the gland, radioactive iodine to destroy part of gland
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Regulation of Thyroid action?
- TSH ( thyroid stimulating hormone)
- Released in blood, causes gland to produce thyroxine.
- If thyroxine level is correct- tsh not produced-no more thyroxine produced. Correct level of thyroxine has a NEGATIVE effect- Negative feedback
- Below normal thyroxine level-tsh made- more thyroxine produced-thryoxine level correct it switches off
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Hormone supplements?
- Insulin for diabetes-under-secretion of insulin- allows glucose to enter cells from the blood
- Growth hormone for potential cretinism?
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