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Endocrine system
hormones general
| Question | Answer | |
|---|---|---|
| how is the endocrine system involved in homeostasis | Chemical messengers - hormones Made of various endocrine glands (made up of secretory cells) | |
| endocrine vs exocrine | Endocrine - ductless - secretes hormones into intercellular (outside cell) fluid (exocytosis) surrounding the cells and then into the blood | Exocrine - duct secretes a substance into a duct and this is carried to surface (salivary & sweat) |
| hormones | Secreted from endocrine glands Chemical messengers Transported via blood | Move in & out of blood via diffusion All body cells come in contact only target cells affected |
| What are target cells | Have a receptor protein that corresponds with hormone Hormones are very specific in action Lock and key (we know this) | Hormones can act on Individual cells Groups of cells Tissues Organs |
| types of hormones | Proteins - LH, FSH, insulin Amines - adrenaline, thyroxine Steroids - estrogen, cortisol | Difference Structurally different All ind to protein receptor Way they cause change is different |
| Steroids | Lipid based Travels in blood attached to plasma protein Attach to protein receptor inside the cell - on mitochondria or in nuclues | In nucleus - activates a gene Changes the proteins being made |
| Proteins & Amines | Protein & Amino acid based Travel dissolved in blood plasma Attach to protein receptor found in cell membrane | Activates particular enzymes Signals a secondary messenger - cascade of reactions inside the cell follow |
| Effect | Change the type, activities or quantities of proteins produced (always) Often act on enzymes therefore act on cell | -Activate certain genes → start production of particular enzyme or structural protein -Change shape/structure of enzyme → turn on/off -Change rate of transcription/translation → change rate of production of enzyme or structural protein |
| Enzyme amplification | Small stimulus - very large effect 1 hormones triggers cascade of reactions 1 hormones molecule -> 1000s of enzymes | +++ |
| Hormone clearance | Once a hormone has done its job, is no longer needed Breakdown the hormone molecules | -Inside the target cell with the help of particular enzymes -Transported to liver or kidneys to be broken down and excreted in bile or urine |
| Feedback control - why must control hormone levels | -Hormones are very powerful -over/under secretion can have a huge impact on the bodys normal functioning -Control with (usually negative) feedback loops | Hyperthyroidism - thyroid gland poduces too much thyroxine Hypothyroidism - not producing enough, swells forming a goitre |
Created by:
wegonebefine
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