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8 Cards in this Set
- Front
- Back
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Importance homeostasis during exercise > thermoregulation |
• cell functioning > temp too high (due to exercise) = enzymes denature > metabolic reactions less efficient |
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Homeostasis |
Maintenance of constant internal environment due to control systems (state dynamic equilibrium) |
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Positive feedback |
Output resulting in control mechanism enhancing/ amplifying the change |
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Negative feedback |
• bringing lvl back to normal when raised/lowered by external influences • output results in a control mechanism reversing/inhibiting the change (effectors) • works within narrow limits (if change too great unable to counteract this) |
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Mechanisms to reduce body temperature |
1) sweat glands secrete sweat > water in sweat evaporates cooling the surface (> heat loss) 2) erector pili muscles relax > hairs lie flat > less air trapped so less insulated > ^ heat can be lost 3) vasodilation of arterioles > muscles in arteriolar walls relax > blood flows closer to skin’s surface so able to radiate heat out through skin |
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How does a hormone try to affect a cell |
1) enters cell 2) binds to receptors on cell membrane > change |
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Peptide hormone |
1) hydrophobic & lipophobic > x freely diffuse through the membrane > binds to receptors on membrane 2) hormone-receptor complex forms > activates second messengers (in cytoplasm) 3) second messenger molecules activate enzymes called protein kinases 4) enzymes trigger a cascade of reactions in the cell 5) during cascade transcription factors are activated > affect transcription of genes in nucleus of the cell |
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Steroid hormone |
1) lipids that are lipophilic > able to diffuse across cell membrane 2) will bind to receptors molecules in the cytoplasm/ directly to DNA in the nucleus 3) form an active hormone-receptor complex 4) activated complex moves into nucleus > binds to DNA > acts as/ activates transcription factors for gene expression |
