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The endocrine system - Coggle Diagram
Regulates growth, development, reproduction and homeostasis
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Hormones: chemicals that are produced by cells in one part of the body, carried by blood and bring about an effect in another part of the body. Target cell have complementary receptors that bind with hormones and initiate a response inside the cell. Binding causes changes to metabolism in target cells. Hormone-receptor binding initiates transcription hence production of a protein that then alters the cell metabolism
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Homeostasis
- Is the maintenance of a constant internal environment
- Involves processes that return the internal environment to within a narrow range referred to as the tolerance limit.
- Processes involved in maintaining homeostasis involves the nervous system, the endocrine system and behavioural responses
- Factors for which organisms have tolerance limits include body temperature, water availability, blood glucose levels and carbon dioxide concentration.
- Homeostasis involves both stimulus-response and negative feedback models
Stimulus-response model
A change in the internal condition acts as a stimulus that is deteced by sensory receptors. Sensory receptors respond to a stimulus by sending nerve impulses to a control centre such as the brain that interprets sensory input and coordinates the appropriate response. The control centre then sends nerve impulses or hormones to effectors such as muscles and glands that facilitate a response
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Sensory receptors
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Types of receptors
Mechanoreceptors: sense physical deformation causes by stimulus such as pressure, touch, stretch, motion and sound
Electromagnetic receptors: detect electromagnetic energy such as light, electricity and magnetism
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Chemoreceptors: response to changes in the concentration of chemical causesd by stimuli such as smell and taste as well as responding to changes in pH caused by carbon dioxide and osmolarity caused by the gain and loss of water
Nociceptors: detect painful stimuli that could damage animals tissues and triggering defensive reactions
Negative Feedback Model: Control mechanism that helps return a variable to the tolerance range by reducing the original stimulus