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Unit 3: Homeostasis - Coggle Diagram
Unit 3: Homeostasis
Lesson 2: Transmission
Resting Potential
At rest, the sodium gates are closed
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This causes outside of membrane to have an abundance of positive charges compared to inside. The inside of the membrane is negative compared to the outside. This is helped by negatively charged proteins.
The sodium-potassium pump pulls K+ions in for 3 Na+ ions sent out. This further creates a charge difference.
Action Potential
The mechanism by which neurons send impulses. They are comprised of electrical signals generated at the soma and moving along the axon toward the end opposite the soma.
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Depolarization
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The inside of the axon becomes temporarily positive while the outside becomes temporarily negative. The reversal of charge is known as depolarization.
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Repolarization
This is the restoring of the positive charge on the outside of the axon and the negative charge on the inside.
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Lesson 1: Neurons
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Types of Neurons
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Motor Neurons: Neurons located near effectors such as muscles and glands. They carry impulses to effectors to initiate a response.
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Lesson 6: Homeostasis
Endocrine System
The endocrine system is comprised of ductless glands that release hormones
into the bloodstream and transported to the target organ, tissues or cells.
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Hormones which are chemicals released in one part of the body and travels through the blood stream to affect the activity of cells in other parts of the body.
The release of hormones into the blood stream is a much slower but widespread form of communication.
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Target Cells
Steroid hormones are produced from cholesterol, they are lipid soluble and can diffuse across lipid bilayer of their target cell. Once inside they bind to the steroid receptor protein located in the cytoplasm or nucleus.
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Water soluble hormones cannot pass through cell membranes of their target cells and will bind to a receptor protein on the surface of the cell. They enter through the cell through receptor mediated endocytosis. This activates a second messenger in the cell and triggers a response to the hormone.
Water soluble hormones are composed of amino acids or peptides.
Maintaining Homeostasis
Maintaining homeostasis requires the close cooperation between the hypothalamus and the pituitary gland.
The hypothalamus secretes releasing hormones directly into the blood which travels to the pituitary where they control the production and release of other hormones.
Tropic hormones stimulate endocrine glands such as pituitary gland to release hormones that then act on other glands. The endocrine system is regulated by negative and positive feedback systems
The nervous system and the endocrine system often overlap as they work closely to maintain homeostasis.
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