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Nerves & Hormones

Nerves & Hormones. Nervous System:. Central Nervous System: (The center of integration and control) 1. The brain 2. The spinal cord Peripheral Nervous System: The nervous system outside of the brain and spinal cord. Basic Nerve cell Structure: Neurons. Dendrites Cell body

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Nerves & Hormones

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  1. Nerves & Hormones

  2. Nervous System: • Central Nervous System: • (The center of integration and control) • 1. The brain • 2. The spinal cord • Peripheral Nervous System: • The nervous system outside of the brain and spinal cord

  3. Basic Nerve cell Structure: Neurons • Dendrites • Cell body • Axon • Axon terminal

  4. 3 main types of Neurons: sensory neuron motor neuron relay neuron

  5. Conduction of Nerve Impulses: Online animation

  6. Nerve impulses are conducted along the neuron

  7. Online video Online animation

  8. Resting Potential: Na/K Pump + -

  9. The Action Potential Activation gates of the Na+ channels are open, but the K+ channels remain closed. Na+ ions rush into the cell, and the interior of the cell becomes more positive. Na+ close and potassium channels open. K+ ions leave the cell and the loss of positive charge causes the inside of the cell to become more negative than the outside. A stimulus opens some Na+ channels. If the Na+ influx achieves threshold potential, then additional Na+ gates open, triggering an action potential. Na+ channels are closed, but the slower K+ remain open. Within a millisecond, the resting state is restored. Both Na+ & K+ channels are closed, and the membrane’s resting potential is maintained.

  10. Nerve impulse along a non-myelinated neuron animation

  11. Synaptic Transmission animation http://www.blackwellpublishing.com/matthews/nmj.html

  12. Synaptic Transmission animation

  13. Explain how a nerve impulse passes along the membrane of a neuron • resting membrane is polarized; • interior is –70 mV/negative relative to outside; • more sodium ions outside than inside; • more potassium ions inside than outside; • disturbance of membrane opens sodium ion channels; • sodium ions rush to inside of cell; • causing depolarization; • sodium ion channels shut; • potassium ion channels open; • potassium ions rush out; • helping to restore polarized state of membrane; • sodium-potassium pumps maintain polarity; • process repeated along the length of neuron / sodium ions diffuse between region with an action potential and the region at resting potential; [8 max]

  14. Endocrine System: • Major endocrine glands. • (Male on the left, female on the right.) • Pineal gland • Pituitary gland • Thyroid gland • Thymus • Adrenal gland • Pancreas • Ovary • Testes

  15. Hormones: • Organic substances • Produced in small quantities • Produced in one part of an organism (an endocrine gland) • Transported by the blood system • To a target organ or tissue where it has a profound effect

  16. Homeostasis: • Homeostasis involves maintaining the internal environment • (tissue fluid, blood) between limits. • Examples: • Blood pH • Blood carbon dioxide levels • blood glucose concentration • body temperature • water balance

  17. Homeostasis: Thermoregulation Thermoregulation is an example of homeostatic mechanism.

  18. Homeostasis: Thermoregulation in endotherms The body must balance its heat budget • by conduction from warm air surrounding the body • by the body’s metabolic activity which generates heat e.g. when muscle move • by conduction and radiation to cold air (or water) • by evaporation of sweat from the body surface (c.f. properties of water) • Humans can also affect their body temperature by changing their behavioure.g. wearing different clothes, seeking shade Heat is gained: Heat is lost:

  19. Homeostasis: Thermoregulation in endotherms animation epidermis

  20. Homeostasis: Thermoregulation in endotherms

  21. Homeostasis: Thermoregulation in endotherms

  22. Homeostasis: Thermoregulation in endotherms

  23. animation

  24. animation animation

  25. Glucose Homeostasis:

  26. animation

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