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Nerves & Hormones - PowerPoint PPT Presentation

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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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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

  • Axon

  • Axon terminal

3 main types of Neurons:

sensory neuron

motor neuron

relay neuron

Online video

Online animation

Resting Potential: Na/K Pump



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.

Synaptic Transmission


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]

Endocrine System: neuron

  • Major endocrine glands.

  • (Male on the left, female on the right.)

  • Pineal gland

  • Pituitary gland

  • Thyroid gland

  • Thymus

  • Adrenal gland

  • Pancreas

  • Ovary

  • Testes

Hormones: neuron

  • 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

Homeostasis: neuron

  • 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

Homeostasis: neuronThermoregulation

Thermoregulation is an example of homeostatic mechanism.

Homeostasis: neuronThermoregulation 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:

Homeostasis: neuronThermoregulation in endotherms



Homeostasis: neuronThermoregulation in endotherms

Homeostasis: neuronThermoregulation in endotherms

Homeostasis: neuronThermoregulation in endotherms

animation neuron

animation neuron


animation neuron