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Neurology Questions
Brain Basics - The Neuron
Question | Answer |
---|---|
What is a Neuron? | The neuron is the basic working of the brain, a specialised cell designed to transmit information to other nerve cells, muscle, or gland cells. |
How many neurons are in the body? | The mammalian brain contains between 100 million and 100 billion neurons, depending on the species. (Humans have approximately 100 billion neurons) |
What does a neuron consist of? | Cell body, Dendrites and Axon |
What is in the cell body? | Nucleus and Cytoplasm |
What do dendrites do? | Dendrites extend from the cell body and receive messages from other neurons |
What is a myelin sheath and what is it made of? | The myelin sheath is a covering of most axons. It accelerates the transmission of electrical signals along the axon. It is made up of special cells called glia. Glia in the sheath are called oligodendrocytes in the brain and Schwann cells in the PNS |
What do axons do? | When neurons receive or send messages, they transmit electrical impulses along their axons which can range in length from a tiny fraction of a centimetre to about a metre or more. |
What are synapses? | Synapses are the contact points where one neuron communicates with another. |
What are glia cells? | The brain contains at least ten times more glia than neurons. They have many jobs including transporting nutrients to neurons, cleaning up brain debris, digesting parts of dead neurons, helping to hold neurons in place. |
What is an action potential? (Simply) | When a nerve impulse begins, a reversal in the electrical potential occurs on the cell's membrane as the neuron switches from an internal negative charge to a positive charge state. This change then passes along the axon. |
How do nerve impulses work? | Nerve impulses involve the opening and closing of ion channels. These are selectively permeable, water filled molecular tunnels that pass through the cell membrane and allow ions to enter or leave the cell. |
How do neurotransmitters work | After and action potential, a neurotransmitter is diffuses across the synapse to the receiving cell and bind to (often a neuron but could be a muscle or gland cell). These receptors act as on or off switch for the next cell and triggers a response. |