IB Biology C2.2 Notes

In Topic C2.2, the focus is on the nervous system. Although there are many cells that compose the nervous system, you only need to focus on one type: neurons. These are primarily responsible for transmitting electrical impulses and divided into two types:

1. Sensory neurons - these transmit signals from receptors to the brain.
2. Motor neurons - these transmit signals from the brain to effectors (muscles).

You are expected to know the structure of a neuron well. It is composed of:

1. Dendrites - short branched fibers that connect to other neurons and receive their impulses.
2. Cell body (soma) - contains a cytoplasm and nucleus and receive all impulses from the dendrites.
3. Axon - a long cylindrical 1 μm fiber that transmits the impulses away from the soma to other structures.