Cells and Control: The Nervous System

The human nervous system is divided into two parts: the central nervous system (CNS) and the peripheral nervous system (PNS).
The central nervous system consists of the brain and spinal cord. It controls and coordinates most of your body’s functions.
The peripheral nervous system carries messages to and from the CNS and the rest of the body.
Neurons, or nerve cells, form the basis of these systems. They are specialised for rapid signalling.
Neurons consist of a cell body, dendrites that bring information towards the cell body, and an axon that takes information away from it.
Synapses are where neurons connect with one another. Signals are transferred between neurons at synapses via chemicals called neurotransmitters.
Reflex actions are automatic responses to certain stimuli, bypassing the brain to provide quick reactions.
Sensory neurons carry signals from sensory receptors to the CNS. Motor neurons carry signals from the CNS to effectors (muscles or glands).
The speed of nerve impulses can be affected by different factors, such as temperature and pressure.
The nervous system is divided further into the somatic and autonomic systems. The somatic system controls voluntary actions, while the autonomic controls involuntary actions like heart rate.
In terms of control, the endocrine system also plays a role by releasing hormones which are slower but have more long-lasting effects than nerve impulses.
Cells in the human body that grow and divide in a controlled way can become cancerous if mutations occur in their DNA, leading to uncontrolled growth and division.
Stem cells have the potential to develop into many different cell types in the body and are used to replace damaged or diseased cells.
Embryonic stem cells can turn into any cell type. Adult stem cells have a limited range of cells they can turn into, depending on where in the body they are found.
There are ethical considerations and potential risks to take into account with the use of stem cells in medical research and treatments.