How is your nervous system like a computer?

How is your nervous system like a computer?

There are four primary functions of the nervous system Sensing the world – Vision, Hearing, Smell, Taste, Touch Transmitting information Processing information Producing a response

The evolution of the nervous system reflects increasing complexity and centralized control All animals except sponges have nervous system tissue The most basic nervous system is the nerve net (e.g. Hydra) Increasing centralized control (ganglia) is evident in worms and insects (e.g. leech) Fish, birds and mammals have evolved a central control center, the brain

The human nervous system can be divided into two components The central nervous system – Brain and Spinal cord The peripheral nervous system – – Any nervous tissue not contained within bone Composed of the sympathetic and parasympathetic divisions

The nervous system is composed of two basic types of cells Neurons – The communication mechanisms Three types: Sensory, Inter-neuron, Motor Glial cells – The support mechanisms Provide myelin (oligodendrocytes, Schwann cells) Bring nutrients (astrocytes) Remove damaged cells (microglia)

Each part of a neuron has a particular function Dendrites - input Cell body (Soma)- integration Axon - output

Neurons are always ready to send information An inactive neuron is at its resting potential – The resting potential is due to more negatively charged ions inside the cell (intracellular Cl-, Anions(-), K ) compared to outside the cell (extracellular Na )

When a neuron is stimulated, it may send an action potential (nerve impulse) to the next cell in a circuit During the action potential, the charge across the cell membrane reverses, making the inside of the neuron positive due to the positive ions (Na ) moving from the extracellular space to the inside of the cell The cell returns to the resting potential when K ions move to the extracellular space Animation

The action potential moves down the length of the axon in one direction The action potential moves in one direction because the membrane is refractory (unable to respond) once the action potential has been initiated at any particular place on the membrane

The action potential initiates a chemical process at the synapse Neurotransmitters are released into the synapse between neurons when an action potential reaches the end of the axon There are many different neurotransmitters in the nervous system Animation – Each neuron produces only one type of neurotransmitter

The reflex arc illustrates information flow in the nervous system Reflexes are automatic. You do not have control over whether they happen, but you may be able to control how strong they are.

Functional Neuroanatomy What does “localization of function” mean in the nervous system?

Functions are well organized in the central nervous system Organization of the nervous system begins in the spinal cord Peripheral N.S. Dermatome Reflexes Pattern generation

The reflex arc illustrates information flow in the nervous system Reflexes are automatic. You do not have control over whether they happen, but you may be able to control how strong they are.

The anatomy and function of the brain can be best understood in 3 dimensions This is the middle of your brain This is the side of your brain

The brainstem controls basic life functions Coma Cranial nerves Pupil function Fight or Flight Heart-rate, breathing and control of other internal organs is controlled here. Damage here will usually kill you. Medulla

The Limbic System controls your emotions and memories Damage to these areas of the brain can lead to amnesia or emotional disturbanc es Declarative amnesias Partial seizures Attention deficits Fear/Aggression

The basal ganglia and cerebellum control movement and output from the brain The basal ganglia put movements in order and the cerebellum makes them happen at the right time Sequence and Timing Eye movements Motor tasks Procedural amnesia balance and coordination Parkinson’s Disease Huntington’s Chorea Ataxia

The cortex is where anything you experience and/or learn is stored There are four main lobes of the cortex, each with different functions Parietal Sense of Space Frontal Touch Movement Planning and decisions Temporal Declarative Memory Hearing Emotion Occipital Vision

The sensory and motor homunculi are a perfect example of functional organization in the nervous system ‘Little man’ Homonculus