Nervous System: Components, Nerves, Neurons and Neural Transmissions YouTube Lecture Handouts for NET, IAS, State-SET (KSET, WBSET, MPSET, etc.), GATE, CUET, Olympiads etc.
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Nervous System: 2 Components and Neurons
Components of Nervous System
Peripheral Nervous System
- Somatic: Message to & from sense organs & skeletal muscles – Striated Muscles
- Autonomic (self-governing) : Message to & from internal organs & glands – Smooth Muscles
Neurons
- Sensory Neurons – input from sense organs
- Motor Neurons – Stimulate muscles & movements
- Interneurons – b/w sensory & motor & interconnections
- Glial Cells – Care & feeding of neurons & connection among neurons, these are 10 times that of neurons
Structure of Neuron
Neuron
How Information Moves?
- Nerve Impulse - Primarily Electrical
- Communication b/w neurons – Chemical – Neurotransmitters
- Neurotransmitters – Either excite or inhibit
Nerve Impulse
- Electrically charges molecules – Ions inside neurons
Will be discussed in separate tutorial
Neurotransmitters
Neurotransmitter | Mode of Action | Deficiency | Excess |
---|---|---|---|
Acetylcholine (blocked by drug curare) | Excitatory | Alzheimer՚s | Violent muscle contractions |
Dopamine (drug cocaine behaves similarly) | Excitatory | Parkinson՚s | Schizophrenia |
Glutamate | Excitatory | Tiredness | Neuron Death & Autism |
Norepinephrine | Excitatory | Depression | Anxiety |
Serotonin | Inhibitory | Anxiety, Mood Disorder, Insomnia | Autism |
GABA | Inhibitory | Anxiety | Sleeping & Eating Disorders |
Endorphin | Inhibitory | Experience Pain | No information on Pain |
Neuropeptides
- Don՚t carry message directly
- Brain chemicals that regulate activity of other neurons
- Enkephalins – Opiate like regulators to relieve pain & stress
- Endorphins – by Pituitary Glands to relive pain & stress
Neural Networks
- Interlinked collection of neurons
- A reflex arc – stimulus provokes automatic response
- One neuron may weigh hundred of inputs to outward message
- Each neuron is a tiny computer – billions of neurons & trillions of synapse
Reflex Arc
Neuroplasticity & Neurogenesis
Neuroplasticity – Capacity of brain to change in response to experience
- Hebb՚s rule: Repeated activation of synapse b/w 2 neuron strengthen connection between them
- If in complex situation – longer dendrites & more synapse (eg. rat)
- Human brain is neuron-plastic – patience & persistence
Neurogenesis – Growth of new neurons & production of new brain cells
- Constraint Induced Movement Therapy – Constraint right arm so that impaired left arm becomes active
✍ Manishika