The Nervous system By Amber Henry and Sarah-Jade Mckillop.

The Nervous system

The Eye

How does it work??. Light enters the eye through the cornea, in dim light, the pupil expands to allow more light in and in bright light, the pupil contracts to allow less light in to the eye. The light then passes through the lens, causing it to converge and cross. The lens can change shape depending on the distance of the object from the eye. When the light reaches the retina, the rods and cones convert the image into an electrical signal, The brain analyses the information and interprets the signals as light. The brain then reverses the image and, if necessary, fills in the blind spot, leaving the image of what we see through our eyes in our brain.

The Brain…

How it works?? It is a network that controls and coordinates all the activities by transmitting messages or signals from the brain to the different regions of the body and vice versa. It works with the help of nerves or neurons, which conduct the signals or impulses between the two components of the nervous system The brain in turn processes these stimuli and sends them back to the other parts of the body telling them to react to a particular type of stimulus. The motor neurons are responsible for receiving signals from the brain and spinal cord and transmitting them to the other organs of the body.

The human brain can be divided into three parts, forebrain, midbrain and hindbrain,. The forebrain consists of the cerebrum, which is the largest part of the brain and is the center of intelligence, memory, emotion, personality, speech and the ability to feel. The inner part consists of the thalamus, hypothalamus and pituitary gland. The thalamus transmits the messages from the sensory organ to the cerebrum. while the hypothalamus is responsible for regulating pulse, appetite and automatic processes

The midbrain is located underneath the middle of the forebrain and sends messages or impulses coming to and from the brain. On the other hand, the hindbrain, which is located below the back end of the cerebrum, consists of the cerebellum, pons and medulla. The cerebellum controls movement and balance, while the pons and the medulla coordinate messages and automatic functions like breathing, heart rate, digestion and blood pressure

Neurons.

Nervous system The nervous system is a network of cells called neurons which transmit information in the form of electrical signals. Your brain has about 100 billion neurons, and each communicates with thousands of others – as many connections as in the internet, the biggest connection on the planet. Neurons communicate with each other by chemicals moving across the gap between them.

Neurons-transmit info to the brain

Depression depression of the central nervous system that can result in decreased rate of breathing, decreased heart rate, and loss of consciousness possibly leading to coma or death.depressioncentral nervous system means slowing down of the nervous system. Nervous system depression causes things like slowed heartbeat, dulled mental ability, and slow reflexes. Some drugs and medical conditions can cause this. Sedatives are one medication that causes depression of the nervous system.

Pain killers When part of your body is injured, special nerve endings send pain messages back to your brain. Painkilling drugs interfere with these messages, either at the site of the injury, in the spinal cord or in the brain itself. Many painkillers are based on aspirin and opiates.

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