Nervous system Flashcards
Whats the nervous system?
Our nervous system is a complex network of nerve cells that carry messages to and from the brain and spinal cord to different parts of the body.
It helps to coordinate different organs and cells in the body.
It is subdivided into the Central Nervous System (CNS) and Peripheral Nervous System (PNS).
What is the central nervous system made up of?
Made up of the brain and spinal cord.
whats the peripheral nervous system do (PNS)?
It transmits messages via neurons (nerve cells) to and from the CNS.
It is then further divided into:
Somatic nervous system
Autonomic nervous system
What do Sensory neurons do?
Carry impulses from the sensory receptors to the spinal cord and brain.
The sensory neurons convert information from the sensory receptors into ‘neural impulses’ which, once they reach the brain, are translated into sensations to enable an appropriate response.
EXT- not all impulses go all the way to the brain. Some neurons stop at the spinal cord which allows for reflex responses.
Motor Neurons:
These are located in the CNS and project their Axons (‘branches’) out to the muscles to control their actions.
They form Synapses with muscles and cause them to contract or relax allowing movement.
When the motor neuron is stimulated, it releases Neurotransmitters into the Synapse that bind to the receptor sites on the muscle and trigger a response.
The rate at which the Axon in the motor neuron fires will determine the level of movement.
The muscles relax when the motor neuron is inhibited.
Nerve Action:
Nerve cells or ‘Neurons’ transmit impulses (messages) around the body. The most common of these are the motor and sensory neurons.
A stimulus causes an exchange of chemicals between the outside and inside of the neuron to pass across the cell membrane.
This swapping of chemicals sets off a further exchange in the cytoplasm starting off a chain reaction.
Whats a synapse?
Where two neurones meet, there is a tiny gap called a synapse. Signals cross this gap using chemicals called neurotransmitters
The Nervous System consists of two intergrated systems known as…
Our nerve system consists of two integrated systems/networks – the voluntary and the involuntary systems.
The Voluntary System:
Consists of peripheral nerves spreading out from the brain and spinal cord – these together are known as The Central Nervous System.
These nerves contain two types of nerve cell:
1. Sensory neurons – carry messages from sense organs to the CNS
2. Motor neurons – carry messages from the CNS to tissues
The Brain collects information from the sensory receptors and relays this to the muscles and glands of the body through the spinal cord.
The Involuntary or autonomic system is…
Made up of two further networks of nerves – the sympathetic and the parasympathetic systems.
Normally we are not aware of using these nerves but they play a vital role.
The sympathetic system prepares us for action by activating functions needed for survival and supressing less important activities.
The parasympathetic system is an antagonist – it does the opposite – damping down the sympathetic and restoring the body to its normal ‘resting’ state.
Whats the synapse animation?
- An electrical impulse travels along an axon.
- This triggers the nerve-ending of a neuron to release chemical messengers called neurotransmitters.
- These chemicals diffuse across the synapse (the gap) and bind with receptor molecules on the membrane of the next neuron.
- The receptor molecules on the second neuron bind only to the specific chemicals released from the first neuron. This stimulates the second neuron to transmit the electrical impulse.
Whats the autonomic nervous system do?
Autonomic nervous system: governs vital functions in the body such as breathing, heart rate, digestion, sexual arousal and stress.
whats the somatic nervous system do?
Somatic nervous system: governs muscle movement and receives information from sensory receptors.
What is the brain?
The brain is the centre of all conscious awareness. The brains outer layer (cerebral cortex) is on 3mm thick and covers the brain like an orange peel.
The brain is highly developed in regards to our mental functions.
The brain is divided into two hemispheres.
What is the spinal chord?
The spinal cord is an extension of the brain. It passes messages to and from the brain and connects our nerves to the PNS. Also responsible for our reflexes.
