psychology nervous system

Nervous system

CNS (central nervous system): part of the nervous system made up of the brain and spinal cord. Carries sensory information up the spinal cord to the brain via sensory neurons. Carries motor messages to the PNS (peripheral nervous system) via motor neurons.

PNS (peripheral nervous system): made up of all the nerves outside of the brain and spinal cord. This carries information to the CNS from the body. PNS carries motor messages from the brain to the organs and muscles

Key functions of the CNS

• Input—to receive information

• Processing—to interpret information based off of past experiences

• Output—guide actions

Key functions of the PNS

• made up of our muscles, organs and glands

• consists of all the neurons outside of the CNS

• relay information to the CNS

• carries motor information from the CNS to the muscles and organs via the spinal cord

Somatic and Autonomic NS (nervous system):

• somatic nervous system: nerves that control voluntary movement through its control of skeletal muscles. This nervous system receives motor messages from the CNS and transports them to the skeletal muscles in the specific regions of the body. e.g., walking/running

• Autonomic nervous system (ANS): contains nerves that are connected to the CNS and the involuntary muscles that control the activity level of our internal organs and glands. By relaying messages between the CNS and the internal systems, the ANS controls the body’s internal activities that are essential to survival such as heart rate, digestion, kidney function and more. e.g., breathing as it is an autonomic subconscious thing which we don’t control

Functions of the divisions of the somatic NS:

• sensory functions—transmits sensory information from the body to the CNS via the spinal cord

• Motor functions—sends motor commands from the CNS to skeletal muscles, glands or organs for voluntary movement

Functions of the divisions of the ANS

• sympathetic nervous system—regulates the glands and internal organ function and physically prepares the body during heightened arousal, e.g., the flight or fight response

• Parasympathetic nervous system—calms the body after being under control of the sympathetic nervous system, and controls the rest and digest responses, and it also returns the body into normal function which is homeostasis

Features of Neurons

• neurons are specialised cells located in the CNS and PNS

• they are cells that receive, transmit and process information

• There are billions of these cells, each with synaptic connections to more neurons. These connections allow for messages to be passed along throughout the body

(myelin sheath is above, others not needed) only need 1,2,3,5,7,8 (2 is soma which is cell body)

Features of a neuron:

• cell body (soma): this contains a nucleus that controls the activities of the neuron

• dendrite: extensions of the cell body that receive neurotransmitters from pre-synaptic neurons and convert them into electrical chemical impulses that are then conducted towards the cell body

• axon: the long projection of a neuron that conducts electrical nerve impulses and carries them away from the cell body

• axon terminals: the end point of the axon branches that store neurotransmitters and release them into the synaptic cleft

• myelin sheath: fatty covering of the axon that acts as an insulator protecting the axon from stimuli that could interfere with transmission, and also assists with the speed of the electrical impulses

Functions of sensory, motor and interneurons

• sensory neurons: recieves sensory information from the sense organs or environment and carry the sensory messages to the spinal cord and the brain (the CNS)

• motor neurons: communicates information from the CNS to muscles, allowing for movement

• Interneurons: act as the connection between sensory and motor neurons, activated when sensory neurons receive intense sensory information, and coordinates the reflex arc

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Differences between neurons:

• sensory neurons: carry nerve impulses from a receptor to the CNS and have long dendrites and short axons, as the message is needed to move quickly (the shorter the axon the quicker the message moves through)

• motor neurons: carry nerve impulses from the CNS to an effector (muscle or glad) and have short dendrites and long axons (this provides the time to react, move and carry out that function)

• interneurons: found completely within the CNS and provide link within the CNS between sensory and motor neurons, and they also have short dendrites and long/short axons (depending on where they are located, what messages they’re sending etc, deciding if the message is required to be sent quickly or short.y), these are the only neurons found in the CNS as sensory and motor neurons are found within the PNS

questions:

1. the CNS consists of the vertebrae and the brain

2. the autonomic NS is responsible for funcitons such as breathing, heart beat etc. subconconscious things

3. the fight and flight response is from the sympathetic nervous system

Neural transmission:

Nerve impulses

• How nerves and neurons communicate with each other

• neurons form neural networks (neuron links) when axons from one neuron link with the dendrites of another neuron

• a nerve impulse is the message (electrochemical signal) that travels along the nerve fibre

• This is described as an electrochemical change because it involves a change in the electrochemical signal within the neuron, and neurotransmitters are the chemical component of the signal

• neurons communicate with eachother using a mixture of electrical and chemical signals

• an electrical signal is transmitted along the axon, and then chemical as its released as neurotransmitters

• only travels in one direction and is also known as action potential

what happens within the synapse is known as neurotransmittion

the synaptic cleft is the space between the synapse and the next neuron (pre-synaptic neuron and post synaptic neuron)

neural transmitters steps: where signals cross between neurons at the synapse

1. electrical nerve impulses (action potential) travel to the axon terminal in the presynaptic neuron

2. action potential causes neurotransmitters to be released from vesicles in the axon terminal

3. neurotransmitters diffuse across the clef/synapse and binds to receptors on the post synaptic cell

4. once enough receptors have neurotransmitters to bound to them, the signal is transmitted

Summary:

• role of the neurotrasmitter: act as the chemical messengerse. Allows neurons to communicate by relaying information between them across the synapse

• Electrochemical signal: the electrical nerve impulses are the electro component and neurotransmitters are the chemical component

• direction of transmission: one way, travelling from dendrites to the axon, and once its reached the axon terminals, it causes the release of neurotransmitters

• role of the synapse: the synapse allows neural transmission to occur by converting electrical nerve impulses from one neuron into a chemical signal and then back into electrical