Nervous system, neurons, synapses Flashcards
2 Main functions of nervous system
To collect, process and respond to info in the environment.
To coordinate the working of different organs and cells in the body.
Define Nervous system
A specialised network of cells in the human body. it is our primary internal communications system based on electrical and chemical signal
Structure of the nervous system
Central nervous system - brain and spinal chord (a bundle of nerves which connects nearly all parts of the body to the brain)
Peripheral - All other nerves
- Divisions of peripheral
Peripheral - Transmits messages via neurons to and from the CNS
- Somatic
Controls muscle movements and recieves information from the sensory receptor.
Voluntary control over skeleton and muscles.
Carries commands from motor cortex (controlled from) and has sensory and motor pathways
- Autonomic
Vital functions like breathing, stress and heart rate.
automatic/involuntary control.
controlled by brain stem and only has motor neuron pathways.
- Sympathetic
Stimulates functions like digestion, gets ready for action
- Parasympathetic
Slows functions like digestion involved in ‘rest and digest’ calms down.
Homeostasis
The two systems SYMP and PARA interact to create homeostasis. their actions are mostly antagonostic, work in opposition to eachother. a normal balance of both is called maintaining homeostasis.
Definition of neuron
Cells that make up nervous system. Conduct electrical impulses which transmit messages around the body
Dendrites
Recieve signals from other neurons or from sensory receptor cells. Dendrites connected to cell body which contains the nucleus.
Axon
The axon is a long slender fibre tht carries nerve impulses in the form of an electrical signal (action potential). Most are sourrounded by a myelin sheath (except for relay) insulating neuron for a faster impulse.
Node of ranvier
A node of ranvier is a periodic gap in sheath that make the electrical impulses jump quicker as the consistency of them increases conduction velocity
Schwann cell
Schwann cells wrap its plasma membrane concentrically around the axon and form the myelin to form the myelin sheath
Axon terminal
Make synaptic connections with another neuron. Triggers movement of vesicles towards membrane.
Action potential
How information is transmitted within the neuron.
The dendrites of the neuron recieve information from sensory receptors or other neurons. This excites the neurons causing sodium ions to enter the membrane. This information is carried in vesicles and passed down to the cell body and onto the axon. Once info arrives at axon, it travles down its length in electrical signal known as action potential.
Types of neuron - Relay
Between sensory and motor. located in brain and spinal chord. (interneuron) allows sensory and motor to communicate. Short dendrite short axon
Types of neuron - Sensory
From sensory register to CNS. In Peripheral NS. Goes towards brain. Sends signal from senses to CNS. Dendrite long axon short
Types of neuron - Motor
From CNS to effector to promote movement. Located in cell body of motor neuron and part of the peripheral. Denderite short. Axon Long.
Types of neuron - Motor
From CNS to effector to promote movement. Located in cell body of motor neuron and part of the peripheral. Denderite short. Axon Long.
Transmission of neuron
- receptors in the skin detect a stimulus
- sensor neuron sends electrical impulses to a relay neuron which is located in the spinal chord of the CNS
- motor neuron sends electrical impulses to effector
- effector produces a response
Synaptic Transmission
neurons communicate with each other within groups known as neural networks. Each neuron is seperated from the next by a tiny gap called the synapse.
Signals within neurons are transmitted electrically. Signals between neuron are transmitted chemically across the synapse. These chemical messengers are known as neurotransmitters.
Synaptic Transmission
neurons communicate with each other within groups known as neural networks. Each neuron is seperated from the next by a tiny gap called the synapse.
Signals within neurons are transmitted electrically. Signals between neuron are transmitted chemically across the synapse. These chemical messengers are known as neurotransmitters.
Ex of neurotransmitters
Serotonin - mood, sleep, eating
Dopamine - motivation, movement, attention, learning
GABA - little linked to anxiety disorders
Noradrenaline - associated with fight or flight, Sz
