neurons (4)

the human nervous system (3 main functions)

receives and processes information, and initiates a response to information

the human nervous system (what is it?)

a complex, highly organized network of specialised cells that enable the brain to receive information about what is going on from both inside and outside the body, and to respond appropiately

what does the human nervous system consist of?

consists of billions of neurons and glial cells that pass messages from the body to the brain and from the brain to the body

neurons

primary functional units (building blocks) of the brain and nervous system

individual nerve cell

involved in the reception, processing and transmission of information throughout the nervous system

neurons (communication, neurotransmission…)

communicates with each other and also with muscles and glands,

3 main types of neurons

motor neurons, sensory neurons, and interneurons

motor neurons

carry motor messages from the CNS to the skeletal muscles, organs and glands…also called efferent neurons or motorneurons

interneurons

send messages between sensory and motor neurons within the CNS, carry sensory messages to the brain via afferent tracts, carry motor messages to the motor neurons via efferent tracts

sensory neurons

receive and carry sensory information from internal and external environment to the CNS, also called (afferent neurons or affector neurons)

parts of a neuron (in order)

dendrites, soma, nucelas, axon, nodes of ranvier, myelin sheath, vescicles, axon terminals, synapse

dendrites, what do they detect and receive?

detect and receive information from other neurons and pass it to the soma

dendrites, what do they contain?

contains outshoots called dendritic spines or filagree, which have receptor sites to receive incoming information, each neuron can have one or many dendrites

soma

cell body that collects and integrates information from thousands of other neurons and then transmits it along the axon

nucleas

located in the soma, ‘brain’ of the cell

axon

single, tube-like extension that carries the action potential and transmits information to other neurons, can be short or long, nerves are made up of bundles of axons

nodes of ranvier

small gaps in the myelin sheath along the axon, neural impulse hops from node to node

myelin sheath

white fatty substance made up of schwann cells that surround and insulate axon, prevents interference from nearby axons and increases speed of neural transmission

vescicles

small sacks contained in the axon terminals that store and secrete neurotransmitters into the synaptic gap

axon terminals

contains a knob like swelling at the end called a terminal button/synaptic button

synapse

small space between the axon terminals of the presynaptic neuron and the dendrites of the post synaptic neuron, 500x thinner than a strand of hair

the synapse, axon terminal (function)

receives action potential which act on the vesicles

the synapse, vescicles (function)

move towards the membrane and release neurotransmitters into the synaptic gap

the synapse, neurotransmitters (function)

carry chemical messages across the synaptic gap and bind to receptor sites on the post synaptic neuron or are reabsorbed back into the terminal buttons through reuptake

the synapse, receptors (function)

receive the neurotransmitters and are either excited (firing a new action potential) or inhibited (stopping an action potential from firing)

action potential

An electrical signal that is generated in the soma and passes down the axon to the axon terminals