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Flashcards in Ch3-P61-65 Deck (30):

Neurons information

Cell specialised to receive, process, and/or transmit information to other cells in body.

200 different types of neurons that vary in shape, size, chemical composition and function but all have same basic structure. 

At least 100 billion neurons in typical adult brain.


Neuron picture


Neuron in words

Dendrite takes signal, through nucleus, along axon which is covered in myelin sheath which is made of cells call Schwann cells and each sheath is separated by Node of Ranvier, then this goes to Axon Terminal to go to next cell


Neuron cell body is called what and what does it contain?

Soma and it contains nucleus and cytoplasm


Length of axon

In brain less than a millimetre but in the spinal cord it can be several feet long


Neuroscience defined

the scientific study of the brain and of the links between brain activity and behaviour


Dendrites are?

The branched fibres of neurons that receive incoming signals


Soma is?

The cell body of a neuron, containing the nucleus and cytoplasm


Axon is?

The extended fibre of a neuron through which nerve impulses travel from the soma to the terminal buttons


Terminal buttons are?

The bulb like structures at the branched endings of axons that contain vesicles filled with neurotransmitters


Sensory neurons are?

The neurons that carry messages from the sense receptors towards the central nervous system


Motor Neurons are?

The neurons that carry messages away from the central nervous system towards the muscles and glands


Interneurons are?

Brain neurons that relay messages from sensory neurons to other interneurons or to motor neurons


Glia is? (textbook answer)

The cells that hold neurons together and facilitate neural transmission, remove damaged and dead neurons and prevent poisonous substances in the blood from reaching the brain


Glia cells wikipedia

Glial cells, sometimes called neuroglia or simply glia are non-neuronal cells that maintain homeostasis, form myelin, and provide support and protection for neurons in the brain, and for neurons in other parts of the nervous system such as in the autonomic nervous system.
Glia are commonly known as the glue of the nervous system; however, this is not fully accurate. Neuroscience currently identifies four main functions of glial cells: to surround neurons and hold them in place, to supply nutrients and oxygen to neurons, to insulate one neuron from another, and to destroy pathogens and remove dead neurons. They modulate neurotransmission, although the mechanisms are not yet well understood.


Glia cells what they do? textbook

Glia is Greek for glue. Provide scaffolding and structure to hold neurons in place. During development glial cells guide newborn neurons to appropriate locations in the brain. Glial cells housekeep and clean up dead and damaged neurons. Also take up excess neurotransmitters and other substances at the gaps between neurons. Glial cells also form myelin sheath around some types of axons.


Myelin sheath is?

insulating material that surrounds axons and increases the speed of neural transmission


Excitatory inputs are?

information entering a neuron that signals it to fire


Inhibitory inputs are?

Information entering a neuron that signals it not to fire


Action potential is?

the nerve impulse activated in a neuron that travels down the axon and causes neurotransmitters to be released into a synapse

The right balance of excitatory and inhibitory inputs will lead to the production of an action potential: the neuron fires


Resting potential is? (textbook)

The polarisation of cellular fluid within a neuron, which provides the capability to produce an action potential


Action Potential (wikipedia) is?

a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a consistent trajectory. Action potentials occur in several types of animal cells, called excitable cells, which include neurons, muscle cells, and endocrine cells, as well as in some plant cells.


Action Potential diagram


action potential steps in words

1. Resting state. Fluid inside axon is polarised with respect to exterior fluid providing restng potential

2. Stimulus received. Na+ channels open. Na+ ions flow into axon causing depolarisation. Nerve impulse moves down the axon as each successive segment becomes depolarised

3. Once nerve impulse has passed Na+ flows back out of axon to restore resting potential

4. Ready to transmit another impulse


All or none rule

The rule that the size of the action potential is unaffected by increases in the intensity of stimulation beyond the threshold level.


Refractory period is?

the period of rest during which a new nerve impulse cannot be activated in a segment of an axon


Refractory period diagram


Synapse is?

The gap between one neuron and another


Synaptic transmission is?

The relaying of information from one neuron to another across the synaptic gap.


Neurotransmitters are?

The chemical messengers released from neurons that cross the synapse from one neuron to another, stimulating the postsynaptic neuron.