nervous 1 Flashcards
what is the simpilest form of nervous sytem
nerve nets, present in most animals
what type of nervous sytem do vertebrates have
nerve plexus
what is the diffrence between the central and periphiral nervous system
central are the brain and the spinal chord only. the peripherial system is the motor neuron and nerve fibers
what is the somatic nervous sytem responsible for
controls the volantary movments
what is the autonomic system resposible for
Control involantary responses, these include the parasympathetic and sympatheic system
what is the parasympatheic nervous system responsible for
‘fight or fligh’
what is the sympatheic nervous system responsible for
‘rest and digest’
descibe the structure of a neuron cell
The nucleus lies inside of the dendrites (signal recivers) and cell body, then the axon, which is sometimes surronded by a mylin sheath once past the axon hilock. finally the axon terminal releases the signal.
list the four structural types of neuron cells and define them
unipolar - only one extention
bipolar - two diffrent process that extend in opposite direction
pseudounipolar - only a sensory neuron
multipolar - possess a single axon with plently of dendrites, this allows for many differing connecting neuons.
what are the three functional classification of neurons
sensory
motor
interneuron
what are neuroglia
glial cells
- occupy half of the volume of the brain they serve as connective tissue in the CNS. they maintain the ECF enviroment surronding the neurons to modulate synaptic function. these arec rucial to memory and learning.
what are Astrocytes
apart of the CNS they support neurons in development, repair ect.
what are oligodendrocytes
they form the myelin sheath
what are ependymal
they form cerebrospinal fluid
define microglia
they provide an immune system for the CNS
define polarisation
charges are separated across the plasma membrane
define depolarization
Membrane is less negative as there is a decrease isn potential (+30 to +40 mV)
define replarization
Membrane returns to resting potential after being depolarized (-70mv)
define hyperpolarization
membrane is more negative than the resting potential (-80mv)
how is the membrane conentration impacted by the action potential
When the action potential is reached by the chemical messages arriving at the dendrites the ion channels/gates open and the ion can move and there is an influx of Na+ via rapid diffusion. This changes the membrane polarity to depolarization.
how is the membrane conentration maintained
Na+/K+pump which ensures that for every 3 Na leaving the membrane 2 K enter the cell.
give a description of action potentials
Occurs due to ion movement. The action potentials are brief, rapid and occur when the threshold potential is reached, otherwise no reaction will happen, there are no weak potential, only all or nothing.
what phases does the membrane potential undergo when given ample ions (ation potential)
- polarisation
- action potential initiates depolarization
- repolarisation
- hyperpolarization
what impactes the rate of impulses
axon diameter (larger is faster due to lack of resistance)
Presence of a myelin sheath
what are the types of propagate and describe them
- Continguous conduction
- neurotransmission of action potentials along a bear fibre such as parts in the CNS. - Saltatory conduction
- the current jumps from each node to the next due to the myelinated sheaths as they are fatty insulators and cannot conduct electricity. This is significantly faster.
what are the nodes of ranvier
exposed regions between the myelin sheaths of which are about 1 mm and contain a high concentration of Na+ channels which are voltage gated.
What is released from the axon terminal?
Acteylcholine
