nervous system Flashcards
what are the three main functions that maintain homeostasis in the nervous system?
- sensory function
- integrative function
- motor function
what does sensory function detect?
sensory input
what does integrative function analyse and interpret?
sensory input and determines appropriate responses
what does motor function issue?
motor output to activate an effector
what is sensory input detected by?
general and special sensory receptors
where are general sensory receptors located?
skin, skeletal muscles, tendons, joints and visceral organs
what are the types of general sensory receptors?
- thermoreceptors
- nociceptors
- mechanoreceptors
what do thermoreceptors detect?
changes in temp
what do nociceptors detect?
painful stimuli
what are the different types of mechanoreceptors?
- tactile receptors
- baroreceptors
- proprioceptors
what do tactile receptors detect?
touch, pressure and vibration stimuli
what do baroreceptors detect?
changes in blood pressure
what do proprioceptors detect?
changes in body position
where are special sensory receptors located?
eyes, ears, mouth and nose
what are the types of special sensory receptors?
- photoreceptors
- chemoreceptors
- mechanoreceptors called hair cells
what do photoreceptors detect?
light (vision)
what do chemoreceptors detect?
chemicals in solution (taste and smell)
what do special sensory mechanoreceptors (hair cells) detect?
hearing and balance stimuli
what is motor output?
activates a specific muscle or gland to cause a response
what does the CNS consist of?
brain and spinal cord
what does the PNS consist of?
sensory receptors and the cranial, spinal and peripheral nerves that link all parts of the body to the CNS
what are the two functional divisions of the PNS?
sensory and motor division
what does the sensory division convey?
sensory input from receptors to the CNS
what does the motor division convey?
conveys motor output from the CNS to a muscle or gland
what does the autonomic nervous system convey?
‘automatic’ motor output from the CNS to the body’s glands, cardiac and smooth muscles
what does the somatic nervous system convey?
‘somatic’ motor output from the CNS to body’s skeletal muscles
what does sympathetic division control?
‘fight or flight’ activities
what does sympathetic division activate?
activates body functions that support physical activity and inhibit those that don’t eg. increase heart rate
what are the two functional systems of motor division?
autonomic and somatic nervous systems
what are the two functional divisions of the autonomic nervous system?
sympathetic and parasympathetic division
what does parasympathetic division control?
rest and digest
what is neural tissue mostly composed of?
neuroglia and neurons
what are the two types of neuroglia found in the PNS?
- satellite cells
- schwann cells
what are the four types of neuroglia found in the CNS?
- ependymal cells
- oligodendrocytes
- astrocytes
- microglia
what are the four common parts of a neuron?
- dendrites
- cell body
- axon (fibre)
- axon terminals
are dendrites involved in short or long processes?
short
what is the main receptive area of a neuron?
dendrites
what does the dendrites convert info they receive into?
graded potential
where does graded potential generated by the dendrites travel to to be integrated?
cell body
where does the cell body convey info to after it is graded?
initial segment
what is the conducting region of a neuron?
axon
where are action potentials generated and conducted in a neuron?
axon
what does myelin increase?
speed of signal conduction
what are segments of myelin separated by?
bypasses called nodes of ranvier
what do axon terminal form with another cell?
synapse
what is the secretory region of a neuron?
axon terminals
what does the axon terminals contain?
contain synaptic vesicles which store and release neurotransmitters
what are neuron cell bodies clustered in the CNS called?
nuclei (nucleus)
what are neuron cell bodies clustered in the PNS called?
ganglia (ganglion)
what are neuron axons that are bundled together in the CNS called?
tracts
what are neuron axons that are bundled together in the PNS called?
nerves
what are the different structural classifications of neurons?
- multipolar
- bipolar
- unipolar
where are multipolar neurons found?
CNS and PNS
where are bipolar neurons found?
special sense organs (rare)
where are unipolar neurons found?
PNS
what type of structure are sensory neurons?
unipolar
what type of structure are interneurons?
multipolar
what do sensory neurons do?
conduct sensory input from receptors to the CNS
what do interneurons do?
conduct info within the CNS
what do motor neurons do?
conduct motor output away from CNS to a muscle or gland
what type of structure are motor neurons?
multipolar
what type of neurons conduct somatic motor output?
lower motor neurons
what type of neurons conduct automatic motor output?
preganglionic and postganglionic neurons
what does potential energy =?
voltage
is the interior of the membrane positive or negative?
negative
is the exterior of the membrane positive or negative?
positive
what is the membrane potential?
the potential energy separating the charges of the interior and exterior
when does a change in membrane potential occur?
when ions flow through specific ion channels across membrane
what are the two main types of ion channels?
leakage and gated channels
what are the types of gated channels?
- chemically
- mechanically
- voltage-gated channels
what does a chemically-gated channel open in response to?
a chemical stimulus eg. neurotransmitter
where are chemically-gated channels located on a neuron?
dendrites and cell body
what does a mechanically-gated channel open in response to?
a mechanical stimulus eg. touch, vibration and pressure
what does a voltage-gated channel open and close in response to?
voltage changes
where are mechanically-gated channels located on a neuron?
dendrites
where are voltage-gated channels located on a neuron?
axon and axon terminals
what is the resting membrane potential?
approx -70mV
what are the two types of signals of the nervous system?
- graded potential
- action potential (nerve impulses)
is a graded potential a short or long distance signal?
short
is an action potential a short or long distance signal?
long
where do graded potentials originate?
dendrites or cell body
what does the graded potential stimulate?
voltage-gated Na+ channels to open
where do action potentials originate?
initial segment
what type of gated channels are involved with graded potential?
chemically or mechanically-gated channels
what type of gated channels are involved with action potential?
voltage-gated channels
what happens to the membrane potential when depolarisation occurs?
becomes less negative
what is the threshold of depolarisation?
-55mV
what occurs at the threshold during depolarisation?
voltage-gated Na+ channels at initial segment open and Na+ ions diffuse into ICF
during repolarisation at a membrane potential of +30mV what occurs?
voltage-gated Na+ channels close and voltage-gated K+ channels open, K+ ions diffuse out of ICF
after K+ ions leave the ICF what happens to the membrane potential?
loss of positive ions returns the membrane potential to -70mV
what happens to the membrane potential during hyperpolarisation?
becomes more negative and shifts from -70mV to -90mV
what occurs during hyperpolarisation?
voltage-gated K+ channels slowly close
where does continuous conduction occur?
unmyelinated axons
where does saltatory conduction occur?
myelinated axons
where are action potentials generated in continuous conduction?
voltage-gated channels along length of axon
where are action potentials generated in saltatory conduction?
nodes of ranvier
