The Nervous system Flashcards
how does the nervous system ensure homeostasis is preserved
detects stimuli occuring inside and outside the body
responds to these changes
coordiantes activities in the organ systems
what are the 3 main functions of the Nervous System
sensory
integrative
motor function
what does the sensory function of the nervous system involve
detects sensory input
sends sensory input to the control centre
what does the integrative function of the nervous system involve
analyses and interprets sensory input
determines approprriate response
generates motor output that causes response
what does the motor function of the nervous system involve
issues motor output to activate an effector
what stimuli do nociceptors detect
pain
what do tactile receptors detect
touch, pressure and vibration
what do baroreceptors detect
change in BP
What do proprioreceptors detect
body position
what do photoreceptors detect
light
what do chemoreceptors detect
chemicals in solution ( taste and smell)
what do mechanorecptors detect
hearing and balance
list the 2 divisions of the nervous system
Central and peripheral
what does the CNS consist of
brain and spinal cord
the control centre performs what main function
integration
what are the 2 main divisions of the motor division
autonomic and somatic
conveys somatic motor output from the _______ to the skeletal muscles
CNS
the autonomic motor output control involuntary activities such as: (5)
heart rate resp. food digestion urination/ defication BV and pupil diameter
name the 2 functional divisions of the autonomic nervous system
sympathetic and parasympathetic
neural tissue mostly consists of 2 cell types, name them
neuroglia
neurons
name the 2 types of neuroglia that can be found in the PNS
satellite cells
schwann cells
name the 4 different types of neuroglia that can be found in the CNS
ependymal cells
astrocytes
oligodendrocytes
microglia
what do neurons require for survival
oxygen and glucose
what is the main function of neurons
communication
name the 4 parts most neurons consist of
dendrites
cell body
axon
axon terminals
Dendrites are the main _____ input region of a neuron
input
what does the cell body contain
nucleus and organelles
what are the 2 main function of the cell body
receive info from other neurons and converts this info into a graded potential.
integrates info and conveys it towards the initial segment of the axon
what is the axon covered by
myelin sheath
where is the myelin sheath produced
schwann cells and oligodendrocytes
what is the function of myelin
increases the speed of signal conduction
what are the gaps in the segments called
nodes of ranvier
destruction of myelin in the CNS results in which condition
MS
What do axon terminals contain?
synaptic vesicles
what do synaptic vesicles store and release
neurotransmitters
what is the function of neurotransmitters
chemicals that carry info from a neuron to another cell
neuron cell bodies are organised into clusters called:
in the CNS
in the PNS
nuclei
ganglia
neuron axons are bundled together to form
in the CNS
in the PNS
tracts
nerves
what are the 3 classifications of neurons
- multipolar
- bipolar
- unipolar
particles can be ____/____ charged
positively or negatively
for neurons to generate an electrical signal, their plasma mem must:
- exhibit a resting membrane potential (RMP)
- contain protein channels which allow specific ions to diffuse down their concentration gradient
compare leakage channels and gated channels
leakage: always open
gated: open and close in response to a specific stimulus
where would chemically gated channels be located
along the plasma membrane of the dendrites and cell body
where would one find mechanically gated channels
along the plasma membrane of dendrites
where are voltage gated channels found
along the PM of the axon and axon terminals
what is a resting membrane potential
voltage across the plasma membrane of a resting cell.
what causes a RMP to exist
uneven distribution of positive ions across the plasma membrane creates a charge difference across the membrane
what is the approximate voltage of a RMP
-70mV
what is depolarisation
occurs when the membrane potential becomes less negative
what happens when a stimuls opens sodium gated channels
- influx of sodium ions into the ICF
- ICF gains postive ions
- cell interior becomes less negative
- membrane potential becomes less negative
what is hyperpolarisation
membrane potential becomes more negative
what happens when a stimulus opens potassium gated channels”
- efflux of potassium ions out of the ICF
- ICF looses positive ions
- cell interior becomes more negative
- membrane potential becomes more negative
what are the 2 types of electrical singnals that the nervous system generates
- graded potentials
- action potentials
what are the graded potentials
small changes in the membrane potential
where do graded potentials originate
in the dendrites or cell body when a stimulus opens chemically gated or mechanically gated channels.
state the length of graded potentials
short
describe the process of a graded potential
- travel to the initial segment of an axon
- depolarise the initial segment to -55
stimulates voltage gated sodium channels to open - generates an AP
compare continuous conduction with saltatory conduction with regards to:
- where it occurs
- whether the action potentials are generated
- conduction speed
unmyelinated axons // myelinated axons
voltage gated channels along the length of the axon // generated at the nodes of ranvier
< 2m/s // >100m/s
explain how a local anesthetic blocks pain
- block voltage gated sodium channels
- no action potential
- no conduction of pain signal to the brain
- no sensation of pain
why does the cold and pressure reduce pain
impairs signal conduction
what is a chemical synapse
junction that mediates the transfer of info
what process occurs at a chemical synapse between 2 neurons
- neurons sending the info - presynaptic neuron
- neuron receiving the info - postsynaptic neuron
- presynaptic and postsynaptic membranes and seperated by synaptic cleff.
- signal transmission involves chemical neurotransmitters.
