Nervous System Flashcards
function of nervous system
control and communicate
components of the nervous system
brain, Spinal cord and peripheral nerves
how is the nervous system set up to detect signals?
subdivided into smaller systems by locations ( Central and Peripheral)
- wants to detect internal and external environments, evaluate information and initiate response
what is the CNS
structural and functional centre of entire nervous system
- brain and spinal cord
what is PNS composed of
nerves that lie in the outer region
- cranial nerves nad spinal nerves
Somatic vs autonomic?
somatic control skeletal muscles (voluntary)
autonomic control involuntary muscles
afferent vs efferent divisions?
afferent division is incoming messages (arriving) from the visceral receptors and efferent is outgoing (exiting)
the autonomic nervous system efferent pathways are further divided into?
Sympathetic division
and parasympathetic
sympathetic
prepares body for fight or flight
parasympathetic
normal resting activities
- rest and repair
the distension of the stomach caused by the presence of food trigger the _______ to _________
parasympathetic, to increase secretion of gastric juice
Neurons vs Glial cells?
neurons- excitable cells that conduct impulses
glial cells- do not conduct info but support the function of neurons
glial cells- how many types in the CNS, how many in PNS?
do not conduct information, but support the function of neurons
- there are 4 major types of glial in the CNS (astrocytes, microglia, ependymal, oligodendrocytes)
- Schwann cells in the PNS
within the neutron what does axon transport look like?
cell body can make neurotransmitters, motor molecules move proteins on the cytoskeleton highway for the release at the synaptic knobs
Astrocytes?
star shaped and the largest and most numerous type of glial
- connect to neurons and capillaries
- transfer nutrients from the blood to the neurons
- form tight sheaths around brain capillaries, which, with tight junctions between capillary endothelial cells, constitute the blood- brain barrier (BBB)
what is purpose of the BBB
protects the brain from harmful substances in the blood stream while also allowing for supply of nutrients to the brain
how does the BBB protect the brain?
it strictly limits transport into the brain through both tight junctions and metabolic ( enzymes) barriers and a double barrier
what do astrocytes do for the BBB?
webs of astrocytes form tight sheets around the brains capillaries, this allows for a double barrier around the capillaries–> astrocyte feet and endothelial cells
conscious movements are controlled by?
somatic nervous system
how does sympathetic influence the liver and digestion/reproductive organs?
will “turn them off”/ decrease this activity as there are other priorities
Sympathetic nervous system and the heart
SA node ( pacemaker of the cell) when it receives Sympathetic stimulus–> increase heart rate
what can cross the BBB?
liposomes ( vesicle with a membrane composed of a PPL bilayer)
gases, lipid soluble, glucose and other harmful things as well
benefit of liposomes passing through the BBB
deliver drugs or genetic material into the cell
Microglia are _______ of the brain
macrophages of the brain
-small, usually stationary cells
act as scavengers (modified immune cells)
what cannot diffuse the BBB?
water soluble, need specialized transporter
Ependymal cells
Ep-i-dime-al
- create barriers (protection) between compartments and are sources of neural stem cells
resemble epithelial cells and form thin sheets that line fluid-filled cavities ( cerebral-spinal fluid) in the CNS - some produce fluid others aid in circulation of fluid
Oligodendrocytes
- form myelin sheaths
are smaller than astrocytes
Multiple sclerosis is a disorder of _____
oligodendrocytes
- most common disease od the CNS
- myelin loss and destruction, exposed nerve fiber
- plaque like lesions form
- failure in nerve conduction
- communication is impaired
Glial cells of the PNS (2)
Schwann cells and a subcategory of satellite cells
Schwann cells
found only in the PNS (they can be thought of as the functional equivalent of the oligodendrocyte)
- support nerve fibres and in some cases form myelin sheath
Satellite cells
are another type of Schwann cell that cover and support neutron cells in the PNS BUT they do NOT form myelin sheath
grey fibres vs white fibres?
grey= Schwann cells not forming myelin sheath yet still supporting a bundle of nerves white= Schwann forming myelin sheath
Myelin sheath consist of ?
many layers of Ppl and cell membranes
it wraps around an axon
the Schwann cell nucleus is not included
summation zone of a neutron is characterized by?
axon hillock which serves as the site where the nerve impulses combine and may trigger an action potential to be conducted along the axon
the functional region where the axon has many voltage gated channels ?
Conduction zone
the functional region where the synaptic knob of the axon is located?
Output zone
the functional region of the axon where the axon hillock is located?
Summation zone
afferent neurons conduct
incoming sensory impulses that go to brain or/and spinal cord
(Afferent arrives, Efferent Exists)
efferent conduct?
impulses away from the brain and spinal cord toward muscles (outgoing impulses)
Interneurons lie only in the?
CNS and they conduct impulses from afferent to motor neurons
what is the difference between nerves and tracts?
Nerves belong to PNS whereas Tracts belong to the CNS
- they are both bundles of nerve fibres ( bundles of axons)
why is nerve damage irreversible?
mature neurons are incapable of cell division
the interior of the cell is pos or neg compared tot he outside in nerve cells?
negative about -70 mV
what cation is a primary determinant of RMP?
sodium
- actively transported out of cell to create a concentration gradient with interior more negative
sodium/ pump role in RMP
pumps 3 NA+ out but only 2 K+ in
in depolarization the membrane potential becomes ?
less negative
in hyper-polarization the membrane potential becomes?
even more negative
what can cross the BBB? what cannot?
can- lipid soluble
can’t-water soluble (unless has a specialized carrier
which 2 CNS can be a source of neural stem cell?
Astrocytes and ependymal
Schwann cells are found only in?
PNS
Schwann cells in the PNS are comparable to ______ in the CNS in function
oligodendrocyte
another type of cell that covers and supports neutron cells bodies in the PNS
Satellite cells ( type of Schwann )
epineurium
surround the nerve
perineurium
surround the fascicle of axons
endoneurium
surrounds each individual axon within a fascicle
- fascicle surrounded by perineurium
- epineurium surrounds the whole thing
gated channels can be?
voltage gated, chemical gated, mechanically gated
action potenical is a change in?
RMP
threshold potencial
the min magnitude of a voltage fluctuation that will trigger the opening of a voltage gated channel
stimulus of a neuron can fluctuate _____ or _____ RMP
above or below
excitation of a neuron occurs when a stimulus?
trigger the opening of additional Na+ channels–> more Na+ to move INSIDE depolarization (more toward zero)
inhibition of a neuron
addition of K+ channels allows K+ to diffuse OUTSIDE ( with gradient)
this results in hyper polarization - more negative
after the action potenicial peaks, how does the membrane go back to RMP?
opening K+ channels, allowing outward diffusion of K+= depolarization
what does refractory period ensure that?
action potential never goes backwards
how many neurotransmitters?
30 known
the function of the neurotransmitter is determined by?
the postsynaptic receptor
excitatory its
release neurotransmitters
inhibitory nts
inhibit release of neurotransmitters
neurotransmitter action is terminated by?
enzymes
re-uptake
acetylcholine is recycled, discribe the process
acetylcholine esterase breaks down into choline and acetate
temporal
same stimulus but within a critical time - back to back
- same person running with one bucket back and forth to fill a bathtub
spacial
all at the same time but different sources
- five people all dump five buckets of water into a bathtub at the same time
