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)

Nervous System Flashcards by Cailyn Strachan

function of nervous system

control and communicate

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components of the nervous system

brain, Spinal cord and peripheral nerves

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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

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what is the CNS

structural and functional centre of entire nervous system

- brain and spinal cord

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what is PNS composed of

nerves that lie in the outer region

- cranial nerves nad spinal nerves

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Somatic vs autonomic?

somatic control skeletal muscles (voluntary)

autonomic control involuntary muscles

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afferent vs efferent divisions?

afferent division is incoming messages (arriving) from the visceral receptors and efferent is outgoing (exiting)

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the autonomic nervous system efferent pathways are further divided into?

Sympathetic division

and parasympathetic

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sympathetic

prepares body for fight or flight

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parasympathetic

normal resting activities

- rest and repair

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the distension of the stomach caused by the presence of food trigger the _______ to _________

parasympathetic, to increase secretion of gastric juice

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Neurons vs Glial cells?

neurons- excitable cells that conduct impulses

glial cells- do not conduct info but support the function of neurons

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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

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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

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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)

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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

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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

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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

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conscious movements are controlled by?

somatic nervous system

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how does sympathetic influence the liver and digestion/reproductive organs?

will “turn them off”/ decrease this activity as there are other priorities

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Sympathetic nervous system and the heart

SA node ( pacemaker of the cell) when it receives Sympathetic stimulus–> increase heart rate

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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

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benefit of liposomes passing through the BBB

deliver drugs or genetic material into the cell

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Microglia are _______ of the brain

macrophages of the brain
-small, usually stationary cells
act as scavengers (modified immune cells)

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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