Nervous system

All neurons are myelinated. True/false?

false. Multipolar interneurons are not myelinated.

astrocyte

part of the blood-brain barrier, regulate cerebral blood flow, neurotransmitter release and uptake, metabolic and structural support, regulation of interstitial fluid ion composition

what do glial cells do?

physical/metabolic support, insulate axons with myelin, protection, release and clear neurotransmitters, maintain extracellular environment

macrophage

(macro = "large", phage = "eat") a type of white blood cell that ingests/gobbles up bacterial cells

the PNS can be divided into _ divisions, which are what?

2, afferent (sensory) and efferent (motor)

what is the difference between ATP synthase and ATPase?

ATP synthase makes ATP, while ATP synthase hydrolyzes (uses) ATP

How do action potentials jump between nodes of ranvier?

Because the cytoplasm of the axon is electrically conductive, and because the myelin inhibits charge leakage through the membrane, depolarization at one node of Ranvier is sufficient to elevate the voltage at a neighboring node to the threshold for action potential initiation. Thus in myelinated axons, action potentials do not propagate as waves, but recur at successive nodes and in effect "hop" along the axon, by which process they travel faster than they would otherwise.

myelin

an outgrowth of a glial cell made of a dielectric (electrically insulating) material that forms a layer (myelin sheath) around the axon of a nerve cell.

most common type of glial cell

astrocyte

what is the difference between an oligodendrocyte and a schwann cell?

both insulate neurons with a myelin sheath. however, oligodenrocytes ("oligo"="many/several") occur in the central nervous system (CNS) and extend to up to 50 axons, while schwann cells occur in the peripheral nervous system (PNS) and can only wrap around 1 axon.

what is the difference between the central nervous system and the peripheral nervous system?

central nervous system: brain and spinal chord peripheral nervous system: everything else with neurons

most recently in evolution, what has the nervous system in the human race provided?

cognition and emotion

clusters of neurons are called ____

ganglia

the nervous system of an earthworm consists of a segmental nerve cord with pairs of _____ going down it.

ganglia

microglia are a type of ___ cell that act in the ___ nervous system and provide ____ defenses, such as acting as _____ (white blood cells)

glial, central, immune, macrophages

Another important thing the nervous system does, (without you realizing it): cell communication for ___

homeostatic balance

brain

large, centrally located pair of ganglia

nervous system of a sea anenome:

nerve net

glial cells are differentiated from nerve cell because glial cells are_____, meaning _____

not excitable, they do not fire action potentials.

the most important aspect of the nervous system: (what does it do?)

responds to a rapidly changing environment.

at a synapse, the presynaptic neuron _____ the message, and while the post synaptic neuron ____ the message.

sends, receives

nerve net

simple network of neurons that forms direct lines of communication from sensory cells to effectors (muscles mostly)

why do squid have a more complex nervous system than earthworms?

squid have special ganglia that process and integrate information

If glial cells have so many different functions, why are they associated with the nervous system at all?

there are only two categories of cells in the nervous system: those that are neurons, and those that aren't--glia

nervous system of a sponge:

there is none.