Ch 48 pt A Flashcards
What is the CNS? What does it contain?
Central Nervous System
Brain and nerve cord
Spinal cord in vertebrates
What is the PNS? What does it contain?
Peripheral Nervous system
All neurons and projections of their plasma membrane that is outside of CNS
What are neurons?
Cells that send and receive electrical and chemical signals to and from other neurons throughout the body
What animals don’t have neurons
Sponges
What does the number of neurons depend on?
Size and behavioral complexity
What are the 3 parts of a neuron?
1) Soma (cell body)
2) Dendrites
3) Axon
What does the soma contain?
Nucleus and organelle
elle
diminutive
Characteristics of dendrites? (3)
1) Extensions of plasma membrane
2) Single or branching
3) Receives incoming signals
What is the function of axons?
send signals
characteristics of axons (4)
1) Extension of plasma membrane (neurolemma)
2) Single
3) Axon hillock near cell body
4) Axon terminal: convey electrical or chemical signals to other cells
What is neurolemma?
Outer portion of myelin sheath created by schwann cells
What is the function of axon terminals?
Convey electrical or chemical message to other cells
characteristics of Glia Cells (3)
1) Various functions
2) More than neurons
3) May function as stem cells giving rise to more glial cells and neurons
What are the 6 different types of glia cells?
1) satellite (PNS)
2) schwann (PNS)
3) Oligodendrocytes (CNS)
4) Astrocytes (CNS)
5) Microglia (CNS)
6) Ependymal cells (CNS)
What are the functions of satellite cells? (2)
1) surround neuron cell bodies in ganglia
2) regulate oxygen, carbon dioxide, nutrients, and neurotransmitters
What is the function of Schwann cells? (3)
1) Surround axons in PNS
2) Myelinate peripheral axons
3) Participate in repair after injury
What is the function of oligodendrocytes? (2)
1) myelinate CNS axons
2) provide structural support
What is the function of Astrocytes? (6)
1) metabolic support
2) blood brain barrier
3) structural support
4) regulate ion, nutrient, and dissolved gas concentrations
5) absorb and recycle neurotransmitters
6) form scar tissue
Astro
star
cyte
cell
What is the function of Microglia? (1)
Remove cellular debris, waste, and pathogens by phagocytosis
micro
little
glia
glue
What is the function of ependymal cells? (2)
1) Line ventricles and central canal
2) produce, circulate, moniter cerebral spinal fluid
What is myelin sheath interrupted by?
Nodes of ranvier
What produces myelin sheath
Oligodendrocytes (CNS)
Schwann Cells (PNS)
Dendro
tree
oligo
few
cyte
cells
Where are myelinated axons located?
white matter
Where are unmyelinated axons located?
grey matter
What does the Synaptic terminal do?
passes info (neurotransmitters) across synapse
What is the synapse
junction between axon and cell
What is the synaptic cleft?
space in between nueron and cell
Info is passed from _______ cell to the _______ cell
presynaptic; postsynaptic
Which cell is a Presynaptic cell?
neuron
Which cells are postsynaptic cells? (3)
1) neuron cell
2) muscle cell
3) gland cell
3 types of neurons
1) Sensory neurons
2) Motor neurons
3) Interneurons
Characteristics of Sensory Neurons (2)
1) Detect info from outside world and internal body condition
2) AFFERENT neurons transmit to CNS
Where are sensory neurons located?
in the Dorsal root
Afferent
bring to or lead toward
Characteristics of Motor Neurons (2)
1) Send signal away from CNS
2) EFFERENT neurons to elicit response
Where are motor neurons located?
in the ventral root
Efferent
conduct away or carry off
What is the function of Interneurons?
Form connections between other neurons in the CNS
Where are interneurons located?
CNS
Inter
Between
What is another name for the synaptic knobs?
telodendria
Characteristics of the Reflex arc (2)
1) Stimulus from sensory neurons to CNS to motor neurons to elicit response
2) Quick and automatic
What is Membrane potential?
difference in charge inside and outside the cell
(Polarized)
What is membrane potential determined by?
ion concentrations separated by plasma membrane
What is Resting membrane potential?
membrane potential when neurons not sending signals (-70mv)
Plasma membrane permeable ability to cations and anions?
Not very permeable
Separates charges by keeping different ions largely inside or outside cell
Voltage of resting potential inside cell
-70 mv
interior more negative than exterior
Where are negative ions within a cell drawn to?
Positive ions arrayed on outer surface
3 factors that affect resting potential
1) Na/K ATPase (sodium-potassium) pump
2) Ion specific channels allow passive movements of ions
3) Negatively charged molecules such as proteins more abundant inside cell
membrane more permeable to what ion at rest
K+
How does the number of K+ channels compare to Na+ channels?
More ungated K channels than ungated Na channels
explain transport of solutes in a sodium-potassium pump
3 Na+ out for every 2 K+ in
Explain how scientists measure membrane potential
voltmeter with microelectrodes inside and outside of a squid giant axon
measurement made as function of time
explain electrogradient
movement to balance out charges
explain chemical gradient
movement to balance out a specific ion
What is Equilibrium potential?
Opposing forces of chemical and electrical gradients can create an equilibrium where there is no net movement
All cells have?
Membrane potential
What are the only cells that can be excitable? (2)
What does excitable mean?
Nuerons and muscle cells
capacity to generate electrical signals
What are the 3 types of gated ion channels?
1) Voltage-gated
2) Ligand Gated
3) Mechanically gated
Changes in membrane potential are changes in?
Polarization
When cell membrane less polarized, less negative relative to surrounding solution?
Depolarization
Gated channels allow diffusion of what to cause membrane potential to become more positive
Na+
Cell membrane more polarized, more negative relative to surrounding solution
Hyperpolarization
Gated channels allow diffusion of what to cause membrane potential to become more negative
K moves out of cell making the cell membrane less positive
What are the 2 types of changes in membrane potential?
1) graded potential
2) action potential
What are the 2 types of graded potentials?
1) depolarization
2) hyperpolarization
What does the strength of graded potential rely on?
strength of stimulus
Where are graded potentials located?
Occur locally on dendrites or cell body
Why are graded potentials considered graded?
they travel a short distance then die out
What is the function of graded potentials in signaling?
acts as a trigger for action potentials
What are the characteristics of action potentials? (3)
1) carry electrical signals along axon
2) all or none
3) actively propagated