Exam 2: Chapter 12: Neurons Flashcards
Whole-animal integration involves the combination of:
sensory, endocrine, and CNS information processes
What systems work together in different manners to control cells?
nervous system and endocrine system
Neuron communication (3 basics)
send electrical signals down axons to target cells; communication is fast and the distance is determined by the length of the axon
Signals transmitted to target cells will…
cause a response perhaps activating or inhibiting action of the cell
endocrine cell communication (3 basics in comparison to neuron communication)
hormones enter the blood stream and travel to a target cell; action is slow and can travel anywhere that blood vessels go
cells that are contacted by hormones must have
receptors for that specific hormone
target cells of hormones respond according to
the nature of the signal
neurons carry…
self-propagating electrical signals called action potential to their contacts
neuron signals are received at the _____
sypase, often present on dendrites
neurotransmitters travel across the _______
synaptic cleft between cells
neuron signals typically start where
cell body or soma
central nervous system (CNS)
consist of both the brain and the spinal cord
peripheral nervous system (PNS)
consists of all nerves outside the CNS
afferent neurons
sensory neurons that carry data to the CNS
efferent neurons
start in the CNS and send instructions to target cells (muscles)
interneruons
interface between sensory and motor neurons; only in the CNS in the gray matter of the spinal cord
Signal may take ________ ms, and may have ____ signals per second
2-100ms, 100 per second
Neuron signals provide what type of communication
spatial and temporal
Hormones only have action with
cells and tissues with receptors for that hormone on thier surface
how a target cells responds is generally by….
gene expression
Nervous system controls:
fast, fine, specific muscle movements
Endocrine system controls:
broad, longer actions like metabolic events
Steps of the nervous system circuit/organization
- a stimulus starts a reflex which begins a series of action potentials in sensory neurons
- the action potential travel on afferent axons of sensory neurons to the CNS, excitatory contacts are made to interneurons
- interneurons generate their own action potential
- connect to efferent motor neurons who send axons to make contacts to muscles
- response is produced
Reticular theory:
nervous system cells run together without boundaries
neuron doctrine:
neurons are anatomically distinct and are structural, functional, and developmental units of nervous system organization
the type of neurons depends on…
the number of processes emanate from it’s soma
dendrites are…
the receptive or input element, carrying infomartion to the soma
axons are…
the output element, carrying information away form the soma to other cells
myelin
comes from the glial cells, insulates axons allowing them to transmit neuronal signals quickly and with minimal signal lost
myelin is present in which types of animals
vertebrates (absent in invertebrates)
without myelin, signaling down an axon would be
slower and would diminish with distance traveled
glial cells
support neurons physically and metabolically
what are the two types of glial cells?
schwann cells (PNS) and oligodendrocytes (CNS)
oligodendrocytes
the myelinating cells of the central nervous system (CNS)
astrocytes
located near to capillaries; acting as intermediates between the blood vessels and neurons; take up neurotransmitters and supply metabolic substrates to neurons; also have a roll in nervous system development and control extracellular ion levels
microglia
control immune actions in nerve cells
cell membranes
have passive electrical properties; resistance and capacitance
all cells respond to….
electric currents, but only neuronal cells generate action potentials
resting membrane potential (Vm)
the potential difference across the membrane
Inside of the membrane is
less positive
membrane resistance (Rm)
prevents ions from moving across the membrane
an action potential results in
membrane depolarization; inside becomes more positive
hyperpolarization
returns the membrane to its resting potential
The nernst equation
membrane potentials depend on the selective permeability of ions; helpful to understand the relation between the concentration differences of a permeating ion across a membrane and the membrane potential equilibrium
E=(RT/zF)ln(Cout/Cin)
Inside the cell:
high concentration of K+ and negatively charged anions (A-)
outside the cell:
high concentration of Na+
the cell membrane is permeable to:
K+
What causes the membrane potential to develope?
some K+ leaves the cell with the concentration gradient
larger concentration difference across the membrane will result in
greater membrane potential
ion concentration differences result from
active ion transport and from passive diffusion
All cells keep the following concentrations
greater potassium level and a lesser sodium and chloride lever inside than outside
the different ion concentrations between in and out of a cell is caused by
some ions are actively transported and others are passively moved
Na+ and K+ exchange pump
ratio of 3 to 2 (3 sodiums out for every 2 potassium ions brought in), helps maintain the negative potential
goldman equation
takes into account 2 ions at a time so it is more accurate
The K+ level determines the resting membrane potential because
K+ is more permeable
the action potential
occurs in excitable cells; voltage dependent, all or non signals; caused by voltage dependent changes in membrane permeabilities to ions
ion channels are
voltage gates
action potential starts with
depolarization
what is resting membrane potential
-65mV
Action Potential
review slides from chapter 12 powerpoint
nodes of ranvier
gaps in the myelin sheath coating on the neural axon; allows the electrical impulse to move quickly down the axon
Integration of cells involves
events within cells
Control comes from the brain with….
sensory neurons providing feedback from sensory input
Neuronal signals are …….
Fast and addressed
Neurons provide connections to….
Very specific locations
Endocrine cells …..
Broadcast hormones
Where are hormones sent? What does this mean?
Hormones are sent wherever blood flows, so it is less specific
Although the nervous systems and endocrine systems tend to control different processes, both systems can exert control over each other. Give an example
Nerves can control glands and sex hormones can effect neurons in the brain
What are the 3 main theories that concern cellular organization?
Cell theory, reticular theory, and the neuron doctrine
What does the cell theory state?
Organisms are made of cells and cells come from preexisting cells
Neurons generally have what in terms of structure?
An axon and one or more dendrites
Axonal connections from one axon to another generally made to what?
Dendritic spines
