Nervous System Flashcards
there are varying levels of ___________ of nervous systems; higher __________ ability = more _______ behavior
there are varying levels of complexity of nervous systems: higher cognitive ability = more complex behavior
sensory neurons
transmit information from receptors that detect external (ie light, heat, sound) and internal (ie blood CO2 level, muscle tension) to the CNS
interneurons
integrate (analyze and interpret) sensory input in the CNS
motor neurons
transports motor output out of the CNS to effector cells (ie muscle and endocrine cells)
reflex
the body’s automatic response to stimuli that allow for a rapid response to stimuli- can be either spinal or cranial reflexes (ie knee-jerk, pupil dilation)
difference of reflexes from other information processing
decreases the number of neurons involved to increase speed of action potential to minimize bodily damage
-limited need for cognitive integration - involuntary
dendrites
receive signals from sensor cells
cell body
contains main organelles and nucleus
axon hillock
the region where the action potential is generated
axon
transmits the signal (action potential) to other cells
myelin sheath
insulating cells surrounding the axon
formed by: Oligodendrocytes in CNS and Schwann Cells in the PNS
synaptic (axon) terminal
the site where neurotransmitters are released into the synapse to communicate with other cells
synapse/synaptic cleft
gap between two neurons where communication through neurotransmitters occurs
types of supporting cells
astrocytes, glial cells, oligodendrocytes/Schwann cells
astrocytes
regulate the concentration of ions and neurotransmitters and forms the blood-brain barrier in the CNS
glial cells
lay the foundation for the development neural tube in fetuses and are responsible for structural support and the proper functioning of neurons in the CNS
Oligodendrocytes
form the myelin sheath in the CNS
Schwann Cells
form the myelin sheath in the PNS
resting potential
- 70mV
- results from differences in ionic concentration between the inside and outside of the cell
- higher concentration of Na+ on the outside
- higher concentration of K+ on the inside
how is resting potential maintained?
sodium-potassium pumps use active transport to pump 3 Na+ ions out for every 2 K+ ions pumped in and maintain negative potential inside and positive potential outside of the cell
action potential in role of membrane potential
Neurons have changes in membrane potential in response to stimuli that result
in either:
- hyperpolarization: inside of membrane becomes more negative
- depolarization: inside of membrane becomes more positive
graded potentials
change in membrane potential that varies depending on strength of the stimulus
action potentials are stimulated at _____ _________ and move toward ________ _________
axon hillock
synaptic (axon) terminals
conduction of action potentials
strong depolarization in one area spreads through electrical current
factors that affect conduction speed:
axon diameter, myelin sheath, saltatory conduction along nodes of Ranvier
synaptic communication
- The arrival of an action potential at the axon/synaptic terminal opens calcium voltage gated ion channels, which allows calcium ions to diffuse into the cell.
- The diffusion of calcium into the cell causes vesicles to fuse and release neurotransmitters into the synapse via exocytosis.
- The neurotransmitters bind to ligand gated protein channels on the postsynaptic cell.
- Neurotransmitters are degraded by enzymes, recycled, or reuptaked.
EPSP
excitatory post-synaptic potential causes depolarization (+) that moves the membrane potential toward threshold opens Na+ channels to flow in
IPSP
inhibitory post-synaptic potential causes hyperpolarization (-) that moves the membrane potential away from threshold opens K+ channels to flow out
Neurotransmitters
acetylcholine, biogenic amines, endorphins
acetylcholine
excitatory; found in neuromuscular joints and released by motor neurons to signal muscle contraction
biogenic amines
epinephrine, norepinephrine, dopamine, seratonin
epinephrine
excitatory, fight or flight response (adrenaline)
norepinephrine
excitatory in the autonomic nervous system
dopmine
reward pathways in the CNS
seratonin
feelings of happiness in the CNS
endorphins
neuropeptides- naturally decrease pain perception and released during exercise
the _________ of the stimulus determines the _________ at which action potentials are sent
strength; frequency
Central Nervous Stystem
brain and spinal cord
-integration center for complex behaviors
Peripheral Nervous system
consists of cranial and spinal nerves along with associated ganglia
-transmits information to and from the CNS
PNS is divided into __________ Nervous System and the __________ Nervous System
somatic and autonomic
somatic nervous system
voluntary system bc it is under conscious control to move skeletal muscles in response to external stimuli
autonomic nervous system
involuntary system bc it regualtes internal conditions by contracting smooth (digestive) and cardiac (heart) muscles
autonomic nervous system is divided into _____________ and _______-____________ regions
sypathetic and para-sympathetic
sympathetic nervous system
fight or flight response
*sympathizes with the fact that you are about to die
parasympathetic nervous system
rest and digest
restores bodily functions to resting state after heightened stress
Brainstem
evolutionaryily, oldest part of the brain (primitive)
controls homeostatic functions (ie breathing, heart function, digestion) and some coordination
Cerebellum
Controls learning & memory of motor functions
through integration of sensory & motor
information (i.e. hand-eye coordination)
Cerebrum
Higher functioning brain
- Controls thought & action
- Divided into lobes for varying functions
Summation
Individual post-synaptic potentials combine to make larger
changes to membrane potential
Temporal Summation
one potential directly after the other
Spatial Summation
multiple presynaptic neurons working simultaneously on
the one postsynaptic neuron
Action Potential Steps
- Resting Potential
- Depolarization (Rising Phase)
- Repolarization (Falling Phase)
- Hyperpolarization (Undershoot)
Resting Potential
gated Na+ and K+ channels are closed,
while ungated channels are open to maintain resting
potential
- no movement of Na+ and K+ ions
Depolarization
stimulus depolarizes membrane opening some
gated Na+ channels & allowing a small increase in Na+
- once threshold of -55 mV is reached, most gated Na+ channels will open, allowing Na+ ions to diffuse into the cell, allowing inside of membrane to become positive
- no movement of K+ ions
Repolarization
at +35 mV, Na+ voltage-gated channels close and lock while K+ channels open to allow K+ ions to diffuse out of the cell, restoring the negative chanrge
- no movement of Na+ ions
Hyperpolarization
- K+ gated channels remain open and allow K+ ions to diffuse out of the cell until -80mV
- after -80mV, K+ gated channels close and the Na+/K+ pump restores resting potential
