chapter 12 nervous system Flashcards
Brain and spinal cord
Consists of nervous tissue, connective tissue, and blood vessels
Functions to process and coordinate sensory data from inside and outside body
Motor commands control activities of
peripheral organs (e.g., skeletal muscles)
Higher functions of brain include intelligence, memory, learning, and emotion
which nervous system is this one ?
CNS
Includes all nervous tissue outside CNS and ENS
Delivers sensory information to the CNS
Carries motor commands to peripheral tissues
Nerves (peripheral nerves)
Bundles of axons with connective tissues and blood vessels
Carry sensory information and motor commands
Cranial nerves connect to brain
Spinal nerves attach to spinal cord
which nervous system is this one ?
PNS
Controls subconscious actions, contractions of smooth and cardiac muscle, and glandular secretions
Sympathetic division has a stimulating effect
Parasympathetic division has a relaxing effect
which system is this one ?
ANS
Controls skeletal muscle contractions
Both voluntary and involuntary (reflexes)
which system is this one ?
SNS
100 million neurons in walls of digestive tract
As many or more than in spinal cord
Use the same neurotransmitters as the brain
Initiates and coordinates visceral reflexes locally
Without instructions from CNS
Can be influenced by ANS
which system is this one ?
Basic functional units of the nervous system
Send and receive signals
Function in communication, information processing, and control
Cell body (soma)
Large nucleus and nucleolus
Perikaryon (cytoplasm)
Mitochondria (produce energy)
RER and ribosomes (synthesize proteins)
what is the term for this ?
Neuron
Neurofilaments and neurotubules
Similar to intermediate filaments and microtubules
Neurofibrils
Bundles of neurofilaments that provide support for dendrites and axon
where does this belong?
Cytoskeleton of perikaryon
Dense areas of RER and ribosomes in perikaryon
Make nervous tissue appear gray (gray matter)
where is this located?
nissl bodies
Small
All cell processes look similar
Found in brain and special sense organs
which neuron is this ?
anaxonic
Small and rare
One dendrite and one axon
Found in special sense organs (sight, smell, hearing)
which neuron is this ?
bipolar
Axon and dendrites are fused
Cell body to one side
Most sensory neurons of PNS
which neuron is this ?
unipolar
def the nodes of ranvier
lie between internodes
Where axons may branch
Have one long axon and two or more dendrites
Common in the CNS
All motor neurons that control skeletal muscles
which neuron is this ?
multipolar
Regions of CNS with many myelinated axons
which matter?
white matter
Contains unmyelinated axons, neuron cell bodies, and dendrites
which matter?
gray matter
defn repolarization ?
When the stimulus is removed, membrane potential returns to normal
def the hyper polarization
Results from opening potassium ion channels
Positive ions move out, not into cell
Opposite effect of opening sodium ion channels
Increases the negativity of the resting potential
Characteristics of graded potentials
Membrane potential is most changed at site of stimulation;
effect decreases with distance
Effect spreads passively, due to local currents
Graded change in membrane potential may
involve depolarization or hyperpolarization
Stronger stimuli produce greater changes in membrane potential and affect a larger area
defn propagation
Moves an action potential along an axon in a series of steps
Occurs in unmyelinated axons
Affects one segment of an axon at a time
Step 1: Action potential develops at initial segment
Depolarizes membrane to +30 mV
Step 2: Local current develops
Depolarizes second segment to threshold
which propagation is this ?
continuous propagation
Myelinated
Large diameter
Transmit information to and from CNS rapidly
(120 m/sec), for example
Sensory information such as position and balance
Motor impulses to skeletal muscles
which fiber is this ?
FIber A
Myelinated
Medium diameter
Transmit information at intermediate speeds (18 m/sec)
which fiber is this ?
FIber B
Unmyelinated
Small diameter
Transmit information slowly (1 m/sec)
Example: most sensory information
which fiber is this ?
fiber C
Chemicals released by axon terminals that alter
Rate of neurotransmitter release
Or response by postsynaptic cell
Effects are long term and slow to appear
Responses involve multiple steps and intermediary compounds
Affect presynaptic membrane, postsynaptic membrane, or both
Released alone or with a neurotransmitter
what is this term ?
Neuromodulators
Small peptide chains
Synthesized and released by axon terminal
def this term ?
Neuropeptides
Bind to the same receptors as opium and morphine
Classes of opioids in CNS
Enkephalins
Endorphins
Dynorphins
defn this term ?
opioids
what are the dissolved gases in neurotransmitters
Nitric oxide (NO)
Carbon monoxide (CO)
