List #7 Flashcards
myelin
-lipid material that forms a sheath like covering around some axons
axonal transport
- movement occurs in both directions between the cell body and the ends of the axon.
- enzymes required for neurotransmitter synthesis are produced in the cell body and transported to the axon terminals.
membrane potential
- The potential difference across the cell membrane(measured in millivolts)
resting membrane potential
- one that is not sending impulses or responding to other neurons(-70 millivolts)
action potential
- a rapid change in the membrane potential, first in a positive direction, then in a negative direction, returning to the resting potential
- all or nothing
- regenerative
depolarization
- if the membrane becomes more positive than the resting potential
- can be caused by Sodium entering
- means the threshold is lowered for an action potential
hyperpolarization
- if the membrane potential becomes more negative than the resting potential
- the threshold is raised
refractory period
- During the absolute refractory period which lasts about 1/1,000 of a second, the axon’s voltage-gated sodium channels are temporarily not responsive at all, and the axon cannot be stimulated.
- Then the relative refractory period follows, as the membrane reestablishes its resting potential.
saltatory conduction
- Action potentials appear to jump form node to node
- conduction on myelinated axons is many times faster than conduction on unmyelinated axons
synaptic potentials
- enable one neuron the affect another
- EPSP/IPSP
- graded
- non-regenerative
EPSP
- A neuro transmitter binds to a post-synaptic receptor and opens sodium ion channels, the ions diffuse inward, depolarizing the membrane possibly triggering an action potential.
- lasts for about 15 milliseconds
- Depolarizing
- Glumate
IPSP
- A different neurotransmitter binds other receptors and increases membrane permeability to potassium ions, these ions diffuse outward hyperpolarizing the membrane
- Hyperpolarizing
- GABA
monoamines
- modified amino acids
neuropeptides
- These peptides act as neurotransmitters or a neuromodulators, which are substances that alter a neurons response to a neurotransmitter or block the release of a neurotransmitter.
- enkephalins and endorphins
enkephalins
-Generally inhibitory; reduce pain by inhibiting substance P release (CNS)
glutamic acid (glutamate)
-Generally excitatory (CNS)
monoamine oxidase
- Inactivates the monoamine neurotransmitters epinephrine and norepinephrine after reuptake
- It is found in the mitochondria in the synaptic knob
serotonin
-Primarily inhibitory; leads to sleepiness; action is blocked by LSD, enhanced by selective serotonin reuptake inhibitor antidepressant drugs (CNS)
tryptophan
- Neurotransmitter affected: Serotonin
- Mechanism of Action: Stimulates neurotransmitter synthesis
- Effect: sleepiness
dopamine
- Creates a sense of well-being; deficiency in some brain areas associated with Parkinson disease (CNS)
GABA
- Generally inhibitory (CNS)
endorphins
-Any group of neuropeptides synthesized in the pituitary gland and hypothalamus that suppress pain
meninges
- located between the bone and the soft tissues of the nervous system
- They have three layers the dura mater, arachnoid mater, and the pia mater
spinal nerves
-Nerves that arise from the spinal cord
reflex arc
- Components of a reflex, consisting of a sensory receptor, sensory neuron, interneuron, motor neuron, and effector
- protection
patellar knee jerk reflex
- example of a simple monosynaptic reflex, so-called because it uses only two neurons- a sensory neuron communicating directly to a motor neuron.
ascending and descending tracts of the spinal cord
- ascending tracts of the spinal cord are afferent information dealing with sensory neurons
- descending tracts of the spinal cord deal with efferent information and motor neurons
central nervous system
-Consists of the brain and spinal cord.
peripheral nervous system
-Consists of cranial and spinal nerves
sensory receptors
- The ends of neurons in the peripheral nervous system provide the sensory function of the nervous system.
- These receptors gather information by detecting changes inside and outside of the body.
autonomic nervous system
-Communicates instructions from the CNS that control viscera, and thus causes involuntary subconscious actions; heart and various glands
sympathetic division
- That part of the autonomic nervous system that arises from the thoracic and lumbar regions of the spinal cord
- “fight or flight”
parasympathetic division
- Part of the autonomic nervous system that arises from the brain and sacral region of the spinal cord
- “rest and digest”
interneurons
- they lie within the brain or spinal cord
- relay information from one part of the brain or spinal cord to another.
projecting neurons
-Broadly defined, projection neurons are neurons whose axons extend from the neuronal cell body within the central nervous system (CNS) to one or more distant regions of the CNS.
cerebral hemispheres
- essentially mirror images of each other
olfactory bulbs
-extensions of the cerebral cortex just beneath the frontal lobes
optic chiasm
- X-shaped structure on the underside of the brain formed by optic nerve fibers that cross over
hypothalamus
- Part of the brain located below the thalamus and forming the floor of the third ventricle
- ANS: controlling our emotional state
pituitary gland
- Endocrine gland attached to the base of the brain that consists of anterior and posterior lobes; the hypophysis
midbrain
- Small region of the brainstem between the diencephalon and the pons
pons
- Part of the brainstem above the medulla oblongata and below the midbrain
cerebellum
- communicates with other parts of the CNS by tracts; integrates sensory information concerning the position of body parts; coordinates muscle activities and maintains posture
medulla oblongata
- Part of the brainstem between the pons and the spinal cord
tentorium cerebelli
- separates the occipital lobes of the cerebrum from the cerebellum
Somatic nervous system
- communicates voluntary instructions originating in the CNS to skeletal muscles, causing contractions.
