Chapter 48-49 (Neurons and Nervous System) Flashcards
Neuron
has structure and properties that allow it to conduct signals by taking advantage of the electrical charge across its plasma membrane.
central nervous system (CNS)
where integration takes place; this includes the brain and a spinal cord. Brain is the organ of the CNS where information is processes and integrated. Spinal cord is the nerve cord of vertebrates that is continuous with the base of the brain and housed within the vertebral column
peripheral nervous system (PNS),
carries information into and out of the CNS. PNS is composed of nerves and ganglia. Nerves are the bundled axons of multiple neurons of the PNS. Nerves
channel and organize information flow through the nervous system.
Nerves
are the bundled axons of multiple neurons of the PNS
Ganglia
(singular: ganglion) are clusters (functional groups)
of nerve cell bodies in a nervous system.
Glial cells
support, nourish, regulate and augment the functions of neurons.
Embryonic radial glia
form tracks along which newly formed neurons migrate
Astrocytes
are glial cells with diverse functions including providing structural support for neurons, regulating interstitial environment, facilitating synaptic transmission and assisting in regulating the blood supply to the brain. Astrocytes also participate in the formation of the blood-brain barrier, which restricts the entry of most substances into the brain.
Radial Glia Cells
cells and astrocytes can both act as stem cells. Researchers are exploring approaches to using neural stem cells to replace brain tissue that has ceased to function normally
The Brain and Spinal Cord Consist of
Grey matter and White matter
Grey Matter
which consists of neuron cell bodies, dendrites, and
unmyelinated axons
White Matter
which consists of bundles of myelinated axons
forebrain
has activities including processing of olfactory input, regulation of sleep, learning, and any complex processing
Midbrain
coordinates routing of sensory input
Hindbrain
controls involuntary activities and coordinates motor activities
Frontal Lobe
Contains: Prefrontal cortex which functions decision making, planning. Motor cortex functions control of skeletal muscles. Broca’s area functions forming speech
Pariental Lobe
Contains: Somatosensory cortex (sense of touch) and Sensory association cortex (integration of sensory information)
Temporal Lobe
Contains: Auditory cortex (hearing) and Wernicke’s area
comprehending language
Occipital Lobe
Contains: Visual cortex (processing
visual stimuli and pattern recognition) and Visual association cortex (combining images and object recognition)
Cerebral Cortex
controls voluntary movement and cognitive functions
cerebrum
largest structure in the human brain, is essential for language, cognition, memory, consciousness, and awareness of our surroundings
Somatosensory receptors
provide information about touch, pain, pressure, temperature, and the position of muscles and limbs
Thalamus
directs different types of input to distinct locations
motor system
carries signals to skeletal muscles and can be voluntary
autonomic nervous system
regulates smooth and cardiac muscles and
is generally involuntary. Has sympathetic and parasympathetic division
enteric nervous system
exerts direct control over the digestive tract, pancreas, and gallbladder
sympathetic division
regulates arousal and energy generation (“fight-
or-flight”response)
parasympathetic division
has antagonistic effects on target organs and promotes calming and a return to “rest-and digest”functions
Functional MRI (fMRI)
Functional magnetic resonance imaging, or fMRI, is
a technique for measuring brain activity. It works
by detecting the changes in blood oxygenation and
flow that occur in response to neural activity –when a brain area is more active it consumes more oxygen and to meet this increased demand blood flow increases to the active area. fMRI can be used to produce activation maps showing which parts of the brain are involved in a particular mental process.
As a brain imaging technique FMRI has several
significant advantages:
- It is non-invasive and doesn’t involve radiation,
making it safe for the subject. - It has excellent spatial and good temporal
resolution. - It is easy for the experimenter to use.
Brain Language Centers
Broca’s area is important for speech. Wernicke’s area is
important for language comprehension.
Positron-emission tomography (PET)
enables a display of metabolic activity through injection of radioactive glucose
The limbic system in the brain
The functional association of various brain centers
including the amygdala and hippocampus and
parts of thalamus.
amygdala
a mass of nuclei near the base of the cerebrum that is most important for the storage of emotion
Where do new neurons form
Hippocampus
synapse
junction between an axon and another cell. The synaptic terminal of one axon passes information across the synapse in the form of chemical messengers called neurotransmitters
Neuroransmitters
synaptic terminal of one axon passes information across the synapse in the form of chemical messengers
Sensory neurons
transmit information about external stimuli such as light,
touch, or smell
Interneurons
integrate (analyze and interpret) the information
Motor Neurons
transmit signals to muscle cells, causing them to contract
Reflex
is the body’s automatic response to a stimulus
myelin sheath
which causes an action potential’s speed to increase. Myelin sheath is an insulating coat of cell membranes
made by glia— oligodendrocytes in the CNS and Schwann cells in the PNS
MEMBRANE POTENTIAL
Difference in electrical potentials
across a membrane
Resting Potential
is the membrane potential (voltage) when the axon is
not conducting an impulse
Action Potenial
is a rapid change in polarity across a portion of an
axonal membrane
action potential can be considered as a series of stages
- At resting potential: most voltage-gated sodium (Na+) channels and voltage-gated potassium (K+) channels are closed
- Voltage-gated Na+channels open first and Na+flows into the cell (depolarization)
- During the rising phase, the threshold is crossed, and the membrane potential increases
- During the falling phase, voltage-gated Na+channels become inactivated; voltage-gated K+channels open, and K+flows out of the cell
- During the undershoot, membrane permeability to K+ is at first higher than at rest, then voltage-gated K+channels close and resting potential is restored
- During the refractory period after an action potential, a second action potential cannot be initiated
4 types of Membrane Potential
- resting potential
- action potential
- voltage-gated channels
- Na-K pump
Acetylcholine
is a common neurotransmitter in vertebrates and
invertebrates, is involved in muscle stimulation, memory formation, and learning
Excitatory postsynaptic potentials (EPSPs)
are depolarizations that bring the membrane potential toward threshold
Inhibitory postsynaptic potentials (IPSPs)
are hyperpolarizations that move the membrane potential farther from threshold
Neuronal plasticity
describes the ability of the nervous system to be
modified. Changes can strengthen or weaken signaling at a synapse.
Autism
a developmental disorder, involves a disruption in activity-dependent remodeling at synapses.
Children affected with autism display impaired communication and social interaction, as well as stereotyped, repetitive behaviors
