WEEK 2 - Neurons and the brain Flashcards
what are the meninges?
the protective sheaths around the brain and the spinal cord
what are the 3 layers of the meninges
Dura mater, arachnoid membrain, pia matter
what is the gap between the pia matter and the arachnoid membrane?
subarachnoid space
what is the subarachnoid space filled with?
CSF
what is CSF
cerebral spinal fluid
what is the white matter in the brain?
milenated axon fibres
what is the grey matter in the brain?
neurons of the brain and other cells
what is the limbic love?
where we would have parts of the amygdala and hippocampus (located in the middle of the brain)
what is the substance that fills the series of chambers inside the brain?
CSF - cerebrospinal fluid
what are the chambers in the brain that are filled with CSF known as?
the ventricular system
what are the two mian functions of the CSF?
mechanical shock absorber - since it is floating in CSF, the brain is protected from sudden movements that would otherwise cause contact with the inside of the skull
medium for exchange materials including nutrients between blood vessels and brain tissue
what is the function of the cerebral cortex?
provides for flexible control of patterns of movement
permits subtle discrimination among complex sensory patterns
makes language and symbolic thinking possible
what is the functional organization of the cortex?
primary areas and association areas
what are the major divisions of the cerebral cortex?
frontal lobe, Broca’s area, motor cortex, central fissure, somatosensory cortex, parietal lobe, occipital lobe, Wemicke’s area, temporal lobe
frontal lobe is for…
abstract thinking, planning, social skils
Broca’s area
speech production, grammar
parietal lobe
touch, spatial orientation, nonverbal thinking
occipital lobe
vision
Wemicke’s area
speech comprehension
temporal lobe
language, hearing, visual pattern recognition
what are the major subcortal divisions of the brain?
cerebral cortex, amygdala, hypothalamus, midbrain, brainstem, reticular formation, spinal cord, medulla, pons, cerebellum, thalamus, corpus collosum, forebrain
cerebral cortex
thin outer layer responsible for most complex behaviour and higher mental processes
amygcala
part og limbic system, involved in aggression and fear
hypothalamus
responsible for regulating emotions and drives (e.g. hunger, thirst, sec, aggression)
mid brain
helps coordinate movement patterns, sleep and arousal
brainstem
helps regulate reflex activities critical for survival (e.g. heartbeat and respration)
reticular formation
helps screen incoming sensory information and controls arousal
spinal cord
responsible for transmitting informaito between the brain and the rest of the body handles simple reflexes)
medulla
Responsible for breathing heartbeat and other vital life functions
cerebellum
coordinates fine muscle movement, balance ad some percepttion and cognition
Pons
involved with resporation movement, waking sleep and dreaming
thalamus
relays sensory messages to cortex
corpus callosum
thick band of axons connecting the two hemispheres of the cerebral cortex
what is the function of the spinal cord
to distribute motor connection to the muscles and glands and to collect somatosensory information
what is the spinal cord protected by?
vertebral column
where does the spinal cord pass through?
a hole in each of the vertebrae
how long is hte spinal cord?
two thirds of the length of the vertebral column
what is the rest of the space in the spinal cord filled with?
mass of spinal nerves composing the cauda equina
what order does the subdivisions of hte spinal cord go in from the brain?
Cervical Thoracic Lumbar Sacral Coccygeal
what is sensation
the process by which the body gathers information about the environment and transmits the information to the brain for initial processing
what is perception?
an active process by which the brain selects, organises and interprets sensory information
what are neurons?
the basic functional unit of the nervous system, they take in information from other neirons (reception), integrate those signals (condiction) and pass signals to other neirons (transmission)
Glial cells
nourish, protect, and physically support neurons and are thought to be particularly critical in brain development. One type of glial cell, the oligodendrocyte, covers the axons of neurons with myelin, a substance critical to the effective functioning of the brain.
what are the parts of the neuron?
dendrites, soma, acon, terminal buttons, myelin
dendrites
function principally to receive messages from other neurons. They transmit the information they receive to the soma.
Soma
(cell body) contains mechanisms that control the metabolism and maintenance of the cell. It also collates ‘messages’ from other neurons.
The Axon
carries ‘messages’ away from the soma towards the cells with which the neuron communicates; these messages are called action potentials
Terminal bytton
are located at the end of the ‘twigs’ that branch off the ends of axons; they secrete neurotransmitters which affect the activity of other cells with which the neuron communicates
Myelin
insulates some axons to promote efficient transmission of the action potential. It serves to increase the speed of propagation of the action potential along the axon
what is the spine important for?
important for learning and memory and is likely to be involved in psychopathologies
what is the cell membrane made up of?
lipid bilayer
what is a lipid bilayer?
two layers of fatty molecules - within which may types of specialised proteins ‘float’
embedded protein molecules
protein form pores or channels that control movement of material into and out of cell
What does the cell membrane do?
separates two different chemical solutions
these solutions interact via pores or channels (typically these are protein molecules with a central passage)
what happens when the cell membrane is at rest
the pores are usually closed to precent interchange of inside (intracellular) and outside (extracellular) materials
there are more sodium ions (Na+) outside the cell than inside. and there are more potassium ions (K+) inside the cell than outside
What is the resting potential of the neuron?
-70mV
what is the resting membrane potential (RMP)?
derives from the difference in chemical composition inside and outside the cell at rest. It is the result of relative concentrations of potassiium ions, chloride ions and negatively charged protein ions and sodium ions
what is action potential
a brief reversal in the resting charge of the neuron
what triggers an action potential?
an exchange of ions across the neuron membrane
how is an action potential created?
when the neuron membrane is sufficiently depolarised (i.e. the resting potential moves towards 0mV). when the depolarisation reaches the threshold of about -55mV, then neuron will fire an action potential. if the neuron does not reach the critical threshold level, there is no action potential fire
what is the all or non principle?
If the threshold level is reached, an action potential of a fixed sized will always fire. For any given neuron, the size of the action potential is always the same.
Therefore, the neuron either does not reach the threshold or a full action potential is fired
what is the process of movement of sodium potassium ions during the action potential?
- sodium channels open; sodium ions enter, reversing membrane potential
- potassium channels open; potassium ions leave, restring membrane potential
- Ion transporters pump sodium and potassium ions back to their original locations
how is the sped of propagation of the Action potential determined?
diameter of the acon, presence or absence of a myelin sheath
what is the myelin sheath
an electric insulator that prevents current flow across membrane. the currents can only flow at breaks in the membrane
what is synaptic transmission?
the space between neurons. When an action potential reaches the terminal buttons it caused the release of specialised chemicals called neuro transmitters that travel across the synaptic cleft and are received by the dendrites of other neurons
what is the first step to the releasr of neurotransmitters from a terminal button?
before the action potential has arrived, the neurotransmitters are stored in vesicles within the terminal button
what is the second stage of neurotransmitters from a terminal button?
the action potential triggers the release of the neurotransmitter into the synaptic cleft
what is the third stage of neurotransmitters from a terminal button
The neurotransmitters diffuse across the synaptic cleft. Some of them will attach to receptor molecules in the postsynaptic membrane and activate them, thus either inhibiting or enabling the postsynaptic neuron to generate an action potential.
what are the steps to neurotransmitter action?
- neurotransmitter are synthesized from chemical building blocks called precursors
- neutrotransmitters are stored in vesicles
- ction potentials cause vesicles to fuse to the presynaptic membrane and release their contents into the synapse
- released neutransmitters bind to the postsynaptic receptors
- neurotransmission is terminated by reuptake, enzyme deactivation, or autoreception
