Lectures 1+2 Flashcards
The study of cells of the nervous system and the organization of these cells into functional circuits that process information and mediate behavior.
neurobiology
cell in the CNS responsible for myelination, speed axonal conduction, axonal support
oligodendrocyte
cell in the CNS responsible for brain support, regulate and support synaptic transmission
astrocyte
immune cells of the CNS; function as brain macrophages to clean up dead cells and cellular debris after apoptosis
microglia
the theory that neurons are the basic structural and functional unit of the nervous system (Santiago Ramon y Cajal)
neuron doctrine
the theory that the brain is an unbroken network, a seamless, continuous web (i.e., reticulum) through which nerve impulses can travel in any direction (Golgi)
reticular theory
the process by which nerve cells receive information on their cell bodies and dendrites and conduct information to distant locations through axons
dynamic polarization
makesynapseswith
other neurons’ axons, contain neurotransmitter
receptors
dendrites
receptive sites on dendrites
spines
What are the most important organelles in a neuron and why?
- mitochondria: neurons use a lot of energy
- ribosomes (protein synthesis): more than most cells because necessary to make proteins for axon too (sometimes huge volume)
axon origin
axon hillock
axon branches
axon collaterals
The fatter the axon,the ___ the electrical conduction
faster
neuron that has two extensions
bipolar
neuron that has one extension
unipolar
neuron that has multiple extensions
multipolar
neuron that sends information to the CNS (sensory neuron)
afferent
neurons that sends information to the body (motor neuron)
efferent
Name 4 things that make neurons unique.
- most are post-mitotic (i.e., non- replicating)
- compartmentalization of structure and function
- excitable cells: can be stimulated to create an electrical current
- rapidly transmit signals over long distances
Functions of glia
- maintain ionic balances
- insulate axons and modulate rate of signal propagation
source of almost all brain tumors
glia (divides throughout life)
Structure of glia
- smaller than neurons
- outnumber neurons 10:1
- make up 1/2 of CNS volume
Which glial cell is embryologically unrelated to other glial cells? Why?
microglia - derived from macrophages outside the nervous system; migrate into the nervous system during development
Functions of astrocytes (7)
- guidance of neurons and synapse formation during development
- produce molecules necessary for neural growth (e.g., BDNF)
- provide structural support for neurons
- regulate extracellular ion and neurotransmitter concentrations after synaptic activity (via uptake pumps, gap junctions for spatial buffering)
- participate in the formation of the blood-brain barrier (astrocytic endfeet interact with capillaries)
- function in glucose metabolism
- propagate calcium signals (role in memory)
Function of myelinating cells
generate and maintain myelin sheaths around axons to provide insulation (prevent leakage of current)
Myelinating cells of the CNS
Oligodendrocytes (one myelinates multiple axons)
Myelinating cells of the PNS
Schwann cells (one myelinates only one axon)
segmented structure composed of lipoprotein
myelin sheath
gaps in myelin along the axon at which ions are exchanged across the membrane
nodes of ranvier
back
dorsal
stomach
ventral
middle
medial
side
lateral
head
rostral/anterior
tail
caudal/posterior
outermost layer of the meninges; tough, thick, flexible
dura mater
middle layer of the meninges; delicate, flexible cushioning
arachnoid mater
innermost layer of the meninges, sticks to brain surface; thin and delicate
pia mater
space between arachnoid mater and dura mater
subdural space
space between arachnoid mater and pia mater; contains collagen/elastin fiber network that’s “spider web- like”
subarachnoid space
Which space contains the CSF?
subarachnoid space
elevated ridges “winding” around the brain
gyri
small grooves dividing gyri
sulci
deep grooves, general dividing large brain regions
fissures
divides the 2 hemispheres
longitudinal fissure
divides frontal lobe from parietal lobe
central sulcus
separates cerebrum from cerebellum
transverse fissure
divides temporal lobe from frontal and parietal lobes
sylvian/lateral fissure
How can you determine the function of brain areas? (5)
-lesion studies: what happens after area is damaged or lost?
-direct brain stimulation: what does the area do?
-fMRI or PET scanning: what areas are activated
if the person performs a task?
-recording from neurons with a microelectrode: what stimulus do neurons respond to?
-multi-unit recording: record from hundreds or thousands of neurons at a time
Roles of the frontal lobe
memory formation, emotions, decision
making/reasoning, personality
involved in controlling body movements (frontal lobe)
primary motor cortex
controls facial neurons, speech, and language comprehension (left hemisphere frontal lobe only)
Broca’s area
involved in decision making (frontal lobe)
orbitofrontal cortex
controls sense of smell
olfactory bulb
cannot produce speech (but can still comprehend)
Broca’s aphasia
Roles of parietal lobe
sensing and integrating
sensation(s), spatial awareness and perception, propioception (awareness of body/body parts in space and in relation to each other)
involved in processing tactile and propioceptive information (parietal lobe)
primary somatosensory cortex
processes sensations relative to body position and orientation in space (parietal lobe)
somatosensory association cortex
processes sense of taste (parietal lobe)
primary gustatory cortex
Role of occipital lobe
primary function is the processing, integration, interpretation, etc. of visual stimuli
primary area responsible for sight; recognition of size, color, light, motion, dimensions, etc. (occipital lobe)
primary visual cortex
interprets information acquired through the primary visual cortex (occipital lobe)
visual association area
Roles of the temporal lobe
hearing, language comprehension, information retrieval (i.e., memory and memory formation)
region responsible for hearing (temporal lobe)
primary auditory cortex
region that interprets smells coming from olfactory bulb (temporal lobe)
primary olfactory cortex
responsible for language comprehension (left temporal lobe only)
Wernicke’s area
cannot comprehend language; words and sentences not clearly understood; sentence formation may be inhibited or non-sensical
Wernicke’s aphasia
part(s) of the brain responsible for respiration, circulation, posture – “maintenance” functions
medulla and pons
part(s) of the brain responsible for muscle and reflex coordination
cerebellum
part(s) of the brain containing the auditory and visual centers
midbrain
part(s) of the brain responsible for unconscious drives (e.g., hunger, thirst, sex, temperature control)
hypothalamus
part(s) of the brain that releases hormones on command from hypothalamus
pituitary
part(s) of the brain responsible for sensory and motor relays and gateways to cortex
thalamus
part(s) of the brain responsible for initiation and execution of movement
basal ganglia
part(s) of the brain responsible for vision
retina
part(s) of the brain responsible for memory
hippocampus
contains neuronal (and glial) cell bodies
grey matter
contains axons and myelin
white matter
What is simple diffusion?
- moves down [ ] gradient (i.e., from area of high concentration to low concentration)
- no energy required
- no transport protein
- restricted to nonpolar molecules (water, gases)
What is facilitated diffusion?
- moves down [ ] gradient (i.e., from area of high concentration to low concentration)
- no energy required
- requires a transport protein
- restricted to polar molecules (e.g., charged polar molecules, ions)
What is active transport?
- moves against [ ] gradient (i.e., from area of low concentration to high concentration)
- requires a transport protein
- requires an input of energy
- energy comes from ATP hydrolysis or coupling
transport proteins that carry ions or water down a concentration
gradient
channels
carrier transport proteins that carry ions or molecules with the concentration gradient; can be coupled (one with [ ] gradient and one against)
transporters
carrier transport proteins that use ATP hydrolysis as energy source; movement of ions or molecules against a [ ] gradient
ATP-powered pumps
What are the differences between carriers and channels?
channels: less specific, higher rates, non-saturable
carriers: bind with specificity, rates below limit of diffusion, saturable
How is selectivity of an ion channel conferred?
-lining of the pore; if cations pass through, pore is generally lined with – charged amino acid groups
- hydrated shell of water molecules; water molecules stick to ions in solution; some ions shed this shell, others enter a pore that
can accommodate
What 3 factors affect ionic movement?
permeability, diffusion, electrical field
Neurons are mostly ___ to anions at rest, but have many ___ channels.
impermeable; cation
What is the chemical driving force of equilibrium?
ratio of concentrations on each side of the membrane (i.e., concentration gradient)
What is the electrical driving force of equilibrium?
difference in electrical potential across the membrane
current due to concentration gradient is exactly counterbalanced by the current due to the electrical gradient across the membrane
electrochemical equilibrium
What is the general distribution of ions across the neuron?
- [K+] is 20x higher inside
- [Na+] is 10x higher outside
- [Cl-] is 5x higher outside
- [Ca2+] is 1000x higher outside
What are the three main factors in setting the resting potential?
- absolute concentration
- concentration gradient of each ion (i.e., ratio)
- relative permeability of the membrane to each ion (i.e., how easily does each ion cross the membrane)
Membrane is more permeable to __ than any other ion
because of open __ channels at rest.
K+
What happens at Vrest to Na+ and K+?
• Na+ follows its concentration and electrical gradients
into the cell
• K+ follows its concentration and electrical gradients out
of the cell
What is the Na+/K+ transporter and how does it work?
antiporter: two K+ into the cell, three Na+ out of the cell
maintains the concentration gradient AND makes the inside of the cell more negative
Na+/K+ ATPase transporter
70% of all energy consumption in the brain is used to
_____.
pump Na+ out and K+ back into neurons
What sets the resting membrane potential?
Na+/K+ ATPase transporter and leaky channels
