Introduction to Neuroscience Flashcards
Name the major divisions of the nervous system and what they include
Central nervous system:
- brain
- spinal cord
Peripheral nervous system:
- Autonomic nervous system - involuntary, internal organs, blood vessels, glands
- Somatic nervous system - voluntary, skin, joints, muscles
What is in the forebrain?
- Cerebral hemispheres
- cerebral cortex: controls voluntary movement and contains 4 lobes (frontal, temporal, occipital, parietal)
- basal nuclei: fine tunes motor behaviour
- Thalamus: relays motor and sensory input to cerebral cortex, regulates consciousness, sleep and alertness
- hypothalamus: maintains homeostasis
what does the midbrain do?
- controls basic movement
- contains the tectum, the cerebral aqueduct, tegmentum, and the cerebral peduncles.
what does the hindbrain do and contain?
- pons: controls respiratory and breathing patetrn
- medulla: controls respiration and heart beat
- cerebellum: controls motor coordination and balance
What does the brainstem?
- regulates the body’s autonomic functions
- connects the brain to the spinal cord
what is the association cortex?
- integrates information from different sensory systems
what is the corpus callosum?
- white matter area
- carries info between two hemispheres
what is diencephalon?
- thalamus
- hypothalamus
Structure of the ventricular system
2 lateral ventricles
these form the 3rd ventricle at the hypothalamus
a cerebral aquiduct forms the 4th ventricle near pons and medulla
cavity filled with cerebrospinal fluid
what does cerebrospinal fluid do?
- maintains ion levels
- removes waste products
- provide physical barrier by making brain more buoyant
What are the subdivisions of the spinal cord (rostral to caudal)?
- Cervical,
- cervical enlargement (control upper limbs),
- thoracic,
- lumbar,
- lumbosacral enlargement (control lower limbs),
- sacral
what makes up the nervous tissue?
Grey matter:
- cell bodies of neurons and glia, neuronal cell bodies and dendrites, cerebral cortex, nuclei and spinal cord in centre
White matter:
- neuronal axons wrapped in myelin, outside of spinal cord via tracts which carry different info, forebrain
What are the functional divisions of the spinal cord?
Dorsal = where sensory info is processed afferent = sensory neuron entering dorsally (peripheral to central) Ventral = where motor info is sent out (anterior part) Efferent = motor neuron leaving ventrally (central to peripheral)
Nucleus = cluser of cell bodies in CNS Ganglion = cluster of cell bodies in PNS
what cell types make up neural circuits?
Neurons:
- excitable cells that conduct impulses
- integrate and relay info within a neural circuit
Glia:
- supporting cells which keep neurons healthy and influence neuronal output
- maintain homeostasis, protection and assist neural function
there are 85 billion of each cell type
Structures of neurons
Soma/cell body:
- contains nucleus, nucleolus, ribosomes, RER, golgi apparatus, mitochondria (produce lots of ATP to maintain ion gradients for APs)
Axons:
- axon hillock - attaches to soma
- axon initial segment - where APs are first generated and have different no. ion channels depending on type of neuron
- axon collaterals - branches diverging from axon to innervate other cells
- axon terminal/bouton
Dendrites:
- branches form dendritic trees (arbours) which can converge onto one neuron (lots of integration)
- dendritic spines increase SA of dendrite and are plastic (inactive spines are taken up, active dendrites produce more spines)
what is fast axoplasmic transport?
signals travel 1000mm per day
move along microtubules, with kinesin and dynein moving molecules using ATP
- anterograde transport by kinesin down the cell
- retrograde transport by dynein up the cell
what is a pseudounipolar neuron?
- example = dorsal root ganglion (afferent neuron)
- one neurite coming off the cell body splits into 2
- one end of the split will become presynaptic terminal
- the other end will become a dendritic tree
- there is a small area for receiving synaptic input, making it highly specific
- peripheral process and central process are both axons
what is a bipolar neuron?
- example = retinal bipolar cells
- has 2 neurites branching off from the soma
- one arm is axonic, the other arm is dendritic
- small area for receiving synaptic input = highly specific
what is a multipolar neuron?
- example = purkinje cells in the brain
- receives around 150,000 contacts
- large area for receiving synaptic
input = integrates lots of info
- large area for receiving synaptic
- high levels of convergence (lots of input into a single neuron)
describe the two types of dendritic geometry:
Pyramidal:
- distinct apical and basal dendritic trees
- basal comes from cell bodies and processes info from multiple neurons to apical arms
- pyramidal shaped soma
- example = seen in layers of neocortex or hippocampus
stellate:
- star shaped dendritic arbour
- example = seen in neocortex
name the 3 types of neuron:
- Sensory/afferent = project from PNS to CNS
- Motor/efferent = project from CNS to PNS
- interneuron = stays within CNS and connect brain regions, short axons and process info in local circuits
What are the homeostatic, myelinating and phagocytic cells of the CNS, PNS and ENS?
CNS:
- homeostatic = astrocytes
- myelinating = oligodendrocytes
- phagocytic = microglia
PNS:
- homeostatic = satellite cells
- myelinating = schwann cells
- phagocytic = schwann cells + macrophages
ENS:
- homeostatic = enteric glia
What are astrocytes and what are their functions?
- control environment of surrounding neurons
- glycogen stores of the brain
- metabolise glycogen to supply lactate to neurons within 5 ins as a fuel to produce ATP
- endfeet take up glucose to control separation of vasculature from ECF
- forms the BBB
- buffer extracellular calcium to control excitability
what are microglia and what are their functions?
- make up 15% of the glial cells of the CNS
- phagocytic role = clear away cellular debris
- release growth factors for neuron growth and myelination
- involved in pruning = removes inactive parts of neuron
- can have harmful roles in neurodegenerative diseases
what are oligodendrocytes and what are their function?
- myelinating cells of CNS = form myelin sheaths of CNS axons
- can have 12-30 processes from cell body to myelin sheath
- insulate axons
- provide multiple segments to one axon
what are schwann cells and what are their functions?
- myelinating glial cell of the PNS = form myelin sheaths around PNS axons
- one schwann cell provides one myelin segment to a single axon
what is the formation and function of the myelin sheath?
formation:
- oligo cytoplasm wraps many times around the axon
- cytoplasm is squeezed out by compaction
- myelin sheaths maintain contact with glial cells for nourishment
function:
- insulating role
- forms nodes of ranvier for saltatory conduction
- APs can jump along to increase
conduction speed
What is the Nissl stain and what does it indicate?
Nissl stain:
- Nucleus, nucleolus, RER and ribosomes are stained to distinguish between neurons and glia
- Highlight rRNA as the basophilic dye binds to negatively charged molecules
- cannot highlight axons as they do not have ribosomes or RER
- allows observation of density and distribution of neurons - not in detail
What is the Golgi stain and what does it indicate?
Golgi stain:
- silver chromate allows small % of neurons to be observed in depth
what is immunohistochemistry and what does it indicate?
Immunohistochemistry:
- primary antibodies specifically bind to target
- secondary antibody is associated with fluorescent tag and binds to primary antibody
- when bound, secondary antibody fluoresces to show location of target cells
what is retrograde tracing and what does it indicate?
retrograde tracing:
- spinal is injected with HRP to leave HRP deposit in brain cell bodies
- 2 days later after retrograde transport, slice brain to see HRP labelled neurons
- shows map of nervous system in brain
what is GFP and what does it indicate?
GFP:
- reporter gene GFP is tagged onto promoter of gene which expresses neurotransmitter
- only neurons expressing that promoter will fluoresce
