Lecture 2 - Functional Neuroanatomy Flashcards
Santiago Ramon y Cajal
Used Golgi method (learned when becoming professor) and artistic ability -> Nervous system investigations Golgi and Cajal = Nobel prize in Physiology/Medicine (despite different veiws on brain structure) o Golgi = Neurons are continuous (physically touch each other -> reticular theory) o Cajal = Neurons are contiguous (small gaps between them -> Neuron theory/doctrine) Cells/neurons independent from eachother (structurally, metabolically and functionally) Information must be transmitted across these gaps
Neuron structure
Input zone (Dendrites) -> Where neurons collect/ integrate information from other cells/ neurons Integration zone (Cell body) -> Where the decision to produce a neural signal is made Conduction (Axon) -> Where information is transmitted over great distance Output zone (Axon/ Synaptic terminal) -> Where the neuron transfers information to other cells Each neuron has different function based on structure
Different size and shapes of neurones
(3 examples of 200+) o Multipolar (most common in brain) -> motor neurones (muscle control), interneurones (relay and integrate information for learning and memory) o Bipolar (common in sensory system, e.g. vision) -> o 1 dendrite + 1 axon o Unipolar (alson seen in sensory systems, e.g. touch) -> o 1 branch leaves cell body, spreads in 2 directions Information integrates just below dendrites not in cell body
Function of neuron
o Depends on how neurons are connected Depends on connection (synapse) strength Depends whether connections (synapses) are excitatory or inhibitory Can change through changes in synaptic strength (e.g. memory) Depends on information received Strengthen by learning (e.g. learning piano, starts of not effecting the next neurone much to more and more as learn better)
Cells of the nervous system
o Neurons -> main information processing cells o Glia -> support and maintenance o Techniques to visualise cells Static staining- veiw the systems (see picture for example) Fibre tracing- how neurones connect to each other
Composition of an atom
nucleus -> consisting of protons (positive charge/ 1+) and neutrons (neutral/ no charge) orbited by electrons (negative charge/ 1-) No. electrons = no. protons (negative and positive charges cancel out -> molecule has no charge) Atoms are held together by electrostatic force: o Opposite charges attract one another (electrons that orbit are held in place by attracting to the positive charge of the protons AND molecules with an overall negative charge attract other molecules with a negative charge also) o Same charges repel one another
Ion
Ions= atoms/ molecules that have lost/ gained one or more electrons Ions that have lost electrons are positively charged (cations) Ions that have gained electrons are negatively charged (anions)
Ions in water
Solid substances made of ions are known as salts (always contain equal numbers of positive and negative charges- NaCl is the chemical formula of table salt: Na= sodium and is positive charged, Cl = Chloride and is negative charged -> hence the charges cancel each other’s charges -> making table salt have no charge) When salts are dissolved in water, positive and negative ions separate and move about freely Ions are still influenced by electrostatic forces
Positive ions
Cations Sodium (Na+): generating action potentials, mainly outside neuron (extracellular) Potassium (K+): maintaining resting potential, mainly inside neuron (intracellular) Calcium (Ca2+): synaptic transmission, almost exclusively outside neuron (extracellular)
Negative ions
Anions Chloride ions (Cl-): suppressing action potentials, mainly outside neuron (extracellular) Proteins (An-): maintaining resting potential, mainly inside neuron (intracellular)
Glial cells
Astrocytes Star shaped Each astrocyte can connect with up to 100,000 neurons Neurones stayed same with evolution, but astrocytes have become much more complex Regulate blood flow to active neurons -> ensures oxygen for energy needed for neurons to process and remain alive Create scar tissue stopping spread of damage to neighbouring tissue -> Forming and modulating neural connections during development -> Microglia Very small Travels to injured sites in the brain to remove debris that could damage brain -> immune system, Works less as get older -> disfunction results in Alzheimer’s Oligodendrocytes Myelination (creating the layer of fat around the axon -> speed up neural transmission) Brain and spinal cord Schwann cells Myelination (creating the layer of fat around the axon -> speed up neural transmission) Rest of the body
Demylinating disease
Multiple Sclerosis (MS) and Guillain Barre Syndrome (GBS) Immune system attacks the myelin produced by oligodendrocytes (MS) and Schwann cells (GBS) Probably an autoimmune disease Causes inflammation of the CNS nerves Affects insulating layer of axons -> slows/ dissolves action potential
Grey matter, white matter and basics of brain
Grey matter = neuron cell bodies White matter = neuron axons Brain floats in cerebrospinal fluid (CSF) for protection and nutrition
Orientation of the brain
Humans = bipodal -> body up, face foward
Dog - quadripudal -> body parallel to ground, face foward
Disections of brain
