1210 Week 15

1210 Week 15

1. Lecture 1

   • Directions/Terms
     • rostral - towards the head
     • caudal -towards the tail
     • dorsal - towards the back
     • ventral - towards the front
     • gyri - ridges in the brain
     • sulci - valleys in the brain
   • Forebrain
     • Prosensephalon - divided into the telencephalon and diencephalon
     • diencephalon
       • thalamus - important relay nucleus from sensory modalities to the coretx
       • hypothalamus - involved in homeostasis and endocrine functions
       • pituitary gland - important for the release of hormones
       • limbic system - involved in mood and emotion
     • telencephalon
       • cerebral hemispheres, cerebral cortex, neocortex - higher functions
       • basal ganglia - part of the extrapyramidal motor system. The corpus striatum and caudate nucleus are important in motor disorders
       • more limbic system
   • Midbrain
     • Mesencephalon
     • substantia nigra - motor system - dopamine containing cells
     • superior colliculus - receives visual imputs, helps to focus eyes
     • periaqueductal grey matter - important in emotive pain pathways and fear
     • red nucleus - motor control structure
   • Hindbrain
     • Rhombencephalon - divided into the metencephalon and myelencephalon
     • brainstem
     • reticular formation - diffuse network of cells which control alertness and CV functions
     • raphe nuclei - in the midline medulla and midbrain - contains the seritonin cells which are the receptors for prozac
     • area postrema - pons and medulla - contains the chemoreceptor trigger zone
     • locus poeruleus - pons - contains the noradrenaline positive cells
   • Brain Devisions
     • Corpus Collozum - connected the 2 hemispheres
     • frontal lobe - conscious thought, damage can result in mood changes
     • parietal lobe - integrating sensory information from various senses, manipulation of objects, portions involved with visuospatial processing
     • occipital lobe - sense of sight, legions can produce hallucinations
     • temporal lobe - sense of smell and sound as well as processing of complex stimuli like faces and scenes
     • meninges
       • dura mater - thickest, most external, protects the CNS
       • arachnoid mater - lies between the other 2 maters in the subdural space, doesn't enter the sulci, below CSF
       • pia mater - internal layer, lies on the surface of the brain and enters the sulci
     • ventricular system - divided into 4 ventricles and contains CSF
     • neurons are classified by
       • number of neurites
       • dendrites
       • connections
       • axon length
       • neurotransmitter
   • Dopamine/Serotonin Pathways
     • dopamine
       • start at substantia nigra and VTA
       • lead to the frontal cortex, nucleus accumbens, hippocampus and striatum
       • functions
         • rewards
         • pleasure
         • euphoria
         • motor function fine tuning
         • compulsion
         • preseveration
     • serotonin
       • start at the raphe nucleus
       • leads to striatum, nucleus, accumbens, frontal cortex and then around the brain to the hippocampus
       • functions
         • mood
         • memory
         • processing
         • sleep
         • cognition

2. Lecture 2

   • Resting Potential
     • sits at -70mV
     • 4 factors contribute to resting potential
       • charged intracellular proteins - negatively charged ions contribute to the negative charge
       • Na+/K+ pump - 3 Na+ out for every 2 K+ in
       • K+ ions - try to move down their concentration gradient but the negative charge inside the cell attracts them
       • Na+ ions - the membrane is only slightly permeable so it doesn't effect membrane potential
   • Calculating Membrane Potential
     • conductance
       • the number of channels open is proportional to conductance
       • Ik = Gk(Vm-Ek)
         • Ik - K+ movement current
         • Gk - conductance
         • Vm - membrane potential
         • Ek - equilibrium potential of K+
       • the difference between Vm and Eion is the ionic driving force
     • Nernst equation
       • calculates Eion for a single ion across a membrane
       • 2.303RT/zFlog([A]o/[A]i)
         • R - universal gas constant (8.31J/molK)
         • T - temperature in Kelvin
         • F - faraday constant (96,500 coulumbs/mol)
         • z - valence
         • A - specific ion concentration
       • at body temperature 2.303RT/zF = 61.54 for cations and -61.54 for anions
     • Goldman-Hodgkin-Katz equation
       • develops the Nernst equation to calculate membrane potential
       • it allows all ions involved in the potential to be used to calculate an accurate membrane potential
       • 61.54 Log(PA[A]o/PA[A]i) + Log(PB[B]o/PB[B]i) + etc
         • P - permeability of said ion
         • A/B - each ion being calculated
       • the permeability has to add up to 1
   • Basic Principles
     • electrical gradients drive ions towards oppositely charged ions
     • concentration gradients drive ions from a high concentration to a low concentration
     • neurons use electricity to transmit signals by using ion flow across membranes
     • ion pumps actively move ions against their concentration gradient and can create gradients
     • ion channels allow ions to diffuse down their gradients and can have selective permeability
     • channels can be opened by voltage, chemicals, and mechanics