Exam 1 Flashcards
Necrosis
Death of brain tissue
Brain Fun Facts
2% of body weight 3lbs or 1500 grams Consumes 20% of energy 80% of tissue, 10% CSF, 10% blood 1000mL of blood per minute
Breakdown of Nervous System
Nervous System (NS)
Peripheral NS
Autonomic NS
Sympathetic NS (fight or flight)
Parasympathetic NS (relaxation)
Somatic NS
Central NS
Brain
Forebrain
Midbrain
Hindbrain
Spinal CordIntegrated Theory
Alexander Luria, father of neuropsychology, doctorate of medicine education and psychology
“To understand the brain foundations for psychological activity, one must be prepared to study both the brain and the system of activity.”
Brain is comprised of functional systems, behavior interacts with three basic functions
- Brainstem
- Sensory Unit
- Motor Unit
Central fissure roughly separates sensory (below) and motor (above)
Pluripotentiality
Any area of brain can be involved in few or many behaviors
Functional systems had “plasticity” can be retrained
Neuropsychology
The study of human behavior following damage to or dysfunction of the central nervous system.
Study of brain/behavior relationships How do behaviors, emotions, and thoughts relate to the brain? What parts of the brain? How does the brain work? What capacities do humans have?
Why study brain/behavior relationships?
- Diagnostic Purposes
- Rehabilitation Purposes
- Intellectual Curiosity
How is brain/behavior studied?
Invasive procedures Ablation Radiation, kills brain cells Noninvasive procedures Brain Imaging Neuropsychological Testing
Search for Engram
Karl Lashley search for memory, rats in maze, memory isn’t in one locations, entire cerebral function
The brain is…
An electrical and chemical unit
Imaging Techniques
CT: blood pooling
FMRI: functioning (tumor)
PET: function with in brain (dementia)
Nervous System:
Two Kinds of Cell
Neurons (where the action is, start with 100 billion, end with 1 billion)
Glial (the forgotten majority)
90% in CNS
Repair, support, protect
Six Kinds of Glial Cells
- Oligodendrocytes
Extensions wrap around axon of some neurons in CNS
Wraps multiple spots on axon, don’t help with neuron repair - Schwann Cells
Extensions wrap around axon of some neurons in the PNS
Wraps on single spot on axon, helps with neuron repair (cut off finger) - Microglia: clean debris
- Astrocytes: part of blood brain barrier
- Ependymal Cells: line ventricles
- Satellite Cells: muscle repair
Multiple Sclerosis
In multiple sclerosis the myelin sheath, which is a protective membrane that wraps around the axon of a nerve cell is destroyed with inflammation and scarring, some repair early in disease progress. 40-60% depression, about 10% of population, suicide risk 3-15%, about less than 1%, balance/coordination muscle weakness
Neurons
A-B-E
Afferent neurons, sensory
Brain
Efferent neurons, motor
Interneurons: only found in the CNS, brain tissue, integrate and coordinate activity
Möbius Syndrome
Underdevelopment of 6th cranial nerve (eye) and 7th cranial nerve (lower jaw)- 12 cranial nerves don’t come out of spinal cord, directly out of brain
Difficulty mirroring behavior of others
No known cause:
Maybe genetic, but not clear pattern
Maybe loss of blood flow or oxygen
Emotions
Experience them, appear not to - no mimicry
Is the absence of mimicry advantageous?
About 30% have been diagnosed with autism spectrum
Two Gross Neural Structures in the Nervous System
- Clusters of cell bodies (cell bodies stay in spinal cord or brain)
- Bundles of axons
What is the longest nerve in your body?
Sciatic nerve - all the way to your toe
Anatomy of a Neuron
Image
224 miles per hour
Surface area increases with “fingers”
The Nerve Impulse
- It took time for the signal to get around
2. The signal was about the same strength
Ability to fire depends on membrane potential, which works through two principles…
- Diffusion: things in higher concentration move to a lesser (K+ out, NA+ in)
- Electrostatic Pressure: opposites attract (K+ stay in, NA+ go in)
Membrane Potential Info
Net flow: about 0.003% increase in NA+
Higher K+ in neuron (axon)
Higher NA+ outside neuron (axon)
Closer to zero, more likely to fire
Resting sodium and potassium channels closed
Protein channels control oxygen and carbon dioxide
All or nothing principle
Potassium runs out by diffusion and electrostatic pressure
All happens in the nodes of ranvier
Hyperpolarization
Farther from zero, less likely to fire, inhibit excitation/firing
Depolarization
Closer to zero and more likely to fire, only time you can’t fire again
How do action potentials start?
Temporal Summation: signals coming close together, two high fives one after the other
Spatial Summation: signals coming close in space, double high fives
Action Potential Sequence
- Membrane reaches depolarization (about -55mV)
- Sodium channels open
- Potassium channels open
- About +40mV sodium channels close
- Potassium channels still open for hyperpolarization
- About -70mV potassium channels close
- ATP pump gets to work
Image
Examples of interference with action potentials…
Seizures: toxic accumulation of sodium
Scorpion Venom: blocks potassium channels
Local Anesthisia: blocks sodium channels
Benefits of Saltatory Conduction
- Speed
- Saves energy
Cable property, dendrites and soma, lose momentum
All or none law, axon hillock and axon, send more not stronger messages
So what do action potentials do?
They are the basis for everything you do
Release neurotransmitters into cleft
Active receptor on post-synapse
Kinds of Receptors…
Ionotropic: quick, short lived, info comes and goes quickly
Metabotrophic: long, last longer, behavioral change
What happens to neurotransmitters?
- Diffuse away
- Recycled into Pre-Synaptic cell
- Broken Down by enzymes
SSRI inhibits recycling of serotonin
MAOI inhibits enzyme that breaks down NT
Four Major Groups of Neurotransmitters
- Neuropeptides
Small chain of amino acid
Most are neuromodulators (effect area of brain vs synaptic cleft)
Examples: substance P, Endorphines - Amino Acids (about 20)
8 essential that have to come through diet - Acetylcholine
- Monoamines
Dopamine, epinephrine, and serotonin
Amino Acids:
GABA
GABA
Primary inhibitory NT
Most are ionotropic
Ex. Valium, Xanax, Ativan, benzodiazepines, replaced barbiturates which shit down medulla oblongata, stops breathing, used in seizures to stop looping from spreading in brain, ethanol inhibits glutamate and increases GABA, rebound effect, seizures when you binge drink often raise level with benzos so it doesn’t happen
Amino Acids:
Glutamate
Primary excitatory NT
Excito Toxcisity: neurons excite themselves to death when neurons twist open and sends out glutamate
PCP: delusions, disorientation, hallucinations, blunted affect (mimics schizophrenia)
Micrographics, Parkinson’s, Hitler
Acetylcholine
Earliest discovered NT
Peripheral Nervous System
Muscle action (voluntary)
Central Nervous System
Learning and memory
Attention
Focused (one stimuli) and sustained attention (attention in class)
Acetylcholine in all: learning, retention, and recall
Vitamin B (thymine) stripped away, can’t use Ace, chronic alcoholics, Korsakoff Wrenicke Syndrome, no cure, treated with B1
Curare
Curare results in muscle paralysis, heart works, skeletal muscles can’t function, no running
Small doses were used as muscle relaxants
Botulinum Toxin: prevents release of Ace, Botox
Black Widow Venom: stimulates release Ace, becomes tone, can’t move, Tonic
Alzheimer’s Disease
AchE (enzyme that breaks down Ace) Inhibitor
Donepezil (Aricept)
Tacrine (Cognex)
Monoamines General
Essential Amino Acids turn into monoamines.
Image.
PKU
100% avoidable cause of mental retardation
Screened at birth, turns phenylaline into toxin that kills the brain
Dopamine
Substantia Nigra “black substance” (spot in the brain very rich with dopamine)
D1 (excitation) and D2 (inhibition)
Balanced movements
Ventral Tegmental Area
System that goes from substantia nigra to forebrain, nucleus accumbens, limbic system
Involved in
Goal directed thinking, motivation, regulation affect
Reward, powerful!
Animal studies
Electrical stimulation
Cocaine: blocks DA reuptake
Amphetamine: increase DA release
Nicotine: ACH to DA
Marijuana: GABA to DA
What happens if you block DA receptors? Parkinson's syndromes tortive dyskinesia, positive symptoms go down and negative symptoms go down
Parkinson’s Disease
Loss of dopamine rigid nuclei in substantia nigra
Symptoms
Slow, rigid movements
Poor balance
Tremors at rest, rotational tremors
Dementia as a result (dementia pugalitica)
Similar to CTE, repeated blows to the head
4 in 127 people (movie set virus with Michael J Fox) vs 17 in 100,000 people
Katherine Hepburn, Janet Reno, Pope John Paul II, Billy Graham, Johnny Cash, Harry Truman
What to do to treat PD?
Increase dopamine, too big to make it through blood brain barrier, L-Dopa, makes it through the BBB and gets converted, give corda dopa to prevent conversion in the periphery
Schizophrenia
Dopamine Theory
D2: positive symptoms: things are there but shouldn’t be
D1: negative symptoms
Dopamine blockers
Typical antipsychotics (dirty drugs)
Thorazine
Haldol
Warning: The mechanism of action on this medication has not been entirely determined. However, more effective for negative symptoms and positive symptoms
A–typical antipsychotics (Zy Prexia, Seroquel, Abilify, Resperical), partial agonist opens the door a little moving both to baseline
Mesolimbic system
Nucleus Accumbens, limbic system
Increase in DA causes positive symptoms
Mesolimbic system
Prefrontal cortex (attention, planning, motivated behaviors)
Depletion of DA causes negative symptoms
