Introduction to Biopsychology.

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Index of notes made during portions of a Biopsychology class taught by Terry Fetterman.

• Cells
• Neurons
• PNS and CNS - Neuroanatomy and Physiology
• Brain Components

• Action Potential
• Graded Potential
• Synapse
• Neurotransmitters
• Drugs

• Sensation
• Perception

Cells.

Cells

All living cells have a 'membrane potential' due to the non-uniform distribution of Na+, K+ and large anions [A-] between the inside and outside of its membrane.

Excess of positive outside Excess of negative inside

Cell body

Nucleus and organelles.

Meiosis

meion = less. Number of chromosomes reduced from diploid to haploid number.

Mitosis

mito = thread. Chromosomes split longitudinally.

Neurons

Astrocytes

In CNS. The most numerous glial cells, they are mainly on the outer surface of the brain and around capillaries.

Astroglia

In CNS. Nourish satellite cells.

Axon or nerve fiber

Leaves the cell soma and Conducts action potential away from cell body. Branched endings (axon terminals). Can range from less 1 mm to over 1 meter.

Axon hillock

The start of the axon plus the area of the cell body from which it leaves.

Dendrites

Extend from cell body.

Glial cells

Support of neurons.

Microglia

In CNS; cells that eat debris.

Neuron

excitable cell.

Neuron types

(1) sensory neurons; (2) interneurons; (3) motor neurons.

Nodes of Ranvier

In the myelinated neurons.

Oligodendrocytes

Create myelin sheath around CNS neurons.

Olioglia

In CNS.

Satellite cells

In PNS.

Satellite cells

In CNS. Nourish satellite cells.

Schwann cells

In PNS.

Terminal button

Small knob at the end of an axon that releases neurotransmitters.

Oligodendrocytes

Create myelin sheath around CNS neurons.

PNS and CNS - Neuroanatomy and Physiology

Ascending tracts

Nerve fibers that run toward the brain and are mostly sensory.

CNS

Spinal chord and brain (brainstem, cerebellum, cerebrum).

CNS cells

Two major classes are (1) neurons and (2) glial cells.

CNS tract

Carries commands.

Brain Components

Amygdala

In limbic system. Emotions like rage.

Celebral cortex

External layer of grey matter.

Hippocampus

Long-term and short-term memory.

Metencephalon

Two main structures: (1) Pons; (2) Cerebellum.

Neural Impulse.

Action Potential

1. Action potentials are long-distance signals
2. Polarization = separation of charges.
   Depolarization = reduction in potential.
   Hyperpolarization = increase in potential.
   Repolarization = return to resting potential.
   Voltage-gated channel = ion channel that opens and closes in response to changes in membrane potential.
3. Events
   Start at Resting Potential (-70 mV): many K+ channels open; most Na+ (voltage-regulated) channels closed,
   Receives Triggering event.
   Slow depolarization from -70 mV to -50 mV (threshold); some Na+ channels open; at threshold (-50 mV) 'all' Na+ channels are open.
   Abrupt depolarization to +30 mV. Na+ rushes in.
   At +30 mV, voltage-sensitive Na+ channels close. All K+ channels are open; K+ rushes out of cell along concentration gradient and electrical gradient.
   Repolarization
   Hyperpolarization (-80 mV); K+ rushes out taking extra positive charges.
   1 millisecond.
   Na+/K+ pump.

Graded Potential

1. A small (under 10mV) short-range (local) change in membrane potential.
2. Magnitude of change depends on the size of the triggering event.
3. A triggering event causes a flow of ions across the cell membrane (e.g., a flow of Na+ into a cell).
4. A local change in membrane potential results.
5. Dies out if triggering event fades.

Synapse

• What is a synapse?
  The end of a nerve, which, when stimulated, will touch another nerve ending while releasing vesicles (little containers) filled with neurotransmitters. After the chemical has been released, it must be deactivated through reuptake (reabsorbtion by the nerve that released it in the first place) or the release of an enzyme that changes the structure of the chemical so it's no longer recognized by the receptor (deactivation or degradation).

• What is a synaptic cleft?
  Where an electrical signal jumps from one neuron to another. The impulse cannot cross a gap as electricity. Therefore it crosses as a 'message' by means of chemical messengers called neurotransmitters.

Neurotransmitters

1. What is a neurotransmitter?
   A chemical that transmits information across nerve synapses.

2. What is Serotonin [5-HT]?
   • Affects blood clotting, heart beat, sleep, depression, migraine headaches (can cause blood vessels to constrict or spasm), and body clock.
   • 17 types of serotonin receptors found all over your body. Each selective serotonin reuptake inhibitor [SSRI] blocks a different group of serotonin receptors from reabsorbing the chemical serotonin. [Prozac works on all 17 types of receptors. Therefore possibility for side effects is high, particularly in stomach and intestines.]

   • Different Serotonin Receptors and Their Effects: 
     
     5-HT1A: Controls mood. 
     
     5-HT1B: Controls release of other neurotransmitters, such as dopamine; has 
     analgesic (pain relief) and anti-depressant properties. 
     Mice lacking this receptor show more aggression and an increase in 
     desire for alcohol.
     
     5-HT1F: May be linked to migraine headaches.
     
     5-HT2A: Controls contraction in vascular, urinary, gastrointestinal, and uterine functions. 
     Drugs that block this receptor may improve sleep quality.
     
     5-HT2B: Reduces anxiety, agitation, or tension. May be linked to migraines. 
     
     5-HT2C: May regulate production of cerebral spinal fluid. May affect penile 
     erection and sleep. 
     Mice lacking the 5-HT2C receptor suffer from convulsions, obesity, 
     and cognitive impairment (difficulty in thinking/learning). 
     
     5-HT3: Affects cardiac function, dilation of blood vessels; 
     lungs and intestines, may cause nausea and vomiting in response to pain.
     
     5-HT4: Associated with dopamine function. Affects colon and bladder 
     contraction, and bodily secretions. May induce tachycardia (rapid heart rate). 
     Possibly linked to controlling anxiety. 
     
     5-HT6: Perhaps stimulates yawning and stretching?
     
     5-HT7: Affects relaxation of smooth muscle tissue.
     

3. What is Dopamine [DA]?
   • DA modulates (stabilizes] brain activity, controls movement, & regulates the flow of information to other areas of the brain.
   • DA may release chemicals that allow us to feel pleasure.
   • The brain's lack of DA in the brain can produce Parkinson's Disease or schizophrenia.
   • Effect of cocaine.
     Cocaine blocks the re-uptake pumps that remove DA from the synapse. DA accumulates in the synapse -> intense pleasure.
     Prolonged cocaine use make the brain adapt and require cocaine to function normally. It 'downregulates' the natural amount of DA; and the opposite of pleasure is depression and fatigue.

4. What is Norepinephrine (noradrenaline) [NE]?
   • NE is in sympathetic nervous system [SNS in the thoracic and lumbar regions of the spinal cord]. SNS stimulates: heart, blood vessels, sweat glands, the large interior organs, and the adrenal medulla in the brain.]
   • NE causes physiological expressions of fear and anxiety. People with anxiety disorders have excess NE.

5. What is GABA?
   
   • GABA quiets electrical activity in the brain. When it occupies a receptor, it decreases the neuron's electrical activity. When released from the receptor, GABA is removed from the synapse by reuptake pumps that return it to the first neuron.
   • Addition of alcohol.
     Alcohol binds to GABA receptors, and increases the quieting effect that GABA has on neurons. [Possibly alcohol causes the ion channels to stay open longer, which increases the ion flow.]

     Alcohol sedates judgment, movement, and even breathing. Prolonged alcohol use causes the brain to adapt and to depend on the presence of alcohol to function normally.

   • What do receptors do?
     These cells are specialized to receive chemical, mechanical, or radiant signals from the environment.

Drugs

1. SSRIs (selective serotonin re-uptake inhibitors)
   
   • Alleviate depression.
   • paroxetine (very short half-life, Paxil); fluoxetine (very long half-life, Prozac); sertraline (Zoloft); fluvoxamine (Luvox); citalopram (Celexa)
   • Acute side effects occur early in treatment: stomach upset, nausea, fatigue, headache, fatigue, tremor, nervousness and dry mouth (helped by taking vitamin C tablets).
   • Chronic side effects: daytime fatigue (sedation), insomnia (stimulation) especially with Prozac, sexual problems (especially problems experiencing an orgasm), and weight gain (paroxetine).
   • Some patients, particularly those over 35 or with medical problems, may experience a change in EKG (electrocardiogram) readings that measure certain heart function. For this reason, it is important to consult a physician before taking these medications.
   • SSRIs pose greater risks when taken with other drugs; SSRIs can be lethal when taken with MAOIs.
   • SSRIs have been proven to increase thoughts of suicide or self harm.
   • 50% of patients get loss of desire, impaired arousal or lubrication, delayed or impaired ejaculation or orgasm.
   • Established direct link between suicide and violent behaviour and the use of SSRIs.
   • Drug holiday can cause serotonin withdrawal symptoms (dizziness, depressed mood, nausea, and confusion).
   • tend to have fewer and different side effects, such as nausea, nervousness, insomnia, diarrhea, rash, agitation, or sexual side effects (problems with arousal or satisfaction). Bupropion generally causes fewer common side effects than TCAs and MAOIs. Its possible side effects include restlessness, insomnia, headache or a worsening of preexisting migraine conditions, tremor, dry mouth, agitation, confusion, rapid heartbeat, dizziness, nausea, constipation, menstrual complaints, and rash. Bupropion (Wellbutrin) [SSRI? SNRI?] was temporarily removed from the market due to seizures in some patients - associated with high doses (above the current maximum recommended dose of 450 mg/day), a history of seizures or brain trauma, an eating disorder, excessive alcohol use, or taking other drugs that can increase the risk for seizures.
   • http://www.clinical-depression.co.uk/Treating_Depression/side_effects.htm says "St. John's Wort (hypericum) has been shown to be as effective as antidepressants, and [to] have fewer side effects."

2. Tricyclic antidepressants (TCAs)
   
   • Those over 35, or with medical problems, should have an EKG prior to starting a tricyclic antidepressant.
   • greater side effects: dry mouth, postural blood pressure changes (-> dizziness), constipation, difficulty urinating, blurred vision, weight gain, drowsiness.
   • o/d potentially lethal: rapid heartbeat, dilated pupils, flushed face and agitation; then confusion, loss of consciousness, seizures, irregular heart rate, cardiorespiratory collapse, death.

3. MAOIs: Monoamine oxidase inhibitors (MAOIs), including newer MAOIs called selective MAOIs
   • risk of dangerously high blood pressure if certain foods or medications are consumed while on a MAOI: foods like aged cheese with a high level of tyramine (builds up if ingested while on a MAOI). Other problems are certain smoked, fermented, or pickled foods, certain beverages, or some medications (can cause severe high blood pressure in combination).
   • Less serious side effects: weight gain, constipation, dry mouth, dizziness, headache, drowsiness, insomnia, and sexual side effects. Patients carry an 'antidote' (such as nifedipine) to use if they experience signs of elevated blood pressure.
   • Rare: liver inflammation, heart attack, stroke, and seizures.

Sensation and Perception.

• 8 senses: 5 plus balance (vestibular, inner ear), body position (kinesthetic, limb position), and magnetic sense. Women orient better by landmarks. Men (after being blindfolded and led through a labyrinth) are better at pointing back to where they originated.

1. What do receptors do?
   These cells are specialized to receive chemical, mechanical, or radiant signals from the environment.

2. What is transduction?
   Changing energy from one form to another.

3. Anatomical versus functional coding.
   'Somatotopic organization of the motor cortex -> a movement can be learned with one extremity and performed with another. ... there exists a limb-independent coding for movements. ' (2) 'somatotopy in secondary structures in the human motor system seems to be defined functionally, and not on the basis of anatomical representations.'

4. What is light?
   = Energy.
   The colors of the spectrum?
   = ROY G. BIV.
   How does wavelength relate to color?
   Long = red. Short = blue.

5. Anatomy and physiology of the eye.
   • Cornea =Transparent tissue at front where light is 1st bent.
   • Fovea = visual acuity; +/- 5 degrees.
     
   • Lens = behind lens; focuses light on retina.
     
   • Other cells =
     
   • Optic nerve = transmits electric impulses from retina.
     
   • Retina = where light is converted into electrical impulses.
     
   • Other cells =
     
   
   

6. Audition. What is sounds?
   = Pressure waves. Compression and rarefaction. 20 Hz to 20,000 Hz.

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