Introduction to Biopsychology.
Index of notes made during portions of a
Biopsychology class taught by Terry Fetterman.
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
-
Action potentials are long-distance signals
-
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.
- 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
- A small (under 10mV) short-range (local) change in membrane potential.
- Magnitude of change depends on the size of the triggering event.
- A triggering event causes a flow of ions across the cell membrane (e.g., a flow of Na+ into a cell).
- A local change in membrane potential results.
- 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 re-uptake (re-absorption 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
- What is a neurotransmitter?
A chemical that transmits information across nerve
synapses.
- 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.
- 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.
- 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.
- What is GABA?
Drugs
Four classes:
- Opiates/narcotics — endorphins.
- Hallucinogens — serotonin.
- Stimulants — dopamine.
- Depressants — increases sensitivity to GABA, which decreases anxiety.
Nearly all antidepressants are metabolized in the liver, so anyone with liver abnormalities should use them with caution.
- 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."
- 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.
- 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.
- What do receptors do?
These cells are specialized to receive chemical,
mechanical, or radiant signals from the environment.
- What is transduction?
Changing energy from one form to another.
- 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.'
- What is light?
= Energy.
The colors of the spectrum?
= ROY G. BIV.
How does wavelength relate to color?
Long = red. Short = blue.
- 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 =
-
Audition. What is sounds?
= Pressure waves. Compression and rarefaction.
20 Hz to 20,000 Hz.
[Thanks for visiting.]
Death and Dying.
Books read recently.
