【3】Biopsychology - Notes

 

☆ seeks to explain the biological mechanisms that underlie behavior

- ⭐ Each human body is unique

- ⭐ Darwin's theory of natural selection

        ↪ survival of the fittest - animals that are better suited 

            to the environment will pass on their traits

Sickle Cells

• Sickle-cell anemia (SCA) is a genetic condition where some of a person's blood cells have a crescent shape

• This condition still persists in places like Africa because it grants the carriers resistance and immunity to malaria.
• Those with 2 of the SCA aren't immune to malaria.

• Carrier - has one copy of a gene instead of 2; doesn't necessarily show symptoms of diseases resulting from the gene

Genetic Variation - genetic differences between individuals that contribute to a species' adaptation to its environment

• Phenotype - physical characteristics with genetic & environmental factors
• Genotype - genetic makeup of someone

Genes - parts of DNA with instructions for making a protein

Alleles -  different variations of a gene

Chromosomes - long strands of DNA that contains genes

        Homologous chromosomes - pair with the same genes but not necessarily the 

        same alleles

Traits can be controlled by 1 or multiple genes

         ↪ Polygenetic - controlled by more than 1 gene

Punnett Square - only used for traits with 1 gene

⭐ dominant and recessive alleles

Homozygous - 2 copies of the same alleles

Heterozygous - combination of alleles

Mutation - sudden and permanent change in a gene

         ↪ can be beneficial, harmless, or harmful

         ↪ provides variability in genes for adaptation

Range of reaction theory - states that genes set the boundaries of our potential and the environment determines how much of that potential can be achieved

         ↪ Counterarguments - 1) genes don't set limits on behavior 2) environment plays a 

                                                    larger impact on overall behavior

Gene-Environment Correlation - genes influence environment and vice versa on expression of genes

⭐Genes alone don't determine a person's future⭐

Epigenetics - studies how the same genotype ca lead to different phenotypes

          ↪ identical vs fraternal twins

The Nervous System

Made up of 2 types of cells:

• Neurons - build blocks/information processors for all tasks in the nervous system
• Glial - for structural support of the neuron and transports nutrients and waste products

Neuron structure

• surface has semipermeable membrane 
• allows smaller and or molecules without electrical charge to pass

⭐dendrites -> soma -> axon(+myelin sheath & nodes of Ranvier) -> terminal buttons⭐

Neural signals the axon and into the terminal buttons where synaptic vesicles release neurotransmitters (NT) into the synaptic cleft - a small space between two neurons where communication between neurons take place

Once the NT are released, they travel across the synaptic cleft and bind with the correct receptors on the dendrite of the next neuron

• lock-and-key relationship - receptors vary in shape in order to ”match” different NT 

Neuronal Communication

The neuron is surround by extracellular fluid and contains the cytoplasm; the neuronal membrane keeps these fluid separate

• membrane potential - difference between charges outside and inside the cell; provides energy for the signal to move through the neuron
• electrical charge of each fluid is determined by the ions dissolved in it
• membrane restricts movement -> difference in concentration
• Na+ is concentrated outside while K+ is concentrate inside
• Inside the cell is slightly negative, pulling Na to come into it
• resting potential - neuron has no current signal but is ready to receive one

⭐signal -> dendrites, neuronal gates open -> Na+ floods into the cell because of the charge and concentration difference⭐

threshold of excitation - limits how positive the cell can get due to Na+ permeating; begins the action potential

action potential - electrical signal that moves from soma to axon to terminal; causes spike in charge (+ principle of all or nothing)

• more pores open-> Na+ gates close; K+ gates open 

repolarization - peak of action potential

hyperpolarization - cell becomes more negative than its resting potential then levels out and returns to rest

action potential jumps between the nodes of Ranvier - used as areas for recharging (more Na+ entering) until threshold of excitation -> action potential flows at full strength through axon through the end

        -      NT is then released out of the synaptic vesicles into the synaptic cleft...

        -      ...then binds to the receptors of the adjacent neuron

Excess transmitters either 1) drift away and broken down 2) reabsorbed via reuptake (NT gets pumped back into the neuron it came from)

        -     Clearing the synapse provides an off and on mechanism for NT production; if 

               its full, then no additional NT will be made

action potential movement (electric), NT movement (chemical)

gap junction - physically connects two cells for the to communicate via electrical synapse

Neurotransmitters and Drugs

Psychotropic medications - drugs that treat psychiatric symptoms  by restoring balance in NTs

        agonist - mimics NT at receptors

        antagonist - blocks NT activity

Parkinson's - caused by low dopamine; treated with dopamine agonists

Schizophrenia - overactive dopamine; treated with antagonists

Depression - lowered serotonin; treated with selective serotonin reuptake inhibitors

Reuptake inhibitors - prevent unused NT from being transferred to another neuron

       ↪ Causes NT to remain active in the synaptic cleft, which increases potency

Central nervous system (CNS) - Brain + spinal cord

Peripheral nervous system (PNS) - connects CNS to the rest of the body 

        ↪ contains nerves that transmit signals to and from CNS and muscles, organs, and 

            senses

• Somatic NS - for conscious and voluntary actions
• Sensory neuron - carries info from senses to CNS; afferent (towards/arrive)
• Motor neuron - carries info from CNS to muscles; efferent (away/exit)
• Autonomic NS - controls involuntary actions in organs, glands, etc.
• sympathetic NS - deals with stress and the fight or flight response
• parasympathetic NS - for everyday body functioning; returns body back to a normal state after activation of the sympathetic NS

Brain and Spinal Cord

Brain 

- made of billions of interconnected neurons and glia

- has 2 hemispheres separated by the longitudinal fissure

- separated into 4 lobes with different functions that 

   work together

Spinal cord

 - can act as a processing center without help from the 

   brain (reflexes)

- protected by bony vertebra and cerebrospinal fluid

Neuroplasticity - refers to how the nervous system changes and adapts; new synapses gets created and unused ones gets pruned, changes into glial cells and becomes neurons

Lateralization

• Left hemisphere controls the right half of the body; associated with verbal expression, logic, memory, and selective attention

• Right hemisphere controls left half of the body; associated with nonverbal expression, creativity, and arousal

Corpus Callosum - connects and links up the two hemispheres

Forebrain

• cerebral cortex - outer surface of the brain
• gyri - folds and bumps in the cerebral cortex
• sulci - grooves in the cerebral cortex
• Frontal lobe - reasoning, motor control, emotion, and language
• motor cortex
• prefrontal cortex - complex behaviors
• Broca's area - producing language
• Parietal lobe - processes senses
• somatosensory cortex - processes things like touch, temperature, and pain
• Occipital lobe - awareness of visual stimuli
• primary visual cortex - interprets information from your sight
• Temporal lobes - hearing, memory, emotion, and language
•  auditory cortex
• Wernicke's area - comprehending speech
• thalamus - sensory relay for brain except for smell
• pituitary gland
• limbic system - emotion & memory; smell can be tied to emotional responses
• hippocampus - learning & memory
• amygdala - expression of emotions and tying them to memories
• hypothalamus - regulates body temperature, appetite, and blood pressure
• + sexual motivation and behavior
• connects NS to endocrine system

Midbrain

• reticular formation - regulates sleep/wake cycle, arousal, alertness, and motor activity
• substantia nigra - produces serotonin
• ventral tegmental area - produces dopamine

Hindbrain

• medulla - controls autonomic nervous system and breathing, blood pressure, and heart rate
• pons - regulates brain when you're asleep
• cerebellum - receives signals from muscles, tendons, joints, and ears; for coordination, movement and motor skills

Imaging Techniques

computerized tomography (CT) scan - uses x-rays to create an image of the area being scanned

positron emission tomography (PET) scan - creates pictures of the living brain using a slightly radioactive substance to trace regions in the brain using blood flows

magnetic resonance imaging (MRI) - magnetic fields from the body used to generate an image of tissues

functional magnetic resonance imaging (fMRI) - shows metabolic changes and activity and tracks blood flows and oxygen levels