Biological Psych - Systems in the body Flashcards
Nature and nurture
- Impossible to separate genetic influences from environmental influences
- They can work together to determine human behaviour
Ex. Caspi et al
MAO-A gene
Epigenetics
Changes in gene expression that are due to non-genetic (‘epi’=outer) influences
Heredity
The genetic transmission of characteristics from parents to offspring
Heritability
- An estimate of the genetic proportion of the variation in some specific trait
- Within a particular population, not an individual
Peripheral nervous system
- Somatic nervous system
- Automatic nervous system
-> Sympathetic nervous system
-> Parasympathetic nervous system
Central nervous system
Brain and spinal cord
Neurons
- The basic unit of the nervous system
- Operate through electrical impulses
- Communicate with other neurons through chemical signals
Types of neurons
- Sensory neurons (afferent neurons)
- Motor neurons (efferent neurons)
- Interneurons
How do neurons communicate?
- Via the action potential
- The neural impulse that passes along the axon and subsequently causes the release of chemicals from the terminal buttons
Resting potential
Polarized state (more negative inside the cell, approximately -70mV)
Excitatory signals
Increase the likelihood that the neuron will fire
Inhibitory signals
Decrease the likelihood that the neuron will fire
How do neurons fire?
By affecting the polarization of the cell
All-or-none principle
- A neuron fires with the same magnitude each time (it either fires or does not fire)
- But how frequently the neuron fires can vary
When do neurons generate an action potential?
If the excitatory input (depolarization) reaches a certain threshold (ex. -55mV)
Resting state (resting potential)
- Neurons are polarized at rest (resting membrane potential ~70mV)
- The inside of the cell is more negative than the outside
- Also, relatively more sodium (Na+) outside and more potassium (K+) inside
Depolarization
- If the neuron reaches its excitatory threshold, it will fully depolarize (generate an action potential)
- All or none principle
- Na+ channels open and the charge across the membrane reverses -> becomes more positive inside the cell, due to influx of Na+
Peak action potential and hyperpolarization
- At the peak of the action potential, Na+ channels will close and K+ channels will open, allowing K+ to leave the cell -> this outflowing of K+ actually leads to a temporary hyperpolarization, during which the cell cannot fire (refractory period)
- K+ channels close, and the cell returns to its (Polarized) resting state
Neurotransmitters
- Are chemical substances that carry signals from one neuron to another
- Are stored in vesicles (small packages) inside the terminal buttons
Glatumate
Primary excitatory neurotransmitter
GABA
Primary inhibitory neurotransmitter
Serotonin
Mood, impulsiveness, hunger, sleep
Dopamine
Reward and motivation, voluntary movement
Acetylcholine
Movement; memory, cognition, sleep
Epinephrine and norepinephrine
Ex. stress response (fight or flight
Presynaptic membrane
Membrane of the neuron that is sending the signal
Postsynaptic membrane
Membrane of the neuron that is receiving the signal
Drugs as agonists
By binding to receptors and producing a response to mimic the effects of an endogenous neurotransmitter.
Drugs as antagonists
- Inhibiting the action of an endogenous neurotransmitter by
- Blocking the release of neurotransmitters
- Destroying neurotransmitters in the synapse
- Mimicking a neurotransmitter (and blocking neurotransmitter binding)
How may drugs enhance the effects of endogenous neurotransmitters?
- Increasing the release of neurotransmitters
- Blocking the re-uptake of neurotransmitters
Neuroplasticity
- The brain is ‘plastic’
- Able to be changed, reorganized, as a result of experience, drugs, or injury (ex. stroke)
Ex. Rats in enriched vs not enriched environments study
Brainstem
- Controls life sustaining functions of the autonomic nervous system, including breathing, digestion, heartbeat, etc.
- Reticular formation
- Alertness
- Sleep
Cerebellum
Essential for coordinated movement and balance
The diencephalon
The hypothalamus
- Tiny but powerful
- Is the brain’s master regulatory structure
- Connects the nervous system to the endocrine system
The thalamus
- Often referred to as a relay station
- Handles all incoming information except smell
The basal ganglia
Producing and planning movement
Hippocampus
- Formation and storage of long-term memory
Ex. HM
Amygdala
- Best known for its role in processing fear
- Essential to our ability to associate things with emotional responses
- Located in front of the hippocampus
Ex. Sharot et al
Cerebral cortex
- The outer layer of the brain; each cerebral hemisphere has four lobes
- The corpus callosum (massive bridge of axons) connects the hemispheres and allows information to flow between them
Parts of the cerebral cortex
- Occipital lobes (vision)
- Temporal lobes (hearing)
- Parietal lobes (touch)
- Frontal lobes (planning, movement)
Peripheral nervous system
- Transmits information to the CNS
- Responds to messages from the CNS to perform certain behaviours or make bodily adjustments
Somatic nervous system
- Concerned with the external environment
- Consists primarily of motor neurons responsible for sending signals from the CNS to the skeletal muscles
- Voluntary motor control; reflex arcs
- Efferent pathway
- Also includes sensory neurons which send signals from the skin, skeletal muscles, and other sense organs to the CNS
- Conscious perception of our environment
- Afferent pathway
Autonomic nervous system
- Concerned with the internal environment
- Efferent and afferent pathways between the CNS and smooth muscles/glands
- Autonomic responses typically involve changes in involuntary bodily functions
Sympathetic nervous system
Prepares the body for action (fight or flight)
Parasympathetic nervous system
- Returns the body to its normal state (rest and digest, feed and breed)
- Opposing functions of the sympathetic system, but the two systems work in a complementary fashion
- Chronic activation of either system can lead to health problems
The endocrine system
- Works with the nervous system to regulate psychological activity
- Whereas the nervous system uses electrochemical signals, the endocrine systems uses hormones
- Hormones are chemical substances released into the blood stream by endocrine glands until they reach the targeted tissues
