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Chapter 2-biological bases - Coggle Diagram
Chapter 2-biological bases
Neuron
Structure
Dendrite
Branching extensions that receive messages and conduct impulses towards the cell body
Axon
Extension that passes messages through branches to other neurons, muscles and glands
Cell body(soma)
Cell's life support center
Myelin sheath
Fatty tissue layer around axon to speed neural impulses
Cell nucleus
Provide energy for neuron
Schwann cell
Non-neuron cell generates myelin sheath
Node of ranvier
Gap between myelin sheath
Axon terminal
End of axon containing neural transmitters
Synapse
Junctions of axon of sending neuron and dendrite of receiving neuron
Synapse gap
Tiny gap between sending neuron and receiving neuron
Neurotransmitters
Chemicals released from sending neuron, crossing synapse and binding with receptor site of receiving neuron
Neural firing process
Inner neuron communication
Membrane potential
Inside membrane is negative charge and outside is positive charge
Resting potential
When a neuron is not firing and with mostly potassium ions inside sodium ions outside
Polarization: at resting potential and with potassium ions inside sodium ions outside
Homeostasis: normal happy resting stage
Action potential
Nerve impulse: electrical pulse traveling the length of axon
Depolarization: sodium ions(+)rush in and cause potassium ions(-) rush out
All-or-nothing response: depolarizing current exceeds the threshold a neuron would fire, but no halfway
Intensity of action potantial would remain the same
Refactory period
Period after firing, neuron is focused on resetting and unable to re-fire
Depolarization: sodium channels eventually fully open and sodium is pushed out until voltage becomes negative
Hyperpolarization(sodium-potassium pump): Once sodium channel back to most close but leaky, the more negative potential inside pill be back to resting potential
Reuptake: neurotransmitters are reabsorbed to sending neuron to avoid sending same message again
Neurotransmitters
Serotonin
Mood, hunger, sleep and arousal
Undersupply: depression
Dopamine
Influence movement, learning, attention and emotion
Oversupply: schizophrenia, undersupply: tremors and Parkinson's disease
Norepinephrine
Arousal and mood
Undersupply: depress mood
GABA
major inhibitory neurotransmitter
Undersupply: seizures, tremors, insomnia
Acetylcholine(ACh)
Function: enable muscle action, learning and memory
Malfunction: Alzhelmers disease
Glutamate
Major excitatary neurotransmitter, involve in memory
Oversupply: overstimulate brain to produce migrains and seizures
Drugs on neuron firing
External substances fitting in receptor site
Agonists
Mimic neurotransmitter activity
Antagonists
Block neurotransmitter activity
Psychoactive drug(chemical substance altering perception and mood)
Tolerance: continued use lessens effect
Withdrawl: stop taking and have undesirable effect
Dependence: physical and psychological when absence
Common examples
Stimulants: speed up body processes, euphoric
Depressants: slow down body system
Hallucinogens: change perceptions of reality
Opiates: painkiller and mood elevator, but highly addictive
Nervous system
Body's speedy, electrochemical communication system
Central nervous system: center
Decision maker
Brain: control center
Spinal cord: nerves highway to transmit messages between brain and body
Peripheral nervous system: sensory and motor neurons connecting CNS to rest of the body
Gather information and transfer it
Somatic system
Control voluntary movements and communicate with sense and organ
Autonomic system
Sympathetic system
Arouse the body: prepare it to act/react under stressful circumstances and expend energy
Parasympathetic system
Calm body: conserve energy and keep a constant internal stage
Control involuntary functions happening automatucally
Types of neurons
Interneurons
Messenger between two neurons within CNS
Motor neurons(efferent)
Carry outgoing information from CNS to muscles and glands
Sensory neurons(afferent)
Carry incoming information from sense receptors to CNS
Endocrine system
Support sympathetic system
Body's slow chemical communication system by releasing hormones into specific bloodstream
Glands
Gonads: regulate bodily development(secondary sex characterostics) and maintain reproductive organs in adults to produce sperm and eggs
Pancreas: regulate level of glucose in blood
Adrenal gland: regulate "fight or flight" response and metabolism
Thyroid and parathyroid glands: regulate metabolic, physical growth and development and calcium rate
Pituitary gland: regulate activity of all other glands in system, controlled by hypothalamus to send out hormone signals to other glands
Brain
Techniques
Brain lesion: experimentally destroy brain tissues for scientific medicinal purposes; function
CAT(CT)scan: combine X-ray images from different angles; structure
Electroencephalogram(EEG): amplified recording of electrical waves across brain surface measuring by electrodes; function
MRI scan: use magnetic fields and radio waves to produce computer-generated images distinguishing among types of brain tissues; structure
fMRI scan: measure brain activity by detecting blood flow changes when patients interacting with information; function and structure
PET scan: take picture of radioactive form of glucose to observe metabolic processes in body and brain; function
Structure
Hindbrain
Brainstem: oldest part from spine to skull, responsible for automatic survival functions
Pons: passing neural information from one brain region to spinal cord
Medulla: control involuntary actions liked breating and heart rate
Cerebellum: coordinate voluntary movements and balance
Midbrain
Midbrain: visual and auditory reflexes
Reticular formation: reticular activation system controlling arousal
Forebrian
Limbic system
Amygdala: emotion of fear and anger
Hippocampus: process new memories
Thalamus: direct messages to sensory area in cortex and transmit replies to celebellum and medulla
Hypothalamus: direct maintenance activities like eating and body temperature, help given endocrine system by pituitary gland
Cerebral cortex: ultimate control and information processing center; 80% of brain's total mass
Corpus callosum: connect between two cortical hemispheres, transfer information
Frontal lobe
Judgement, planning
Speech
Emotions, temperament, personality
Motor cortex(movement)
Parietal lobe
Spacial sense and navigation
Somatosensory cortex
Touch
Pressure
Pain
Temperature
Occipital lobe
Primary visual cortex
Each piece of cortex corresponds to a particular area of retina
Temporal lobe
Primary auditory cortex
receive information from opposite ear
speech and language understanding
store longterm memory
Association area
Broca's area
Left frontal lobe: muscle movements in speech
Wernicke's area
Left temporal lobe: languages comprehension and expression
Brain plasticity(neuroplasticity)
Brain's ability to continuously change throughout one's life due to its use(if you don't use it, you lose it)
Hemispheres
Crisscross fashion: right hemisphere controls left body and vice versa
Sleep and dream
Sleep
Circadian rythms: 24 hour cycle of sleep and wakefulness
Controlled by hypothalamus, suprachiasmatic nucleus(SCN)
Light to SCN to pineal gland stop releasing melatonin, darkness to SCN to pineal gland increase releasing melatonin
Basic sleep cycle: studied by EEG to record brain waves; 90 min a cycle, 4-6 cycles a night
Awake: low EEG of 8-25Hz
NREM: quiet sleep
Light sleep
Stage 1: low EEG of 6-8Hz, fantastic imageries and auditory hallucinations(10 min)
Stage 2: medium EEG of 4-7 Hz, sleep spindles and K complex of short burst of brain activity(20 min)
Deep sleep(brain activity significantly slowed)
Stage 4: high EEG less than 2, deepest sleep inly occurring in first few sleep cycles
Stage 3: high EEG of 1-3Hz, transitional stage to deeper sleep
REM sleep: low EEG more than 10 Hz
Paradoxical sleep: awake-aroused state from stage 4 back to stage 1, rapid eye movements and vivid dreams, active brain and paralyzed muscle
Sleep deprivation
Sleep is a necessary biological function, not enough sleep may lead to many problems
Main sleep period and smaller sleep period after 12 hours of middle of main sleep period
Sleep theories
Sleep recuperate: sleep restore and repair brain and body tissue
Sleep helps remembering: sleep restore and rebuilds fading memory
Sleep protects: sleeping in darkness keep ancestors from predators
Sleep and growth: during sleep pituitary gland releases growth hormone
Sleep disorders
Sleep apnea 窒息
Night terror 夜惊
Narcolepsy 嗜睡
Somnambulism/sleep walking 梦游
Insomnia 失眠
REM behaviour disorder REM睡眠期行为障碍(act out dreams instead of paralyzing)
