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The Reflex Action
Processed in the spinal cord (not the brain). Afferent system -> interneuron pathway -> spinal cord -> efferent system -> muscle contracts
Neurons
A nerve cell, specialized design to carry and transmit information electrochemically
Sensory (Afferent) Neurons
Toward central nervous system
Motor (Efferent) Neurons
Away from central nervous system
Interneuron
The rest of neuron cells; greatest number, between sensory and motor neurons. Contained mostly in the central nervous system
Neural Transmission
Dendrites -> soma -> axon -> terminal buttons
Dendrites
Receive information from different sources
Soma
Main body of the cell. Contains genetic material. Processes information; doesn't go through regular cell division
Axon
Transmits information
Terminal Buttons
Part of the axon; release neurotransmitters into the synapse (gap)
Synapse
Tiny gap between terminal buttons of one neuron and the dendrite of the next one
Glial Cells
Central nervous system support cells (10x more plentiful than neurons)
Action Potential
Travels down the axon in a chemical chain reaction (neuron "firing"). 1.) Neuron receives information 2.) Sodium channel opens, + charge 3.) When threshold voltage is reached, action potential fires (Excitatory messages -> Depolarization) Faster if neuron is mylenated
Neurotransmitters
Flow into the synapse from the terminal buttons
Hyperpolization
Staying at rest. Cell becomes more negatively charged when some neurotransmitter (GABA) inhibit neuron from firing; let - chloride in, + sodium out.
Acetylcholine
Excitatory; voluntary muscle contraction, memory (Alzheimer's)
Dopamine
Modulating effect; smooths out movement, emotional response, and ability to experience pleasure/pain (Parkinson's, Huntington's)
Serotonine
Inhibitory (more negative); mood, arousal, alertness (depression)
Agonist (goes with)
Bind to neurotransmitter receptors; MIMIC THE ACTION OF NEUROTRANSMITTERS (Nicotine mimics AcH)
Antagonist (goes against)
BLOCKS THE ACTION OF NEUROTRANSMITTERS (Curare blocks AcH)
Neuromodulator
MODULATE THE EFFECTIVENESS OF OTHER EXISTING NEUROTRANSMITTERS
Central Nervous System
Brain and spinal cord
Peripheral Nervous System
1.) Somatic: consciously perceived sensations. Skeletal muscles, produces conscious, voluntary movements. 2.) Autonomic (regulated by hypothalamus and brain stem): Smooth/cardio muscle or grandular secretion
Sympathetic vs. Parasympathetic
Sym: Prepares body for emergencies Parasym: Calms body down
STUDYING THE BRAIN
Electro-encephalo-graph (EEG)
Electrical activity in the brain recorded, can show active areas of the brain
Computerized Tomography
Essentially an X-ray. Shows structure, but not function. Denser tissue blocks rays (darker/lighter)
Positron Emission Tomography (PET)
Radioactive material attached to glucose or oxygen shows brain activity. More active areas take up more radioactive dye
Magnetic Resonance Imaging (MRI)
Provides detailed anatomical view of the brain
fMRI
Studies brain function
Hindbrain
Main function: Basic life support. Controls heart rate, blood pressure, respiration. Contains medulla, pons bridge, cerebellum
Midbrain
Structures that help coordinate and relay information to higher centers. Coordinates sensory information, releases dopamine
Forebrain
"Higher" mental processes. Cerebral cortex: 80% of brain mass Thalamus: screens/combines sensory input Hypothalmus: Motivation/drive Limbic System: Hippocampus forms memory, Amygdala forms fear, anger, aggression
LOBES
Frontal Lobe
Planning, decision making, memory, personality
Parietal Lobe
Process sensations of touch, temperature, pain
Temporal Lobe
Auditory processing, speech, language comp (left hemisphere)
Occipital Lobe
Vision
Corpus Callosum
Directly transfers information across hemispheres
Endocrine System
Communication system that sends HORMONES through the body via the BLOODSTREAM. Hypothalamus controls pituitary gland, pit. gland controls secretion of hormones from sites in the body
Twin Studies
Monozygous: One egg, identical, same sex, same genetic material Dyzygotic: Two eggs, fraternal, related but not identical genetic material
Genetic Variation
Genetic/Recessive genes for traits (eye color). Genotype: Genetic program DNA Phenotype: Expression of a particular trait (physical)
STAGES OF PRENATAL DEVELOPMENT
Germinal Period
0-2 weeks - Conception to zygote implantation
Embryonic Period
2-8 weeks - Heartbeat, recognizable body parts, sexual differentiation
Fetal period
9th week - birth - Last three months is rapid growth of body/brain
Teratogens
Environmental agents that can damage the developing child Ex: Fever, German measles
In-Utero Brain Development
- From 8-16 weeks (fetal period), GLIAL CELLS develop brain structure and neurons migrate - Brain develops 250,000 neurons/minute ALCOHOL causes OVER MIGRATION, RADIATION causes UNDER MIGRATION
Motor Development
Babies crawl, stand, and walk at roughly the same ages. "Top DOWN inside OUT" for what can be controlled. Pincer grip 8-10 months
Cognitive Development (3 Periods, Big Brain Changes)
1.) In utero/infancy (up to 18 months): Over produced gray matter, followed by pruning 2.) Early adolescence (11-12 years): Pruning, connections lost, end of critical period for languages 3.) Late adolescence (early 20s): Frontal lobe changes
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