central nervous system (cns)speedwaybiology.weebly.com/.../ap_biology_-_chapters_48_and_49_p… ·...
TRANSCRIPT
Central nervous system (CNS) = brain + spinal cord Peripheral nervous system (PNS) = nerves
throughout body
Sensory receptors: collect info
Sensory neurons: body brain/SC
Motor neurons: brain/SC body (muscles, glands)
Interneurons: connect sensory & motor neurons Nerves = bundles of neurons
Contains motor neurons +/or sensory neurons
Peripheral nervous system
Somatic nervous system
Autonomic nervous system
Sympathetic division
Parasympathetic division
Enteric division
cell body: nucleus, organelles dendrites: receive incoming messages axons: transmit messages to other cells myelin sheath: insulates axon, speeds up nerve impulses synapse: junction between 2 neurons neurotransmitter: chemical messengers sent across
synapse
Eg. acetylcholine, dopamine, serotonin glia (glial): support cells
Astrocytes, oligodendrocytes (forms CNS myelin sheath), Schwann cells (forms PNS myelin sheath)
Microelectrode
Reference electrode
Voltage recorder
–70 mV
A Na+/K+ pump maintains a negative potential inside the neuron.
Resting potential: membrane potential at rest
Voltage-gated Na+ channel = closed High Na+ outside / High K+ inside cell Nerve impulse: change in membrane potential =
action potential
Action potential – neuron membrane depolarizes and causes all-or-nothing response
Voltage-gated
Na+ channels
open
Na+ enters cell K+ channels
open K+ leaves cell
Conduction of an action
potential
Saltatory conduction speed: 120 m/sec
Released by presynaptic membrane into the synaptic cleft
Bind to receptors on postsynaptic membrane, then broken down by enzymes or taken back up into surrounding cells
Types of neurotransmitters:
Excitatory: speed up impulses by causing depolarization of postsynaptic membrane
Inhibitory: slow impulses by causing hyperpolarization of postsynaptic membrane
Acetylcholine: very common neurotransmitter, can be excitatory or inhibitory
Other common neurotransmitters: epinephrine, norepinephrine, dopamine, serotonin
Nicotine: mimics acetylcholine – speeds heart rate LSD/mescaline – bind to serotonin and dopamine
receptors hallucinations Prozac – enhances effect of serotonin by inhibiting
uptake after release Morphine, heroin – bind to endorphin receptors
decrease pain perception Viagra – increase NO (nitric oxide) effects maintain
erection Parkinson’s Disease – lack of dopamine Alzheimer’s Disease (AD) – develop senile plaques,
shrinkage of brain tissue
Simple, automatic response to a stimulus Conscious thought not required Stimulus detected by receptor sensory
neuron interneuron (spinal cord) motor neuron cause effector (muscle or gland cell) to respond
Gray matter
White
matter
Ventricles
Structure Function
Brainstem *Oldest evolutionary part* Medulla oblongata – control breathing, circulatory
Cerebellum Motor, perception, cognitive functions
Thalamus Main center for sensory info
Hypothalamus Homeostasis (body temp, appetite, thirst, circadian rhythm, hormones), basic survival behaviors
Cerebrum Information processing (thinking, memory, personality, interpretation of sensory input)
Corpus callosum Connect hemispheres