Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
54 Cards in this Set
- Front
- Back
Cell body
|
metabolic center of cell
|
|
Info conveyed by AP
|
determined by pathway signal travels in brain
|
|
Predominate neurons in NS vertebrates
|
Multipolar
|
|
Simplest neurons
|
unipolar: have single primary process giving rise to many branches
|
|
Predominate neurons in invertebrates NS
|
Unipolar (in autonomic NS in verbtebrates)
|
|
Pseudo-unipolar cells
|
receptor neurons convey touch, pressure, pain signals to spinal cord
|
|
Oligodendrocytes
|
wrap axons of neurons in CNS
|
|
Schwann cells
|
Wrap axons of neurons in PNS
|
|
Astrocytes
|
Star shaped, large end feet, provide nourishment, insulation, regulate K+
|
|
the neuron doctrine
|
the NS is composed of cells
|
|
Jan Evangelista Purkyne
|
first to represent cells in the brain
|
|
Deiter's (1865)
|
First observed neurons after dissection (spinal cord)
|
|
Staining techniques
|
Developed in 1860s; revealed tangle dendrites & axons of neurons but most anatomists in 60-90s thought NS was reticulum (fused cells)
|
|
Camilio Golgi 1843-1926
|
Method revolutionized neuroanatomy: growth of silver chromate crystals within 2 neurons
|
|
Cajal's evidence for contact but not connection
|
basket cells in a kitten cerebellum, purkinje cells: made use of Camillo Golgi's silver dichromate staining technique in 1887: reazione nera (black rxn) stained 1% of neurons completely black while 99% left unstained: neurons completely separated from one another & did not fuse
|
|
Corollaries of neuron doctrine
|
Neuron is basic unit of the nervous system, each w independent anatomy, development & biochemistry, is independent unit of metabolism, dynamically polarized, independent units of development, independent units of information processing
|
|
Dynamic polarization (1 way flow of info or signal)
|
In retina, signals which originate in the pigmented receptor cells always progress from dendrites - cell body - axon - terminals
|
|
Which part of the neuron is responsible for dynamic polarization?
|
Axon
|
|
Ramon y Cajal 1909 & 1911
|
Neurons in the cortex are units of information processing: AP & centralization reduces cost of cytoplasm
|
|
Electrical properties of neurons
|
Ion channels generate local electric signals on cell membrane
|
|
Propagated AP required
|
Voltage-activated ion channels
|
|
Evolution of voltage-gated channels
|
Came mostly from potassium channels
|
|
Synapses
|
Release & receptor (diverse): electrical or chemical
|
|
Sir Charles Scott Sherrington (1859-1952)
|
Nobel in Med w Edgar Adrian for reflexes in spinal cord as way of understanding function of neural circuits, coined term "synapses"
|
|
Law of reciprocal innervation
|
For every excitatory connection to a muscle, there is a corresponding inhibitory connection to an opposing muscle
|
|
Reflex
|
Cutaneous receptor stimulates leg flexes to withdraw, cutaneous afferent fiber from nociceptor to motor neuron to extensor muscle, opposite leg extends to support
|
|
Neurons are found in
|
all animals except sponges (porifera)
|
|
Polyp NS
|
Ectoderm, Gastroderm, mesoglea, gastrovascular cavity, tentacle, spermary with sperm, ovary with ovum, hydra bud
|
|
Nerve nets
|
Hydra and jellyfish (cnidaria)
|
|
Centralization
|
platyhelminthes: nerve cords, primitive brain vs. bilateral nerve cords
|
|
1700
|
Possible origin of NS-related genes, possible neurotransmission-related genes constituted the major category
|
|
540 MYA
|
Emergence of CNS: basis genes (neurotransmission, neural network, morphogenesis/differentiation, sensory system) -> divergence by gene loss, gene recruitment, gene duplication, horizontal gene transfer, mutation
|
|
Central Nervous system
|
Specific genes in each species: deuterostomia, ecdysozoa, lophotorochozoa
|
|
Neuroscience
|
multidisciplinary effort to understand how NS controls behavior: how we & other animals perceive, act, learn, remember
|
|
Nervous system complexity
|
Human NS has 100 bill neurons or nerve cells & thousands diff types neurons, 140 trillion synapses, many modified & regulated so function in multiple diff ways, unknown # neural circuits
|
|
Scientific method used to study brain & behavior
|
Empirical data collected by observations & measurement, hypotheses formulated on basis of reasonable interpretation of the data, hypotheses tested by experimentation & further observation
|
|
Neuron
|
Electrically excitable cells w highly varied elongated processes suitable for transmitting elec signals rapidly to other cells @ distance, responsive to elec & ligand-depend inputs from environment/other cells, recognized by elongate branching extensions from cell body
|
|
Elec signals travel @ great speed in neurons
|
Permitted our metazoan ancestors to get larger & larger but still move & respond quickly
|
|
Glial cells
|
Surround & support neurons but not directly involved in elec signalling. Provide: insulation, clean up after injury, guidance during development, regulation extracell chem, & formation blood/brain barrier
|
|
1954 using electron microscopes
|
Cell biologists confirmed that neurons were not fused & synapses mere contacts, not connections
|
|
The neuron is the basic unit of anatomy, development & biochem: with neuron doctrine anatomists could
|
define the NS in terms of types of cells rather than neural net postulated by reticularists
|
|
Neuron is the unit of metabolism
|
Like all cells, neurons control own biosynth & metabolic breakdown, reg gene expression, growth, transport intracell materials, transmembrane trafficking metabolites & other substances, initiating change in response to external cmpds & conditions: nucleus synth enzymes that control metab processes including uptake energy cmpds related to physiological activity of cell
|
|
Wallerian degeneration
|
Severing an axon leads to death of terminals
|
|
Nerve cell specialized intracell transport mech
|
Provide nutrients & metabolites to distal parts of axons
|
|
Support for dynamic polarization
|
Anatomical studies of retina & physiological studies of spinal cord by Sherrington (synapse is responsible)
|
|
Neurons are units of development
|
Neurons cannot divide because of shape but because they form connections w specific & distant targets, must first divide then differentiate & have a means for axon guidance to targets
|
|
Neurons are units of info processing
|
Communicate w other nerve cells via propagated AP
|
|
Ultra-microelectrodes
|
allowed researchers to make intracell recordings of APs: knowledge of complex neural circuits has to be built up from studies of individual cells & microelectrodes allow recording of spikes, synap potent, quantized synap events, & activity of ion channels
|
|
Ion channels arose
|
Early in evolution of life on earth (in bacteria) where used for regulating internal ion conc & pH
|
|
First synapse to arise in evolution likely
|
Electrical synapse: formed by connexins forming pore-like connections from one cell to another: cytoplasms fuse & charged ions (elec currents) & some small mlcs pass thru junctions in both directions
|
|
Chem synapses
|
one-way transmission - prob evolved in animals by first co-opting existing membrane bound receptors used for sensing small mlcs such as amino acids like glutamate
|
|
DNA sequence analysis of glutamate receptors
|
basic chem receptor in place in eukaryotes well before divergence of plants & animals - binding domain traces ancestry as far back as bacteria
|
|
Once glutamate receptor was established
|
animals evolved mechanisms to release near other cells carrying receptor & chem synapse became functional
|
|
Genes for receptor proteins were then duplicated & mutated to create families of similar receptors
|
Some chem synapses allowed pos ions to enter while others neg ions, causing synaptic inhibition - thru nat selection functional synapses applied to genetic specification of neural circuits
|