ch1 Flashcards
Glial cell
Glia are smaller more numerous than neurons.
Types of glia cells
Astrocytes Oligodendrocyte Schwann cell Microglial cells Radial glial cells
Astrocyte
Astrocytes wrap around the presynaptic terminals of a group of functionally related axons.
By surrounding a synapse between neurons, an astrocyte shields it from chemicals circulating in the surround.
By taking up ions released by axons and then release long them back, it helps synchronize the activity of the axons, enable them to send messages in waves.
Guide the formation and elimination of synapses.
They remove waste material created when neurons die and control the amount of blood flow to each brain area.
During periods of heightened activity in some brain area, it dilate the blood vessels to bring more nutrient into that area.
Oligodendrocyte
Oligodendrocyte in brain and spinal cord build myelin sheaths that surround and insulate certain vertebrate axons. It also supply an axon with nutrients necessary for its functioning.
Schwann cell
Schwann cells in periphery of the body build myelin sheaths that surround and insulate certain vertebrate axons. It also supply an axon with nutrients necessary for its functioning.
Microglia
Microfilm act as part of the immune system, removing waste material, viruses, and fungi from the brain. They proliferate after brain damage and in most brain diseases. They also contribute to learning by removing the weakest synapses.
Radial glia
Radial glia guide the migration of neurons and their axons and dendrites during embryonic development. When embryonic all development finishes, most radial glia differentiate into neurons, and smaller number differentiate into astrocyte and oligodendrocyte.
Membrane
Plasma membrane
Most chemicals cannot cross the membrane, but protein channel in the the membrane permit a controlled flow of water, oxygen, sodium, potassium, calcium, chloride, and other important chemicals.
Nucleus
The structure that contains the chromosomes.
Mitochondria
Perform metabolic activities
It require fuel and oxygen.
Ribosome
The sites that the cells synthesizes new protein molecules. Proteins provide building materials for the cell and facilitate chemical reactions.
Some float freely within the cell, but others are attached to the endoplasmic reticulum.
Endoplasmic reticulum
A network of thin tubes that transport newly synthesized proteins to other locations.
Golgi Apparatus
Wrap or package substances in vesicles for transport to axon terminal
Only in neuron and axon
Microtubules
Provide intercellular transport
Only in neuron and axon
Multipolar
Most common
One axon and many dendrites.
Unipolar neuron
Rare in humans, found in the mesencephalic nucleus of the 5th cranial nerve.
Bipolar neuron
One axon and one dendrite. Are found in cochlear and vestibular ganglia, retina and olfactory epithelium
Sensory
Afferent
Specialized at one end to be highly sensitive to a particular type or stimulation
Bring information into a structure
Motor
Efferent
It’s soma in the spinal cord, receives excitation through its dendrites and conducts impulses along its axon to a muscle
Carries information away from a structure
Intrinsic neuron
If a cell’s dendrites and axon are entirely contained with a dingle structure, the cell is an interneuron or intrinsic neuron of that structure.
Dendrites
Dendrites are branching fibers that get narrower near their end. The dendrites’ surface is linked with specialized synaptic receptors, at which the dent rite receives information from other neurons. The greater the surface area of a dent rite, the more information it can receive.
Dendritic Spines
Many dendrites contain dendritic spines, short out growths that increase the surface area available for synapses.
Soma
Cell body
Nucleus, ribosomes, mitochondria
Most of a neuron’s metabolic work occurs here.
Like dendrites, soma is covers with synapses on its surface in many neurons.
Axon
The axon conveys an impulse toward other neurons, an organ, or a muscle.
It can range up to more than a meter in length.
Myelin sheath
Myelin is a fatty substance that surrounds the axon of some nerve cells, forming a electrically insulating layer.
Nodes of ranvier
A gap in the myelin sheath of a neuron.
Presynaptic terminals
End bulb or bouton
The end of each axon
Neurotransmitter is packaged inside small vesicles in presynaptic terminal s.
Nourishment of neuron
Neuron depend almost entirely on glucose. Because the metabolic pathway that uses glucose requires oxygen, neurons need a steady supply of oxygen. Although the brain constitutes only about 2 percent of the body’s weight, it uses about 20percent of its oxygen.
Glucose is the only nutrient that crosses the blood- brain barrier in large quantities.
To use glucose the body need B1, thiamine.
Prolonged thiamine deficiency, common in chronic alcoholism.
Korsakoff’ syndrome, severe memory impairment.
Blood- Brain barrier
It depends on the endothelial cells that form the walls of capillaries. They block viruses, bacteria, and other harmful passage from passage
Oxygen, carbon dioxide cross freely. Water cross through special protein channels. Molecules that dissolve in the fats of the membrane cross easily.
Active vs passive transport
While active transport needs energy and work, passive transport does not.
Actively transport into the brain include glucose, amino acids ( building blocks of proteins), purines, choline, a few vitamins, iron, and certain hormones.
