Chapter 1 Flashcards
What fuels the NS
Glucose
Cells of the NS
Membrane Nucleus Mitochondria Ribosomes Endoplasmic reticulum
Membrane
separates the inside of the cell from the outside environment
Nucleus
contains the chromosomes
Mitochondrion
performs metabolic activities and provides energy that the cells requires
Ribosomes
sites at which the cell synthesizes new protein molecules
Endoplasmic reticulum
network of thin tubes that transports newly synthesized proteins to their location
A motor neuron
Has its soma in the spinal cord
Receives excitation from other neurons
A sensory neuron
specialized at one end to be highly sensitive to a particular type of stimulation (touch, light, sound, etc.)
Components of all Neurons
Dendrites
Soma/cell body
Axon
Presynaptic terminals
Dendrites
Branching fibers with a surface lined with synaptic receptors responsible for bringing information into the neuron
Cell Body/Soma
Contains the nucleus, mitochondria, and ribosomes
Responsible for the metabolic work of the neuron
Axons
Thin fiber of a neuron responsible for transmitting nerve impulses toward other neurons, organs, or muscles
Presynaptic terminals at the end points of an axon release chemicals to communicate with other neurons
Presynaptic terminals
at the end points of an axon release chemicals to communicate with other neurons
Afferent axon
bringing information into a structure
Efferent axon
carrying information away from a structure
Types of Glia
Astrocytes
Microglia
Oligodendrocytes (CNS) and Schwann cells (PNS)
Radial glia
Astrocytes
Astrocytes pass chemicals back and forth between neurons and blood and among neighboring neurons
Microglia
Remove waste material, viruses, and fungi from the brain
Oligodendrocytes (CNS) and Schwann cells (PNS)
build the myelin sheath that surrounds and insulates certain vertebrate axons
Radial glia
Guide the migration of neurons and the growth of their axons and dendrites during embryonic development
After embryonic development , most turn into neurons, some turn into astrocytes and oligopolistic
Oligodendrocytes
produce myelin sheaths
Schwann cells have similar functions
Myelin
an insulating material composed of fats and proteins
Santiago Ramón y Cajal
first to demonstrate that the individual cells comprising the nervous system remained separate and did not merge into each other
Variations Among Neurons
function is closely related to the shape of a neuron
The Blood-Brain Barrier
Advantage- mechanism that surrounds the brain and blocks most chemicals from entering
Disadvantage- but can pose a difficulty in allowing chemicals such as chemotherapy for brain cancer to pass the barrier
Active Transport
The protein-mediated process that expends energy to pump chemicals from the blood into the brain
The Nerve Impulse
The electrical message that is transmitted down the axon of a neuron
Does not travel directly down the axon, but is regenerated at points along the axon so that it is not weakened
When the membrane is at rest
Sodium channels are closed
Potassium channels are partially closed allowing the slow passage of potassium
sodium-potassium pump
Continually pumps three sodium ions out of the cells while drawing two potassium ions into the cell
Helps to maintain the electrical
Concentration of ions
Sodium ions are more concentrated outside the neuron, and potassium ions more concentrated inside
Depolarization
causes the membrane potential to become less negative
Hyperpolarization
causes the membrane potential to become more negative
The Movement of Sodium and Potassium
After an action potential occurs, sodium channels are quickly closed
The neuron is returned to its resting state by the opening of potassium channels
Local Neurons
Have short axons, exchange information with only close neighbors, and do not produce action potentials
MYTH
Only 10 percent of neurons are active at any given moment
TRUTH
You use all of your brain, even at times when you might not be using it very well
Ionotropic effects
-occurs very quickly, relies on glutamate, neurotransmitter attaches to receptors and opens ion channels.
metatropic effects
-neurotransmitters attach to a receptor and start a sequence of metabolic reactions.
which is faster ionotropic or metatropic?
ionotropic.
What is a neurotransmitter?
a chemical that travels accros the synapse to communicate.
where are neurotransmitters they made?
Neurotransmitters are made in neurons.
what are the building blocks of neurotransmitters?
protein found in diet
what are neuropeptides?
also known as neuromodulators, is a type of neurotransmitter.
what are hormones?
chemicals secreted by endocrine glands or cells that enter the blood stream and cause changes.
In what way is a neuropeptide intermediate between neurotransmitters and hormones?
neuropeptides diffuse more widely than other neurotransmitters but less than a hormone
