Chapter 1 Flashcards
What are the 4 glial cells?
Astrocytes
Schwann cells
Microglia
Radial glia
What was the work of Nobel prize winner Santiago Ramon y Cajal?
He proved the brain consists of individual cells, which are now called neurons
What structure is responsible for synthesizing protein molecules?
Ribosomes
All neurons have __
a soma (cell body)
What is the dendrite’s surface lined with?
Specialized synaptic receptors, where the dendrite receives info from other receptors
What increases the surface that’s available for synapses?
Dendritic spines
What axons do not have myelin sheaths?
Invertebrate axons
What is the end of each axon branch called & what is the function?
A presynaptic terminal, where the axon releases its chemicals
Every sensory neuron is
Afferent
Every motor neuron is
Efferent
Where do glia cells outnumber neurons?
The cerebral cortex
What type of glial cell takes up the ions & transmitters released by axons & synchronizes closely related neurons to enable their axons to send messages in waves
Astrocytes
What type of glial cell is responsible for dilating blood vessels & generating rhythms, like your heartbeat, and is important for learning & memory?
Astrocytes
What type of glial cells multiply & act as a part of the immune system after brain damage to remove dead or dying neurons?
Microglia
What type of glial cells produce myelin, which is necessary for saltatory conduction in the PNS?
Schwann cells
What type of glial cells produce myelin in the CNS?
Oligodendrocytes
What type of glial cells guide the migration of neurons & their axons/dendrites during embryonic development & can differentiate into neurons?
Radial glia
What type of axon brings information to a structure?
Afferent axon
What type of axon carries information away from a structure?
Efferent axon
What are gaps/interruptions in myelin sheath called?
Nodes of Ranvier
What type of neuron receives excitation through its dendrites, conducts impulses along its axon to a muscle, and has its soma located in the spinal cord?
Motor neuron
What type of neuron is specialized at one end to be highly sensitive to a particular type of stimulation?
Sensory neuron
What is a network of thin tubes that transports newly synthesized proteins to other locations that some ribosomes are attached to?
Endoplasmic reticulum
What is the structure that contains chromosomes
Nucleus
What receives information & transmits it to other cells?
Neurons
What is an axon?
A thin fiber that conveys an impulse toward other neurons, an organ, or a muscle.
How fast a drug takes effect depends on what?
How readily it dissolves in fats & crosses the blood-brain barrier
What is a protein-mediated process that expends energy to pump chemicals from the blood into the brain?
Active transport
Which chemicals cross the blood-brain barrier by active transport?
Glucose & amino acids
Why is chemotherapy difficult to treat?
Most chemotherapy drugs fail to cross the blood-brain barrier
What does the body need to use glucose?
Thiamine, also known as Vitamin B1.
What does prolonged thiamine deficiency lead to?
Neuron death & Korsakoff’s Syndrome, which is marked by severe memory impairments
What are the major parts of a neuron?
Cell body (Soma), dendrites, an axon with branches, and presynaptic terminals
What can cross the blood-brain barrier freely?
Lipid/fat soluble molecules, like barbiturate drugs, water, oxygen, carbon dioxide, & certain hormones (insulin)
Neurons rely heavy on __, which is the only nutrient that crosses the blood-brain barrier in large quantities
Glucose
What is the brain’s main energy source?
Glucose
What does the membrane maintain while at rest?
An electrical gradient, also known as polarization
A difference in voltage is called
Resting potential
What does the membrane have that allows some chemicals to pass more freely than others?
Selective permeability
What transports sodium ions out of the cell, while drawing potassium cells into it?
Sodium-potassium pump
What type of transport requires energy?’
Active transport
What makes the sodium-potassium pump effective?
The selective permeability of the membrane, preventing sodium ions that were pumped out from leaking back in, therefore increasing the electrical gradient across the membrane
What makes sodium more concentrated on the outside than the inside, so sodium is more likely to enter the cell?
Concentration gradient
What prepares the neuron to rapidly respond?
Resting potential
Messages sent by axons are called
Action potentials
What is it called when the negative charge inside a neuron is increased
Hyperpolarization
What is it called when you reduce polarization toward zero & sodium and potassium pumps open?
Depolarization
What happens when an action potential reaches the threshold of excitation?
Sodium channels open
What law states that the amplitude & velocity of an action potential are independent of the intensity of the stimulus that initiated it, & puts constraints on how an axon can send messages?
All-or-none law
What happens at the peak of an action potential?
Sodium channels close
Immediately after an action potential, the membrane enters a __, during which it’s resistant to starting another action potential
Refractory period
What type of neurons have no axon & convey information over short distances?
Local neurons
When the membrane is at rest, where are the sodium & potassium ions?
Sodium ions are concentrated outside, potassium ions are concentrated inside
True or false: People only use some of their brain, but not all of it
False
What is a bundle of axons traveling together called?
Nerve
