COMPREHENSIVE EXAM PREP, PRACTICE
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,Anterograde axoplasmic transport toward the front; accomplished by molecules of a protein called kinesin
- kinesin attach to the item being transported down the axon and "walks" down a
microtubule carrying the cargo to its destination
- requires energy supplied by ATP (mitochondria)
- very fast (up to 500 mm/day)
retrograde axoplasmic transport (toward the back); carries cargo from the terminal buttons to the soma using dynein
(another protein)
half as fast as anterograde
nucleus contains nucleolus sand chromosomes
nucleolus produces ribosomes, which is involved in protein synthesis
mitochrondria - responsible for extracting energy from nutrients
- produce ATP, which cells use for energy
- contain their own DNA
- likely originally an infection of the larger cell
Endoplasmic Reticulum - layers of membrane in cytoplasm
- rough: contains ribsomes (synthesis of proteins)
- smooth: synthesis of lipids
ex) Golgi apparatus: produce membranes (packaging that release hormones or
neurotransmitters)
lysosomes organelle that breaks down waste products
ribosomes -cytoplasmic structure made of protein
- involved in attaching amino acids (translation of mRNA) for the generation of proteins
,Chromosomes -strand of DNA, carries genetic information
- 22 pairs autosomes, one sex (XY)
Gene -functional unit of chromosome that directs specific protein synthesis
- codons: cytosine, guanine, thymine, adenine
mRNA copy of genetic information to make a protein (at ribosome)
DNA transcription to translation -DNA genes gets unraveled by RNA polymerase
- free base pairs (adenine, uracil, guanine, and cytosine) match the DNA template
(cytosine, guanine, thymine, adenine) to make mRNA (transcription) which then travels out
of the nucleus and into the cytoplasm
- ribosomes read the code in the mRNA (translation) to generate a chain of amino acids,
which will build a specific protein, such as neurotransmitter receptor
Blood Brain Barrier - in most of the body, the capillaries have small gaps that permit the free exchange of
most substances between the blood and the fluid outside the capillaries
- not in the CNS--> the walls of the capillaries in the brain constitute the blood-brain
barrier
- substances must be actively transported through the capillary walls by special proteins
- because the brain depends on a delicate balance between substances within neurons
and those in the extracellular fluid that surrounds them, the BBB is key to allowing our
brains to function
- it prevents dangerous chemicals from reaching brain
- the BBB is not uniform throughout the CNS and some areas are more permeable: area
postrema is area of brain that controls vomiting. Neurons are able to detect the presence
of toxic substances in the blood and initiate vomiting
, Ion movement mechanisms active transport (requires ATP): sodium-potassium pump
concentration gradient- passive
voltage gradient- passive
action potential strength strength of a stimulus is represented by the rate of firing of an axon: faster firing leads to
stronger stimulus (more painful)
size of each action potential is always constant
saltatory conduction more axons are myelinated
ions cannot cross the membrane in myelinated sections
disturbance in the ionic field gets smaller as it passes under a section of myelin but is still
strong enough to generate a new action potential on the other side
- decremental conduction: decreases in the size of the disturbance
AP gets retriggered at each node of Ranvier
the transmission of this message, hopping from node to node--> saltatory conduction
saltatory conduction allows the cell to function more efficiently because removal of
sodium is energy consuming (sodium-potassium pump) and sodium cannot enter under
myelin
saltatory conduction much faster because the AP needs to only be retriggered at every
node rather than everywhere