9.15 Notes Flashcards
Radial glia
Helps neurons go where they’re supposed to go during development
Three types of macroglia
Astrocytes, Schwann cells, ogliodendrocyte
Astrocytes
Star-shaped macroglia; very involved in stopping neurotransmission from occurring; places part of their cell (end feet) on a capillary; sends neurotransmitters to the blood; makes up the blood-brain barrier
Schwann cells
Macroglia located in the PNS; makes up myelin
Oligodendrocyte
Macroglia located in the CNS; relatively small; makes up myelin
Parkinson’s disease
Death of neurons that produce dopamine
Blood-brain barrier
Semi permeable barrier between the blood and brain; allows some materials to cross, that prevents others; somethings can cross with help
Things that can cross the blood-brain barrier easily
Oxygen and carbon dioxide
Things that can cross the blood-brain barrier with active transportation
Glucose
Fat-soluble molecules
Can pass into the blood brain barrier her, but this has negative effects; acts directly on the brain; nicotine, alcohol, heroin, and barbiturates
Where is the blood-brain barrier particularly weak?
In the circumventricular organs; Pituitary gland (needs to be able to monitor the blood for hormone levels) and area postrema (the vomiting center; Can monitor the blood for toxins)
Neuron membrane
Semi permeable; made of a lipid bilayer and protein molecules that are embedded in the lipid bilayer
When a neuron is at rest, is the inside more negative or positive than the outside?
Negative
Electrical gradient
The difference in the electrical charge between the inside and outside of the cell
At rest, where are each of the molecules?
Inside: Na+, CL+, and negatively-charged proteins
Outside: K+
K+
Potassium ion
Na+
Sodium ion
CL-
Chloride ion
Ca++
Calcium ion
Concentration gradient
Absolute number of ions; difference of the ions on the inside versus outside
Sodium-potassium pump
Enzyme that actively forces 3 sodium ions outside of the cell and pulls in 2 potassium ions; uses 1 ATP
Action potential
An explosion of electrical energy caused by a depolarizing current
Depolarize
To become more positive; to move towards zero
Threshold
-55 millivolts; based on the all-or-none principle; determined by whether the neuron fires or not; the action potential does not change
Hyperpolarization
The cell is now more negative after firing than it was at rest; sodium-potassium pump fixes this
Propagation of action potential
The movement of the firing down the axon
Nodes of Ranvier
The junctions between myelin; where the action potential occurs
Salutatory conjunction
The jumping of the action potential from node to node, which makes the action potential move faster in myelinated neurons
Refractory period
When a neuron can no longer fire again after it was fired; can be either absolute or relative
Absolutely refractory period
Sodium channels are closed; no action potential can occur whatsoever
Relative refractory period
Potassium channels are still open; a lot more sodium has to come in, so a stimulus would have to be very strong for firing to occur
Otto Lowei
Electrically stimulated a frogs heart to beat very quickly; took fluid from the heart and put it in another frog’s heart, which started beating faster; prove that there’s a chemical part of communication
Microglia
Highly involved in caring for neurons; remove dead neurons and waste; involve the neurotransmission; involved in the uptake of neurotransmitters
