neurons, synapses and signaling Flashcards
What are the 5 properties of neurons?
1) receive conducting and then transmitting neurons
2) excitable (we can elicit a response)
3)longevity (function for the lifetime of an organism)
4) amitotic (neurons are located in Go), In some areas with stem cells, they can be replenished
5)high metabolic rate (needs high o2, high gluc to produce a lot of ATP)
parts of a neuron
Cell body/soma: contains nucleus, organelles, have extensive rough ER
mature neurons lack centrioles
Dendrites: extensions on the cell body that receive inputs, have high surface area
Axons hilock: base of hte axon (connects cell body and axon). Conducts signals, axons have cytoplasm
movement of substances within a neuron (anteriograde vs retrograde)
anteriograde: away from the cell body (mitochondria, cystoskeletal elements, vesicles that renew plasma membrane, enzymes)
retrograde: towards the cell body (organelles that need to be broken down)
intrracellular communications allows cell body to know status of axon termionals
Some signals can activate nuclear genes to promote growth
[Neuroglia - CNS] What are Astrocytes? How abundant are they? What do they do (4 things)? What is the blood brain barrier permeable eto
Most abundant, have
1) perivascular feet that contact the blood capillaries. (This stimulates them to form a tight protective seal - blood brain barrier).
2) monitor neuron activity which leads to dilation and constriction of blood vessels
3) regulate composition of tissue fluids by uptaking H+ and neurotransmitters. Prevents things from reaching a high concentration.
4) scar tissue forms where damaged neuron was
Blood brain barries forces things leaving the blood to pass through the cells and not in between so that theres more regulation
permeable to glucose, gases, and things like alcohol, caffeine nicotine. Impermeable to chemotherapies
[Neuroglia - CNS] ependymal cells
ciliated and (like central cavities of brain and spinal cord) form a permeable barrier between cerebrospinal fluid that fills these spaces
cilia of ependymal cells circulates this fluid
what does cerebrospinal fluid do? (3 things)
1) Protects brain from injury
2) offers chemical stability
3) increases buoyancy which helps cushion brain and spinal cord.
[Neuroglia - CNS] Oligodendrocytes
Insulate neural fibers with a covering called a myelin sheet
(helps propagate nerve signals along the fiber. Think saltatory conduction)
[Neuroglia - CNS] Microglia. WHat are they?
They are small macrophages that develop from monocytes
1) Wander through CNS and put out projections to sense for things that shouldn’t be there
2) we expect to see increase microglia in areas of infection or trauma. Microglia are important bc cells of immune system have limited access to CNS.
[Neuroglia - PNS] Satellite
regulates chemical environment (O2, Co2, nutrients and neurotransmitters)