Lecture 3: Units of the Nervous System Flashcards
Describe function of soma/cell body
Process information, house cel, nucleus
Describe dendrites
Branching extensions from soma
Receive information from other nerves
# of dendrites = amount of incoming info
Describe dendritic spines
Protrusions from dendrites that are point of contact on axons
Describe axon
Long protrusion exiting soma which is covered in myelin, carrying nerve signal away
Describe myelin sheath
Made from glial cells, coating the axon in order to speed communication, nodes of Ranvier are not covered
Describe axon hillock
Point where axon leaves cell body
Describe axon collaterals
Point where axon branches out, allows messages to go to multiple terminals
Describe terminal button
End of axon collateral that stops close to dendritic spine of communicating neuron, but does not touch
Describe synapse
Junction between axon collateral of one neuron, and dendritic spine of next. It is a small space between terminal button and dendritic spine
List the three types of neurons
- Sensory - info to the brain
- Inter neurons - connect sensory and motor
- Motor - info from brain to muscles
What are two kinds of sensory neurons
Bipolar (in retina)
Somatosensory - skin, muscle
List three kinds of interneurons
Stellate - in thalamus, small and starlike
Pyramidal - in cortex, long axon and two sets of dendrites
Purkinje - in cerebellum, long axon, dendrites like tree
Describe a motor neuron
Extensive dendrites to collect lots of info from multiple sites, large cell body to process info, super long axon
List five types of glial cells and their functions
Ependymal - on walls of ventricles, produce CSF
Astrocyte - structural support, regulate BBB
Microglia - immune functions, engulf foreign bodies
Oligodendroglia - insulate axons in CNS
Schwann - insulate axons in PNS
How are damaged neurons repaired in the PNS?
When axon is cut, it dies. Microglia remove debris. Schwann cells shrink and divide making new cells along axons former path. Neuron sends out axon sprouts which find Schwann cells along path and create a new axon. Schwann cells envelope new axon, creating myelin
Describe cell membrane
Separates intracellular fluid from extra cellular via the phospholipid bilayer. The head of the bilayer is hydrophilic, while the tails are hydrophobic. It regulates movement of substances in and out of cell
Describe the nucleus
Contains genes which are inside chromosomes. Gene is to page as chromosome is to book. Chromosomes are made of DNA.
Describe the Endoplasmic Reticulum
Where RNA is synthesized. A strand of a gene is a template for a piece of mRNA, which leaves the nucleus and goes to the ER. Inside the ER, a ribosome reads the mRNA and can then decide what protein needs to be made.
Describe proteins
The product of a cell. First, it is a chain of amino acids, which form pleated sheets or helices. These then fold to form a protein, which can bind to other proteins to make more complex proteins.
How are proteins moved?
Packaged and labeled by Golgi bodies then moved along microtubules to final destination: incorporation into membrane, act as an enzyme, or excretion via exocytosis.
How do proteins behave when inserted into phospholipid bilayer?
Act as a channel for specific ions, act as gated channels for specific ions which open or close in response to a trigger, or as a pump which exchanges ions moving in opposite directions (sodium potassium pump)
