Week 1 Terms Flashcards
What is Convergence?
- when many pre-synaptic neurons converge on any single post synaptic neuron
- single cell receiving inputs from multiple sources
What is Divergence?
a single sell projecting/ sending out signals to multiple cells
On what day after conception does the neural tube of an embryo form?
~Day 23
What influences and interactions cause neuronal differentiation?
- Morphology
- Gene expression
- Neurotransmitters
- Axon projections & connections
What are the 2 Types (Directions) of Neuronal Migration?
1) Radial - moving OUT
2) Tangential - moving UP
What are 2 Methods of Migration?
1) Somal Translocation- extension develops in direction of migration
2) Glial-mediated - cells move along a radial-glial network
How many spinal nerves are there?
31
Through what structure do spinal nerves leave the vertebra?
through the corresponding intervertebral foramen
At which vertebra does the spinal cord end?
L1-L2
What is the cauda equina?
- The bunch of nerve roots at the lower end of the spinal cord
- cauda equina = horses tail
- located from ~L3
What parts of the brain are included in the Hindbrain?
1) Cerebellum
2) Pons
3) Medulla
What is the oldest part of the brain?
The Hindbrain
Where is the Diencephalon located and what are the 4 main parts?
- Location = top of brain stem
- Thalamus, Subthalamus, Hypothalamus, Epithalamus
What are the 4 Main Lobes of the Brain?
1) Frontal
2) Parietal
3) Temporal
4) Occipital
What are cortical ascending connections?
1) Somatosensory - from the Thalamus
2) Auditory -from Thalamus (inputs from cochlea)
3) Visual - from Thalamus (inputs from retina)
4) Smell - from Olfactory
5) Taste - from taste buds via thalamic nuclei
What is the most primative of all of our senses? (hint: and is the only sense that doesn’t go through the Thalamus?)
Smell
What are Descending Cortical Connects?
- Motor to spinal cord
- Motor to brain stem motor nuclei
- Motor to motor control centers
- to the Limbic system
What are Commissures?
pathways that connect one side of the brain with the other
they cross the midline to reach both hemispheres
What are Association Fibers?
a type of white matter tract that connects different areas in the same hemisphere
What are the 3 Major Classes of Neurons connecting Cortical Structures?
1) Association
2) Commisural
3) Projection
During development, cells of the nervous system differenciate into what 2 cell types:
1) Neurons - come in many forms, specialized based on function
2) Glia - support neurons
What are some of the Glial Subtypes?
- Ependymal cells
- Astrocytes
- Microglia
- Oligodendrocytes
What are Astrocytes and what are their functions?
Astrocytes are Glial Cells.
Functions include:
- scaffolding (for entire CNS)
- distribute nutrients from the blood supply to neurons
- function as glycogen reserve
- proliferate & migrate to area of injury (tissue repair)
- regulation of synaptic activity (clear out synapses as needed)
- new evidence suggest they can sense and respond to neuronal activity. they respond by raising intracellular calcium which can induce LTP.
What are the functions of Microglial cells?
- resident immune cells of brain
- clear debris –> can also degrade synapses (essential for pruning)
- recruit other cells to sites of damage
- aid in tissue repair
What are the fuctions of Oligodendrocytes?
- secrete lipid myelin to create myelin sheath
- myelin sheath increases speed of neuronal signalling
- provide metabollic support
How does Multiple Sclerosis prevent the brain from communicating with the body properly?
It causes degredation of the myelin sheath
What are Progenitor cells?
Descendants of stem cells that further differentiate to become a mature, specialized cell.
Describe Human Development (fertilization to 3 months):
Day 0= Fertilization Day 0-6= cleaves to form Blastocyte Day 7= Implantation of Blastocyte & formation of 2 layer disc. Day 14= Gastrulation Day 21= Neurulation Day 28-35= Tailbud Stage Day 28-56= Embryonic Period 3 Months to Birth = Fetal
Describe the process of Neurulation:
Occurs during Week 3
- Notochord starts/stimulates the process
- Ectoderm thickens to become neural plate
- Lateral edges of neural plate become elevated —> neural folds. Depressed region = neural groove.
- Neural folds fuse together and form neural tube (becomes brain & spinal cord).
- Neural crest forms above & becomes PNS.
Describe the Organization of the Nervous System
1) CNS
2) PNS
- Somatic
—Sensory
—Motor
- Autonomic
—Sympathetic
—Parasympathetic
What are 3 unique key features of Neurons?
1) High energy demand mainly from ATP pump
2) Need to transport cargo long distances for signaling or recycling
3) Limited capacity to generate new neurons
What is transcription?
Photocopying DNA into mRNA via RNA polymerase enzyme
What is translation?
Literal translation of the genetic code on the mRNA into a protein.
Read by ribosomes in cytoplasm of the cell.
What are Microglia and what are their functions?
Microglia are small glial cells of CNS.
They have a resting and active form.
Functions:
- look for dead & damaged areas
- when they sense inflammation from injury or infection they change to active form
- they secrete cytotoxic factors causing bacteria to turn into debris which they eat (phagocytosis)
What are Neuronal Substructures and their Functions?
1) Nucleus- stores genetic info
2) Endoasmic Reticulum- produces, sorts, and processes new proteins
3) Mitochondria- energy generator
4) Golgi Apparatus- additional processing & packaging of lipids & proteins
5) Lysosomes- contains digestive enzymes break down excess & worn out cell parts
6) Cell membrane- lipid bilateral
