Nervous System Overview Flashcards
Ganglion (pl: ganglia)
Bundle of neural cell bodies found in the PNS
Nucleus
Collection of cell bodies in CNS
Nerve
A bundle of neuronal axons
Afferent is interchangeable with
Sensory
Efferent is interchangeable with
Motor
Sensory is interchangeable with
afferent
Motor is interchangeable with
Efferent
Anatomical direction of the brain
Rostral (anterior) - towards nose
Caudal (posterior)- Towards tail
Dorsal- top
ventral- bottom
Think: horse
What do afferent (sensory) neurons do
Receive and transmit information from the enviroment to the CNS
What do efferent (motor) neurons do?
Transit information from the CNS to the PNS to elicit a response
Main parts of the CNS and PNS
CNS: Brain and spinal cord
PNS: Cranial neres (except not CN 1 or 2), spinal nerves (motor/efferent), peripheral nerves(mixture of motor, sensory and autonomic), and neuromuscular junctions.
Divisions of the PNS
Somatic: Conscious/voluntary
Autonomic: Involuntary
- Sympathetic (fight or flight)
- Parasympathetic (rest and digest)
Effector in somatic (voluntary of PNS) nervous system
Skeletal mucles
Effectors of the involuntary/autonomic part of the PNS
Smooth muscles, glands, cardiac, adipocytes
Glial cells/neuroglia
Support neurons and their functions (CNS)
- Astrocytes
- Microglia
- ependymal
- oligodendrocytes
What cells in the PNS produce myelin
Schwann
What cells in the CNS produce myelin
Oligodendrocytes
Another name for body of a neuron
perikaryon, soma
Neurite
Dendrite + axon
Axon transport (2 main types)
Anterograde- moving from soma to axon terminal. Traveling in the same direction as the signal.
- Rapid anterograde: Rapid. Quick. Fed ex. Utilizes protein kinesin, which transports secretory vesicles likely filled with neurotransmitter from the soma and/or mitochondria by the microtubules. Travels 2-4 cm a day. Requires ATP.
- Slow transport. Another type of anterograde, but moves passively through the axon’s plasma. Slow, snailmail. No ATP or energy required.
Retrograde: Moving from axon terminal to soma. Travels in the oppsite direction of the signal. Dynein is the transport protein that carries worn-out organnels on microtubules. Requires ATP.
Which is more common- chemical or electrical synapse
Chemical synapse is more common. Electrical synapses commonly occur in the brain.
3 types of neurons
Classification based on the number of neurites (axons and dendrites) a cell has
- Multipolar neuron:
- Numerous dendrites
- Most common type in the CNS
- Motor, integrator, intermediate - Bipolar neuron:
- Single dendrite from ell body.
- Sensory receptors
- Sight, smell and vestiular - Pseudo-unipolar neuron:
- Single dendrite/axon arises from common stem off body cell
- Most common type in PNS
- Primary sensory neuron
What type of neuron is most common in the CNS
Multipolar neuron
What type of neuron is most common in the PNS
Pseudo-unipolar (unipolar) neuron
Neuron classifiations based on size
- Golgi type 1:
Long axons (vast majority of neurons are golgi type 1. They can either be sensory/afferent or motor/efferent).
- Golgi type 2:
Very short axons. Ex: interneurons.
Reflex arc
Receptor (organ) –> afferent/sensory neuron –> interneuron —> efferent/motor neuron —> effector organ (skeletal muscle for somatic or gland/smooth muscle for autonomic/involuntary NS)
Astrocytes
Neuroglia found in the CNS. The most abundant and largest glial cell.
Many functions include structural support for neurons, metabolic support (uptake excess K+ and renew neurotransmitters), some contribution to the blood brain barrier, and promote myelination activity of oligodendryocytes.
Can also modulate local blood flow by it’s foot process coming in contact with gap junctions
Micoglia
2nd most common in the CNS.
Derrived from mesenchyme.
Immunological function- phagocytic role, response to tissue damange, inflammation and infection.
(Schwann cells in the PNS have a phagocytic role too)
Ependymal cells
Epithelial type cells with tight junctions and typically ciliated. Line ventricles and central canal of spinal cord. Aid in production and moement of CSF.
___ is made up of modified ependymal cells
Choroid plexus. Where CSF is made.
Oligodendrocytes
Myelination of the CNS. It wraps around multiple axons many times using extensions from one cell body. Very efficient.
Schwann cells
Myelinating cells found in the PNS. It’s cell body can wrap around a portion of an axon multiple times, but thats it. It only comes in contact with one axon.
Exception: schwann cells can “encapsulate” many tiny tiny axons. However, this is technaiicaly not a form of myelination, since the myelin doesn’t “wrap,” it only encapsulates.
Technically not a glial cell, since it isn’t found in the CNS.
White matter
Myelinated axons in the CNS
Grey matter
Cell bodies (perikaryon) in the CNS and glial cells.
Where is white and grey matter located at in the brain? In the spinal cord?
Brain- white in center, grey on outside.
Spinal cord- Grey in center, white on outside.
Basic nerve structure from smallest to largest
Fibers/neurons wraped by endoneurium–> Fasicles wraped by perineurium–> nerves wraped by epineurium
Within the nerve, you have the fasicle bundles, fat, blood vessels, and neuroglia.
Endo, peri, and epineurium are all types of connective tissues.
Nissle bodies
Rough ER in the neuron. It will degrade if neuron is damanged. Causes neucleus to be pushed to the side. If the injury is mild, the neuron can recover. If not, the neuron will dissinigrate/
Meninges and examples
Are dural deflections (dura mater)
- Falx cerebelli (cerebral falx)
- Tentorium cerebelli
Hematomas
Area of blood that collects outside of larger blood vessels.
A subdural hemorrhge (ruptured vein) is deep to dura and will spread slowly. (bleeding is between arachnoid space and dura mater)
An epidural hemorrhage is arterial bleeding that will spread quick because pressure in the artery is so high. (bleeding is between dura mater and skull)
Weakest part of the skull
Pterion. Where 4 bones on the skull come together, Traction and the middle meningial artery is there.
if you shatter the pterion, the middle meningial artery splits and causes an epidural. needs to be drained or too much pressure will be put on the brain and cause death.
