PNS Exam 1
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What are the 3 major components of the PNS?
- 1. Cranial Nerves.
- 2. Ganglia.
- 3. Spinal Nerves.
True or false: Nuclei are groups of cell bodies in the PNS.
False. Ganglia are groups of cell bodies in the PNS.
Dorsal root ganglia are associated with which type of cell?
DRG = pseudounipolar.
Endoneurium: surrounds one fiber.
Perineurium: surrounds several fibers creating a fascicle.
Epineurium: surrounds groups of fascicles.
What is an a/k/a for rough ER?
- Nissel bodies: synthesizes proteins.
- The axon does not have Nissel Bodies, but dendrites can have Nissel bodies.
Which part of the neuron contains chromosomes?
- Double layered membrane with phospholipids & pores.
- Allows communication between inside & outside of nucleus via pores connecting to the ER.
Name the 3 functions of Golgi Bodies.
- 1. Storage.
- 2. Glycoprotein formation.
- 3. Lysosome/enzyme production.
What is the main function of mitochondria?
ATP (energy) production.
What are the 2 main function of cytoskeleton?
- 1. Forms the frame of the neuron.
- 2. Aids in transport.
- Microtubules: largest.
- Microfilaments: smaller (10).
- Microfibrils: smallest (3-7).
True or false? Axons are completely covered in Nissel Bodies.
- False: axons do not have any Nissel Bodies.
- Axons conduct action potentials.
Which process of a neuron is an extension of the cell body?
- Contains Nissel Bodies.
- Can have large branches where as axons do not.
True or false: larger axons conduct action potentials faster than smaller axons.
- Myelenated fibers conduct faster than unmyelenated fibers.
The synaptic cleft allows for diffused neurotransmitters to attach where?
- The post synaptic membrane.
- The synaptic cleft has enzymes to break down NT's.
- Anterograde: moving down the axon away from the cell body (soma).
- Retrograde: moving back up the axon toward the cell body (soma).
Histogenesis of neurons (from inside to outside):
- Ventricular zone: stem cell, pluripotent, begin development.
- Intermediate zone: differentiates into neuroblasts or glialblasts.
- Marginal zone: mature neurons.
Which zone of histogenesis is determined, but still immature?
The intermediate zone.
Name the 6 microgilal cells.
- 1. Astrocytes: injury response, mechanical & metabolic support.
- 2. Oligodendrocytes: forms myelin in the CNS.
- 3. Ependymal cells: CSF production.
- 4. Microglia: phagocytosis (immunity of the CNS).
- 5. Schwann cells: myelenation in the PNS, axonal regrowth, & metabolism.
- 6. Satellite cells: flattened schwann cell, similar to astrocytes.
Which migroglial cell is responsible for forming scar tissue in damaged brain areas?
What is the number 1 type of brain cancer?
What is the most common form of gliomas?
- Oligodendrogliomas: very rare.
Which dermatome innervates the nipple?
- T10: umbilicus.
- L5: big toe.
- S1: heel.
- S2: back of thigh.
What type of receptors respond to a stimulus?
What is the name for the territory from which a sensory unit can be excited?
- Receptive field.
- Single neuron.
- Responds to one sensory unit.
- More sensitive areas are smaller.
The transformation of a stimulus into an electical signal is described by what term?
- Sensory transduction.
- Discriminative touch & kinesthetic stimulation.
- Carried by myelenated type A axons.
True or false: myelenated type C axons are responsible for carrying pain, touch, & temperature sensations.
False: unmyelenated type C axons are responsible for pain, touch, & temp sensations.
Rapidly adapting responses are associated with which type of receptors?
- Responds quickly & maximally.
- Will stop responding even when the stimulus continues.
- There is a refractory period before it will respond again.
Slowly adapting responses are assocated with which type of receptors?
- Will continue to respons to a stimulus without a refractory period.
Name the 3 types of non-encapsulated receptors.
- 1. Free nerve endings: pain & temp.
- 2. Follicular: touch.
- 3. Merkel cells: pressure.
Name the 3 types of encapsulated receptors.
- 1. Meissner's: light touch, type A.
- 2. Ruffini's: shearing (drag) forces.
- 3. Pacinian: vibration.
Mnemonic for remembering which receptors are slow adaptors: MR Slow.
Rapid = PMF.
- Merkel cells (non-encapsulated).
Reflexes are a predictable response to a stimulus which will happen every time.
Sensory limb & motor limb.
What is the term used to describe a stem fiber & all of its endings?
What is the functional unit of the motor system?
The motor unit.
Name at least 2 characteristics associated with extrafusal muscle fibers.
Intrafusal (muscle spindles) = gamma motor neurons = proprioception.
- 1. Alpha neurons (via grey matter).
- 2. Results in movement of skeletal muscles (motor unit).
- 3. Gamma motor neuron -> muscle spindle.
- 4. The more neurons that are involved, the more intricate the movement.
True or false: golgi tendon organs are found at the muscle-tendon junction.
What are the 4 functions of golgi tendon organs?
- 1. Measuring the force of contractions (strong or weak).
- 2. Autogenic inhibition: self control of inhibition.
- 3. Protecting muscles from excessive contraction.
- 4. Fine adjustments in the force of muscle contractions.
Freely ending unmyelenated nerve fibers are responsible for pain & excitatory reflexes. Where are they found?
- 1. Ligaments.
- 2. Capsules.
- 3. Menisci.
What is an a/k/a for the flexor reflex?
- Withdrawal reflex.
- Involves the whole limb.
- Thus several spinal segments.
- Has crossed effects: simultaneous & opposite pattern of activity in the contralateral limb.
Which lobe integrates sensory information from joints, muscles, & skin?
The parietal lobe.
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