Week 5 - Nerves Flashcards
Where do neurons receive impulses?
Dendrites and cell body (perikaryon)
Where do neurons intergrate the information given to them?
On their axon hillock
What are the 3 main areas on electron microscope of synaptic junction?
What are the properties of motor neurons?
- Large perikarya
- Nissl bodies (dark spots) in cytoplasm
- Large nuclei
- Innervate muscle cells directly
What is the function of the axon hillock?
Site of action potential generation
What is Nissl substance?
Rough endoplasmic reticulum
What are the ‘rails’ and ‘vehicles’ of neurons?
Rails = microtubuli and neurofilaments
Vehicles = kinesin and dynein
What are neurons completely dependent on?
Glial cells
What are the proeprties of astrocytes and where are they found?
- Cover all surface of neuron not occupied by synapse or myelin
- Master supporters of CNS
- Take up nutrients from capillaries and provide to neurons (forms blood-brain barrier)
- Form seal on CNS surface
Glial cells
What are the properties of oligodendrocytes and where are they found?
- Make myelin
- Allow saltatory conduction through myelination of neurons
Glial cells
What are the properties of microglial cells?
- Function in immune system of CNS
- Use cytokines to attract other defense cells
- Can phagocytose and act as local APCs
- Role in maintenance and remodelling of CNS
What are the properties of microglia cell nuclei?
- Elongated
- Dark
- No clear lining
- Sometimes granulated
What are the proeprties of astrocyte nuclei?
- Larger
- Oval shaped
- Heterochromatin granules
- No visible cytoplasm
What are the proeprties of oligodendrocyte nuclei?
- Round
- Dark
- Sometimes slightly granulated
What’s the difference between wite and grey matter?
White = + nerve connections with + myselinsation
Grey = clusters of neurons
What are clusters of PNS perikarya called?
Ganglia
What are clusters of CNS perikarya called?
Nuclei
What is an anatomical nerve?
Collection of axons/dendrites bundled and ensheathed into fasicles, held together by connective tissue
What is the epineurium?
Partially dense, collagenous connective tissue
What is the perineurium?
- Sheath with flat cells with collagen fibres between them
- Bund;es axons into fasicles, forming a seal
What is the endoneurium?
Loose connective tissue between axons/dendrites within fasicles
What is the role of satellite cells?
Support cells for PNS ganglia
What is the intracellular calcium ion concentration at rest?
0.1uM
What happens to airway smooth muscle when extracellular K+ ion concentration is elevated?
- 4-fold increase in intracellular Ca2+ ion concentration
- Muscle contraction
What is the role of carbachol in airway contraction?
- Is an agonist at G protein-coupled muscarinic receptors
- Produces airway smooth muscle contraction
- Lower calcium ion rise
What can block voltage-gated potassium channels?
TEA and 4-AP
What does dorsal and ventral mean?
Dorsal = posterior
Ventral = anterior
How many vertebrae are there in each section of the spine?
- Cervical = 7
- Thoracic = 12
- Lumbar = 5
- Sacral = 5
- Coccygeal = 3-5
What are the proeprties of a lumbar puncture?
- Locate L4 iliac crest
- Isert between L4-5
- Into subarachnoid space
What are the ascending pathways of white matter?
What are the descending pathways of white matter?
What is the functino of the rubrospinal pathway?
Large muscles of limbs
What is the function of the corticospinal pathway of white matter?
Controls muscles of limbs
What is the function of reticulospinal pathway of white matter?
Motor coordination, muscle tone, autonomic functions and pain
What is the function of the vestibulospinal pathway of white matter?
Posture and balance
What is the function of the tectospinal pathway of white matter?
Head and eye movement
What is a spinal motor neuron?
Lower motor neuron
What is a motor unit?
Number of muscle fibres innervated by a single spinal aloha motor neuron
What is the function of upper motor neurons?
Innervate spinal motor nberons, from brain
What is the funciton of alpha spinal motor neurons?
Innervate extrafusal muscle fibres responsible for contraction
What is the funciton of small gamma spinal motor neurons?
Innervate intrafusal muscle fibres in muscle spindles
What are the 3 types of reflexes?
- Superficial - blink, sneeze
- Deep (myotactic) - patellar
- Visceral (autonomic) - pupillary, bladder
What is Babinski’s relfex?
Flexor response = toes curl down = normal
Extensor response = toes curl up = damage in adults
Extensor response = normal in babies
