Week 6 - Nervous System Flashcards
What is the function of the dendrites?
Receive a stimulus
What makes up the central nervous system?
Brain, spinal cord
What makes up the peripheral nervous system
Ganglia, nerves
Describe glia cells and their function
Support cells
INCREASE SPEED of electrical signals
Describe Schwann cells and their function
Support cells (glia cells) for neurons of PNS
Wrap around the axon
What is the space between Schwann cells called?
Nodes of Ranvier
What are the glia cells of the CNS called
Oligodendrocytes
What is the resting membrane potential?
-70 mV
What is the ratio of sodium to potassium in the sodium/potassium pump?
Pump three sodium ion out of the cell for every two potassium they bring in
3 Na : 2 K
Explain the action potential
- RESTING STATE
Resting potential (-70 mV). - DEPOLARIZATION
Stimulus received, sodium channels open and rush inside the cell. Becomes less negative (-55 mV) - RISING PHASE
Gates open. Massive amount of sodium rushes inside the cell. (+55 mV) - FALLING PHASE
Sodium gates close, potassium gates open. (-90 mV) - UNDERSHOOT
Restored. (-70 mV)
How do Schwann cells makes transmission faster?
Lipid rich segments don’t conduct electricity. It skips along the nodes of Ranvier
What is the skipping along the nodes of Ranvier called?
Saltatory conduction
Explain temporal summation
Multiple impulses from the same stimulus excite the neuron. It forces the potential to -55 since it doesnt have enough time to go back down
Explain spatial summation
Multiple different stimuli activate the same neuron at the same time. Pushes the potential to -55 mV
What are neurotransmitters?
Signalling molecules of neuronal system
What is neuroplasticity?
The ability to change the neurvous system after birth. «faire des connections»
Get more synapses
Define transduction
The conversion of a stimulus’ energy to a change of membrane potential of a receiving cell
How does the width of the receptive field of dendrites affect perception?
Wider the field the less specifically you can pinpoint
Wide on upper back
Very narrow on hands, face
What are naked dendrites
Bare ending.
Pain receptor
What are mechanoreceptor cells?
Cells with gated ion channels that respond to physical deformation
What is a statocyst?
Fluid filled spherical structure lined with cilia and filled with granules called statolith
Cilia can sense where statoliths are which causes canals to open, reaching action potential of -55 and makes the insect want to flip
What structure makes an insect want to flip when it’s on it’s back?
Statocyst
Explain hearing
Soudwaves travel into outer ear, hit the tympanic membrane.
Tympanic membrane vibrates and transfers it to three bones: the malleus, incus and stapes. THIS AMPLIFIES THE SOUND WAVES
Hits the oval window. Sound waves get to cochlea. Reaches the round window. VERY RELIANT ON THAT THE PRESSURE OF OUTER AND MIDDLE EAR ARE THE SAME
Pressure is applied to cochlear duct
Mechanoreceptor cells (hair cells)
What are the three parts of the ear?
Outer, middle, inner
What are the mechanoreceptors of the ear called?
Hair cells
Define pitch
Frequency of sound waves
What are chemoreceptors?
Sensory cells that detect taste, smell and osmoregularity
Explain taste buds
Clusters of chemoreceptors (5 types- each specialized to a taste)
What are the 5 tastes
Sweet
Salty
Bitter (MOST COMLEXE)
Sour
Umami
What is olfaction?
Smell
What is gustation?
Taste
Why do you feel tired after an exam?
CNS takes up a bunch of energy to think fast and hard
What are the three bones that help amplify sound waves?
the malleus, incus and stapes.
What is calcium’s role in muscle contraction?
Calcium allows myosin to pull the filaments
