quiz 1 Flashcards

Question

what are dendrites

Answer 1

-Extension of neuron that receives information from receptors (in case of sensory neurons) or other nerve cells (motor neurons) - Conduct impulse toward cell body -highly branched so increases SA to receive info

Answer 2

-Also called soma -Contains nucleus -site of metabolic reactions -Processes info from dendrites -if stimulus is large enough, info is passes on to axon -

Answer 3

-Extends from the cell body and carries an impulse towards other neurons or effectors -longest part in neuron -terminal end of an axon branches into many fibres so to communicate with adjacent neurons, glands or muscles the axon terminal releases chem signals into space between it and the receptors/dendrites of neighboring cells

Answer 4

-Also called axon bulb -End of axon -Where chemicals (called neurotransmitters) are released into the space between it an the receptors or dendrites of neighbouring cells

Answer 5

-A white, fatty, insulating layer on an axon -Axons with this are called myelinated -Protects neuron -Speeds rate of nerve impulse transmission by acting as an electrical insulator -can heal itself

Answer 6

-A type of glial cell -Form myelin sheath by wrapping themselves around the axon -Schwann cells in PNS -Oligodendrocytes in CNS

Answer 7

-areas between myelin sheaths

Answer 8

-In CNS neurons that are myelinated are called white matter -Most neurons in PNS are myelinated -Myelin can repair itself so damage isn’t necessarily permanent

Answer 9

-In CNS neurons that are NOT myelinated are called grey matter -No myelin so cannot repair itself so damage is permanent

Answer 10

- Simplest neural pathway (fewer neurons involved, shorter distance for info to travel) -Impulse travels through spinal cord and out to effector * Does NOT need the brain * Another impulse (requiring greater time) is sent to the brain for processing * Involuntary/ no conscious control * Response is innate (automatic)

Answer 11

- neurons can establish a voltage difference between the inside and outside of the cell membrane. they use this voltage difference to generate a neural impulse.

Answer 12

- There is always a charge separation across a membrane of an axon  Resting membrane: -70mV -also called polarization, when have positive and negitive side -is the difference in electric potential between the interior and the exterior of a biological cell.

Answer 13

-Uses energy  Moves sodium out  Moves potassium in  Moves more sodium out than potassium in so get more positive charge on outside of axon

Answer 14

Diffusion of ions  No energy needed  Sodium moves into cell  Potassium moves out of cell faster  Build up of positive ions outside axon

Answer 15

Minimum amount of stimulus required to produce a response Each neuron has a set amount of stimulation needed to cause an action potential. Stimulation will cause the axon to become more permeable to sodium Usually the threshold is close to -55mV

Answer 16

Upon excitation (caused by a stimulus), the nerve cell becomes more permeable to Na+ than K+  Na+ channels open and Na+ ions rush into the cell via diffusion. Potassium channels close. * Charge of axon now +35mV * Takes only a millisecond!

Answer 17

The axon’s charge going from -70mV to +35 mV is called depolarization * Sodium (Na+) is entering cell * Once enough Na+ has entered the cell to completely change the charge inside the cell from being negative to being positive, an action potential has occurred.

Answer 18

frequency (how many) of impulses.

Answer 19

The process of restoring the original polarity. * Due to change in membrane potential: 1)Potassium moves out through channels 2)Sodium channels close

Answer 20

Membrane potential overshoots to nearly -90mV because too much K+ is released.

Answer 21

The time it takes a cell to repolarize  Lasts a few milliseconds after an action potential  The nerve cell must repolarize before it can conduct another action potential.