Neurons

Question 1

dominant theory

Answer 1

states that nervous system composed of a continuous structures
*stated that it was composed of continuous network of nerves

Question 2

structure of neurons

Answer 2

100 billion neurons in human brain

Question 3

dendrites

Answer 3

extends away from cell body (main input)

Question 4

soma

Answer 4

cell body: contains nucleus & genetic information

Question 5

axon

Answer 5

extends off of soma, connects to other neurons (main output)

Question 6

nucleus

Answer 6

contains genetic info, directs protein synthesis and supplies energy & resources

Question 7

synapse

Answer 7

place where axon & dendrite connect

Question 8

myelin sheath

Answer 8

surrounds axon for insulation

- allows signal of one neuron to the next rapidly

Question 9

terminal button

Answer 9

end of axon, forms synapses with spines (protrusions) of dendrites

Question 10

synaptic gap/cleft

Answer 10

space between presynaptic terminal button, and postsynaptic dendritic spine

Question 11

synaptic vesicles

Answer 11

in terminal button; packages of neurotransmitters

Question 12

neurotransmitters

Answer 12

chemical substance released by terminal button and act on post synaptic cell

Question 13

sensory neuron

Answer 13

receive info about world around us

Question 14

motor neurons

Answer 14

initiate movement and behaviour

Question 15

interneurons

Answer 15

process the sensory input from our environments into meaningful representations, plan appropriate behavioural response and connect to motor neurone to execute those behavioural plans

Question 16

3 main categories of neurons

Answer 16

1. unipolar neurons
2. bipolar neurons
3. multipolar neurons

Question 17

unipolar neurons

Answer 17

structured in a way that is ideal for relaying info forward

• 1 axon & no dendrites
• communicating body temperatures through spinal cord to brain

Question 18

bipolar neurons

Answer 18

sensory perception

• structured to have one axon + one dendrite
• to acquire and pass sensory info to brain

Question 19

multiple neurons

Answer 19

one axon, many dendrites

• most common
• communicating sensory & motor info in brain

Question 20

glia cells

Answer 20

oligodendroglia (forms myelin sheath), microglia(biggest debris of dead neurons)

Question 21

2 stages of electrochemical action

Answer 21

1. chemical conduction & dendritic input to the initiation of an action potential within a neuron
2. chemical transmission across the synaptic gap between the presynaptic neuron & the post synaptic neuron

Question 22

resting membrane potential

Answer 22

fluid of neurons composed of combination of ions
(Na+, K+, Cl-, anions)
Separated by cell membrane (lipid bilayer)
Ion Channel in Membrane - ions pass through and go from high to low concentration

Question 23

Components of Resting Membrane Potential

Answer 23

voltage inside cell relative to outside
* (-70mV) while at rest.
Anions - High conc. outside cell, contribute to negative charge of RMP

Potassium - stays inside cell bc attract to anions

Chloride - stays outside of cell

Sodium - cannot pass through membrane, stays outside cell…. if inside, pushed out by sodium-potassium pump

Question 24

action potential

Answer 24

an all-or-nothing response that occurs w a change in charge from it’s resting membrane potential (-7omV) in a more positive direction

• depolarization
  ex: either 1 or 0, nothing in between

Question 25

threshold of excitation

Answer 25

specific membrane potential that neurons must reach to initiate action potential (around 50mV)
change in voltage = 100mV

Question 26

inputs cause fluctuations in Neuron’s membrane potentials

Answer 26

1. excitatory postsynaptic potentials (EPSPs)
   - causes membrane to be more positive closer to threshold of excitation
2. inhibitory postsynaptic potentials (IPSPs)
   membrane potential becomes more negative & further from the threshold of excitation

Question 27

ionotropic receptors

Answer 27

Ion channels allowing ions to pass through cell membrane under specific conditions

Question 28

depolarized

Answer 28

Na+ channels open, Na+ enters cell

• channels become refractory (can’t open again until RMP)
• K+ channels open
• K+ exit, returning back to RMP

Question 29

Nodes Ranvier

Answer 29

Gaps in myelin… no fluid exists

- Salvatore conduction AP jumps from node to node