lecture 3

Question 1

why do more complex organisms need a NS

Answer 1

Cells on the inside of the body are not in direct contact with the outside world

• also live in different environments
• have become specialised

Question 2

in order for the organisms to function cell activities must be

Answer 2

coordinated

Question 3

what systems are used to coordinate cella activity

Answer 3

endocrine and NS

Question 4

ES

Answer 4

specialised to secrete chemicals - hormones into the blood stream - relatively slow and general

Question 5

NS

Answer 5

specialised to transit electrical impulses between two or more cells
fast and precise

Question 6

neural impulses provide

Answer 6

constant/ rapid communication

Question 7

Neurons are specialised to

Answer 7

generate and transmit electrical impulses which are rapid , over great distances and precise

Question 8

neurons virtually have no

Answer 8

possibility to store energy

so glucose and oxygen must constantly be supplied

Question 9

life span of neutron s

Answer 9

neurons do not divide

they develop from neural stem cells - neurogenesis

Question 10

glia cells

Answer 10

provide protected environment for euros to survive

Question 11

types of glia cells

Answer 11

astrocytes
microglia
oligodendroglia

Question 12

astrocytes

Answer 12

star shaped
physical and nutritional support for neurons
transport nutrients from blood vessels to neurones
plays role in neural signals transmitting

Question 13

microglia

Answer 13

very small
mobile for defensive function
produce chemicals that aid repair of damaged neurons
digest dead neurons - phagocytosis

Question 14

oligodendroglia

Answer 14

large flat branches
wrapped around axons
consist of fatty substance - myelin
insulating the axon

Question 15

electrical activity - resin potential

Answer 15

when a neuron is not sending a signal - its at rest

inside of the Huron is negative to the outside

Question 16

protein channels in cell membranes allows

Answer 16

specific ions to enter/ leave the cell

Question 17

sodium potassium pump

Answer 17

maintains resting potential
3 sodiums fo OUT
2 potassium IN

Question 18

If channels were passive

Answer 18

ions would freely flow - membrane would depolarise so there is no concentration differences = no electrical activity

Question 19

sodium ions go

Answer 19

against the concentration gradient

Question 20

depolarisation

Answer 20

positive ions In (negative ions out)

inside is less negative than usual

Question 21

hyperpolarisation

Answer 21

negative ions IN(positive ions out)

inside MORE negative than usual

Question 22

signal transmission - electrical

Answer 22

in the dendrites and soma

passive process

Question 23

transmission in the axon is

Answer 23

active
ions move locally through the cell membrane
generated at axon hillock

Question 24

sodium channels open or close in response

Answer 24

to electrical changes at the membrane

Question 25

inflow of sodium ions

Answer 25

membrane depolarises - less negative
sodium channels open
sodium ions enter
membrane depolarises further- more positive on the inside

Question 26

if membrane potential at axon hillock remains below threshold

Answer 26

resting potential returns

Question 27

if membrane depolarises further

Answer 27

more sodium channels open - more depolarisation

Question 28

when threshold is reached

Answer 28

all sodium channels open

generated action potential

Question 29

when threshold is reached , potassium channels

Answer 29

open - potassium ions rush OUT of cell - membrane reprises

Question 30

why does the action potential not travel backward

Answer 30

because during hyperpolarisation (more negative ) membrane is more difficult to depolarise

Question 31

each burst of depolarisation acts as a

Answer 31

trigger - influx of positive ions

opens sodium channels

Question 32

properties of AP

Answer 32

no decay
all or nothing principle
discontinuous - minimal time between subsequent AP
fast

Question 33

saltatory conduction

Answer 33

sensory and motor neurons are myelinated
insulation - prevent ion inflow and outflow
rapid

Question 34

nodes of ranvier

Answer 34

gaps that interrupt insulation every 1-2mm