Week 1 (lectures 1-3)- Overview of CNS/Transmission of Information

Question 1

what are the 3 main functions of the CNS?

Answer 1

sensory input

integration (e.g SC or brain)

response to internal/external stimuli

Question 2

what is meant by sensory input?

Answer 2

monitors changes/events internally/externally (i.e. stimuli)

Question 3

what are the cells responsible for receiving sensory information called?

Answer 3

receptors

Question 4

what is meant by integration?

Answer 4

parallel processing/interpretation of sensory information to determine appropriate response

Question 5

what is meant by response to stimuli?

Answer 5

activation of muscle/organ/gland

Question 6

what are the neurones that carry input signals?

Answer 6

afferent neurones

Question 7

what are the neurones that carry output signals?

Answer 7

efferent neurones

Question 8

what 2 things does the CNS include?

Answer 8

brain

spinal cord (SC)

Question 9

what are the main functions of the SC?

Answer 9

carry messages to/from the brain

relay messages that require a faster response so they bypass the brain (reflex arc)

Question 10

what is the essential difference between the CNS and PNS?

Answer 10

PNS= all neurones outside of brain/SC (i.e CNS)

Question 11

name 3 key functions of the PNS?

Answer 11

connect CNS to rest of the body (muscles, organs etc)

carry sensory/motor information to/from CNS

regulate involuntary functions (e.g. heart)

Question 12

what 2 branches is the PNS split directly into?

Answer 12

somatic nervous system (SNS)

autonomic nervous system (ANS)

Question 13

what is the SNS in control of?

Answer 13

voluntary movement via skeletal muscle

Question 14

what part of the brain is the SNS connected to?

Answer 14

motor cortex

Question 15

what are only movements controlled by the SNS that are not voluntary called?

Answer 15

reflexes (reflex arc)

Question 16

what is the ANS in control of?

Answer 16

involuntary functions (e.g. HR, breathing)

Question 17

what are the 2 divisions of the ANS?

Answer 17

Sympathetic nervous system (SyNS)

parasympathetic nervous system (PNS)

Question 18

what is the role of the SyNS?

Answer 18

activate/stimulate body functions q

Question 19

where does the SyNS originate from?

Answer 19

T1-L2/3

Question 20

when is the SyNS activated?

Answer 20

under conditions of stress (i.e. fight or flight)

Question 21

what happens when the SyNS is activated?

Answer 21

postganglionic neurones release noradrenaline

prolonged activation of this= elicit release of adrenaline from adrenal medulla

this does things like increase HR, breathing etc

Question 22

what is the role of the PNS?

Answer 22

essentially relaxes the body after the SyNS has been raising everything (e.g. decreases HR)

Question 23

what are 3 parts of a neurone?

Answer 23

dendrites

cell body (soma)

axon

Question 24

what are dendrites?

Answer 24

‘extensions’ of the soma

Question 25

how long are dendrites?

Answer 25

2μm

Question 26

what is the main function of dendrites?

Answer 26

receive info from other neurones and carry it over soma

Question 27

what things do the soma contain?

Answer 27

nucleus | specialised organelles

Question 28

what is the function of the soma?

Answer 28

provide structure and energy to neurone

Question 29

what is the axon?

Answer 29

long projection starting from the soma

Question 30

what is the main function of the axon?

Answer 30

transmit information (via action potential) to another neurone or cell

Question 31

how many axons does a neurone typically have?

Answer 31

1

Question 32

what are the 4 types of neurones (structural classification)?

Answer 32

anatomic bipolar unipolar multipolar

Question 33

describe an anatomic neurone?

Answer 33

small can't distinguish its dendrites from axons found in brain/sensory organs

Question 34

describe a bipolar neurone?

Answer 34

``` small distinction between dendrites and axons dendrites have extensive branching rare! found in sensory organs ```

Question 35

describe a unipolar neurone?

Answer 35

vary wildly in size dendrite and axon continuous on one side of body found as most sensory neurones in PNS

Question 36

describe a multipolar neurone?

Answer 36

size varies wildly most common neurone in CNS dendric spines increase surface area are the motor neurones controlling skeletal muscle

Question 37

what are the 3 functional classifications of neurones/

Answer 37

afferent (sensory) efferent (motor) interneurones

Question 38

describe afferent neurones and their role?

Answer 38

unipolar cell bodies located in ganglia approx 10milion in a person carry impulses from receptors to CNS somatic AND visceral/autonomic

Question 39

describe efferent neurones and their role?

Answer 39

Bipolar approx 0.5million in a person cell body located in CNS carry impulses from CNS to peripheral effectors

Question 40

describe interneurones and their role?

Answer 40

multipolar most are located in brain and SC approx 20billion in a person number involved in a process depends on complexity of response needed

Question 41

name 4 types of supporting cells?

Answer 41

neuroglia astrocytes microglia ependymal cells

Question 42

what do neuroglia do (supporting cells)?

Answer 42

provide metabolic and physical support for neurones | protect/maintain optimum functioning of nervous system

Question 43

what do astrocytes do (supporting cells)?

Answer 43

provide structure, support and nutrition holds 'family' together integral to blood-brain-barrier exclusive to CNS and are star shaped

Question 44

what do microglia do (supporting cells)?

Answer 44

monitor the health of neurones | can transform into macrophages and become mobile (fight invasive organisms/phagocytosis of dead neurones)

Question 45

what do ependymal cells do (supporting cells)?

Answer 45

keep things moving line brain/SC tissue cilia maintain circulation/flow of cerebrospinal fluid

Question 46

define the 'resting membrane potential'?

Answer 46

difference in change between interior/exterior of cell at rest

Question 47

what is the resting potential of a neurone?

Answer 47

-70mV

Question 48

name 2 things he resting potential depends on?

Answer 48

permeability of membrane to ions electrochemical gradients

Question 49

what are the 3 key ions?

Answer 49

Na+, K+, Cl-

Question 50

what is the threshold for an action potential?

Answer 50

-55mV

Question 51

what is temporal summation?

Answer 51

single presynaptic neurone firing many times in quick succession increased frequency = EPSP comes together AP generated once threshold is reached

Question 52

what is spatial summation?

Answer 52

multiple/simultaneous EPSP's at different locations on neurone sufficient spatial summation of EPSP's= AP triggered

Question 53

what does EPSP stand for?

Answer 53

excitatory postsynaptic potential

Question 54

what is saltatory conduction and why is it the best way for information to travel?

Answer 54

AP 'jumps' between nodes of Ranvier= higher speed

Question 55

do small neurones have high or low resistance to AP?

Answer 55

high (unmyelinated axons)

Question 56

do large neurones have high or low resistance to AP?

Answer 56

low (myelinated axons)

Question 57

what is myelin made up of?

Answer 57

protein/fatty substances

Question 58

what effect does myelin have on AP?

Answer 58

facilitates it to move quickly up an axon

Question 59

what is responsible for myelination in the PNS?

Answer 59

schwann cells

Question 60

what is responsible for myelination in the CNS?

Answer 60

oligodendrocytes

Question 61

what is a synapse between?

Answer 61

2 neurones

Question 62

what is the connection between a neurone and a muscle called?

Answer 62

neuromuscular junction

Question 63

what is the presynaptic side of a synapse?

Answer 63

axon

Question 64

what is the postsynaptic side of a synapse?

Answer 64

dendrite/soma

Question 65

what are the 4 stages of synaptic transmission?

Answer 65

1) AP arrives at axon terminal, and vesicles fuse with membrane 2) Ca++ channels release neurotransmitter into synaptic cleft 3) neurotransmitter diffuses across synaptic cleft to fuse with receptors on postsynaptic neurone 4) receptors activated, and ion channels open; creates localised change in electric potential, and travels a short distance