1
Q
what is the reflex arc
A
stimulus -> receptor -> sensory neurone -> CNS -> relay neurone -> motor neurone -> effector (muscle or gland)
2
Q
name 4 receptors
A
- baroreceptors
- chemoreceptors
- proprioceptors
- thermoreceptors
3
Q
what is cell signalling
A
the process by which, cells communicate with one another, where chemicals from one cell bind to receptors on another cell e.g. neurotransmitters.
4
Q
what are found at the end of sensory neurones
A
pacienion corpuscles
5
Q
what is habituation
A
grow more sensitive, due to to exposure leading to oversensitivity
6
Q
what is a nerve
A
an enclosed cable like bundle of neurones
7
Q
what is the spinal cord
A
a column of nervous tissue, running down the back. Neurones feed into and come out of it:
8
Q
what is grey matter
A
- synapses -unmyelinated relay neurones
- many cell bodies
9
Q
what is white matter
A
- myelinated axons
- relatively few cell bodies
10
Q
nerve impulses, are said to be?
A
all or nothing responses
11
Q
what is the threshold value
A
-55Mv
12
Q
what has to be reached in order to generate an action potential
A
the firing threshold (-55mv)
13
Q
what is the threshold value
A
the minimum receptor potential needed to generate an action potential.
14
Q
what is the generator potential
A
the change in electrical potential of membrane, generated in response to a stimulus (e.g. pressure)
15
Q
what do Pacinian corpuscles respond to
A
a change in pressure
16
Q
what is the function of a thermoreceptor
A
- to respond to a change in body temperature
- found in the skin and hypothalamus
17
Q
what is the function of a baroreceptor
A
- to respond to a change in blood pressure
- found in the carotid artery
18
Q
what is the function of a osmoreceptor
A
- respond to a change in blood water potential
- found in the hypothalamus
19
Q
page 13 know the summary
A
yes or no
20
Q
what do reflexes allow the body to do
A
- to make involuntary adjustments to changes in the external environment to help control the internal environment
21
Q
what is a monosynaptic reflex
A
when a sensory neurone, directly links to a motor neurone ( i.e. 1 synapse
22
Q
what is a dendron
A
the part of the neurone responsible for transmitting electrical impulses towards the cell body. only found in sensory and relay neurones
23
Q
what are axons
A
singular, elongated nerve fibres that transmit impulses away from the cell body.
24
Q
what is a motor neurones
A
neurones that carry an action potential from the CNS to the effector (muscle or gland)
25
what is the myelin sheath
an insulating fatty layer around a neurone that consist of several layers on membrane an thin cytoplasm from a Schwan cell.
26
what is the neuromuscular junction
the structure at which a nerve meets the muscle, similar in action to a synapse
27
what is neurone
a specialised cell which transmits impulses in the form of action potentials
28
what are relay neurones
neurones within the CNS that allow sensory neurones to communicate with motor neurones. they are never myelinated
29
what are sensory neurones
neurones that carry an action potential from the sensory receptor to the CNS
30
what is a transducer
a cell that converts one form of energy into another - in the case of sensory receptors, to an electrical impulse.
31
what are sodium ion channels
protein channels in cell membranes that actively transport sodium ions out of a cell and potassium ions into the cell
32
myelination
myelinated neurones are insulated by an individual myelin (fatty) sheath
33
what keeps the myelin sheath alive
Schwan cells
34
how long is a Schwan cell
about 1mm
35
what is the function of the myelin sheath
to prevent ion movement across the neuron membranes so movement can only occur at the node of ranvier.
36
what is the function of myelinated neurones
carry action potential over long distances quickly.
37
what is the function of non myelinated neurones
involved in coordination actions, where speed is less important e.g. digestion
38
what can be said about the diameter of an axon
- the greater the diameter, the faster the transmission
- if narrower, there is an increased resistance to flow of ions (so slower)
39
what is the conduction speed of myelinated neurones
up to 120 m/s
40
what is the conduction speed of nonmyelinated neurones
up to 0.5 m/s
41
what are the nodes of Ranvier
gaps in the myelin sheath at intervals of 1-3 mm
42
what can be said about a resting axon
that there is a slightly negative electrical potential on the inside compared to the outside.
43
when is the neurone said to be at rest
when it is not transmitting an action potential, but it is in fact actively pumping ion using the sodium/potassium pump.
44
how many sodium ions are pumped out and how many potassium ions are pumped in.
- 3 sodium pumped out
- 2 potassium pumped in
45
what is an action potential
a brief reversal of the potential across the membrane of a neurone causing a peak of +40mV compared to the resting potential of -60mv.
46
describe the resting potential
- membrane, is polarised i.e. a potential difference is -65mv, inside relative to the outside.
- the generation of an action potential is due to the stimulation of receptors or synaptic transmission
47
what is depolarisation
- sodium channels open and sodium diffuses into the axon and it becomes more negative/positive and reaches the threshold potential (-55mv)
- voltage gated sodium sodium channels open and many sodium ions influx. therefore, the inside becomes increasingly positive compared to the outside and the potential difference reaches 40Mv
48
what is repolarisation
- voltage gated sodium channels close and volage gated potassium channels open, therefore potassium ions move out of the neuron via diffusion and the potential difference is restored
- more negative inside than outside.
49
what is hyperpolarisation
the potential difference overshoots (to -70mv) making the cell hyperpolarised, i.e. more potassium ions, have excited the cell than is necessary.
50
what is the redistribution of ions
the sodium and potassium pump, restores the normal distribution of ions, to return the cells to its normal resting potential (-65/-70 mv)
51
what can be said about the all or nothing law
- if the stimulus is below a certain threshold, there is no response, because no action potential is generated.
- if the stimulus intensity, exceeds the threshold, an action potential is therefore generated.
52
what can be said about the strength of a given stimulus
the strength of a stimulus, is determined by the brain and by the frequency of impulses along the neurone, as well as the number of neurones carrying the action potential
53
how do we determine the nature of the stimulus
it is determined by the position of the receptors and the sensory neurone bringing the information
54
know the action potential summary on page 30
- 1 - shit
- 2 - alright
- 3 - average
- 4 - good
- 5 - perfect
55
after an axon has transmitted an impulse, it cannot transmit another straight away because:
- membrane, has to be repolarised from + 40mv -> -65 Mv.
- resting distribution of NA+ + k+ ions is restored.
56
what is the absolute refractory period
no additional stimulus, no matter how strong is able to produce an action potential. NA+ concentration is high in an axon + NA+ channels must return to resting.
57
what is the relative refractory period
only more intense stimulus, can produce an action potential, this is during repolarisation and hyperpolarisation period.
58
what is the importance of the refractory period
1. The action potential is propagated forwards, towards a region which is not in refractory period -> impulses, travels in one direction only.
2. it separates action potential as by the time the second action potential is generated, the first has passed further down line.
59
transmission of the action potential in a nonmyelinated neurone
1. voltage gated sodium channels open and sodium ions diffuse in
2. a localised increase in sodium inside (AP = 40MV)
3. the sodium ions, diffuse along the axon dendrite, a short distance from a high to low concentration
4. causes a slight depolarisation, therefore voltage gated sodium channels, further along the neurone open (NA+ in +40MV)
60
know the saltatory conduction on page 37
- 1 - shit
- 2 - alright
- 3 - average
- 4 - good
- 5 - perfect
61
what is excitatory post synaptic potential
where the membrane potential, of the post synaptic neurone moves closer to the threshold value, due to a small depolarisation as a neurotransmitter causes opening of channels, which allow positive (Na+) charges to enter the post synaptic neurone.
62
what is inhibitory post synaptic potential
where the membrane potential of the post synaptic neurone moves away from the threshold due to a small hyperpolarisation as a neurotransmitter causes opening of channels, which allow negative charges (Cl-) to enter the post synaptic neurone and or positive charges (k+) to leave the post synaptic neurone.
63
what is the role of synapses
- allow neurones to communicate
- ensure one way transmission between neurones
- divergence
64
give an example of divergence
In a reflex, one post synaptic neurone, may carry out the response and another post synaptic neurone, informs the brain on what happened.
65
what is spatial summation
simultaneous EPSPs from multiple neurones bring the trigger zone to threshold
66
what is temporal summation
Successive EPSPs bring the trigger zone to threshold
biology a level OCR
flashcards
Decks in class (32)
# Cards
-
cell structure41
-
Nucleotides and Nucleic acids66
-
biological molecules (carbohydrates, lipids and proteins)67
-
enzymes55
-
biolgical membranes41
-
Exchange surfaces79
-
transport in animals94
-
communicable diseases85
-
biodiversity46
-
classification and evolution78
-
Recycling materials in the ecosystem38
-
transport in plants55
-
communicable diseases SLOP40
-
stages of mitosis and meiosis12
-
exchange surface and transport SLOP2
-
module 3 exchange and transport (booklet 2)12
-
communication and homeostasis41
-
photosythesis71
-
neuronal communication66
-
plant reponses32
-
hormonal communication43
-
respiration62
-
excretion - the liver20
-
cellular control37
-
kidney34
-
patterns of inheritance65
-
Animal responses (the nervous system and the brain)20
-
muscle notes22
-
manipulating genomes72
-
biotechnology33
-
cloning17
-
characteristic of each kingdom of classification6
