Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A-level Biology > 6- Nervous Sytem And Homeostasis > Flashcards

6- Nervous Sytem And Homeostasis Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

Why do we need a nervous repsone

A

Selection pressure favours orgaisms with the more appropriate response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a stimulus

A

A detectable chmage In the internal or external environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the response

A

What an organism can do to react to the stimuli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are cells sensitive to stimulus called

A

Receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

T or f
Receptors are specific to stimuli they recieve

A

T

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

response produced by an effector can be at what 2 levels

A

At a molecular level ( hormones)
Behaviour of Whole organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is taxis

A

The moment of an animal towards or away form a stimulus in one direction
Eg, chemotaxis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is kinesis

A

Orienting behaviour where an animal reduced or increases it rate of movement as the intensity of a stimuli increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is an example of kinesis

A

Woodlois start to move when they start to dry out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is Tropism

A

The growth movement of part of a plant in response to a directional stimuli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the reflex escape response

A

Rapid automatic response to escape predators

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why do plants respond to external stimuli

A

Avoid stress
Avoid being eaten
Enhance survival
Improve chances of successful breeding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is phototropism response to

A

Light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is geotropism response to

A

Gravity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is chemotropism response to

A

Chemicals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is thigmotropism response to

A

Touch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What controls the response of plants

A

hormones control / coordinate plant response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the chemicals in plants still considered hormones eventhough they are not produced by the endocrine system

A

They are transported away from site of manufacture to a target cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Do hormones allways move from site of manufacture to target cell

A

No some hormones stay in the cell that makes them and exerts their effects within the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Descirbe hormones in plants

A

Produced by a specific cell
Have a specific shape
Bind to reseptors on the target cell
Receptor complementary to the shape of the hormone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How are hormones carried around the plant

A

Diffusion
Active transport
Mass flow ( phloem / xylem)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is it called when hormones amplify each other

A

Synergy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is it called when hormones cancel each other out

A

Antagonistic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Where does growth in a plant occur

A

Meristem

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are the 3 areas of the meristem ( and be able to label)

A

Apical meristems
Lateral bud meristems
Intercallary meristem

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What causes phototropism

A

All shoots bend towards the light
As the shaded side elongates faster as light causes auxins to be transported to shaded side which promotes growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What causes gravptropism

A

Auxin increases in side next to the stimulus and inhibits growth. So upper roots grow quicker and bend roots ( down ) towards stimuli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What does IAA stand for

A

Indolaceticacid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the commercial use of auxins

A

Promotes cell gworth so used in cuttings
Seedless fruits
Herbicides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is the commercial use of gibberellins

A

Seed germination and grows the stems
Delays senescence ( aging )
Imporves shapes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is the commercial use of cytokinins

A

Promotes cell division
Prevents yellowing
Mass production

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is the commercial use of ethene

A

Promotes fruit ripening
Promotes fruit drop
Female sex expression in cucumbers
Promotes lateral growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is the acid growth hyposthesis

A

The action of IAAs increases the plasticity of cell walls in young cells (mature cells are more rigid)
Active transport of H+ ions form cytoplasm to spaces in the cell wall causing cell to become more plastic and elongated by expansion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Describe the plant repsonse experiment carried out by Charles Darwin;

A

He observed young grass shoots growing towards the light
He proposed stimuli of the light was detected by the tip of the shoot
He cut of the tip in one
One with a tip bent towards the light , one with no tip had no response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Desicbe the Peter boysen-jenson experiment

A

He tried to prove weather chemical substances produced in the top and transported down the stem and cause a repsonse or an electrical signal
He put a thin impermeable barrier of mica on light side# movement of chemical down shaded side caused stem to bend toward slight

The put the mica on the shaded side - the chemical was blocked by the mica so no response

Then he put a block of gelatin across whole stem- an electrical signal would be blocked by a chemical can still move , the stem bent towards the light so chemicalnot electrical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Desicbe paal plant response experiments

A

He investigated how chemical messagers worked - he removed tops of shoots and put them in darkness
The tips bent towards side where no tips where present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Describe the Winslow brings plant response experiment

A

How Light caused uneven distribution of IAA
1- two tips , one had light and bent - the total IAA is each was approx the same

2- then 1 tip with a thin glass plate separating the side of the shoot
Amount of iaa collected is apr. The same

3- half glass plate
Bent - 30% collected in light side amd 70% on shaded elongated side

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Why do animals respond to changes in their internal environment.

A

To make cure that the conditions are always optimal for their metabolism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is any change in the interbank or external environment called

A

A stimulus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What detects stimuli

A

Receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What can receptors be

A

Cells or proteins on cell surface membranes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What are effectors

A

Cells that bring about a response to a stimulus, to produce an effect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What do effectors include

A

Muscle cells and cells found in glands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

How do receptors communicated with effectors

A

Via the nervous system or the hormonal system or sometimes using both

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What is the nervous sustem made. Up of

A

Neurones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What are the 3 main neuron types

A

Sensory neurones
Motor neurones
Relay neurones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What do sensory neuron’s do

A

Transmit electrical impulses form receptors to the central nervous system - the brain and spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What is included in the CNS

A

Brain and spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What do motor neurons do

A

Transmit electrical impulses form the cns to effectors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

What do relay neurons do

A

Transmit electrical Impulses between sensory neurons and motor neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What are electrical impulses also called

A

Nerve impulses
Or
Action potentials

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Desicbe what happens when a stimulus is detected to an effect or

A

1- stimulus detected by receptor cells and an electrical impulse is sent along a sensory neurone
2- when an electrical impulse reached the end of a neurone, chemicals called neurotransmitters take information across to the next neuron which then sends an electrical impulse
3- the cns ( the coordinator) processes the information and sends impulses along motor neurons to an effect or

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

What chemicals take information from one neurone to the next

A

Neurotransmitters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

What is the peripheral nervous system made up of

A

Neurons that connect the cns to the rest of the body. It also has 2 differnt systems

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

What 2 ways is the nervous system split

A

Central nervous system
Peripheral nervous sustem

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

What 2 systems are a part of the peripheral nervous system

A

Somatic
Autonomaic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

What does the somatic nervous system control

A

Conscious activates
Eg, running

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

What does the autonomic nervous system control

A

Unconscious activities
Eg. Digestion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

What 2 systems does the autonomic nervous system and what effect do they have on each other

A

Opposite effect on each other
The sympathetic nervous system
The parasympathetic nervous system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

What does the sympathetic nervous system condo

A

Gets the body read for action
It’s the flight or fight system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

What does the parasympathetic nervous system do

A

Calms the body down
It’s the rest and digest

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

What are reflexes

A

Rapid
Automatic responses to stimuli
A reflex is where the body response to a stimuluswithout making a conscious decision to repsond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

Why does information travel real fast from receptor to effector when it’s a reflex

A

Don’t spend time deciding how to repsond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

Why do simple reflexes help organisms to protect the body

A

They’re rapid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

What is the pathway of neurones linking receptors to effectors in a reflex is called what

A

Reflex arc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

Describe the reflex arc with the example of a had withdrawal response to heat

A

Thermoreceptors In the skim detector the heat stimulus
The sensory neurons carries impulses to the relay neurone
The relay neuron connects to the motor neurone
The motor neurone sends impulses to the effector
Your muscle contracts to withdraw your ban and stop it being damaged

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

If there is a ….. neurone Involved in the simple reflex arc then it’s possible to override the reflex
. How does this link to hand withdrawn in response to heat

A

Relay
In the example above your brain could tell your hand to withstand the heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

Nervous system communication is
…..
…..
……

A

Localised
Short lived
Rapid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

Why is nervous system communication localised

A

When an electrical impulse reaches the end of a neuron, neurotransmitters are secreted directly onto target cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

How is nervous system communication short lived

A

Neurotransmitters are quickly removed once they’ve done their job

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

3 ways , plants increase their chance of survivals by responding to changes in environment

A

1- grow towards lifht to maximise light absorbtion for photosynthesis
2- sense gravity Si roots and shoot grow in right direction
3climbing plants sense touchy so can find things to climb up and reach the sunlight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

What is a positive tropism

A

The growth is towards the stimulus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

What is negative tropism

A

The growth is away for the stimulus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

Are shoots positively phototrophic or negative

A

Positively - they grow towards the light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

Are roots postivitley phototophic or negatively

A

Negatively- thus grow away from light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

Are shoot positively or negatively gravitrioic

A

Negative - they grow upwards

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

Are roots positively gravitrioic or negative

A

Positive they grow downwards

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

What do3s auxin do

A

Stimulate growth of shoot by cell elongation , the cell walls become loose and stretchy so the cell become longer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

What does high conc of auxin in the roots do

A

Inhibit growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

What are IAAs

A

An important auxin that’s produced in the tips and shoots in flowering plants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

What does IAA do

A

Moved around the plant to control tropisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

How does IAA move around the plant
And what does this result in

A

Moves by diffusion and active transport over shot distances and via the phloem for long distances
Results in differnt parts of the plant having differnt concentrations of IAA. An uneven distribution of IAA means there’s uneven growth of the plant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

Describe p how you can use choice chambers to investigate animal response

A

1( light intensity
- cover one half with black paper , place 10 wood louche in the centre and cover , after 10 mins count number of woodlouse on each side repeate (they should end up on dark side - as it keeps them concealed under stones during the day so away form predators)

2) humidity
- damp filter paper on one side and a drying agent on the other. Lid on, wait 10 mins
(The damp conditions are more favourable as it reduces water loss)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

How do woodlice show a kinetic response to humidity

A

In high humidity they move slowly and turn less oftern
So that they stay where they are
As the air gets drier they move faster and turn more oftern so they move into a new area - this response increwsss rhe chance the woodlouse will move unit an area with higher humidity - reduces water loss in high humidity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

Describe nervous communication

A

Electrical impulses
Target cells stimulated by neurotransmitters
Rapid ( transmission + response)
Short lived response
Localised
Specifically trageted
Temporary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

Describe hormones

A

Chemicals from endocrine glands, blood plasma to target cells
Target cells have receptors on CSM, change in conc. stimulate them
Slower, less specific, long lasting and widespread.
Hormones travel throughout body but only granger cells response
(Effect permanent and can be irreversible)
Transmission amd response is slow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

What 2 ways can you Desicbe the nervous system

A

Central nervous sustem
Peripheral nervous system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

What’s included in the CNS

A

Brain and spinal chord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
89
Q

What 2 ways is the peripheral nervous system divided

A

Sensory receptors —> CNS
Motor CNS —-> effector

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
90
Q

What 2 ways is the motor nervous system divided

A

Voluntary NS
Automatic NS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
91
Q

What sit he voluntary NS

A

Carries nerve impulses to body muscles, voluntary control

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
92
Q

What is automatic NS

A

Nerve impulses carried to glands, smooth muscles and cardiac muscle and is not under voluntary control - its involuntary (unconscious)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
93
Q

Describe the reflex arc

A

Stimulus
Receptor
Sensory neuron
Coordinator
Motor neuron
Effector
Repsonse

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
94
Q

What are the 3 neurons and where do they go

A

Sensory neurons ( receptors to CNS)
Interneurons ( to motor neuron )
Motor neuron ( to effectors)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
95
Q

Key features of a reflex arc

A

Automatic
Innate
Cannot be learned
Don’t involve the brain
Immediate
Fast ( short neuron pathway as only 1 or 2 synapses)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
96
Q

Learn the structure of the myelinated never cell

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
97
Q

How can you tell the difference between the motor /intermediate and sensory

A

Motor and intermediate - the cell body is at the end of
Sensory the cell boys is in the middle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
98
Q

T or f
Receptors only detect one particular stimulus

A

T

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
99
Q

What are some receptor types

A

Cells (eg, photoreceptors)
Proteins on cell surface memebrane (eg, glucose receptor)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
100
Q

When a nervous system receptor is in its resting state, what is there

A

A differnce in charge between the inside and outside of the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
101
Q

How is the difference in charge between inside and outside of cells generated , in the resting state of the nervous system

A

Generated by ion pumps and ion channels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
102
Q

What is there across the membrane of a nervous system receptor

A

Voltage known as potential difference

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
103
Q

What is the potential differnce when a cell is as rest called

A

Resting potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
104
Q

What happens to potential differnce In receptors when a stimulus is detected

A

The cell memebrane is excited and becomes more permeable , allowing more ions to move in and out of cell. Altering the potential differnce

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
105
Q

What is the change in potential differnce due to a stimulus called

A

Generator potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
106
Q

How does a bigger stimulus effect generator potential

A

Excited the membrane causing a bigger movement of ions and a bigger change in potential differnce
So a bigger generator potential is produced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
107
Q

If the generator potential is big enough what is triggered

A

Action potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
108
Q

What is action potential

A

An electrical impulse along a neuron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
109
Q

When is an action potential only triggered

A

If the generator potential reaches a certain level called threshold level

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
110
Q

T or f
Action potentials are all one size

A

T

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
111
Q

The strength of the stimulus is measured by what

A

The frequency of action potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
112
Q

How is frequency of action potential measured

A

The number of action potential triggered during a certain time period

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
113
Q

Will there be a action potential if the stimulus is too weak

A

The generator potential won’t reach the threshold
So no action potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
114
Q

What are pacinian corpuscles

A

Mechanoreceptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
115
Q

What do mechanoreceptors detect

A

Mechanical stimuli
(Eg. Pressure and vibration )

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
116
Q

Where are mechanoreceptors found

A

In the skin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
117
Q

What do pacinian corpuscles contain

A

End of a sensory neuron ( called sensory Nerve ending )
The sensory nerve ending is wrapped in loads of layers of connective tissue called lamellae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
118
Q

What happens when a pacinian corpuscle is stimulated
Eg. Tap on the arm

A

The lamellae are deformed and press on the sensory Neve ending
This causes the sensory neurons cell memebrane to stretch, deforming the stretch-mediated sodium ion channels
The channels open and sodium ions diffuse into the cell , creating a generator potential
If the generator potential reaches the threshold it triggers an action potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
119
Q

How does light enter the eye

A

Pupil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
120
Q

The amount of light that enters is controlled by what

A

The muscles of the iris

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
121
Q

How are light rays focused in the eye

A

Focused by the lens onto the retina, which lines the inside of the eye

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
122
Q

What does the retina contain

A

Photoreceptors cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
123
Q

What is the fovea

A

An area of the retina where there are lots of photoreceptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
124
Q

How does nerve impulses form the photoreceptor cells work ( eye)

A

Carried form the retina to the brain by the optic Nerve ( which is a bundle of neurons )

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
125
Q

Where the optic nerve leaves the eye it’s called what

A

The blind spot

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
126
Q

Why is where the optic nerve leaves rhe eye called a blind spot

A

There arnt any photoreceptor cells , so it’s not sensitive to light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
127
Q

How does photoreceptors convert light into an electrical impulse

A

1) light enters the eye, hits the photoreceptors and it’s absorbed by light sensitive optical pigments
2) light bleaches the pigments, causing a chemical change and altering the membrane permeability to sodium ions,
3) a generator potential is created and if it reaches the threshold, a neve impulse is sent along a bipolar neurons
4) bipolar neuorne connect photoreceptors to the optic Nerve which takes impulses to the brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
128
Q

What are the 2 types of photoreceptors in the human eye

A

Rods and cones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
129
Q

Where are rods mainly found

A

Peripheral part of the retina

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
130
Q

Where are cones found

A

Packed together in the fovea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
131
Q

What differs between rods and cones

A

They contain differnet optical pigments making ghem sensitive to differnt wavelengths.
Rods only give information in black and white(monochromatic vision) but cones give information in colour (trichromatic vision)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
132
Q

What are the 3 types of cones

A

Each contain different optical pigment
Red sensitive
Green sensitive
Blue sensitivity
( they’re stimulated in differnt proportions you see differnt colours)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
133
Q

What is rods sensitivity light

A

They’re very sentimental to Light ( they fire action potentials in dim light)
This is because many rods join one neuron, so many weak generator potentials combine to reach the threshold and trigger action potentials

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
134
Q

How sensitive are cones to light

A

Less sensitive than rods
(They only fire action potentials in bright light )
This is because one cone joined one neurons, so it takes more light to reach the threshold and trigger an action potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
135
Q

What is rods visual acuity

A

Low visual acuity because many rods join same neuron, which means light form two points close together can’t be told apart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
136
Q

What is cones visual acuity

A

High
As cones are close togetehr and one cones joined one neuron
When light form two points hits two cones, two action potentials go to the brain
So you can distinguish two points that are close together as two separate points

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
137
Q

What the stimulus for a mechanoreceptor

A

Physical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
138
Q

Be able to label pacinian corpuscle

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
139
Q

Why is pacinian corpuscle a primary receptor

A

It’s Stimulated directly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
140
Q

What do pacinian corpuscles respond to changes in

A

Mechanical pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
141
Q

What happens when a pacinian corpuscle is pressed

A

When pressed, the change in pressure on
the membranes passes to the core and
causes increased permeabiltiy to sodium
ions Na+ causing depolarisation leading to
a generator potential. If this exceeds
the threshold then a nerve impulse is
generated.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
142
Q

T or f
Slow pressure changes or prolonged pressure does not cause a response

A

T

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
143
Q

t or f
Pacinian corpuscle is a transducer

A

T

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
144
Q

What is a transducer

A

Converts one from or energy into another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
145
Q

What do pacinian corpuscles convert what energy to what energy

A

kinetic to electrical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
146
Q

How do stretch mediated sodium channel proteins work

A

When pressure is applied the membrane
around the neurone becomes stretched.

This stretching widens the sodium channels
and sodium ions diffuse into the neurone.
• The influx of the sodium ions changes the
potential of the membrane ( it has become
depolarised) thus making a generator
potential.
• The generator potential therefore starts an
action potential-nerve impulse.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
147
Q

Where are the receptors in the eye found

A

The inner layer of the retina

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
148
Q

What are the 2 types of receptors in the eye

A

Rods
Cones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
149
Q

How does receptors in the eye act as a transducer

A

Converts light energy to electrical. Energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
150
Q

Check labelling of fovea, optic nerve, retina of eye

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
151
Q

Where are the nerve imupuses sent along optic never to

A

The brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
152
Q

What photosensitive chemical do rods contain and where

A

Rhodopsin in the outer segment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
153
Q

What type of photosensitive chemical do cones contain and where

A

Iodopsin in outer segment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
154
Q

What must light pass through to reach rods and cones

A

Other structures
Eg. Bipolar cells, blood vessels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
155
Q

Rhodopsin and iodopsin pigment get …… by light.
Is it reverisble

A

Bleaches
Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
156
Q

After bleaching rhodopsin regenerates fast ro slow

A

Slowly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
157
Q

After bleaching iodopsin regenerates fast ro slow

A

Fast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
158
Q

What happens when rhodopsin or iodopsin is stimulated

A

Changes shape and a transmitter substance is released to bipolar cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
159
Q

How many and where are rods in the retina

A

120 million in all parts except the fovea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
160
Q

What are rods used for

A

Night vision

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
161
Q

What do rods repsond to

A

Low light elevens and are used to see in dim light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
162
Q

What does light cause rhodopsin to do

A

Change shape
Splits into opsin and retinal
Transmitter is sent to bipolar cells
Bipolar cells are neurons wich transmit impulse to next cell layer

163
Q

T or f
Rod cells produce transmitter when not stimulate and stop producing when stimulated

A

T

164
Q

How many rods connect to each bipolar cell
So is it Moore likely to be activated by bright light or dim light

A

Several
Dim

165
Q

Rhodopsin is very stable in ……..
In …….. it breaks down quickly

A

The dark
Strong light

166
Q

How many cones are in the retina and where

A

5-6 million
All parts of retina especially in fovea

167
Q

Why does the fovea have high visual acuity

A

In fovea the Sa is more thinner
Cone cells are very small
So this area has high visual acuity

168
Q

What 2 things can the fovea area be described as being

A

High visual acuity
Better resolution

169
Q

What are cones used for

A

Colour vision in high intensity light

170
Q

What is the pigment in cones only broken down by

A

High light intensity

171
Q

What is colourblindness due to

A

Lack of comes responding to some wavelengths

172
Q

They heart is myogenic
What does this mean

A

When removed form the body it continues to beat

173
Q

What does the heart need to be

A

Regulated and controlled

174
Q

What is the SA under control of

A

The brain
( the sympathetic and parasympathetic)

175
Q

What is heartbeat regulated by

A

Specialised muscle cells called pacemakers and a tract of conducting purkyne fibres

176
Q

What does the pacemaker do

A

Initiates the cardiac cycle by spontaneously generating action potentials in the atria, spreading to the ventricles and stetting a basic heart rhythm

177
Q

What are the basic rhythms in the heart regulated according to

A

Demand

178
Q

What 2 things are heartbeats controlled by

A

Hormones and nerves

179
Q

What 2 hormones control the heat beat
And how do they act in relation to each other

A

Adrenaline
Noradrenaline

Act antagonistically

180
Q

What 2 nerve systems control the heart beat

And how do they act in relation to each other

A

Parasympathetic
Sympathetic

Act antagnotically

181
Q

Sympathetic stimulation via the cardiac muscle
Is it the predominant influence

A

Yes

182
Q

What does the parasympathetic nervous systems do for heart beat

A

Inhibits effectors
Controls actions under resting conditions
Slows down activity
Conserves energy

183
Q

What does the sympathetic nervous system do

A

Stimulates effectors
Controls conditions under stress of activity
Speeds us up ( fight / flight)

184
Q

What is the area of the brain that controls heart rate

A

Medulla oblongata

185
Q

What are the 2 parts of the medulla oblongata in heart beat

A

1, centre linked to sinoatrial node that inc heart rate via the sympathetic NS
2. A centre linked to the sinoatrual that dec, heart rate via the parasympathetic NS (Vegus nerve)

186
Q

What 4 things effect cardiovascular centre in medulla

And what does this effect

A
  1. Pressure receptors I’m aortic and carotid bodies
  2. Chemoreceptors in aortic and carotid bodes
  3. Temperature receptors in muscles
  4. Stretch receptors in muscles

Effects parasympathetic and sympathetic to bring about an effect

187
Q

How do receptors respond to pressure changes in the blood ( heart rate)

A

Pressure receptors in wall of aorta and acrid artery send messages via sympathetic nervous system if blood pressure is slow and through PSNS when high

188
Q

How do receptors repsond yo chemical chmages in the blood ( heart. Rate)

A

Low O2 means increased co2 and reduced PH. Detected by chemoreceptors in wall of aorta and carotid artery, heart rate increase via SNS. Removal of CO2 increasesPHand heart rate reduced via PSNS

189
Q

The heart can contract and relax without receiving signals form nerves.
So what is the heart called

A

Myogenic

190
Q

How is the regular heartbeat contorted

A

1) Sino atrial mode (SAN)
2) SAN sends out regular waves of regular activity to the atrial walls
3) so right and left atria to contract at the same time
4) waves of electrical activity are transferred form the SAN to the atrioventricular node ( AVN)
5) AVN is responsible for passing the waves of electrical activity on to the bundle of his (there is a slight delay before AVN reacts )
6) the bundle of his conducts waves of electrical activity between the ventricles to the apex of the heart . The bundle splits into finer muscle fibres In the right and left ventricles called purkyne tissue
7) these carry waves of electrical activity into keuclat walls of R and L ventricles, causing them to contract simultaneously from bottom up

191
Q

Where is the San

A

Wall of the right atrium

192
Q

What does the SAN do

A

Like a pacemaker
Sets the rhythm of the heartbeat by sending regular waves of electrical activity to atrial walls

193
Q

What prevents the waves of electrical activity form being passed directly from the atria to the ventricles

A

A band of non conducting collagen tissue

194
Q

What is the AVN responsible for

A

Passing the waves of electrical, activity on to the bundle of his

195
Q

Why is there a slight delay after the AVN

A

To make sure the atria have emptied before the ventricles contact

196
Q

What is the rate at which the SAN fires controlled by

A

Unconsciously controlled by the medulla oblongata in the brain

197
Q

Why do animals need to alter their heart rate

A

Respond to internal stimuli

198
Q

What are stimuli that effect heart rate detected by

A

Reassure receptors and chemical receptors

199
Q

What are pressure receptors for heart rate called. And what are they stimulated by

A

Pressure receptors ( called baroreceptors) in the aorta and the carotid artieries. Stimulated by high and low blood pressure

200
Q

What are chemical receptors for heart rate called. And what are they stimulated by

A

Chemcial receptors called chemoreceptors in the aorta, the carotid artaeries and In the medulla.
They monitor the oxygen level in the blood and also carbon dioxide and ph

201
Q

Electrical impulse from receptors are sent to the mudulla along the …….. neurons

A

Sensory

202
Q

What system does medulla send info to SAN along

A

Sympathetic or parasympathetic

203
Q

What NS are sympathetic or parasympathetic part of

A

autonomic

204
Q

How does the heart repsond ot high blood pressure

A

Receptor - Baroreceptors detect Hugh blood pressure
Impulses are sent to the medulla, which sends impulses along the parasympathetic neurons. There secrete acetylcholine ( a neurotrwmitter) which binds to the receptors of the SAN
Heart rate slows down to reduce blood pressure back to normal

205
Q

How does the heart repsond to low blood pressure

A

receptors - baroreceptors detect low blood pressure
Impulses are sent to the medulla, which sends impulses along the sympathic neurons. These secrete noradrenaline ( a neurotranimtter( which binds to receptors of the SAN)
Herat rate speeds up to increases blood pressure back to normal

206
Q

How does the heart repsond ot high blood O2, low CO2, high PH

A

Chemoreceptors detected chemical changes in the blood
Impulses are sent to the medulla, which sends impulses along parasympathetic neurons
These secrete acetylcholine which binds to receptors on the SAN
Heart rate decreases to return O2, co2 and Oh levels back to normal

207
Q

How does the heart repsond To low blood O2, high CO2 or low PH levels

A

Chemoreceptors detect chemical changes in the blood
impulses are sent to the medulla, which sends impulses also sympathetic neurons. These secrete noradrenalin which binds other the SAN
Heart rate increases to return O2! CO2 and PH back to normal

208
Q

Describe a Schwann cell

A

Surrounds axon by wrapping around many times, protecting , provides electrical insulation . Can undergo phagocytosis to fight infection and nerve Regeneratiom

209
Q

Describe a cell body

A

Nucleolus, RER for proteins and neurotransmitter synthesis

210
Q

Describe dendrons

A

Carrys nerve impulses towards cell body

211
Q

Desicbe the axon

A

Single long fibre , carries nerve impulses away from cell body

212
Q

Describe the myelin sheath

A

Forms covering of axon and made of membrane of the Schwann cell. Rich is lipid known as mylelin. Can be myleinated or unmylinated, myelinated neurons transmitted nerve impulses faster than

213
Q

Desicbe the nodes of ranvier

A

Gaps between Schwann cells ( where there is no myelin sheath) gaps 2-3 um , occur every 1-4 mm

214
Q

What is a nerve impulse

A

Self propagating wave of electrical disturbance that travels along the surface of the axon memebrane .
It isn’t an electrical current , it’s a temporary reversal of the electrical potential difference across the axon memebrane

215
Q

What is the temporary reversal between in a nervous impulse

A

2 states called resting and action potential

216
Q

The inside of the axon is ……. Changed relatively to the outside

A

Negatively

217
Q

What is the resting potential around

A

-65 mV

218
Q

What is potential difference established by

A

1) Na + ions AT out of axon by Na-K pump
2) K+ ions AT into axon by Na-K pump
3) AT of Na ions is greater than K ions (3Na out, 2K in)
4) Na and K both positive , more Na in tissue fluid around axon , more K in cytoplasm so a chemical gradient
5) Na diffuses back naturally into axon , K + out , but Na gates mainly shut and K mainly open
6) axon 100x more permeable to K ions - inc PD
7) electrical gradient as K+ leave outside - outside axon becomes more positively changed
8)further K+ movement become hard as they are attracted to the negative axon so prevents them movement out
9) equilibrium extravlished which chemical and electrical gradient balances

219
Q

Desicbe the action potential.

A

Stimulus received by receptor or nerve ending . It’s energy causes a temporary reversal of the change on the axon memebrane
Results is a negatively changed inside memebrane becoming +40mv

220
Q

What is the memebrane said to be during action potential

A

Depolarised

221
Q

What are the basic points of action potential.

A

1) Na+ gated channels open
2) Na+ flood into axon
3) potential differnce reversed
4) Na+ gates closed
5) K+ gates channels open
6) K+ flood out of axon
7) inside axon returns to negative
8) resting potential restored

222
Q

Make sure you understand potential differences across memebrane graphs
Be able to label

A
223
Q

Explain action potential in detail

A

1)At resting potential some K voltage-gated channels are open but Na channels are closed.
2) Energy of stimulus causes some Na voltage channel in the axon membrane to open and therefore sodium ions diffuse into the axon through these channels, along their electrochemical gradient. As they are + charged, they trigger a reversal in the PD across the membrane.
3) As the Na+ diffuse into the axon, more Na channels open, increasing the Na+ influx by diffusion .
4) Once the action potential of around +40mV has been established, the voltage gates on the sodium ion channels close and the voltage gates on the K+ channels open.
5) With some K voltage-gated channels open, the electrical gradient that was preventing further outward movement of K ions is now reversed, causing more K ion channels to open. This means more K ions diffuse out, causing repolarisation of the axon.
6) The outward diffusion of these K ions causes a temporary overshoot of the electrical gradient, with the inside of the axon being more negative (relative to the outside) than usual (hyperpolarisation)
7) The gates on the K+ channels now close and the activities of the Na-K pumps once again cause
Na+ to be pumped out and K+ to be pumped in. The resting potential of -65mV is re-established
and the axon is said to be repolarised.

224
Q

What is hyperpolarisation

A

Outward diffusion of K ions cause a temporary overshoot of the electrical gradient.
The inside of the axon being more Negative relative to the outside than usual

225
Q

What happens in an unmylenated neuron

A

Localised electrical current are set up and the action potential is propagated along the neuron

226
Q

Descirbe a myelinated neuron

A

Neuron is encased in a fatty myelin sheath
The Sheath of one cell meets the next - here the axon is unprotected

227
Q

What happens at the unprotected areas of the axon in a mylenated neuron

A

Voltage gated Na+ channels of myelinated neurons are confined to these spots
( nodes of ranvier h

228
Q

What describes the movement from one node of ranvier to another

A

Saltatory conduction

229
Q

Desicribe saltatory conduction

A

In rush of sodium ions at one node creates enough depolarisation to reach the threshold of the next
Action potential’ jumps ‘ from one node to the next

230
Q

Advantages of saltatory conduction

A

Much faster propagation of the nerve impulse that is possible in unmyleinated neurons

231
Q

What factors effect speed of an action potential

A

1.the mylenated neurons
2. Diameter of axon
3. Temperature

232
Q

How does diameter of the axon effect speed of the AP

A

Greater the diameter the faster the conductance due to less leakage

233
Q

How does temp effect speed of AP

A

Higher temp = faster nerve impulse ( rate of diffusion is faster) , enzyme activity is faster eg. ATP

234
Q

What is the all or nothing principle

A

AP only happens if the stimulus reaches a threshold value
- stimulus strong enough to cause an
it’s all or nothing as when it starts it travels to the synapse
The Ap is always the same size
The ap is the same size all the way along the axon
The transmission of the ap along the axon is the nerve impulse

235
Q

What is rhe refractory period

A

Time after depolarisation where no new ap can start

236
Q

Why is the refractory period needed

A

To restore the proteins of the voltage sensitive ion channels to their original resting conditions
- na+ channels Cannot be opened as it can’t be depolarised again

Also needed:
Ap travels in one directions
Produced a discrete impulse
Limits frequency of impulse

237
Q

How does the size of stimulus detected effect ap

A

The number of impulses in a given time - the larger the stimulus the more impulses generated
By having neurons with differnt threshold values - the brain interpreters the number and type of neuron and thereby determine its size

238
Q

In a neurons resting state - the outside of the membrane is ….. positively changed than the inside.
Why

A

More
As there are more positive ions outside the cell than inside

239
Q

There is a differnce in charge across. The axon memebrane.
So what is it described as

A

Being polarised
( called a potential differnce or voltage across it)

240
Q

What is the voltage across the memebrane when it’s at rest. Called

A

Resting potential

241
Q

Roughly what is resting potential

A

-65mV

242
Q

What is the resting potential created and maintained by

A

Sodium potassium pumps and potassium ion channels in the neurons memebrane

243
Q

Describe how a resting potential is mainliner / created

A

1) sodium potassium pump moves sodium ions out of the neuron but the memebrane ist permeable to sodium ions so they can’t diffuse back in . This creates a sodium ion electrochemical gradient because there are more positive sodium ions outside the cell than inside

2) the sodium potassium pump also. Move potassium ions in to the neuron, but the membrane is permeable go potassium ions so they diffuse back out through potassium ion channels

3) this makes the outside of the cell positivity changed compared to the inside

244
Q

What does a stimulus trigger in an axon

A

Sodium ion channels to open , if the stimulus is big enough it will trigger a rapid change in potential differnce called an action potential

245
Q

What are the the key changed in potential differnce during an action potential on the Pd-time graph

A
  1. Stimulus
  2. Depolarisation
  3. Repolarisation
  4. Hyperpolaistion
  5. Resting potential
246
Q

How does the membrane of an axon change when it detected a stimulus

A

Stimulus excited the neuron cell membrane causing sodium ion channels ot open
The membrane becomes more permeable to sodium, so sodium ions diffuse into the neuron down the sodium ion electrochemical gradient, thus makes the inside of the neuron less negative

247
Q

How does the membrane of the axon change during depolarisation

A

If the potential differnce reaches the threshold, more sodium ion channels open. More sodium ions diffuse rapidly into the neuron

248
Q

How does the membrane of the axon change during repolarisation

A

At a potential differnce of around + 30mV the sodium ion channels close and potassium ion channels open. The memebrane is more permeable to potassium so potassium ions diffuse out of the neurone down the potassium ion conc gradient . This starts to get the membrane back to resting potential

249
Q

How does the membrane of the axon change during hyperpolarisaton

A

Potassium ion channels are slow to close so there’s a slight overshoot where too many potassium ions diffuse out to the neurone. The potential differnce becomes more negative then the resting potential

250
Q

How does the membrane of the axon change during re reaching resting potential

A

The ion channels are reset. The sodium potassium pump retunes the membrane to its resting potential and maintains it until the membranes excited by another stimulus

251
Q

After an action potential can the neuron cell membrane be excited again
And why

A

Not immediately
Because the ion channels are recovering and they can’t be made it open -

252
Q

When are the sodium ion channels closed

A

During repolarisation

253
Q

When are potassium ion channels closed

A

During hyperpolarisation

254
Q

What is the period of recovery for the axon memebrane called

A

Refractory period

255
Q

When an action potential happens what happens to some of the sodium ions that enter

A

They diffuse sideways

256
Q

What effect does sodium ions diffusing sideways during action potential have

A

Causes sodium ion channels in the next region of the neuron to open and sodium ions diffuse into that part - causing a wave of depolarisation to travel along the neuron

257
Q

The wave moves away from part of the membrane in the ………
Why

A

Refractory period
These parts can’t fire an action potential

258
Q

The refractory period acts as a time delay form one action potential to the next
What does this mean for AP:

A

1) AP don’t overlap, but pass along as discrete separate impulses
2) there’s a limit to the frequency at which the nerve impulses can be transmitted
3) action potentials are unidirectional ( only travel in one direction)

259
Q

Once a threshold is reached an action potential will always fire the same change in voltage no matter how big the stimulus is
And if it’s not reached the ap won’t be fired

What is this known as

A

All of nothing principle

260
Q

A bigger stimulus won’t cause a bigger action potential, what will it cause

A

Them to fire more frequently

261
Q

What does it mean if neurons are myelinated

A

They have a myelin sheath

262
Q

What is the myelin sheath

A

An electrical insulator

263
Q

What is the myelin sheath made form

A

Schwann cells

264
Q

In a myelinated neurons, where does depolarisation only occur

And how does this still allow a wave of depolarisation

A

At the nodes of ranvier

The neurons cytoplasm conducts enough electrical charge to depolarise the next node, so the impulse jumps form node to node

265
Q

Is Saltatory conduction fast or slow

A

Very fast

266
Q

How does an impulse travel in a non myelinated neuron

A

A wave along the whole length of the axon memebrane ( this is slower)

267
Q

Why are action potentials conducted quicker along axons with bigger diameter

A

Less resistance to the flow of ions than in the cytoplasm of a smaller axon. With less resistance, depolarisation reaches other parts of the neurone cell memebrane quicker

268
Q

How does temp effect speed of conduction

A

Increases as temp increase as ions diffuse faster,
Only increases up to around 40°c then after that proteins begin to denature and speed decreaes

269
Q

What is a synapse

A

A junction between a neuron and another neuron
Or between neurone and an effector

270
Q

The tiny gap between the cells at the synapse is called….

A

The synaptic cleft

271
Q

What is the neurone before the synapse called

A

Presynaptic neuron

272
Q

The presynaptic neurone has a swelling called a …

A

synaptic knob

273
Q

What does the synaptic knob contain

A

Synaptic vesicles filled with chemicals called neurotransmitters

274
Q

What happens when an action potential reaches the end of the neuron

A

It causes neurotransmitters to be released into the synaptic cleft
They diffuse across to the postsynaptic memebrane and bind to specific receptors

275
Q

What is the neurone after the synapse xallled

A

Postsynaptic memebrane

276
Q

When the neurotramitter bind to the receptors ( in a synapses what might happen

A

Might trigger an action potential in a neurons
Cause muscle contraction in muscle cell
Hormone to be secreted from a gland cell

277
Q

Where are receptors only found in synapses

A

On the postsynaptic membrane

278
Q

What effect does receptors only being on postsynaptic membranes have

A

make sure impulses are unidirectional- they only go in one direction

279
Q

Why are neurotramitters removed from the cleft

A

So response doesn’t keep happening

280
Q

How are neurotransmitters removed from the cleft

A

They are taken back into the presynaptic neurone or they are broken down by enzymes

281
Q

Examples of neurotransmitters

A

Acetylcholine (ACh)
Noradrenaline

282
Q

What are synapses that use acetylcholine called

A

Cholinergic synapses

283
Q

How is a nerve impulse transmitted a cholinergic synapse

A

1) an action potential arrives at the synaptic knob of the presynaptic neurone
2) the action potential stimulates voltage gated calcium ion channels in the presynaptic neurone to open
3) calcium ions diffuse into the synaptic knob
4) influx of calcium ions into the synaptic knob cause the synaptic vesicles to move to the presynaptic membrane. They then fuse with the presynaptic membrane
5) the vesicles release the neurotransmitter acetylcholine into the synaptic cleft - called exocytosis
6) ACh diffuse across the synaptic cleft and bind to specific cholinergic receptors on the postsynaptic membrane
7) this causes sodium ion channels in the postsynaptic neurons to open
8) the influx of sodium ions into the post synaptic memebrane causes depolarisation. An AP on the postsynaptic membrane is generated if the threshold is reached
9) ACh is removed form the synaptic cleft so the response doesn’t keep happening,

284
Q

How is ACh removed form the synaptic cleft

A

Brocken down by an enzyme called acetylcholinesterase (AChE) and the products are re absorbed by the presynaptic neuron and used other make more ACh

285
Q

What happens to the calcium ions that diffuse into the synaptic knob

A

They are pumped out afterwards by AT

286
Q

What 3 things can neurotransmitters be

A

Excitatory
Inhibitory
Both

287
Q

What is an excitatory neurotransmitter

A

Depolarise the postsynaptic membrane, making it fire and AP if the threshold is reached.

288
Q

Give an example of excitatory neurotransmitter

A

Acetylcholine
At the cholinergic synapse in the CNS - it binds to cholinergic receptors to cause AP in the postsynaptic memebrane and at neuromuscular junctions

289
Q

What is a inhibitory neurotransmitter

A

Hyperpolarise the postsynaptic membrane ( make the potential differnce more negative) preventing it from firing an AP

290
Q

Examples of an inhibitory neurotransmitters

A

Acetylcholine is an inhibitory neurotransmitter at cholinergic synapses in the heart. When it binds to receptors here, it can cause. Potassium ion channels to open on the postsynaptic membrane , hyperpolarising it

291
Q

What happens when a stimulus is weak in terms of neurotransmitter

A

if weak only small amounts of neurotransmitters will be released from a neurone into the synaptic cleft. This might not be enough to excite the postsynaptic membrane to the threshold level and stimulate an AP

292
Q

What is summation (neurotramitters)

A

Where the effect of neurotransmitter released form many neurons ( or one neurone that’s stimulated a lot in a short period of time) is added together l there are two types of summation

293
Q

What are the 2 types of summation

A

Spatial summation
Temporal summation

294
Q

What spatial summation

A

1) sometimes many neurone connect to one neurone
2j the small amount of neurotransmitter released from, each of those neurons can be enough altogether to reach the threshold in the postsynaptic neurone and trigger an AP
3) if some neurons release an inhibitory neurotramitters then the total effect of all the neurotramitters might be no AP

295
Q

If more Inhibitpry neurotramitters are realised then excitatory neurotransmitter what happens

A

No AP

296
Q

What is temporal summation

A

Where two or more nerve impulses arrive in quick, succession form the same presynaptic neurone.
This makes AP more likely because more neurotramitters is released into the synaptic cleft

297
Q

What does summation do

A

Means synapses accurately process information , finely tuning the response

298
Q

What is a synapse between motorr neurons and muscle cells called

A

Neuromuscular junction

299
Q

What neurotramitters does neuromuscular junctions use

A

Acetylcholine

300
Q

What does ACh bind to at neuromuscular junctions

A

Cholinergic receptors called
Nicotinic cholinergic receptors

301
Q

What are the differences between neuromuscular junctions and cholinergic synapse

A
  • the postsynaptic membrane has lots of folds that from clefts m these clefts store the enzyme that breaks down ACh
  • the postsynaptic memebrane has more receptors than other synapses
  • ACh is always excitatory at neuromuscular junction . So when a motor neurone fires an AP, it triggers a response in a muscle cell. This isn’t always the case for synapse between two neurons
302
Q

What enzyme breaks down ACh

A

Acetylcholinesterase

303
Q

What 5 ways can drugs effect synaptic transmission

A

1) Soem drugs are the same shape as neurotramitters so they mimic their actions at receptors
2) block receptors
3) inhibits enzymes that break down neurotramitters
4) stimulate the release of neurotramitters
5) inhibit release of neurotramitters

304
Q

How do drugs that are the same shape of neurotramitters effect synaptic tramission

A

They mimic their actions at receptors
These drugs are called agonists
This means more receptors are activated

305
Q

How do drugs that block receptor effect synaptic tramission

A

Block receptors so they can’t be activated by neurotransmitters ( these are called antagonists) this means fewer receptors can be activated
This results in the muscle being paralysed

306
Q

How do drugs that inhibit enzymes that break down neurotramitters effect synaptic tramission

A

This means there are more neurotramitters in the synaptic cleft to bind to receptors and they’re there for longer
Lead to loss of muscles control

307
Q

How do drugs that stimulate the release of neurotramitters effect synaptic tramission

A

More receptors are activated

308
Q

How do drugs that inhibit the release of neurotramitters effect synaptic tramission

A

Fewer receptors are activated

309
Q

What are synapses , what are the size

A

Gaps between neurons
20z30nm

310
Q

What are the functions of synapses

A

A single impulse can be transmitted to a number of differnt neurons creating simultaneous responses

A number of impulses combined at a synapse allowing stimulus form differnt receptors to interact to form a single response

311
Q

What are the steps of synaptic transmission

A

1) incoming AP, depolarisation in synaptic knob, ca2+ channels open and flood into knob
2) influx Ca2+ causes synaptic vesicles to fuse to presynaptic memebrane and release NT into cleft
3) NT( acetylcholine) released cleft, diffuse, AC bind to receptors on NA+ channels which causes a conformational change ( shape) and NA+ channels open.
4) NA+ to flood in causing depolarisation, new AP sent along axon of postsynaptic neurone

312
Q

What happens for AC after synaptic transmission

A

ACase breaks yo acetylcholine into acetylcholine ( Ethanoic acid; and choline
So sodium ions channels close
The bits diffuse back across cleft into the presynaptic neurone allowing NT to be recycled

313
Q

What enzyme breaks down acetylcholine

A

Acetylcholinesterase

314
Q

Why is AC broken down

A

Beacuse if it’s not broken down it could allow it to be continuously generating new AP.

315
Q

How is acetylcholine remade

A

ATP released by mitrochondia is used to recombined acetylene and choline thus recycling the acetylcholine
Thus us stored in synaptic vesicles for future use

316
Q

Where can more acetylcholine be made

A

in SER

317
Q

2 features of the synapse

A

Unidirectional
Summation

318
Q

What does it mean that synapses are unidirectional

A

Synapses can only travel in one direction:
from the presynaptic neurone to the
postsynaptic neurone

319
Q

What are the two types of summation

A

Spatial
Temporal

320
Q

What is spatial summation

A

A number of different presynaptic neurones
together release enough neurotransmitter to
exceed the threshold value of the postsynaptic
neurone. Together they therefore trigger a new
action potential

321
Q

What is temporal summation

A

A single presynaptic neurone releases
neurotransmitter many times over a short period.
If the total amount exceeds the threshold value
of the postsynaptic neurone, then a new action
potential is triggered

322
Q

Explain inhibition of synaptic transmission

A

On the postsynaptic mebrane, some synapses the protein channels carrying Cl- ions can be made to open
Leads to inward diffusion of Cl- ions making the inside of the the postsynaptic mebrane even more negative than resting potential (hyperpolarisation (
So less likely that a new AP will be created

323
Q

What type of muscle can you move

A

Skeletal muscle

324
Q

Skeletal muscle are attached to ……. By….

A

Bones
Tendons

325
Q

What attach bones to other bones and holds them together

A

Ligaments

326
Q

What moves bones at a joint

A

Pair of skeletal muscles contract and relax to move bones at a joint

327
Q

How do the bones of the skeleton act as levers for muscles

A

They are incompressible ( rigid)
This gives muscles something to pull against

328
Q

What are muscles that work together to pull a bone called

A

Antagonistic pair

329
Q

In an antagonistic muscle pair
What is the contracting and relaxing msucle called

A

The contracting muscle is called the agonist
The relaxing muscle is called the antagonist

330
Q

Why do muscles only work in pairs

A

They can only pull when they contract - they can’t push

331
Q

Desicbe how your biceps and triceps work antagonisticall

A

When biceps contracts (agonist) the triceps relaxes ( antagonist )
This pulls the bones so your arm bends at the elbow

When your tricep contracts ( agonist ) , the bicep relaxes relaxes ( antagonist) this pulls the bones so your arm straightens as the elbow

332
Q

What are muscles stimulated to contract by

A

Neurons

333
Q

What is skeletal muscle made up of

A

Large bundle of long cells called muscle fibres

334
Q

What is the cell memebrane of muscle fibre cells called

A

SarcoLemma

335
Q

What is the msucle cells cytoplasm called

A

Sarcoplasm

336
Q

What do bits of the sarcolemma do in msucle cells

A

Fold inwards across muscle fibres and stick into the sarcoplasm

337
Q

What are folds in the sarcolemma called

A

Transverse tubules

338
Q

What do transverse tubules do

A

Help spread electrical impulses throughout the sarcoplasm

339
Q

What stores and releases calcium ions needed for msucle contraction r

A

Sarcoplasmic reticulum

340
Q

Features of msucle fibre

A

1) lots of mitochondria to provide the ATP that’s needed for muscle contraction
2) multinucleate (contain many nuclei)
3) lots of myofibrils

341
Q

What are myofibrils

A

Long cylindrical organelles that are highly specialised for contraction

342
Q

What do myofibrils contain and what do they don

A

Contain bundles of thick and thin myofilaments that move past each other to make muscles contract

343
Q

What are thick myofilaments made of

A

Protein myosin

344
Q

What are thin myofilaments made of

A

The protein actin

345
Q

What would you see if you look at myofibril under an electron microscope

A

A pattern of alternating dark and light bands

346
Q

What causes the dark bands in an electron microscope of myofibril

A

Dark bands contain the thick myosin filaments and some overlapping then actin filaments _ these are called A-bands

347
Q

What causes the light bands in an electron microscope of myofibril

A

Light bands contain thin actin filaments only - these are called I-bands

348
Q

A myofibril is made up of many short units called …..

A

Sacromeres

349
Q

What are the ends of each sacromere marked with

A

A z line

350
Q

What is in the middle of each sacromere

A

M-line
The M-line is the middle of the myosin filaments

351
Q

What is around the M-line in a muscle

A

The H-zone

352
Q

What does the Hzone contain

A

Only myosin filaments

353
Q

The myofilaments don’t contract
What actually happens to make a msucle condtarxt

A

Myosin and actin filaments slice over one another to make the sacromeres contract

354
Q

The simultaneous contraction of lots of sacromeres means …..

A

The myofibrils and muscle fibres contract

355
Q

Do sacromere return to their origional length as the muscle relaxes

A

Yes

356
Q

What theory explains muscle contraction

A

Sliding filament theory

357
Q

Describe what happens to the A band, I band and H zone during msucle cosntaction

A

Aband stays the same length
I band gets shorter
H zone gets shorter

358
Q

What are the 3 types of muscles

A

Cardiac
Smooth or involuntary
Striated or skeletal

359
Q

What is smooth or involuntary muscles

A

Controlled by automatic NS

360
Q

What is striated or skeletal

A

Under conscious control, oftern attached to bone - enables movement

361
Q

Functions of the skeleton

A

Support - forms shape of body
Protection
Movement

362
Q

What are bones joined by

A

Ligaments

363
Q

How are muscles joined to bones

A

By tendons

364
Q

Why do muscles work in groups

A

They can only contract So they work as antagonistic pairs

365
Q

In an antagonistic muscle pair,
What is the contractinfand relaxed pair called

A

Contracting - agonist
antagonist - relaxed

366
Q

What are the 2 types of skeletal muscles fibres

A

Slow twitch
Fast twitch

367
Q

Describe slow twitch fibres

A

Contract slowly, provide less powerful contractions over a long period of time, adapted from enduracne

368
Q

Where are slow twitch fire we found

A

Postural muscles such as calf

369
Q

What are aerobic fibres suited for ( respiration(

A

Aerobic

370
Q

What are contained in slow twitch fibres

A

Large stores of myoglobin for O2 storage
Glycogen for energy, lots of mitchorcondia to produce ATP , rich blood supply to deliver O2 and glucose

371
Q

Descirbe fast twitch fibres

A

Contract rapidly and produce powerful contractions for a short period of time, quoted from intense exercise

372
Q

Where a fast twitch fibres commonly found

A

Biceps

373
Q

What do fast twitch fibres contain

A

They are thicker with more myosin filaments
Contain lots of enzymes involved in aerobic respiration. Contain a store of phosphocreatine to provide energy for muscle contractions

374
Q

What is it called where a motor neurone connects to a muscle

A

Motor end plate

375
Q

What tissues is a muscle composed of

A

Muscle tissue, connective tissue

376
Q

What is muscle tissue composed of

A

Muscle fibres

377
Q

What is each muscle fibre packed with

A

Organelles called myofibrils

378
Q

What are myofibrils composed of

A

Mainly of two muscle filaments called actin and myosin

379
Q

What is a functional unit of a myofibril called

A

Sacromere

380
Q

What is thicker actin or myosin

A

Myosin

381
Q

What is the dark section of a muscle called

A

Anisotropic

382
Q

What is the light section of a msucle called

A

Isotopic

383
Q

Describe actin

A

Main protein in think filaments.
Individual actin molecules twist around one another to from a filament
The two are reinforced by a protein called tropomyosin.
Attached to each tropomyosin are troponin complexes made of 3 polypeptides

384
Q

Describe myosin filaments

A

Composed of polypeptide chains twisted around each other with 2 globular heads on the end, many of these polypeptides intertwined to from thick filaments

385
Q

Describe the differences between neuromuscular junctions and choloergenic synapses

A

1) NJ are only excitatory , C can be excitatory or inhibitory
2) NJ are neurons to muscles , C can be neurons to neurons or neurons or effectors
3) NJ only motor Neuroms, C motor, sensory , intermediate
4) NJ the ap ends here, C ap may be produced along the next neurone
5) NJ acetylcholine binds to receptors on memebrane of muscle fibre, C the acetyl choline binds to receptors of Na+ ion channels

386
Q

Desicbe how an AP can cause a muscle contraction

A

1) AP arrives at motor plate , causes release of acetyl choline into plasma membrane of muscle fibre ( called sarcolemma). Causing depolarisation to spread over sacrolemma and into muscle fibre infoodimfs ( T - Tubules) , this causes a release of Ca 2+ ions from sacroplasmic reticulum

2) ca2+ ions attach to troponin complexes and causes a change in shape wich pulls the tropomyosin out of the e myosin binding sites

3) myosin attaches to the actin, ATP- ADP+ Pi, this releases energy which provided energy for contraction / power stroke. The energy released from ATP causes myosin head to bend, pulling actin along.

4) myosin, locked onto actin contracts - pulling the actin filament. The 2 filament slide past each other

5) ATP causes release of myosin head from actin by breaking the actin myosin cross bridge
( the myosin head detaches from actin filament after it has moved)

6) the myosin head then reattaches to a different binding site further along the actin filament. A new actin myosin cross bridge is formed and the cycle repeats
Many cross bridges form a break very rapidly pulling the actin filaments along

387
Q

After ATP causes release of myosin head in muscle contraction, if the Ca 2+ remains what happens

A

the cycle repeated and muscle contraction continues

388
Q

After ATP causes release of myosin head in muscle contraction, if the ca 2+ is returned to sacroplamic reticulum what happens

A

The muscle relaxers

389
Q

How is ATP supply maintained

A

1) aerobic respiration in muscle cells , this needs a supply of respitory substrate and o2
2) anaerobic respiration - this also produced lactate and can lead to msucle fatigue and cramp
3) creatinine phosphate - a chemcial present in mucosa cells can donate its phosphate to recharge ADP back toATO

390
Q

What is the period between individual contractions called

A

Refractory period

391
Q

What is summation in msucle contractions

A

Released impulses - leading to enhanced contractions

392
Q

What is tetanus - muscle contractions

A

Series of quick impulses leading to a state of maximum contraction . The msucle would eventually fatigue

393
Q

Desicbe the features of a myosin filament

A

globular heads that are hinged, so they can move back and forth.
Each myosin head has a binding site for actin and a binding site for ATP

394
Q

Describe the features of actin filaments

A

have binding sites for myosin heads , called actin-myosin binding sites.
another protein called tropomyosin is found between actin filaments, it helps myofilamentd move past each other

395
Q

In a resting muscle, why can’t myofilaments slide past each other

A

the actin myosin binding site is blocked by tropomyosin
So the myosin heads can’t bind to the actin- myosin bidning site on the acting filaments

396
Q

What is the bond between a myosin head and an actin filaments called

A

Actin-myosin cross bridge

397
Q

What happens when a msucle stops being stimulated

A

Calcium ions leave their binding sites and are moved by active transport beaks into the sarcoplasmic reticulum ( this needed ATP.)
This causes tropomyosin molecule to move back. So they block the actin-myosin bidning sites again
Muscles arnt contracted because no myosin heads are attached to actin filaments
Actin filaments slide back to their relaxed position, which lengthens the sacromere

398
Q

When is aerobic respiration good for for muscle contraction

A

long periods of low intensity exercise

399
Q

what is most ATP generated by

A

Oxidative phosphorylation in the cells mitochondria

400
Q

When is anaerobic respiration for muscle contraction best for

A

short periods of hard exersize

401
Q

how is ATP made by phosphocreatin system

A

ATP is made by phosphorylating ADP- adding a phosphate taken form PCr
PCr is stored inside cells and the ATP-PCr system generates ATP very quickly

402
Q

When is ATP phosphocreatine system used and why

A

During short burst of very vigorous exercise as PCr runs out after a few seconds

403
Q

What 2 words describe ATP-PCr system

A

Anaerobic
Alactic ( doesn’t form any lactate )

A-level Biology (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions