Survival And Response Flashcards
1
Q
How do organisms increase chance of survival
A
Responding to changes in their response external and internal environment eg. Avoiding too hot places
2
Q
What is a stimulus
A
A change in the internal/external environment
3
Q
What are receptors
A
Detect stimuli
4
Q
Give 2 examples of receptors
A
Cells
Proteins on plasma membrane
5
Q
What are effectors
A
Cells that respond to the stimulus
6
Q
How do receptors communicate with effectors
A
Nervous system
Hormonal system
7
Q
What is a sensory neurone
A
Transmit electrical impulses from receptors to the cns
8
Q
What is a motor neurone
A
Transmit electrical impulses from cns to effectors
9
Q
What is a relay neurone
A
Transmit electrical impulses from sensory neurone to motor neurone
10
Q
What chemicals take info from one neurone to another
A
Neurotransmitters
11
Q
What is the cns
A
Brain
Spinal chord
12
Q
What is the peripheral nervous system
A
Neurones that connect cns to the rest of the body
13
Q
What is the somatic nervous system
A
Control conscious activity
14
Q
What is the autonomic nervous system
A
Controls unconscious activities
15
Q
What is the sympathetic nervous system
A
Fight or flight
Makes body ready for action
16
Q
What is the parasympathetic nervous system
A
Calms body
Rest and digest system
17
Q
What is a reflex
A
Body responds to stimulus without a conscious decision
18
Q
Why do reflex’s help survival
A
Don’t have to spend time devising on response
So very rapid
19
Q
Draw a simple reflex arc
A
Receptor Sensory neurone Relay neurone (in grey matter of spinal chord) Motor neurone Effector
20
Q
When can a reflex be overridden
A
When there is a relay neurone involved
21
Q
Why the nervous system localised
A
Neurotransmitters are secreted directly onto target cells
22
Q
Why is the nervous system short lived
A
Neurotransmitters are quickly removed once they’ve done their job
23
Q
What is the nervous system Rapid
A
Electrical impulses are very fast
24
Q
How do plants increase chance of survival with reference to light
A
Grow towards light
Maximum photosynthesis
25
How do plants increase chance of survival with reference to gravity
Shoots grow down in the right direction
26
Define tropism
Plants response to a directional stimulus
27
What is a positive tropism
Plant grows toward stimulus
28
What is a negative stimulus
Plant grows away from the stimulus
29
What is phototropism
Growth of plant in response to light
+ = towards light
- = away from light
30
What is gravitropism
Growth of plant in response to gravity
+ = grow Down
- = grown up
31
What are growth factors
Hormone like chemicals that speed up or slow down growth
32
Where are growth factors produced
Produced in growing regions of plant (shoots and roots)
33
What does auxin do in shoots
Promotes growth by cell elongation
| Cell walls can stretch more
34
At roots what is the effect or roots
Inhibit growth
35
What type of response does IAA respond to
Tropism
36
How does IAA move in the plant
Diffusion and AT
| Phloem
37
What does an uneven distribution of IAA mean
Uneven growth
38
What does IAA do in response to phototropism
IAA moves to the more shaded parts
Shoots = IAA increase on shaded side. Cells elongate. Shoot bends towards the light
Roots = IAA increases in shaded side. Growth inhibited. Root bends downwards
39
What does IAA do in response to gravitropism
IAA moves to the underside
Shoots = IAA increases on lower side. Cells elongate. Shoot grows up
Roots = IAA increases on lower side. Growth inhibited. Root grows down
40
What is a taxes
Animal response
| Towards or away directional stimulus
41
Example of taxes
Light
42
What is a kinesis
Animal response
| Non directional stimulus
43
Example of kinesis
Humidity
44
How does a photo taxes help woodlice
Move away from light source
| Keeps them concealed under stones in day away from predators and in damper conditions to reduce water loss
45
How does woodlice benefit from a humidity kinesis
High humidity = move slow and change direction less
Low humidity = move faster and change direction more to find a new area
It reduces water loss and keeps them concealed from predators
46
Why are receptors specific
Detect one stimulus
47
What is a resting potential
Difference in charge between outside of cell and inside. Generated by Na/K pumps. Causes a pd.
48
What is a generator potential
```
Stimulus detected
Cell membrane gets excited
More permeable
More ions move in and out of cell
Changes pd
```
49
What happens to the generator potential with a bigger stimuli
```
Excites membrane more
More permeable
More ions can move in
Bigger change in pd
Larger generator potential
```
50
What is an action potential
The generator potential reaches the threshold potential
51
What is the strength action potential measured by and why
Father frequency
| Because all action potentials are the same strength
52
What type of receptor is a pacinian corpuscle
Mechanoreceptors (detect pressure)
53
Where are pacinian corpuscles
Skin
54
What is the stricte of a pacinian corpuscle
Contain sensory nerve ending wrapped in lamellae
55
What causes a response at pacinian corpuscles
Lamellae are deformed
Press onto sensory nerve ending
Sensory nerve ending cell membrane stretches
Deforms stretch mediated sodium ion channels
Channels open and Na can diffuse into the cell
Forms generator potential
If it reaches threshold = action potential
56
What type of receptor is in the eye
Photo receptor
57
How does light enter the eye
Pupil
58
What controls how much light enters the eye
Muscles in the iris
59
How are light rays focused in the eye
By lens onto the retina which contains photoreceptors
60
What is the fovea
Area in retina that contains lots of photoreceptors
61
How are nerve impulses carries from the eye to the brain
The optic nerve
62
What is the blind spot in the eye
Where the optic nerve leaves they eye
| Contains no photoreceptors
63
How do photoreceptors work in the eye
Light enters eye
Light absorbed by light sensitive optical pigments
Pigments are bleached
Causes chemical change
Membrane permeability increases to Na ions
Generator potential created
Reaches threshold potential
Impulse sent along bipolar neurone to optic nerve
64
Where are cone cells
Fovea
65
Where are rod cells
On the peripheral of the retina
66
Why are rod and cone cells different
Contain different optical pigments that are sensitive to different wavelengths of light
Rod = black and white
Cone = colour
67
How do u see different colours
The optical pigments (red, blue, green) in cone cells are stimulated in different amounts
68
Why are rod cells more sensitive than cone cells
Work well in dim light
Many rods join to one neurone (summation and retinal convergence)
Many weak generator potentials combine to reach the threshold potential and trigger an action potential
69
Why are cone cells less sensitive
1 cone cells connects to 1 neurone
| Takes more light to reach the threshold potentiel
70
Why do rod cells have low visual acuity
Many rods join to the same neurone (summation)
| Light from 2 points close together can’t be told apart
71
Why do cone cells have high visual acuity
```
Cone cells are close together
1 cone cell joins to 1 neurone
Get an action potential from each cone cell
Can distinguish between the 2 points
(No summations)
```
72
Why is the heart muscle described as myogenic
Can contract and relax without receiving signals from nerves
73
What is the function of the SAN
Sets the rhythm of the heart by sending regular waves electrical impulses to the atrial walls
74
Where is the SAN
The right atrium
75
How does the heart contract
The SAN sends waves of regular electrical impulses to the atrial walls
Causes the right and left atria to constract at the same time
A band of non conduction collagen tissue prevents electrical impulses being sent directly to the ventricles
The electrical activity is sent to the AVN
AVN sends electrical activity to the bundle of his
There is a delay between AVN receiving the impulses and sending them to the bundle of his to make sure the atria have emptied before the ventricles contract
The bundle of his splits into purkyne tissue carrying electrical activity on the muscular walls of the ventricles so they contract at the same time
76
Why is there a delay between the AVN receiving electrical activity and sending it to the bundle of his
To make sure the atria has fully emptied before the ventricles contract
77
What part of the brain controls the SAN
Medulla oblongata
78
Why do animals need to change their heart rate to reasons to stimuli
Prevent fainting from low blood p
| Make sure body has enough oxygen
79
What are pressure receptors called in the heart
Baroreceptors
80
Where are the baroreceptors
Aorta
| Carotid artery
81
Where are chemo receptors for the hr
Aorta
Carotid artery’s
Medulla
82
What do hr chemoreceptors measure
PH of blood (indicates CO2 and O2 conc)
83
What happens at high blood p
```
Baroreceptors detect high blood p
Impulses sent to medulla on parasympathetic neurones
Secretes acetylcholine
Binds to SAN
Heart rate slows and blood p decreases
```
84
What happens to the heart at low blood p
```
Baroreceptors detect low p
Impulses sent to medulla on sympathetic neurones
Secrete noradrenaline
Binds to SAN receptors
Hr increases and blood p increases
```
85
What happens to the heart at high pH (low CO2)
```
Chemoreceptors detect
Impulses sent to medulla on parasympathetic Neurones
Secrete acetylcholine
Binds to SAN receptors
Herat rate decreases and ph decreases
```
86
What happens the the hr at low pH (high CO2)
```
Chemoreceptors detect
Impulses sent to medulla along sympathetic neurones
Secrete noradrenaline
Binds to SAN receptors
Hr increases and PH increase
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