Internal and External Stimuli Flashcards
1
Q
What is the order for stimuli response?
A
Stimuli Receptor CNS Effector Response
2
Q
What is the CNS made up of?
A
Brain
Spinal cord
3
Q
What re the two effectors?
A
Muscle= nervous Gland = hormonal
4
Q
What is a stimulus?
A
Detectable change in the eternal or external environment
5
Q
What is a receptor?
A
Any structure able to respond to a change
6
Q
What is a coordinator?
A
The “switchboard” connecting information from the receptor to appropriate effector
7
Q
What is an effector?
A
Causes a response (muscle or gland)
8
Q
What is a response?
A
The output/change in behaviour
9
Q
What are the three type of responses?
A
Tactic (taxis)
Kinetic (kinesis)
Trophic (tropism)
10
Q
How do organisms react to an stimulus in their environment differently?
A
Whole organism or only part of it moves in response
Movement could be directional (+/-) or non-directional
11
Q
Describe a kinetic response
A
Whole organism
Alteration in rate of movement
In response to change in intensity of stimulus
Non-directional
12
Q
What is an example of a kinetic response?
A
When in dry conditions woodlice move rapidly and change direction
In drier areas = slow
13
Q
Describe a taxis response
A
Whole organism
Directed by stimuli
Positive taxis = towards (+)
Negative taxis = away (-)
14
Q
What is an example of a taxis response?
A
Some species of bacteria move away from waste products they produce
(Negative taxis)
15
Q
Describe a trophic movement
A
Movement of part of the organism
Directed by stimulus
Growth response
16
Q
What is an example of a trophic response?
A
Plant roots grow away from light and towards gravity
17
Q
What are the three type of tropisms?
A
Hydrotropism
Geotropism
Phototropism
18
Q
Where are auxins produced?
A
Apical meristem
19
Q
What do auxins do?
A
Cause cells to grow
20
Q
What is IAA?
A
Example of auxin
21
Q
What do auxins do in response to tropism?
A
They move to shaded side = causes uneven growth = cell elongation towards sun
22
Q
Where is IAA made?
A
By cells located throughout plant (not organs)
23
Q
What is IAA produced in?
A
Small quantities
24
Q
What does IAA affect inside of the plant?
A
Tissues close by + tissues the are released from
25
What does IAA affect overall?
Growth
26
What is the CNS?
Central nervous system
27
What is the PNS?
Peripheral nervous system
28
What is the peripheral nervous system
Pairs of nerves from the CNS travelling to limbs + organs (sensory neurone)
29
What are the two main divisions of the PNS?
Somatic - conscious = involves brain
| Autonomic - subconscious = reflex actions
30
What is a reflex?
Involuntary response to a stimuli
31
What are the importance of reflexes?
```
Fast
Automatic
Protective
Innate (not learnt)
Doesn't involve the brain
```
32
Why is it important that reflexes are fast, etc?
Brain can focus on other complex behaviours
| Escape predators, gain food or mates
33
Describe the process of a reflex arc
Sensory neurone takes electrical message from receptor to immediate neurone
Intermediate neurone relays message to motor from sensory
Motor receives from intermediate and sends to effector (muscle)
Muscle will contract so that hands pulls away from stimuli
34
What do receptors do?
Receive info + pass to CNS
35
Are receptors specific?
YES
36
What is sensory perception?
Making sense of information
37
What must happen to sensory information?
Must be converted into info the body understands
38
What converts sensory information?
Transducers
39
Why is the Pacinian Corpuscle important?
It is specific
Involved in sensory reception
Involves in sensory perception
40
What does the Pacinian Corpuscle respond to?
Mechanical pressure
41
Where is the Pacinian Corpuscle found?
Deep skin
| eg. Fingers, toes, external genitalia + ligaments/tendons
42
What does the Pacinian Corpuscle act as?
Transducer
43
What is structure of the Pacinian Corpuscle?
```
Layers of connective tissue
Viscous gel
Blood capillaries (transports O2 + glucose for respiration = release energy)
Neurone endings
Sensory neurone (send message to CNS)
```
44
What happen when pressure is applied to the Pacinian Corpuscle?
Lamellae deforms
Applies pressure to neurone endings
Na channels stretch (stretch mediated Na channels) so Na+ can pass through
Increases permeability of membrane
Na+ move from high to low conc
Via facilitated diffusion
Influx of Na+ changes potential
Once at rest channels change back to normal size
Generator potential results in nervous response
45
What are the two light receptors in the eye?
Rod cells
| Cone cells
46
What do both receptors in the eye act as?
Transducers
47
What do both receptors in the eye do?
Convert light energy into electrical energy of a nerve impulse
48
How do the receptors in the eye work?
Contain a specific pigment
Pigment broken down by specific wavelength of light
High/low light intensity
IF broken down message will be sent
49
Where are rod cells most numerous?
Side of the eye
50
Where are cone cells must numerous?
Fovea
51
What pigment is present in rod cells?
Rhodopsin
52
What pigment is present in cone cells?
3 different idopsin = green, red + blue light
53
What colour image does rod cells produce?
Black and white
54
What colour image does cone cells produce?
Coloured
55
What light intensity is rod cells' pigment broken down in?
Low
56
What light intensity is cone cells' pigment broken down in?
High
57
What is the visual acuity of rod cells?
Low
58
What is the visual acuity of cone cells?
High
59
How many neural connections do rod cells have?
Multiple
60
How many neural connections do cone cells have?
One = own bipolar cell
61
Pigment inside rod cells should be broken down but what else?
Threshold value must be exceeded
| Ensures generator potential reached
62
What are disadvantages of rod cells?
Only generates one impulse regardless of multiple
Cannot distinguish between different sources of light
Low visual acuity
63
What are the two nodes that control the heart?
Sinoatrial (SAN)
| Atrioventricular (AV)
64
What do the two nodes together do?
Iniate the cardiac cycle
65
Describe what happens in the cardiac cycle
Electrical impulse spreads across atria from SAN = atria contracts
Atrioventricular septum (non-conductive tissue) stops impulse from travelling to the ventricles
Electrical activity travels to AVN
After a pause the AVN sends an impulse down the bundle of His
The bundle of His conducts the impulse through AV septum to bottom of ventricle
Punkinje fibres (smaller fibres) continue throughout ventricle wall
Ventricle contracts from base up
66
What node is considered the natural pacemaker and why?
SAN because it iniated contraction of atria
67
What is importance of the Punkinje fibres>?
Smaller branching network which sends nerve impulses to cells in the ventricles of heart
68
Where is the electrical impulse sent once it reaches the AV node?
Bundle of His
69
Where does the ventricle contract from and why is this important?
Apex (base) = more muscle in the ventricle walls to increase the pressure + push blood further
70
Why is there a short delay before the electrical wave leaves the AVN?
Makes sure the atria has emptied before the ventricles contract
71
What is the autonomic system?
All internal systems in the body needed to be controlled + regulated
72
What is the peripheral nervous system?
Pairs of nerves from the CNS travelling to limbs + organs
73
Is autonomic voluntary or involuntary?
Involuntary
74
Is somatic voluntary or involuntary?
Voluntary
75
What is the sympathetic N.S primary process?
To stimulate body's fight mode
76
When does the sympathetic N.S stimulate effectors?
During strenuous activities
| Powerful emotions
77
When does the sympathetic N.S increase in activity?
Times of stress, illness or injury
78
Why is the sympathetic N.S constantly active at basic levels?
To maintain homeostasis
79
Because the sympathetic N.S stimulates what does it do?
Speeds up activities
80
What does sympathetic N.S do for the body?
Heighten awareness'
Prepare for action
Help cope with stressful situations
81
Because the parasympathetic inhibits effectors what does it do?
Slows activity
82
When does the parasympathetic N.S control activities?
Under normal resting conditions
83
What does the parasympathetic N.S deal with?
Conserving energy + replenishing the body's resting reserves
84
When is the parasympathetic N.S active?
State of relaxation
| = Sleep/recovery from illness or injury
85
What is the parasympathetic N.S primary process?
To enable the body to "Rest and Digest"
86
What is the medulla?
A cone-shaped neurone mass
87
What is the medulla responsible for?
Involuntary functions
88
What does the medulla control?
Breathing
Heart rate
Blood pressure
89
What centres does the medulla contain?
Cardiac
Respiratory
Vomiting
90
What are the two type of receptors when controlling heart rate?
Chemoreceptors
| Pressure receptors
91
What does chemoreceptors detect?
pH changes in the blood
92
Where are the chemoreceptors found?
Carotid arteries
93
What does pressure receptors detect?
Pressure changes in the blood
94
Where are pressure receptors found?
Carotid arteries
| Aorta
95
The centre, in the brain, that increases HR is linked to what?
SAN by sympathetic N.S
96
The centre, in the brain, that decreases HR is linked to what?
SAN by parasympathetic N.S
97
What happens when blood pressure is high?
| Pressure receptors
Nervous impulse sent to centre of medulla (decreases HR)
Centre sends impulse via parasympathetic N.S to SAN
Decreases HR
98
What happens when blood pressure is low?
| Pressure receptors
Nervous impulse sent to centre of medulla (increases HR)
Centre receives impulse via sympathetic N.S to SAN
Increases HR
99
How do chemoreceptors work?
```
Increased metabolic activity
More CO2 = pH decreases
Chemoreceptors increase impulses to centre of medulla that increase HR
Via sympathetic NS to SAN
HR increases = blood flow increases
More CO2 removed
pH rises to normal
```
100
What is a feedback loop?
The automatic control system resulting in a return to normal conditions
101
`What is the feedback loop of chemoreceptors?
```
Change in blood pH = stimuli
(Chemo)receptors in carotid arteries
Coordinate centre co-ordinates a response (medulla)
Effector brings about response (heart)
Response returns HR back to normal
```
102
What effect does IAA have on growth of roots?
Inhibits growth
103
Why does vision using the fovea has a high visual acuity
Lots of cones cells present
| Each cone cell has its own neurone
104
How does a high conc of IAA at the bottom of the root cause it to bend?
High conc at bottom so cell only grow at the top, causing it to bend downwards
105
What is the term used to describe the sharing of one neurone by multiple rod cells?
Retinol convergence
106
By which process do plant hormones move from growing regions of a plant to other tissues?
Diffusion
107
How is action potential generated in the Pacinian Corpuscle?
Applies pressure which deforms tissues
This widens stretch mediated Na channels
Causes influx of Na+ into membrane
Changes the potential
108
What is the role of the bundle of His
To conduct electrical message from the AV node to the apex of the heart down the non-conductive septum
109
What is the role of the medulla oblongta
Involuntary responses
