Topic 6A: Stimuli and Responses Flashcards
1
Q
What makes up the CNS?
A
- Brain
- Spinal cord
2
Q
What makes up the PNS?
A
- Somatic - conscious activities
- Autonomic - unconscious activities
3
Q
What are the two parts of the autonomic nervous system?
A
- Sympathetic - increases activity
- Parasympathetic - decreased activity
4
Q
What route does a reflex take?
A
- Stimulus
- Receptor
- Sensory neurone
- Relay neurone
- Motor neurone
- Effector
- Response
5
Q
How are reflexes localised?
A
- Neurotransmitters secreted directly onto cells
6
Q
How are reflexes short lived?
A
- Neurotransmitters are quickly removed
7
Q
How are reflexes rapid?
A
- Electrical impulses are very fast - allows for quick reactions
8
Q
What is a tropism?
A
- Response to a directional stimulus in plants
- Growth response
9
Q
What tropisms do shoots do?
A
- Positively phototropic
- Negatively gravitropic
10
Q
What tropisms do roots do?
A
- Negatively phototropic
- Positively gravitropic
11
Q
What auxin performs tropisms and how is it transported?
A
- Indoleacetic acid (IAA)
- Short distances - diffusion and active transport
- Long distances - phloem
12
Q
What does IAA do in shoots?
A
- Stimulates cell elongation
13
Q
What does IAA do in roots?
A
- Inhibits cell elongation
14
Q
Where does IAA move to?
A
- Lower or shaded side
15
Q
What is a taxis?
A
- Directional movement response to a stimulus
16
Q
What is a kinesis?
A
- Non directional response to a stimulus
17
Q
What performs taxes and kinesis?
A
Invertebrates
18
Q
What are choice chambers?
A
- Have different compartments to create different environmental conditions
19
Q
What are choice chambers used for?
A
- Investigating how animals respond to different conditions
20
Q
What do pacinian corpuscles detect?
A
pressure - in the skin
21
Q
How do pacinian corpuscles work?
A
- Stimulated by pressure
- Lamellae deformed
- Stretches membrane of sensory neurone inside
- Opens stretch mediated sodium ion channels
- Sodium ions move in
- Depolarises
- Generator potential made
- If threshold reached - action potential formed
22
Q
How do photoreceptors work?
A
- Light sensitive pigments absorb light
- Become bleached
- Cause a chemical change - become more permeable to sodium ions
- Generator potential formed
23
Q
What is visual acuity?
A
- Ability to distinguish between two points that are close together
24
Q
What is retinal convergence?
A
- Several rods connect to one bipolar cell
- Summation occurs - effect of neurotransmitters added together so threshold reached more easily
25
What pigment is in rods?
Rhodopsin
26
Where are rods found?
Periphery of retina
27
What do rods make images in?
black and white
28
What sensitivity to light do rods have and why?
- Very sensitive
- Multiple join to one bipolar cell
- Weak generator potentials added together to reach the threshold
29
What visual acuity to rods have and why?
- Low visual acuity
- Multiple join to one bipolar cell
- Cannot tell them apart
30
What pigment is in cones and what colour light are they sensitive to?
- Iodopsin
- Red, green or blue sensitive
31
Where are cones found?
Fovea
32
How sensitive to light are cones and why?
- Less sensitive
- Each join to their own bipolar cell
- Takes more light to reach the threshold
33
What visual acuity do cones have and why?
- High visual acuity
- Close together
- Each join to their own neurone
- Make separate action potentials
34
How is heart rate stimulated?
- SAN sends impulses across the atria causing them to contract
- Non-conducting tissue prevents the atria and ventricles contracting together
- The impulse is delayed at the AVN so that the atria can fully empty of blood before the ventricles contract
- The impulse travels down the bundle of His to the apex of the heart
- Then move up purkyne fibres to make the ventricles contract from the bottom up
35
How is heart rate increased?
- Impulses to medulla
- More frequent impulses down sympathetic nerve releasing neuradrenaline
- The SAN sends impulses more frequently
- Heart rate increases
36
How is heart rate decreased?
- Impulses to medulla
- More frequent impulses sent down the vagus nerve
- Releases acetylcholine
- Decreases frequency of impulses from SAN
- Decreases heart rate
37
What detects CO2 or pH levels in blood?
chemoreceptors
38
What detects blood pressure?
baroreceptors
39
Where are these receptors found?
carotid body
aortic arch
