Responses to Stimuli

?
  • Created by: EmiLy1703
  • Created on: 06-11-17 17:12
What is taxis?
A directional response to a stimulus
1 of 52
What two types of taxis are there? What do they relate to?
Positive taxis - towards the stimulus. Negative taxis - away from the stimulus
2 of 52
What is kinesis?
Affected by strength of stimulus (affects rate of movement and turning) - random and non directional
3 of 52
What is phototropism?
The growth of a plant in response to light
4 of 52
What is gravitropism?
The growth of a place in response to gravity
5 of 52
Where does IAA move to in phototropism?
IAA moves to the more shaded parts of the shoots and roots, so there is uneven growth
6 of 52
Where does IAA move to in gravitropism?
IAA moves to the underside of shoots and roots, so there's uneven growth
7 of 52
What is the CNS made up of?
Brain and spinal cord
8 of 52
What does the peripheral nervous system do?
Connects CNS to the rest of the body
9 of 52
What is the peripheral nervous system split up into?
Somatic and autonomic nervous systems
10 of 52
Is the somatic nervous system conscious or unconscious?
Conscious
11 of 52
Is the autonomic nervous system conscious or unconscious?
Unconscious
12 of 52
What is the autonomic nervous system split up into? What do these parts do?
Sympathetic - speed up heart rate. Parasympathetic - slow down heart rate
13 of 52
What detects pressure?
Pressure receptors in the aorta and the carotid artery
14 of 52
What detects pH changes due to the presence of CO2?
Chemoreceptors in the aorta and the carotid artery
15 of 52
Where are signals sent and what happens because of it?
The signals are sent to the medulla oblongata, which sends nervous impulses to the SAN of the heart down either the sympathetic or parasympathetic nerve
16 of 52
The heart is myogenic. What does this mean?
It can contract and relax without receiving signals from nerves
17 of 52
What is a stimulus?
Any change in the internal or external environment
18 of 52
Name the three main types of neurone
Sensory, relay and motor
19 of 52
What is a reflex?
Where the body response to a stimulus without making a conscious decision to respond
20 of 52
How can reflexes help protect the body?
Because they are rapid and unconscious responses - you don't have tp spend time deciding how to respond
21 of 52
An animal responds to a stimulus in its environment. State the role of receptors and effectors in this response (2 marks)
Receptors detect stimuli. Effects bring about a response to a stimulus to produce an effect
22 of 52
The human blink reflex is an involuntary response, which results in the automatic closing of the eyelids (a blink) when an object touches the surface of the eye. Describe the reflex arc involved in this response (4 marks)
Touch receptors on the surface of the eye are stimulated. An electrical impulse is sent along the sensory neurone to a relay neurone, then passed to a motor neurone, which stimulates effector muscles causing them to contract and the eyelids close
23 of 52
The knee jerk is another reflex response. You can test for it by tapping someone just below their patella (knee cap). Suggest why the absence of this response could indicate some damage to a person's CNS (1 mark)
Damage to the CNS could interrupt the transmission of the reflex, preventing the reflex response from occuring
24 of 52
Polio is a virus that can cause damage to the CNS. In severe cases, the virus can damage motor neurons. Suggest and explain how this might lead to paralysis (3 marks)
Motor neurons carry electrical impulses from the CNS to effectors which then respond. Damage to the motor neurones means that the CNS can't communicate with effectors such as muscles, so muscles don't respond and move/are paralysed
25 of 52
What is positive gravitropism?
Growing towards gravity - roots are positively gravitropic and grow downwards
26 of 52
Describe the difference between taxis and kinesis
Taxis - directional stimuli e.g. light. Kinesis - non directional stimuli e.g. humidity
27 of 52
What is the blind spot?
An area with no rods or cones
28 of 52
Where are rods found?
Mainly found in the peripheral parts of the retina
29 of 52
Where are cones found?
Packed together in the fovea at the back of the eye
30 of 52
What type of information do rods give?
Black and white
31 of 52
What type of information do cones give?
Colour
32 of 52
Why are rods very sensitive to light?
Because many rods join to one neurone
33 of 52
Why are cones less sensitive to light?
Because one cone joins to one neuron
34 of 52
Which gives low visual acuity, rods or cones? Why?
Rods because many rods join the same neurone, which means light from two points close together can't be told apart
35 of 52
Which gives high visual acuity, rods or cones? Why?
Cones because cones are close together and one cone joins one neurone. When light from two points hits two cones, two action potentials (one from each cone) go to the brain - so you can distinguish two points that are close together as two separate
36 of 52
Why are receptors described as specific?
They only detect one particular stimulus, e.g. light, pressure or glucose concentration
37 of 52
What do Pacinian corpuscles do?
Decect mechanical stimuli, e.g. pressure and vibrations. They are found in your skin
38 of 52
What happens when a Pacinian corpuscle is stimulated?
It is deformed and it pressed on the sensory nerve ending
39 of 52
What happens after the Pacinian corpuscle is deformed?
The sensory neurone's cell membrane stretches, deforming the stretch mediated sodium ion channels. The channels open and sodium ions diffuse into the cell, creating a generator potential
40 of 52
Explain how the human eye can provide high visual acuity (3 marks)
In the retina/fovea, cones are close together and each cone joins one bipolar neurone. When light from two points hits two cones, action potentials from each cone go to the brain. This means you can distinguish two points as separate points
41 of 52
Where does the process of a regular heart beat start?
In the sinoatrial node (SAN), which is in the wall of the right atrium
42 of 52
What do the sending out of regular waves of electrical activity cause?
The right and lef atria to contract at the same time
43 of 52
What does the band of non conducting tissue prevent?
The waves of electrical activity from being passed directly from the atria to the ventricles
44 of 52
After the SAN, where are the waves transferred to?
The AVN
45 of 52
What is the AVN responsible for?
Passing the waves of electrical activity on to the bundle of His.
46 of 52
Why is there a slight delay before the AVN reacts?
To make sure the atria have emptied before the ventricles contract
47 of 52
What are the bundle of His?
A group of muscle fibres responsible for conducting the waves of electrical activity between the ventricles to the bottom of the heart
48 of 52
What do the Purkyne tissues do?
Carries the waves of electrical activity into the muscular walls of the right and left ventricles, causing them to contract simultaneously from the bottom up
49 of 52
Why do animals need to alter their heart rate?
To respond to internal stimuli, e.g. to prevent fainting due to low blood pressure or to make sure the heart rate is high enough to supply the body with enough oxygen
50 of 52
Name the effectors that are involved in increasing or decreasing heart rate
Cardiac muscles
51 of 52
The control of heart rate is coordinated by specific parts of the heart. Describe the function of: (a) the sinoatrial node (SAN) (b) the Purkyne tissue (2 marks)
The sinoatrial node acts as a pacemaker/sets the rhythm of the heartbeat. The Purkyne tissue conducts electrical impulses through the ventricle walls
52 of 52

Other cards in this set

Card 2

Front

What two types of taxis are there? What do they relate to?

Back

Positive taxis - towards the stimulus. Negative taxis - away from the stimulus

Card 3

Front

What is kinesis?

Back

Preview of the front of card 3

Card 4

Front

What is phototropism?

Back

Preview of the front of card 4

Card 5

Front

What is gravitropism?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Human, animal and plant behaviour resources »