Chapter #12 - Coordination & Response Flashcards
1
Q
Stimuli
A
Changes in the enviornment that can be detected by organisms.
2
Q
Receptors
A
Cells or groups of cells that can detect stimuli.
3
Q
Effectors
A
Parts of the body that respond to stimulus (e.g. muscles and glands)
4
Q
Coordination
A
The way that receptors detect stimuli and pass informationto effectors.
5
Q
What are the 2 ways that most animals pass on information?
A
Nerves and hormones
6
Q
Nerves
A
The fastest method. Part of the nervous system. They are a group of neurone axons lying together.
7
Q
Hormones
A
Slower, but still important. These chemicals are part of the endorcine system that we will learn about later. They are chemicals that are produced by a gland and carried in the blood, which alter the activities of the organ they are targeting.
8
Q
What are neurones?
A
Specialised cells in the human body which conduct electrical impulses quickly. There are several types.
9
Q
Motor neurone
A
Transmits electrical impulses from the central nervous system to an efector.
10
Q
A
11
Q
What are the features of motor neurons?
A
- Typically long
- Have thin fibres of cytoplasm that streach out from the body.
12
Q
What is the longest fiber in the motor neuron?
A
The axon
13
Q
What is the shortest fiber in the motor neuron?
A
Dendrites
14
Q
How long can axons be?
A
1 meter
15
Q
What is the function of dendrites in motor neurons?
A
Dendrites pick up electrical signals called nerve impulses from other neurones nearby.
16
Q
What is the function of myelin sheath?
A
Insulates the nerve fibres so they can carry signals even faster.
17
Q
What are the 2 nervous systems which all mammls have?
A
- Central nervous system (CNS)
=> The brain and the spinal chord - Peripheral nervous system (PNS)
=> Other nerves in the body
18
Q
What is the main function of (CNS)?
A
To coordinate the electrical impulses travelling through the nervous system
19
Q
What does CNS stant for?
A
Central nervous system
20
Q
What does PNS stand for?
A
Peripheral nervous system
21
Q
What is the PNS made of?
A
It is made of nerves that that spread out from the CNS. Each nerve contains hundreds of neurones. It also includes the receptors in our sense organs.
22
Q
Reflex arcs
A
The pathway along which an electrical impulse is passed (sensory neurone/relay neurone/motor neurone).
23
Q
What are important notes about reflex arcs?
A
- They are involuntary.
- They are as useful as they are fast.
- Your brain is made aware of them, but you only realise what is happening after the impulse has been sent to your muscles.
24
Q
What is the explanation of a reflex arc very simply?
A
- Receptor
- Sensory neuron
- Direction of travel of electrical impulse
- motor neuron
- effector
25
Explain the reflex arc of touching a hot plate.
1. Hand touches hot plate.
2. Sensory receptor in hand detects the hot stimulus.
3. Receptor starts off an electrical impulse.
4. Electrical impulse travels to the spinal chord along the axon from receptor cell.
5. This cell is called a sensory neuron because it is carrying an impulse fromfrom a sensory receptor.
6. In the spinal chord, neuron passes impulse to several other neurons. These are called relay neurons because they pass on the impulses.
7. relay neurons pass the impulse to the brain, as well as the motor neuron that will pass it on as to an effector.
8. Impulse passes down axon of a motor neuron to arrive at effector.
9. Arm muscle contracts.
10. Hand is pulled away.
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What is the description of a sensory neuron?
Long dandrites, short axons
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What is the function of a sensory neuron?
Takes informations from our sences to the CNS.
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What is the description of a motor neuron?
Short dandrites, long axons.
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What is the function of a motor neuron?
Carry impulses away from CNS, towards PNS.
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What is the description of a relay neuron?
Long dendrites, short bodies
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Where are relay neurons present?
Only in eyes, brain and spinal chord.
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Synapse
A junction between 2 neurons in order for a nerve impulse to be passed from one neuron to the next, it needs to cross a synaptic gap (a tiny gap between two neurons at a synapse).
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What is inside the axon?
Inside the axon there are hundreds of tiny ventricles (very small vacuoles).
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What do vesicles in the axon contain?
Vesicles contain neurotransmitters - chemical molecules that diffuse acrossthe synaptic gap to set up ans electrical impulsefor the next neuron.
35
Explain the process of synaptic transmission
1. Electrical impulse travels alon the axon.
2. It causes vesicles to move towards the membrane.
3. They fuse with membrane, releasing neurotransmitters into synapses.
4. Neurotransmitters diffuse across gap.
5. Neurotransmitters attach to receptor proteins on next neuron (complementary shape).
6. This binding triggers impulse to begin in that neuron **this happens only in one direction**.
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Sense organs
A group of receptor cells that can respond to a specific stimulus.
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38
What are the main features of the eye?
* Contains receptor cells in the retina.
* Receptor cells are sensitive to light.
* Eye is filled with fluid to keep shape.
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Iris reflex (pupil reflex)
An automatic response to change in light intensity. The receptors are in the retina, the effector is the muscles in thr iris.
40
What muscles are on the Iris?
The circular muscles and radial muscles are antagonistic - a pair of muscles whose contraction has and opposite effect.
41
What must happen for the brain to see a clear image?
For the brain to see a clear image, there must be a clearimage focused on the retina and so light rays must be bent to get the picture into focus.
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What is the function of the cornea in the eye?
The cornea is a transparent layer at the front of the eye that does most of the refraction,
43
What is the function of the lense in the eye?
The lense changes shape to make fine adjusments.
44
The image on the retina is...
upside down. The brain interprets it so you see it the right way up.
45
How does the eye adjust on light rays from far away objects?
Light rays from far away objects do not diverge much. Light does not need much bending (light rays have smaller angles between them).
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How does the eye adjust on light rays from near objects?
Light rays form near objects diverge a lot. Light needs more bending (angles between light rays is greater).
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Adjusting focus
Light rays need different amount of refraction based on distance.
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Thicker lense =
Refracts light more = Looking at nearby objects
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Thinner lense =
Refracts light less = Looking at objects further away
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What are the lenses held by?
Suspensory ligaments
52
What are ciliary muscles and what is there function?
Ciliary muscles change the tension on the suspensory ligaments.
=> When muscle contracts, the ligaments are loosend = lense is thicker.
=> When the muscle relaxes, the ligaments are pulled tight = lense is pulled in.
53
What features protect the eye?
* The eye is in a socket surrounded by bone to protect it.
* Only the front of the eye is not protected by bone.
* Eyelids, eyebrows and eyelashes help to keep dirt/dust and debris out.
54
Describe the surface of the eye?
The surface of the eye is kept moist by fluid made in tear glands. The fluid contains lysozyme which can kill bacteria. It is washed over your eye when you blink.
55
Describe the 2 features of the retina in the eye?
* It's position is on the back of the eye
* It contains receptor cells
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What happens when light falls on receptor cells in your eyes?
It starts an electrical impulse that travels down the **optic nerve** to the brain.
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What does your brain use to build an image for you to see?
The brain uses electrical impulses which have traveld down the optic neve.
58
Why are some people color blind?
Because the receptors which let them see color are different/not working. It is usually genetic.
59
Where are there no receptor cells?
In the blind spot - where the optic nerve leaves the retina
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What happens if light falls onto the blind spot?
If light falls on it, no impulse is sent to the brain.
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What are the 2 kinds of receptors?
Rods and cones
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What are the features of rods?
* Sensetive to dim light
* Do not respond to color
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What are the features of cones?
* Only function in bright light.
* Can distinguish between color.
* 3 different types of cones, sensetive to red, blue, and green light.
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Fovea
Part of the retina where lots of cones are most tightly packed (where light is focussed when looking directly at something).
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Where are rods found and arranged?
In the retina and are not very tightly packed like cones.
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When do we use cones?
When we look at an object directly we use cones to to produce a sharp image in color.
67
What is the iris and its features? What do these features help the eye with?
The iris is the colored part of the eye in fron of the lense:
* It contains pigments, which absorb the light and stop it passing through.
* This is to stop too much light entering and damaging the retina or to allow more light in to reach the retina.
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What are hormones?
Chemicals that are produced by endocrine glands and carried in the blood (plasma). They alter the activities of specific target organs.
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Where is adrenaline secreted?
It is secreted in the adrenal gland (there is one above each kidney)
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Why is adrenaline secreted?
To prepare the body for vigorous action. It has effects that help you cope with danger (fight or flight).
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How is adrenaline made?
When you are scared/excited etc. The brain sends on an impulse to your adrenal glands. They then secrete adrenaline into the blood.
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What are the effects of adrenaline in the body?
* Heart beats faster, supplying oxygen to your brain and muscles faster:
-Causes muscles to be able to carry out aerobic resperation faster.
-Muscles therefor have more energy for fighting or running away.
* Breathing rate increases that more oxygen enters the blood via the lungs.
* Pupils widen allowing more light into the blood.
* Liver releases glucose into the blood:
-This extra glucose + additional oxygen from lungs = increased metabolic reactions.
74
Do plants respond to stimuli?
Plants respond to the enviornment, just like animals do.
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How do plants respond to stimuli?
Usually by changing their:
* rate of growth
* direction of growth
76
Tropism
A growth responce in plants
77
What is a posotive responce (to tropism)?
Growth towards a stimulus.
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What is a negative responce (to tropism)?
Growth away from a stimulus
79
Phototropism
Growth respnce to light
80
Gravitropism
Growth response to gravity
81
What are two types of stimuli plants respond to?
* phototropism
* gravitropism
82
How do shoots and roots respond to light?
* Shoots => grow towards light
* Roots => usually do not respond to light.
83
How do shoots and roots respond gravitropism?
* shoots => negativley gravitropic
* roots => usually posotively gravitropic
84
Auxin
A plant hormone made in the **tip** of shoots (and roots) that moves towards cells causing them to elengate.
85
Describe what occures when a plant recieves the same amount of light throughout the whole shoot.
All of the shoot recieves the same amount of light and auxin diffuses down all sides of the shoot. so all grow equally longer.
86
Describe what occures when a shoot recieves light from only one side.
The auxin moves across the shoot to the shaded side (side with no light). The cells on the shaded side of the shoot will recieve more auxin and so elongate faster - this causes the shoot to curve as it grows (bends the shoot towards the light).
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