1. UNIT 3 The interaction function Natural Science 2. Secondary Education THE INTERACTION FUNCTION PROCESSES

2. UNIT 3 The interaction function processes 1: Light makes a bird visible to the cat. The bird also emits sound vibrations (chirping). 2: The visual and acoustic signals reach the cat’s sensory organs. 3: The sensory organs send the information they receive to the central nervous system. First, the receptor organs of living things capture information and send signals to the processing centres. Natural Science 2. Secondary Education

3. The central nervous system processes the information received and produces a suitable response (there is a bird there and I’m going to try to catch it). Then, the coordination centres process the signals from the receptors and prepare a response. UNIT 3 The interaction function processes Natural Science 2. Secondary Education

4. The cat’s muscles, part of its locomotor system, receive the order to respond and carry out movements in order to try to catch the prey. Finally, the effectors receive the signals from the coordination centres and carry out the response. UNIT 3 The interaction function processes Natural Science 2. Secondary Education

5. UNIT 3 Examples of sense organs SENSE ORGANS Click on each box to find out more CHEMORECEPTOR ORGANS PHOTORECEPTOR ORGANS MECHANORECEPTOR ORGANS Natural Science 2. Secondary Education

6. The photoreceptor organs of animals are the eyes. They capture light and permit sight. They are normally on the head. Photoreceptor organs UNIT 3 Examples of sense organs Natural Science 2. Secondary Education

7. Depending on their complexity, eyes can be classified into different categories: Simple eyes. Many invertebrates have these. They only detect the presence or absence of light. Compound eyes. Arthropods have these. They are made up of thousands of individual photoreceptor units called ommatidia. Together, these units provide the animals with a mosaic image. Types of eyes (I) The compound eye in an insect. Ommatidium Compound eye Simple eye UNIT 3 Examples of sense organs Natural Science 2. Secondary Education

8. Camera-type eyes. Some invertebrates, such as cephalopods, have these eyes, and almost all vertebrates have them. Their structure is similar to that of a camera and they provide clear images of the animal’s surroundings. Types of eyes (II) The camera-type eye of a bird UNIT 3 Examples of sense organs Natural Science 2. Secondary Education

9. There are various types of mechanoreceptor organs which differ depending on the stimulus they capture: Hearing organs (ears): These are usually holes that capture vibrations in the air or water. Balance organs: Cells that are sensitive to gravity and indicate the position of the animal’s body. Mechanoreceptor organs (I) A reptile’s ear Ear opening Structures that detect vibrations UNIT 3 Examples of sense organs Natural Science 2. Secondary Education

10. Lateral line: Found in fish. This line detects vibrations and movements in the water. Skin: The skin has receptor cells that respond to pressure. It provides the sense of touch. Mechanoreceptor organs (II) The lateral line of a fish Receptor cell Channel Skin UNIT 3 Examples of sense organs Go back to the Start menu Natural Science 2. Secondary Education

11. These capture substances which are in the air, water and foods. They provide two closely related senses: smell and taste. Chemoreceptor organs UNIT 3 Examples of sense organs Natural Science 2. Secondary Education

12. Usually, these receptors are located near the mouth. For example: Arthropods: on the antennae. Vertebrates: in the nostrils or on the tongue. Chemoreceptor organs Antennae: These contain many receptors that respond to substances in the air, working as olfactory organs. Tongue: The tongue captures substances from its surroundings and brings them to an olfactory receptor organ UNIT 3 Examples of sense organs Go back to the Start menu Natural Science 2. Secondary Education

13. ANIMAL RESPONSES 1)Movements 2)Secretions 3) Other responses

14. UNIT 3 The movements of animals WHEN MUSCLES CONTRACT THEY PRODUCE MOVEMENTS: INVOLUNTARY VOLUNTARY (LOCOMOTOR SYSTEM) Click on each box to find out more INVERTEBRATES WITH NO EXOSKELETONS ARTHROPODS ECHINODERMSVERTEBRATES Natural Science 2. Secondary Education

15. These occur in the internal organs. An example is the beating of a heart. Involuntary movements The movement of the heart pumps blood around the organism. Go back to the Start menu UNIT 3 Natural Science 2. Secondary Education The movements of animals

16. These are carried out by the locomotor system. They allow an animal to move from one place to another. Voluntary movements UNIT 3 Go back to the Start menu Natural Science 2. Secondary Education The movements of animals

17. The muscles form part of the walls of the body. By contracting them, the animal’s shape changes and it can move. The locomotor system in invertebrates with no exoskeleton 1: When squid’s muscles relax, water enters its body. 2: When muscles contract, shooting out water, the animal is propelled backwards. UNIT 3 Go back to the Start menu Natural Science 2. Secondary Education The movements of animals

18. The locomotor system in arthropods 2: When these muscles contract, they pull on parts of the exoskeleton (in this case, the wings), enabling the animal to move from one place to another. Their muscles are connected to the internal side of the articulated exoskeleton. UNIT 3 Go back to the Start menu 1: Arthropods’ muscles are connected to the exoskeleton. Natural Science 2. Secondary Education The movements of animals

19. The locomotor system in echinoderms 1: The pressure on the ampullae pushes the tube feet out of the animal’s body. 2: The starfish moves. Tube foot Their muscles are associated with a system of tubes and ampullae (sacs) full of water knows as the ambulacral system. UNIT 3 Go back to the Start menu Natural Science 2. Secondary Education The movements of animals

20. The locomotor system in vertebrates 1: The muscles contract and pull the bones. 2: The limbs move, and so does the animal. Their muscles are anchored to parts of the internal skeleton. UNIT 3 Go back to the Start menu Natural Science 2. Secondary Education The movements of animals

21. Animals carry out other types of responses to stimuli besides movements and secretions. For example: Electricity production Light production production Light production production Colour change Click on the buttons to find out more

22. Many animals can change the colour of their skin. They do it in order to camouflage themselves with their surroundings, to scare off predators or to communicate with other members of their species (during mating, for example). Colour change Back Chameleons change colour to blend in with their surroundings. Chameleon Cephalopods can change colour very quickly. Octopus

23. Bioluminescence is the production of light by a living organism, and is more common among marine animals. One interesting example among terrestrial animals is that of fireflies. Theses beetles produce a greenish light at the end of their abdomen in order to attract mates. Light production Firefly Back

24. Some aquatic organisms, like electric eels, or a type of ray called an electric or torpedo ray, can generate electricity inside their bodies and discharge it in the water to stun their prey or predators. Electricity production Electric ray Back