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UNIT 3 The interaction function Natural Science 2. Secondary Education EXAMPLES OF SENSE ORGANS.

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Presentation on theme: "UNIT 3 The interaction function Natural Science 2. Secondary Education EXAMPLES OF SENSE ORGANS."— Presentation transcript:

1 UNIT 3 The interaction function Natural Science 2. Secondary Education EXAMPLES OF SENSE ORGANS

2 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

3 Sense organs contain receptor cells that capture a particular type of stimulus and send a signal to the nervous system, which interprets it as a sensation. Sense organs Go back to the Start menu 3: The cat’s eyes capture the light reflected from the bird. 2: The cat’s ears capture the vibrations of the bird’s chirp. A cat’s sense organs capturing stimuli. 1: A bird chirps (producing vibrations in air particles) and reflects light. UNIT 3 Examples of sense organs Natural Science 2. Secondary Education

4 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

5 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

6 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

7 Camera-type eyes Lens: This works just like the lens in a camera, focusing objects. Pupil: This serves the same purpose as the diaphragm of a camera. It opens and closes to control the amount of light that enters the eye. Retina: This works like the sensor in a digital camera. It is the innermost layer of the eye. This is where the image received by the eye is formed. This image is formed upside- down, but the brain corrects this and turns it to become an upright image. Iris: A disc made of muscle. Its function is to open and close the pupil. It gives the eye its colour. Optic nerve: This carries the information received by the retina to the brain. Fovea: The part of the retina with the most cones. Sclera: The outermost layer. It is white, except for the front part, the cornea, which is transparent. Choroid membrane: The middle layer of the eye. It is dark red because it is full of blood capillaries. UNIT 3 Examples of sense organs Go back to the Start menu Natural Science 2. Secondary Education

8 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

9 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

10 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

11 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


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