1. RECEPTORS

4. video

7. Camera-type eyes
Choroid membrane: The middle layer of the eye. It is dark red because it is full of blood capillaries.
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.
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.
Fovea: The part of the retina with the most cones.
Iris: A disc made of muscle. Its function is to open and close the pupil. It gives the eye its colour.
Sclera: The outermost layer. It is white, except for the front part, the cornea, which is transparent.
Optic nerve: This carries the information received by the retina to the brain.

8. HEARING

9. Encapsulated nerve endings
THE SKIN: THE TOUCH
Touch allows us to feel many different sensations:
The shape and texture
Pressure
Heat and cold
Pain
Free nerves endings
Encapsulated nerve endings

10. THE SKIN: THE TOUCH
Melanocytes

11. THE SMELL
Gas molecules
video

13. THE TASTE
animation

14. EFFECTORS

15. BONES FUNCTIONS OF BONES: THEY ANCHOR THE MUSCLES
THEY SUPPORT THE BODY
THEY PROTECT DELICATE ORGANS
THEY A RE A CALCIUM RESERVE
BLOOD CELLS ARE PRODUCED IN THE INTERIOR OF BONES.

16. BONES
video

18. JOINTS

20. MUSCLES

21. AGONIST MUSCLES: THEY COOPERATE TO PRODUCE ONE UNIQUE MOVEMENT.
ANTAGONISTS MUSCLES: THEY PERFORM MOVEMENTS IN OPPOSITE DIRECTIONS