Antagonistic Muscles & Eye Objectives: *Describe the role of antagonistic muscle as effector **Describe the structure of an eye ***Describe the function of an eye including pupil reflex / /

Joints Muscle s contracted Tendon Radius Bone Cartilage Synovial capsule Synovial fluid The Elbow Joint Stops bones rubbing together and act as a shock absorber Keeps synovial fluid in place Stops bones rubbing together Attaches muscle to bone Humerus Bone Biceps Triceps Muscles relaxed Ulna Bone

Ligaments and Tendons Bone Muscle Ligaments Tendons attach muscle to bone Tendon Ligaments attach bone to bone and hold the joint in place

Muscles & Movement

Exercise : Joints & Muscles Write a paragraph describing how muscles can work in pairs to move bones

Homework : due 19/05 When you pick up a book what kind of response is this? Can you link the movement of muscles and the reflex action in this activity? Write a few sentence about it.

The Eye Hold the lens in place Vitreous humour Jelly like substance which maintains the internal pressure in the eye and its shape Changes thickness of the lens when focussing Choroid Full of black pigment to absorb light and stop reflection Blind Spot optic nerve attaches to the eye here no light sensitive cells Also called yellow spot most sensitive part of retina Inner light sensitive layer with rod and cone cells Controls the intensity of light entering pupil Changes shape to focus light on to the retina Carries nerve impulses away to brain Sclerotic tough, white protective layer Aqueous humour watery liquid fills the front of the eye Light enters eye here Delicate transparent layer for protection Hole through which light enter Tear glands keep the conjunctiva moist, clean eyes by washing and kills bacteria by an enzyme called lysozyme

The light rays are refracted (bent) by the lens and the image is focused on the retina. Light rays reflected off the object enter the eye, through the pupil. How we see

Parts of the eye – what can you remember?

Eye Objectives: *Describe accommodation **Distinguish between functions and distribution of rods and cones

Accomodate Changing focus. Look at something really close up – then far away – it takes time for your eyes to focus. This is called accomodating. Looking at distant object: The ciliary muscles relax and suspensory ligaments are pulled tight by the pressure inside the eye. Lens is pulled into elliptical shape Light rays focus on the retina Looking at near object: Ciliary muscles contract to counteract inside pressure Suspensory ligament slacks Elastic tissue around the lens recoil so lens become spherical (fatter) Light rays are refracted more than before to focus the object on the retina The control of the shape of the lens by the ciliary muscle is a simple reflex. Why?

Retina has two types of cells Rods contain a pigment called rhodopsin that is sensitive to dim light. Thus, this pigment is necessary for night vision (Scotopic vision). They are located at the periphery of the retina. Rods have no ability to detect colours. Cones contain the pigment called iodopsin (Cone pigments) that is sensitive only to bright light. The cones are sensitive to the colours. Not all animals are able to distinguish colours. Human beings, apes, monkeys, birds, lizards, turtles and some fishes are the only animals that are able to distinguish colours well. Most of the domestic animals are colour blind. Most of our cones are in the fovea region. When light stimulates rods and cones they send impulses to the brain via the optic nerve. Brain interprets these images to make a picture. The image is inverted because the way refractiion happen brain interprets it the right way up