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 http://www.exploratorium.edu/learning_studio/cow_eye/

JointsMuscle 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 BoneBiceps

Triceps Muscles relaxed

Ulna Bone

Ligaments and Tendons

Bone

Muscle

LigamentsTendons 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 placeVitreous humourJelly 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 brainSclerotic 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?

Parts of the eye – what can you remember?

Eye

Objectives:*Describe accommodation

**Distinguish between functions and distribution of rods and cones

AccomodateChanging 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 relaxand suspensory ligaments are pulled tight by the pressure inside the eye.Lens is pulled into elliptical shapeLight rays focus on the retinaLooking at near object:Ciliary muscles contract to counteract inside pressureSuspensory ligament slacksElastic tissue around the lens recoil so lens become spherical (fatter)Light rays are refracted more than before to focus the object on the retinaThe control of the shape of the lens by the ciliary muscle is a simple reflex. Why?

http://www.bbc.co.uk/schools/gcsebitesize/science/ocr_gateway/ourselves/3_keeping_in_touch7.shtml

Retina has two types of cellsRods 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