How does alcohol damage your liver?
- alcohol is poisonous
- it is broken down by enzymes in the liver and some of the products are toxic.
- if you drink too much alcohol over a long period of time these toxic products can cause the death of liver cells, forming scar tissue that stops blood from reaching the liver.
- this means the liver can’t do its job of cleaning the blood
- therefore dangerous substances will build up and damage the rest of the body.
What does being drunk cause?
- dehydration (which can damage other body cells including the brain)
- impaired judgement
- poor balance
- poor coordination
- slurred speech
- blurred vision
- sleepiness
What does smoking cause?
- heart disease due to carbon monoxide
- lung, throat, mouth and oesophageal cancer as tar from the smoke collects in the lungs. It’s full of toxic chemicals, some of which are carcinogens
- smoker’s cough and a severe loss lung function.
- low birth weight babies as the low oxygen in the blood of a pregnant woman can deprive the foetus of oxygen, leading to a small baby at birth,
What are the parts of the eye?
-cornea
-iris
-retina
-pupil
ciliary muscles
-suspensory ligaments
-optic nerve
What does the iris do?
-controls how much light enters the pupil
What does the lens do?
-refracts light, focuses it onto the retina
What does the cornea do?
-refracts light into the eye
What does the retina do?
-light sensitive part at the ‘back’ of the eye that is covered in rods and cones, which detect light
What do cones do?
-sensitive to colours but not to good in dim light.
What do rods do?
-sensitive in dim light but can’t see colours
What does the optic nerve do?
-carries impulses from the receptors to the brain
What happens when we look at near objects?
- the ciliary muscle contracts, which slackens the suspensory ligaments.
- the lens becomes more rounded, so light is refracted more.
What happens when we look at distant object?
- the ciliary muscle relaxes, which allows the suspensory ligaments to pull tight.
- this pulls the lens into a less rounded shape, so light is refracted less.
What is long-sighted vision and how is is corrected?
- unable to focus on near objects
- the lens is the wrong shape and doesn’t bend the light enough or the eyeball is too short
- the images of near objects are brought into focus behind the retina.
- convex lens
What is near-sighted vision and how is it corrected?
- unable to focus of distant objects
- the lens is the wrong shape and bends the light too much or the eyeball is too long.
- the images of distant objects are brought into focus in front of the retina.
- concave lens or corneal laser surgery
What is binocular vision and how does it work?
- two eyes which work together
- when we look at an object, our brain compares the images seen by each eye.
- the more similarities between the images, the further away the object.
- allowing us to judge distances well, but gives us a narrow field of vision
What are carcinogens?
- chemicals that cause cancer
- they make mutations in the DNA more likely.
- if this happens, cell division can go out of control and malignant tumours can form.
How is smoker’s cough caused?
- smoking damages the cilia on the epithelial tissue lining the trachea, bronchi and bronchioles
- this encourages mucus to be produced
- but excess mucus can’t be cleared because the cilia are damages
- so it sticks to the air passages causing smokers cough.
