Show students a photo of a human brain in the skull, with the .
Discuss how the brain is protected by the skull and how it fills the skull.
Parts of it are for receiving messages from our environment - seeing and tasting and touching. A lot of it is for reasoning and critical thinking. The cortex does all of this. We humans are really good at figuring stuff out - large brain. Also the cerebellum (fine motor control) and hind brain (basic functions like breathing, waking and sleeping).
Show real lamb brain, and image of it in the skull.
Ask students to guess what animal it is. Tell them it came from the butchers.
Lamb brain is small compared to ours, but the parts are the same: cortex, cerebellum, mid brain/hind brain..
We’ll do some activities that use different parts of your brain to show what they do.
It looks like one big mush, but there are distinct parts that do distinct things.
Cortex
The wrinkly part is the cortex. Wrinkles mean you can pack more surface area into the same space.
It has very distinct parts - show image of cortex regions. Frontal lobe is for thinking, emotion, reasoning, memory. Other parts for moving and sensing our environment - seeing, hearing, tasting, touching.
Compare the size of our cortex to other animals (look at diagrams of brains from different animals). Every animal has hind brain parts. Only mammals have a large cortex. Ours is especially large relative to the rest of our brain - we do a lot of reasoning. However our optic and olfactory areas are relatively small.
We’ll experiment with the neurons coming into the touch part of the cortex.
Touch test activity.
Now we will show a circuit of neurons at work, with another part of the brain the thalamus, involved:
Reaction time activity.
Eyes to visual cortex to thalamus to motor cortex through spinal cord to hand.
(The thalamus also regulates conciousness, sleep and alertness.)
(The Corpus callosum, arching above the thalamus, joins the halves of the brain.)
Cerebellum and fine motor control
Show cerebellum in lamb brain. Controls movement.
With straight arms, slowly move your arms up and make your finger tips meet over your head.
You can make them touch without seeing them. Your cerebellum does this.
Now try it in front of you, so you can see your fingers meeting - it is a lot easier because you are now getting input from the sensory part of your cortex, with messages from your eyes.
With a damaged cerebellum a person cannot accurately make their fingers meet - their arms will move around a lot more as they try and reach their target.
Hindbrain and breathing
Look at medulla oblongata (hindbrain) on lamb brain.
We will use our medulla oblongata/hindbrain: ask the students to follow what you do - jumping, running on the spot, jumping jacks etc for at least 2 mins. Then ask them to sit down and think about what their body is doing. Their heart is beating fast and they are breathing harder. They did not have to think about doing those things - their body just did it. The medulla oblongata reads the levels of CO2 in the blood, by measuring the pH of the blood.
Do the CO2 making water more acidic activity to show how CO2 changes the pH. When the pH of the blood falls, as it does when we excercise and increase the amount of CO2 in the blood, the medulla oblongata signals to speed up breathing and heart rate which will increase O2 levels in the blood again.
White and grey matter
Looked at parts of the brain. Can see the parts of the neurons too, by colour.
Show an image of a neuron, with cell body and axon.
Cut sheep brain to see white and pink parts.
White is (myelin of) axons, grey is cell bodies..
Electrical signals jump along the axons - very fast.
Cell bodies make chemicals and axons send the messages.
Touch brain, either the lamb brain or pig brains
Feel the brain and discuss texture compared to meat - squishy, tacky etc.
The students' own brains feel like this!
