1. Your CRAZY Brain
Option a.2
SL/HL Biology

2. Skill: Identifying the parts of the brain in a photograph, diagram, or scan of the brain.

4. The Medulla

5. The role of the Medulla
“Swallowing center”: coordinates the muscles of the mouth, pharynx (throat), and larynx (Adam’s apple)
Allows for food to move down the esophagus to your stomach vs down your trachea (windpipe)
Controls breathing
Monitors levels of CO2 in the blood
If there is an increase in CO2 (aka low O2), the rate and depth of breathing will increase
Cardiovascular center
Causes heart rate to slow down or speed up

6. The Cerebral Cortex Cerebrum develops from front part of neural tube
*Largest part of mature brain*
Two hemispheres (left and right) covered by thin layer of grey matter (cells with no myelin sheath around them) called the CEREBRAL CORTEX
Less than 5mm thick; contains 75% of body’s neurons!!

7. More intelligent animals have more developed cortical surfaces!
The Cerebral Cortex
Responsible for:
Reasoning
Language
Complex thought
Visual processes
Motor movement
Memory
Speech
More intelligent animals have more developed cortical surfaces!

8. The Cerebral Cortex
Greater cognitive ability is correlated with a larger cerebral cortex
Greatest difference between humans and other animals: surface area of cerebral cortex
This is a result of folds (wrinkles!) // larger surface area fits into a limited amount of space

9. Brain vs. Body Size E:S ratio EQ Quotients
Ratio of brain to body weight
E= brain weight, S= body weight
Larger animals = smaller brain to body ratio
(small mice have a large brain vs large elephants have a
relatively small brain)
EQ Quotients
Formula using brain weight (E), body weight (S), a
Constant (C), and an exponential constant (R)
E=Csr
For example: if the EQ of a species is 3.0, then the
Species has a value of C three times as high as a mammal of comparable weight with an average encephalization (ratio of actual brain size vs predicted brain mass)

10. Brain vs. Body Size

14. Key Parts of Cerebral Cortex
Broca’s Area
Speech and language
Speech center**
Nucleus accumbens
Reward center**
Responds to dopamine (promotes desire) and serotonin (inhibits desire)
Drugs can also increase dopamine production, resulting in a trigger of nucleus accumbens and cause addiction
Visual cortex
Receives info from the retina of the eye
Produces vision

15. Left Hemisphere vs Right Hemisphere
Two hemispheres are connected by a thick band of tissue called the CORPUS CALLOSUM
Left Brain
Right Brain
Receives sensory input from right side of body
Receives sensory input from the left side
Controls muscle contraction (voluntary movement) in the left side
Controls muscle contraction (voluntary movement) in the right side
Controls the LEFT SIDE of visual field in both eyes
Controls the RIGHT SIDE of visual field in both eyes

16. Computer Time! Google left brain/right brain activities (online tests)
Complete AT LEAST TWO (2-3)
Record your results (left or right??) on the same paper as your challenge questions
Do you agree or disagree with your results?
We will compare in 15 minutes

17. Brain metabolism and ENERGY
Neurons have high energy need
Brain cells need twice as much energy as any other cells in the body
Glucose is primary energy source
BUT neurons cannot store glucose, so blood must deliver a constant supply
Blood glucose comes from the food you eat
High quality carbs (fruits, veggies, legumes, grains, dairy) are best sources

18. Last thing!
Answer these on the same page as the challenge questions and turn in when completed