The Human Brain

1. The Human Brain

2. The Brain • Is protected by the skull and three tough membranes known as meninges • The spaces between the brain and the skull are filled with cerebrospinal fluid, which acts as a shock absorber. • A concussion occurs if the brain is severely shaken and bumps against the skull.

3. The Brain, cont’d • Is a gas guzzler - it comprises 2% of the total body weight, yet uses 25% of the oxygen taken in by the body.

4. Major Parts of the Brain • Cerebrum - largest part of the brain (2/3), which sets humans apart from other animals. • It is divided into left and right hemispheres • The outer layer is called the cerebral cortex and is made of gray matter; the inner layer is white matter • The cerebral cortex carries out sensory functions, as well as memory, learning and thought

5. Two Hemispheres of Cerebrum (top view)

6. Cerebrum

8. Major Parts of the Brain • Cerebellum - found at the back of the brain • It is also divided into left and right hemispheres with gray matter on the outside and white matter inside. • It controls all voluntary movements and plays a major role in balance and coordination

9. Cerebrum Cerebellum

10. Major Parts of the Brain • Medulla Oblongata - found at the base of the brain, below the cerebellum • It is made mainly of nerve fibers that connect the spinal cord to other parts of the brain. • It controls many involuntary actions such as breathing, heartbeat, blood flow, and coughing.

11. Cerebrum Cerebellum Medulla Oblongata

13. Major Parts of the Brain • Corpus Callosum - found in the center of the cerebrum • It is a bundle of nerve fibers in the inner white matter. • It makes a bridge-like connection between the two hemispheres of the cerebrum so that information can pass between the two halves.

14. Cerebrum Corpus Callosum Cerebellum Medulla Oblongata

15. Corpus Callosum (bottom view)

16. Major Parts of the Brain • Pons - found just above the medulla oblongata • It serves as a relay system, connecting the spinal cord, medulla oblongata, cerebellum and cerebrum

17. Cerebrum Corpus Callosum Cerebellum Pons Medulla Oblongata

18. Major Parts of the Brain • Hypothalamus - found in the center of the cerebrum • It controls body temperature, thirst and hunger, sleep, and emotions. • It is associated with maintaining homeostasis. • It also plays a role in the functioning of the endocrine system. • Thalamus – coordinates and interprets sensory information and directs it to the cerebrum

19. Cerebrum Corpus Callosum Cerebellum Pons Thalamus Hypo-thalamus Medulla Oblongata

20. Maintaining Homeostasis

22. Major Parts of the Brain • Pituitary Gland - found below the hypothalamus. • It is referred to as the master gland because it controls all the other endocrine glands.

23. Cerebrum Corpus Callosum Cerebellum Pons Thalamus Pituitary Gland Hypo-thalamus Medulla Oblongata

24. Meet Phineas Gage The year is 1848. Phineas Gage is 25 years old. He is quiet, hard-working and responsible. He has been promoted to foreman and he and his team are blasting through rock to lay a railroad in Vermont. The correct procedure for blasting is to put dynamite down the hole, pour in some sand, and pack it down with a tamping iron. The dynamite would then be lit from a safe distance to blast the rock. Phineas forgot the sand and a spark from the tamping iron caused an accidental explosion. This caused the 3 foot tamping iron to be propelled through the bottom of his left cheekbone and out the top of his head. It flew in an arc across the sky and landed 100 feet behind him.

25. The amazing thing is that after a few moments of being unconscious, Phineas was sitting up and talking to his coworkers!

26. Phineas was alive but he was not the same man. The once mild-mannered, well-liked man had turned into a man with a violent temper, who swore all the time. He lost his job on the RR and had a hard time holding down a job at all. He eventually went travelling with the circus and telling his story. He took the famous tamping iron with him. He died about 12 years later from epileptic convulsions.

27. His body was buried in 1860 but exhumed in 1867. His skull and the tamping iron are now on display at Harvard University’s School of Medicine.

28. The accident destroyed much of Phineas’ left frontal lobe. His was the first case to suggest that parts of the brain might affect personality and behavior.

29. Lobes of the Cerebrum