The Human Brain

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.

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.

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

Two Hemispheres of Cerebrum

(top view)

Cerebrum

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

Cerebrum

Cerebellum

Tumor between meninges and cerebral cortex

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.

Cerebrum

Cerebellum

Medulla Oblongata

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.

Cerebrum

Cerebellum

Medulla Oblongata

Corpus Callosum

Corpus Callosum

(bottom view)

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

Cerebrum

Cerebellum

Medulla Oblongata

Corpus Callosum

Pons

Major Parts of the Brain• Hypothalamus - found in the center of the

cerebrum– It controls body temperature, blood pressure,

sleep, and emotions.– It is associated with maintaining homeostasis.– It also plays a role in the functioning of the

endocrine system.

Cerebrum

Cerebellum

Medulla Oblongata

Corpus Callosum

Pons

Hypo-thalamus

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.

Cerebrum

Cerebellum

Medulla Oblongata

Corpus Callosum

Pons

Hypo-thalamus

Pituitary Gland