Brain Anatomy and How the Brain Works
Introduction to the Brain
- The brain is a complex organ responsible for controlling thought, memory, emotion, touch, motor skills, vision, breathing, temperature, hunger, and other bodily processes.
- It forms the central nervous system (CNS) along with the spinal cord.
Composition of the Brain
- Weighs about 3 pounds in adults; consists of 60% fat and 40% water, protein, carbohydrates, and salts.
- Contains blood vessels and nerves, including neurons and glial cells.
- Gray Matter vs. White Matter:
- Gray matter: outer portion of the brain, composed of neuron somas.
- White matter: inner section, made of axons wrapped in myelin.
- Gray matter processes information, and white matter transmits it.
Functionality of the Brain
- Sends and receives chemical/electrical signals throughout the body.
- Signals control different processes; some stay within the brain, others are relayed through the spine.
- Relies on billions of neurons.
Main Parts of the Brain
Cerebrum
- Largest part, includes gray matter (cerebral cortex) and white matter.
- Functions: movement, temperature regulation, speech, judgment, reasoning, emotions, learning, vision, hearing, touch, and other senses.
Cerebral Cortex
- Divided into two hemispheres, covered with gyri and sulci.
- Hemispheres communicate via the corpus callosum.
Brainstem
- Connects cerebrum with spinal cord.
- Composed of:
- Midbrain: involved in hearing, movement, and response to changes.
- Pons: origin for cranial nerves, connects midbrain and medulla.
- Medulla: regulates heart rhythm, breathing, and reflexive activities.
Cerebellum
- Located at the back of the head; coordinates voluntary movements, posture, and balance.
Brain Coverings: Meninges
- Three protective layers: dura mater, arachnoid mater, and pia mater.
Lobes of the Brain
- Frontal Lobe: involved in personality, decision-making, movement.
- Parietal Lobe: identifies objects, interprets pain, touch.
- Occipital Lobe: vision.
- Temporal Lobe: short-term memory, speech, smell recognition.
Deeper Structures Within the Brain
- Pituitary Gland: regulates hormone flow.
- Hypothalamus: regulates temperature, hunger, sleep.
- Amygdala: regulates emotion and memory.
- Hippocampus: supports memory and learning.
- Pineal Gland: secretes melatonin for sleep cycles.
- Ventricles & Cerebrospinal Fluid: cushions brain, removes waste.
Blood Supply to the Brain
- Vertebral Arteries and Carotid Arteries supply blood to the brain.
- Circle of Willis connects major arteries, ensuring blood flow.
Cranial Nerves
- 12 cranial nerves enable functions like smell, sight, taste, hearing, and movement.
- First two originate in the cerebrum, others from the brainstem.
The notes summarize the key elements of brain anatomy, its main regions and functions, and other significant structures and systems related to the brain's operation.