The brain uses 20% of oxygen and glucose! It needs a constant supply of blood. Without oxygen, brain cells begin to die within 4-6 minutes. The brain is protected by the skull, meninges (three layers of membrane), and cerebrospinal fluid (CSF). The brain is divided into three main parts: cerebrum (largest, responsible for thinking, memory, movement), cerebellum (balance and coordination), and brainstem (automatic functions). So the answer is 20%.

The cerebrum controls voluntary movement and thinking! The left hemisphere controls the right side of the body and is dominant for language and logic. The right hemisphere controls the left side of the body and is dominant for spatial awareness, art, and music. The brain's plasticity (neuroplasticity) allows it to reorganize after injury. So the cerebrum is the answer.

The cerebellum is the answer! It is involved in procedural memory (how to do things). Damage to the cerebellum causes ataxia (loss of coordination, tremors). The cerebellum also contributes to some cognitive functions (attention, language). So the cerebellum helps you ride a bike.

The brainstem controls breathing and heartbeat! The medulla oblongata contains the cardiovascular center and respiratory center. The pons relays signals between the cerebrum and cerebellum. The midbrain controls visual and auditory reflexes. Brain death (no brainstem activity) is legal death in most countries. So the brainstem is the answer.

The brain has about 86 billion neurons! The number of connections (synapses) is about 100 trillion (10^14). Neurons communicate via action potentials (electrical impulses). Myelin sheaths (fatty insulation) speed up signal transmission. Multiple sclerosis (MS) is a disease that damages myelin. Neuroplasticity is the brain's ability to reorganize (form new connections) throughout life. So the number is 86 billion.

The occipital lobe processes vision! The temporal lobe processes hearing (primary auditory cortex) and memory (hippocampus). The frontal lobe is involved in decision-making, planning, and personality (Phineas Gage case). The parietal lobe processes touch (somatosensory cortex) and spatial awareness. So the occipital lobe is the answer.

The hippocampus is the answer! The amygdala processes emotions (fear, anger, pleasure). The hypothalamus regulates body temperature, hunger, thirst, and the pituitary gland (master gland). The limbic system is sometimes called the "emotional brain." So the hippocampus is crucial for memory formation.

The pituitary gland is the master gland! It is located at the base of the brain, below the hypothalamus. Hormones include growth hormone (GH), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), prolactin, oxytocin, and antidiuretic hormone (ADH). The pituitary has two lobes: anterior and posterior. So the answer is the pituitary gland.

A stroke is a "brain attack"! It is a medical emergency. About 87% of strokes are ischemic (blocked artery); 13% are hemorrhagic (bleeding). Time is critical – "time is brain." Stroke is a leading cause of disability and death. Risk factors include high blood pressure, smoking, diabetes, and atrial fibrillation. Treatment includes clot-busting drugs (tPA) within 4.5 hours. So a stroke is interrupted blood flow.

Neuroplasticity is the brain's ability to change! It was once thought that the adult brain could not change, but research has shown that it can. "Use it or lose it" applies to the brain. Learning, experience, and practice strengthen neural pathways. The brain can also reorganize after injury (e.g., stroke recovery). So neuroplasticity is the brain's ability to reorganize.