The cerebrum is the largest part of the brain and is responsible for higher-level functions such as consciousness, thought, and voluntary movement.

The spinal cord is a long, thin bundle of nerve tissue that runs from the brain down the back. It is responsible for transmitting signals between the brain and the rest of the body.

Sensory neurons transmit signals from the body to the brain, motor neurons transmit signals from the brain to the body, and interneurons connect sensory neurons to motor neurons.

The myelin sheath is a fatty substance that surrounds the axons of some neurons. It helps to insulate the axons and speed up the transmission of nerve signals.

The blood-brain barrier is a network of blood vessels that prevents harmful substances from entering the brain. It helps to protect the brain from infection and damage.

The sciatic nerve is the largest nerve in the human body. It runs from the lower back down the back of the leg to the foot.

The autonomic nervous system is a part of the nervous system that controls involuntary functions such as breathing, digestion, and heart rate.

Neurons are the cells that transmit signals in the nervous system, while glial cells are cells that support neurons and help them to function properly.

The cerebellum is a part of the brain that is responsible for controlling balance and coordination.

The hypothalamus is a small region of the brain that is responsible for regulating body temperature, controlling hunger and thirst, and producing hormones.

The pituitary gland is a small gland located at the base of the brain. It produces hormones that regulate growth and development, control reproduction, and help the body to respond to stress.

The thyroid gland is a small gland located in the neck. It produces hormones that regulate metabolism, control growth and development, and help the body to use energy.

The adrenal glands are two small glands located on top of the kidneys. They produce hormones that regulate blood pressure, control the immune system, and help the body to respond to stress.

The pancreas is a large gland located behind the stomach. It produces hormones that regulate blood sugar levels, produces digestive enzymes, and helps the body to absorb nutrients from food.

The liver is the largest organ in the body. It filters toxins from the blood, produces bile, stores energy, and helps the body to digest food.