Human Body Systems: Nervous, Endocrine, and Brain Health

The Central Nervous System

The Central Nervous System (CNS) is the central control and coordination center of the organism. It is able to perceive stimuli and develop responses. It consists of the brain, where responses are made conscious and voluntary, and the spinal cord, where responses are involuntary.

The brain is protected by the skull and covered by three membranes called meninges. Between two of these, cerebrospinal fluid circulates inside the brain. Three regions are distinguished within the brain: the cerebrum, cerebellum, and medulla oblongata.

The Peripheral Nervous System

The Peripheral Nervous System (PNS) consists of nerves, both sensory and motor. According to their origin, nerves are called:

• Cranial Nerves: Those that come from the brain, such as the optic nerve, acoustic nerve, or facial nerve.
• Spinal Nerves: Those that come from the spinal cord, such as the sciatic nerve.

According to their function, the peripheral nervous system is divided into:

• Somatic Nervous System: Innervates skeletal muscles responsible for voluntary movements, such as walking.
• Autonomic Nervous System: Responsible for involuntary activity of internal organs, like the movements of the intestine and heart.

Key Concepts in Neurology

Epilepsy

This occurs when a group of neurons in the central nervous system produces a series of nerve impulses that disrupt normal brain function.

Dementia

Dementia is a progressive loss of intellectual functions a human being possesses.

Neurons: The Building Blocks of the Nervous System

Neurons are highly specialized and numerous cells, crucial for transmitting nerve impulses.

• Dendrites: Short and numerous. They capture nerve impulses that come from a receptor or from another neuron.
• Axon: A single, very long prolongation. The axon, or nerve fiber, can transmit nerve impulses to remote areas of the body.

Synapses

Synapses are the way in which neurons form continuous networks. It is a space between neurons that a nerve impulse must traverse to pass from one to another.

Homeostasis

Homeostasis acts by coordinating the activities of tissues, organs, apparatuses, and systems to maintain internal stability.

The Endocrine System and Hormones

Hormones

Hormones are substances secreted by specialized cells located in ductless glands or endocrine glands.

Hypothalamic-Hormonal Axis

Hypothalamic-hormonal activities control the body and act as a liaison between the nervous and hormonal systems.

Pituitary Gland

The pituitary gland produces hormones that control the activity of some endocrine glands and other hormones like growth hormone or antidiuretic hormone.

Thyroid Gland

The thyroid gland produces the hormone thyroxine, which regulates growth, stimulates cell activity, and is involved in the maturation of the central nervous system.

Pancreas

The pancreas produces insulin and glucagon. These two hormones regulate the level of glucose in the blood.

Impact of Drugs on the Nervous System

Drugs are chemicals of different origins that act on the nervous system. Types of drugs include:

• Stimulants: Cocaine produces euphoria and reduces fatigue. It can cause heart attack and even death.
• Depressants: Heroin causes apathy, fatigue, and loss of self-control.
• Hallucinogens: Marijuana causes confusion, loss of control, and mental imbalance.