Essential Terms: Nervous and Endocrine System Anatomy

The Nervous System

The Nervous System is formed by nervous tissue. It prepares rapid, short-duration responses to nerve impulses that propagate along nerves.

The Endocrine System

The Endocrine System comprises endocrine glands. It produces slow, long-lasting responses through chemical messengers (hormones) that travel through the bloodstream to target organs or cells.

Receptor

A Receptor is a structure capable of perceiving stimuli and transmitting information to the nervous center.

Nerve Center

A Nerve Center is a body (or part of the nervous system) in charge of receiving information perceived by receptors and transmitting responses.

Effector

An Effector is a body responsible for executing responses. This includes:

• Muscles: producing motor responses involving movement.
• Glands: producing secretory responses, involving the secretion of a given substance.

Neuron

A Neuron is a cell that receives and transmits signals. Transmission occurs by means of nerve impulses.

Sensory Nerves

Sensory Nerves transmit captured information from receptors to the central nervous system (brain and spinal cord).

Motor Nerves

Motor Nerves transmit information from the central nervous system to effectors, causing muscle contraction or gland secretion.

Association Nerves (Interneurons)

Association Nerves (or Interneurons) are located within the central nervous system. They connect sensory neurons with motor neurons.

Glia Cells

Glia Cells are interspersed among neurons, providing protection, insulation, and nourishment. Main glia cells include:

• Astrocytes: which nourish neurons.
• Schwann cells: which wrap around the axon of some neurons, forming an insulating myelin sheath.

Central Nervous System (CNS)

The Central Nervous System (CNS) is the body's control center, in charge of regulating all activities.

Peripheral Nervous System (PNS)

The Peripheral Nervous System (PNS) transmits nerve impulses from receptors to the CNS and from the CNS to effectors.

Brain

The Brain is located in the cranial cavity and consists of the following main elements:

Cerebrum

Divided by a groove into two zones: left and right hemispheres. It processes information received from receptors, analyzes it, and issues commands. Responsible for thoughts, memory, language, and other vital functions.

Cerebellum

Located below the cerebrum, divided into two hemispheres. Its function is to coordinate voluntary movements.

Brainstem (Medulla Oblongata)

Located at the base of the brain, connecting to the spinal cord. It controls involuntary functions.

Spinal Cord

The Spinal Cord is a primary structure, approximately the thickness of a little finger. It extends along the body from the base of the skull to the end of the spine.

Somatic Nervous System

The Somatic Nervous System is involved in voluntary body movement.

Autonomic Nervous System

The Autonomic Nervous System acts on basic bodily functions carried out unintentionally, over which the brain has no conscious control. It includes:

Sympathetic Subsystem

Prepares the body for 'fight or flight' situations (activity).

Parasympathetic Subsystem

Prepares the body for 'rest and digest' situations (rest).