Understanding Body Systems: Nervous and Endocrine

Nervous System Actions: Reflexes and Voluntary Acts

Reflex acts are fast and automatic, and do not involve conscious brain processing. These acts occur when a quick response is needed.

Neurons Involved in Reflexes

• Sensory neurons: Come from the skin and their axons enter the spinal posterior roots.
• Interneurons: Synapse with sensory neurons and transmit nerve impulses to other neurons.
• Motor neurons: They leave the spinal cord by the anterior roots and reach muscles, causing contraction and reflex.

Voluntary acts are varied, changing, and more elaborate than reflexes, involving the cerebral cortex.

Autonomic Nervous System

Also called the involuntary nervous system, it is responsible for the proper regulation and coordination of internal organs.

Types of Autonomic Nervous System

• Sympathetic nervous system: Responsible for activating the body's organs to work more intensively.
• Parasympathetic nervous system: Responsible for relaxation and slower, less intense work of the organs.

The Endocrine System

The endocrine system is a coordinator and effector system consisting of endocrine glands that produce hormones. Hormones are organic molecules that travel through the blood to reach certain cells where they carry out actions such as coordination, control, and regulation of various organs. Each hormone acts on a specific cell, called a target cell.

Specific receptors are located in the cytoplasmic membrane or the cytoplasm of target cells.

Diseases Affecting the Nervous System

Degenerative Conditions

• Alzheimer's: Patients begin to lose memory, particularly of recent events.
• Parkinson's: Characterized by the appearance of involuntary trembling movements, most visible in the hands, and decreased muscle strength.

Mental Health Conditions

• Schizophrenia: Lack of coordination between thoughts, feelings, and actions.
• Neuroses: Chronic disorders resulting from intense internal conflict.
• Psychosis: A set of conditions that can have serious social consequences.
• Anorexia: A disorder affecting teenagers and young adults, where patients voluntarily stop eating.
• Depression: Individuals affected by this disorder lose interest in most things, experience anxiety, a sense of failure, and various physical symptoms.

Other Nervous System Diseases

• Infectious Diseases: The most common and significant are meningitis and polio.
• Epilepsy: Seizures are manifested by unconsciousness and can be triggered by visual or auditory stimuli.

Diseases Affecting the Endocrine System

• Diabetes: Due to decreased secretion of insulin by the pancreas.
• Hypothyroidism: Deficient production of thyroxine by the thyroid gland, which reduces the metabolic activity of tissues. Affected individuals may gain weight, have decreased physical activity, and experience pale, cold skin.
• Hyperthyroidism: Due to excess production of thyroxine.
• Endocrine Dwarfism: Growth arrest due to lack of growth hormone secreted by the pituitary gland.