Human Endocrine and Nervous Systems

Endocrine System

The endocrine system is formed by cells and glands that secrete specific hormones. These hormones are effective messengers that regulate various bodily functions through feedback mechanisms.

Endocrine Glands

Pituitary Gland

Anterior Lobe

• GH (Somatotropin)
• ACTH (Adrenocorticotropin)
• TSH (Thyroid Stimulating Hormone)
• PRL (Prolactin)
• FSH (Follicle-Stimulating Hormone)
• LH (Luteinizing Hormone)

Posterior Lobe

• Vasopressin (ADH - Antidiuretic Hormone)
• Oxytocin

Hypothalamus

The hypothalamus controls the neurohypophysis through nerve fibers and releases or inhibits pituitary factors.

Adrenal Glands

Cortex

• Glucocorticoids: Regulate carbohydrate and protein metabolism and inhibit the immune response.
  • Cortisol
  • Corticosterone
• Mineralocorticoids: Regulate Na-K balance.
  • Aldosterone
  • Deoxycorticosterone

Medulla

• Epinephrine (Adrenaline): Sympathetic neurotransmitter of the ANS
• Norepinephrine (Noradrenaline): Sympathetic neurotransmitter of the ANS
• Dopamine

Thyroid

• Calcitonin: Decreases blood calcium levels
• Thyroxine (T4)
• Triiodothyronine (T3)

Parathyroid

Four formations that secrete PTH (Parathyroid Hormone), which regulates calcium and phosphorus levels.

Pancreas

• Insulin: Regulates blood sugar levels
• Glucagon: Increases blood sugar levels
• Somatostatin: Inhibits GH
• Pancreatic Peptide

Pineal Gland (Epiphysis)

Located in the roof of the brain, it secretes melatonin, which is regulated by daily light exposure and inhibits gonadotropin, influencing circadian rhythms.

Ovaries

• Estrogens (Estradiol): Responsible for secondary sex characteristics
• Progesterone: Prepares the uterus for pregnancy

Placenta

• Chorionic Gonadotropin: Stimulates the corpus luteum to produce progesterone
• Relaxin: Relaxes the cervix and pelvis during pregnancy

Testes

Produce androgens, primarily testosterone.

Kidneys

• Renin: Causes vasoconstriction and raises blood pressure
• Angiotensin
• EPO (Erythropoietin): Stimulates erythrocyte formation

Intestinal Tract

• Gastrin: Stimulates HCl production and stomach motility
• Secretin: Stimulates pancreatic secretion in the duodenum

Nervous System (NS)

Central Nervous System (CNS)

Brain

Protected by cerebrospinal fluid (CSF) and meninges (pia mater, dura mater, arachnoid). It is composed of the cerebrum, cerebellum, and brainstem (including the medulla oblongata).

Cerebrum

• Right Hemisphere: Artistic sensibility, communication, affectivity
• Left Hemisphere: Logical-mathematical reasoning, spatial orientation, language
• Cerebral Cortex: Controls feelings, higher brain functions (thought, intelligence, visual interpretation, speech), and some sensory and motor areas.
• Limbic System: Controls basic emotions (hate, sadness, fear, euphoria), olfaction, memory, and behavior.
• Hypothalamus: Controls vegetative functions (hunger, thirst, sexual behavior), dreams.
• Pituitary Gland: Neuroendocrine integration
• Pineal Gland (Epiphysis): Regulates circadian rhythms

Cerebellum

Coordinates motor function.

Brainstem (Medulla Oblongata)

Controls essential life functions like heartbeat, respiration, and digestion.

Spinal Cord

Protected by meninges, it has a butterfly shape with internal gray matter and external white matter. It connects to 31 pairs of nerves and functions as a reflex center. Lymph node chains run parallel to the spinal cord.

Peripheral Nervous System (PNS)

Composed of nerves and ganglia. Nerves can be sensory (afferent) or motor (efferent). The reflex arc is the basic unit of integrated neural activity.

Somatic Nervous System

Controls somatic reflex actions (involuntary, unconscious, and automatic) and voluntary responses.

Autonomic Nervous System (ANS)

Controls visceral, involuntary, and necessary functions. Can be conditioned and is controlled by the spinal cord, medulla oblongata, and hypothalamus.

Sympathetic Nervous System

Prepares the body for action (fight-or-flight response) using adrenaline.

Parasympathetic Nervous System

Prepares the body for rest using acetylcholine.