Human endocrine glands diagram

\( \newcommand\): Endocrine System Endocrine glands and cells are located throughout the body and play an important role in homeostasis The ductless endocrine glands are not to be confused with the body’s exocrine system, whose glands release their secretions through ducts. Examples of exocrine glands include the sebaceous and sweat glands of the skin. As just noted, the pancreas also has an exocrine function: most of its cells secrete pancreatic juice through the pancreatic and accessory ducts to the lumen of the small intestine Contributed by Open Stax CNS

The endocrine system is a collection of glands that secrete various chemicals called hormones. These are messages that pass signals through the blood to a targeted organ. The receptor cells recognize these messages and act accordingly. Hormones are divided into three classes based on their structure: • Steroids • Peptides • Amines The steroid hormones are derived from cholesterol after a series of biochemical reactions. They pass through the bloodstream, and are not stored by cells. The production of this hormone depends on the rate of synthesis. The peptide hormones are synthesized as precursor molecules. Endoplasmic reticulum and Golgi bodies process these chemicals that are stored in secretory granules, which further help in their secretion into the blood stream, as and when the body demands it. The amine hormones are stored in the cytoplasm as granules till needed. Endocrine System Organs There are over 20 major hormones that are pumped into the bloodstream directly by the endocrine system glands. This system organs consists of the following glands in human begins: • Hypothalamus • Pituitary Gland • Pineal Gland • Thyroid Gland • Parathyroid Glands • Adrenal Glands • Islets of Langerhans (Pancreas) • Ovaries (Females) • Testes (Male) Endocrine System Functions Pituitary gland Antidiuretic hormone (vasopressin) Helps the kidneys to retain water, and controls blood pressure in the presence of aldosterone. Luteinizing and follicle-stimulating hormone Controls reproductive...

endocrine system, any of the systems found in animals for the production of hormones, substances that regulate the functioning of the organism. Such a system may range, at its simplest, from the neurosecretory, involving one or more centres in the Comparative endocrinologists investigate the evolution of endocrine systems and the role of these systems in animals’ An understanding of how the endocrine system is regulated in nonmammals also provides essential information for regulating natural populations or captive animals. Artificial control of salmon reproduction has had important Evolution of endocrine systems The most primitive endocrine systems seem to be those of the The Human Body It has become obvious that many of the hormones previously Vertebrates (phylum Vertebrata) are separable into at least seven discrete classes that represent evolutionary groupings of related animals with common features. The class Agnatha, or the jawless fishes, is the most primitive group. Class Chondrichthyes and class Osteichthyes are jawed fishes that had their origins, millions of years ago, with the Agnatha. The Chondrichthyes are the cartilaginous fishes, such as sharks and rays, while the Osteichthyes are the bony fishes. Familiar bony fishes such as goldfish, trout, and bass are members of the most advanced subgroup of bony fishes, the teleosts, which developed lungs and first invaded land. From the teleosts evolved the class The human endocrine system is the product of millions of...

The glands of the endocrine system secrete hormones into the bloodstream to maintain homeostasis and regulate metabolism. The hypothalamus and the pituitary gland are the command and control centers, directing hormones to other glands and throughout the body. Other primary endocrine glands, including the thyroid and parathyroid glands, the adrenal glands, and the pineal gland, adjust the levels of various substances in the blood and regulate metabolism, growth, the sleep cycle, and other processes. Organs such as the pancreas also secrete hormones as part of the endocrine system. Secondary endocrine organs include the gonads, kidneys, and thymus. 1. Command Centers: The Hypothalamus and the Pituitary Gland Direct the Endocrine System The hypothalamus and the pituitary gland are part of the diencephalon region of the brain. The hypothalamus connects the nervous system to the endocrine system. It receives and processes signals from other brain regions and pathways and translates them into hormones, the chemical messengers of the endocrine system. These hormones flow to the pituitary gland, which is connected to the hypothalamus by the infundibulum. Some hypothalamic hormones are stored in the pituitary stores for later release; others spur it to secrete its own hormones. The hormones released by the pituitary gland and the hypothalamus control the other endocrine glands and regulate all major internal functions. 2. The Pineal Gland Runs a Daily Biological Clock The pineal gl...

Learning Objectives By the end of this section, you will be able to: • Distinguish the types of intercellular communication, their importance, mechanisms, and effects • Identify the major organs and tissues of the endocrine system and their location in the body Communication is a process in which a sender transmits signals to one or more receivers to control and coordinate actions. In the human body, two major organ systems participate in relatively “long distance” communication: the nervous system and the endocrine system. Together, these two systems are primarily responsible for maintaining homeostasis in the body. Neural and Endocrine Signaling The nervous system uses two types of intercellular communication—electrical and chemical signaling—either by the direct action of an electrical potential, or in the latter case, through the action of chemical neurotransmitters such as serotonin or norepinephrine. Neurotransmitters act locally and rapidly. When an electrical signal in the form of an action potential arrives at the synaptic terminal, they diffuse across the synaptic cleft (the gap between a sending neuron and a receiving neuron or muscle cell). Once the neurotransmitters interact (bind) with receptors on the receiving (post-synaptic) cell, the receptor stimulation is transduced into a response such as continued electrical signaling or modification of cellular response. The target cell responds within milliseconds of receiving the chemical “message”; thi...

What Is the Endocrine System? The If your endocrine system isn't healthy, you might have problems developing during What Is a Gland? A gland is an organ that makes and puts out hormones that do a specific job in your body. Endocrine and exocrine glands release the substances they make into your bloodstream. Endocrine System Functions Your endocrine system: • Makes hormones that control your • Controls how your hormones are released • Sends those hormones into your bloodstream so they can travel to other body parts Parts of the Endocrine System Many glands make up the endocrine system. The hypothalamus, pituitary gland, and pineal gland are in • Hypothalamus . This organ connects your endocrine system with your • Pituitary gland. This is your endocrine system’s master gland. It uses information it gets from your brain to tell other glands in your body what to do. It makes many important hormones, including growth • Pineal gland. It makes a chemical called • Thyroid gland . This gland makes thyroid hormone, which controls your growth and • Parathyroid. This is a set of four small glands behind your thyroid. They play a role in • Thymus. This gland makes white blood cells called T-lymphocytes that fight infection and are crucial as a child's • Adrenals. Best known for making the "fight or flight" hormone adrenaline (also called • Pancreas . This organ is part of both your digestive and endocrine systems. It makes digestive enzymes that break down food. It also makes the hormo...