Endocrine System Overview

Communication system that uses chemical messengers called hormones, released into the bloodstream and transported to distant target cells.

Chemical messengers produced by endocrine glands that regulate various physiological processes.

Specialized cells or groups of cells that secrete hormones directly into interstitial fluid, from which they diffuse into the bloodstream.

Glands that secrete their products into ducts, which then empty onto a surface or into an organ.

Lipid-soluble hormones, like steroid hormones, that can freely pass through cell membranes and bind to intracellular receptors, often located in the nucleus.

Water-soluble hormones, like peptides and proteins, that cannot easily cross cell membranes but instead bind to receptors on the cell surface.

A type of receptor that spans the cell membrane and is coupled to a G protein, which can activate intracellular signaling pathways.

A molecule that acts as a second messenger inside cells, activated by GPCRs and involved in various cellular processes.

An enzyme that breaks down cyclic adenosine monophosphate (cAMP), a second messenger involved in cellular signaling.

Hormones derived from the amino acid tyrosine, including epinephrine and norepinephrine.

Hormones derived from fatty acids, including prostaglandins, thromboxanes, and leukotrienes.

A small, pea-sized gland located at the base of the brain, connected to the hypothalamus. It is responsible for producing and releasing hormones that regulate other endocrine glands.

The anterior pituitary gland secretes six major hormones, including: Growth hormone (GH), Thyroid-stimulating hormone (TSH), Follicle-stimulating hormone (FSH), Luteinizing hormone (LH), Prolactin, and Adrenocorticotropic hormone (ACTH).

A butterfly-shaped gland located in the neck, responsible for producing thyroid hormones (T3 and T4) and calcitonin.

A hormone produced by the parathyroid glands, responsible for regulating calcium levels in the blood.

A pair of glands located on top of the kidneys, responsible for producing cortisol (stress hormone) and aldosterone (mineralocorticoid).

A small gland located in the brain, responsible for producing melatonin, a hormone that regulates sleep-wake cycles.

A gland located in the chest, responsible for producing hormones that help mature T cells, a type of white blood cell that plays a key role in the immune system.

Hormone secreted by the parafollicular cells of the thyroid gland, which lowers blood calcium levels by inhibiting bone resorption and promoting calcium uptake.

Mineralocorticoid hormone produced by the zona glomerulosa of the adrenal cortex, primarily responsible for regulating sodium and potassium levels in the blood. Aldosterone promotes sodium reabsorption and potassium excretion, leading to increased blood volume and pressure.

Glucocorticoid hormone produced by the zona fasciculata of the adrenal cortex. It plays a crucial role in regulating blood glucose levels by promoting gluconeogenesis and lipolysis, and has potent anti-inflammatory effects.

Hormone secreted by the alpha cells of the pancreatic islets, which raises blood glucose levels by stimulating the breakdown of glycogen (glycogenolysis) and the production of new glucose (gluconeogenesis).

Hormone secreted by beta cells of the pancreatic islets, which lowers blood glucose levels by promoting glucose uptake into cells (glycogenesis), stimulating protein synthesis, and promoting fat storage (lipogenesis).

It is secreted by delta cells of the pancreatic islets, which inhibits the secretion of glucagon and insulin, and also reduces the absorption of nutrients from the gastrointestinal tract.

Hormone released by F cells of the pancreatic islets, which inhibits somatostatin secretion, reduces the secretion of pancreatic digestive enzymes, and weakens gallbladder contraction.

Phase 1 of the ovarian cycle: FSH stimulates follicle development, releasing estrogen.

Phase 2 of the ovarian cycle: Estrogen peaks, triggering LH surge, leading to ovulation.

Phase 3 of the ovarian cycle: Follicle becomes corpus luteum, releasing progesterone.

Phase 1 of the uterine cycle: Shedding of the endometrium due to low progesterone.

Phase 2 of the uterine cycle: Endometrium regrows due to increasing estrogen.

Phase 3 of the uterine cycle: Endometrium secretes nutrients to support a potential embryo.

Fertilization involves the union of haploid sperm and oocyte.

Sperm travel from the vagina, through the cervix and into the uterine tube to fertilize the oocyte.

The sense of smell, involving the detection and interpretation of odor molecules. It begins with olfactory receptor cells in the nasal cavity.

Specialized cells located in the mucous membranes lining the nose. They support and nurture olfactory receptor cells.

The process by which odor molecules are detected and converted into signals that the brain can interpret as smells.

One of four types of papillae on the tongue. They are large, circular structures containing numerous taste buds, responsible for detecting bitter tastes.

Thin, protective mucous membrane that lines the eyelids. It helps keep the surface of the eye moist and clean.

Receptors that respond to painful stimuli, either from physical damage or chemical irritation.

Specialized cells in the retina that detect light.

Receptors that respond to chemical substances in the environment or internal fluids.

Specialized sensory receptors found in the skin that respond to touch, pressure, vibration, and temperature changes.

Proprioceptors located in skeletal muscles that sense muscle stretch and length.

Proprioceptors found at the junction of tendons and muscles that detect changes in muscle tension.

Proprioceptors located around synovial joints that detect changes in joint position, movement, and pressure.

A pathway that transmits sensory information from the periphery (skin, muscles, joints) to the brain.

The nervous system uses neurotransmitters for local communication, while the endocrine system utilizes hormones to send messages throughout the body via the bloodstream.

Lipid-soluble hormones can easily pass through cell membranes and bind to intracellular receptors located in the nucleus.

Water-soluble hormones cannot easily cross cell membranes and instead bind to receptors on the cell surface.

G-protein coupled receptors (GPCRs) activate a cascade of events within the cell, ultimately changing cellular activity.

Cyclic AMP (cAMP) acts as a second messenger, conveying signals from GPCRs to other proteins within the cell.

Endocrine glands release hormones directly into the bloodstream, while exocrine glands secrete their products into ducts that exit the body.

Hormone secretion can be controlled by various factors, including: neural control, hormonal control, and changes in blood composition.

The endocrine system is responsible for long-lasting, widespread effects on various body functions, including metabolism, growth, and reproduction.

An enzyme that breaks down cAMP, a secondary messenger involved in cellular signaling. This process helps regulate the activity of certain hormones and cellular processes.

A category of hormones made from lipids, including prostaglandins, thromboxanes, and leukotrienes. They have various effects, such as inflammation, pain, and blood clotting.

A small gland located at the base of the brain, connected to the hypothalamus. It secretes various hormones that regulate other endocrine glands and bodily functions.

The anterior lobe of the pituitary gland is responsible for producing and releasing seven major hormones, including growth hormone (GH), thyroid-stimulating hormone (TSH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin, adrenocorticotropic hormone (ACTH), and melanocyte-stimulating hormone (MSH).

The posterior lobe of the pituitary gland is made up of neural tissue and predominantly releases two hormones, oxytocin and antidiuretic hormone (ADH).

A butterfly-shaped gland located in the neck, responsible for producing thyroid hormones (T3 and T4) and calcitonin.

Two types of cells are found within the thyroid gland: follicular cells, which produce thyroxine (thyroid hormone), and parafollicular cells, which produce calcitonin, a hormone that regulates calcium levels in the blood.

Four small glands located on the posterior surface of the thyroid gland, responsible for producing and releasing parathyroid hormone (PTH) to regulate blood calcium levels.

A pair of glands located on top of the kidneys, responsible for producing cortisol (stress hormone) and aldosterone (mineralocorticoid) and other hormones.

A small gland located in the brain, responsible for producing melatonin, a hormone that regulates sleep-wake cycles and circadian rhythms.

High blood glucose (hyperglycemia) stimulates beta cells in the pancreas to release insulin.

Insulin's actions include increasing glucose uptake by cells, promoting amino acid uptake and protein synthesis, speeding up glucose conversion to glycogen (storage), and boosting fatty acid synthesis.

Growth factors are signaling molecules that promote cell growth, proliferation, and differentiation.

Gigantism is caused by excess growth hormone secretion, leading to overgrowth of hands, feet, and face.

Goiter is caused by either insufficient or excessive thyroid hormone (TH) production, leading to difficulty breathing and swallowing.

Hypothyroidism is caused by low thyroid hormone (TH) levels, leading to symptoms like depression, weight gain, and cold intolerance.

Graves' disease is caused by excessive thyroid hormone (TH) secretion, resulting in symptoms like irritability, muscle weakness, and heat intolerance.

Cushing's disease is caused by excessive secretion of glucocorticoids, leading to abdominal obesity, weak muscles and bones, and fragile skin.

Paired organs within the scrotum that produce sperm and testosterone.

Tubules within the testes where sperm cells mature and are produced.

This structure stores, matures, and transports sperm from the testes.

A mixture of sperm and fluid from accessory sex glands, contributing to sperm motility and survival.

The external organ in males that serves as the passage for both urine and semen.

Glands that contribute secretions to semen, enhancing sperm function and motility.

A hormone released from the hypothalamus, triggering the pituitary gland to release FSH and LH for male reproductive function.

A hormone produced by the pituitary gland that stimulates the testes' production of testosterone.

A hormone, along with testosterone, supporting sperm production in the seminiferous tubules.

A hormone produced by the testes, crucial for muscle growth, sperm production, and male secondary sex characteristics.

These cells are located in the mucous membranes lining the nose and help support and nourish olfactory receptor cells.

This is the transparent anterior part of the eye, responsible for focusing light onto the retina.

These are photoreceptor cells in the retina that detect bright light and produce color vision.

These cells are located in the retina and detect dim light. They lack color vision and are responsible for night vision.

This is the point in the retina where the optic nerve exits the eye, creating a blind spot. There are no photoreceptor cells in this area.