TriiodothyronineTriiodothyronine, also known as T3, is a thyroid hormone. It affects almost every physiological process in the body, including growth and development, metabolism, body temperature, and heart rate. Production of T3 and its prohormonethyroxine (T4) is activated by thyroid-stimulating hormone (TSH), which is released from the anterior pituitary gland.
Thyroid hormonesThyroid hormones are two hormones produced and released by the thyroid gland: triiodothyronine (T3) and thyroxine (T4). They are tyrosine-based hormones that are primarily responsible for regulation of metabolism. T3 and T4 are partially composed of iodine, which is derived from food. A deficiency of iodine leads to decreased production of T3 and T4, enlarges the thyroid tissue, and causes the disease known as simple goitre.
Thyroid follicular cellThyroid follicular cells (also called thyroid epithelial cells or thyrocytes) are the major cell type in the thyroid gland, and are responsible for the production and secretion of the thyroid hormones thyroxine (T4) and triiodothyronine (T3). They form the single layer of cuboidal epithelium that makes up the outer structure of the almost spherical thyroid follicle.
Parafollicular cellParafollicular cells, also called C cells, are neuroendocrine cells in the thyroid. They are called C cells because the primary function of these cells is to secrete calcitonin. They are located adjacent to the thyroid follicles and reside in the connective tissue. These cells are large and have a pale stain compared with the follicular cells. In birds and teleost fishes these cells occupy a structure outside the thyroid gland named the ultimopharyngeal body.
ThyroidThe thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans, it is a butterfly-shaped or H-shaped gland located in the neck below the Adam's apple. It consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the isthmus (pl.: isthmi).
Endocrine glandThe endocrine system is a network of glands and organs located throughout the body. Along with the nervous system, it makes the neuroendocrine system, which controls and regulates many of the body's functions. Endocrine glands are ductless glands of the endocrine system that secrete their products, hormones, directly into the blood.
Connective tissueConnective tissue is biological tissue that is found in between other tissues in the body. Most types of connective tissue consists of three main components: elastic and collagen fibers, ground substance, and cells. It is one of the four primary types of animal tissue along with epithelial tissue, muscle tissue, and nervous tissue. It develops mostly from the mesenchyme, derived from the mesoderm, the middle embryonicgerm layer.
Adam's appleThe Adam's apple is the protrusion in the neck formed by the angle of the thyroid cartilage surrounding the larynx, typically visible in men and less so in women. The prominence of the Adam's apple increases in most men as a secondary sex characteristic during puberty.
Lobe (anatomy)In anatomy, a lobe is a clear anatomical division or extension of an organ (as seen for example in the brain, lung, liver, or kidney) that can be determined without the use of a microscope at the gross anatomy level. This is in contrast to the much smaller lobule, which is a clear division only visible under the microscope. connect lobes and connect lobules.
VertebrateSubphylum of chordatesVertebrates (), also called craniates, are animals with a vertebral column and a cranium. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylumVertebrata ( ) with some 65,000 species, by far the largest ranked grouping in the phylumChordata. The vertebrates include mammals, birds, amphibians, and various classes of fishes and reptiles.
ColloidA colloid is a mixture in which one substance, consisting of microscopically dispersed insoluble particles, is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid, while others extend the definition to include substances like aerosols and gels. A colloid has a dispersed phase (the suspended particles) and a continuous phase (the medium of suspension).*As an Amazon Associate I earn from qualifying purchases.