Name: how t3 and t4 are made and controlled
Uploaded: 2024-02-01T15:35:00.000Z
Duration: 1 min 20 s
Channel: JoVE

K12 Standards

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

9-12

Human Anatomy and Physiology

Integration And Coordination

Endocrine System

synthesis-and-regulation-of-thyroid-hormones

Synthesis and Regulation of Thyroid Hormones

甲状腺激素（三碘甲腺原氨酸或T3，以及甲状腺素或T4）的血液水平降低时，会向下丘脑发出信号，促使其释放促甲状腺激素释放激素（TRH）。
随后，促甲状腺激素释放激素（TRH）到达垂体，刺激垂体将促甲状腺激素（TSH）释放入血液中。
当到达甲状腺后，TSH 会刺激滤泡细胞主动从血液中摄取碘离子。
离子扩散至细胞的顶膜表面，并被氧化为碘。随后，碘被添加至滤泡胶质中储存的甲状腺球蛋白蛋白上的酪氨酸残基，形成单碘酪氨酸（T1）或双碘酪氨酸（T2）。
一个T1,分子与T2结合形成T3分子，而两个T2分子结合则形成T4。
最后，通过内吞作用和酶解切割，滤泡细胞释放出T3和T4。这些激素随后进入血管，被运输至靶组织。
血液中T3和T4水平的升高会暂时抑制TRH和TSH的生成，从而调节体内甲状腺激素的水平。

甲状腺激素的合成与调节

血液中如甲状腺激素水平过低——三碘甲状腺原氨酸（T3）和甲状腺素（T4）——会向下丘脑发出信号，释放促甲状腺素释放激素（TRH）。 TRH 然后到达垂体并刺激促甲状腺激素 (TSH) 释放到血液中。

到达甲状腺后，TSH 会刺激滤泡细胞从血液中主动摄取碘离子。 离子扩散到细胞的顶面并被氧化成碘。 然后将碘添加到储存在管腔胶体中的甲状腺球蛋白的酪氨酸残基中，形成单碘酪氨酸（T1）和二碘酪氨酸（T2）。 T1 分子与 T2 分子结合形成 T3 分子，而两个 T2 分子结合在一起形成 T4 分子。

最后，胞吞作用和酶裂解释放滤泡细胞中的 T3 和 T4。 然后这些激素进入血管并运输到目标组织。 血液中 T3 和 T4 水平的升高会暂时抑制 TRH 和 TSH 的产生，从而调节体内甲状腺激素的水平。

低水平的甲状腺激素——三碘甲状腺原氨酸（T3）和甲状腺素（T4）——会向下丘脑发出信号，促使其释放……

Education

教育

JoVE Core

Anatomy and Physiology

解剖学与生理学

Unit 1

第 1 单元

The Endocrine System

内分泌系统

KEY TERMS AND CONCEPTS

关键术语与概念

how t3 and t4 are made and controlled

Thyroid hormones T3 and T4 are made through a step-by-step process in the thyroid gland. Their release is also controlled by a feedback loop that helps keep hormone levels balanced in the body.

When blood levels of T3 and T4 drop, the hypothalamus responds by releasing thyrotropin-releasing hormone, or TRH. TRH travels to the pituitary gland and stimulates it to release thyroid-stimulating hormone, or TSH, into the bloodstream.

TSH then acts on the thyroid gland. It stimulates the follicular cells to actively take up iodide ions from the blood. The ions move to the apical surface of the cells, where they are oxidized to iodine.

The iodine is added to tyrosine residues on thyroglobulin, a protein stored in the colloid of the follicle lumen. This forms monoiodotyrosine, or T1, and diiodotyrosine, or T2. One T1 joined with one T2 forms T3, while two T2 molecules combine to make T4.

After that, endocytosis and enzymatic cleavage release T3 and T4 inside the follicular cells. The hormones then enter the blood vessels and travel to target tissues. When blood levels of T3 and T4 rise, they temporarily inhibit TRH and TSH production, which helps regulate thyroid hormone levels.

How T3 and T4 Are Made and Controlled

an overview of the endocrine system

How Hormones Coordinate Body Functions

The endocrine system uses hormones to coordinate body functions. It is a network of glands that releases chemical messengers into the body. These hormones carry signals between secretory cells and distant target cells. A hormone only affects cells that have the right receptor for it. The endocrine system helps maintain homeostasis, or a stable internal balance. It works with the nervous system to regulate metabolism, reproduction, and development. Both systems support intercellular...

structures of the endocrine system

Endocrine Glands and Hormone Sources

The endocrine system is made of glands, tissues, and organs spread across the body. These parts work together to release hormones, which are chemical signals that help control body functions. Endocrine glands are ductless glands, so they release hormones directly into the interstitial fluid, the fluid around cells. The hypothalamus is a key neuroendocrine organ in the brain. It links the nervous system and endocrine system and helps regulate hormones. Near it are the pituitary gland and pineal...

chemical signaling in the endocrine system

chemical-signaling-in-the-endocrine-system

Hormone Receptors and Cell Responses

Hormones control cell activity by binding to receptors and starting a signaling cascade. A signaling cascade is a chain of events that carries information within or between cells and ends with a specific response in the target cell. In the endocrine system, hormone action depends on whether the hormone is lipid-soluble or water-soluble. Lipid-soluble hormones, such as steroid hormones, act inside the cell. Because they are lipid-based, they can pass through cell membranes. They then bind to...

types of hormones

Hormone Structure and Function

Hormones can be grouped by their structure and how they act in the body. The main groups are steroids, eicosanoids, amino acid-based derivatives, and peptide hormones. These categories help explain why some hormones travel easily through cell membranes while others act in more local ways. Steroids and eicosanoids are lipid-soluble hormones, which means they dissolve in fats. Steroids come from cholesterol and have four linked carbon rings with different side chains. Examples include estradiol...

secondary messengers in hormone action

Hormone Signaling Through cAMP and Calcium

Water-soluble hormones signal through cell receptors and second messengers. Because these hormones cannot cross the plasma membrane, they bind to protein receptors that span the membrane and start signaling inside the cell. The response often depends on small messenger molecules such as cAMP or calcium ions. Many of these hormones use G protein-coupled receptors, or GPCRs. These membrane receptors connect to regulatory G proteins, which then activate enzymes such as adenylyl cyclase or...

target cell response to hormones

Hormone Receptors and Cell Response

Hormones trigger cell responses by binding to receptors on the cell surface or inside the target cell. This binding starts a chain of events that changes how the cell behaves. The response depends on the hormone, the receptor, and the type of target cell. Cells can also change how strongly they respond by adjusting receptor numbers. When a cell is exposed to high hormone levels for a long time, it may down-regulate receptors. Down-regulation means the cell makes fewer receptors for that...

regulation of hormone secretion

How Hormones Stay in Balance

Hormone secretion stays in balance through neural, humoral, and hormonal signals. These signals tell endocrine glands when to release hormones. Together, they help the body respond to changing conditions. Neural stimuli begin with environmental cues that trigger action potentials in nerve fibers. These nerve signals travel to their targets and can quickly start hormone release. A clear example is stress, when the sympathetic nervous system causes the adrenal glands to release epinephrine. This...

the pituitary gland

Pituitary Lobe Structure and Hormone Links

The pituitary gland is a small endocrine organ in the sphenoid bone, just under the hypothalamus. In adults, it has two main regions: the anterior lobe and the posterior lobe. During fetal development, a third region called the pars intermedia forms, but it atrophies and disappears. Some of its cells remain and are found next to the anterior pituitary in adults. The anterior lobe includes the pars distalis and the pars tuberalis. These regions are made of glandular epithelial tissue, which...

hormones of the pituitary gland

Pituitary Hormones and Their Body Roles

The pituitary gland is a small, pea-sized gland at the base of the brain. It helps regulate body functions such as growth and reproduction. The gland has two lobes, the anterior lobe and the posterior lobe. In the anterior lobe, secretory cell clusters in the pars distalis are controlled by hypothalamic regulators and produce six main hormones. Growth hormone is the most abundant hormone released from the anterior lobe. It supports overall growth by helping the body produce insulin-like growth...

the thyroid gland

Thyroid Follicles, Cells, and Hormones

The thyroid gland is a small, butterfly-shaped gland in the neck. It lies over the front surface of the trachea. The gland has two lateral lobes joined by a thin band of tissue called the isthmus. Inside each lobe are many small, round thyroid follicles. These follicles are surrounded by a network of blood vessels. Each follicle has a central cavity lined by simple cuboidal to squamous epithelial cells called follicular cells. Follicular cells make the glycoprotein thyroglobulin and store it...

synthesis and regulation of thyroid hormones

Thyroid hormones T3 and T4 are made through a step-by-step process in the thyroid gland. Their release is also controlled by a feedback loop that helps keep hormone levels balanced in the body. When blood levels of T3 and T4 drop, the hypothalamus responds by releasing thyrotropin-releasing hormone, or TRH. TRH travels to the pituitary gland and stimulates it to release thyroid-stimulating hormone, or TSH, into the bloodstream. TSH then acts on the thyroid gland. It stimulates the follicular...

functions of thyroid hormones

Thyroid Hormones in Growth and Metabolism

Thyroid hormones help control growth, metabolism, and body balance. They are essential during fetal life and childhood, when the skeletal, muscular, and nervous systems are developing and maturing. They also support bone mineral turnover and protein synthesis in growing tissues. In adulthood, thyroid hormones continue to affect the body in important ways. They help regulate gonadal hormone secretion, especially in females, and support endocrine tissue function. They also contribute to normal...

synthesis and functions of calcitonin

Calcitonin and Blood Calcium Control

Calcitonin is a polypeptide hormone that helps control calcium levels in body fluids. It is released by parafollicular cells, also called C cells, in the follicular epithelium of the thyroid gland. Calcitonin responds to changes in blood calcium levels. It is also influenced by gastrointestinal hormones such as gastrin and cholecystokinin. The exact mechanism of calcitonin in calcium homeostasis is still not fully clear. Even so, its role is important in several body processes. In childhood,...

the parathyroid glands

Parathyroid Hormone and Calcium Control

The parathyroid glands help control calcium balance in the body. These two pairs of glands sit on the posterior surface of the thyroid gland and are enclosed by a dense capsule. They contain two main cell types: principal cells and oxyphil cells. Principal parathyroid cells make parathyroid hormone, or PTH, also called parathormone. These cells sense when blood calcium levels fall. When calcium drops, they release PTH to start a response that helps restore calcium balance. PTH acts on bones,...

anatomy of the adrenal glands

Adrenal Glands and the Stress Response

The adrenal glands help the body respond to stress. These paired, pyramid-shaped glands sit above the kidneys and line up with the twelfth rib. They also have a yellow tint because they store cholesterol and fatty acids needed to make hormones. Each gland is wrapped in a fibrous capsule and cushioned by fat. Inside, the gland has two main regions with different jobs. The outer adrenal cortex makes corticosteroids, which support longer-lasting stress responses. The cortex is organized into...

hormones of the adrenal glands

Adrenal Cortex and Stress Hormones

Adrenal hormones help control electrolyte balance and the body’s stress response. They come from the adrenal cortex and the adrenal medulla, which work together to support survival and normal body function. The adrenal cortex makes over two dozen corticosteroid hormones. In the zona glomerulosa, the main mineralocorticoid is aldosterone. Mineralocorticoids help control the electrolyte makeup of body fluids. The zona fasciculata produces glucocorticoids such as cortisol and corticosterone.

adrenal gland disorders

Hormone Imbalances in the Adrenal Glands

Hormone imbalances in the adrenal glands can cause too little or too much hormone production. The adrenal glands make hormones that help control stress, blood pressure, and body balance. When these levels move away from normal, several adrenal disorders can develop. Adrenal insufficiency happens when the adrenal cortex makes too little cortisol and aldosterone. A common example is Addison’s disease. It can cause skin bronzing, dehydration, low blood pressure, fatigue, and weight loss.

the pineal gland

Melatonin and the Pineal Gland

The pineal gland is a small endocrine gland in the forebrain. It sits on top of the third ventricle in the diencephalon. It gets its pinecone-shaped name from its form. This gland is made of secretory cells called pinealocytes. These cells are arranged in tight cords and clusters around dense particles of calcium salts. The pineal gland mainly releases melatonin, a hormone made from serotonin. Melatonin levels in the blood follow a day-night cycle. Light exposure affects this pattern.

cells and secretions of the pancreas

Pancreatic Hormones and Digestive Cells

The pancreas uses two main kinds of cells to support digestion and blood sugar control. Its exocrine cells and endocrine cells work together to keep the body balanced. The pancreas is a glandular organ in the abdominal cavity, and it belongs to both the digestive and endocrine systems. Exocrine function comes from acinar cells, which are grouped into clusters called acini. These cells release large amounts of alkaline digestive juice that is rich in enzymes. This secretion helps support...

hormones regulating blood glucose

How Insulin and Glucagon Shift Energy

Insulin and glucagon are pancreatic hormones that help keep blood glucose levels in balance. Insulin is released by beta cells when blood glucose is high. Glucagon is released by alpha cells when blood glucose drops below normal. Insulin helps glucose move into insulin-dependent cells that have insulin receptors on their plasma membranes. It increases the number of glucose transport proteins in the cell membrane, which allows glucose to enter the cell more easily. This raises glucose use and...

diabetes mellitus: overview and type i subtype

diabetes-mellitus-overview-and-type-i-subtype

Diabetes Mellitus: Blood Sugar Control

Diabetes mellitus is a chronic metabolic disorder that raises blood glucose levels. It happens when the body does not make enough insulin, when cells do not respond well to insulin, or when both problems are present. This condition can affect health and quality of life in many people worldwide. Type 1 diabetes is an autoimmune disease. In this form, the immune system attacks and destroys the beta cells in the pancreas that produce insulin. Because of this damage, the body cannot make enough...

gonadal and placental hormones

Hormones in Sexual Development and Pregnancy

Gonadal and placental hormones guide sexual development, reproduction, and pregnancy. The gonads are the testes in males and the ovaries in females. They produce hormones that help control these body processes. In males, testosterone is the main gonadal androgen, or male sex hormone. It helps the penis and testes mature. It also drives secondary sex characteristics, such as a deeper voice and facial and pubic hair growth. Testosterone also supports sperm production. In females, estrogen and...

diabetes mellitus: type 2 and gestational

Type 2 Diabetes and Pregnancy Risks

Type 2 diabetes and gestational diabetes both involve problems with blood sugar control. In Type 2 diabetes, insulin resistance develops when insulin receptors on cells lose their response to insulin. This lowers the cell’s ability to take up glucose and leaves blood glucose levels high. Doctors use a series of blood glucose tests to diagnose Type 2 diabetes. These tests show whether blood glucose is in the normal range. If results are abnormal, a patient may be labeled prediabetic or...

key terms and concepts

Learn how the hypothalamus, pituitary gland, and thyroid work together to make T3 and T4, and how feedback helps control hormone levels.

How T3 and T4 Are Made and Controlled | JoVE K12

anatomy and physiology

JoVE Core Anatomy and Physiology showcases the anatomical and physiological details of the human body in comprehensive, clear, and engaging video animations. This collection of lessons focuses on the structures, components, functions, and requirements of the human body. It is complemented by scientist-in-action videos that demonstrate the application of this knowledge in real-world medical and research settings.

Florida Department of Education

High School

Life Science

SC.912.L.14

SC.912.L.14.32

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Nervous System

How T3 and T4 Are Made and Controlled

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