Name: endocrine glands and hormone sources
Uploaded: 2024-03-28T14:28:47.000Z
Duration: 59 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

Structures of the Endocrine System

El sistema endocrino está compuesto por glándulas, tejidos y órganos distribuidos por todo el cuerpo.
Las glándulas endocrinas son glándulas sin conductos que secretan hormonas en el líquido intersticial.
El hipotálamo es un órgano neuroendocrino del cerebro que regula las funciones neuronales además de secretar hormonas. La glándula pituitaria y la glándula pineal están cerca del hipotálamo.
Las glándulas tiroides y paratiroides se encuentran en el cuello, y el timo se encuentra en la región superior del tórax
Las glándulas suprarrenales están por encima de los riñones, y las gónadas, los testículos en los hombres y los ovarios en las mujeres, producen hormonas reproductivas.
El páncreas, ubicado cerca del estómago, puede actuar como una glándula endocrina para ayudar a mantener los niveles de glucosa y una glándula exocrina para ayudar con la digestión.
Además, las células de varios órganos y tejidos, como el corazón, el tejido adiposo, la piel y la placenta, también pueden liberar señales endocrinas.

estructuras del sistema endocrino

La intrincada estructura del sistema endocrino abarca una amplia gama de glándulas, con sus tejidos y órganos diana estratégicamente distribuidos por todo el cuerpo. En el centro de esta red se encuentran las glándulas endocrinas, estructuras especializadas que carecen de conductos y liberan hormonas directamente en el líquido intersticial. En particular, el hipotálamo, un órgano neuroendocrino vital situado en el cerebro, gobierna las funciones neuronales y sirve como una potente fuente de regulación hormonal. Cerca del hipotálamo se encuentran las glándulas pituitaria y pineal en la región de la cabeza.

Las glándulas tiroides y paratiroides en la región del cuello desempeñan funciones fundamentales en el metabolismo y la homeostasis del calcio, respectivamente. En la parte superior del pecho, el timo influye en el desarrollo del sistema inmunológico. Las glándulas suprarrenales están situadas encima de los riñones. Contribuyen a la respuesta al estrés y al equilibrio electrolítico. Las gónadas, que comprenden los testículos en los hombres y los ovarios en las mujeres, generan hormonas reproductivas.

Además, el páncreas, ubicado cerca del estómago, muestra versatilidad al funcionar como glándula endocrina que regula los niveles de glucosa y como glándula exocrina que ayuda a la digestión. Más allá de estas glándulas reconocidas, las células de diversos órganos y tejidos (incluidos el corazón, el tejido adiposo, la piel y la placenta) pueden liberar señales endocrinas, expandiendo la influencia del sistema en los diversos dominios fisiológicos del cuerpo. Esta intrincada distribución espacial subraya la naturaleza holística del sistema endocrino, que trabaja en conjunto para mantener el equilibrio y la coordinación en todo el organismo.

Estructuras del sistema endocrino

El sistema endocrino está compuesto por glándulas, tejidos y órganos distribuidos por todo el cuerpo.
Las glándulas endocrinas son glándulas sin conductos que secretan ...

Education

Educación

JoVE Core

Anatomy and Physiology

Anatomía y Fisiología

Unit 1

Unidad 1

The Endocrine System

El sistema endocrino

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

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 gland in the head. The thyroid and parathyroid glands are in the neck. The thyroid helps control metabolism, while the parathyroid glands help with calcium balance.

Other endocrine organs are found lower in the body. The thymus in the upper chest supports immune system development. The adrenal glands sit above the kidneys and help with stress response and electrolyte balance. The gonads, which are the testes in males and ovaries in females, make reproductive hormones. The pancreas lies near the stomach and has two roles. It acts as an endocrine gland to regulate glucose levels and as an exocrine gland to help digestion.

Endocrine signals also come from cells in other organs and tissues. The heart, adipose tissue, skin, and placenta can all release hormone signals. This wider network shows that the endocrine system is spread throughout the body. Together, these glands and hormone-producing tissues help maintain balance and coordination in the organism.

Endocrine Glands and Hormone Sources

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

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

synthesis-and-regulation-of-thyroid-hormones

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...

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

Explore the main endocrine glands, where they are found in the body, and how they release hormones to support metabolism, stress response, growth, and reproduction.

Endocrine Glands and Hormone Sources | 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.14.29

SC.912.L.14.30

SC.912.L.14.32

Organization of the Nervous System

The nervous system is the primary control and communication center of the body.
The nervous system can be divided into two major categories&#8212;the ...

functional-divisions-of-the-nervous-system

Functional Divisions of the Nervous System

The nervous system senses, integrates, and responds to various stimuli. Based on bodily control, the central nervous system cannot be divided ...

Functions of the Nervous System

The nervous system has three main functions: sensation, integration, and motor output.
Sensory functions detect and process stimuli from external and ...

Neurons: The Cell Body and the Dendrites

A typical nerve cell comprises three main components: the cell body, dendrites, and the axon. The cell body, also known as the soma or perikaryon, serves ...

Neurons: The Axon

The axon is a long, thin extended portion of the neuron that carries impulses from its cell body toward the effector cell.
Axoplasm, the axon&#39;s ...

Nervous Tissue: Neuron Types

Neurons, the fundamental units of the nervous system, can be classified based on both their structural and functional characteristics.
Structurally, ...

Nervous Tissue: Glial Cells

Glial cells or neuroglia are non-neuronal cells in the nervous system that outnumber neurons. These include astrocytes, oligodendrocytes, microglia, and ...

Nervous Tissue: Myelin

Myelin is a protective, multilayered covering around axons, composed of lipids and proteins, that provides electrical insulation.
In the PNS, individual ...

electrochemical-gradient-and-channel-proteins-an-overview

Electrochemical Gradient and Channel Proteins: An Overview

An electrochemical gradient is a fundamental concept in biology and chemistry. It regulates the movement of ions across cell membranes. This movement is ...

Ligand-gated Ion Channels

Voltage-gated Ion Channels

Mechanically-gated Ion Channels

Resting Membrane Potential

Resting Potential Decay

Graded Potential

Graded potentials are localized fluctuations in the cell membrane&#39;s electrical charge, commonly found in the dendrites of neurons. The magnitude of ...

Action Potential: Phases of Stimulation

The action potential is a complex electrical event that occurs in excitable cells, such as neurons and muscle cells. It consists of several distinct ...

Anatomy of the Brain: Major Regions

The human brain is a complex organ consisting of four main parts &#8212; the cerebrum, the cerebellum, the diencephalon, and the brainstem.
The cerebrum ...

Propagation of Action Potentials

The Propagation of an action potential is the process by which a nerve impulse is transmitted along the axon. It is a self-propagating process; once ...

Anatomy of the Brain: Ventricles

Deep inside the human brain are the hollow fluid-filled cavities called ventricles.
There are two lateral ventricles, one in each cerebral hemisphere.
...

Overview of Synapses

Synapse is a region where communication occurs between two neurons or a neuron and its effector cell. The neuron that carries the impulse toward the ...

Cerebrum: Anatomical Overview I

The cerebrum is the largest part of the brain. It is divided into two cerebral hemispheres.
The outer area of each hemisphere &#8212; the cerebral cortex ...

Chemical Synapses

Chemical synapses are specialized sites between two neurons or between a neuron and a non-neuronal cell like a muscle, glandular or sensory cell.
Because ...

Cerebrum: Anatomical Overview II

Each cerebral hemisphere has three basic regions.
The outermost region is called the cerebral cortex. It is a 2 to 4 mm thick layer of gray matter ...

Neurotransmitters

Neurotransmitters play a crucial role in the communication between neurons in the autonomic nervous system. Neurons in the autonomic nervous system can be ...

Motor and Sensory Areas of the Cortex

The cerebral cortex has three functional areas &#8212; the motor, sensory, and association areas.
The motor areas, located in the frontal lobe, control ...

Postsynaptic Potential (PSP)

Postsynaptic potential or PSP refers to a change in the electrical potential of a postsynaptic membrane when neurotransmitters released by presynaptic ...

Association Areas of the Cortex

Association areas are regions of the cerebral cortex that do not have a specific sensory or motor function. Instead, they integrate and interpret ...

Integration of Synaptic Events

The integration of synaptic events involves the summation of multiple graded potentials, such as excitatory and inhibitory postsynaptic potentials, at the ...

Diencephalon: Anatomical Regions

The diencephalon is situated above the brainstem, concealed by the cerebral hemispheres.
It is majorly made up of three paired structures &#8212; the ...

Neural Circuits

In the central nervous system, billions of interconnected neurons are organized into specialized functional groups called neuronal pools.
Within each ...

diencephalon-thalamus-and-information-relay

Diencephalon: Thalamus and Information Relay

The thalamus consists of several groups of paired nuclei, each acting as a relay station to channel the information from specific brain parts into the ...

neurogenesis-and-regeneration-of-nervous-tissue

Neurogenesis and Regeneration of Nervous Tissue

In the CNS, neurogenesis, the birth of new neurons from stem cells, is limited to the hippocampus in adults. In other regions of the brain and spinal ...

diencephalon-hypothalamus-and-coordination

Diencephalon: Hypothalamus and Coordination

The hypothalamus receives somatic and visceral inputs and controls various physiological activities.
It consists of several nuclei organized into four ...

Disorders of the Nervous Tissue

Nervous tissue disorders are caused by several factors.
Homeostatic imbalances include cerebral hypoxia&#160; &#8212; or reduced oxygen supply to the ...

Cerebellum: Anatomical Regions

The cerebellum is positioned inferior to the posterior part of the cerebrum.
As seen in the posterosuperior view, a thin median structure called the ...

Brainstem

The brainstem comprises three regions&#8212;the midbrain, pons, and medulla oblongata.
The midbrain is situated below the diencephalon and has two bulging ...

Cranial Nerves: Types Part II

The facial nerve emerges from the pons and innervates the facial muscles, lacrimal glands, tongue, and salivary glands. It is a mixed nerve that controls ...

Brainstem: Control Centers of Medulla

The medulla oblongata is a critical region of the brainstem. It contains several nuclei having vital functions.
The lateral side of each pyramid has a ...

Spinal Nerves: Anatomy

Spinal nerves are pivotal conduits in the nervous system, bridging the central nervous system (CNS) with the peripheral nervous system (PNS). These nerves ...

Functional Brain Systems: Limbic System

The limbic system is a functional brain region consisting of specific parts of the diencephalon and cerebrum.
The limbic lobe of the cerebral cortex ...

Spinal Nerves: Plexus I

A plexus is an axon network of the anterior rami of nerves from different spinal regions, except for thoracic nerves T2 to T12, which form the intercostal ...

functional-brain-systems-reticular-formation

Functional Brain Systems: Reticular Formation

The reticular formation is a complex network of gray and white matter spread across the core of the brainstem.
It is roughly divided into three paired ...

Spinal Nerves: Plexus II

The lumbar, sacral, and coccygeal plexuses serve the lower body.
The lumbar plexus is mainly composed of the first four lumbar spinal nerves, that branch ...

Spinal Cord: Gross Anatomy

Inside the vertebral column is the slender and tubular structure called the spinal cord.
It is shorter than the vertebral column, with a length of about ...

Cranial and Spinal Meninges

The brain is wrapped by three membranes called meninges.
The outermost cranial dura mater has the periosteal layer adhering to the inner skull surface and ...

Nervous System

Content elaboration: The nervous system consists of neurons and supporting cells that combine to form nerves, the spinal cord and the brain. The primary functions of the nervous system are sensation, integration and response. A comparison of the structures and functions of the central and peripheral nervous systems should be explored. The central nervous system is composed of the brain and spinal cord. The peripheral nervous system includes the remaining nervous tissue. A neuron consists of dendrites, a cell body and an axon. Neurons conduct electrical impulses along their membranes and at synapses. Brain cells can detect and sometimes respond to these impulses. Neuroglial cells help to support neural function. The brain consists of three major parts: the cerebrum, cerebellum and brainstem. The cerebrum is divided into lobes and hemispheres. Functions of the cerebrum that may be explored include voluntary muscle control, memory, sensory perception, emotions and speech. The cerebellum is primarily responsible for balance and coordination. The brainstem, a part of the autonomic nervous system, includes structural divisions that perform basic life functions such as breathing and heart rate. The spinal cord is a continuation of the brainstem. The spinal cord is a bundle of nerve tracts that transmits nerve signals between the brain and the body through electrical impulses. Nerves are bundles of neurons that transmit impulses between the peripheral and central nervous systems. The study of nerves can include sciatic, cranial and spinal nerves. Supporting structures of the central nervous system include the meninges and cerebrospinal fluid which protect the central nervous system. Processes of the nervous system are action potential propagation, simple nerve pathways (reflex arc) and neurotransmitter function. Homeostatic imbalances are explored. These include, but are not limited to, the effects of drugs, mental illnesses, spinal injuries, concussions, meningitis and multiple sclerosis (MS). Investigations are used to understand and explain the nervous system in a variety of inquiry and design scenarios that can incorporate evolutionary concepts, scientific reasoning, comparative analysis, communication skills and real-world applications.

Nervous System

Endocrine Glands and Hormone Sources

Description

Transcript

Tags

More videos by Standards