Lesson Video: Hormonal Control | Nagwa Lesson Video: Hormonal Control | Nagwa

Lesson Video: Hormonal Control Biology

In this video, we will learn how to describe the structure and function of the human endocrine system.

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Video Transcript

In this video, we will investigate the principles of hormonal control by exploring the structure and function of the human endocrine system. Then, we’ll try some practice questions together. And finally, we’ll review what we’ve learned. So, let’s make like the pituitary gland during puberty and get started.

Your endocrine system is one of about 11 organ systems that work together in a set of closely integrated interactions that carry out your life functions. Your endocrine system works closely with your nervous system to perform the essential function of control and integration of the other body systems.

The endocrine system plays its role in control and integration through the action of hormones. Hormones are chemical messengers that carry signals throughout your body. They are special molecules produced by your endocrine glands. Here’s a diagram of some of the major glands of your endocrine system. Here we have the pituitary glands, the thyroid, your adrenal glands, the pancreas, and the gonads — ovaries in females and testes in males. Each of your endocrine glands produces one or more hormones. And you’ll notice that the glands are scattered throughout your body. They don’t need to be clustered together like other organ systems because the glands secrete hormones, which are then carried in the bloodstream until they’re transported to their target cells. The target cells are the specific cells that bear receptor for or react to a specific hormone.

So, we’ve learned that your endocrine system consists of glands, which secrete hormones, which are then transported by your circulatory system to the target cells in the tissues and organs upon which they act. Next, let’s take a closer look at some of these glands, their hormones, and their actions.

This diagram shows a cross section of your brain. And here at the base of your brain nestled deep within your skull is the pituitary gland. The pituitary gland is very small, about the size of a green pea. But it’s often referred to as the master gland because it controls the actions of many other glands within your endocrine system. It produces many hormones, which generally act to stimulate other glands. The pituitary gland is well known for producing growth hormone, which, among other things, stimulates growth. That’s especially apparent during the growth spur experienced during puberty.

The next gland we’ll look at is your thyroid gland. The thyroid is located in your neck wrapped around your trachea. If you place your hand against your neck and swallow, you’ll feel a piece of cartilage move up and down. Your thyroid gland is located just below that piece of cartilage. The thyroid gland produces the hormone thyroxine, which is responsible for regulation of your metabolism. This means that your thyroid gland affects weight maintenance and energy levels.

The next gland we’ll look at are your adrenal glands. Each of us has two adrenal glands. And they sit on top of our kidneys like little hats. In fact, ad- is a prefix meaning near. And renal is a word that means kidneys. The adrenal glands most famously produce a hormone known as adrenaline. A large quantity of adrenaline released into the bloodstream can trigger something called a fight or flight response. The fight or flight response is a cascade of reactions that prepare the body to deal with sudden danger, reactions such as increased heart rate to pump more oxygen containing blood to your muscles and increased respiration rate to get more oxygen into your bloodstream, pupil dilation to let more light into your eyes, and several other reactions.

In this diagram, we see an organ known as your pancreas. This organ is tucked between your stomach and your liver. The pancreas is the largest of the endocrine glands. It also plays an important role in producing enzymes for your digestive system, but its primary endocrine function is to produce a hormone called insulin. Insulin’s main role is to regulate blood glucose concentration. This is especially important because, as you may recall, glucose is one of the reactants necessary for cellular respiration. And cellular respiration is a process that produces all of the energy that fuel our cells, which carry out all of our essential life functions.

The last glands that we need to take a look at are the gonads. In males, these are called testes. And the female gonads are called ovaries. The gonads produce hormones that play a role in the endocrine system, but they are also obviously essential to the reproductive system. The main hormones that they each produce are estrogen from the ovaries and testosterone from the testes. These hormones play an important role in development during puberty. And estrogen also influences the menstrual cycle in females.

Now that we’ve learned some of the basics of hormonal control, let’s take a closer look at a specific example.

Insulin is a hormone produced by your pancreas. And you may recall its main job is to regulate blood glucose concentration. Now, imagine that you’re enjoying a sweet, delicious slice of birthday cake. All of those tasty simple carbohydrates enter your bloodstream, and your blood glucose concentration begins to rise. Your pancreas detects the rise in blood glucose levels. It responds by producing insulin, which also enters your bloodstream. The insulin circulates in the bloodstream until it reaches its target cells. Here, we have a fat cell pictured. The insulin binds to the receptors on the target cells and causes them to take in the excess glucose. This reduces the glucose concentration in your bloodstream, and the unnecessary insulin is eventually removed.

If you enjoyed too many sugary snacks, two things can happen. Your cells may become resistant to insulin, meaning that the insulin in your blood stream will no longer cause the cells to take in the excess glucose or the cells of your pancreas may become damaged, causing them to produce less insulin. Either case can lead to a metabolic disease called type two diabetes. So, be sure to enjoy those sugary snacks sparingly.

Earlier, we started this video with a brief discussion of how the endocrine system and the nervous system work together to carry out the bodily function of control and integration of our other organ systems. Before we move on to our practice questions, we’ll take a moment to look at some of the similarities and differences in the mechanisms of control that the endocrine system and the nervous system utilize.

Well, we know that both the endocrine system and the nervous system are responsible for sending messages throughout your body and they’re both responsible for controlling and regulating other bodily functions. As we’ve learned in this video, your endocrine system achieves this through the use of glands, which secrete hormones, which are chemical messengers that are transported through your bloodstream. The bloodstream carries your hormones throughout your entire body until they reach the target cells upon which they act. For these reasons, the actions of your endocrine system are both slower and longer lasting than those of your nervous system.

In contrast, your nervous system controls and regulates your body through the actions of neurons or nerve cells. Your nerve cells communicate using impulses, which are electrical and chemical signals. These impulses travel to a specific target, which means that the signal is more localized. For these reasons, the actions of your nervous system tend to be faster but more short-lived than those of the endocrine system.

Now that we’ve learned about the endocrine system, glands, hormones, and their mechanisms of control, we’re ready to try some practice questions.

Which of the following best defines a hormone? (A) A hormone is a chemical messenger transported by the blood stream. (B) A hormone is an electrical messenger transported by the nervous system. (C) A hormone is a chemical messenger transported by the nervous system. Or (D) a hormone is an electrical messenger transported by the blood stream.

This question is asking us to read through the answer choices and choose the response that best describes a hormone. Hormones are a part of your endocrine system. So, we’ll review some key facts about the actions and mechanisms of your endocrine system in order to answer this question.

Your endocrine system is an organ system that consists of endocrine glands, an example of which is your pancreas. Endocrine glands are glands that secrete hormones. In this case, your pancreas secretes insulin. Hormones are chemical messengers that are transported throughout the body in the bloodstream. The hormones circulate until they reach their target cells upon which they act. With this information in mind, we’re ready to choose our answer. A hormone is a chemical messenger transported by the blood stream.

Let’s try a second practice question.

The diagram shows a basic outline of the major endocrine glands in the body. What endocrine gland is represented by label A? What endocrine gland is represented by label B? What endocrine gland is represented by label C? And what endocrine gland is represented by label D?

This question provides us with a diagram of our major endocrine glands and then asks us to identify them based on appearance and location. To answer this question, we’ll simply identify what’s been labeled in this image, and then we’ll go ahead and respond to each of the prompts.

I’ve added some hints to the diagram that may help you recall the name of each of these glands. First, we have the gland known as the master gland because it tends to act on the other glands of the endocrine system. This gland is located deep within the base of your brain. It’s called your pituitary gland.

Our next gland produces a hormone called thyroxine. Thyroxine is a hormone that helps to control our metabolism. It also sounds a little bit like the name of this gland, which is your thyroid.

Next, we have a pair of glands known for making adrenaline. The name of these glands means “near the kidneys,” which is appropriate since they sit right on top of them. These are your adrenal glands.

Finally, we have the largest gland in your endocrine system. It’s known for producing the hormone insulin. And insulin regulates your blood glucose concentration. This very important gland is your pancreas.

Now, let’s answer our questions. The endocrine gland represented by label A is the pituitary gland. The endocrine gland represented by label B is the thyroid. The endocrine gland represented by label C is an adrenal gland. And the endocrine gland represented by label D is the pancreas.

Finally, let’s take a moment to review what we’ve learned. In this lesson, we’ve learned that glands secrete hormones. Hormones are transported by the blood stream to the target cells, tissues, or organs upon which they act. We also reviewed the major glands of the endocrine system and the hormones that they produce.

The pituitary gland, also known as the master gland, is known for producing growth hormone. The thyroid produces a hormone called thyroxine. Your adrenal glands produce a hormone known as adrenaline. Your pancreas, very importantly, produces insulin. The gonads are reproductive organs that also play a role in the endocrine system. In females, you find ovaries, which produce estrogen. And in males, you find the testes, which produce testosterone.

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