Learning objectives
By the end of this unit, you will be able to:
- Distinguish the types of intercellular communication, their importance, mechanisms and effects
- Identify the major organs and tissues of the endocrine system and their location in the body
Communication is a process in which a sender transmits signals to one or more receivers to control and coordinate actions. In the human body, two main organ systems engage in relatively "long distance" communication: the nervous system and the endocrine system. Together, these two systems are primarily responsible for maintaining homeostasis in the body.
Neural and Endocrine Signaling
The nervous system uses two types of intercellular communication - electrical and chemical signaling - either through the direct action of an electrical potential, or in the latter case, through the action of chemical neurotransmitters such as serotonin or norepinephrine. Neurotransmitters act locally and quickly. When an electrical signal in the form of an action potential reaches the synaptic terminal, it spreads across the synaptic cleft (the gap between a sending neuron and a receiving neuron or muscle cell). Once neurotransmitters interact (bind) with receptors on the receiving (postsynaptic) cell, stimulation of the receptor is converted into a response such as ongoing electrical signaling or modulation of cellular response. The target cell responds within milliseconds of receiving the chemical "message." This response then stops very quickly once the nerve signaling ends. In this way, neural communication enables body functions that involve quick, brief actions, such as movement, sensation, and cognition.endocrine systemuses only one method of communication: chemical signaling. These signals are sent by the endocrine organs, which secrete chemicals—thehormone— in the extracellular fluid. Hormones are transported primarily through the bloodstream throughout the body, where they bind to receptors on target cells, causing a characteristic response. As a result, endocrine signaling takes longer than neural signaling to elicit a response in target cells, although the exact time varies with different hormones. For example, the hormones released when faced with a dangerous or fearful situation, called the fight-or-flight response, are triggered by the release of adrenal hormones—epinephrine and norepinephrine—within seconds. In contrast, it can take up to 48 hours for target cells to respond to certain reproductive hormones.
Interactive link
Visit thisLinkto watch an animation of the events that occur when a hormone binds to a cell membrane receptor. What is the second messenger generated by adenylyl cyclase during activation of liver cells by epinephrine?
Furthermore, endocrine signaling is usually less specific than neural signaling. The same hormone can play a role in a variety of different physiological processes depending on the target cells involved. For example, the hormone oxytocin promotes uterine contractions in laboring women. It is also important in breastfeeding and may be involved in sexual response and feelings of emotional attachment in both men and women.
In general, the nervous system involves rapid responses to rapid changes in the external environment, and the endocrine system usually acts more slowly—taking care of the body's internal environment, maintaining homeostasis, and controlling reproduction.Table 17.1). So how does the fight-or-flight response mentioned earlier happen so quickly if hormones normally act more slowly? It is because the two systems are connected. It is the rapid action of the nervous system in response to danger in the environment that stimulates the adrenal glands to secrete their hormones. As a result, the nervous system can trigger rapid endocrine responses to keep pace with sudden changes in both the external and internal environment when necessary.
Endocrine and Nervous System
| Endocrine system | Nervous system | |
|---|---|---|
| Signaling mechanism(s). | Chemical substance | Chemical/electrical |
| Primary chemical signal | hormones | Neurotransmitters |
| Διανυθείσα απόσταση | Long or short | Always short |
| Response time | Fast or slow | Always fast |
| Environmental targeting | Internal | Internal and external |
Table 17.1
Structures of the Endocrine System
The endocrine system consists of cells, tissues, and organs that secrete hormones as a primary or secondary function. Theendocrine glandis the most important player in this system. The primary function of these ductless glands is to secrete their hormones directly into the surrounding fluid. The interstitial fluid and blood vessels then carry the hormones throughout the body. The endocrine system includes the pituitary gland, thyroid, parathyroid, adrenal glands, and pineal gland (Figure 17.2). Some of these glands have endocrine and non-endocrine functions. For example, the pancreas contains cells that function in digestion as well as cells that secrete the hormones insulin and glucagon, which regulate blood glucose levels. The hypothalamus, thymus, heart, kidneys, stomach, small intestine, liver, skin, female ovaries, and male testes are other organs that contain cells with endocrine function. Additionally, adipose tissue has long been known to produce hormones, and recent research has revealed that even bone tissue has endocrine functions.
Image17.2 Endocrine system Endocrine glands and cells are found throughout the body and play an important role in homeostasis.
Endocrine glands without ducts should not be confused with those of the bodyexocrine system, whose glands release their secretions through ducts. Examples of exocrine glands include the sebaceous and sweat glands of the skin. As just mentioned, the pancreas also has an exocrine function: most of its cells secrete pancreatic juice through the pancreatic and accessory ducts into the lumen of the small intestine.
Other types of chemical signaling
In endocrine signaling, hormones secreted into the extracellular fluid diffuse into the blood or lymph and can then travel long distances throughout the body. In contrast, autocrine signaling takes place within the same cell. Oneautocrine(auto- = "self") is a chemical that causes a response in the same cell that secretes it. Interleukin-1, or IL-1, is a signaling molecule that plays an important role in the inflammatory response. Cells that secrete IL-1 have receptors on their cell surface that bind these molecules, resulting in autocrine signaling.
Local intercellular communication is his provinceparacrine, also called a paracrine factor, which is a chemical that causes a response in neighboring cells. Although paracrine can enter the bloodstream, their concentration is generally too low to elicit a response from distant tissues. An example familiar to those with asthma is histamine, a paracrine released by immune system cells in the bronchial tree. Histamine causes bronchial smooth muscle cells to contract, narrowing the airways. Another example is the neurotransmitters of the nervous system, which act only locally within the synaptic cleft.
Career Connection
Endocrinologist
Endocrinology is a specialty in the field of medicine that focuses on the treatment of disorders of the endocrine system. Endocrinologists - doctors who specialize in this field - are experts in treating diseases related to hormone systems, ranging from thyroid disease to diabetes mellitus. Endocrinological surgeons treat endocrine diseases by removing or resecting the affected endocrine gland.
Patients referred to endocrinologists may have signs and symptoms or blood test results that suggest over- or under-functioning of an endocrine gland or endocrine cells. The endocrinologist may order additional blood tests to determine whether the patient's hormone levels are abnormal or may be stimulating or suppressing the function of the suspected endocrine gland, and then draw blood for analysis. Treatment varies depending on the diagnosis. Some endocrine disorders, such as type 2 diabetes, may respond to lifestyle changes such as moderate weight loss, adopting a healthy diet and regular physical activity. Other disorders may require medication such as hormone replacement and regular monitoring by an endocrinologist. These include disorders of the pituitary gland that can affect growth and disorders of the thyroid gland that can lead to a variety of metabolic problems.
Some patients experience health problems as a result of the normal decline in hormones that can accompany aging. These patients may consult an endocrinologist to weigh the risks and benefits of hormone replacement therapy aimed at boosting their natural levels of reproductive hormones.
In addition to treating patients, endocrinologists may be involved in research to improve understanding of disorders of the endocrine system and develop new treatments for these diseases.
FAQs
What is the overview of the endocrine system anatomy? ›
The endocrine system is a complex network of glands and organs. It uses hormones to control and coordinate your body's metabolism, energy level, reproduction, growth and development, and response to injury, stress, and mood.
What is the endocrine system human anatomy and physiology? ›The endocrine system is made up of glands that produce and secrete hormones, chemical substances produced in the body that regulate the activity of cells or organs. These hormones regulate the body's growth, metabolism (the physical and chemical processes of the body), and sexual development and function.
What is the endocrine system high school anatomy and physiology? ›The endocrine system consists of cells, tissues, and organs that secrete hormones as a primary or secondary function. The endocrine gland is the major player in this system. The primary function of these ductless glands is to secrete their hormones directly into the surrounding fluid.
What are the 4 main functions of the endocrine system? ›Your endocrine system: Makes hormones that control your moods, growth and development, metabolism, organs, and reproduction. Controls how your hormones are released.
What are the 3 main parts of the endocrine system? ›Although the endocrine system is made up of many parts, the three major ones include the pituitary gland, the hypothalamus, and the thyroid gland.
What are the 5 major parts of the endocrine system? ›- Hypothalamus. The hypothalamus is located at the base of the brain, near the optic chiasm where the optic nerves behind each eye cross and meet. ...
- Pineal body. ...
- Pituitary. ...
- Thyroid and parathyroid. ...
- Thymus. ...
- Adrenal gland. ...
- Pancreas. ...
- Ovary.
Important endocrine glands include the pituitary, thyroid, parathyroid, thymus, and adrenal glands.
What is the study of endocrine and its physiology known as? ›Endocrinology – Study of the Hormonal Regulation of the Body
Endocrinology is the branch of biology and medicine that studies normal production and functions of hormones and their disturbances.
Stimulate glands, regulate growth, regulate metabolism, maintain fluid + chemical balance, and control various sex processes.
What is the endocrine system quizlet? ›the endocrine system is made up of glands that produce and secrete hormones that regulate the activity of cells or organs. These hormones regulate the body's growth, metabolism (the physical and chemical processes of the body), and sexual development and function.
What is the endocrine system anatomy nursing? ›
The endocrine system assists in managing the heart rate and blood pressure and aids in preparing the body for physical motion. Immune system control. The endocrine system helps regulate the production and functions of immune cells. Reproductive function controls.
What are the 7 major organs of the endocrine system? ›The endocrine system includes the hypothalamus, pineal gland, pituitary gland, thyroid gland, parathyroid glands, thymus, adrenal glands, and pancreas.
What are 4 structures in the endocrine system? ›The endocrine system includes the pituitary, thyroid, parathyroid, adrenal, and pineal glands (Figure 14.1. 1). Some of these glands have both endocrine and non-endocrine functions.
Why is the endocrine system so important? ›The hormones created and released by the glands in your body's endocrine system control nearly all the processes in your body. These chemicals help coordinate your body's functions, from metabolism to growth and development, emotions, mood, sexual function and even sleep.
What is endocrine system and its function? ›The endocrine system is a network of glands and organs located throughout the body. It's similar to the nervous system in that it plays a vital role in controlling and regulating many of the body's functions.
Which best describes the endocrine system? ›Answer and Explanation: The statement that best describes the endocrine glands is b. They secrete hormones that regulate the body's activity. Unlike exocrine glands, endocrine glands produce hormones which are chemical signals and will release these into the bloodstream.
How many glands does the endocrine system have? ›The endocrine system is made up of seven different glands that make chemicals called hormones. Hormones are substances that act as "messengers" to control many body functions. The endocrine system makes hormones that help control: Growth.
What is the most important gland in the endocrine system? ›The pituitary gland is sometimes called the "master" gland of the endocrine system because it controls the functions of many of the other endocrine glands.
What are the 20 endocrine glands? ›- Endocrine Glands. Unlike exocrine glands(sweat, salivary), endocrine glands secrete their respective substances directly into the bloodstream rather than through a duct. ...
- Pituitary gland. ...
- Thyroid gland. ...
- Parathyroid glands. ...
- Adrenal glands. ...
- Pancreas. ...
- Gonads. ...
- Pineal gland.
The endocrine system, made up of all the body's different hormones, regulates all biological processes in the body from conception through adulthood and into old age, including the development of the brain and nervous system, the growth and function of the reproductive system, as well as the metabolism and blood sugar ...
Why is it called the endocrine system? ›
The endocrine glands do not have ducts to carry their product to a surface. They are called ductless glands. The word endocrine is derived from the Greek terms "endo," meaning within, and "krine," meaning to separate or secrete.
What is one function of the endocrine system psychology? ›The endocrine system works alongside the nervous system. It is a network of glands across the body that secrete chemical messages called hormones. Instead of using nerves (sensory and motor neurons) to transmit information, this system uses blood vessels. Different hormones produce different effects (behaviours).
What are the 9 endocrine glands? ›- hypothalamus.
- pituitary.
- thyroid.
- parathyroids.
- adrenals.
- pineal body.
- the ovaries.
- the testes.
- Menopause.
- Diabetes.
- Addison's disease.
- Cushing's disease.
- Graves' disease.
- Hashimoto thyroiditis.
- Hyperthyroidism/hypothyroidism.
- Prolactinoma.
An organ that makes hormones that are released directly into the blood and travel to tissues and organs all over the body. Endocrine glands help control many body functions, including growth and development, metabolism, and fertility. Some examples of endocrine glands are the pituitary, thyroid, and adrenal glands.
What are the major functions of the endocrine system quizlet? ›The endocrine system's main function is to regulate short-term and long-term activities by sending hormones throughout the body. The relationship between homeostasis and the endocrine system is that the glands in the body produce specific hormones that help the body maintain a balance.
What does the pituitary gland do? ›Anatomy of the Pituitary Gland
It regulates growth, metabolism, and reproduction through the hormones that it produces. The production of these hormones is either stimulated or inhibited by chemical messages sent from the hypothalamus to the pituitary. The posterior lobe produces two hormones, vasopressin and oxytocin.
The endocrine glands in the human body are hypothalamus, testes, ovary, pancreas, thyroid, pituitary, pineal, parathyroid, thymus and adrenal gland. The liver does not secrete any hormone.
What is the conclusion of endocrine system? ›Conclusion. Endocrine system is indispensible for life in addition to the nervous system. Fundamental biological functions such as reproduction, growth, salt-water balance and emergency responses such as fight or flight are regulated to a fine tuning by the endocrine system in young and adulthood.
What is the overview of endocrine disorders? ›An endocrine disorder results from the improper function of the endocrine system, which includes the glands that secrete hormones, the receptors that respond to hormones and the organs that are directly impacted by hormones. At any one of these points, dysfunction can occur and cause wide-ranging effects on the body.
What is the summary of endocrine system psychology? ›
The study of psychology and the endocrine system is called behavioral endocrinology, which is the scientific study of the interaction between hormones and behavior. This interaction is bidirectional: hormones can influence behavior, and behavior can sometimes influence hormone concentrations.
What is the endocrine system terms and definitions? ›Endo means within or inward. Crine means endocrine secretion. The endocrine system consists of a series of organs and glands throughout the body that produce, store, and secrete special chemical messengers. Gland. Glands are where hormones are produced and secreted into the bloodstream.
What is the function of the endocrine system? ›The endocrine system, made up of all the body's different hormones, regulates all biological processes in the body from conception through adulthood and into old age, including the development of the brain and nervous system, the growth and function of the reproductive system, as well as the metabolism and blood sugar ...
Why is endocrinology important? ›Endocrinology is an extremely important specialty in the medical profession. By effectively regulating the body's hormone production, energy levels, mood, and metabolism can all properly function.
How to understand endocrine physiology? ›The endocrine system is a control system of ductless glands that secrete hormones within specific organs. Hormones act as "messengers," and are carried by the bloodstream to different cells in the body, which interpret these messages and act on them.
Why is it important to study the endocrine system in psychology? ›The endocrine system is important because it influences every function of the body. It controls growth and development during childhood, energy, reproduction, immunity, and behavior.
What are the 5 hormones of the endocrine system? ›- Insulin. The fat-storage hormone, insulin, is released by your pancreas and regulates many of your metabolic processes. ...
- Melatonin. ...
- Estrogen. ...
- Testosterone. ...
- Cortisol.
The endocrine system is made up of the endocrine glands that secrete hormones. Although there are eight major endocrine glands scattered throughout the body, they are still considered to be one system because they have similar functions, similar mechanisms of influence, and many important interrelationships.