Janine Luker Student Identification: 22840848 June 27, 2009 Endocrinology Assignment/Personal Review and Summary Endocrinology is the study of hormones, the receptors in your body, and the signaling they give to release hormones in your body. The definition for endocrinology is defined in many different ways, but with all related meanings that sum up to the physiology of the endocrine glands. The endocrine system sends messages to the endocrine glands in your body that include the adrenal, pituitary, thyroid, and parathyroid glands, as well as, the hypothalamus, pancreas, ovaries, and testes.

There are two main systems in the body that control the proper functioning of the body. The nervous system sends ultra fast electrical alerts and messages from the brain. It is divided up into two main systems, the central nervous system and peripheral nervous system. The nervous system is responsible for collecting information from the body, and sending out instructions from the brain back to the body. The endocrine system sends information by secretions into the blood to receptors in the body. These two main systems may also at times work together for peak physiological performance.

The endocrine system is helpful in controlling certain functions in the human body. The substances help control metabolism, hormone reproduction, growth and development, and various other activities required for adequate survival. The hormones secreted can also help provide appropriate amount of nutrition and energy needed for your body to function well even with varying situations that hinder the body, such as missed meals or a change in the environment. The endocrine system plays a very vital role in the human body.

The hormones that are in your body are excreted into your blood from cells or organs that circulate in your blood, and can affect the functioning of other cells or organs. There are certain cells that are called target cells because they contain a receptor for the hormone that can then interact influentially with the hormones. This is necessary for communication within the endocrine system. Three actions define the pathway for a signal in the system. The first of these actions is the known as the endocrine action. This action happens when a hormone is secreted into the bloodstream and binds to the ells with receptors, the target cells. This allows for the communication to begin for the second action to be taken, the paracrine action. In this next phase, the hormone disperses from the initial cell to other neighboring cells creating the final step called the autocrine action. This allows the hormone to now perform with the originating cell that it was introduced by. Hormones can change the target cells after it becomes bound, undergoing a change that allows it to communicate with the various components of those cells that, then will inevitably lead to a change in the physical state affecting transcription.

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Molecules that bind to areas of the receptors can either be called agonists or antagonists. Agonists are molecules that produce post-receptor events that will eventually lead to a biological event in the body. Antagonists block the binding of the antagonists without creation of any events that signal extra cellular events. Antagonists can be used widely for the use of drugs, and hormone therapy. Agonists can also play a role in this as well. Hormones can be divided up into four categories, and share basic properties alike.

Proteins and peptides being one group that share a certain amount of responsibility. Peptides are polymers that are created by a linkage of amino acids. They function as signaling molecules, and as hormones in a higher functioning organism. The proteins are contained in a linear chain link that also makes up amino acids. They work together to achieve certain functions. They can also work to form stable complexes. Proteins are necessary and are essential for participation in almost every single process that takes place within a cell.

Enzymes that are considered a type of protein are vital for metabolism in the endocrine system. Another set of hormones are steroids. They are commonly known lipids, but classified as a terpenoid lipid with four individually fused rings. They can also be classified by their chemical composition. Steroids are derivatives of cholesterol. Estrogen, cortical, progesterone, testosterone are inclusive with steroids. These steroids have functioning roles within the endocrine glands. They are produced when certain reactions happen within the body including, pregnancy.

Steroid synthesis from cholesterol to pregnenolone happens within mitochondrion. Steroidogenesis occurs when there is a transformation from other steroids in the body. Products of steroidogenesis are estrogens, androgens, corticoids (glucocorticoids and mineralocorticoids), and progesterone. These are the five groups that make up steroid hormones, divided because they all bind to different receptors. A third group of hormone, the amino acid derivatives, contains two more groups derived from tyrosine. One of those groups, catecholamines, are used as neurotransmitters, and hormones.

Histamine is a amino acid histidine. Histamine is better known for its capabilities as a allergen blocker. It has now been found to be effective in many pathologic processes. The fourth group of hormones is the fatty-acid derivatives, eicosanoids. This group is generally very rapidly metabolized, thus offering a very short life span. However, arachidonic acid is generated for signaling purposes, and also is a critical omega-6 polyunsaturated fatty acid which is said to have ability to help muscle growth. It’s the body’s principle resource for production of prostaglandins.

It is known that hormones controlled at a proper level are good in prevention of certain diseases. Foe the most part, the body can regulate the growth and degradation of hormones, but hormone therapy is becoming more and more popular as certain factors in one’s lifestyle changes the control of endocrine activity. Feedback in the body is absolutely necessary to the physiology of the body. When negative feedback has been triggered, the body is able to respond to this creating a solution specific to the feedback provided.

Positive feedback enforces the job being done, and allows for the body to know to continue on the same track. There are many things that will changes in the body, but the feedback is a must for the human body to sustain itself. Without it, there would be a lack of direction inside an organism, and chaos would ensue. Feedback also helps to regulate many functions that are crucial for proper functioning. There are problems that occur due to feedback control, but namely because of the life spans that govern hormone concentration. The mechanisms of hormone action define what physiological action is taken next.

There are several different processes that make this mechanism up, but understanding it can help general science in many useful ways, including treatment diseases that bear itself in the endocrine system. Other mechanisms of action signal transduction or 2nd messengers trigger a change in the cells creating amplification to the hormone that change the physical state of the cell. This mechanism of process is beneficial for eccrinology. The amplification provides useful response to the initial pathway invoked. This second messenger provides ertinent intercellular interactions and concentration of nucleotides, and kinase activity, in which, insulin is a byproduct. More importantly, the normality of a variety of cell productions depends on these second messengers. Another mechanism of action includes processes of the hormones with intracellular receptors. This will selectively change transcription in the genes that it binds to, altering a phenotype change in the cell itself. The structure of these receptors contains factors allowing DNA bind. There are variations to the type of bond created, but the structure gives way for this change to take place.

These may seem like small tasks, however, each role is necessary for the endocrine system to function. As stated before, the endocrine system is the physiology of the endocrine glands. Each of these glands plays a major role in our bodies. The hypothalamus is a region in the brain that controls many of the body’s functions. One of the most important functions the hypothalamus has is actually linking the endocrine system to the nervous system, and does this with the aid of the pituitary gland, for which the hypothalamus helps to stimulate.

The hypothalamus controls many roles in the body such as hunger or body temperature. The pituitary gland helps the hypothalamus secrete hormones in the body for certain metabolic processes as well. The pituitary gland is a very small gland also located in the brain that secretes hormones that stimulate other endocrine glands. Feedback was a topic discussed earlier, and the pituitary gland helps to produce one of the only loops of positive feedback called oxytocin. Oxytocin is a peptide that is closely associated with the female reproduction.

It assists with labor, breast-feeding, and now related to certain other behaviors such as, including maternal bonding and behavior. The thyroid gland is one of the largest glands in the endocrine system. It is another gland that is controlled by the hypothalamus and the sub unit, the pituitary gland, and assists functions in the body including a role in metabolism (how fast the body burns energy). It produces hormones that use tyrosine and iodine to play the role in metabolism. The parathyroid is distinguished from the actual thyroid by a combination of two different types of cells.

The parathyroid controls amounts controls calcium in the bones, and is the only function that it is responsible for. This is important because the nervous system, the endocrine system, and the muscular system cannot properly function if calcium levels drop too low. If the calcium levels do drop too low, the parathyroid will excrete a hormone in the body to signal, thus aiding, for the creation of more to regulate the system. In addition, a hormone called calcitonin is a participant in calcium and phosphorus metabolism.

Similarly named with very similar functions, Clairol, or Vitamin D a steroid hormone, also contributes to regulating the body’s levels of calcium and phosphate. Vitamin D is not actually a vitamin, but a prohormone with two major forms, ergocalciferol and cholecaliferol. A further contributing gland in the endocrine system is the adrenal gland. This gland has a large number of coalitions in the body, whereas. The adrenal gland is respectively located atop the kidneys. The most notorious correlation with adrenal gland is to control stress.

It does this by response and synthesis of several different types of hormones and steroid hormones including adrenaline, cortical, and the previously discussed steroid hormone, corticoid (corticosteriod). When stress is introduced to the body the endocrine system begins sending messages throughout the body. The adrenal glands release information aiding in the ability to handle, abolish, or reduction of the stress that has been introduced. This is the gland I thank for helping me write this paper.

There are several other very necessary effects directed by the adrenal medulla that support contractions of the heart muscle, constriction of the blood vessels, assistance in pulmonary ventilation, including dilation of the eyes. There is another inclusion in the endocrine system called the pancreas. It’s an glandular organ located near the digestive system that produces several exclusive hormones including glucagon, somatostatin, digestive enzymes that are delivered to the small intestine, and highly needed insulin.

The pancreatic juice excreted by the pancreas is a remarkable agent in breaking down carbohydrates and proteins ingested by the body. Without the constant and normal production of insulin by the pancreas, there is a high probability of a low glucose level that can ultimately result in diabetes. Once diagnosed with diabetes this may lead to regular dosages of medicinal insulin. Glucagon has a major role in maintaining glucose at normal concentrations. Glucagon assists the liver in breaking down a molecule called glycogen which is stored by the liver when blood glucose levels are high.

It can be released later when levels fall. Somatostatin, GHIH, is a peptide hormone that endocrine system is managed by. This growth hormone inhibitor influences a process called neurotransmission and cell proliferation with its receptors. Two more closely related growth hormones named somatotropin and prolactin regulate, in unison with other cells or hormones, growth and metabolism. In addition to these endocrine glands, there are two more, the ovaries and testes. The ovaries are reproductive glands found almost exclusively in females.

They excrete progesterone and estrogen in the bloodstream. They function together at time to produce menstrual periods; however, estrogen alone can be released to stimulate certain effects including the appearance of breasts. The testes are a pair of male reproductive glands. They produce sperm and testosterone. Both are part of the endocrine system, and essential for the creation of new life. Without these two glands, and the hormones they produce, reproduction would not be possible; the continued existence of human would be in jeopardy.

Aside from all these glands, the nervous system, and other functional organs in the body, there are other hormones that make life possible after conception, after birth. I will outline a few of these for you. Antidiuretic hormone control and conserves body reducing the amount water by urination. When the hormone binds itself to the receptors on the cells inside the ducts that collect for the kidneys, it promotes absorption back into circulation increasing osmolarity, the measure of solute clarity, in urine while decreasing osmolarity of plasma.

Gastrointestinal hormones, referred to as the enteric endocrine system, are secreted into the blood to maintain and control proper functioning of the digestive system. Secretin stimulates the release of bile from the liver. It is released when information in the body has been sent to notify of low pH levels. It regulates this with the control of gastric acid. Gastric acid is released by another hormone, gastrin. It’s released by G cells in the stomach and pancreas. Ghrelin stimulates hunger, as well as many other vital roles including, lung development before birth, learning enhancement, and in fighting depression.

Motilin is a hormone that is known to be the housekeeper in the stomach. It stimulates removal of food in anticipation for the next round of nourishment. Cholecystokinin stimulates excretion of pancreatic enzymes that create digestion of proteins and fat. The gastric inhibitory polypeptide is found in the pancreas that inhibits gastric secretions and motility, or movement of a certain type of gradient, and is stimulated when the body receives information that the blood glucose is higher than normal.

The pineal gland is a small gland that produces a vital hormone called melatonin. Melatonin regulates proper sleeping habits. The pineal gland also has important biological associations with the reproductive states in animals. All of these tiny aspects are in our body make life possible. These are things we don’t generally think about as helping us the way they do. From the control of our stress, to having normal, natural sleeping habits, to amazing processes that are needed keep us alive, the endocrine system is absolutely amazing.

It’s a society of organs, hormones, cells, and molecules working together solely dedicated and designed for our survival. It works without end to create an inside harmony that we cannot see, but can depend on as long as we provide it with the right tools to function. We take these small steps for granted, not knowing the extent of our own bodies, not knowing the power it has. The endocrine system is a network that gives even the tiniest occupations great meaning for us all. It’s to be appreciated for all it gives, and all it does for the physiological processes in the human body.


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