HUMAN PHYSIOLOGY ANATOMY   ENDOCRINE SYSTEM

HUMAN PHYSIOLOGY ANATOMY   ENDOCRINE SYSTEM

BASIC THEORY

The endocrine system, in relation to the nervous system, controls and integrates bodily functions. These two systems work together to maintain body homeostasis. The functions of the two systems are interconnected with each other, but can be distinguished by certain characteristics. For example, the adrenal medulla and posterior pituitary gland that have neural origin. If both are destroyed or removed, then the function of the two glands is partly taken over by the nervous system.

When the endocrine system generally works through hormones, the nervous system works through neurotransmitters produced by nerve endings. The endocrine glands release their secretions directly into the blood. Endocrine glands include:

1. Langerhans Island in the pancreas,
2. Gonad (ovaries and testes),
3. Pituitary adrenal glands, thyroid and parathyroid, and thymus β.

Hormones and Their Functions

The word hormone comes from the Greek “hormone” which means to make a movement or arouse. Hormones regulate various processes that govern life.

1. Definition of the Endocrine System

The endocrine system is also called the appendix, which is a gland that does not have a special channel to remove its secretions. Secretions from the endocrine glands are called hormones. Hormones play an important role in regulating various activities in the human body, including reproductive growth, osmoregulation, digestion and integration and body coordination activities.

The endocrine system almost always works together with the nervous system, but the way it works in controlling body activity is different from the nervous system. There is

two different ways of working between the two systems. The two differences are as follows:

1. Compared to the nervous system, the endocrine system works more through chemical transmission.
2. The endocrine system pays attention to slower response times than the nervous system. In the nervous system, the action potential will work perfectly in just 1-5 milliseconds, but endocrine action through new hormones will be perfect in a very varied time, ranging from a few minutes to several hours. The adrenaline hormone works only for a short time, but growth hormone works for a very long time. Under the control of the endocrine system (using growth hormone), the growth process can take up to decades to achieve a perfect growth rate.

The basis of the endocrine system is hormones and glands (glands), as intermediate chemical compounds, hormones will provide information and instructions from one cell to another cell. Many different hormones enter the bloodstream, but each type of hormone works and affects only certain cells.

Figure 1. Endocrine glands and their location in the body

1. Endocrine Organ Compounding Cells

The cells making up endocrine organs can be divided into two, namely:

1. Neusecretory cells are cells that are shaped like nerve cells, but function as a hormone producer. Examples of neusecretory cells are nerve cells in the hypothalamus. These cells pay attention to endocrine function so that they can also be called neuroendocrine cells. In fact, all cells that can produce secretions are called secretory cells. Therefore, nerve cells like those in the hypothalamus are called neusecretory cells.
2. True endocrine cells are also called class endocrine cells, namely endocrine cells that actually function as hormone-producing, do not have the shape of nerve cells. The true endocrine glands release the hormones they produce directly into the blood (bodily fluids).

1. Classification, Function and Nature of Hormones

Based on its chemical nature, hormones can be classified into three, namely peptide and protein hormones, steroids, and tyrosine derivatives.

Steroids

Peptide

Large Protein Derivative Tyrosine

Estrogen Testosterone Progesterone Corticosteroid Vitamin D-3 Hormones Hypothalamus Angiotensin Somatostatin Gastrin Secretin Glucagon Calcitonin Insulin

Prolactin Growth Hormone Parathormone

LH FSH TSH Catecholamines, including: Noradrenaline Adrenaline Thyroid Hormones, including: Thyroxine (T4) Triiodotironin (T3)

In addition to the various hormones mentioned above, there are a number of chemical-like hormones, including:

1. Thymic hormone, a hormone from the thymus gland (thymus), plays a role in influencing the development of B lymphocyte cells into plasma cells, which are antibody-producing cells.

2. Brakidin hormone is a hormone produced by glands that are actively working as vasodilators (which cause blood vessels to dilate) so that it can increase blood flow and stimulate spending in sweat and saliva in greater amounts.
3. Erythropuitin hormone is a glycoprotein whose synthesis process involves the liver and kidneys, this hormone can stimulate the formation of blood sal in the bone marrow so that the body will produce red blood cells in greater numbers. This is beneficial in increasing the amount of oxygen that can be transported by the blood.
4. The hormones Prostaglin, Erythropuitin, Histamine, Kinin, and Renin can be widely synthesized by various tissues or organs that actually do not function as endocrine organs.
5. Pheromone hormone is a specific chemical compound released by the body into the environment and can cause behavioral, developmental, reproductive responses. To provide sexual attraction, mark territory, recognize other individuals in the same species and play an important role in synchronizing the sexual cycle.

1. Types of Endocrine Glands

1. Pituitary

The cerebral pituitary or dance gland is a small oval structure attached to the lower surface of the brain through the infundibulum. Its location is very well protected, which is located in the cicaossis sphenoidalis cell. It is called the master endocrine gland because the hormones produced by this gland affect many other endocrine glands.

This gland is located in between tursica, spenoidalis casos sphere base crania. Oval shaped with a diameter of about 1 cm and divided into two anterior lobes of the lobe, is the largest part of the pituitary about 2/3 of the pituitary at the base of the cerebrum and produces various hormones that regulate the activities of other glands. Therefore, the pituitary gland is called the master gland.

The pituitary gland is divided into three parts, namely the anterior, middle, and posterior parts.

1. The anterior pituitary, the hormone produced by the anterior pituitary gland, consists of:

• Somatotropin hormone (for cell division, growth)
• Thyrotropin hormone (thyroxine hormone synthesis and iodine uptake)
• Adrenocorticotropin hormone stimulates the cortex glands to form hormones)
• Lactogenic Hormone (ASI secretion)

1. Pituitary center

The middle pituitary produces melanocyte-stimulating hormone or Melanocyte Stimulating Hormone (MSH). If this hormone is produced, it causes the skin to become black.

1. Posterior pituitary:

• The hormone oxytocin (stimulates birth contractions).
• Vasopressin hormone (stimulates kidney water reabsorption).

The function of the posterior pituitary (adenohipofise), consisting of Anti-diuretic Hormone (ADH): regulates the amount of water that passes through the kidneys, reabsorbs water and controls blood pressure in arterioles.

• Oxytocin hormone: regulates uterine contractions during childbirth and breastfeeding during breastfeeding.

The pituitary is a gland the size of a pea, which is located in a reinforced structure (interrupted tursica) at the base of the brain. interrupted tursica protects the pituitary but provides very little room to expand if the pituitary enlarges and will tend to push upward, often pressing areas of the brain that carry signals from the eye and may cause headaches or vision problems.

The pituitary controls the function of most other endocrine glands. The pituitary is controlled by the hypothalamus, which is the part of the brain that is located just above the pituitary. The pituitary has 2 different parts, namely the anterior lobe

(front) and posterior lobes (back).

Figure 2. Hypothalamus and pituitary gland

1. Thyroid gland

Located and attached to the trachea at the front. The thyroid gland is one of the largest endocrine glands in the human body. This gland can be found in the neck. This gland serves to regulate the body’s speed of burning energy, making protein and regulating the body’s sensitivity to other hormones. The thyroid gland can be stimulated and become bigger by epoprostenol. Thyroid function is regulated by the pituitary thyroid stimulating hormone (TSH),

under the control of the hypothalamic releasing hormone (TRH) hypothalamus through the hypothalamic pituitary feedback system. The main factors affecting the rate of TRH and TSH secretion are circulating thyroid hormone levels and the body’s metabolic rate.

Figure 3. Anatomy and histology of the thyroid gland.

2. Parathyroid gland

This gland is located on each side of the thyroid gland in the neck. This gland consists of 4 pieces arranged in pairs which produce the hormone parathyroxine. There are 2 types of cells in the parathyroid gland, there are main cells that secrete parathyroid hormone (PTH) which functions as a controller of calcium and phosphate balance in the body through increasing blood calcium levels and decreasing blood phosphate levels and oxidative cells which are the stages of chief cell development.

3. Adrenal

This gland is shaped like a ball, which attaches to the upper part of the kidney. This gland is also called the adrenal gland or supra renal gland. The adrenal gland can be divided into two parts, namely the outer part of which is yellowish named the cortex, producing the hormone cortisol and the middle part (medulla), the adrenal hormone (epinephrine) and nor-adrenaline (norepinephrine)

All types of stress include emotions and physical trauma triggers the hypothalamus to stimulate the adrenal glands.

Figure 5. Adrenal glands. Both the medulla and adrenal cortex are under the control of the hypothalamus when they help us respond to stress

1. Pancreas

The pancreas is located behind the stomach in front of the lumbar vertebra I and ll which are composed of langerhans islands scattered throughout the pancreas. On this island of Langerhans there are alpha cells and beta cells. Alpha cells produce glucagon while beta cells produce the hormone insulin. The hormone insulin controls the concentration of glucose in the blood. Excess glucose will be carried to the liver cells and will then be remodeled into glycogen to be stored. Lack of this hormone will cause diabetes.

Figure 6. Anatomy of the Pancreas

2. Thymus Gland

Located in the midiastinum behind the sternum bone, the thymus gland is found in children under the age of 18 years. This gland is located in the thorax about as high as a tracheal branching, reddish in color and consists of 2 lobes. In newborns it weighs about 10 grams, and its size increases in adolescence around 30-40 grams.

The thymus gland produces an immune cell that helps in the defense of the body, besides the thymus gland hormone plays a role in helping body growth.

Figure 7. Anatomy of the thymus gland

3. Sex hormones
4. Testicles

Testes are in men, located in the scortum. In the testes there are leydig cells that will produce the hormone testosterone. The testosterone hormone will determine the nature of virility, for example the presence of a beard, mustache, Adam’s apple, etc., and produce sperm cells (spermatozoid).

1. Ovarika

Ovarian glands are found in women, are located in the ovaries on the left and right of the uterus and produce the hormones estrogen and progesterone (corpus luteum). This hormone can affect the work of the uterus and provide female characteristics, such as large pelvis and narrow shoulders.

No. Endocrine glands produced by Horimoni type

1

Pituitary gland / pituitary 1. Growth hormone (somatotropin)

2. Thyroid-stimulating hormone (TSH)
3. Adrenocorticotropin (ACTH) (anterior lobe)
4. Follicle-Stimulating Hormone (FSH)
5. Luteinizing hormone (LH)
6. Prolactin
7. Pituitary gland 1. Antidiuretic (vasopressin)
8. Oxytocin Globus posterior)
9. Thyroid gland 1. Thyroxine
10. Calcitonin
11. Parathyroid gland Parathyroid hormone (parathormone)

5

Adrenal glands 1. Mineralocorticoid cortex, glucocorticoids and sex hormones

2. Medulla epinephrine and norepinephrine

6

Pancreatic gland 1. Insulin

2. Glucagon
3. Somatostatin
4. Ovaries 1. Estrogen
5. Progesterone
6. Testes Testosterone

1. Hormone Properties

All hormones generally show the same nature.

Some of the common characteristics exhibited by hormones are as follows:

1. Hormone Polypeptides are usually synthesized in the form of inactive precursors (called prohormones), for example proinsulin. Prohormone has a longer chain than its active form.
2. Some hormones can function in very low concentrations and some hormones are short-lived.
3. Some hormones (such as adrenaline) can react immediately with target cells within a few seconds, while other hormones (for example estrogen and thyroxine) react slowly in a few hours to several days.

4. In the target cell, the hormone will be related to the receptor.
5. Hormones sometimes need a second messenger in the mechanism.

1. Mechanisms of Hormone Action
2. Hormone Receptors

The membrane receptors for hormones in a cell can be located on the membrane or cytoplasm which are usually receptors for protein hormones or bind to their receptors and form receptor hormone complexes. Hormone-receptor formation occurs through a mechanism similar to the combination of a key and a lock. The receptor hormone complex will trigger a series of biochemical reactions that give rise to biological responses.

Here are examples of some of the events that hormones can change by working as above:

1. Changes in enzyme activity, namely changes in enzyme activity allow certain metabolic processes to be held or stopped.
2. Activating the active transport mechanism The active transport process is very important for cells to enter or remove a substance.
3. Microtubule formation activity: changes in the activity of microtubule formation can affect various events that depend on it, including amoeba movement and cell mitosis.
4. Changing the activity of DNA metabolism Changing the activity of DNA metabolism can affect the process of growth or cell division.

2. Hormone Receptors in Cytoplasm (Cytosolic Receptors)

Hormones found in the cytoplasm of target cells. Hormones that use cytosolic receptors are steroid hormones and amino acid-derived hormones. This hormone is very soluble in lipids so that it easily passes through the target cell membrane. During the circulation of blood throughout the body. The hormone will be released from the carrier molecule and enter the target cell.

In the target cell cytoplasm, hormones combine with special receptors to produce active receptor hormone complexes. The complex has a very high joining ability to DNA so that after entering the nucleus, it will immediately combine with DNA. This is what started the DNA transcript. The binding of the receptor hormone complex to the promoter area will stimulate certain genes to be active or passive.

1. Endocrine system physiology
2. Produces hormones that are flowed into the blood needed by certain body tissues.
3. Control the activity of the body’s glands.
4. Stimulate the activity of the body’s glands.
5. Stimulate tissue growth.
6. Regulates metabolism, oxidation, increases absorbsglukossa in the small intestine.
7. Affects the metabolism of fat, protein, carbohydrate, vitamins, minerals and water.

WORKSHEET

1. What is an endocrine system?

2. Mention and explain the cells making up the endocrine organs!

3. State and explain the types of endocrine glands!

4. Name the hormones produced by the endocrine system!

5. Mention and explain the mechanism of action of hormones!

6. Mention the physiology of the endocrine system!