The Essay On Nervous And Endocrine Systems Explores Homeostatic Mechanisms.

Nervous and Endocrine systems, and Homeostatic mechanisms 

As a biology teacher, you have been requested to produce good teaching resources for a new academic year.

The contents should be well-researched and include appropriate illustrations where necessary to support written text. Accuracy, clarity and neatness of work are equally very crucial.  

A completion of the following set of tasks would therefore provide some relevant material that will be used in the teaching resources bank:

• Describe the organisation of the endocrine system, using appropriate diagrammatic illustration to support text content.

• Use three specific examplesof hormonal changes in the human body to describe how the endocrine system functions to bring about those changes in the body.  

Give a clearly detailed description of three homeostatic systems, showing how each of them works. Appropriate pictorial illustrations should be included. Details should show your understanding that they are regulatory systems essential for maintaining a steady state in the body.

Write a detailed explanation of how the interrelationship between structures in the endocrine system and their related hormones work together in the body of an individual facing a panic, stressful situation. Use annotated flow diagrams to support your write-up.

Using annotated diagrams, write a detailed explanation of two examples of Positive homeostatic feedback and two examples of Negative homeostatic feedback respectively.

Produce a detailed account of how the nervous and endocrine systems interact with each other. You should also briefly explain your understanding of the consequences of malfunction in each system.  

Describe possible homeostatic malfunctions and what these do to the body.

Consider all of the internal regulatory mechanisms, including blood glucose control, temperature and water regulation. Explain how malfunctions lead to disorders in a clear, logical manner. You ought to show a clear understanding of the effects of the disorders and how they are rectified.  (You do not need to give detailed descriptions of treatment.)  

Organization and Function of the Endocrine System

The endocrine system consists of glands that secrete and produce hormones used to regulate organs and cells activities in the body (Brandman & Meyer, 2017). These activities include growth, tissues functions, reproduction, sleep, sexual function, metabolism and moods among other things. The nervous system on the other hand, is the part of the body that coordinates its actions by transmitting signals to and from different parts. The nervous system detects changes in the environment that causes impacts on the body, then works together with the endocrine system to respond to the impacts. The nervous system involves two main parts which are the peripheral and the central nervous systems. According to Charkoudian (2013), the CNS is composed of the spinal cord plus brain while the PNS is made up of nerves.

Davis (2016) states that the endocrine system involves organs that make and secrete chemical substances and hormones that regulate cells and organs activities. The body is made up of many parts which produce hormones but there are main glands that make up the endocrine system and they include thyroid, hypothalamus, pituitary, adrenals, parathyroid, pineal body, testes and ovaries.

1. Thyroid gland

Thyroid gland is found in the front neck under the muscle and skin layers. The thyroid gland is butterfly shaped with two wings which wrap about the trachea (Macfarlane, 2015). The main purpose of the thyroid is to produce thyroid hormones which are tyrosine-based hormones basically involved in the regulation of metabolism. The hormones are, the T3 and T4 and are partially made of iodine. Lack of iodine leads to a decrease in the manufacture of the T3 and T4, enlarges the thyroid tissue and causes goitre.

2. Hypothalamus gland

Hypothalamus gland is found deep inside the brain and it controls the pituitary gland and also produces releasing and inhibiting hormones. Together, pituitary and hypothalamus communicate to the other endocrine glands in the body to release the hormones that defend and affect every aspect of one’s health. Hypothalamus gland hormones include the anti-diuretic, oxytocin corticotropin-releasing, and gonadotropin- releasing, growth-releasing, somatostatin and the thyrotropin-releasing hormones. Corticotropin-releasing hormone leads the body respond to emotional and physical stress, suppresses appetite and stimulates anxiety. Anti-diuretic hormone regulates the levels of water in the body and affects blood volume and pressure (Marieb & Hoehn, 2015)

3. Adrenals glands

Also referred to as suprarenal glands and produces a number of hormones including adrenaline and steroids aldosterone. These glands are located above the kidneys and release hormones into the bloodstream. Meier and Gressner (2014) states that, the adrenal glands includes two parts namely the adrenal cortex and the medulla. The hormones produced by adrenal glands are Mineralocorticoids which aids to reserve the body’s water and salt level which then regulate blood pressure, the glucocorticoids that helps to regulate metabolism and is involved in the reaction to illness, the adrenal androgens namely testosterone and dehydroepiandrosterone which play a role in early growth of the male sex organs in childhood and lastly the catecholamines produced by the medulla. The catecholamines are involved in all the physical characteristics of the fight or flight reactions.  

Mechanisms of the Homeostatic Systems

Homeostasis is the procedure by which biological systems self-regulate to sustain stability as they adjust to ideal conditions for survival.  These homeostatic mechanisms maintain a constant internal environment regardless of changes in the external environment by giving the cells what they require for survival (nutrients, oxygen, and removal of waste). This is essential for the well-being of the entire body and individual cells.

There are three interdependent components that aid in the homeostatic regulation. They are the receptor, integrating centre and the effector. The receptor senses changes in the environment then passes the information to the integrating centre where it is processed, then the effector responds to the commands from the integrating centre by either enhancing or opposing the stimulus.

The interrelation between structures in the endocrine system and their linked hormones and how they work together in the body of a person facing a panic, stressful situation

There is a complex interrelation between endocrine system glands and related hormones. Stress is the body’s way of responding to any kind of threat or demand. Panic is an unanticipated sensation of fear which is very strong and prevents logical thinking and reasoning. Panic replaces logical thinking and reasoning with overwhelming feelings of anxiety. The body responds when it senses danger whether real or imagined in an automatic process known as the fight or flight reaction. To achieve this reaction (flight or fight), the hypothalamus initiates two systems: the sympathetic nervous and adrenal-cortical systems. The adrenal-cortical system cause reactions in the body using the blood circulation while the sympathetic nervous system use the nerve trails. Each time the body senses danger, it automatically tries to protect itself. There are three hormones released during the fight or flight response which are Cortisol, Adrenaline and Norepinephrine. Adrenal glands release adrenaline and norepinephrine hormones which give the body a sudden rush of energy. This happens after the sympathetic nervous system sends out stimulus to the adrenal medulla. The release of these stress hormones brings several changes in the body. These changes include an increase in blood pressure and heart rate. The pupils are also affected during this response causing them to dilate.

There are control centres in humans basically found in the brain and other parts of the body. These centres are used to monitor conditions like pressure, temperature, and tissue and blood chemistry. There are two types of homeostatic feedbacks namely positive and negative feedbacks.

Positive feedback encourages and intensifies changes in the physiological condition of the body. This encouragement drives the change farther out of the normal range. Provided there is a definite endpoint, this type of feedback is normal for the body. Examples of positive feedback include blood clotting and childbirth.

Blood clotting is a good example of positive feedback in the body. When there is damage in the outside and inside of the body, the damaged tissues tend to release factors that cause platelets to adhere to the tissue at the location of the injury. The platelets produce granules that initiate and attract more platelets and cause them to cohere to each other. Fibrinogen is then converted to fibrin creating a meshwork that traps platelets and blood cells, forming a clot and stopping the bleeding (Niswander et al., 2014). Thrombin binds to thrombomodulin activating protein C which prevents the coagulation cycle hence stopping the cascade. Step one of the clotting process is the activation of the enzyme prothrombin into its active form thrombin. However, what makes it a positive feedback is the fact that thrombin can also activate the coagulation components that precede in the cascade.

Interrelationship between Structures in the Endocrine System and their Linked Hormones

When labor starts, it is essential that the process proceed quickly or the life of the baby and mother will be at risk. The cascade of muscular events involved in labor and delivery are the results of a positive feedback system designed to do this. The inducement for the process to start is the first contraction of labor. As the baby is pushed towards the cervix by powerful contractions of the uterus, stretch detectors in the uterus monitor how much the cervix stretches. Pituitary glands in the brains receive messages from the sensors hence releasing oxytocin hormone into the bloodstream of the mother. This hormone oxytocin acts on the effectors causing stronger contractions making the baby move farther down the birth canal. The continuous cycle of releasing oxytocin and stretching ends when the baby is out.

The negative feedback reverse or resist the process of change when conditions get out of normal range. Examples of negative feedback include blood sugar regulation and thermoregulation. Some effects of this feedback (negative feedback) are, reducing the overall gain of a system and with the degree of reduction being reduced to the system open-loop gain, reducing noise, distortion and sensitivity to external changes.

During temperature fluctuations, the hypothalamus reacts to the changes accordingly. When it is too cold the body trembles to raise the temperatures and when it’s too hot the body sweats to cool the temperatures due to evaporation. 

Insulin and glucagon are the hormones involved in regulating blood sugar levels. Insulin is used by the body to keep blood sugar level from getting too high or too low. When the sugar level in the blood rises, insulin hints signals to muscles, liver and other cells to store the excess glucose. The excess sugar is stored glycogen in the muscles and liver and some as body fat (Prall, 2017).

Conclusion

Human bodies need to be in a stable condition to perform their roles effectively. Stability of the internal environment is maintained regardless of the changes in the outer environment through a process known as homeostasis. There are two systems involved in controlling and coordinating many functions to keep the body working in balance. The systems are the nervous and endocrine systems. The nervous systems use electrical impulses while endocrine systems use hormones.

References

Brandman, O., & Meyer, T. (2017). Feedback loops shape cellular signals in space and time. Science, 322(5900), 390-395.

Charkoudian, N. (2013, May). Skin blood flow in adult human thermoregulation: how it works, when it does not, and why. In Mayo clinic proceedings (Vol. 78, No. 5, pp. 603-612). Elsevier.

Davis, J. D. (2016). Homeostasis, feedback and motivation. Analysis of motivational processes, 23-37.

Macfarlane, R. G. (2015). An enzyme cascade in the blood clotting mechanism, and its function as a biochemical amplifier. Nature, 202(4931), 498.

Marieb, E. N., & Hoehn, K. (2015). Human anatomy & physiology. Pearson Education.

Meier, U., & Gressner, A. M. (2014). Endocrine regulation of energy metabolism: review of pathobiochemical and clinical chemical aspects of leptin, ghrelin, adiponectin, and resistin. Clinical chemistry, 50(9), 1511-1525.

Niswander, L., Jeffrey, S., Martin, G. R., & Tickle, C. (2014). A positive feedback loop coordinates growth and patterning in the vertebrate limb. Nature, 371(6498), 609.

Prall, O. W., Menon, M. K., Solloway, M. J., Watanabe, Y., Zaffran, S., Bajolle, F., ... & Stennard, F. A. (2017). An Nkx2-5/Bmp2/Smad1 negative feedback loop controls heart progenitor specification and proliferation. Cell, 128(5), 947-959.