Nervous and Endocrine systems, and Homeostatic Mechanisms

This article discusses the nervous and endocrine systems, the organization and function of the endocrine system, mechanisms of the homeostatic systems, and the interrelation between structures in the endocrine system and their linked hormones. It also explains how homeostasis is achieved by controlling blood sugar levels.

Running head: NERVOUS & ENDOCRINE SYSTEMS 1
Nervous and Endocrine systems, and Homeostatic Mechanisms.
Student’s Name
University Affiliate

NERVOUS &ENDOCRINE SYSTEMS 2
Introduction
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.
Organization and Function of the Endocrine System
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.

NERVOUS &ENDOCRINE SYSTEMS 3
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.

NERVOUS &ENDOCRINE SYSTEMS 4
Diagram of the endocrine system
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

NERVOUS &ENDOCRINE SYSTEMS 5
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.

NERVOUS &ENDOCRINE SYSTEMS 6
The following diagram shows the interrelationship endocrine system structures and hormones
involved
Homeostatic feedback
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
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
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

NERVOUS &ENDOCRINE SYSTEMS 7
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.
Childbirth
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.

NERVOUS &ENDOCRINE SYSTEMS 8
Negative feedback
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.
Thermoregulation
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.
Blood sugar regulation
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).
An example of how homeostasis is achieved by controlling blood sugar levels.

NERVOUS &ENDOCRINE SYSTEMS 9
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.

NERVOUS &ENDOCRINE SYSTEMS
10
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.