Detailed Biology Report: Endocrine System and Homeostasis

This report delves into the complexities of the endocrine system, exploring the major endocrine glands such as the pituitary, thyroid, and adrenal glands, and the hormones they produce. It examines the functions of key hormones, including growth hormone, thyroxine, insulin, and testosterone, and their roles in regulating various bodily functions. The report also elucidates the bloodstream's role in hormone distribution and details the molecular processes of steroid and peptide hormone action, highlighting the differences in their mechanisms. Furthermore, it discusses the principles of homeostasis, feedback mechanisms, and the need for specificity in hormone action, providing a comprehensive understanding of the endocrine system's critical role in maintaining internal stability and regulating physiological processes. The report covers the core principles of homeostasis and various feedback mechanisms, such as blood sugar control.

Running head: BIOLOGY
BIOLOGY
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Introduction:
The endocrine system is defined as the chemical messenger system encompassing
feedback loops of hormones which are released by the internal glands of an organism to act on
the cells. The effects of the hormones of the endocrine system are dependent on the program
responses of the cells that are targeted (Bouillon et al. 2015). Some may cause short term effects
such as elevation of the heart rate and some have long term effects like increase of height. This
paper will discuss the different part of the endocrine system in following paragraphs.
Discussion:
1.1 main endocrine glands and describe the hormones that are produced by them:
While the significant number of body organs make hormones, major glands which
together produce endocrine involve pituitary, thyroid, parathyroid, adrenals, pancreas, and ovary
for females and testis for male (Melmed et al. 2015). Out of all endocrine glands that are part of
the endocrine system, pancreas is part of both systems such as the digestive and endocrine
system. The prime reason behind this is that it secretes hormones into the bloodstream for
targeting specific organs and secretes enzymes in the digestive system for proper digestion of the
organ.
The pituitary gland secretes hormones such as growth hormone, prolactin, corticotrophin,
antidiuretic, and oxytocin. Thyroid gland secretes hormones such as thyroxine, triiodothyronine.
The parathyroid gland secretes hormones such as calcitonin and parathormone. The adrenal
gland secretes hormones corticosteroids, catecholamines epinephrine, norepinephrine, and
androgens. Pancreas gland secretes hormones such as Somatostatin, insulin, secretin, glucagon,

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gastrin, amylin, gastrointestinal hormones, and pancreatic polypeptides (Sherwood, L. 2015).
The ovarian gland secrets the estrogen, progesterone and testis gland secrets testosterones
(Sherwood, L. 2015) ( appendix 1).
1.2. Explain the function of the major hormones of the endocrine system
As discussed above, there are seven major glands which secrete the hormones which
regulate the normal function of the body.
Considering the pituitary gland, growth hormone I which stimulates the growth of body
tissues and bone and provide minerals. Prolactin stimulates milk production for breastfeeding
babies. Thyrotropin is used for stimulating thyroid glands for making thyroid hormones.
Corticotrophin is used for stimulating the adrenal gland and the antidiuretic regulates the water
balance by controlling the functions of the kidney (Ahmed 2018). Oxytocin triggers the
contraction of hormones. Considering the thyroid gland, thyroxin controls and triggers an active
form of triiodothyronine (Www.innerbody.com 2019). Triiodothyronine, on the other hand,
controls almost the majority of the function of the body. It also controls the rate at which cells
burn fuels from food to make energy. Considering parathyroid hormones, calcitonin and
parathormone both stimulate the growth of the bone by stimulating the use of calcium and
phosphorus (Nicolaides, et al. 2015). Considering adrenal glands, corticoids increase the
gluconeogenesis, retain sodium, excrete potassium and stimulates secondary sex traits.
Epinephrine and norepinephrine increases the heart rate, muscle contraction, glycolysis, and
vasoconstrictions. Considering the pancreas glands, somatostatin is considered as growth
hormone inhibiting hormones which regulate and affects neurotransmission. Insulin controls the
anabolism, of the body by degrading the carbohydrate present in the bloodstream. Secretin is the
hormone which stimulates the secretion of the liver as well as pancreas (Hutchinson, Burholt and

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Hamley 2017). Glucagon controls the catabolism by participating in the process of making
carbohydrate when the body requires it the most. Gastrin is a peptide hormone which stimulates
the secretion of the gastric acid by regulating parietal cells and it assists in gastric motility.
Amylin is the hormone which is used controlling the function of glucagon, delays gastric
emptying (Hay et al. 2015). Gastrointestinal hormones regulate the gut mucosal growth for
facilitating the function of the digestive system. Pancreatic polypeptides regulate the function of
the pancreatic secretion activities. Considering ovarian glands and mammy glands, progesterone
and estrogen facilitate female development, maintain pregnancy, implant an egg in the uterus
and development of mammary gland (Berryhill, Trott and Hovey, 2016).Considering hormones
of testis gland, testosterone facilitates male growth and sexual activities in male (Jung et al.
2018)
1.3: bloodstream’s role in the distribution of hormones to target organs:
There are different kinds of hormone such as water-soluble hormones and lipid soluble
hormones traveling through the bloodstream to work on the targeted organ and regulate the
associated function of the targeted organ. Water soluble hormones travel in the blood dissolved
in the plasma (Melmed et al. 2019). The plasma diffuses from the capillaries into tissue fluids
which further travels to target cells. The lipid soluble hormones such as steroid and thyroid
hormone bind to the plasma proteins by traveling through the blood. By binding to the plasma
protein they travel to the targeted cells (Melmed et al. 2019). Majority of the lipid soluble
hormones are bound to the plasma protein of blood, only very few amount of hormones are
freely traveling in the blood. They are highly hydrophobic in nature and hence they are bound to
plasma protein to avoid the contact of water. It is a crucial factor to note that majority of the lipid
soluble proteins are inactive in nature and partially water-soluble which enable them to travel

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more easily to the targeted cells with the help of blood as potential transporter (Boron and
Boulpaep 2016)
3.1: the two molecular processes in steroid and peptide action:
Peptide hormones are secreted and function in an endocrine manner to regulate many
physiological functions such as growth, metabolism, cardiac function stress and reproductive
physiology (Hutchinson, Burholt and Hamley 2017). They are not fat soluble and hence they are
not able to enter the cell membrane as the cell membrane contains the fatty components. It will
inhibit the normal function of the peptide hormones (Www.ivyroses.com, 2019). Consequently,
the inactive form of the hormone bind to the receptor protein on the surface of the targeted cells.
While they bonded to the receptor protein, they convert themselves to the active form and
activate the receptors by triggering. Secondary messenger molecule trigger the internal cellular
response such as uptake and secretion of, molecules (Sewald, N.,and Jakubke, H. D. 2015).
Effect of the receptor activation is that due to involvement in cascade, amplification processes it
enhances normal metabolic function such as facilitate the responses of adrenalin. For example,
insulin attached to the insulin receptor and passes its messages into the target cells (Meijer et al.
2016). Consequently, it affects the glucose uptake of the muscles and adipose cells, inhibiting the
sudden rising of the blood glucose level.
On the other hand, the steroid hormones are hydrophobic in nature and only lipid
soluble. Therefore, they pass through the cell membrane of the target cell with the help of
diffusion. In order to be active and transport to the target cells, they bind to the receptor proteins
present in either cytoplasm or nucleus male (Boron and Boulpaep 2016. ). Mostly these steroid
hormones bind with the receptors located at the cytoplasm of the cell. After attachment, the
receptor, as well as the hormone, become activated. After binding they travel to the nucleus and

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bind with other specific receptors of the nucleus. After activation and attachment, they regulate
the production of certain proteins through the stimulation of transcription genes which in turn
acts transcription factors male (Boron and Boulpaep 2016) . However, the responses of the cells
because of receptor activation may vary since these hormones trigger the gene activity inside the
cells which controls the particular cells (Boron and Boulpaep 2016). As they act by triggering
the gene activity, the responses are usually slower than peptide hormones.
In both cases, if the receptors are blocked that more hormones are required to add for the
increasing the competition and remove the blockage. Testosterone is transported into the
cytoplasm and attached to the androgen receptor and after activation, they stimulate the sexual
functions and the traits of masculinity (Sherwood, L. 2015).
Outline the need for specificity and relate this to the action:
The specificity of receptor and variation of it depends on their crucial factors such as the
level of hormone in the blood, the numbers of hormone receptors present on the target cells and
the hormone receptor affinity (Melmed et al. 2019). Considering the first factor, the amount of
hormones secreted by the specific gland is regulated by a feedback mechanism (Melmed et al.
2019). Considering the second factor, the number of the receptors are present in the target cells
whether they are blocked or not. Considering the third factor, the specificity of the receptor is
dependent on the sensitivity of the receptor since the targeted cells can alter the sensitivity. For
example, receptors that attached with the peptide hormones tend to find on the plasma membrane
of the cells (cell surface receptors) as they do not enter into the target cells (Www.ivyroses.com,
2019). They work by the bind to the external receptors and works through secondary messengers
which affect the pre-existing proteins within the cells. On the other hand, steroid hormones
receptors and associated receptors are generally soluble proteins which act on the cells by acting

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on the genes of the cells. Hence, the receptors for the steroid hormones are required to be
intracellular receptors present in either cytoplasm or nucleus (Sewald and Jakubke 2015)..
3.3: different mechanisms for fat-soluble and non-fat soluble hormones:
The non-fat soluble hormones are hydrophilic in nature and regulate the growth and
other physiological functions of the body. Hence, the mechanism of action is different from the
fat-soluble hormones which are hydrophobic in nature and. Receptors that attached with the
peptide hormones tend to found on the plasma membrane of the cells (cell surface receptors)
(Www.ivyroses.com, 2019). The works by the bind to the external receptors and works through
secondary messengers. On the other hand, steroid hormones regulate the metabolism and hence
it works by attaching the working on a genetic level.
Conclusion:
Endocrine systems are the system where chemical system messengers or hormones are
secreted and enter directly into the circulatory system in order to regulate different functions of
the targeted organs. Bloodstream plays a huge role in the transportation of water-soluble
hormones such as peptide hormones. Depending on the nature of the hormones, the receptors
and functions are regulated.
2. Introduction:
In biology, homeostasis is the state of steady internal physical as well as chemical
condition maintained by the body to work properly (Park and Ahima 2015). It is a tendency of
the body towards maintaining a relatively stable equilibrium (Park and Ahima 2015). The
following section will elaborate on the principle of homeostasis and process controlled by a
feedback mechanism.

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2.1: core principles of homeostasis of the body:
Homeostasis is defined as the way the body maintains a stable internal environment for
regulating the proper function of the body. The hemostasis regulations involve the receptors,
control centre and the effectors (Park and Ahima 2015). The receptor receives information
regarding the changes in the environment. The control centre receives the information regarding
the changes in the environment. The effector works in response to the stimuli. The core principle
of homeostasis is to maintain stability by maintaining the body's temperature (Hall 2015). The
increase in temperature will affect the activity of the hormones. The second principle is to
maintain the stability or equilibrium by regulating the amount of water present in the body. The
changes in the water level affect the normal function of the body such as metabolism,
physiological changes, and osmosis (Hall 2015). The increase in water level may affect the
metabolism of the body as while working the enzymes (protein molecules) displaced the water
molecules. Hence, it will affect the normal function of the body. The third principle is to
maintain the homeostasis of the body by regulating the amount of glucose in the body, especially
in the bloodstream. The high glucose level of the body affects the osmosis and rate of respiration
and hence it is crucial to maintain the homeostasis of the body (Park and Ahima 2015). The last
principle of the homeostasis is to maintain the internal stability or equilibrium of the body by
maintaining a proper amount of nitrogenous waste in the body. Hence, it is crucial to detoxify
the nitrogenous waste from the body for restoring the normal function of the body.
Process controlled by a feedback mechanism such as blood sugar control:
Blood glucose levels are regulated within limited parameters. The primary sensors for
this process are beta cells presented in pancreatic islets. These cells provide responses because
of a rise in the sugar level of the body by secreting the insulin and it simultaneously inhibit the

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alpha cells from secreting glucagon (Park and Ahima 2015). The combined level of these two
hormones acts on the specific tissues of muscles, livers, and adipose for maintaining the glucose
level of the body.
Positive feedback mechanism:
. It is a process human body recognizes or senses any change and further activates and
acts on amplification of certain effects which will accelerate the changes in the body (Hall,
2015). While glucose level of the blood is low in the bloodstream, the signal is transferred to the
hypothalamus and stimulate the function of the hypothalamus. After activation or stimulation, it
provides the signals to the anterior pituitary of the pancreas for releasing the hormone for
controlling the level of blood glucose. Anterior pituitary further controls the secretion of insulin
by reducing the secretion of insulin, a hormone which facilitates the degradation of carbohydrate
(Melmed et al. 2019). As discussed above while the level of carbohydrate degrading hormone
decreased, it further triggers the secretion of glucagon, the hormone that facilitates the formation
of the carbohydrate (Melmed et al. 2019). Consequently, it increases the level of blood glucose
in the blood (appendix 2).
Negative feedback:
While glucose level of the blood increase in the bloodstream, the signal is transferred to
the hypothalamus and stimulates the function of the hypothalamus (Everly and Lating 2019).
After activation or stimulation, it provides the signals to the anterior pituitary for releasing the
hormone of the pancreas in order to control the level of blood glucose. Anterior pituitary further
controls the secretion of glucagon by reducing the secretion of glucagon, a hormone facilitates
the formation of the carbohydrate (Everly and Lating 2019). As discussed above while the level

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of carbohydrate forming hormone decreased, it further triggers the secretion of insulin, the
hormone that degrades the carbohydrate. Consequently, it decreases the level of blood glucose in
the blood (appendix 2).
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Conclusion:
Thus it can be concluded that homeostasis is the state of steady internal physical as well
as chemical condition maintained by the body to work properly. There are four core regulations
such as blood glucose, water balance, temperature and nitrogenous wastes. These functions are
regulated by positive and negative feedback to maintain homeostasis.
Task 3:
Hormone replacement therapy:
Hormone replacement therapy can refer to any form of hormone therapy for medical
treatment but often researchers use the term to refer to menopausal HRT. The benefit of
hormone replacement therapy is that it protects against both coronary heart disease and stroke,
restoring the wellbeing. Other benefits of the hormone replacement therapy include relief from
the menopausal symptoms, prevention of osteoporosis and maintaining the quality of life in
menopausal years (Lobo 2017).
Medical use of synthetic hormones:
In the clinical, HRT acts supplement a lack of a naturally occurring hormone such as
estrogen during menopause or androgen replacement therapy in order to support the wellbeing of
men with testicular dysfunctions, cancer or any other severe diseases (Lobo 2017). On the

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other hand, some of the hormones are given as substitution of other hormones associated with
gender. For example, testosterone is given to Trans men and estrogen are given to Trans
women. In the medical field, hormone replacement therapy can be used for reducing the high
prevalence of Alzheimer’s disease, especially in men. Hettinger Li and Klein (2018) suggested
that the improvement of vasectomy symptoms, reduction of high rate of colorectal cancer ,
improvement urogenital atrophy, increase in density of bone material, decrease in the risk of
hip fracture and vertebral fracture can be done by hormone replacement therapy. Hence, in
order to apply hormone replacement therapy, blood pressure record, physical examination and
including pelvic examination is required to conduct prior to the application of hormone
replacement therapy.
Conclusion:
Thus it can be concluded that the benefit of hormone replacement therapy is that it
protects against both coronary heart disease and stroke, restoring the wellbeing. It can be acts the
replacement therapy for men who have lost their functions and it can act as the substitution for
other hormones that facilitate gender traits in individuals.

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symptoms. American Research Journal of Endocrinology, 2(1), pp.1-6.
Berryhill, G. E., Trott, J. F., & Hovey, R. C. (2016). Mammary gland development—It’s not just
about estrogen. Journal of dairy science, 99(1), 875-883.
Boron, W. F., and Boulpaep, E. L. 2016. Medical Physiology E-Book. Elsevier Health Sciences.
3rd edition
Bouillon, R., Drucker, D.J., Ferrannini, E., Grinspoon, S., Rosen, C.J. and Zimmet, P., 2015. The
past 10 years—new hormones, new functions, new endocrine organs. Nature Reviews
Endocrinology, 11(11), p.681.
Brisken, C. and Ataca, D., 2015. Endocrine hormones and local signals during the development
of the mouse mammary gland. Wiley Interdisciplinary Reviews: Developmental Biology, 4(3),
pp.181-195.
Ettinger, B., Li, D.K. and Klein, R., 2018. Continuation of postmenopausal hormone replacement
therapy: comparison of cyclic versus continuous combined schedules. Menopause, 25(11),
pp.1187-1190.