PART mechanism known as the feedback regulation. This is


Explain and Evaluate homeostasis in
the human body.
Word Count Limit:
1500 – 2000 words
Roughly 300-400 words to each question.

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Importance of homeostasis within the
human body

in short, is the stable condition of an organism and its internal environment,
it maintains the equilibrium and balance of functions of the human body, which
the nervous system and hormones are responsible for. Maintaining balance is
critical in keeping the body alive and healthy. To do that, the cells must be
kept in perfect conditions to function and survive. Homeostasis is in important
in the human body. One reason is that certain chemicals such as oxygen (O2) and
carbon dioxide (CO2) and food that is digested exit and enter cells using
osmosis and diffusion. Diffusion is essentially the passive movement of
molecules from a place of high concentration to a place of low concentration.
Osmosis on the other hand is the movement of water from a dilute to a more of a
concentrated solution through a partially permeable membrane. Active transport
also moves chemicals such as a glucose as well. If there is excess water that
finds its way into a cell by the process of osmosis, the cell membrane can
actually rupture but if there is too much water movement out of the cells they
will not be able to function as they should. For both osmosis and diffusion to
work as they should, homeostasis is needed to help keep our body (and water and
salt level) balanced. Homeostasis helps keep enzymes functioning properly by
maintaining the correct body temperature. Without the temperature being
controlled the enzymes would not be able function as they should and as a
consequence cells would die.
To resist any change that happens in or out of an organism environment the mechanisms
to attain homeostasis are stable. Depending on the individual, the mechanisms
can vary and can either be negative or positive feedback.

Explanation of how the endocrine
system is involved in homeostasis

homeostasis hormones will control the activity of body cells which the
endocrine system is responsible for. Its done via a self-regulating mechanism
known as the feedback regulation.
This is when a stimulus controls the release of hormones into the blood stream.
There can be either an increase of decrease by the stimulus of the number of
hormones that are being secreted. It can then become a new stimulus as the
response to the original stimuli changed the internal environment.  The feedback part of the regulation happens
when the response to a stimulus influences the original stimuli. Dependant on
the response type will determine what feedback is called. There is both
Positive Feedback and Negative Feedback.
Positive Feedback is when there is an increase of the original stimulus due to
the response. Negative Feedback is when the stimulus response reduces the
original stimulus.

Out of the
two, negative feedback is far more common. It is a system that reacts to
reverse change. Due to this, the maintenance is lowed for the balance of

The process of Osmoregulation is
by which the body keeps homeostasis of an organism’s water level constant by
regulating the osmotic pressure of any organism fluids. In short osmoregulation
is used to prevent the bodily fluid from being either too concentrated or too
diluted. To measure the ability of water to move from one solution to another
solution via osmosis, an osmotic pressure is used. Osmotic pressure is when a
liquid solution diffuses, thereby moving from a lower concentration to a higher
concentration across a membrane. For humans it is critical to have the osmotic
pressure maintained. There is no loss or gain of fluids or salts into the cells
of the body as osmotic pressure gained an isotonic solution. Instead there is a
constant and steady in and out of the cell membrane of substances.
When the water level in the blood drops below normal range the hypothalamus detects
the change and the higher concentration of solutes in the blood. When this
occurs, two things happen. Firstly the hypothalamus creates a feeling of thirst
and the pituitary gland releases more ADH to stimulate the kidney’s into
absorbing more water when the person drinks, which helps restore the balance in
the in the body.


At least 3 examples
of homeostasis within the human body

A good
example of this would be the regulation of carbon dioxide in the human body.
Carbon Dioxide is a waste product of respiration. It travels in the bloodstream
from the cells to the lungs and leaves our body when we exhale. Carbon Dioxide
when it is dissolved in water forms an acidic solution. In order to prevent the
blood from becoming too acidic or too alkaline the Carbon Dioxide levels must
be controlled. The pH of blood can be affected if Carbon Dioxide is allowed to
overproduce. This would then affect many blood proteins and more specifically
the enzymes. Other critical processes such as clotting of the blood could be
affected. To start with something disturbs the homeostasis, either there is too
much or too little CO2 being produced. As an example I will use too much CO2.
When there is too much CO2 the pH of the blood will decrease and the O2 levels
in the blood will decrease too as well as in the cerebral spinal fluid. After
the disturbance there will be a reflex response. In this instance chemoreceptors
are stimulated which then leads to a respiratory response. In the respiratory
response the medulla oblongata is stimulated and the respiratory rate
increases. Homeostasis is then restored and the oxygen and pH return to normal

example is thermoregulation. This is where homeostasis assists in adjusting and
regulating body temperature and responding to changes in the surrounds. If the
body temperature falls, homeostasis will trigger a response in the body.
Firstly the blood vessels will constrict so heat can be retained for longer. At
this time, your body will not allow sweat glands to secrete any fluid but
instead your body will start to shiver; an involuntary response that creates
heat and in turn raises the body temperature.

A final
example would be the regulation of glucose in the human body. It is important for
our body to regulate our glucose/sugar. If we have too little it can trigger hypoglycaemia
(causes dizziness, sickness and extreme cases cause a coma) and likewise if
there is too much it can cause hyperglycaemia, and if too often can be a sign
of Diabetes. In homeostasis, if blood sugar becomes over a safe level insulin will
be secreted from the pancreas to correct this and bring blood sugar level back
down. Again, if blood sugar level becomes too low homeostasis will trigger a
response form the pancreas again, releasing glucagon to up the sugar levels to
a safe level.





An explanation of how
each of the key organ systems work together and contribute to overall
functioning of the human body.

Our body works together in order to keep us healthy and
functioning. The cardiovascular system works with our respiratory system to
spread oxygen throughout the body and rid itself of waste carbon dioxide (CO2).
The cardiovascular system uses its system of arteries and veins and heart to
pump oxygen-filled blood from the lungs to rest of the body, giving oxygen to
the organs and tissues. Once the organs and other body cells have taken their
oxygen (O2) they release carbon dioxide (CO2) back into the blood which will
flow through the veins back to the heart via its right-side chambers. Once
through the right chambers it flows back to the lungs to exchange the waste
carbon dioxide (CO2) for oxygen (O2). The now inhaled oxygen flows through the
nasal pathways down towards the throat and onto the lungs. It then goes to
alveoli where gas exchange happens. The oxygen travels through the blood from
the lungs to hearts left chambers and is pumped with great force via the
arteries to deliver oxygen to the organs and body cells that need oxygen. This
is a cycle that continues throughout a person’s lifetime. To link further to
other body systems, both the nervous system and endocrine system both regulate
the cardiovascular system.

Its not just the cardiovascular system and respiratory system
that work together; the digestive system and excretory systems also work
together. The digestive system’s role is to break down food into molecules that
are small enough for our body tissues and cells to use. The stomach breaks the
food apart and down by churning but also by releasing enzymes. Once through the
stomach the food moves onto the small intestine where pancreatic juices and
enzymes are received which are designed to dissolve and digest fats,
carbohydrates and fibres. Fats are dissolved by the bile which is produced by
the liver. The small intestines’ main function is absorption.  Nutrients which are digestible are passed
through the small intestine and the microvilli to the capillaries and finally
arriving at the liver for detoxing and final processing before being released
to the rest of the body. Not everything is digested however, and some material
such as fibres, bile and bacteria journey through the large intestine and out
the colon and rectum. Urine is formed from the kidneys that filter out waste
from the blood. The urine flows through the ureters and then enters the bladder.
When full the bladder releases urine and its exits the body via the urethra. Again,
much like the cardiovascular and respiratory system, the digestive and
excretory systems are both regulated by the nervous and endocrine system.

To link it all together, the cardiovascular system supplies
oxygen rich blood to the rest of the organ systems, sustaining them. Without
the cardiovascular system providing the oxygen the other systems would not be
able to function properly. They would die. The cardiovascular system not only
provides oxygen, it also removed waste products such as carbon dioxide (CO2) and
brings it back through the blood and expels it out of the lungs.




Compare and Contrast
how the endocrine system and nervous system help control our body functions.

Nervous system uses electrical impulses (action potentials)
as signals whereas the Endocrine System uses chemical impulses (hormones) to
communicate with the body. Nervous system pathways is transmission by neurons
whereas the endocrine system transports the hormones through the blood. The
endocrine is rather slow in the speed of information, but the nervous system is
fast. Nervous system duration is short lived, but endocrine can either be long
or short lived. Endocrine is always an involuntary action/response, but the
nervous system can either be voluntary or involuntary action/response. The
target of the nervous system is localized which is cells that are connected to
neuron. Endocrine system targets are often distant and many cells can be

The nervous system is made up of neurones and they use
electrical impulses as a form of transmission. The nervous system uses nerve
fibres such as the axons and dendrons as a transmission pathway to communicate
with the human body. Although the speed of the transmission is fast the
duration of effect is short term and the response is localised and not

The endocrine system is made up of secretory cells and uses
hormones (chemicals) as a form of transmission. The endocrine system transports
the hormones via the blood stream. Unlike the nervous system the speed of
transmission is slow but the duration of effect is long-term and widespread,
but it can target a specific organ.