Biology Assignment

This report would discuss some of the major organ systems such as the circulatory system, nervous system, digestive system and the excretory system and talk about how the organ systems are dependent upon one another to carry out the normal physiological functions such as homeostasis. Further, the paper would also discuss the relationship of the endocrine system in maintaining homeostasis and compare between the endocrine and nervous system to establish a strong concept about the physiological processes.

Running head: BIOLOGY ASSIGNMENT
BIOLOGY ASSIGNMENT
Name of the Student:
Name of the University:
Author Note:

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Executive Summary:
This report would discuss some of the major organ systems such as the circulatory
system, nervous system, digestive system and the excretory system and talk about how the
organ systems are dependent upon one another to carry out the normal physiological
functions such as homeostasis. Further, the paper would also discuss the relationship of the
endocrine system in maintaining homeostasis and compare between the endocrine and
nervous system to establish a strong concept about the physiological processes.

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Table of Contents
Introduction:...............................................................................................................................3
Explanation of the functioning of the Organ Systems:..............................................................3
Cardiovascular system and Digestive System:..........................................................................3
Explanation of Homeostatic Control Mechanism:.....................................................................7
Explanation of endocrine system in homeostasis:.....................................................................7
Comparison of endocrine and nervous system:.........................................................................8
Conclusion:................................................................................................................................9
References:...............................................................................................................................10

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Introduction:
The human body comprises of a sum total of ten organ systems that are
interconnected and dependent on one another for the normal physiological functioning of the
human body. For instance, the skeletal system relies upon the nutrients supplied by the
digestive system and the nervous system controls the movement of the muscles. Therefore,
this paper would discuss the important physiological functioning of the major systems of the
human body.
Explanation of the functioning of the Organ Systems:
Cardiovascular system and Digestive System:
“The effect of activity on heart rate and digestion” is critically maintained by the coordinated
functioning of the circulatory system with the digestive system. The circulatory system
comprises of the heart, blood vessels, lymph, blood, lymphatic vessel and glands (Sherwood
2015). The system is responsible for circulating oxygenated blood and transporting nutrients
across various organs of the body. The Lymph is a tissue fluid that forms an essential part of
the circulatory system, which is added to the venous blood through the lymphatic vessels.
The digestive system comprises of the buccal cavity, oesophagus, stomach, small and
large intestines, liver, gall bladder, pancreas and the rectum. The digestive system helps in
digestion by breaking down complex macromolecules of the food particles into simple
molecules that are assimilated in the body to generate energy.
The ingested solid food is broken down into chyme which is equivalent to a fluid like
mixture and the chyme is then introduced to the small intestine. The small intestine comprises
of finger like projections, known as the villi that absorb glucose from the fluid mixture and

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present it the blood vessels of the circulatory system. The absorbed glucose is then
transmitted by the blood to different organs of the body in combination with oxygen that is
supplied by the lungs. It should be noted here that the oxygen and glucose combine with one
another within the mitochondrial unit of the cell and the combination occurs by virtue of a
chemical reaction. The reaction is known as cellular respiration and it involves the formation
of one ATP molecule, which provides energy to the cells to carry out various physiological
functions. Carbon Dioxide and water forms the by product of the reaction that are released
into the bloodstream and subsequently disposed by the excretory organs (Pocock et al. 2013).
Thus, it can be said that the circulatory system helps in transporting the nutrients produced by
the digestive system to the different parts of the body and at the same time, the digestive
system supplies the energy to maintain the functioning of the circulatory system.
Endocrine System: “The effect of ingestion of a meal on blood glucose level” is monitored
by the functioning of the endocrine system. The digestive functions is closely regulated by
the endocrine system with the help of the hormones. Hormones can be defined as chemical
messengers that are secreted into the blood stream and work on target cells by modifying
their physiology. The pancreas comprise of the islets of Langerhans that secrete essential
hormones into the blood stream and regulate the physiology of glucose metabolism within the
human body. The two important hormones that are secreted by the pancreas include the
Glucose and the Glucagon which are responsible for maintaining the levels of the blood
sugar. The maintenance of blood sugar level is integral for the normal functioning of the vital
organs of the body that include, the brain, liver and the kidneys. In this regard, it should be
mentioned that insulin is responsible for lowering the blood sugar level whereas, glucagon
raises the blood sugar level (Schwartz et al. 2013). The blood glucose level varies with the
frequency of food intake over a period of 24 hours. The body enters the absorptive phase
after absorbing the nutrients from the gut and as a result the blood-glucose level elevates

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which is balanced by the stored glucose present in the liver. Once the digestion process is
complete, the absorption rate of the nutrients decreases and as a result the stored glucose is
used for the generation of energy and this results in lower blood-glucose level. It is important
to note here, that blood sugar level less than 140mg/dL (7.8mmom/L) is considered normal
and the body should maintain the range in order to avoid the probabilities of hyperglycaemia
and hypoglycaemia (Shwartz et al. 2013). The glucose levels significantly vary during the
absorptive stage in accordance to the quantity of the food intake and this serves as the
rationale why post-absorptive fating state glucose levels are used for the assessment of blood
glucose level. The normal range of blood glucose must be maintained between 3.3 to
6.1mmol/L (Shwartz et al. 2013). A result outside the mentioned range indicates the
condition of Diabetes mellitus. Also, within the absorptive stage there is an increased level of
blood glucose which triggers the beta cells of the islets of Langerhans located within the
pancreas to secrete insulin which stimulates the muscle cells and the adipose tissue to uptake
glucose from the blood. The body enters the post-absorptive stage after several hours of food
consumption and subsequently the insulin level drops. This lowers the blood glucose level
and triggers the release of the hormone glucagon from the alpha cells of the pancreas which
increases the blood glucose level (utilizing the glycogen stored in the liver) and activates
inhibitory processes that prevent the utilization of glucose.
Excretory System and Osmoregulation: “The role of excretory system in excretion and
osmoregulation” can be explained with an insight to the functioning of the excretory system.
The functional unit of the excretory system are the pair of bean-shaped structures known as
the kidneys that are placed within the peritoneal cavity, posterior to the liver. The kidneys are
responsible for maintaining the osmotic pressure of the blood through the process of
osmoregulation. The process is regulated through repeated filtration and purification. The
kidneys are responsible for the process of elimination of body waste through urination under

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the action of the hormones antidiuretic hormone, aldosterone and angiotensin II. These
hormones help in increasing the permeability of the collecting ducts that facilitate convenient
diffusion. Further, the action of the hormones also help in reabsorbing water and thus
maintain a balance between the retained water and amount excreted through urine or sweat.
Osmoregulation can be defined as the regulation of the osmotic pressure of the body fluids,
detected by the osmoreceptors to maintain the process of homeostasis (Kotas and Medzhitov
2015). The phenomenon of osmoregulation is a combined effect of antidiuresis as well as
natriuresus. It should be noted that the osmoregulator cells are located within the basal
forebrain. These cells can strongly sense the minute fluctuations with respect to plasma
osmolarity (Ang and McMillen 2013). The process of reabsorption is governed by the
stimulus generated by the Na+ receptor cells that inhibit the process of salt intake during
dehydration and helps in the maintenance of osmoregulation. Also, the process of diuresis
governs osmoregulation during overhydration.
Musculoskeletal System and Nervous Control: “The role of nervous system in relation to
activities and other systems” The muscular functions are tightly regulated by the peripheral
nervous system that form an extension of the central nervous system. The brain and the
spinal cord form the major components of the CNS and the PNS extends from the CNS to the
limbs and other parts of the body. The Peripheral nervous system is subdivided into the
autonomic nervous system and the somatic nervous system which regulate the functioning of
the skeletal muscles as well as the cardiac and the smooth muscle fibres respectively
(Burnstock and Costa 2013). The somatic nervous critically controls the voluntary
movements of the arms and the legs during walking or writing. It also perceives sensory
stimuli in the form of touch, smell or vision. The nerves that control the functioning of the
skeletal muscles are known as motor neurons. The SNS is majorly concerned with the
transmission of neuronal impulse from the brain to a concerned body part that results in a

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movement. The muscular coordination also involves a complex role of the sensory neurons.
For instance, while catching a ball, the brain first receives a sensory feedback and directs the
hand to catch the ball. The sensory perception notices the positioning of the ball with time
and the brain regulates the correct positioning of the hands and the fingers to catch the ball.
Therefore, the nervous system closely regulated the muscle movement and coordination
during different physical activities.
Explanation of Homeostatic Control Mechanism:
The process of homeostasis in humans can be defined as the process by which
optimum temperature is maintained within the body in accordance to the external
environment so as to maintain a constant range of body temperature. The homeostasis
mechanism is governed by three vital components that include the receptor, the integrating
centre and the effector. The receptor acts by sensing the environmental stimulus and
conveying the perceived information to the integrating centre. The integrating centre is the
hypothalamus located within the brain which on receiving the stimulus sends the signal
message to the effector muscles to respond to the stimuli. The response can either be
generated through the positive feedback loop or the negative feedback loop. The positive
feedback acts by accelerating the output action generated by an external stimuli. For instance,
accumulation of platelets within an injured area in response to injury and pain is a result of
the positive feedback loop (Pocock et al. 2013). On the other hand, the negative feedback
loop is responsible for normalising physiological functions such as regulation of blood
pressure and blood glucose level. It should also be note din thus context that homeostatic
imbalance could lead to a number of health issues. Also, the process of ageing gradually
impairs the functional ability of the feedback loops which could lead to cardiac problems.
Diabetes is a chronic illness that manifests itself because of poor regulatory mechanism of

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glucose. Thus, homeostasis helps in maintaining the optimum temperature and pH
concentration of the internal environment.
Explanation of endocrine system in homeostasis:
The endocrine system comprises of the ductless glands that synthesise hormones and
pour them into the blood stream. The synthesized hormones maintain the normal functioning
of the feedback loops. The pituitary gland, the pineal gland, the testes, ovaries, pancreas,
adrenals, thyroid and parathyroid are the major endocrine glands of the human body. The
hypothalamus-pituitary complex present within the brain is responsible for maintaining the
normal functioning of the endocrine system. The positive and the negative feedback loops in
homeostasis is maintained by a chain of hormone reactions that are under the direct control of
the endocrine glands. For instance, the negative feedback loop is concerned with the reversal
of the normal physiological functioning (Pocock et al. 2013). On sensing the presence of the
optimal level of hormone within the bloodstream, the hypothalamus and the pituitary are
signalled to stop the production of the hormone (Rizzo 2015). Also, on sensing a deficiency
of a particular hormone, the hypothalamus and the pituitary are signalled to enhance the
production of the hormone. For example, on sensing an increased temperature due to
strenuous workout, the body temperature is lowered in accordance to the negative feedback
loop. On the other hand, the concentration of the hormone Oxytocin is increased during
childbirth to reach complete dilation of the cervix and stronger contractions.
Comparison of endocrine and nervous system:
The endocrine system and the nervous system differ among one another in the
following ways:

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The nervous system makes use of the electric impulse to transmit signalling from one neuron
to another, whereas the endocrine system makes use of chemical messengers or hormones to
signal the target cells. Transmission of nerve impulse is spontaneous but temporary, whereas
transmission through hormonal regulation is long lasting but requires a longer time period to
act (Sherwood 2015). Also, the responses are localized and specific in case of nerve impulse
transmission (Watson 2014). However, the responses are extremely widespread and amplified
in case of hormonal action. Also, most of the responses in case of nervous system are
reversible but the responses are generally irreversible in case of the hormonal response
directed by the endocrine system. However, it should be noted here that both the systems are
interdependent on one another for a wide range of normal physiological functions.
Conclusion:
Therefore, to conclude, it should be mentioned that the normal physiological
functions are critically maintained by the coordination and intercommunication of diverse
organ systems. Thus, the organ systems work collectively to maintain a stable equilibrium
and prevent the body from acquiring any infections that could interfere with the normal
functioning of the immune system.

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References:
Ang, J. and McMillen, D.R., 2013. Physical constraints on biological integral control design
for homeostasis and sensory adaptation. Biophysical journal, 104(2), pp.505-515.
Burnstock, G. and Costa, M., 2013. Adrenergic neurons: their organization, function and
development in the peripheral nervous system. Springer.pp.53
Hall, J.E., 2015. Guyton and Hall textbook of medical physiology e-Book. Elsevier Health
Sciences.pp.77-79
Kotas, M.E. and Medzhitov, R., 2015. Homeostasis, inflammation, and disease
susceptibility. Cell, 160(5), pp.816-827.
Pocock, G., Richards, C.D. and Richards, D.A., 2013. Human physiology. Oxford university
press.pp.38-41
Rizzo, D.C., 2015. Fundamentals of anatomy and physiology. Cengage Learning.pp.67-69
Schwartz, M.W., Seeley, R.J., Tschöp, M.H., Woods, S.C., Morton, G.J., Myers, M.G. and
D’alessio, D., 2013. Cooperation between brain and islet in glucose homeostasis and
diabetes. Nature, 503(7474), p.59.
Sherwood, L., 2015. Human physiology: from cells to systems. Cengage learning.pp.98
Watson, C., 2014. Human physiology. Jones & Bartlett Publishers.pp.53