Biology Assignment: Human Urinary System - Homeostasis and Kidney

This biology assignment delves into the human urinary system, exploring its anatomy, including the kidneys, ureters, bladder, and urethra, along with their respective functions. The assignment discusses the kidney's role in blood filtration, waste removal, and maintaining fluid balance, including the function of nephrons, renal arteries, and veins. It also addresses kidney replacement therapy, highlighting its importance in treating kidney failure and the factors influencing treatment choices. Homeostasis and negative feedback mechanisms within the urinary system are examined, particularly focusing on the balance of water, salt, and pH. The assignment further explores the impact of sodium and potassium on the body and their roles in maintaining health, alongside the presentation of factors and indicators of normal urine. The assignment provides a comprehensive overview of the urinary system and its critical functions in maintaining overall health.

Running head: BIOLOGY
Biology:
Name of the student:
Name of the university:
Author note:

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Question 1:
Figure 1: Anatomy of the urinary system
Source: National Cancer Institute (2019)
The urinary system of the human body consists of two ureters, two kidneys, urethra and a
bladder.
Kidneys: Kidney is a purplish-brown organ positioned beneath ribs at the posterior wall of the
abdominal part at the waist level. The kidney remains encased within the outer capsule, fibrous
in nature and is termed as a renal capsule (Glassock and Rule 2016).

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The kidney is used to control blood composition and blood value. It is controlled by
filtration, which helps to remove waste, excess water and salt from the blood. These waste are
then secreted by urine.
Ureters: Ureters are the narrow tube which is used to carry urine to urinary bladder from the
kidney. The upper part of the ureter is situated at the abdominal part of the system, whereas, the
lower part is situated in the pelvic area (Mulţescu et al. 2016).
The main function of the ureter is to pass down the urine. Hence, to pass the urine from
the kidney to the bladder, the muscles of the ureter start tightening continuously and relaxing
subsequently away from kidney.
Bladder: Urinary bladder is triangle shaped organ which is hollow in structure and is located at
the lower abdomen level. The bladder is held in its position by the help of ligaments which
remain attached to the pelvic bones and other organs.
The main function of the urinary bladder is to store urine. The urine is stored in the
urinary bladder by expanding and relaxing the walls of the bladder. When the urine needs to be
excreted from the body, the walls of the bladder starts contracting. A healthy bladder can store
the urine for about 2 to 5 hours.
Urethra: Urethra is a small tube-like structure that helps the urine to be excreted from the body
from the bladder. It is situated below the urinary bladder (Tortora and Derrickson 2017).
The primary function of the urethra is to excrete the urine out of the body. It is done by
tightening the muscle, which is done by triggering the brain signal. The bladder squeezes the
urine out of the body.

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Sphincter muscle: These muscles are circular in shape which prevents the leakage of urine by
tightly closing the rubber band present around the bladder’s opening.
Blood supply: The blood supply of the urinary systems is done mainly through the inferior and
the superior vesical arteries. These arteries indirectly or directly arising from the artery named as
an internal iliac artery.
The urinary bladder functions by the help of signals received from the brain. The urinary
bladder is supplied with different branches which include, sensory fibres which are enthused by
extending, instigating a consciousness of fullness and triggering reflexes, parasympathetic
motorfibres toward the detrusor and sympathetic fibres to the blood vessels (McBride 2016).
Question 2:
A. Diagram of kidney

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B. Ureter: It is a tube-like structure which collects the urine and filtrate from the renal
pelvis region and carries it to the bladder from where the urine is excreted from the body.
Renal artery: It is branched from the aorta, which brings the blood filled with waste.
The blood is carried to the kidney for the filtration in the nephron. Some renal arteries
also help in kidney nourishment.
Renal vein: Renal vein is used to remove the blood after filtration to the inferior vena
cava region from the kidney.
Renal nephron: It is the functional unit of the kidney which helps in the regulation of
soluble substances from the blood by the help of filtration, reabsorbing the essential parts
and the remaining parts have been excreted.
Renal artery, renal nephron and the renal vein together called as renal hilum.
Renal pelvis: It is basin like region which aids in the collection of the urine from the
different nephrons.
Medulla: This is the internal region of the kidney, which is divided into the different
number of section. Medulla helps in the reabsorption of the water.
Capsule: Renal capsule is a membranous structure which covers the surface of the
kidney. It provides support to the kidney and protect the kidney from any vital injury.
Major calyx and Minor calyx: Two or more minor calyx converge together to form a
major calyx. The urine passes through it before passing to the ureter (Liu et al. 2019).
Cortex: It is the outer region of the kidney which contains about millions of nephrons
responsible for filtration. It is the part of the kidney where the ultrafiltration occurs.

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Pyramids: The aid of collecting ducts forms renal pyramids. The primary function of the
renal pyramid is to transport the urine to the different parts of the kidney
Papilla: Renal papillae is considered as the collecting ducts where the pyramids empty
the urine and are secreted to the minor calyx. It is a type of channel (Al-Harbi and
Winyard, 2016).
C. Tubular system of the kidney:
Each nephron consists of different parts such as renal corpuscle, nephronic loop
(ascending and descending loop of Henle), the proximal tubule and the distal tubule. The primary
function of the nephron is to remove the waste such as urea, creatinine, and excess of sodium,
potassium and chloride ions. After the reabsorption, the electrolytes are carried back into the
blood. The blood is carried to the nephron with the help of different arteries. The blood flows
through the network of the capillaries, which is named as, glomerulus (Pourghasem, Shafi and
Babazadeh 2015). One-fifth of the total plasma which is filtered through the membrane structure
named as the glomerular membrane is collected in to the Malpighian capsule, which covers the
glomerulus. The plasma is then passed through the proximal tubule and then is passed to the loop
of Henle, after that into the distal tubule and is finally collected into the collecting tubule. During
this transportation, most of water and solutes are again absorbed to the blood through peritubular
capillaries (O'Callaghan 2016). The part of the solutes and water which remains into the tubules
forms urine.
Question 3:
Kidney replacement therapy is one of the widely used methods in the case of kidney
failure. It is a therapy that replaces the normal function of the kidney, which is the filtration of

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the blood. It is occasionally for some types of poisoning (Zarbock and Mehta 2019). These
techniques include peritoneal dialysis, intermittent hemodialysis and continuous hemofiltration,
which helps in the filtration of the blood. It is used when the kidney of an individual is not able
to work properly, or the person suffers from chronic kidney disease and acute kidney injury.
According to kidney.org (2019), kidney replacement therapy also includes kidney
transplantation, which is one of the ultimate forms of replacement.
In the medical field, it has contributed a lot as it helps in the treatment of the patient who
has been suffering from chronic kidney complication. According to Niddk.nih.gov (2019), this
therapy do not fully cure the kidney disease but is considered as the life-extending treatment. In
some cases, the disease can be easily managed with the help of dialysis, but if not managed
effectively with the help of dialysis, kidney replacement therapy is used (Ronco et al. 2015). In
some cases, it is observed that the patient who has been treated with this therapy have faced no
complication regarding the kidney in their future life. Though this treatment not fully cures the
disease, it is considered to be more reliable than that of the dialysis and other treatment (Wald et
al. 2015).
The choice of this therapy for the treatment of the person suffering from kidney disease
depends upon the several factors such as the primary need of the patient, underlying condition,
vascular disease, availability, patient preferences, capability, and hemodynamic stability due to
this method the life-expectancy rate of the population increases (Barbar et al. 2018).
Question 4:

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A. Homeostasis is considered as the process where the body of the human constantly controls a
variable to maintain it to a specific point. When the variable of the homeostasis changes, the
body initiates the mechanism to reverse it back to the specific point. During homeostasis, the
blood pressure and other physical condition of the body fluctuate continuously. This
fluctuation can be controlled and monitored by the help of negative feedback (Cianciolo and
Mohr 2015). Control centres in the different parts and brain of the body react and follow to
deviation from hemostasis by using negative feedback. Negative feedback deviates the
reversion from the set point. It helps to maintain the normal body temperature. In the urinary
system, the homeostasis is regulated by the amount and composition of the blood. The kidney
filters the waste from the bloodstream and prevents its reabsorption in the body. Kidney
plays an essential role in maintaining the fluid balance (Drolet 2019). To maintain the fluid
balance, a urinary system with the help of homeostasis enhances or reduces the amount of
water in urine.

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Insufficient water
in the body
Blood volume
decreases
Blood osmolarity is
increased
Blood pressure
decreases
Osmoreceptors in the
hypothalamus is triggered
Dry mouth
Angiotensin II
increases
Thirst center present in the hypothalamus is
increased
Thirst is increased
Water is taken into
the body

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Figure: Hemostasis of the fluid balance
B. Role of the kidney in the balance of salt, water and pH:
According to NIH.GOV (2019), excess salt in the diet can cause an increase in
glucocorticoids and the aldosterone, which are responsible for controlling the water, salt
balance in the body. These hormones affect the kidney as increased consumption of sodium
increase the sodium excretion and maintain water balance. Excess sodium in the body leads
to more concentrated urine. In order to avoid that kidney releases less sodium into the urine
whereas, more water is released from the body as urine. The excess water is removed from
the body via filtration.
The kidney also plays an important role in pH maintenance or the acid-base balance
mechanism. High pH in the kidney can lead to kidney stones or another disease. To reduce
high acidity in the urine, the kidney reabsorbs bicarbonate ion from the urine and to maintain
alkalosis; the kidney excretes the hydrogen ion into the urine (Oh and Briefel 2017).
Question 5:
Sodium and potassium both are one of the major ions present in the extracellular fluid. If
excess sodium is present in the body, it increases the risk of hypertension. Sodium and potassium
are half of the electrical pump present at the cell level, due to which the sodium remains around
the plasma, and the potassium remain inside the cell (Sterns 2015). It also affects the
bloodstream and prevents the kidney from removing excess water from the body, which can lead
to kidney disease.
Blood osmolarity is decreased

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When the intake of sodium is increased in to the blood, dehydration occurs. It occurs due
to less water and a high amount of salt. Symptoms observed are diarrhoea, vomiting, excessive
sweating and fever. Hyponatremia (excess water and excess salt) leads to dilution of salt in to the
blood and increases the risk of cancer, thyroid and pneumonia.
Potassium is present inside the cell in the most concentrated form. The difference in the
level of potassium in the cell is compared to the plasma, which is essential for the generation of
electrical impulse in the cells and it also aids the muscle and brain to function correctly (Viera
and Wouk 2015)
Potassium imbalance in the body is observed by various signs and symptoms, which
include, fatigue, weakness, muscle aches, numbness, breathing complications, tingling, muscle
cramps and digestive problems.
Question 6:
A.
Presenting
factors
Normal urine
indicators
If present, what
would this be an
indicator of?
Citation (Name,
Year) List fully at the
end.
Colour Straw colour The colour of the
urine straw colour,
which is due to the
presence of the
dietary substance.
However, if the
colour of the urine
deepens or darkens, it
can be stated that the
body has been
dehydrated and needs
more fluid. If the
Kavouras et al.
2016

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urine sample was
clear, it could be
noted that the body
might havean excess
of water. If the urine
sample was red, it
could be stated that
the person might be
suffering from
urinary tract
information as the red
colour is due to the
blood.
Odour During the normal
condition, the
fragrance of the
urine has a stronger
ammonia scent.
If the odour of the
urine has a smell of
ammonia, it can be
stated that the urine
of the person is
normal and have no
disease. If the urine
sample has a sweet
smell, it indicates that
the person has excess
glucose in the blood.
Andreev et al. 2017
Protein Proteins are usually
not present in urine.
If the sample of the
urine indicates
protein, the person
might have been
suffering from kidney
complication. The
kidney is not able to
filter properly.
Hermida et al. 2016
pH The normal pH of
the urine depends
upon the diet of the
person which
ranges in 5-7.
If the pH of the
sample is above
seven it is low acidic,
and if it is under five
it is too acidic. If the
acidity is abnormal,
the patient might
have urinary tract
Menezes et al. 2019