Jinan Ahmed

XI ‘D’

EXCRETORY
PRODUCTS AND
THEIR
ELIMINATION
Thesis
NAME: JINAN AHMED
CLASS: X1 ‘D’
‘DATE: 21/09/2023
SUBJECT: BIOLOGY
ACKNOWLEDGEMENT
I would like to express my gratitude to my
teachers who gave me the golden
opportunity to do this wonderful project on
the topic 'To create awareness on the human
excretory system.
I gained so much information while doing this
project.
Secondly, I would also like to thank my
parents for supporting and helping me to
finalize this project in time.
 INDEX
S.No TITLE DATE
1 cover page

2 ACKNOWLEDGEMENT
3 INDEX
4 introduction

5 thesis

6 conclusion

7 2 case studies
8 newspaper articles
9 BIBLIOGRAPHY
 INTRODUCTION

Life of every organism depends on

certain basic processes. Excretion is one
among them. Different organisms follow
different modes of excretion. In complex
organisms including humans, there is a
specialized system for excretion called
human excretory system.
 Excretion
We all obtain our nutrients from
different sources which are later
digested and metabolized in our body.
After metabolic reactions, the body
starts to sort out useful and toxic
substances in an individual. As we all
know, the accumulation of the toxins
may be harmful and the body removes
all the metabolic wastes by the process
called excretion.
 EXCRETION IN VARIOUS
ORGANISMS

Different organisms follow different modes

of excretion such as kidney, lungs, skin and
eyes depending on their habitat and food
habit.
For example- Aquatic animals excrete waste
in the form of ammonia, while birds and
insects excrete mainly uric acid. Humans
produce urea as the major excretory
product.
Excretory System Organs
The human excretory system
organs include:
A pair of kidneys
A pair of ureters
A urinary bladder
A urethra
 Kidneys
Kidneys are bean-shaped structures
located on either side of the
backbone and are protected by the
ribs and muscles of the back. Each
human adult kidney has a length of
10-12 cm, a width of 5-7 cm and
weighs around 120-170g.
 Kidneys
The kidneys have an inner concave
structure. The blood vessels, ureter and
nerves enter the kidneys through the
hilum, which is a notch at the inner
concave surface of the kidney. The renal
pelvis, a large funnel-shaped space is
present inner to the hilum, is has many
projections known as calyces.
 STRUCTURE
OF KIDNEY

CAPSULE
The outer layer is called the capsule.

Inside the kidney, there are two

zones- the outer zone is the cortex

and the inner zone is the medulla.

The cortex extends in between the

medullary pyramids as renal columns

called columns of Bertin.

 Nephrons
Nephrons are the functional units of the kidney.
Each nephron has two parts- glomerulus and
renal tubule.
Glomerulus consists of a bunch of capillaries
formed by afferent arterioles. Blood from
glomerulus is carried away by efferent
arterioles.
The renal tubule starts with a cup-like structure
called Bowman’s capsule and this encloses the
glomerulus. The malpighian body consists of
glomerulus and Bowman’s capsule. The highly
coiled structure in the tubule next to the
Bowman’s capsule is the proximal convoluted
tubule.
 Henle’s Loop

The next part of the tubule is Henle’s loop

which has an ascending and a descending limb.
The ascending loop continues as a distal
convoluted tubule. The distal convoluted
tubules of many nephrons open into the
collecting duct.
 Ureter

A pair of thin muscular

tubes called the ureter
comes out of each kidney
extending from the renal
pelvis. It carries urine from
the kidney to the urinary
bladder.
It is a muscular sac-like structure,

which stores urine. The urinary

bladder is emptied by the process of

micturition, i.e. the act of urination.

 Urethra
This tube arises from the urinary bladder
and helps to expel urine out of the body. In
males, it acts as the common route for
sperms and urine. Its opening is guarded by
sphincter muscles.
 EXCRETION
Excretion is the process where all the
metabolic wastes are removed from the body.
Excretion in humans is carried through
different body parts and internal organs in a
series of processes.

Diffusion is the most common process of

excretion in lower organisms. A human body is
an exceptional machine, where different life-
processes (respiration, circulation, digestion,
etc.) take place simultaneously. As a result,
many waste products produced in our body
are in various forms that include carbon
dioxide, water, and nitrogenous products like
urea, ammonia, and uric acid.
 In addition to these, the chemicals and other toxic
compounds from medications and hormonal products are
also produced. Simple diffusion is not sufficient to
eliminate these wastes from our body. We need more
complex and specific processes in order to eliminate
waste products.
Blood contains both useful and harmful substances.
Hence, we have kidneys which separate useful
substances by reabsorption and toxic substances by
producing urine.
Kidney has a structural filtration unit called nephron
where the blood is filtered. Each kidney contains a
million nephrons.
 Capillaries of kidneys filter the blood and the
essential substances like glucose, amino acids,
salts, and the required amount of water get
reabsorbed and the blood goes into
circulation.
Excess water and nitrogenous waste in humans
are converted to urine. Urine thus produced is
passed to the urinary bladder via the ureters. The
urinary bladder is under the control of the
Central Nervous System. The brain signals the
urinary bladder to contract and through the
urinary opening called the urethra, we excrete
the urine.
 Mechanism
of Excretion
in Humans

The process of Urine Formation takes place in the

following steps:
Glomerular Filtration
Tubular Reabsorption
Secretion
glomerular FILTRATION

It is the primary step in urine

formation. In this process, the excess
fluid and waste products from the
kidney are filtered out of the blood
into the urine collection tubules of
the kidney and eliminated out of the
body.
The amount of filtrate produced by
the kidneys every minute is known as
Glomerular Filtration Rate (GFR).
 Tubular

Reabsorption

It is the absorption of ions and molecules such as

sodium ions, glucose, amino acids, water etc. Water
involves passive absorption, while glucose and
sodium ions are absorbed by an active process.
 Secretion
Potassium ions, hydrogen ions, and ammonia are secreted
out to maintain the equilibrium between the body fluids.

The functions of the various tubules involved in the

process are:
1. Glomerulus- filters the blood
2. Proximal Convoluted Tubules (PCT)- reabsorb water,
ions and nutrients. They remove toxins and help in
maintaining the ionic balance and pH of the body fluids
by secretion of potassium, hydrogen and ammonia to
filtrate and reabsorbing bicarbonate ions from the
filtrate.
 3. Descending Loop of Henle-
is permeable to water and the filtrate gets
concentrated as it is impermeable to
electrolytes.

4. Ascending Loop of Henle-

it is impermeable to water and permeable to
electrolytes. The filtrate gets diluted due
to the movement of electrolytes from the
filtrate to the medullary fluid.
 5. Distal Convoluted Tubule (DCT)- allows
reabsorption of water and sodium ions. It also helps
in maintaining pH and ionic balance by secretion and
reabsorption of ions like PCT.

6. Collecting Duct- a large amount of water is

reabsorbed from the filtrate by the collecting duct.
 Micturition

The urinary bladder is stretched and gets

filled with urine formed in the nephrons.
The receptors present on the walls of the
urinary bladder send signals to the Central
Nervous System, thereby, allowing the
relaxation of sphincter muscles to release
urine. This is known as micturition.
 Dialysis
Under certain circumstances such as
poor blood flow to the kidneys,
infections, injuries, etc. the kidneys fail
to perform their functions. In such
situations, artificial kidneys are used for
blood filtration and this process is called
dialysis.
 Other than the urinary
system, skin, lungs, and even
eyes helps in excreting
waste products in different
forms. Sweating is a mode
of excretion where water,
urea, and other salts are
excreted through the skin.
Lungs help us to exhale
gaseous wastes such as
carbon dioxide, nitrogen, etc.
 Other E xc re tory
O rg an s
1. Skin
The skin is a part of the integumentary system, however it
additionally performs a role in excretion via the
production of sweat through sweat glands in the dermis.
Although the primary role of sweat production is to chill
the body and hold temperature homeostasis, sweating
additionally gets rid of extra water and salts, as well as
a small quantity of urea.
1.
 2. Lungs
The lungs are a part of the respiratory system, however
they're additionally vital organs of excretion. They are
accountable for the excretion of gaseous wastes. The
primary waste gas excreted through the lungs is carbon
dioxide, that's a waste product of cellular respiration in
cells. Carbon dioxide is subtle from the blood into the air
in the small air sacs called alveoli.
By expelling CO2 from the blood, the lungs assist maintain
acid-base homeostasis. In fact, it's the pH of blood that
controls the breathing rate. Water vapour is lifted up
from the lungs and different organs of the breathing
tract because the exhaled air passes over their wet
linings, and the water vapour is excreted together with
the carbon dioxide.
 3
LIVER

The liver has various fundamental functions, which include

secreting bile , storing glycogen, synthesising many proteins and
different compounds, and secreting endocrine hormones.
Additionally, the liver is a completely vital organ of excretion.
The liver breaks down many materials in the blood, along with
toxins. For example, the liver transforms ammonia into urea,
which is filtered from the blood through the kidneys and
excreted in urine.
 CONCLUSION

The excretory system is very vital for the

existence of an organism. The food that we take
needs to be removed as well, and it would be
possible only with the help of the excretory
system. Not only does it help remove metabolic
wastes from the body, regulate blood pressure,
and maintain the electrolyte balance in the
body. Organs like skin also help in the removal
of wastes from the body in the form of sweat. In
this process, the salts and urea are excreted
from the body. Lungs and liver are also included
in the secondary excretory system organs list.
 CASE STUDY 1
Title: A Case Study on the Excretory System: Mr. Smith's Kidney
Stones

Introduction:
The excretory system is a vital component of the human body
responsible for filtering waste products and maintaining the
body's internal environment. This case study examines the
condition of Mr. John Smith, a 45-year-old man, who
experienced kidney stones, a common disorder of the excretory
system.

Patient Background:
Mr. John Smith is a 45-year-old male with a history of occasional
back pain and urinary tract infections. He has a family history of
kidney stones, which increases his susceptibility to the
condition. Mr. Smith's lifestyle includes a diet high in oxalate-
rich foods, limited water intake, and occasional alcohol
consumption. These factors contribute to his increased risk of
kidney stone formation.
 Presenting Symptoms:
Mr. Smith presented to the emergency room with severe,
colicky right-sided flank pain that radiated to his lower
abdomen and groin. He also experienced nausea and vomiting,
which prompted him to seek medical attention. His initial
assessment revealed tenderness in the right costovertebral
angle and microscopic hematuria (blood in urine).

Diagnostic Investigations:
1. Urinalysis: Presence of red blood cells and white blood cells
in urine, along with crystals.
2. Imaging: Abdominal X-ray and computed tomography (CT)
scan revealed the presence of kidney stones, specifically
calcium oxalate stones measuring approximately 1.5 cm in
diameter in the right kidney.

Diagnosis:
Based on the clinical presentation and diagnostic findings, Mr.
Smith was diagnosed with nephrolithiasis, commonly known as
kidney stones. In his case, calcium oxalate stones were the
primary culprits.
 Pathophysiology:
Kidney stones are solid mineral deposits that form in the
kidneys. In Mr. Smith's case, calcium oxalate stones formed
due to a combination of factors:
- High dietary intake of oxalate-rich foods.
- Insufficient fluid intake leading to concentrated urine.
- Genetic predisposition due to a family history of kidney
stones.
- Occasional alcohol consumption, which can dehydrate the
body.

Treatment:
Mr. Smith's treatment plan involved a combination of
medical and dietary interventions:
1. Hydration: Mr. Smith was instructed to increase his fluid
intake significantly to dilute his urine and prevent stone
formation.
2. Pain Management: He received analgesics to manage the
severe pain associated with kidney stones.
3. Medications: Depending on stone composition and size,
medications to facilitate stone passage or promote
dissolution may be prescribed.
4. Dietary Modifications: Mr. Smith was advised to reduce his
consumption of oxalate-rich foods and maintain a balanced
diet.
5. Follow-up: Regular monitoring and follow-up appointments
with a urologist to assess stone progression and overall kidney
health.

Outcome:
With appropriate medical treatment and lifestyle changes, Mr.
Smith successfully passed the kidney stones naturally within a
few weeks. Follow-up imaging confirmed the absence of
residual stones. He continued to maintain a healthy diet and
adequate hydration to prevent future stone formation.

Conclusion:
This case study highlights the importance of the excretory
system in maintaining internal homeostasis and the role it
plays in conditions such as kidney stones. By addressing risk
factors, implementing dietary modifications, and receiving
appropriate medical care, Mr. Smith's excretory system was
able to eliminate the kidney stones and restore his health. It
also underscores the significance of lifestyle choices in
preventing excretory system disorders.
CASE STUDY 2
Title: A Case Study on the Excretory System: Mrs. Johnson's
Chronic Kidney Disease

Introduction:
The excretory system plays a crucial role in maintaining fluid
and electrolyte balance and eliminating waste products from
the body. This case study examines the condition of Mrs. Sarah
Johnson, a 65-year-old woman, who has been diagnosed with
chronic kidney disease (CKD), a progressive disorder of the
excretory system.

Patient Background:
Mrs. Sarah Johnson is a 65-year-old female with a history of
hypertension and type 2 diabetes. She has been taking
medications for these conditions for several years. Mrs.
Johnson's lifestyle includes a diet high in processed foods,
limited water intake, and a sedentary lifestyle. These factors
have contributed to her increased risk of developing CKD.
 Presenting Symptoms:
Mrs. Johnson presented to her primary care physician with
complaints of fatigue, swelling in her lower extremities, and
frequent nighttime urination. She also reported increased blood
pressure readings and decreased appetite. Physical examination
revealed edema (fluid retention) in her lower legs and elevated
blood pressure.

Diagnostic Investigations:
1. Blood Tests: Elevated serum creatinine and blood urea nitrogen
(BUN) levels, indicating impaired kidney function.
2. Urinalysis: Presence of proteinuria (excess protein in urine),
hematuria (blood in urine), and reduced glomerular filtration rate
(GFR).
3. Imaging: Renal ultrasound and Doppler studies to assess kidney
structure and blood flow.

Diagnosis:
Based on the clinical presentation and diagnostic findings, Mrs.
Johnson was diagnosed with stage 3 chronic kidney disease
(CKD), characterized by moderately impaired kidney function and
the presence of proteinuria.
 Pathophysiology:
Chronic kidney disease results from the progressive loss of kidney
function over time. In Mrs. Johnson's case, the following factors
contributed to CKD development:
- Long-standing hypertension and diabetes, both of which are risk
factors for kidney damage.
- A diet high in processed foods, which can contribute to high blood
pressure and kidney stress.
- Limited water intake, potentially leading to concentrated urine and
kidney damage.
- Sedentary lifestyle, which can exacerbate cardiovascular
conditions and impact kidney health.

Treatment:
Mrs. Johnson's treatment plan focused on managing her CKD and
preventing further deterioration:
1. Blood Pressure Control: Medications to control her blood pressure
were adjusted to target lower levels to protect her kidneys.
2. Diabetes Management: Tight glycemic control to prevent further
kidney damage.
3. Dietary Modifications: A renal-friendly diet that limits sodium,
protein, and phosphorus intake while promoting adequate fluid
intake.
4. Medications: Medications to manage symptoms, such as swelling
and anemia, and protect kidney function.
5. Lifestyle Changes: Encouragement to engage in regular physical
activity and maintain a healthy weight.

Outcome:
Mrs. Johnson's management plan aimed to slow the progression of
CKD and maintain her quality of life. While CKD is a chronic condition,
early intervention and adherence to treatment recommendations can
help slow the decline in kidney function. Mrs. Johnson continued to
receive regular follow-up care to monitor her kidney function, blood
pressure, and diabetes control.

Conclusion:
This case study highlights the significance of the excretory system
in maintaining overall health and the consequences of chronic
kidney disease. Early diagnosis and intervention, along with lifestyle
modifications, are essential in managing and potentially slowing the
progression of CKD. Mrs. Johnson's case underscores the
importance of addressing risk factors and making necessary
changes to protect kidney function and improve overall well-being.
 https://biologydictionary.net/excre
tory-system/

https://www.inspiritvr.com/general-
bio/human-biology/excretory-system-
study-guide

Bibliography
https://unacademy.com/content/upsc
/study-material/general-
science/excretory-system/

https://humanbiology.pressbooks.tru.
ca/chapter/18-2-organs-of-excretion/
THANK YOU!