The document discusses the human excretory system. It outlines the major functions of the urinary system as removing waste and regulating fluid balance. It then traces the path of urine formation from the nephrons in the kidneys through the ureters to the bladder and out the urethra. Key concepts covered include glomerular filtration, tubular reabsorption and secretion, and the roles of hormones like aldosterone and ADH in controlling fluid balance. Common disorders of the urinary system like kidney stones and bladder infections are also mentioned.

1. The
Excretory
System
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2. Essential Questions/Learning Outcomes
 List four major functions of the urinary system.
 Trace the path of urine from its formation to its exit from the body.
 Compare and contrast the structure and functions of the male
versus female urethra
 label the structure of a nephron.
 Distinguish between glomerular filtration, tubular reabsorption, and
tubular secretion.
 Discuss where the reabsorption of salt occurs and how it is
hormonally controlled.
 Describe two ways that the kidneys regulate blood pH .
 Indicate how damage to the glomeruli/nephrons can lead to uremia
and edema.
 Describe three common disorders of the bladder and urethra.
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3. Vocabulary
 Cortex
 Osmoregulation
 Medulla
 Nitrogen waste
 Pelvis
 Urea
 Nephron
 Urine
 Bowman’s Capsule
 Ureter
 Glomerulus
 Urethra
 Loop of Henle
 Urinary bladder
 Collecting Duct
 Kidney
 Pore
 Renal vein and artery
 Sebaceous Gland
 Pacinian Corpuscle
 Melanocyte
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4. Osmoregulation
 Regulation of Body Fluids and Salt Levels.
 How do different animals control the
amount of water in their bodies?
– Amoeba, and Paramecium use contractile
vacuoles
– Fish
– Humans use their kidneys
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5. Excretion
 What is excretion?
– The removal of metabolic wastes from the organism
 What are the main metabolic wastes in living
organisms?
– Carbon Dioxide
– Water
– Urea – a nitrogenous waste – from amino acids
– Ammonia – nitrogen waste
– Mineral Salts
– Creatinine – from muscle metabolism!!
– Uric Acid – from nucleic acid
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6. Nitrogenous
Wastes
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7. Excretory Organs
 What organs remove nitrogenous wastes?
– Protists – diffusion
– Planaria
– Insect
– Fish excrete through gills
– Marine birds need to excrete excess salt
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9. Human Excretory System
 What are the main human excretory
organs?
– Lungs
– Liver
– Sweat Glands
– Kidneys
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10. Lungs and Liver
 Disposal of hemoglobin
 Remove carbon dioxide
when old red blood cells are
and water.
destroyed…form bile
pigments.
 Compounds containing
nitrogen break down to
from urea…go to kidney.
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11. The Human Urinary System
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12. Urinary Tract
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13. The Kidney - overview
 Bean shaped organ
 10cm long
 found against the muscles of the back
below the diaphragm
 Functions:
– Remove the waste of cellular metabolism from
the blood to produce URINE
– Control the concentration of some substances.
HOW KIDNEY'S WORK
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15. 1. Cortex
 Filtering of
the Blood
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16. Filtering Unit in the Cortex:
Nephron!!!!
NEPHRON – each kidney about 1.25 million nephron
Parts to the Nephron:
– Bowman’s Capsule – double walled cup structure
– Glomerulus – cluster of blood capillaries
– Proximal Convoluted Tubule – most reabsorption and
secretion
– Loop of Henle –(in medulla) tubule that winds and twists
before emptying filtrate into a collecting duct. Water
Reapsorption…..
– Distal Convoluted Tubule – “filtrate fine-tuning.”
Specialized reabsorption and secretion controlled by the
hormone ALDOSTERONE! ( Adrenal Gland)
– Collecting Duct – can receive filtrate from several
nephrons. Final regulated water reabsorption. Controlled
by the hormone ADH!! (Pituitary Gland)
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17. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
nephrons
Fig. 16.3b
renal
collecting cortex
duct
renal
medulla
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cottingham

18. Nephron
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20. 2. Medulla
contain the Loop
of Henle and
collecting ducts;
carry urine to
the….
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21. 3. Pelvis
 Drains urine into
the URETER…
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23. Formation of Urine! – Filtration
The Mammalian Kidney - HOW KIDNEY
1. Filtration – occurs in the GLOMERULUS.
– Blood is placed under pressure.
– Pressure forces water, salts, urea, glucose and
amino acids OUT of the blood and…..
 Into the BOWMAN’S CAPSULE.
 Blood cells and blood proteins are too
large to pass through.
 Urine(filtrate) passes through tubule into
the collecting duct.
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24. Formation of Urine - Reabsorption
 Reduces volume of filtrate
 Occurs in the tubules and collecting duct.
 Returns important substances to blood
 99% of water(osmosis)
 glucose(act. Transport)
 amino acids(A.T.)
 some salt ions(A.T.)
 Potassium ions (A.T.)
 If there is too much of a particular
substance, it reaches the Kidney Threshold
Level – if the concentration reaches a
certain level, the excess is not reabsorbed.
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25. Formation of Urine - Secretion
 Takes substances out of the blood and
add them to the filtrate! Selective Process.
 Creatinine is secreted!
 Ions, drugs, toxins secreted!
 BY REABSORPTION AND SECRETION,
THE FILTRATE IS CHANGED AS IT
TRAVELS THRU THE NEPHRON.
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26. Hormones and Excretion
 Aldosterone
 Regulates Na and K excretion
 Presence of hormone stimulates secretion of K and
reabsorption of Na.
 Helps to maintain proper blood pressure.
– High Salt Level Raises Blood pressure
 Helps to control blood pH levels – secretion of H+
into tubules.
 Released due to high K levels.
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29. Hormones and Excretion
ADH (Antidiuretic Hormone)
 Released by pituitary gland in response to
signal from the hypothalamus(brain).
 Responsible for final reabsorption of water
 In collecting duct.
– Lower levels of water: release of ADH into
blood.
– ADH causes the cell membranes in collecting
duct to become permeable to water.
– Process reverses when water level is restored.
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30. Urinary Tract
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31. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Fig. 16.1
1. Kidneys produce
renal artery urine.
renal vein
aorta
2. Ureters transport
inferior vena cava urine.
3. Urinary bladder
stores urine.
4. Urethra passes
urine to outside.
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32. Other Urinary System Organs
 Renal Artery – blood enters the
kidney
 Renal Vein – Blood leaves the kidney
 Ureter – connects kidney to Bladder
 Urinary bladder – Stores urine
 Urethra – tube leading out of the
body
– Part of the penis in men
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33. Skin (Integumentary)
SWEAT GLANDS:
 Small, coiled, tubular
glands.
 Found in the dermis
 Contain ducts which lead
to the epidermis: pores.
 Blood capillaries near
gland.
 Water, Salt, nitrogenous
waste diffuse from blood
into the gland.
 TEMPERATURE
REGULATION
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34. Other Skin Parts
 Epidermis – outer
water proof layer
 Dermis – contains all
skin parts:
– Blood vessels
– Sebaceous glands
– Pacinian Corpuscles
– Melanocytes
– Hair follicle
 Hypodermis – contains
subcutaneous fat
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35. Diseases of the Excretory System
Kidney Stones –
 Cause - metabolic
disorder… calcium,
proteins and uric acid
the build up of these
substances into a
large deposit (stone)
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36. Cirrhosis
 Liver - excessive
intake of alcohol over
a extended period of
time which causes an
impairment of liver
functions.
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37. Bladder Infection
infection of the urinary
tract
 burning sensation in the
that can move down
from the middle of the
back towards the front of
the groin, burning
sensation while urinating
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38. Dialysis
 Artificial filtering of
blood.
 the process of
cleaning wastes from
the blood artificially
with special
equipment.
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39. Kidney Transplant
 Kidney Transplant Animation
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