Download Chapter 9 The Kidneys and Excretion

The Kidneys
and excretion
http://www.kidney.org/kidneydis
ease/kidneyquiz.cfm#
Kidney Quiz
Crash Course –
The Excretory System: From
Your Heart to the Toilet
http://www.youtube.com/watch?
v=WtrYotjYvtU
Introduction:
human body cells produce enormous
amounts of waste such as carbon dioxide,
ammonia and urea
our bodies provide several ways to get rid of
(or excrete) cellular wastes, they are: the
lungs, the skin, the liver, the kidneys and the
large intestine
the kidney ranks as one of the most important
because it rids the body of a variety of
dissolved wastes, and also plays a role in
regulating the chemical constancy of the
bloodstream
The role of the liver in excretion
the liver plays a role in transforming material into
removable waste
alcohol and heavy metals are changed by the liver into
soluble units which can be removed by the kidney
proteins are converted into carbohydrates through the
process of deamination
deamination is the removal of the nitrogen-containing
amino group in proteins forming ammonia
in the liver, two molecules of ammonia combine with
carbon dioxide to form urea
NH3 + NH3  urea
uric acid is produced by the liver from the breakdown of
amino acids
http://www.gdn.edu/Faculty/pjen/Anatomy%20and%20physiology%202210K%20-%20lecture%205%20notes.htm
The Urinary System
The urinary system
plays a significant
role in:
Removing waste
Balancing blood pH
Maintaining water
balance
http://www.health.uab.edu/Print.aspx?pid=15557&print=yes
https://www.youtube.com/watch?v=2_
7Q1xQ-NWU
Parts of the Urinary System
Kidneys:
each kidney is about the size of a fist, lies on
either side of the vertebral column
located high on the abdominal wall beneath
the diaphragm and the lungs
help to eliminate wastes from the blood
help to regulate water concentration of the
body as well as blood pressure
helps to maintain a constant pH
Parts of the Urinary System
Ureters:
carry the wastes filtered from the blood in the
kidneys to the urinary bladder
Urinary Bladder:
stores urine
stretch receptors signal to the brain when it is
time to empty the bladder (a stimulus
strongest when there are more stretch
receptors stimulated)
Parts of the Urinary System
Urethra:
a tube that carries urine from the bladder to
the exterior of the body
Longer in men than in women (why are women
more prone to Urinary Tract Infections?)
Aorta:
an artery that carries oxygenated blood from
the heart to the kidneys
Inferior Vena Cava:
a vein that carries deoxygenated blood to the
heart from the kidney
Urination
when there is about 200 mL of urine in
the bladder, the message to urinate is
sent. At about 600 mL, voluntary
control is lost
a sphincter muscle a the base of the
bladder controls urination
Parts of the Kidney
http://www.biologycorner.com/bio3/notes-urinary.html
Parts of the Kidney
Cortex:
an outer layer of connective tissue that surrounds
the kidney
Medulla:
the inner layer of the kidney, found beneath the
cortex
Renal Pelvis:
the center chamber of each kidney that connects
to the ureters
urine produced drains into the renal pelvis and
drains into the ureters
Parts of the Kidney
Renal Vein:
veins that branch from the kidney to the inferior
vena cava
carry deoxygenated blood to the heart
Renal Artery :
arteries that branch into the kidneys from the aorta
carry oxygenated blood from the heart
Nephrons :
the functional unit of the kidney (approx. 500, 000
per kidney)
the site of blood filtration
Anthony Atala: Growing
new organs
http://www.ted.com/talks/anthony_atal
a_growing_organs_engineering_tissue.
html
Parts of the Nephron
Afferent arteriole:
branches from the renal artery and carries blood to the
glomerulus
Efferent arteriole:
carries blood away from the glomerulus
Glomerulus:
a tuft of capillaries that is surrounded by the Bowman’s
capsule
the site of filtration
Bowman’s capsule
a cup-like structure that surrounds the glomerulus
receives filtered fluids (wastes) from the glomerulus
Parts of the Nephron
www.colorado.edu/.../IPHY3430-200/13urinar.html
http://www.handwrittentutorials.com/vi
deos.php?id=73
Nephron anatomy
Parts of the Nephron
Proximal tubule:
joins the Bowman’ s capsule with the Loop of Henle
the site of reabsorption from the nephron back into the blood
Distal tubule :
the last segment of the nephron
connects the Loop of Henle to the collecting duct
reabsorption can occur here
Loop of Henle:
takes urine from the proximal tubule to the distal tubule
descending Loop of Henle is permeable to water and ions and is
the site of some reabsorption
ascending Loop of Henle is impermeable to water so sodium ions
are actively transported out
Collecting duct:
collect urine from many nephrons and carries the urine to the renal
pelvis
http://www.youtube.com/watch?v=cc8s
Uv2SuaY
Khan Academy
Formation of Urine
Four processes are crucial for the
formation of urine
Glomerular filtration
Tubular reabsorption
Tubular secretion
Water reabsorption
http://www.biologymad.com/resources/kid
ney.swf
Formation of Urine
Glomerular Filtration
Water and some dissolved substances are forced
from the glomerulus into the Bowman’s capsule
The pores of the capillaries are large enough to allow for
water and some ions to pass but small enough to prevent
proteins and blood cells to pass through
The force required for this filtration is provided by
extremely high blood pressure (four times greater
than anywhere else in the body)
Each day, 1600-2000 L of blood passes through
the glomerulus, producing approx. 180 L of
glomerular filtrate
Formation of Urine
Tubular Reabsorption in the proximal tubule
The process where ions, glucose and water are
reabsorbed into the blood in the proximal tubule
The cells of the proximal tubule have many
mitochondria
Mitochondria are required to produce the ATP required
for the active transport of sodium ions, glucose and other
solutes back into the blood
Negatively charged ions passively follow the positive ions
attracted to their positive charge
Water follows the ions by osmosis
Formation of Urine
Tubular Reabsorption and Secretion in the
Distal Tubule
Active transport of sodium ions from the filtrate
into the capillaries occurs here
Negative ions such as chloride follow passively by
charge attraction
There is also passive reabsorption of water by
osmosis
Potassium and hydrogen ions are actively
secreted into the distal tubule
Nitrogen containing wastes, other minerals and
some drugs are also secreted into the distal tubule
(if they aren’t already in there)
http://faculty.southwest.tn.edu/rburkett/A&P2%20urinary_system.htm
Formation of Urine
Reabsorption of Water from the collecting
duct
The concentration of ions as they travel down
the collecting duct increases
This causes passive diffusion of water from the
filtrate back to the blood by osmosis
The reabsorption of water causes the filtrate
to become more concentrated – it is called
urine
Formation of Urine
http://www.mhhe.com/biosci/ap/dynamichuman2/content/urinary/visuals.mhtml
http://www.handwrittentutorials.com/vi
deos.php?id=75
Water Balance in the Body
the kidneys are involved in regulating
body fluid levels
adjustments in water absorption of the
kidney involves interaction with the
body’s nervous and endocrine
systems
Water Balance in the Body
Osmoreceptors in the hypothalamus are cells
that are sensitive to osmotic pressure
When blood plasma becomes too concentrated
(dehydration) osmotic pressure increases
Osmoreceptors send a message to the pituitary
gland to release a hormone called ADH (antidiuretic hormone)
ADH increases the permeability of the distal tubule
and collecting duct allowing more water to be
absorbed
This dilutes the blood and lowers osmotic pressure
Produces a more concentrated urine
Water Balance in the Body
When blood plasma is too dilute (low
osmotic pressure) osmoreceptors stop the
release of ADH
The distal tubule and collecting duct become
less permeable to water
More water is excreted in the urine and the
blood becomes more concentrated
The osmotic pressure of the plasma and
tissue fluids rises to normal
http://www.creationofman.net/chapter3/chapter3_5.html
Low amounts of ADH
ADH Present
Water Balance in the Body
Alcohol and caffeine act as diuretics
They decrease the release of ADH
This decreases the permeability of the
collecting ducts and the distal tubule and
increases water loss through the urine
Can lead to dehydration
Balance of salt in the Body
The kidneys regulate salt balance by controlling
the excretion and reabsorption of various ions
Sodium concentration can fluctuate depending on the
diet of a person and the consumption of diuretic
beverages
A drop in sodium concentration in the blood is achieved
by a hormone called aldosterone
Aldosterone stimulates the distal tubule and collecting ducts to
reabsorb sodium into the blood
Reabsorption of sodium is followed by chloride ions and water
Aldosterone also stimulates the secretion of potassium
ions into the distal tubule if the concentration is too high
Kidneys and Blood Pressure
The release of aldosterone may also be stimulated
by a decrease in blood pressure
Decreased Blood
Pressure
Renin released
Angiotensinogen
Angiotensin
Blood Vessel
Constriction
Adrenal gland
secretes
aldosterone
Increase water
reabsorption in
kidney
http://www.merck.com/mmhe/print/sec03/ch022/ch022a.html
Kidneys and Blood Pressure
High blood pressure is one of the main reasons for
kidney failure
The blood vessels in the kidneys are very sensitive to
changes in blood pressure
If they become damaged, the amount of extra fluid and
wastes that the kidneys can filter will be reduced
The extra fluid accumulates in the body, increase blood
volume and cause further increases in blood pressure
This cycle can continue until kidney function is so
reduced symptoms become obvious
http://www.youtube.com/watch?v=tAmLbclSucQ&feature=related
Maintaining Blood pH
Blood pH stays at approx. 7.4 due to:
Acid-base buffer system maintaining pH by
adding or removing H+ ions
The kidneys will excrete H+ ions and absorb
HCO3- ions as needed to maintain normal blood
pH
If blood is too acidic, kidneys will excrete H+
and HCO3- is reabsorbed
If blood is too basic, kidneys will not excrete H+
and not reabsorb HCO3-
Review tutorial
https://www.youtube.com/watch?v
=U1m7egrEdk0
Kidney Disorders
Diabetes Mellitus
caused by an inadequate secretion of insulin from
islet cells in the pancreas. Without insulin, blood
sugar levels tend to rise and this excess sugar
remains in the nephron
this excess sugar provides osmotic pressure that draws
water into the nephron
large volumes of sweet urine is lost by people with
diabetes mellitus
http://www.youtube.com/watch?v=VLiTbb6MaEU&feature=related
Kidney Disorders
Diabetes Insipidus
caused by the destruction of the ADH
producing cells of the hypothalamus
Without ADH to regulate water reabsorption,
urine output increases and the individual must
drink a lot of fluids
http://www.youtube.com/watch?v=Qyo5T6zMl8Y
Kidney Disorders
Bright’s Disease (also called
glomerulonephritis or nephritis)
characterized by inflammation of the
nephrons
This affects the permeability of the nephron,
especially at the Bowman’s capsule, allowing
proteins and other large molecules to enter
when the proteins enter the nephron, there
is no way for them to get out and as a
result, water is taken in because of the
osmotic pressure created
Kidney Disorders
Kidney Stones
caused by precipitation of the mineral
solutes in the blood
the stones are either alkaline or acid stones
these stones can be lodged in the renal pelvis
or move into the ureter, tearing tissues on its
way to the bladder and the urethra
very painful to “pass a kidney stone”
Guinnes Medical Records – Kidney stones
http://www.youtube.com/watch?v=16ewFJiQtw&feature=related
Well Mr. Osborne, it may
not be kidney stones after
all.
http://avconline.avc.edu/faculty/slangjahr/tidbits.html
Kidney Disorders
http://www.youtube.com/watch?v=HR0oEsBIF5c&feature=related
http://www.youtube.com/watch?v=IQKQ4eoKfTg
Dialysis
Drug error kills 2 Alberta
hospital patients
CBC News Posted: Mar 19,
2004 1:51 PM ET Last
http://www.cbc.ca/news/canada/drugerror-kills-2-alberta-hospital-patients1.509798