Transcript Hormonal Control of Urine

DO NOW 4/21/15
Where does the filtration of water and
dissolved solutes occur in the kidney?
Why is water able to be diffused out of the
filtrate flowing through the PCT with no
addition of energy?
What are the 3 stages of urine formation?
UPCOMING DATES
 Tuesday, 4/7: Blood Quiz Corrections due
 Thursday, 4/9: Blood, Immune/Lymphatic BIG
Quiz
 Monday/Tuesday (PM), 4/13-14: Big Quiz
Corrections
 Friday, 4/17: Digestive Quiz
 Thursday, 4/23: Digestive Project due
 Monday, 4/27: Urinary Quiz; Urinary Project due
 Friday, 5/1: Urinary & Reproductive Test
 Thursday, 5/7: Semester 2 Final Exam
HORMONAL CONTROL
OF URINE
OBJECTIVE
 By the end of today’s class, I will be able to …
Describe how the kidney retains a high
concentration of solutes in the renal
medulla
Describe how the urinary system is
regulated by hormones
Describe urine storage and the process
of micturition
THE RENAL CORTEX VS. MEDULLA
Renal cortex:
 Renal corpuscle
 Renal tubules (PCT,
DCT)
Renal medulla
 Parts of the nephron
loop
 Collecting duct
RENAL CORTEX VS MEDULLA
The reabsorption we discussed
occurred in the PCT and DCT
The nephron loop does not have
these capabilities because it is too
thin to hold sodium pumps
THE DESCENDING LIMB OF THE NEPHRON
LOOP
The descending limb cannot have active
transport
For this reason only limited water will be
diffused out of the filtrate at this point
THE ASCENDING LIMBS
Both the ascending limb of the nephron
loop and the DCT do not allow water to
pass
The DCT does have sodium pumps and
actively pumps sodium into the space
around the DCT
If water cannot leave the ascending parts of the
nephron and salt can, what will the area around
the nephron loop be like in terms of salt and
solute concentration?
THE COUNTERCURRENT MECHANISM
Because the blood and filtrate pathways travel
down the renal medulla and then back up on a
parallel pathway, the amount of solute in the
kidney is kept very high.
THE COLLECTING DUCT
As the filtrate flows down the collecting duct
through the renal medulla, water can again be
reabsorbed.
The result is that urine is extremely
concentrated when leaving the kidney.
QUICK CHECK
What is different about the structure and
function of the nephron loop compared to the
PCT and DCT?
QUICK CHECK
Why is it very important that the
renal medulla have a very high
concentration of solute?
HORMONES
By the time the filtrate reaches the DCT,
about 90% of sodium and chloride and
80% of water which originally entered
the glomerular corpuscle have been
reabsorbed.
Reabsorption that occurs in the DCT is
then regulated by hormones to meet the
needs of the body.
3 KEY HORMONES
Aldosterone
Atrial Natriuretic Peptide
Antidiuretic Hormone
ALDOSTERONE
Produced in the adrenal cortex when blood
sodium levels are low
Aldosterone causes the DCT to absorb more
sodium and potassium
Water is also absorbed which increases the
amount of water in blood
This high volume of water in the blood
increases blood pressure
ATRIAL NATRIURETIC PEPTIDE
ANP is released in response to high
volumes of blood
ANP inhibits sodium absorption and
therefore decreases the amount of water
absorbed back into the blood
ANTIDIURETIC HORMONE
ADH is secreted by the pituitary gland
ADH is secreted when the concentration of
solutes in the blood is too high
When we are dehydrated, this concentration
increases
ADH allows water to be reabsorbed at a higher
rate in the collecting ducts by opening more
channels for water to diffuse.
QUICK CHECK
Does hormonal regulation occur in
the PCT or DCT?
QUICK CHECK
If a person has low sodium levels
in their blood, which hormone
will be secreted?
If the level of solutes in the blood
is too high, which hormone will
be secreted?
If there is too high of a volume of
blood flowing through the veins,
which hormone is secreted?
URINE STORAGE AND
EXCRETION
URINE PRODUCTION AND TRANSPORT
Kidneys produce
urine constantly,
but only release it
periodically.
Ureters transport
urine from the
kidney to the
urinary bladder for
storage
THE URINARY BLADDER
THE URINARY BLADDER
Hollow,
muscular
organ
Lies between
the pelvic floor
and the
peritoneum
THE URINARY BLADDER
The wall (detrusor)
is made of smooth
muscle
2 openings for
ureters and 1 for
urethra
URETHRA
Thin tube connecting bladder to
outside
2 sphincters help contain urine in
the bladder:
Internal Urethral Sphincter
External Urethral Sphincter
The primary difference between
male and female urethras is that
the male’s contains spongy
urethra
QUICK CHECK
How does urine get from the kidneys to
the bladder?
What is the bladder’s purpose?
What structure transports urine to the
outside of the body?
What is the wall of the bladder called?
TURN AND TALK
The respiratory system and the
urinary system both rid the body of
waste (carbon dioxide and urine,
respectively). Does the respiratory
system have a structure like the
bladder? Why or why not?
URINE EXCRETION
MICTURITION
The release of urine from the
bladder is called micturition.
Occurs by contracting the detrusor
and relaxing both sphincters
(internal and external)
INTERNAL AND EXTERNAL SPHINCTERS
The internal sphincter is controlled
by the autonomic nervous system
and will relax subconsciously
Will the external sphincter be
controlled by the same pathway?
STEPS TO MICTURITION
1.The bladder stretches as it
fills and sends signals to the
sacral portion of the spinal
cord.
STEPS TO MICTURITION
1.
The bladder stretches as it fills and sends signals to the
sacral portion of the spinal cord.
2.The sacral cord neurons “tell”
the detrusor to contract and
the internal sphincter to relax.
STEPS TO MICTURITION
1.
2.
The bladder stretches as it fills and sends signals to the
sacral portion of the spinal cord.
The sacral cord neurons “tell” the detrusor to contract and
the internal sphincter to relax.
3.The brain receives the sensory
message that the bladder is
full from the spinal cord.
STEPS TO MICTURITION
1.
2.
3.
The bladder stretches as it fills and sends signals to the sacral
portion of the spinal cord.
The sacral cord neurons “tell” the detrusor to contract and the
internal sphincter to relax.
The brain receives the sensory message that the bladder is full
from the spinal cord.
4. If the time is optimal for
urination, the brain sends a
signal to the external sphincter
to relax and then detrusor
contracts.
QUICK CHECK: PUT THESE IN ORDER
1. The spinal cord relays the message that the
bladder is full to the brain.
2. The brain tells the external sphincter to relax
3. The spinal cord tells the internal sphincter to
relax
4. The external sphincter relaxes and the
detrusor contracts
5. The bladder stretches and relays that signal to
the spinal cord
6. The detrusor contracts and the internal
sphincter relaxes
SO, THIS IS A THING…
IT’S STORY TIME!
Write a story for kids about potty
training.
You can choose any format you’d like
but it has to inform them about:
Kidneys, ureters, urethra, bladder, and
sphincters
How urine is created in the kidneys
The process of micturition (How your body
decides its time to use the restroom)