<< Chapter < Page Chapter >> Page >
HCO 3 + H + H 2 CO 3 CO 2  + H 2 O MathType@MTEF@5@5@+=feaagyart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaeisaiaaboeacaqGpbWaaSbaaSqaaiaaiodacqGHsislaeqaaOGaae4kaiaabccacaqGibWaaWbaaSqabeaacaqGRaaaaOGaeyiLHSQaaeisamaaBaaaleaacaqGYaaabeaakiaaboeacaqGpbWaaSbaaSqaaiaabodaaeqaaOGaeyiLHSQaae4qaiaab+eadaWgaaWcbaGaaeOmaaqabaGccaqGGaGaae4kaiaabccacaqGibWaaSbaaSqaaiaabkdaaeqaaOGaae4taaaa@4C48@

The significant recovery of solutes from the PCT lumen to the interstitial space creates an osmotic gradient that promotes water recovery. As noted before, water moves through channels created by the aquaporin proteins. These proteins are found in all cells in varying amounts and help regulate water movement across membranes and through cells by creating a passageway across the hydrophobic lipid bilayer membrane. Changing the number of aquaporin proteins in membranes of the collecting ducts also helps to regulate the osmolarity of the blood. The movement of many positively charged ions also creates an electrochemical gradient. This charge promotes the movement of negative ions toward the interstitial spaces and the movement of positive ions toward the lumen.

Reabsorption of bicarbonate from the pct

This diagram shows the process of reabsorption of bicarbonate by the proximal collecting tubule.

Reabsorption and secretion in the loop of henle

The loop of Henle consists of two sections: thick and thin descending and thin and thick ascending sections. The loops of cortical nephrons do not extend into the renal medulla very far, if at all. Juxtamedullary nephrons have loops that extend variable distances, some very deep into the medulla. The descending and ascending portions of the loop are highly specialized to enable recovery of much of the Na + and water that were filtered by the glomerulus. As the forming urine moves through the loop, the osmolarity will change from isosmotic with blood (about 278–300 mOsmol/kg) to both a very hypertonic solution of about 1200 mOsmol/kg and a very hypotonic solution of about 100 mOsmol/kg. These changes are accomplished by osmosis in the descending limb and active transport in the ascending limb. Solutes and water recovered from these loops are returned to the circulation by way of the vasa recta.

Descending loop

The majority of the descending loop is comprised of simple squamous epithelial cells; to simplify the function of the loop, this discussion focuses on these cells. These membranes have permanent aquaporin channel proteins that allow unrestricted movement of water from the descending loop into the surrounding interstitium as osmolarity increases from about 300 mOsmol/kg to about 1200 mOsmol/kg. This increase results in reabsorption of up to 15 percent of the water entering the nephron. Modest amounts of urea, Na + , and other ions are also recovered here.

Most of the solutes that were filtered in the glomerulus have now been recovered along with a majority of water, about 82 percent. As the forming urine enters the ascending loop, major adjustments will be made to the concentration of solutes to create what you perceive as urine.

Ascending loop

The ascending loop is made of very short thin and longer thick portions. Once again, to simplify the function, this section only considers the thick portion. The thick portion is lined with simple cuboidal epithelium without a brush border. It is completely impermeable to water due to the absence of aquaporin proteins, but ions, mainly Na + , are actively pumped out of the loop by large quantities of the Na +/ K + ATPase pump. This has two significant effects: Removal of Na + while retaining water leads to a hypotonic filtrate by the time it reaches the DCT; pumping Na + into the interstitial space contributes to the hyperosmotic environment in the kidney medulla.

Questions & Answers

life circle of RBC and the life circle of WBC.
Yemi Reply
RBC 120days
Zeph
RBC 120days and WBC 10-12days
sai
what is anatomy?
Md Reply
positive feedback mechanism
Sirimala Reply
what is immunology
Riya Reply
immunology is a branch of medicine that study's the body immune system
SAMUEL
Immunology This is the study of specific and non-specific resistance of the body against infection i.e. the study of the immune response of a host to a foreign substance, which includes study of various reactions which are induced in the body by introduction of a substance.
Kaluki
what is role of elimination need like fluid and also stools
Munmun Reply
bone
Vijay
what is joint pain
Vijay
is the physical suffering caused by illness or injury of the joint
malulu
pls can someone describe shock,types ,pathophysiology and treatment
Isaac
this is what I'm thinking "After taking out everything the body needs, the bowel then expels the leftover waste."
isaiah
I think elimination also helps in the continuation of the digestive system because if the unwanted fluids and stools does not come out of the system it can create a problem in the digestive. system resulting in diseases.
Martha
shock is a condition whereby the circulating system is unable to get enough blood and oxygen to vital organs like the brain,heart,eye,kidney and others.
Martha
causing depression of those organs.
Martha
there are 2 classification of shock. primary shock: this occurs immediately after injury due emotional stimulus or pain.example hearing a bad news,sudden obstruction of airway.sudden heart attack. secondary shock :it occurs when primary shock is delayed
Martha
types of shock syncope (faint) oligaemic or hyppvovaemic shock. Anaphylactic shock. neurogenic/ physical shock septic sock catdiogenic shock.
Martha
What is the difference between dna duplication and chromosomes duplication?
to help you identify the human body parts to help you live a healthy life the study of Anatomy helps one to work in any health sector
sophia Reply
okay.
what is the function of the mitochondrial in the cell
Vida Reply
define and explain the synovial membrane
Mahmudu Reply
What is cloning?
Jesam Reply
relationship between anatomy and physiology
Ranjeeta Reply
anatomy is the structure and physiology is the function
Isaac
the branches of physiology
Asiedu Reply
is single DNA arranged into 46 chromosomes
Vaishnavi Reply
don't know about it
Sachin
no it is duble strand or pair of chromosomes
Marta
how does muscle contraction work?
Matthew
no,it is arranged as 23 pairs chromosomes
Ajiola
what are the parts of a cell?
Noel Reply
cell body, nucleus, cytoplasm, endoplasmic reticulum (rough and smooth), Golgi apparatus, cell membrane and organelles.
Heather
cell membrane, cell wall,cytoplasm, nucleus, etc
Felix
explain how skeletal muscles work
Felix
they work voluntarily
Trina
46 chromosomes present in which part of human body
Anar
when twins born how both of them carry 46 chromosomes
Anar
In the nuclear membrane
wisdom
but thiere r many cells n definetely cells have many nuclear membrane
Anar
cytoplasm plasma membrane nucleus
Ajiola
nucleus cytoplasm epr spr mitochondria
sureshbabu
cell have many parts and it act as different function s
sureshbabu
lysosome, golge body, cytoplasm, smooth endoplasmic reticulum
Vida
what is sex with male and female!
Muhammad Reply
intercourse
Jessie
sexual intercourse
Jessie
for formation of new generation
Sunil
sex is a female and male body courtship, rubbing of penis and vagina which results in release of fluids (sperm) from male in to the vagina of the female know as ejaculation
CHUOL
sex is a body courtship, penis and vagina rubbing which results in release of fluids sperm)
CHUOL
how sure a u?
Pius
it's like copulation
Pius

Get the best Anatomy & Physiology course in your pocket!





Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Anatomy & Physiology' conversation and receive update notifications?

Ask