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Conversion of angiotensin i to angiotensin ii

This diagram shows the pathway of action of the renin-aldosterone-angiotensin system. An arrow in the center of the image shows the sequence of events that take place, and branching off from this arrow are indications of where in the body these events take place.
The enzyme renin converts the pro-enzyme angiotensin I; the lung-derived enzyme ACE converts angiotensin I into active angiotensin II.

Proximal convoluted tubule (pct)

Filtered fluid collected by Bowman’s capsule enters into the PCT. It is called convoluted due to its tortuous path. Simple cuboidal cells form this tubule with prominent microvilli on the luminal surface, forming a brush border    . These microvilli create a large surface area to maximize the absorption and secretion of solutes (Na + , Cl , glucose, etc.), the most essential function of this portion of the nephron. These cells actively transport ions across their membranes, so they possess a high concentration of mitochondria in order to produce sufficient ATP.

Loop of henle

The descending and ascending portions of the loop of Henle (sometimes referred to as the nephron loop) are, of course, just continuations of the same tubule. They run adjacent and parallel to each other after having made a hairpin turn at the deepest point of their descent. The descending loop of Henle consists of an initial short, thick portion and long, thin portion, whereas the ascending loop consists of an initial short, thin portion followed by a long, thick portion. The descending thick portion consists of simple cuboidal epithelium similar to that of the PCT. The descending and ascending thin portions consists of simple squamous epithelium. As you will see later, these are important differences, since different portions of the loop have different permeabilities for solutes and water. The ascending thick portion consists of simple cuboidal epithelium similar to the DCT.

Distal convoluted tubule (dct)

The DCT, like the PCT, is very tortuous and formed by simple cuboidal epithelium, but it is shorter than the PCT. These cells are not as active as those in the PCT; thus, there are fewer microvilli on the apical surface. However, these cells must also pump ions against their concentration gradient, so you will find of large numbers of mitochondria, although fewer than in the PCT.

Collecting ducts

The collecting ducts are continuous with the nephron but not technically part of it. In fact, each duct collects filtrate from several nephrons for final modification. Collecting ducts merge as they descend deeper in the medulla to form about 30 terminal ducts, which empty at a papilla. They are lined with simple squamous epithelium with receptors for ADH. When stimulated by ADH, these cells will insert aquaporin    channel proteins into their membranes, which as their name suggests, allow water to pass from the duct lumen through the cells and into the interstitial spaces to be recovered by the vasa recta. This process allows for the recovery of large amounts of water from the filtrate back into the blood. In the absence of ADH, these channels are not inserted, resulting in the excretion of water in the form of dilute urine. Most, if not all, cells of the body contain aquaporin molecules, whose channels are so small that only water can pass. At least 10 types of aquaporins are known in humans, and six of those are found in the kidney. The function of all aquaporins is to allow the movement of water across the lipid-rich, hydrophobic cell membrane ( [link] ).

Aquaporin water channel

This figure shows an aquaporin water channel in the bilayer membrane with water molecules passing through.
Positive charges inside the channel prevent the leakage of electrolytes across the cell membrane, while allowing water to move due to osmosis.

Chapter review

The functional unit of the kidney, the nephron, consists of the renal corpuscle, PCT, loop of Henle, and DCT. Cortical nephrons have short loops of Henle, whereas juxtamedullary nephrons have long loops of Henle extending into the medulla. About 15 percent of nephrons are juxtamedullary. The glomerulus is a capillary bed that filters blood principally based on particle size. The filtrate is captured by Bowman’s capsule and directed to the PCT. A filtration membrane is formed by the fused basement membranes of the podocytes and the capillary endothelial cells that they embrace. Contractile mesangial cells further perform a role in regulating the rate at which the blood is filtered. Specialized cells in the JGA produce paracrine signals to regulate blood flow and filtration rates of the glomerulus. Other JGA cells produce the enzyme renin, which plays a central role in blood pressure regulation. The filtrate enters the PCT where absorption and secretion of several substances occur. The descending and ascending limbs of the loop of Henle consist of thick and thin segments. Absorption and secretion continue in the DCT but to a lesser extent than in the PCT. Each collecting duct collects forming urine from several nephrons and responds to the posterior pituitary hormone ADH by inserting aquaporin water channels into the cell membrane to fine tune water recovery.

Questions & Answers

knuckle of the middle finger
James Reply
because of the gases (nitrogen, oxygen)
Nejat
why the heart is protected with that sac
Joshua Reply
To prevent collision with the lungs, lubricates the heart, protects the heart from infection in the event a peripheral organ is effected, and stabilizes the heart within the mediastinum.
Jeremiah
This app should be updated too much as there is very little information for some topics.I hope you will consider my information....
aman Reply
adenohypophysis is made up of what type of cells and what is the name of those cells?
Mannu Reply
whatpassesthroughmaleovale
armstrong Reply
motor root of the trigeminal nerve
Vandana
what is the nervous system about
Joshua
what passes through foramen ovale?
Farah Reply
what are the organelles of a cell
Amina Reply
muscular system
Vandana
nucleus ribosome Golgi body call membrane cytoplasm
Sabina
these are the cellular components that functions to provide energy,remove waste and cell division
Waziri
Organelles of the cell are: Mitochondria,Ribosome,golgi apparatus, nucleus, secretory granules, nuclear e t c
Khadijah
what are local hormones
Richard
Local hormones are hormones that effect the cell that released them or cells near the releasing cell and they do not circulate within the blood stream.
Jeremiah
the trachea bifurcated into how many branches on the right lung
barbie
three lobes
Richard
Explain the normal flow of blood.
Shikha
how can we maintain the internal living things
Choolwe Reply
how many seconds does a human will stop if you sneeze
Kharl Reply
idk
Erika
1 sec not specific
Jane
1_3seconds
Mannu
physiology of vision
Sudipta Reply
Can pure water become gel like?
ovie Reply
No
Abdulazeez
what is Homeostasis
Laura Reply
It is the ability of an organism to co ordinate it's internal environment so as to achieve balance in all areas
ovie
what is anatomy
Sandra Reply
what is physiology
Sandra
The study of how the body works
Joseph
the branch of biology dealing with the functions and activities of leaving organisms and their parts including all physical and chemical processes
Maria
the study of human body . phicically and chemically it's called anotomy physiology
Raj
the branch of biology dealing with the functions and activities of living organisms
Salman
which vein do we inject to give infusions
Belinda
it is the scientific study of the body structure
Choolwe
What Choolwe Muselitata said is the definition of anatomy
KWAKU
Physiology can also be described as the way in which a living organism or bodily part functions
KWAKU
Anotomy is the science which we humen body of structure and function know as the anotomy
Aman
study of the body funtion and structure
Kaoum
functional study of the body
Mosele
it is the study about the functions of body organs
Mannu
what are the vital sign procedure
jeniffer Reply
You start the TPR then BP after explaining the procedure to the patient and your requirements ready.
Dauda
which type of vein to you inject to give infusions?
Belinda
*do
Belinda
how long do u take radial pulse
Flavian Reply
1 minute
Mannu
You can take it for 15 seconds , the number you got you multiply wth 2
Likius
but in the aspect of the multiplying that isn't right
Sabina
radial pulse kya hai?
OM
?
OM
for more accurate values you must do the 1 minute
Jane
1 minute.
Andrew
60 seconds
Richard
1 minute
Kaoum
yes @sabina
Mannu

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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