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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

plzzz explain cardiac cycle
Piya Reply
what is anatomy
Gifty Reply
is the study of body structure
Amos
What are some of first questions are expected in anatomy and physiology course
Milner Reply
what is pacemaker
mekfira
its a device that is put into the heart to make sure it beats properly
Michelle
SA node produces impulse is called pacemaker
Piya
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Khubaib
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Hayat
hi everyone
Hong
hey
Edrick
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Damien
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Damien
hlo
Lost
which of the following is the epithelial tissue that lines the interior of blood vessels?
Firomsa Reply
endothelial tissues
Osaki
Endothelial tissue
mabast
why are the questions only 3
Chisom Reply
you too can ask
Addo
what is the treatment of herpes simplex virus?
riad Reply
the long bone with two primary center's of ossification for shaft is ________
Aarambam
medulla
Addo
good
Ravi
ha moj ha
Hani
doctor and nurse
Ravi
y 're the questions only 3
Chisom
women are much likely to be pregnant at which stage?
Fatoumatta Reply
There are only six days during any cycle when a woman can get pregnant - the five days leading up to ovulation and the 24 hours after ovulation. This is because sperm can live for up to 5 days in a woman's body, and the ovum lives for only 12-24 hours.
THE
right
Adil
does this apply to women close to menopose
Kuria
what's reason the reason for BP growing ?
Adil
when after they have intercourse
AJ
what is andropause
William Reply
It's the men version of menopause!
Catia
The testosterone levels decrease
Catia
what would happen if the sugar lever drops below the normal level
Marvin Reply
If our blood sugar drops below 70 mg/dL, we may have symptoms, such as feeling tired, weak, or shaky, become confused or drowsy or even lose consciousness and possibly die.
Dhanya
symptoms of hypoglycemia include: shakiness, dizziness, headache, confusion, rapid pulse rate, sweating, Hunger, etc.
EMERIBE
you right
Khubaib
You become dizzy and weak
evans
Is there any way to disable this chat feature or at least mute notifications? Also, does every textbook app from this creator have the chat function?
Atone Reply
I don't think you can disable chat and yes it is on every app
AJ
what is homeostasis
Nikky Reply
what is respiratory
Nikky
Respiratory is breathing
Atone
respiration is an exchange of gases (O2 & CO2) between the body and outside environment.
joey
homeostasis is internal balance.
Ali
Respiratory is system where the body takes in oxygen n releases carbondioxide
Hassan
respiratory system is a system where exhalation and inhalation takes place
Kom
1)inhalation: active diaphragm & external intercoastal muscles 2)exhalation: passive (allow muscle group to relax)
Shoukat
mantaince of body is called homeostasis
Komal
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Khubaib
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Komal
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Rinku
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Rinku
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Khubaib
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SARFARAJ
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Khubaib
answer me please...What is basic concept or Acidosis?
Khalid
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SARFARAJ
al hamd.o.lillah muslim
Khubaib
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Khubaib
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SARFARAJ
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Khubaib
myself Khalid Shabbir.Doctor of Anesthesia from PIMS Hospital.& belongs to Capital IslamAbad(Pakistan).
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Khubaib
tell me abt ethmoid bone
Sakshi
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SARFARAJ
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SARFARAJ
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Khubaib
m gd..plz tell me the answer of it..
Sakshi
Face ki he ethmoid bone
Rakesh
ethmoid bone. Irregularly shaped bone anterior to the solenoid. Forms the roof of the nasal cavity, upper nasal septum, and part of the medial orbit walls.
LaKecia
Its unpaired bone of skull that saprate the nasal cavity from the brain it's located at the roof of the nose between the two orbits it's bone is one of the bones that make up the orbit of eye.
SARFARAJ
sphenoid I meant
LaKecia
wrist joint ka dusra name kya he
Rakesh
till me fast my ans
Rakesh
Also included in the ethmoid bone is the crista galli and the cribriform plates. The plates help form the roof of the nasal cavity and the floor of the anterior cranial fossa.
LaKecia
the outer most covering of the brain ( the dura mater) attached to the crista galli and helps secure the brain in the cranial cavity
LaKecia
Sakshi Mishra. I hope that helped!
LaKecia
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Sakshi
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Sakshi
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LaKecia
ye kya
Dr
hi
Dr
oh welcome sakshi
Khubaib
synovial joint will have present in wrist
sk
what's the smallest blood vessal in the body?
sk
respiration is the process of inspiration an expiration
Bel
first fall give me ans plz
sk
The protection of internal envirnment from the harm of external envirnmen is called as homeostasis.
Rana
Because stem cells have the unique ability to develop into any cell, stem cell therapy is being considered for treatment of kidney damage. What are your thoughts on stem cell treatment? Give at least three reasons for or against the treatment.
Samira Reply
to know the structure of the human body. to study the region of the human body. to understand the circulation of blood in the human body.
Angelashimakela Reply
what do CNS stand for
Angelashimakela Reply
central nervous system
Dustin
What does that mean
Shafiw
what does what mean
Larita
It means the system of brain and spinal cord! Sensory system of body!
rashid
is it where we find sensory gland?
Angelashimakela
glands are not a part of CNS! but sensory receptors are a part of peripheral nervous system!
rashid
PNS
rashid
👏
Angelashimakela
Ask what u want to?
rashid
structure, function and results
Dustin Reply

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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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