its the introduction about kidney function, glomerular filtrate, tubular reabsorption mechanism, in this slide u may able to clearly know about the basics.
if you want to know about the basic property of kisney nephron it is very easy yo obxerve
Importance of enzymes : The two aminotransferases that are checked are the alanine aminotransferase (ALT or SGPT) and aspartate aminotransferase (AST or SGOT). These liver enzymes form a major constituent of the liver cells. They are present in lesser concentration in the muscle cells.
This presentation includes information about secretion of glucagon, inhibitors, regulation of secretion, mechanism of action & actions of glucagon. It also includes ways to prevention of occurrence of hyperglycemia.
Lipid profile Plasma contains many lipids such as triglyceride acids under lipid profile serum total control cholesterol serum track is glyceride these parameters are included
Importance of enzymes : The two aminotransferases that are checked are the alanine aminotransferase (ALT or SGPT) and aspartate aminotransferase (AST or SGOT). These liver enzymes form a major constituent of the liver cells. They are present in lesser concentration in the muscle cells.
This presentation includes information about secretion of glucagon, inhibitors, regulation of secretion, mechanism of action & actions of glucagon. It also includes ways to prevention of occurrence of hyperglycemia.
Lipid profile Plasma contains many lipids such as triglyceride acids under lipid profile serum total control cholesterol serum track is glyceride these parameters are included
Thousands of metabolic processes in myriad body cells produce hundreds of waste products.
The urinary system removes them by filtering and cleansing the blood as it passes through the kidneys.
Another vital function is the regulation of the volume, acidity, salinity, concentration, and chemical composition of blood, lymph, and other body fluids. Under hormonal control, the kidneys continually monitor what they release into the urine to maintain a healthy chemical balance.
I am a medical student. I have one friend who is persuing his MBBS degree in Taishan Medical UNiversity. I got these notes from him.
These notes are by Dr. Bikesh, He is a famous lecturer of TMU.
These notes have helped me a lot and i also watch his lecture videos , which are great; highly simple and huge content.
I am uploading with Renal physiology. If you want some other topics i would upload for you.
"Let the Knowledge be spread" Dr. Bikesh
in this slide u are able to well known about the introduction of hormones.
categories, classification, function, structure, regulation, location, mechanism of action, how hormone regulates our body function, how it maintains the homeostasis condition.
structure of hormones.
these clearance test plays an very important role in determining the functioning capacity and working status of kidney.
and we estimate how amount of compund is excreted in the urine and absorption too.
and i also attached the mathematical caluculation to identify the metabolic valuve of urea, creatinine, inulin clearance by kidney.
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...kevinkariuki227
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
Acute scrotum is a general term referring to an emergency condition affecting the contents or the wall of the scrotum.
There are a number of conditions that present acutely, predominantly with pain and/or swelling
A careful and detailed history and examination, and in some cases, investigations allow differentiation between these diagnoses. A prompt diagnosis is essential as the patient may require urgent surgical intervention
Testicular torsion refers to twisting of the spermatic cord, causing ischaemia of the testicle.
Testicular torsion results from inadequate fixation of the testis to the tunica vaginalis producing ischemia from reduced arterial inflow and venous outflow obstruction.
The prevalence of testicular torsion in adult patients hospitalized with acute scrotal pain is approximately 25 to 50 percent
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
New Drug Discovery and Development .....NEHA GUPTA
The "New Drug Discovery and Development" process involves the identification, design, testing, and manufacturing of novel pharmaceutical compounds with the aim of introducing new and improved treatments for various medical conditions. This comprehensive endeavor encompasses various stages, including target identification, preclinical studies, clinical trials, regulatory approval, and post-market surveillance. It involves multidisciplinary collaboration among scientists, researchers, clinicians, regulatory experts, and pharmaceutical companies to bring innovative therapies to market and address unmet medical needs.
NVBDCP.pptx Nation vector borne disease control programSapna Thakur
NVBDCP was launched in 2003-2004 . Vector-Borne Disease: Disease that results from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks, and fleas. Examples of vector-borne diseases include Dengue fever, West Nile Virus, Lyme disease, and malaria.
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
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Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists
renal function test.pptx
1. ADVANCED CLINICAL BIOCHEMISTRY
RENAL FUNCTION TEST
Done by
P.S. YOGITHA
223056014
II M.Sc., Biochemistry
Dept. of Biochemistry & Biosciences
SRC, SASTRA
15-11-2022 1
4. 15-11-2022 4
Endocrine Function:
1.The kidney synthesizes hormones and also is the target organ for
other site formed hormones.
2.The kidney is the site of degradation of hormone-like insulin and
aldosterone.
3.The kidney produces hormones like :
*Erythropoietin, it stimulates RBCs production.
*Renin.
*Prostaglandins.
*Thromboxane.
*Vit. D. It converts 25-hydroxyvitamin D3 to form the biologically
active vitamin D.
8. The body has a considerable factor of safety in renal as well as hepatic tissues.
One healthy normal kidney can do the work of two, and
if all other organs are functioning properly, less than a whole kidney can be
enough.
There are certain extra renal factors which can interfere with kidney function,
specially circulatory disturbances.
Hence, methods that appraise the functional capacity of the kidneys are very
important.
Such tests have been devised and are available,
but it is stressed that no single test can measure all the kidney functions.
15-11-2022 8
9. Consequently, more than one test is indicated to assess the kidney
function.
Main functions of the kidney are:
To get rid of the body waste products of metabolism,
To get rid of foreign and non-endogenous substances,
To maintain salt and water balance, and
To maintain acid-base balance of the body.
15-11-2022 9
10. 15-11-2022 10
Glomeruli are the tiny network of blood
vessels that are the “cleaning units” of your
kidney.
They filter waste and remove extra fluids
from your blood.
When glomeruli are damaged and can't
function as they should, it's called glomerular
disease.
Many diseases and conditions can damage
the glomeruli.
Glomerular Function:
e.g., Nephrotic syndrome
11. 15-11-2022 11
The glomeruli act as filters
the fluid which passes from the blood in the glomerular capillaries into
Bowman’s capsule is of the same composition of protein-free plasma.
The effective filtration pressure which forces fluid through the filters is the
result of
(a) the blood pressure in the glomerular capillaries and
(b) the opposing osmotic pressure of
plasma proteins,
renal interstitial pressure and
intratubular pressure.
13. 15-11-2022 13
Rate of filtration is influenced by:
• Variations in BP in glomerular capillary
• Concentration of plasma proteins
• Factors altering intratubular pressure, viz.
– Rise with ureteral obstruction
– During osmotic diuresis
• State of blood vessels.
If the efferent glomerular arteriole is constricted,
the pressure in the glomerulus rises and the effective filtration pressure is
increased.
if the afferent glomerular arteriole is constricted, the filtration pressure is
reduced.
14. 15-11-2022 14
The volume of glomerular filtrate formed depends on:
• The number of glomeruli functioning at a time,
• The volume of blood passing through the glomeruli per minute and
• The effective glomerular filtration pressure.
Under normal circumstances,
about 700 ml of plasma (contained in 1300 ml of blood or approximately 25 per
cent of entire cardiac output at rest) flow through the kidneys per minute and
120 ml of fluid are filtered into Bowman’s capsule.
15. 15-11-2022 15
The volume of the filtrate is reduced in extrarenal conditions, such as
dehydration,
oligaemic shock and
cardiac failure
which diminish the volume of blood passing through the glomeruli, or lower the
glomerular filtration pressure, and
when there is constriction of
**the afferent glomerular arterioles or,
**changes in the glomeruli such as occurring in glomerulonephritis.
If the volume of glomerular filtrate is lowered below a certain point, the
kidneys are unable to eliminate waste products which accumulate in blood.
16. 15-11-2022 16
Tubular function: reabsorbtion
Whereas, the glomerular cells act only as a passive semipermeable membrane,
the tubular epithelial cells are a highly specialised tissue able to reabsorb
selectively some substances and secrete others.
About 170 litres of water are filtered through the glomeruli in 24 hours, and
only 1.5 litre is excreted in the urine.
Thus nearly 99 per cent of the glomerular filtrate is reabsorbed in the
tubules.
17. 15-11-2022 17
Glucose is present in the glomerular filtrate in the same concentration as in the
blood
but practically none is excreted normally in health in detectable amount in urine
and
the tubules reabsorb about 170 GM/day.
At an arterial plasma level of 100 mg/ 100 ml and a GFR of 120 ml/mt,
approximately 120 mg of glucose are delivered in the glomerular filtrate in each
minute.
Maximum rate at which glucose can be reabsorbed is about 350 mg/mt (Tm G)
maximum glucose tubular transport, which is an ‘active’ process.
18. 15-11-2022 18
About 50 gm of urea are filtered through the glomeruli in 24 hours,
but only 30 gram are excreted in the urine,
this is a passive diffusion.
Certain substances foreign to the body,
e.g. diodrast, para-amino hippuric acid (PAH) and phenol red are:
(1) filtered through the glomeruli and in addition are
(2) secreted by the tubules.
Thus the amount of these substances excreted per minute in the urine is
greater than that filtered through the glomeruli per minute.
Substance excreted/min in urine > filter through glomeruli/min
19. 15-11-2022 19
At low blood levels, the tubular capacity for excreting these compounds is so great
that
the plasma passing through the kidneys is almost completely cleared of them.
Another group of substances, e.g. inulin, thiosulphate, and mannitol are eliminated
exclusively by the glomeruli and
are neither reabsorbed nor secreted by the tubules.
Hence, amount of these substances excreted per minute in the urine is the same
as the amount filtered through the glomeruli per minute, thus they give the
glomerular filtration rate (GFR).
So the amount in glomeruli/min = excreted/min
20. 15-11-2022 20
Glomerular filtration rate
(GFR):
1.This is the quantity of blood cleared of substances like creatinine and urea per
unit time.
2.It is the rate in milliliter (mL) per minute that substances like creatinine and
urea filtered through the kidney glomeruli.
3. GFR depends upon:
1. Plasma concentration of the substance.
2. The excretion rate of the kidney, this will reflect:
**Renal plasma flow.
**Glomerular filtration rate.
3. This substance used should not be reabsorbed, secreted, synthesized, or
degraded in the nephron.
21. 15-11-2022 21
4.GFR is the most reliable measure of kidney function.
**GFR may be measured by giving exogenous substances like Inulin clearance.
**GFR may be measured by endogenous substances like creatinine and urea
nitrogen.
90 to 120 mL/min
22. 15-11-2022 22
Kidney function tests measure how efficiently your kidneys are working.
Most of these tests check how well your kidneys clear waste from your system.
A kidney test may involve a blood test, 24-hour urine sample or both.
27. 15-11-2022 27
What is Meant by Clearance Test?
As a means of expressing quantitatively the rate of excretion of a given substance
by the kidney, its “clearance” is frequently measured.
This is defined as a volume of blood or plasma which contains the amount of
the substance which is excreted in the urine in one minute.
It is also defined as that volume of blood or plasma cleared of the amount of the
substance found in one minute excretion of urine.
28. 15-11-2022 28
Functions of the Tubules
When the glomerular filtrate is formed, it contains almost all the crystalloids
of plasma.
In the proximal convoluted tubules, about 70% water, Na+ and Cl– as well as
100% glucose, amino acids and K+ are reabsorbed.
Urea, phosphate and calcium are partially absorbed.
The major processes occurring in renal tubules are the reabsorption or
secretion of solutes and reabsorption of water.
31. 15-11-2022 31
Renal Threshold and Tubular Maximum
Compounds whose excretion in urine is dependent on blood level are known as
threshold substances.
At normal or low plasma levels, they are completely reabsorbed and are not
excreted in urine.
But when the blood level is elevated, the tubular reabsorptive capacity is
saturated,
so that the excess will be excreted in urine.
The renal threshold of a substance is the plasma level above which the
compound is excreted in urine.
32. 15-11-2022 32
The maximum reabsorptive capacity of the substances is known as the
tubular maximum or Tm.
33. 15-11-2022 33
For glucose, the renal threshold is 180 mg/dl and Tm is 375 mg/min.
In other words, glucose starts to appear in urine when blood level is more than
180 mg/dl, and
all the glucose molecules above 375 mg are excreted in the urine.
In abnormal conditions, the renal threshold may be lowered
so that even at lower blood levels, compounds are excreted in urine,
e.g.
renal glycosuria (glucose); and
renal tubular acidosis (bicarbonate)
38. 15-11-2022 38
Reabsorption of Solutes in
Tubules
1. Sodium
In the proximal convoluted tubules, the reabsorption of sodium is by co-
transport mechanism, accompanied by glucose, amino acids.
These mechanisms are coupled with the activity of sodium-potassium-
ATPase.
There is passive transport of equivalent amounts of chloride to maintain the
electrical neutrality.
The net effect is the reabsorption of sodium chloride along with glucose,
amino acids, etc.
39. 15-11-2022 39
The co-transport of glucose is inhibited by ouabain and phlorhizin.
The sodium-Pi co-transport system is inhibited by parathyroid hormone
and facilitated by calcitriol.
In addition, Na+ to H+ exchange system also exists in the PCT.
This is an antiport system, where sodium ions are reabsorbed, in exchange
for hydrogen ions.
This also achieves a net reabsorption of bicarbonate.
When hydrogen ions are to be conserved, sodium to potassium exchange
occurs.
40. 15-11-2022 40
Most of the solute reabsorbed in
the proximal tubule is in the form
of sodium bicarbonate and sodium
chloride, and about 70% of the
sodium reabsorption occurs here.
42. 15-11-2022 42
Detailed calcium reabsorption per segment.
A: proximal tubule. Calcium is mainly reabsorbed paracellularly, partially driven by the
activity of the sodium/proton exchanger 3 (NHE3 or SLC9A3), which allows transcellular sodium
entry at the apical brush border side of cells, while the Na-K-ATPase pumps sodium out of the
cell at the basolateral side.
B: thick ascending limb. Calcium is reabsorbed by specialized and controlled paracellular
pathways involving claudin 16, 19, and 14. The driving force is provided by sodium reabsorption
through the sodium/potassium/chloride cotransporter (NKCC2 or SLC12A1) and the basolateral
Na-K-ATPase. Rising interstitial calcium concentrations activate the basolateral calcium-sensing
receptor (CaSR), which reduces NKCC2 activity and directly modulates paracellular calcium
permeability.
43. 15-11-2022 43
C: DCT-CNT. Calcium enters the cell at the apical side through TRPV5 channels,
binds intracellular calbindin D-28k, and exits the cell at the basolateral side by 2
pathways: the sodium/calcium exchanger (NCX1 or SLC8A1) and the calcium ATPase
PMCA4. Sodium enters the cell via NCC (DCT1) or epithelial sodium channel (ENaC;
DCT2 and CNT) and exits through the basolateral Na-K-ATPase.
D: collecting duct. No calcium reabsorption is taking place in this segment,
which totally depends on the calcium load delivered by the CNT. Apical CaSR-like
proteins sense urine calcium concentration. This leads to inhibition of water
reabsorption and stimulates urine acidification, decreasing the risk of stone formation.
AQP2, aquaporin-2.
44. 15-11-2022 44
2. Calcium
90% of calcium is reabsorbed from the glomerular filtrate.
However, the regulation of calcium balance is achieved at the distal
convoluted tubules.
The major factors regulating calcium reabsorption are
parathyroid hormone and
vitamin D.
3. Uric acid
It is almost completely reabsorbed in the proximal convoluted tubules,
by both active and passive carrier mediated processes.
45. 15-11-2022 45
The kidney is an
important regulator of
circulating uric acid levels, by
reabsorbing around 90% of
filtered urate, while being
responsible for 60–70% of
total body uric acid excretion.
Defective renal
handling of urate is a frequent
pathophysiologic factor
underpinning hyperuricemia and
gout.
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The drug, probenecid competes with the uric acid for reabsorption
(inhibits).
Since probenecid increases uric acid excretion, it is uricosuric.
There is also active secretion of uric acid into the tubules.
85% of the excreted uric acid is derived by tubular secretion.
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4. Urea
Urea is freely filtered by the glomerulus, but about 40% is reabsorbed
actively by the tubules.
Rate of reabsorption of urea varies inversely with tubular flow and
accounts for elevation of blood urea when renal function is low.
The concentration of urea in urine is about 70 times that of plasma.
Urea forms 80% of total urinary solutes.
Urine is roughly a 2% solution of urea.
reabsorption of nearly 40%
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5. Creatinine
Creatinine is neither reabsorbed nor secreted.
The urinary concentration is about 70% that of plasma.
6. Potassium
About 70% of potassium in the glomerular filtrate is reabsorbed by proximal
convoluted tubules.
Net secretion of K+ occurs at the distal tubules, in exchange for Na+
reabsorption, under the effect of aldosterone.
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However, when the H+ concentration is increased, H+ ions are exchanged for
sodium, instead of K+.
Urinary excretion of solutes under normal conditions.