Terms in this set (39)
- Glomerular Capillary Blood Pressure: Favors filtration (55mmHg)
- Plasma-Colloid Osmostic Pressure: Opposes filtration (30mmHg)
- Bowman's Capsure Hydrostatic Pressure: Opposes filtration (15mmHg)
- Net Filtration Pressure (Difference between force favoring filtration and forces opposing filtration): Favors filtration [55 - (30 + 15)] = 10mmHg
What is glomerular filtration?
Glomerular Filtration. Filtration of blood through the glomerular barrier, known as "Glomerular Filtration", is the first step in the process of urine formation. Blood entering the glomerular capillaries is filtered into Bowman's Capsule from where it enters the remainder of the nephron. The glomerular barrier is highly permeable and nearly 20%...
Why is the glomerular barrier so permeable?
The physical basis of this incredible permeability is the fenestrated nature of the glomerular endothelium which facilitates molecular transport across the glomerular capillaries. The glomerular barrier allows for large volumes of fluid filtration into bowman's space but also exerts some selectivity on the molecules that are allowed to cross.
What is a glomerular filtration rate (GFR) test?
Your kidneys work to filter waste products and excess fluids from your blood, which are then released from your body as urine. A glomerular filtration rate (GFR) test measures how well your kidneys are carrying out their filtration function. This test usually involves testing your blood for a waste product called creatinine.
What is the function of the glomerular basement membrane?
The glomerular basement membrane is a tight meshwork of negatively charged glycoproteins. This meshwork not only provides a physical barrier to large molecules, its negative charge repels other negatively-charged molecules.
What is glomerular filtration opposed by?
The forces that govern filtration in the glomerular capillaries are the same as any capillary bed. Capillary hydrostatic pressure (Pc) and Bowman's space oncotic pressure (πi) favor filtration into the tubule, and Bowman's space hydrostatic pressure (Pi) and capillary-oncotic pressure (πc) oppose filtration.
What are the opposing forces of the filtration pressure at the glomerulus?
Solution : Glomerular hydrostatic pressure (55 mm Hg) is the force that promotes filtration. The colloidal osmotic pressure (30 mm Hg) and the capsular hydrostatic pressure (15 mm Hg) are the two opposing forces.
Which factors would reduce glomerular filtration?
In this population-based study, we examined factors associated with glomerular filtration rates (GFR) in both genders. The findings of our study showed that obesity, diabetes, blood urea nitrogen, atherogenic factor, hypertension, meat consumption, and smoking were associated with lower GFR.
What Cannot pass glomerular filtration?
Under normal conditions, high molecular weight proteins in the plasma (e.g., albumin and globulin) cannot pass through the filtration membrane due to the effects of the size barrier and charge barrier of the glomerular capillary filtration membrane.
Which of the following forces oppose glomerular filtration quizlet?
Which of the following forces oppose glomerular filtration? capsular hydrostatic pressure (HPc) and blood colloid osmotic pressure (OPg).
What two pressures oppose filtration and what are their values?
Urinary SystemQuestionAnswerWhat two pressures oppose filtration and what are their values?a. Colloid Osmotic Pressure b. Capsular Space PressureWhat is the normal net filtration pressure?17 mmHgWith a glomerular filtration rate of 125 ml/min, how much plasma would be filtered per day? (in 24 hours)180 L51 more rows
What factors affect glomerular filtration rate quizlet?
The factors which determine GFR are the net effective filtration pressure, permeability characteristics of the glomerular membrane and its surface area.
Does dehydration decrease GFR?
Conclusions: In fasting adults, high hydration lowered GFR and increased natriuresis. After a meat meal, GFR increased only in the high hydration regimen and natriuresis only in the low hydration regimen. Hydration affects GFR and natriuresis under fasting conditions and after a meat meal.
Which of the following are mechanisms that control GFR?
So, the correct answer is 'JGA, DCT, Afferent arteriole, Renin'.
Which types of substances are usually not cleared by glomerular filtration and why?
Large molecules or protein-bound drugs do not get filtered at the glomerulus because of size and electrical hindrance. The kidneys receive approximately 25% of cardiac output, so the major driving force for glomerular filtration is the hydrostatic pressure within the glomerular capillaries.
What molecules Cannot get filtered from the blood and become part of glomerular filtrate?
Filterable blood components include water, nitrogenous waste, and nutrients that will be transferred into the glomerulus to form the glomerular filtrate. Non-filterable blood components include blood cells, albumins, and platelets, that will leave the glomerulus through the efferent arteriole.
Which of the following substances does not pass through the filtration membrane?
Answer and Explanation: The substances that cannot pass through the filtration membrane of the kidneys are D. Proteins.
Which are the 3 pressures involved in glomerular filtration?
The three pressures operating at the filtration membrane are glomerular hydrostatic pressure, colloid osmotic pressure, and capsular hydrostatic pressure.
What forces filtration at the glomerular capsule?
hydrostatic pressure: The pushing force exerted by the pressure in a blood vessel. It is the primary force that drives glomerular filtration.
Which of the following forces Favour glomerular filtration?
Solution : 1. Glomerular pressure is the chief force that promotes Glomerular filtration.
2 The two opposing forces are the plasma proteins in the capillaries contributed by the colloidal osmotic pressure and the capsular hydrostatic pressure due to the fluids in the glomerular capsule.
What are the forces responsible for net filtration pressure?
The net filtration pressure (NFP) represents the interaction of the hydrostatic and osmotic pressures, driving fluid out of the capillary. It is equal to the difference between the CHP and the BCOP.
What happens to the plasma oncotic pressure in the glomerular capillaries as a result of ultrafiltration?
As a result of ultrafiltration, the plasma oncotic pressure in the glomerular capillaries increases until the filtration gradient is abolished and filtration ceases before the efferent arteriole is reached.
How can GFR be varied?
Experiments performed with arterial blood pressure held constant show that GFR can be varied by experimentally altering fluid flow through the macula densa segment of the distal nephron: elevating flow through the macula densa leads to a decrease in GFR, while reducing flow to the macula densa leads to an increase in GFR.
What does constriction of the efferent arteriole lead to?
2. Constriction of the efferent arteriole leads to increased Pglom and increased GFR. Dilation of the efferent arteriole does the opposite.
What is the first step in the formation of urine?
the first step in formation of urine is ultra filtration of plasma across the glomerular capillaries into Bowman's capsule.
Which muscle cells regulate the degree of constriction of the afferent and efferent arterioles?
Sympathetic input to smooth muscle cells surrounding the afferent and efferent arterioles can regulate the degree of constriction of these two arterioles.
Which organ has the greatest resistance to blood flow?
The afferent arteriole provides the single greatest resistance to blood flow in the kidney and thus, has the greatest drop in blood pressure from 100 to 55 mmHg. Pressure drop across the. efferent arteriole, which is in series with the afferent arteriole, though, is also high from 55 to 25 mmHg.
Which arterioles have the ability to sense and respond to tension in the vessel wall?
The afferent arterioles have the ability to sense and respond to tension in the vessel wall.
How should I prepare for a GFR test?
Your doctor will give you instructions on how to prepare for your GFR test. If you aren‘t sure, it ‘s best to ask your doctor.
How to check kidney function if you have diabetes?
If you have diabetes, your doctor will check your kidney function yearly by testing and measuring your GFR and urine albumin levels. To lower your risk of kidney disease, it’s important to stick to your treatment plan and to manage your blood pressure.
What is a globular filtration rate?
Glomerular filtration rate is a test that’s important in the diagnosis and monitoring of kidney disease. Keep reading to learn more about this test, what the results mean, and how it plays a role in diabetic kidney disease.
What does a GFR of 60 mean?
A GFR of 60 or higher is considered within the normal range. A GFR lower than 60 may be an indication that you have kidney disease.
Why is a GFR test important?
Because early kidney disease often has no symptoms, a GFR test is a valuable tool for monitoring kidney function. This is particularly important if you’re at an increased risk of kidney disease, especially if you have diabetes.
Why is diabetes a risk factor for kidney disease?
People with diabetes are at an increased risk of developing kidney disease. This is because high blood sugar levels can damage the blood vessels in your kidneys. This can affect how well your kidneys are able to filter your blood.
What is the function of the kidneys?
Your kidneys filter wastes and extra fluids from your body using tiny blood vessels called capillaries. High levels of sugar in your blood — which happens with diabetes — can damage blood vessels in your body, including the tiny blood vessels in your kidneys.
Why does the patient secrete more ADH?
A) The patient will secrete more ADH so that more water can be reabsorbed from the filtrate.
How many nephrons are there in each kidney?
E) There are about a billion nephrons in each kidney.
How much of the water filtered from the glomerulus is returned to the blood?
A) returns 99% of the water filtered from the glomerulus to the blood.
What is reflex D?
D) is a reflex that cannot be voluntarily controlled.
What is the term for urination?
12. Micturition, which is also called urination or voiding,
Where are the nephrons located?
B) Most of the nephrons are located entirely in the renal medulla.
What is the physical basis of glomerular filtration?
The physical basis for the size and charge selectivity of glomerular filtration is that of the glomerular basement membrane and its supporting podocytes, although the basement membrane appears to be most important. The glomerular basement membrane is a tight meshwork of negatively charged glycoproteins.
What is the permeability of glomerular capillaries?
As mentioned, the glomerular capillaries display an enormous permeability to water and small molecules far beyond that of most other capillary beds. The physical basis of this incredible permeability is the fenestrated nature of the glomerular endothelium which facilitates molecular transport across the glomerular capillaries.
What is the first step in the process of urine formation?
Glomerular Filtration. Filtration of blood through the glomerular barrier, known as "Glomerular Filtration", is the first step in the process of urine formation. Blood entering the glomerular capillaries is filtered into Bowman's Capsule from where it enters the remainder of the nephron.
How many layers are there in the glomerular barrier?
The Glomerular Barrier. The glomerular barrier is composed of three basic layers which separate blood from Bowman's Space (See Glomerular Histology for a more in-depth discussion). The first layer is that ...
Which layer of the glomerular capillary membrane is fenestrated?
The first layer is that of glomerular capillary endothelial cells which are fenestrated, allowing for high fluid permeability. The second layer is that of the glomerular basement membrane which invests the fenestrated endothelial cells.
How does the molecular weight of a molecule affect its capacity for filtration?
As the molecular weight of a molecule increases, its capacity for filtration progressively and rapidly declines. Furthermore, for any given sized molecules, its capacity for filtration progressively and rapidly declines as its charge becomes more negative.
Is the glomerular barrier permeable?
The glomerular barrier is highly permeable and nearly 20% of the plasma volume entering the glomerular capillaries is filtered through into the nephron. However, filtration is also highly selective and only allows water and small molecules pass through the glomerular barrier.
