Renal week 1 Flashcards
What are the two major sources for how water is added to the body?
(1) it is ingested in the form of liquids or water in food, which together normally add about 2100 ml/day to the body fluids, and (2) it is synthesized in the body by oxidation of carbohydrates, adding about 200 ml/day. These mechanisms provide a total water intake of about 2300 ml/day.
The total body fluid is distributed mainly between two compartments: the_______ fluidand the_______ fluid.
The extracellular fluid is divided into theinterstitial fluidand the bloodplasma
The total body fluid is distributed mainly between two compartments: theextracellular fluidand theintracellular fluid.
The extracellular fluid is divided into theinterstitial fluidand the bloodplasma
What is transcellular fluid?
This compartment includes fluid in the synovial, peritoneal, pericardial, and intraocular spaces, as well as the cerebrospinal fluid; it is usually considered to be a specialized type of extracellular fluid, although in some cases its composition may differ markedly from that of the plasma or interstitial fluid. All the transcellular fluids together constitute about 1 to 2 liters.
True/False: a person grows older, the percentage of total body weight that is fluid gradually decreases
True. The percentage of total body weight that is fluid gradually decreases
This decrease is due in part to the fact that aging is usually associated with an increased percentage of the body weight being fat, which decreases the percentage of water in the body.
Are extracellular (plasma and interstitial) fluids similar?
Yes. Highly permeable capillary membrane
Protein level > in plasma because of low membrane permeability
What are the major extracellular cations?
Na and Cl, little bit of Hco3
What are the major intracellular cations?
Potassium, mag
What is intracellular fluid permeable to?
Highly permeable to water not electrolytes (semi-permeable)
Separated by cell membrane
he composition of extracellular fluid is carefully regulated by various mechanisms, but especially by the _________
he composition of extracellular fluid is carefully regulated by various mechanisms, but especially by the KIDNEYS
What is the gibbs donnon equilibrium?
When two solutions containing ions are separated by membrane that is permeable to some of the ions and not to others an electrochemical equilibrium is established.
Because of theDonnan effect,the concentration of positively charged ions (cations) is slightly greater (~2 percent) in the plasma than in the interstitial fluid.
What are the amounts of extracellular fluid distributed between the plasma and interstitial spaces are determined by?
balance of hydrostatic and colloid osmotic forces across the capillary membranes.
What is the distribution of fluid between intracellular and extracellular compartments determined by?
osmotic effect of the smaller solutes—especially sodium, chloride, and other electrolytes—acting across the cell membrane
The rate of diffusion of water is called?
therate of osmosis.
Just read this
Because cell membranes are relatively impermeable to most solutes but are highly permeable to water (i.e., they are selectively permeable), whenever there is a higher concentration of solute on one side of the cell membrane, water diffuses across the membrane toward the region of higher solute concentration. Thus, if a solute such as sodium chloride is added to the extracellular fluid, water rapidly diffuses from the cells through the cell membranes into the extracellular fluid until the water concentration on both sides of the membrane becomes equal. Conversely, if a solute such as sodium chloride is removed from the extracellular fluid, water diffuses from the extracellular fluid through the cell membranes and into the cells.
One osmole (osm) = 1 mole (mol) (6.02 x 1023)*
1 mole (mol) (6.02 x 10 to the 23rd)*
Osmolality=
Osmoles / kg of water
Osmolarity
Osmoles / liter of solution
Osmosis is the net diffusion of water across a ________ _______
Osmosis is the net diffusion of water across a selective membrane
- high water concentration to low water concentration
Osmotic Pressure refers to the amount of pressure required to prevent _______
Osmosis.
Pressure applied in opposite direction of osmosis
Interstitial Fluid & Plasma
80% due to sodium & chloride
Plasma is 1 mOsm/L > interstitial fluid
Plasma proteins maintain 20 mmHg greater pressure in capillaries than surrounding tissues
Intracellular Fluid
Almost 50% due to potassium ions
Remainder divided among other intracellular substances
Total osmolarity of each compartment @ 300 mOsm/L
What is the most important difference between plasma and interstitial fluids?
The higher concentration of protein in the plasma.
Because the capillaries have a low permeability to the plasma proteins, only small amounts of proteins are leaked into the interstitial spaces in most tissues.
Hyper/hypo/isotonic
Hyper - water out, cell shrinks
Iso - equal
Hypo - water in, cell expands
If ahypertonicsolution is added to the extracellular fluid..
The net effect is an increase in extracellular volume (greater than the volume of fluid added), a decrease in intracellular volume, and a rise in osmolarity in both compartments.
If ahypotonicsolution is added to the extracellular fluid
the osmolarity of the extracellular fluid decreases and some of the extracellular water diffuses into the cells until the intracellular and extracellular compartments have the same osmolarity (C). Both the intracellular and the extracellular volumes are increased by the addition of hypotonic fluid, although the intracellular volume increases to a greater extent.
HYPONATREMIA
Excess water
Loss of sodium
Diarrhea & Vomiting
Diuretic abuse
Addison’s Disease
Excess water retention (ADH)
HYPERNATREMIA
Loss of water
Excess of sodium
Lack of ADH
Diabetes insipidus
Dehydration
Aldosterone secretion
A primary loss of sodium chloride usually results inhyponatremia and dehydrationand is associated with decreased ________ fluid volume.
extracellular
If plasma sodium concentration rapidly falls below _____ to ______ mmol/L, brain swelling may lead to seizures, coma, permanent brain damage, and death. Because the skull is rigid, the brain cannot increase its volume by more than about ____ percent without it being forced down the neck(herniation),which can lead to permanent brain injury and death.
115 to 120
10%
A rapid _______ in plasma sodium concentration, for example, can cause brain cell edema and neurological symptoms, including headache, nausea, lethargy, and disorientation.
reduction
Primary loss of _____ from the extracellular fluid results in_______ and dehydration.
water, hypernatremia
Causes of hypernatremia
An inability to secrete ______ ______, which is needed for the kidneys to conserve water. As a result of lack of antidiuretic hormone, the kidneys excrete large amounts of dilute urine (a disorder referred to as“central” diabetes insipidus), causing dehydration and increased concentration of sodium chloride in the extracellular fluid.
In certain types of renal diseases, the kidneys cannot respond to antidiuretic hormone, causing a type of“______” diabetes insipidus.
antidiuretic hormone
nephrogenic
Thus, in analyzing abnormalities of plasma sodium concentration and deciding on proper therapy, one should first determine whether the abnormality is caused by a primary loss or gain of sodium or a primary loss or gain of water.
Just read
What is more common, hypernatremia or hyponatremia?
Hyponatremia is much more common
When do severe symptoms of hypernatremia start to show?
severe symptoms usually occur only with rapid and large increases in the plasma sodium concentration above 158 to 160 mmol/L. One reason for this phenomenon is that hypernatremia promotes intense thirst and stimulates secretion of antidiuretic hormone, which both protect against a large increase in plasma and extracellular fluid sodium.
How do you correct hypernatremia?
Correction of hypernatremia can be achieved by administering hypo-osmotic sodium chloride or dextrose solutions. However, it is prudent to correct the hypernatremia slowly in patients who have had chronic increases in plasma sodium concentration because hypernatremia also activates defense mechanisms that protect the cell from changes in volume.
What compartment does edema usually occur?
Occurs mostly in the extracellular fluid compartment
What are the two general causes of extracellular edema?
Abnormal leakage from plasma
-Excessive capillary filtration rate
Filtration dependant on permeability & surface area of capillary
Starling factors: hydrostatic pressure & colloid osmotic pressure
Lymphatic failure to return fluids to blood
-Lymphatic blockage preventing return of proteins to plasma
Increased interstitial colloid osmotic pressure
Cancer, surgery, infection (filaria nematodes)
filaria nematodes (Wuchereria bancrofti)
Blockage of lymph flow can be especially severe with infections of the lymph nodes, such as occurs with infection byfilaria nematodes (Wuchereria bancrofti),which are microscopic, threadlike worms. The adult worms live in the human lymph system and are spread from person to person by mosquitoes. People with filarial infections can have severe lymphedema andelephantiasisand men can have swelling of the scrotum, calledhydrocele. Lymphatic filariasis affects more than 120 million people in 80 countries throughout the tropics and subtropics of Asia, Africa, the Western Pacific, and parts of the Caribbean and South America.
Causes of abnormal leakage from plasma
Increased capillary filtration coefficient
Increased capillary hydrostatic pressure
Decreased plasma colloid osmotic pressure
What are the causes of extracellular edema?
Increased capillary pressure
- Retention of sodium & water
- High venous pressure
- Decreased arteriole resistance
Decreased plasma proteins
Increased capillary permeability
- Immune reactions
- Infection & toxins
- Burns & ischemia
Blockage of lymph return
Edema Caused by Heart Failure
The heart fails to pump blood normally from the veins into the arteries, which raises venous pressure and capillary pressure, causing increased capillary filtration.
The arterial pressure tends to fall, causing decreased excretion of salt and water by the kidneys, which causes still more edema.
Blood flow to the kidneys is reduced and this reduced blood flow stimulates secretion of renin, causing increased formation of angiotensin II and increased secretion of aldosterone, both of which cause additional salt and water retention by the kidneys.
Safety Factors That Prevent Edema
Low interstitial compliance (usually -3 mmHg)
Ability to increase lymphatic drainage
“Wash down” of interstitial fluid proteins (as lymphatic flow increases proteins are washed away)
Total safety factor against edema is about ____
17 mmHg (3,7,7)
Capillary pressure can _____ before significant edema occurs
double
What is the functional unit of the kidney?
The Nephron
Where does plasma filtration occur?
The glomerulus
Renal bloodflow is ___% of cardiac output
22%
Highest metabolism is in the ____ ____
renal cortex
True/false: renal blood flow is the highest of any organ
True
True/false: Each kidney has 1.25 million nephrons
True
What are the 2 types of nephrons?
Cortical
-Short loops of Henle, extend to outer medulla
-Outnumber juxtamedullary nephrons ~7:1
Juxtamedullary
- Extend deep into medulla with long loops of
Henle
- Play a big role in concentrating urine
After age 40 years, the number of functioning nephrons usually decreases about 10 percent every 10 years; thus, at age 80 years, many people have _____ fewer functioning nephrons than they did at age 40 years.
40% fewer at 80
