a&e chap18 test_prep medic12

As a diffusion medium for the distribution of gases, nutrients, & waste products.

• Cellular activitites are jeopardized:
• 1)proteins denature
• 2)enzymes cease functioning
• 3)cells ultimately die.

ECF & ICF.

• 1)interstitial fluid
• 2)plasma
• 3)other body fluids

cytosol (fluid in a cell)

• 1)Amount of water you gain each day = to the amount you lose to the environment.
• 2)Involves regulating the content & distribution of water in ECF & ICF.
• 3)Reflects the creation of ion concentration gradients that are then eliminated by osmosis.

Ions released through the dissociation of inorganic compunds. (when in solution they they can conduct an electrical current)

From the food & drink consumed.

In urine, sweat, & feces excreted.

When there is neither a net gain or nor a net loss of any ion in body fluids. It primarily involves balancing the rates of absorption across the digestive tract with rates of loss at the kidneys.

When the production of hydrogen ions is equal to their loss. The pH of body fluids remains within normal limits.

Because normal metabolic operations generate a variety of acids.

Kidneys & Lungs

Steps to restore normal fluid, electrolyte, & acid-base balance.

7.35-7.45

60%

40%

• 1)interstitial fluid in the peripheral tissues
• 2)plasma of the circulating blood (capillary)
• 3)water in the ground substance of bone & dense connective tissue

• 1)lymph
• 2)cerebrospinal fluid (CSF)
• 3)synovial fluid
• 4)serous fluids
• 5)aqueous humor
• 6)fluids of the inner ear

Across cell membranes by osmosis, diffusion, & carrier-mediated processes.

Primarily across the endothelial lining of capillaries.

sodium, chloride & bicarbonate

potasium, magnesium, & phosphate ions, plus large numbers of negatively charged proteins

Water movement between the ECF & ICF. Occurs relatively rapidly, & reach equilibrium within a period of minutes to hours.

osmotic concentration of a fluid

In response to changes in the osmolarity of the ECF.

water will move from the cells into the ECF until equilibrium is restored.

water will move from the ECF into the cells, & the volume of the ICF will increase accordingly.

When the rates of gain & loss are equal for each electrolyte.

• 1) A gain or loss of electrolytes can cause a gain or loss in water.
• 2) Concentrations of individual electrolytes affect a variety of cell functions. (effects of high or low calcium & potassium ion concentrations on cardiac muscle tissue)

• Na+ (sodium)
• K+ (potassium)

• 1)they are major contributors to the osmotic concentrations of the ECF & ICF
• 2)they directly affect the normal functioning of all cells.

The dominant cation w/in the extracellular fluid. More than 90% of the osmotic concentration of the ECF results from the presence of sodium salts (principally, sodium chloride (NaCl) & sodium bicarbonate (NaHCO3)). Changes in the osmotic concentration of ECF usually reflect changes in the concentration of sodium ions.

The dominant cation in the ICF (ECF levels of this cation are normally low).

An imbalance between sodium gains & losses.

are less common but significantly more dangerous than those related to sodium balance.

At the kidneys & other sites.

the amount of sodium included in the diet.

Primarily by excretion in urine & through perspiration.

Kidneys respond to it by reabsorbing sodium ions (wh/ decreases sodium loss). Increases in it also strongly affect the loss of potassium ions.

kidneys respond to it by increasing the loss of sodium ions

98%

• 1)rate of gain across the digestive epithelium
• 2)rate of loss in urine (strongly affected by aldosterone)
• 3)rate of gain proportional to the amount in the diet

• 1)ion pumps sensitive to aldosterone reabsorb sodium ions from the filtrate in exchange for potassium ions from the interstitial fluid
• 2)high plasma concentrations of potassium ions also stimulate aldosterone secretion directly
• 3)when potassium levels rise in the ECF, aldosterone levels climb, & additional potassium ions are lost in the urine.

It would cause a reduction of fluid in the ICF; the ingested salt would temporarily increase the osmolarity of the ECF, so water would shift from the ICF to the ECF.

Fluid loss through perspiration, urine formation, & respiration would increase the osmolarity of blood & other body fluids.

• 1) disrupt stability of cell membranes
• 2) alter protein structure
• 3) change activities of important enzymes
• (you could not survive long below 6.8 or above 7.7)

pH of blood falls below 7.35

pH of blood exceeds 7.48

• 1) CNS function deteriorates - comatose
• 2) cardiac contractions grow weak & irregular - signs of heart failure develop
• 3) peripheral vasodilation produces dramatic drop in BP - circulatory collapse can occur

CO2 + H2O <-> H2CO3 <-> H+ + HCO3-

• carbon dioxide: CO2
• water: H2O
• carbonic acid: H2CO3
• hydrogen ion: H+
• bicarbonate ion: HCO3-

• at the lungs -> H2CO3 breaks down into CO2 & H2O (the CO2 diffuses into the aveoli)
• in the peripheral tissues -> CO2 in solution interacts w/ H2O to form H2CO3
• [occurs very rapidly in presence of carbonic anhydrase]

• 1) red blood cells
• 2) liver & kidney cells
• 3) parietal cells of the stomach

inverse

• CO2 rise...
• additional H+ & HCO3- released...
• pH goes down (more acidic because more H+)

PCO2

At the alveoli, CO2 diffuses into the atmosphere and the number of H+ & HCO3- drops.

dissolved compunds that can provide or remove hydrogen ions (H+) (thereby stabilizing the pH of a solution)

• 1) weak acids that can donate H+
• 2) weak bases that can absorb H+

consists of a combination of a weak acid & its dissociation products: a hydrogen ion & an anion.

• 1) protein buffer system
• 2) carbonic acid-bicarbonate buffer system
• 3) phosphate buffer system

stimulate the respiratory center in the medulla ablongata, resulting in an increased breathing rate. as a result, more CO2 is eliminated, & pH rises.

fatty acids are catabolized, producing ketone bodies, wh/ are acids that lower the body's pH. The eventual result is called ketacidosis.

• 1) large amounts of stomach acid (HCI) are lost from the body
• 2) to replace the lost H+, hydrogen ions & bicarb ions are fromed from CO2 & H2O withing the parietal cells
• 3) the release of bicar ions into the blood (in exchange for chloride ions) raises the body's pH, wh/ would cause metabolic alkalosis