Chapter 26

water content

varies in different body organs and tissues from as little as 8 percent in the teeth to as much as 85 percent in the brain.

majority of body fluid concentrated

in ICF

intracellular fluid

fluid within cells and is principal component of cytosol/cytoplasm. makes up about 60 percent of total water in human body. Fluid volume tends to be very stable because amount of water in living cells is closely regulated

Extracellular fluid

accounts for the other one-third of body's water content. Approximately 20 percent of is found in plasma. Other water-based ECF include cerebrospinal fluid, synovial fluid, pleural fluid, pericardial fluid, peritoneal fluid, aqueous humor

plasma

travels through the body in blood vessels and transports a range of materials including blood cells, proteins including clotting factors and antibodies, electrolytes, nutrients, gases, and wastes

interstitial fluid

Gases, nutrients, and waste materials travel between capillaries and cells through this

ADH produced

the hypothalamus and released by the posterior pituitary gland. It causes the kidneys to retain water, constricts arterioles in the peripheral circulation, and affects some social behaviors in mammals.

calcium and phosphate regulated

through actions of three hormones: parathyroid hormone (PTH), dihydroxyvitamin D (calcitriol), and calcitonin. All three are released or synthesized in response to the blood levels of calcium.

PTH

released from the parathyroid gland in response to a decrease in the concentration of blood calcium. The hormone activates osteoclasts to break down bone matrix and release inorganic calcium-phosphate salts. increases the gastrointestinal absorption of dietary calcium by converting vitamin D into dihydroxyvitamin D (calcitriol), raises blood calcium levels by inhibiting the loss of calcium through the kidneys. also increases the loss of phosphate through the kidneys.

calcitriol

an active form of vitamin D that intestinal epithelial cells require to absorb calcium.

calcitonin

released from the thyroid gland in response to elevated blood levels of calcium. The hormone increases the activity of osteoblasts, which remove calcium from the blood and incorporate calcium into the bony matrix

respiratory tract

can adjust the blood pH upward in minutes by exhaling CO2 from the body

renal system

adjust blood pH through the excretion of

hydrogen ions (H+) and the conservation of bicarbonate, but this process takes hours to days to have an effect.

blood plasma buffer system

functioning in blood plasma include plasma proteins, phosphate, and bicarbonate and carbonic acid buffers. The kidneys help control acid-base balance by excreting hydrogen ions and generating bicarbonate that helps maintain blood plasma pH within a normal range.

protein buffer system

work predominantly inside cells. Nearly all proteins can function as buffers. Proteins are made up of amino acids which contain positively charged amino groups and negatively charged carboxyl groups. The charged regions of these molecules can bind hydrogen and hydroxyl ions and thus function as buffers. Buffering by proteins accounts for two-thirds of the buffering power of the blood and most of the buffering within cells.

hemoglobin

the principal protein inside of red blood cells and accounts for one-third of the mass of the cell. During the conversion of CO2 into bicarbonate, hydrogen ions liberated in the reaction are buffered by hemoglobin which is reduced by the dissociation of oxygen. This buffering helps maintain normal pH. The process is reversed in the pulmonary capillaries to re-form CO2 which then can diffuse into the air sacs to be exhaled into the atmosphere

phosphate buffer system

found in blood in two forms: sodium dihydrogen phosphate which is a weak acid and sodium monohydrogen phosphate which is a weak base. When Na2 HPO24- comes into contact with a strong acid, such as HCl, the base picks up a second hydrogen ion to form the weak acid Na2 H2 PO4 − and sodium chloride, NaCl. When Na2 HPO24 − (the weak acid) comes into contact with a strong base, such as sodium hydroxide (NaOH), the weak acid reverts back to the weak base and produces water. Acids and bases are still present, but they hold onto the ions.

metabolic acidosis

occurs when the blood is too acidic (pH below 7.35) due to too little bicarbonate, a condition called primary bicarbonate deficiency. At the normal pH of 7.40, the ratio of bicarbonate to carbonic acid buffer is 20:1. If a person's blood pH drops below 7.35, then he or she is in this state.

cause of metabolic acidosis

presence of organic acids or excessive ketones in the blood.

metabolic alkalosis

opposite of metabolic acidosis. It occurs when the blood is too alkaline (pH above 7.45) due to too much bicarbonate (called primary bicarbonate excess).

A transient excess of bicarbonate in the blood can follow ingestion of excessive amounts of bicarbonate, citrate, or antacids for conditions such as stomach acid reflux—known as heartburn. The oversecretion of ACTH results in elevated aldosterone levels and an increased loss of potassium by urinary excretion.

cushing's disease

which is the chronic hypersecretion of adrenocorticotrophic hormone (ACTH) by the anterior pituitary gland, can cause chronic metabolic alkalosis.

metabolic alkalosis causes

loss of hydrochloric acid from the stomach through vomiting, potassium depletion due to the use of diuretics for hypertension, and the excessive use of laxatives, cushing's disease, heartburn

respiratory acidosis

occurs when the blood is overly acidic due to an excess of carbonic acid, resulting from too much CO2 in the blood. can result from anything that interferes with respiration, such as pneumonia, emphysema, or congestive heart failure.

respiratory alkalosis

occurs when the blood is overly alkaline due to a deficiency in carbonic acid and CO2 levels in the blood. This condition usually occurs when too much CO2 is exhaled from the lungs, as occurs in hyperventilation, can be due to fear, fever, infections, hypoxia, or abnormally high levels of catecholamines, such as epinephrine and norepinephrine, aspirin overdose—salicylate toxicity—can result in this state as the body tries to compensate for initial acidosis