Buffers and Fluid Compartments in Physiology

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Questions and Answers

What is the primary function of buffers in the body?

To maintain a constant temperature.

To increase the rate of respiration.

To release H+ ions in solution.

To convert strong acids or bases into weak ones. (correct)

Which buffer system is considered the first line of defense against pH changes in the body?

Renal buffer system

Phosphate buffer system

Respiratory buffer system

Bicarbonate buffer system (correct)

Which of the following conditions results from an excess of carbonic acid in the body?

Alkalosis

Hydration

Acidosis (correct)

Homeostasis

What role do physiological buffers play in pH regulation?

They stabilize pH by altering respiratory and urinary output. Signup and view all the answers

What is the normal pH range that the body maintains?

7.35 to 7.45 Signup and view all the answers

What percentage of the body’s water is found in intercellular fluid?

65% Signup and view all the answers

Which mechanism primarily stimulates thirst when the total body water declines?

Physical changes detected by the hypothalamus Signup and view all the answers

What is the primary outcome when the concentration of electrolytes in tissue fluid rises?

Water moves out of the cells. Signup and view all the answers

Which type of disorder involves an imbalance resulting in excessive water retention in the body?

Fluid excess Signup and view all the answers

What role does ADH (antidiuretic hormone) play when body water is low?

It prompts kidneys to reabsorb more water. Signup and view all the answers

What is the primary regulatory hormone that adjusts sodium excretion?

Aldosterone Signup and view all the answers

Which electrolyte imbalance is considered a medical emergency due to its potential to cause cardiac arrhythmias?

Potassium Signup and view all the answers

What is the normal plasma level range for phosphate in mg/dL?

2.5 to 4.5 Signup and view all the answers

Which of the following is NOT a function of calcium in the body?

Muscle relaxation Signup and view all the answers

What primarily determines the pH of a solution?

Concentration of hydrogen ions Signup and view all the answers

What condition results from losing more water than sodium and can lead to hypovolemic shock?

Dehydration Signup and view all the answers

Which of the following best describes the condition of fluid excess occurring with renal failure?

Fluid excess with isotonic extracellular fluid Signup and view all the answers

Which electrolyte has a normal plasma range of 3.5 to 5.3 mEq/L?

Potassium Signup and view all the answers

Fluid accumulation in interstitial spaces is referred to as what condition?

Edema Signup and view all the answers

What is the main characteristic of dehydration compared to volume depletion?

Fluid loss is greater than sodium loss Signup and view all the answers

Study Notes

Buffers

Buffers resist changes in pH by converting strong acids or bases into weak ones
Two categories: chemical buffers and physiological buffers
Chemical buffers include: bicarbonate buffer system, phosphate buffer system, and protein buffer system
Physiological buffers use the respiratory and urinary systems to alter the output of acids, bases, or CO2.
Not all buffer systems begin working at the same time. The order is: chemical buffers, respiratory system, then renal system.
Maintaining the body's pH range of 7.35 to 7.45 depends on a precise ratio of bicarbonate ions to carbonic acid
An excess of carbonic acid causes acidosis
An excess of bicarbonate causes alkalosis

Fluid Compartments

Intercellular fluid (ICF) - Most of the body's water (about 65%) resides inside the cells
Extracellular fluid (ECF) - 35% of body's water is outside the cells
Interstitial Fluid - Extracellular fluid includes the fluid between the cells inside tissue
ICF and ECF continually mingle
If the concentration of electrolytes of tissue fluid rises, water moves out of the cells and into the tissue
If the osmolarity of tissue fluid falls, water moves out of the tissue and into the cells

Balancing Water Gain and Loss

Normally the amount of water gained and lost by the body through the course of the day is equal
An adult gains and loses about 2500 mL of fluid each day
Most fluid intake occurs through eating and drinking
Cells produce water as a byproduct of metabolic reactions (Metabolic water)
Fluid is lost through the kidneys as urine, the intestines as feces, the skin by sweat and diffusion, and the lungs through expired air

Regulation of Intake and Output

The body uses mechanisms that adjust fluid intake as well as urine output
When total body water declines, physical changes stimulate the thirst center in the hypothalamus, salivation decreases causing dry mouth and thirst, and water consumption occurs
To decrease urine output: physical changes stimulate the hypothalamus, ADH prompts the collecting ducts of the kidneys to reabsorb more water and produce less urine
The rate of fluid loss slows until water is ingested

Disorders of Water Balance

Three types of disorders: fluid deficiency, fluid excess, and fluid accumulation
Fluid deficiency results when output exceeds intake
Two types of fluid deficiency: volume depletion (blood loss or loss of fluids like diarrhea) and dehydration (losing more water than sodium)
Dehydration can lead to hypovolemic shock
Fluid excess occurs when fluid intake exceeds output.
The kidneys usually compensate for excess fluid, but renal failure is one cause of fluid excess
Fluid excess can manifest in: water intoxication (consuming excessive amounts of water or replacing water losses with only water) and fluid excess (ECF remains isotonic) - retention of both sodium and water
Fluid accumulation leads to edema (fluid accumulates in interstitial spaces)
Fluid can accumulate in organs and tissues of the body (commonly lungs and brain)

Electrolyte Balance

Electrolytes are substances that dissociate into ions in water
Electrolyte levels are measured in plasma
Electrolyte Levels (plasma):

Electrolyte	Range (mEq/L)
Sodium	135 to 145
Potassium	3.5 to 5.3
Calcium	8.2 to 10.2

Chloride

Most abundant extracellular anion

Phosphate

Plasma level: 2.5 to 4.5 mg/dL

Sodium

Main electrolyte in extracellular fluid, also the chief cation.
Sodium levels are primarily regulated by aldosterone and ADH.
Aldosterone adjusts sodium excretion
ADH adjusts water excretion

Potassium

Chief cation of intracellular fluid
Works hand-in-hand with sodium
Potassium imbalances are the most dangerous of any electrolyte imbalance, very high levels considered a medical emergency
Imbalances can cause life-threatening cardiac arrhythmias

Calcium

Functions: strengthening bones, muscle contraction, nerve transmission, blood clotting
Plasma calcium levels are regulated by parathyroid hormone

Chloride and Phosphate

Chloride is the most abundant extracellular anion.

Acid-Base Balance

One of the most important factors influencing homeostasis is the body's balance between acids and bases.

Acids and Bases

The pH of a solution is determined by its concentration of hydrogen (H+) ions.

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Description

This quiz covers the concepts of buffers, their types, and the importance of fluid compartments in the human body. Learn how chemical and physiological buffers maintain pH levels, and explore the distinction between intercellular and extracellular fluids. Perfect for students studying physiology and biochemistry.