Chapter 3: Water and electrolytes

03/09/2025- finished Flashcard set ~X

Since the structure of water is unique, what ability does it have?

ability to sustain life

How much water makes up the earths surface and the human body?

• 70% water

• 60-70% water (newborns 70%, adult males 60%, and adult females 55%)

The water present in the body is a mixture of what?

• cells

• proteins

• glucose

• lipoproteins

• electrolytes

• other substances

• water

Electrolytes

Substances that when dissolved in water, dissociate into charged ions

Cations

positively charged electrolytes

Anions

negatively charged electrolytes

In the human body, water and solutes are distributed into two compartments:

• Intracellular- in the cell (2/3 of body fluids)

• Extracellular- outside the cell (1/3 of body fluids)

Extracellular water compartments are subdivided into the spaced between cells also known as:

• Interstitial fluid- in between cells (ex. cerebrospinal fluid, synovial fluids)

• Intravascular- blood plasma

What are the functions of water?

1. Solvent- many chems dissolve in water

2. Vehicle- carries nutrients and wastes

3. Medium for chemical reactions- participates in chemical reactions

4. Lubricant/ shock absorber- Joints, saliva, mucus

5. Temperature regulator- through evaporation of sweat from skin. (Hypothalamus regulates it)

   1. It takes a lot of energy to change the temp of water.

   2. evaporative cooling.

6. Maintains blood volume

Osmoregulation

the control of fluid balance and composition in the body. One of the essential homeostatic functions of the body is to maintain fluid balance and the differences in solute composition between cells and their surrounding environment.

Hypertonic

There is more solutes outside the cell than inside. Therefore, water leaves the cell. (cremation)

Isotonic

solute concentration inside and outside the cell is the same. there is equilibrium.

Hypotonic

There is more solutes inside the cell than outside. Therefore, water will move into the cell. (Hemolysis)

where is the thermoregulatory center of the brain?

Hypothalamus

Human daily water output is?

2.5 liters of water

What are the two types of water outputs?

• Insensible water loss (we are unaware of the water loss)

  • Exhalation: 400 mL

  • Skin: 500 mL

• Sensible water loss (we are aware of it)

  • Urine: 1,500 mL

  • Feces: 100 mL

What comprises water input?

• Water from dietary gain + Metabolic production

• Our tissues produce around 300 mL of water/day through metabolic processes.

What is the Adequate Intake (AI) for humans?

• AI for adult males= 3.7 Liters (15.6 cups)

• AI for adult females= 2.7 Liters (11 cups)

These intakes are higher than the average intake of 2.2 liters. AI for water includes water from all dietary sources. People are not expected to consume 15.6 or 11 cups of pure water per day.

What is thirst?

An osmoregulatory mechanism to increase water input.

What happens to thirst in older people?

The thirst mechanism is not as responsive and therefore there is a higher risk for dehydration.

Which organs help regulate blood volume

Kidneys, hypothalamus, and adrenal glands.

What are the roles of electrolytes?

To maintain the water balance. (osmolarity)

What are two major electrolytes?

Sodium (Na)- major electrolyte in fluid OUTSIDE of cells

Potassium (K)- major electrolyte in fluid INSIDE of cells

NOTE: High sodium intake tends to pull fluid out of cells. High potassium intake tends to pull fluid into cells.

What are the functions of sodium?

• Plays a role in maintaining fluid balance and many other essential functions.

• Notable function is in nerve impulse transmission and muscle contraction.

• essential for nutrient absorption in the small intestine and also for nutrient reabsorption in the kidney. (sodium potassium pump)

What should be known regarding sodium absorption?

• Sodium absorption in the small intestine is extremely efficient and in a healthy individual all excess sodium is excreted by the kidneys.

• Very little sodium is required in the diet (abt. 200 mg) because the kidneys actively reabsorb sodium.

• Kidney reabsorption of sodium is hormonally controlled, allowing for a relatively constant sodium concentration in the blood.

Hypoatremia

Low blood sodium levels resulting due to excess sodium loss, drinking too much water, illnesses causing vomiting, sweating, and diarrhea.

What is the upper intake level (UL) for sodium?

2,300 mg per day for adults

Where are chloride protein channels most abundant?

In the GI tract, pancreas, and lungs.

What are the functions of chloride?

• Important function maintaining acid-base balance

• Proteins, such as albumin, as well as bicarbonate ions and chloride ions, are negatively charged and aid in maintaining blood pH.

• Hydrochloric acid (a gastric acid composed of chlorine and hydrogen) aids in digestion and also prevents growth of unwanted microbes in the stomach.

• Immune-system cells require chloride, and red blood cells use chloride anions to remove carbon dioxide from the body.

Cystic Fibrosis

One of the most prevalent inherited diseases in people of European descent. It is caused by a mutation in a protein that transports chloride ions out of the cell. Symptoms are:

• Salty skin

• Poor digestion and absorption (leading to poor growth)

• Sticky mucus accumulation in the lungs (increased susceptibility to respiratory infections)

• Liver damage

• Infertility

What can cause low blood levels of chloride?

Low dietary intake of chloride and more often diarrhea

What are the symptoms of a chloride imbalance?

similar to those of hyponatremia and include weakness, nausea, and headache. Excess of this electrolyte in the blood is rare with no characteristic signs or symptoms.

Potassium

The most abundantly positively charged ion inside of cells.

• 90% of potassium exists in intracellular fluid, with about 10 % in extracellular fluid, and only 1% in blood plasma.

• strictly regulated

• Hormone aldosterone is what primarily controls potassium levels, but other hormones (such as insulin) also play a role.

• Because potassium is required for maintaining sodium levels, and hence fluid balance, about 200 mg of potassium are lost from the body every day.

Hypokalemia

insufficient potassium levels in the body. Caused by a low dietary intake of potassium or by high sodium intakes. More commonly results from meds that increase water excretion, mainly diuretics. Signs and symptoms are:

• muscle weakness and cramps

• respiratory distress

• constipation

• severe potassium depletion can cause the heart to have abnormal contractions and can even be fatal.

Hyperkalemia

High levels of potassium in the blood. it affects the heart. It is a silent condition as it often displays no signs or symptoms. Extremely high levels of potassium in the blood disrupt the electrical impulses that stimulate the heart and can cause the heart to stop. Usually the result of kidney dysfunction.

What is the #1 cause of early-childhood death worldwide?

diarrhea-induced dehydration

What are some signs and symptoms of dehydration?

• Thirst

• dizziness

• fainting

• headaches

• low blood-pressure

• fatigue

• low to no urine output

• loss of consciousness and death

There is strong evidence that this condition can increase the risk for kidney disease, heart disease, and the development of hyperglycemia in people with diabetes. As well as kidney stones and exercise- induced asthma.

Older people often suffer from this condition since their thirst mechanism is no longer as sensitive as it used to be.

Heat stroke

A life-threatening condition that occurs when the body temperature is greater than 105.1 F (40.6 C).

It is a result of the body being unable to sufficiently cool itself by thermoregulatory mechanisms.

Dehydration is a primary cause of heat stroke as there are not enough fluids in the body to maintain adequate sweat production, and cooling of the body is impaired.

what are the signs and symptoms of heat stroke?

• Dry skin (absence of sweating)

• Dizziness

• Trouble breathing

• rapid pulse

• confusion

• agitation

• seizures

• coma

• possibly death

Dehydration may be preceded by heat exhaustion, which is characterized by heavy sweating, rapid breathing, and fast pulse.

The elderly, infants, and athletes are the most at risk for this condition.

Hypertension

The force of moving blood against arterial walls is much higher than normal. It is reported as the systolic pressure over the diastolic pressure, which is the greatest and least pressure on an artery that occurs with each heartbeat. Measured with a device called a sphygmomanometer. results are recorded in millimeters of mercury, or mmHg.

Normal range: 90/60- 120/80 mmHg.

Hypertension: 140/90 mmHg or greater

This condition is a risk factor for cardiovascular disease, and reducing blood pressure has been found to decrease the risk of dying from a heart attack or stroke.

Most drinking water is disinfected by the process of?

chlorination, which involves adding chlorine compounds to the water. Chlorine-resistant protozoa and viruses are instead removed by extensive filtration methods.

What is the primary anion in extracellular fluid?

Chloride