Water

Water constitutes about 65 -70 % total body weight

Fluid balance between ECF & ICF Products of digestion are absorbed in a

fluid medium and distributed in blood and lymph

Controlled body temperature Excretion (lung , kidney ,..) Involve chemical reaction

Water sources

Water is a constituent of most food , even though they may be solid in consistency:

Bread contains approximately 35% water

Fish 65% Meat 50-70% Vegetables and fruits 80-90%

Water balance

Water is lost from the body in urine , faeces , sweat and expired air.

The regulatory mechanisms in the kidneys result in a variable volume of urine being secreted-consequently a balance is maintained between intake and output of water

Requirement

An average adult living in a temperate climate requires approximately 2500 ml of water daily.

The actual amount that is ingested depends both on climate and habit :

Drinks provide 1000-2500 ml. Food provide 1000-1500 ml. Metabolism provide 200-400ml.

Dehydration

Means loss of water , but is often used as implying a loss of certain mineral elements also , particularly sodium.

Loss of up to 5% of body-weight by dehydration results in thirst and discomfort.

Loss of 6-10% results in dizziness , absence of saliva and inability to walk.

Loss of 11-12% results in delirium , swollen tongue , inability to swallow and shrivelled skin

Why Is Water So Important?

Water is the most abundant substance in the bodyAverage healthy adult is 50–60% water depending onAgePercent of water declines with ageComposition of fat and muscleMuscle is ~65% waterFat is 10–40% waterMale 60% and female 50%) )Gender

Most athletes and coaches are aware that will dehydration will result in a loss of performance .

Water is often referred to as the “silent nutrient” To maintain health , and both deficiency

symptoms and overdosage symptoms can be observed.

Water is a largest single component for about 50-60% 0f total body mass .

Lean body tissue contain a constant fraction – about 75% of water by mass , whereas adipose tissue has a little watter contant.

Why Is Water So Important?

Electrolyte content , and protein content , which will influence the volume of urine that must excreted.

The water formed by the oxidation of food stuffs will make some small contribution to meeting to daily water losses , but water in drinks and in foods will meet most the demand.

Losses in urine , faces , sweat , expired air and are the major avenues of water loss : smaller losses occur through blood loss , and in semen , tears , etc., but it was normally trivial

Why Is Water So Important?

The regulation of body water and electrolyte concentration involves a number of neural and hormonal mechanisms which influence both intake loss.

Social and other factors that act to increase or restrict fluid intake.

Why Is Water So Important?

Metabolic 400Water productionFluid 1600Water content of food 1000

Total 3000

Urine 1400 Expired air 320Skin loss 530Sweat loss 650Fecal loss 100

Total 3000

Fluid Balance

Water is essential for life, HOW???

Water is vital to health and normal cellular function as it is a medium for metabolic reactions within cells.Transporter for nutrients and waste products.Lubricant.

Help in regulating and maintaining body temperature.

Water

60% percent of male body weight 50% percent of female body weight Mostly in the intracellular fluid Water exchange between ICF and ECF occurs across

cell membranes by osmosis

Why this difference between males and females? In old age, only about 45% of body weight is water

The Composition of the Body

Functions of Water in the Body

Commonly known as a universal solvent Polarity allows it to attract charged particles into

solutions and dissolve a variety of other polar substances Important to digestion

Helps transport dissolved nutrients and other substances throughout the body

Blood is composed of water and red blood cells Water allows blood to transport oxygen, nutrients,

and hormones to cells Water helps transport waste products away from

cells to be excreted

Functions of Water in the Body 2

Lubricates joints, sensitive eye tissues, mouth, and intestinal tract

Provides a protective cushion, bathing certain organs with fluid During pregnancy the fetus is surrounded by

watery amniotic fluid Provides a structural component to cells

Figure 11.5

Water Balance between Fluid Compartments

Body fluid is located

• Intracellular – within the cells

• Extracellular – outside the cells

Control of water balance

Water intake and excretion are driven by a complex interaction of neural and hormonal factors which respond to a number of different inputs.

A rise or fall of about 5msmol /l in the plasma osmolality is sufficient to switch the kidney from maximum conservation of water to maximum urine output

Sodium has greatest effect on fluid balance(50% osmolality)

Body Fluid Compartments

2/3 (65%) of TBW is intracellular (ICF) 1/3 extracellular water

• 25 % interstitial fluid (ISF)

• 5- 8 % in plasma (intravascular fluid)

• 1- 2 % in transcellular fluids – CSF, intraocular fluids, serous membranes, and in GI, respiratory and urinary tracts (third space)

What are the factors that influence body fluids?

Major Compartments for Fluids

INTRACELLULAR FLUID (ICF)Inside cellMost of body fluid here - 63% weightDecreased in elderly

EXTRACELLULAR FLUID (ECF)Outside cell Intravascular fluid - within blood vessels (5%)Interstitial fluid - between cells & blood vessels (15%)Transcellular fluid - cerebrospinal, pericardial , synovial

ELECTROLYTES IN BODY FLUID COMPARTMENTS

INTRACELLULAR EXTRACELLULAR

POTASSIUM SODIUM

MAGNESIUM CHLORIDE

PHOSPHOROUS BICARBONATE

Movement of Body Fluids and Electrolytes

It can be by:

Osmosis?

Diffusion?

Filtration?Active

transport

METHODS OF FLUID & ELECTROLYTE MOVEMENT

1- Passive Transport

Diffusion Osmosis Filtration

2- Active Transport

using energy (ATP)

DIFFUSION

Process by which a solute ( ions and molecules) in solution moves as gas or substance

Molecules move from an area of higher concentration to an area of lower concentration to evenly distribute the solute in the solution

It can be simple or facilitated diffusion

FACILITATED DIFFUSION

Involves carrier system that moves substance across a membrane with simple diffusion , (from area of higher concentration to one of lower concentration)

Example is movement of glucose with assistance of insulin across cell membrane into cell

Figure 11.6

Osmosis

Electrolytes Participate in Fluid Balance

OsmosisStrongest factor influencing water balance between compartmentsWater moves from a diluted concentration to a more concentrated areaOsmolarity of a solution indicates total concentration

FILTRATION

Movement of fluid and solutes together through a selectively permeable membrane from an area of higher hydrostatic pressure to an area of lower hydrostatic pressure

Arterial end of capillary has hydrostatic pressure > than osmotic pressure so fluid & diffusible solutes move out of capillary

ACTIVE TRANSPORT SYSTEM

Moves molecules or ions uphill against concentration & osmotic pressure

Requires specific “carrier” molecule as well as specific enzyme (ATP)

Hydrolysis of adenosine triphosphate (ATP) provides energy needed

Sodium-potassium pump is an active transport system. It moves substances from area of low solutes concentration to a higher one

Homeostasis definition?

• The tendency of an organism or a cell to regulate its internal conditions, usually by a system of feedback controls, so as to stabilize health and functioning, regardless of the outside changing conditions

HOMEOSTASIS!!!

What is Homeostasis?

Homeostasis makes sure our body has the correct levels of;

Temperature

Carbon dioxide

OxygenWater

Homeostasis involves maintaining a

constant internal environment in the body

In Out

BreathSweatFaecesUrine

Food and drinkWater made in respiration

B2 : How does the body control water balance?

Our bodies need a balanced water level to keep the internal concentration of our cells at the correct level

for them to work properly.

The kidneys

Kidneys do two main jobs:

1. Remove waste urea from the blood.

2. Keep a balance of other chemicals in the blood – including water.

The kidneys can cover water and electrolytes by reducing the rate of loss , but can do nothing to store a deficit, which can only be corrected by fluid intake.

The subjective sensation of thirst initiates the desire to drink and hence plays a key role in the control of fluid balance.

Thirst relatively insensitive to acute changes in hydration status in humans, and the desire to drink is a powerful regulatory factor

A number of the sensations associated with thirst: Drinking behavior Dryness of the mouth or throat Distention of stomach

The thirst control centers in the brain play a key role in the regulation of both thirst and diuresis.

Changes in plasma osmolality and blood pressure and volume , while others are stimulated by the fluid balance hormones which also regulate renal excretion.

A rise of between 2 and 3 % in plasma osmolality from the normal level of about 280- 295 msmol/l

Is sufficient to evoke a profound sensation of thirst coupled with an increase in the circulating concentration of ADH

Homeostatic Mechanisms

Kidneys:The kidneys are functioning under the

mastering of aldosterone and antidiuretic hormone (ADH).

Regulate electrolytes levels in the ECF by selective retention of needed substances and excretion of unneeded substances.

Regulate pH of ECF by excretion or retention of hydrogen ions.

 

Antidiuretic Hormone (ADH)

Stimulates water conservation at kidneys:

• reducing urinary water loss

• concentrating urine Stimulates thirst center:

• promoting fluid intake

ADH Production

Osmoreceptors in hypothalamus monitor osmotic concentration of ECF (plasma, CSF)

Change in osmotic concentration in plasma and CSF alters osmoreceptor activity

Osmoreceptor neurons secrete ADH in proportion to osmotic concentraiton via the posterior pituitary

Aldosterone

Is secreted by adrenal cortex in response to:• rising K+ (sensed at the adrenal cortex) or falling

Na+ levels in blood

• activation of renin–angiotensin system (usually due to changes in blood volume)

Determines rate of Na+ absorption and K+ loss along DCT and collecting system

“Water Follows Salt” • High plasma aldosterone concentration causes

kidneys to conserve salt

• Conservation of Na+ by aldosterone also stimulates water retention

Figure 26.8

Ald

oste

rone

Figure 11.8

Blood Volume Regulates Blood Pressure

Water content of the blood normal

Water content of the blood HIGH

Water content of the blood LOW

Too much water drunk

Too much salt or sweating

Brain producesMore ADH

Urine output LOW

Brain produces Less ADH

Urine output HIGH

High volume of waterreabsorbed by kidney

Low volume of waterreabsorbed by kidney

(small volume of Concentrated urine)

(large volume of dilute urine)

Normal blood concentration

Blood too concentrated – detected in brain

ADH secreted by pituitary gland

ADH causes kidneys to reabsorb more water to blood

Normal blood concentration

Blood too dilute – detected in brain

ADH not secreted by pituitary gland

kidneys reabsorb less water to blood

Water Balance

Natriuretic Peptides

ANP and BNP are released by cardiac muscle cells in response to abnormal stretching of heart walls due to elevated blood pressure or volume

• Reduce thirst

• Block release of ADH and aldosterone

• Cause diuresis

• Lower blood pressure and plasma volume

FLUID VOLUME DEFICIT (FVD)

Hypovolemia or FVD is result of water & electrolyte loss

Compensatory mechanisms include: Increased sympathetic nervous system stimulation with an increase in heart rate & cardiac contraction; thirst; plus release of ADH & aldosterone

Severe case may result in hypovolemic shock or prolonged case may cause renal failure

Disorders of Water Balance:

Figure 26.7a

Several factors will influence the body water losses and thus determine the requirement for water intake

Ambient climatic condition Level of physical activity Body size Body composition & volume Metabolically activity Body surface area

FLUID VOLUME DEFICIT (FVD)

Hypovolemia or FVD is result of water & electrolyte loss

Compensatory mechanisms include: Increased sympathetic nervous system stimulation with an increase in heart rate & cardiac contraction; thirst; plus release of ADH & aldosterone

Severe case may result in hypovolemic shock or prolonged case may cause renal failure

SIGNS & SYMPTOMS OF FVD

Dry mucous membranes Weight loss Orthostatic hypotension & tachycardia Subnormal Body temperature Flat neck veins & decrease in CVP Decreased urinary output & altered

sensorium

Dehydration !!!!

Water isn’t replaced in body Fluid shifts from cells to EC space Cells lose water Happens in confused, comatose, bedridden persons

along with infants & elderly May be treated with hypotonic sol (like dextrose 5%

in water)

Signs of Dehydration

Dehydration Causes

Risk Factors Insufficient intake due to anorexia, nausea, impaired

swallowing, confusion, depression.

Loss of water and electrolytes from: vomiting, diarrhea, nasogastric suction, excessive sweating, fever, polyuria, abdominal drainage, or wound losses.

FLUID VOLUME EXCESS (FVE)

FVE is a result of expansion of fluid compartment due to increase in total sodium content .

Fluid excess in the intravascular space is called hypervolemia.

Fluid excess in interstitial space is called edema Excess of extra cellular fluid in other body

compartment Third space is called. Fluids may be trapped in abdomen, peritoneum (ascites) or plural space (plural effusion).

SIGNS & SYMPTOMS OF FVE

Orthopnea Edema & weight gain Distended neck veins & tachycardia Increased blood pressure Crackles & wheezes May be ascites & pleural effusion Increase in CVP

EDAEMA

It is excessive accumulation of fluid in the interstitial space it may be

localized edema if it due to trauma or inflammation.

Generalized edema involves the whole body. It is severe.

Pitting edema on the leg Pitting edema on the foot

Pitting odema

Water Intoxication !!!!

Excess fluid moves from EC space to IC space

Happens with SIADH, rapid infusion of hypotonic IV sol or tap water as NG irrigant or enemas; can happen with psychogenic polydipsia ( may drink 12-18 L/day )

Findings Serum NA < 125 mEq/L Serum Osmolality < 280 mOsm/kg

Electrolyte Balance An electrolyte balance exists when the

quantities of electrolytes gained equals the amount lost.

• Electrolyte Intake

- The electrolytes of greatest importance to cellular metabolism are sodium, potassium, calcium, magnesium, chloride, sulfate, phosphate, bicarbonate, and hydrogen ions.

- Electrolytes may be obtained from food or drink or produced as a by-product of metabolism.

Electrolyte Balance

• Regulation of Electrolyte Intake

- A person ordinarily obtains sufficient electrolytes from foods eaten.

- A salt craving may indicate an electrolyte deficiency.

• Electrolyte Output

- Losses of electrolytes occur through sweating, in the feces, and in urine.

Electrolyte Imbalances

1. Sodium– Hyponatremia– Hypernatremia

2. Potassium– Hypokalemia– Hyperkalemia

3. Calcium– Hypocalcemia– Hypercalcemia

4. Magnesium– Hypomagnesemia– Hypermagnesemia

5. Phosphorus– Hypophosphatemia– Hyperphosphatemia

Calcium

More than 99% of total body calcium is stored in the bones and teeth where it functions to support their structure. The remaining 1% is found throughout the body in blood, muscle, and the fluid between cells.

function

Calcium is also critical for the normal transmission of nerve impulses. Calcium flows into nerve cells and stimulates the release of molecules called neurotransmitters.

Calcium also plays the role in muscle contraction, healthy blood pressure, the initiation of blood clotting, and the regulation of various hormones and enzymes.

Food Sources:

• Best sources: milk and milk product; • Good sources: beans, vegetables, fish,

cabbage,broccoli

Three Forms of Circulating Ca2+

Calcium Balance

Intake = output Negative calcium balance:

Output > intake

• Neg Ca2+ balance leads to osteoporosis

Positive calcium balance: Intake > output

• Occurs during growth Calcium is essential, we

can’t synthesize it

Calcium and the Cell

Translocation across the plasma membrane Translocation across the ER and mitochondrion; Ca2+

ATPase in ER and plasma membrane

Anatomy and Feedback Inhibition

Regulation of PTH Secretion and Biosynthesis

Extracellular Ca 2+ regulates secretion of PTH

• Low Ca 2+ increases

• High Ca 2+ decreases Ca2+ also regulates transcription High levels of 1,25 dihydroxyvitamin D3

inhibit transcription

Calcitonin

• This decreases serum Ca2+ Promotes renal excretion of Ca2+ Probably not essential for human survival Potential treatment for hypercalcemia

Transport and Metabolic Sequence of Activation of Vitamin D

Vitamin D-dependent Ca2+ Absorption

Duodenum>jejunum>ileum Absorption is greater at low pH

• The pH of the stomach is about 2

• Peak absorption at the beginning of the duodenum

Sequence of Adjustments to Hypocalcemia

SODIUM (NA)*

Normal Serum [Na] (135-145 mEq/L) Main extracellular fluid (ECF) cation

Influences water distribution (with chloride)

Sodium Functions

Transmission and conduction of nerve impulses Responsible for osmolarity of vascular fluids Regulation of body fluid levels Sodium shifts into cells and potassium shifts out of

the cells (sodium pump) Assists with regulation of acid-base balance by

combining with Cl or HCO3 to regulate the balance

MAGNESIUM

Magnesium is a cofactor in more than 300 enzyme systems that regulate diverse biochemical reactions in the body, including protein synthesis, muscle and nerve function, blood glucose control, and blood pressure regulation

Food Sources

Green vegetables such as spinach because the center of the chlorophyll molecule(which gives green vegetables their color)

Legumes(beans and peas) Nuts and seeds

Daily Requirement

ADULT MEN 19 to 30 400mg 31 yrs and older 420mg ADULT WOMEN 19 to 30 310mg 31 yrs and older 320mg

Approximately 30% to 40% of the dietary magnesium consumed is typically absorbed by the body

Typical magnesium absorption involves: 40% of magnesium intake absorbed in the small

intestine 5% absorbed in the large intestine 55% leaving the body as waste

Potassium

Dominant cation in intracellular fluid (ICF)

Serum potassium3.5 – 5 mmol/L

K+ intake 4700mg from vegetable and fruit

K+ excretion:

Kidney : approximately 90% of dietary potassium

GI tract: only about 10 % Major organ of excretion potassium: kidney

Regulative site: renal distal tubule

Factors of affecting renal handling potassium

Aldosterone Activates Na+-K+ ATPase Sodium channels in the luminal membrane Na+reabsorption

Potassium channels in the luminal membrane

Intracellular potassium content Secretion

Urine flow rate Secretion

Distal delivery of sodium Secretion

Acid-base balance: Acute acidosis Secretion

2) Balance of potassium distribution: It is depended Na+—K+—ATPase on the cellular

membrane(pump leak). consumption of 1 ATP→pumping 3 Na+ out off

and 2 K+ into the cell Total body potassium approximately 98% in ICF

50-55mmol/kg B.W approximately 2% in ECF

ICF (3500mmol ): 150-160mmol/L ECF (70 mmol ): serum potassium 3.5-5.5mmol/L

Phosphorous (P)

How is P used in organisms? Biomolecules

• ADP and ATP

• nucleic acids

• phospholipids (cell membranes)

• apatite (bones and tooth 80%)

Serum Phosphorous 2.4– 4.6 mgl/dL Food Sources: meat & milk

Acid-Base Balance

7.35-7.45

Definitions Acid: is a substance that can donate hydrogen

ions in solution.

Strong acid such as hydrochloric acid (HCl)release all the H+.

Weak acids like carbonic acid (H2CO3) release some H+.

Base or Alkali: is a substance that can accept hydrogen ions in solution.

Acidity or alkalinity is measured by pH.

ACID-BASE BALANCE

Definitions 2

pH: means the concentration of hydrogen ions [H+] of the solution.

In the body, weak acids and weak bases regulate acid-base balance to prevent sudden changes in the pH of the body fluids.

Normal pH= 7.35 – 7.45. <7.35 = acidosis, >7.45 = alkalosis

ACID-BASE BALANCE

Governed by the regulation of hydrogen ion (H+) concentration in the body

pH = negative logarithm of the H+ concentration Acids - proton donors & give up H+ Bases - H+ acceptors Acidic - inc. in concentration of H+ Basic - dec. in concentration of H+

Regulation of Acid-Base Balance

Normal Values:

pHpH PCO2PCO2 HCO3HCO3

7.35 – 7.457.35 – 7.45 35 – 45 mm Hg35 – 45 mm Hg 22 – 26 mEq / L22 – 26 mEq / L

Acid – Base Balance

Acid Base Balance

Arterial Blood Gases (ABGs)

Arterial Blood Gases (ABG)

pH 7.35-7.45 PaCO2 35-45 mm

Hg Pa O2 80-100 mm

Hg O2 sat. 95-99% HCO3- 22-26mEq/L

Acid-Base Balance• The Respiratory Center

- The respiratory center in the brain stem helps to regulate hydrogen ion concentration by controlling the rate and depth of breathing.

- During exercise, the carbon dioxide, and thus the carbonic acid, levels in the blood increase.

- In response, the respiratory center increases the rate and depth of breathing, so the lungs excrete more carbon dioxide.

Acid-Base Balance

• The Kidneys

- Nephrons secrete excess hydrogen ions in the urine.

Acid-Base Imbalances Chemical and physiological buffer systems usually

keep body fluids within very narrow pH ranges but abnormal conditions may prevent this.

CHEMICAL BUFFER SYSTEMS - bicarbonate, phosphate, protein, hemoglobin

LUNGS - carbonic acid broken down into CO2 & H2O KIDNEYS - increasing or decreasing bicarbonate ions

Acid-Base Imbalances Acidosis

• Two major types of acidosis are respiratory and metabolic acidosis.

- Respiratory acidosis results from an increase of carbonic acid caused by respiratory center injury, air passage obstructions, or problems with gas exchange.

- Metabolic acidosis is due to either an accumulation of acids or a loss of bases and has many causes including kidney disease, vomiting, diarrhea, and diabetes mellitus.

Acid-Base Imbalances

• Increasing respiratory rate or the amount of hydrogen ions released by the kidney can help compensate for acidosis.

Respiratory Acidosis*

pH < 7.35 PaCO2 > 45mm Hg Due to inadequate alveolar ventilation Tx aimed at improving ventilation Respiratory Opposite

Respiratory Alkalosis*

pH > 7.45 PaCO2 < 35mm Hg Due to alveolar hyperventilation & hypocapnia Tx depends on underlying cause

Metabolic Acidosis*

pH < 7.35 HCO3 < 22mEq/L Due to gain of acids or loss of base (like excessive GI

loss from diarrhea) May have associated hyperkalemia Tx aimed at correcting metabolic defect Metabolic Even

Metabolic Alkalosis*

pH > 7.45 HCO3 > 26 mEq/L Due to loss of acid or gain of base (most common is

vomiting or gastric suction) Hypokalemia may produce alkalosis Tx aimed at underlying disorder

Respiratory acidosis

Risk Factors Clinical Manifestation Nursing Intervention

•Acute lung disease: pneumonia, acute pulmonary edema, aspiration of foreign body…•Chronic lung disease: asthma, cystic fibrosis, emphysema•Overdose of narcotics•Brain injury•Airway obstruction•Chest injury

•Increased pulse•Increased respiratory rate•Headache•Confusion•Convulsions•Warm flushed skin

•Assess respiratory status and lung sound•Monitor air way and ventilation•Inhalation therapy•Percussion and postural drainage•Monitor fluid intake and output•Measure vital signs•Measure arterial blood gases

Respiratory alkalosisRisk Factors Clinical Manifestation Nursing Intervention

•Hyperventilation due to:-Extreme anxiety-Elevated body temp.-Overventilation-Hypoxia-Salicylate overdose

•Brain energy•Fever•Increased basal metabolic rate

•Shortness of breath•Chest tightness•Numbness and tingling of extrimities•Difficulty concentrating•Blurred vision

•Monitor vital signs and ABGs•Assist client to breath more slowly•Help client breath in a paper bag

Metabolic acidosis

Risk Factors Clinical Manifestation

Nursing Intervention

•Increase of non volatile acids in blood:-renal impairment-DM•Decrease in bicarbonates:-Prolonged diarrhea•Excessive NaCl infusion•Salicylates overdose•Cardiac arrest

•Deep rapid respiration•Lethargy, confusion•Headache•Weakness•Nausea and vomiting

•Monitor ABG values•Monitor intake and output•Monitor of LOC•Administer IV sodium bicarbonate

Metabolic alkalosisRisk Factors Clinical

ManifestationNursing Intervention

•Excessive acid base due to:-Vomiting-Gastric suction•Excessive use of K-losing diuiretics•Excessive adrenal corticoid hormones due to:-Cushing’s syndrome-Hyperaldosteronism•Excessive bicarbonate intake from:-Antacids-Parenteral NaHCO3

•Increase respiratory rate and depth•Dizziness•Numbness and tingling of the extremities•Hypertonic muscles, tetany

•Monitor intake and output•Monitor vital signs especially respiration and LOC•Administer IV fluid carefully

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