Body Fluid Balance

Intracellular fluid

fluid inside cells

Intracellular fluid is what up of

water and electrolytes

Intracellular contains ____ % of body water

63

Too much water in tissue=

sweating

Extracellular fluid

fluid outside cells

Extracellular fluid contains ___% of body water

37

Types of extracellular fluid (3)

• interstitial fluid

• Blood plasma

• lymph

interstitial fluid located in

tissue spaces

Blood plasma located in

blood vessels

lymph located in

lymphatic vessels

Body fluid composition

water and electrolytes

Extracellular fluids are high in concentrations of what ions (4)

• Na⁺

• Cl^-

• Ca²⁺

• HCO₃^-

Intracellular fluid has high concentrations of what ions (2)

• K⁺

• Mg⁺²

Movements of fluid between compartments (2)

• Hydrostatic pressure

• Osmotic pressure

Hydrostatic pressure remains ____ and ____ in cells and interstitial fluid

equal; stable

Hydrostatic pressure is determined by (2)

Blood pressure and blood volume

Osmotic pressure: exerted by

impermeant solutes

Most fluid movement results from changes in

osmotic pressure

Water intake is controlled by the

thirst centers in the brain

Water output is controlled by the

kidneys and sweat

When the body loses as little as 1% of its water —> ___ osmotic pressure of ____ fluid

increase; extracellular

The increased osmotic pressure stimulates the ____ in the ____ causing the person to feel ____

osmoreceptors; hypothalamus; thirsty

When a person starts to feel thirsty ____ is absorbed by ____ and ___

water; stomach; small intestine

When water is absorbed the osmotic pressure of ______ fluid returns to ____

extracellular; normal

What hormone is most important for water balance

ADH

During dehydration extracellular fluid is

concentrated

During dehydration osmotic pressure is

increased

During dehydration osmoreceptors stimulate

ADH secretion

During dehydration ADH ______ reabsorption and conservation of water

increases.

After drinking excess water extracellular fluid is _____ concentrated

less

After drinking excess water osmotic pressure

decreases.

After drinking excess water decreased osmotic pressure ____ ADH secretion

inhibits

After drinking excess water, water reabsorption ______ and urine volume ____

decreases; increases.

Increased ADH —→ ____ osmotic pressure

increases

High ADH ——> ____ Blood Na⁺

decreases

Low ADH ——> _____ Blood Na⁺

increases

Normal blood K⁺

3.5 -5.0 mEq/L

Normal blood Na⁺

135-145

Electrolyte Intake (5)

• Na⁺

• K⁺

• Ca⁺²

• HCO₃^-

• H⁺

Aldosterone reabsorbs ___ and excretes ____ in the kidney

Na⁺, K⁺

Increased Aldosterone causes a blood Na⁺ ___

increase.

Increased Aldosterone causes a blood K⁺_____

decrease.

Decreased Aldosterone causes a blood Na⁺ ______

decrease.

Decreased Aldosterone causes a blood K⁺ ______

increase.

Calcitonin is secreted by

thyroid gland

Calcitonin to ____ serum Calcium and phosphate

decrease

Calcitonin ____ osteoclasts (bone absoprtions)

inhibits

Calcitonin ___ osteoblasts (bone formation)

activates

Calcitonin ____ the excretion of Ca and P in the kidney

increases

Parathyroid Hormone (PTH) to _____ serum calcium and ____ phosphate

increase, decrease

The Parathyroid Hormone (PTH) ____ osteoclast and ____ osteoblasts

activates, inhibits

Parathyroid Hormone (PTH) _____ Ca but ____ P in the kidney

reabsorbs; excretes

Parathyroid Hormone (PTH) increase ______ of Ca and P with the help of vitamin D in the intestines

absorption

Normal Blood pH

7.35-7.45

Acidosis

pH < 7.35

Alkalosis

pH > 7.45

What are Buffers?

chemicals which act to resist pH changes.

Chemical Buffer 1st line consists of

Bicarbonate Buffer system

Physiological buffer 2nd line is composed of (2)

• respiratory (CO₂ excretion)

• renal (H-ion excretion)

COPD: difficulty breathing ____

out

In COPD CO₂ _____

accumulates

In COPD there is _____ CO₂ which causes respiratory _____

increases; acidosis

in response to acidosis the acidosis the kidneys ____ the secretion of ____

increase; hydrogen ions

hyperventilation: _____ release of CO₂ ——> which leads to _____ CO₂ in blood

increase; decrease

Decreased CO₂—> respiratory _____

alkalosis

In response to alkalosis the kidneys ____ the secretion of _____

decrease; H-ion

DKA —> ______ keto-acid in blood

increased

increased keto-acid in blood —>

metabolic acidosis

in response to metabolic acidosis the lungs ____ ventilation which ____ CO₂ which ____CO₂

increase; remove; decrease

Term for decreased sodium

hyponatremia

Term for increased sodium

hypernatremia

Term for decreased potassium

hypokalemia

Term for increased potassium

hyperkalemia