BSC 216 Exam #3: Fluid, Electrolyte, Acid & Base Homeostasis

What is Body Fluid?

The term used to encompass all of the body’s water-based liquids (blood plasma, interstitial fluid, cytosol, cerebrospinal fluid, lymph, exocrine secretions)

What is Fluid Balance?

The study of maintaining appropriate volume and concentration of the body’s intracellular and extracellular fluids

What are Electrolytes?

Substances that dissociate into ions when placed into water

Nonelectrolytes generally have what kind of bond?

Covalent Bonds

What is an Ion?

Something that differentiates electrolyte from of an element from its atomic metal form

What is an Acid?

A chemical that dissociates in water to release a H+ Ion (Common Acid: HCl)

What is a Base?

A chemical that accepts a H+ Ion into a solution (Common Base: HCO3-)

What does the pH scale measure?

H+ Ion Concentration

What is Total Body Water?

A reference volume that uses a “standard man” of 70 kg/154 lbs

What are the (2) Fluid Compartments?

Intracellular & Extracellular Compartment 

What is The Intracellular Compartment?

Composed of trillions of cells and their cytosol, or intracellular fluid (60%)

What is The Extracellular Compartment?

Filled with extracellular fluid composed of various body fluids (8% blood plasma, 32% interstitial fluid)

Which component of The Extracellular Compartment has higher protein content?

Blood Plasma, accounting for the main difference

What is Hydrostatic Pressure Gradient?

A force that fluid exerts on cells

What is Osmotic Pressure Gradient?

A force of solutes in a solution

High Hydrostatic/Osmotic Pressure dominates arteriolar/venular end of blood vessels:

Hydrostatic: Arteriolar 

Osmotic: Venular

What is Toncity?

A measurement of osmotic pressure gradient between two fluid components

Hypotonic vs Hypertonic:

Hypotonic: Cells with higher osmotic pressure pull water into cell and causes swelling

Hypertonic: Cells with lower osmotic pressure push water out of cell resulting in shriveled/shrinking

How is the majority of water loss excreated?

Urine via the Kidneys

(3) Factors of Water Loss:

1) Obligatory Water Loss: Loss through daily urine production

2) Sensible Water Loss: Water loss in daily feces excretion

3) Insensible Water Loss: Water loss through skin by sweat and evaporation

(2) Factors of Water Gain:

1) Metabolic Water: Water formed by Catabolic reactions

2) Ingested Water: Water enters body via food and liquid

What controls The Thirst Mechanism?

Ingested Liquids by Osmoreceptors in the Hypothalamus

What is the result of the Renin-Angiotensin-Aldosterone System?

Angiotensin-II

What hormone plays the most important role in Fluid Balance?

Antidiuretic Hormone (ADH)

*Produced by Hypothalamus, Released  by Posterior Pituitary Gland

What is the function of Angiotensin-II?

Promotes the reabsorption of Sodium and Chloride from the Proximal Tubule

What is the function of Aldosterone?

Stimulates the transcription of more sodium/potassium pumps and sodium-ion channels by kidney tubule cells

What is the function of Atrial Natriuretic Peptide?

Enhances the excretion of Sodium ions by Kidney tubule cells

What is Dehydration?

Decreased volume and increased osmolarity of ECF

What are a few causes of Dehydration?

Excessive Sweating, Diarrhea, Vomiting, Endocrine Conditions, Diuretic Overuse

What is Overhydration?

When the EFC volume increases, the osmotic pressure decreases, water enters cells causing swelling—caused by: extreme water intake in short period of time

What is Hypovolemia?

Fluid depletion caused by blood loss

What is Hypervolemia?

Excess fluid when EFC volume increases without change in osmotic pressure

What is Edema?

Swelling caused by fluid accumulation

True or False: The most abundant extracellular cation is about 135-145 mEq/L

True

*Depolarization Phase 

Regulation of which ion is critical in fluid balance?

Sodium Ion

Which (2) Hormones increase Sodium Ion Retention?

Angiotensin-II & Aldosterone

Which hormone decreases Sodium Ion Reabsorption?

Atrial Natriuretic Peptide

What is Hypernatremia?

When Sodium concentration goes above 145 mEq/L: Dehydration

What is Hyponatremia?

When Sodium concentration goes below 135 mEq/L: Overhydration

True or False: The most abundant intracellular cation lies at 139 mEq/L

True

*Repolarization Phase

*Extracellular Concentration: 3.9-4.5 mEq/L

Which ion regulation is essential for Endocrine & Urinary System control?

Potassium Ion

What is Hyperkalemia?

When Potassium concentration is greater than 4.5 mEq/L

What is Hypokalemia?

When Potassium concentration is lower than 3.9 mEq/L

Ca2+ and PO43- are bound together in?

Hydroxyapatite crystalline structure of osseous tissues

True or False: Calcium is maintained in plasma between 8.7-10.4 mg/dl

True

Which hormone is released in response to decreased Calcium content in the blood?

Parathyroid Hormone (PTH)

What occurs when EFC Calcium levels drop?

Calcium is released by Osteoclasts, reabsorbed from filtrate in kidneys and more readily from ingested food and liquids 

What occurs when EFC Calcium levels rise?

Calcium is deposited into the bone tissue by Osteoblasts and les sis reabsorbed from filtrate and ingested food 

What is Hypercalcemia?

When plasma Calcium concentration is above 10.4 mg/dl

What is Hypocalcemia?

When plasma Calcium concentration is below 8.7 mg/gl

*When case is severe neurons begin firing spontaneously

*Levels blow 4 mg/dl is considered lethal

What is normal body pH range?

pH: 7.35-7.45

What is The Chemical Buffer System?

A chemical system that buffers body fluids

What is The physiological Buffer System?

A system that relies on function of organs to buffer the fluids

What is the main source of Metabolic Acids?

Carbon Dioxide 

Which (2) Systems aid in maintaining blood pH?

Chemical & Physiological Buffer Systems

What is a Fixed Acid?

An acid that is unable to change into a gaseous state, therefore it must be eliminated by the kidneys

What is the most important Buffer System in the Blood?

Carbonic Acid Bicarbonate Ion Buffer System

How does the Respirator & Urinary System contribute to regulation of blood pH?

The Respiratory System controls amount of volatile acids in ECF while the urinary system controls the amount of fixed acids and bicarbonate ions in the ECF

Where does the formation of new Bicarbonate Ions occur?

Proximal Tubule Cells

What actively transports H+ into filtrate?

Intercalated Cells

What is an Acid-Base Imbalance?

A situation when compensatory mechanisms are unable to cope with additional acids/bases

Define Acidosis:

When the body’s fluid pH is less then 7.35

Define Acidemia/Alkalemia:

Low/High Blood pH

Define Alkalosis:

When the body’s fluid pH is more than 7.45

What is the use of Arterial Blood Gases (ABGs)

A clinical took used to assess and monitor a patients acid-base balance

Define conditions of Respiratory Alkalosis:

Increased pH & Decreased PCO2

Define conditions of Metabolic Alkalosis:

Increased pH & Increased HCO3-

Define conditions of Respiratory Acidosis:

Decreased pH & Increased PCO2

Define conditions of Metabolic Acidosis:

Decreased pH & Decreased HCO3-