Lecture 18 - Body Fluids and Blood Flashcards
What percentage of the body is water?
60%
What percentage of the body is minerals?
7%
What percentage of the body is protein?
18%
What percentage of the body is fat?
15% but more in females
Water is a ________ for many chemicals of the body.
Solvent
The solutions formed by water and body chemicals provide…
Media for the body cells to receive and expel materials
What are the physical properties of water that make it ideal for transport?
- High specific heat
- Provides lubrication
List the body’s fluid compartments.
- Intracellular fluid
- Extracellular fluid (2 parts)
- Interstitial fluid
- Plasma
Where is most of the body water found?
Cells (intracellular fluid)
What percentage of total body weight is from the water in intracellular fluid?
40%
What percentage of total body weight is from the water in extracellular fluid?
20%
What is the relative volume of water in ECF compartments?
Plasma 20% of ECF
Interstitial fluid 80% of ECF
How many litres of water are in the body?
40L
How many litres of water are in plasma?
3L
How many litres of water are in interstitial fluid?
12L
How many litres of water are in intracellular fluid?
25L
What are the 2 main fluid compartments?
- Intracellular fluid compartment (ICF)
- Extracellular fluid compartment (ECF)
Which organic substances are in body fluids?
Glucose
Amino acids
Fatty acids
Hormones
Enzymes
Which inorganic substances are in body fluids?
Sodium
Potassium
Calcium
Magnesium
Chloride
Phosphate
Sulphate
What is interstitial fluid?
-Fluid between cells
-Consists of water solvent containing organic and inorganic material
What does the composition of tissue fluid depend on?
The exchanges between the cells in the tissue and the blood
What else does interstitial fluid do?
-Medium of interchange between blood and intracellular environment
-Acts as a media for intercellular communication
What separates ICF from interstitial fluid?
Cellular membrane
What separates interstitial fluid from blood?
Blood vessel walls
What are the major sources of water input?
Metabolism - 10%
Foods - 30%
Water intake - 60%
What are the major sources of water output?
Feces - 4%
Sweat - 8%
Skin and lungs - 28%
Urine - 60%
What are some conditions that can affect water loss?
-Environmental temperature
-Skin barrier interruptions (burns)
-Exercise
-Diarrheal diseases
-Renal diseases
What are the 2 driving forces of water movement?
- Osmotic pressure
- Hydrostatic pressure
What is osmotic pressure?
The amount of hydrostatic pressure required to stop osmosis from moving water from low to high concentration across a cell membrane (High concentration = high osmotic pressure)
What will happen to a cell put into a hyperosmotic solution?
Water will flow OUT of the cell
What will happen to a cell put into a hyposmotic solution?
Water will flow INTO the cell
What are 2 methods of body fat estimation?
- Bioelectrical impedance analysis
2.Deduction
What is bioelectrical impedance analysis?
Using the resistance of flow of a small current between points on the body to estimate body fat amount, since fat does not conduct electricity
What is deduction?
Calculating fat mass from total body mass - lean body mass
What are 3 disorders of water balance?
-Dehydration
-Hypotonic hydration
-Edema
What is hypotonic hydration?
Cellular over-hydration, which causes cells all over the body to swell and lyse. Also affects RBC’s oxygen carrying ability.
What is edema?
Accumulation of interstitial fluid in tissues due to increased fluid out of blood or decreased fluid into blood
What do all of the ions in the body contribute to?
The osmotic balance that controls the movement of water between cells and their environment
What is the major cation and anion of ECF?
Cation: Na+
Anion: Cl-
What is the major cation and anion of ICF?
Cation: K+
Anion: PO4(3-) - Phosphate
What can changes in Na+ levels affect?
Plasma volume
Blood pressure
ECF and ICF volumes
Why is K+ important?
Contributes to the resting membrane potential in neurons and muscle fibers
What is hyperkalemia and what can happen from it?
Increased K+ levels
-Impairs function of skeletal muscles, nervous system, heart
-Heart won’t relax and stay contracted, which is fatal
What role does Cl- play in ECF?
Maintains proper hydration and electrical neutrality
What is the function of bicarbonate in the blood?
To act as a buffer to maintain body’s acid-base balance
What percent of of CO2 is converted to bicarbonate?
90%
What is calcium important for in the body?
Muscle contraction
Enzyme activity
Blood coagulation
Release of neurotransmitters/hormones
What gets activated to allow calcium to be absorbed through the intestines?
Vitamin D
What is phosphate important for?
-Calcium-phosphate salts in bone and teeth
-Phospholipids in cell membranes
-Found in ATP, nucleotides, buffers
What is the normal pH of arterial blood?
7.4
What is the normal pH of venous blood and interstitial fluid?
7.35
What is the normal pH of ICF?
7.0
Why is venous blood pH lower than arterial blood pH?
The tissues produce CO2 that dissolves in water to form carbonic acid, which lowers the pH slightly
What is the difference between a strong acid and a weak acid?
A strong acid will dissociate completely in water, a weak acid will not
What is the role of a buffer in blood?
Permits blood to maintain a narrow pH range even when disturbances occur
What will a weak acid absorb?
Hydroxyl ions
What will a weak base absorb?
Hydrogen ions
What is the order (in terms of time taken to have an effect) of hydrogen ion regulation in the body?
- Chemical buffer systems
- Brainstem respiratory centers
- Renal mechanisms
How can proteins act as buffers?
Charged regions of protein molecules bind to hydrogen and hydroxyl ions
How does hemoglobin function as a buffer?
CO2 that has been turned into bicarbonate will release a hydrogen ion, which is then buffered by hemoglobin
What is the function of carbonic anhydrase?
In blood cells - to force the dissociation of the acid and make the blood less acidic
What two forms is phosphate found in within blood?
- Sodium dihydrogen phosphate (NaH2PO4 - weak acid)
- Sodium monohydrogen phosphate (NaHPO4- weak base)
How does phosphate act as a buffer?
Phosphate as a weak acid or weak base binds to a strong acid or strong base to produce water and a weak acid/base
What is the primary buffering system of IF?
Bicarbonate-carbonic acid buffer
What are most of the body’s metabolic wastes?
Acids (lactic acid, ketone bodies)
What happens when the CO2 levels in your blood rise? (like when u hold ur breath)
Excess CO2 reacts with water to form carbonic acid, which lowers blood pH and gives you the urge to inhale (respiratory acidosis)
What happens to blood pH during hyperventilation?
CO2 levels decrease, which reduces levels of carbonic acid and increases pH (respiratory alkalosis)
What are some causes of metabolic acidosis?
-Increased acid production
-Acid ingestion
-Decreased renal acid excretion
-GI or renal HCO3- loss
What is diabetic ketoacidosis?
Not enough insulin to control blood glucose levels, which creates ketone bodies from fat. This increases the acidity of the blood.
How can an overdose of aspirin cause poisoning?
The metabolite of aspirin is acidic, so large doses can cause acidosis
What is a cause of metabolic alkalosis?
Hydrochloric acid loss from stomach through vomiting
What conditions can lead to respiratory acidosis?
Pnuemonia
Heart failure
How can aspirin overdose cause respiratory alkalosis?
The body will try to compensate for the acidosis by increasing ventilation, leading to alkalosis
