Body Fluids and Blood

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Questions and Answers

What percentage of a 70kg young man's body is composed of water?

70%

40%

50%

60% (correct)

What percentage of total body water is composed of interstitial fluid?

15% (correct)

55%

40%

What is the primary function of plasma proteins in the body?

To regulate body temperature

To produce hormones and enzymes

To maintain blood pressure

To facilitate transport and regulate osmolarity (correct)

Which of the following ions is NOT a major ion in body fluids?

Fe2+ Signup and view all the answers

Which of the following is NOT a key concept in understanding body fluid compartments?

Blood pressure Signup and view all the answers

What is the term for the process of measuring body fluid compartments?

Spaces measurement Signup and view all the answers

Why must the osmolarity of ICF and ECF be equal?

To prevent cell swelling or shrinkage Signup and view all the answers

What determines osmotic pressure in a solution?

Total number of freely diffusible entities Signup and view all the answers

Which of the following is an example of a type of blood cell?

Platelet Signup and view all the answers

What is the primary function of capillaries in the body?

To facilitate exchange of molecules across membranes Signup and view all the answers

What percentage of total body water is composed of plasma?

5% Signup and view all the answers

What are the major constituents of body fluids?

Ions, proteins, dissolved gases, nutrients, and metabolites Signup and view all the answers

What is the osmolarity of plasma in mosmol/litre?

290 Signup and view all the answers

What is the pressure exerted by 1 osmole in 1 litre of solution?

17,000 mmHg Signup and view all the answers

What is the term for the osmolarity of a solution that has the same osmolarity as plasma?

Isotonic Signup and view all the answers

Why is it important to strongly control the osmolarity of plasma?

To prevent changes in plasma volume Signup and view all the answers

What type of ions are responsible for crystalloid osmotic pressure?

Small, diffusible ions Signup and view all the answers

Why is there no crystalloid osmotic pressure difference across capillary walls?

Because ions cross capillary walls easily Signup and view all the answers

What is the approximate oncotic pressure exerted by proteins in interstitial fluid?

25 mmHg Signup and view all the answers

Which of the following ions has a higher concentration in the intracellular space compared to the extracellular space?

K+ Signup and view all the answers

What is the primary function of the oncotic pressure in capillaries?

To facilitate fluid transport across capillaries Signup and view all the answers

What is the concentration of protein in interstitial fluid?

70 g/L Signup and view all the answers

Which of the following statements is true about the ionic composition of plasma and interstitial fluid?

The ionic composition of plasma and interstitial fluid is similar but not identical Signup and view all the answers

What is the major ion that controls blood volume?

Na+ Signup and view all the answers

What is the purpose of the crystalloid osmotic pressure in capillaries?

To balance the oncotic pressure Signup and view all the answers

Which of the following cellular processes is critical for the function of nerve and muscle cells?

All of the above Signup and view all the answers

What is the primary function of albumin in plasma?

Maintenance of plasma oncotic pressure Signup and view all the answers

What is the approximate concentration of fibrinogen in plasma?

3 g/litre Signup and view all the answers

Which of the following plasma proteins is involved in the immune system?

α, β, and γ globulins Signup and view all the answers

What is the approximate total quantity of proteins in plasma per litre?

70 g/litre Signup and view all the answers

What is the primary function of α, β, and γ globulins in plasma?

Haemostasis and immune system Signup and view all the answers

What is the osmolarity of plasma that influences fluid movement?

300 mmol/litre Signup and view all the answers

What is the classification of albumin based on its function?

None of the above Signup and view all the answers

What is the approximate concentration of α, β, and γ globulins in plasma?

0.7-13 g/litre each Signup and view all the answers

Study Notes

Body Fluids

The human body is composed of approximately 60% water, with a total body water (TBW) of around 42 liters in a 70kg young man.
Body fluids are distributed into three main compartments: plasma (5% of TBW), interstitial space (15% of TBW), and intracellular space (40% of TBW).
The major constituents of body fluids are ions (electrolytes), proteins, dissolved gases, nutrients, and metabolites.
Sodium, chloride, and potassium ions are the major ions in body fluids, and their concentrations differ significantly between extracellular fluid (ECF) and intracellular fluid (ICF).

Osmolarity and Osmotic Pressure

Osmolarity is the measure of the total number of freely diffusible entities in a solution, with a unit of osmoles per liter (osm/L).
Osmolality is the measure of osmoles per kilogram of solvent.
The osmolarity of plasma is approximately 290 mosm/L, which is strongly controlled to maintain a balance with the intracellular fluid.
The osmotic pressure of a solution is determined by the total number of freely diffusible entities, with a 1% difference in osmolarity between ECF and ICF resulting in a pressure of >50 mmHg across the cell membrane.

Crystalloid and Oncotic Osmotic Pressure

Crystalloid osmotic pressure is due to small diffusible ions, such as sodium, chloride, and potassium, which are evenly distributed across the capillary walls.
Oncotic osmotic pressure, also known as colloidal osmotic pressure, is due to proteins, such as albumin, which are not easily diffusible across the capillary walls and exert a pressure of approximately 25 mmHg.

Plasma Proteins

Plasma proteins have a total concentration of approximately 70 g/L, with albumin being the most abundant (48 g/L).
Albumin is responsible for exerting the plasma oncotic pressure, transporting ions, and buffering pH.
Other plasma proteins, such as α, β, and γ globulins, are involved in hemostasis, transport, and immune system functions.
Fibrinogen is a protein involved in hemostasis.

Ionic Composition of Body Fluids

The ionic composition of plasma and intracellular fluid differs significantly, with sodium and potassium being the major ions in each.
The relative concentrations of potassium, sodium, and calcium ions between intracellular and extracellular spaces are critical for cell function, particularly membrane potential, action potential, and nerve and muscle function.

Blood Cells

The main types of blood cells include red blood cells, white blood cells, and platelets.
The normal ranges for red blood cell count, white blood cell count, and hemoglobin are important to know.
Anemia is a condition characterized by a reduced number of red blood cells or a lack of hemoglobin in the blood.

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Description

Learn about the volumes and composition of body fluid compartments, measurement principles, and osmolarity equilibria across membranes. This quiz is based on a lecture by Professor Jeremy PT Ward.