Physiology of Body Fluids

Question 1

What does hypertensive mean?

Answer 1

• Disruption of a normal negative feedback loop, leading to an abnormally high blood pressure

Question 2

Give examples of bodily fluids

Answer 2

• Saliva
• Plasma
• Cerebral spinal fluid
• Tissue fluid
• Amniotic fluid
• Urine
• Seminal/vaginal fluid
• Sweat/tears

Question 3

What are the components of body fluids?

Answer 3

• Fluid (solvent) in the body is water

- Dissolved substances (solutes) in the water like electrolytes and proteins

Question 4

What is the distribution of body fluids?

Answer 4

• Total volume of water in body = 42 litres
• Intracellular fluid = 26 litres
• Extracellular fluid = 16 litres
• –> Plasma volume= 3 fluids

Question 5

What is the role of electrolytes?

Answer 5

• Crucial for cell signalling
• Action potentials
• Acid base balance
• Muscle contraction
• Osmosis

Question 6

Give examples of electrolytes

Answer 6

• Sodium, calcium, potassium ions
• Protons
• Carbon dioxide and oxygen
• Proteins

Question 7

Give examples of non-electrolytes

Answer 7

• Glucose
• Phospholipids
• Cholesterol
• Urea

Question 8

What is the role of body fluids

Answer 8

• Major site for biological reactions
• Transport
• Lubrication
• Temp regulation
• Cushioning

Question 9

What might cause variations in water content?

Answer 9

• Dehydration
• Metabolism
• Hyponatraemia- low sodium
• Oedema (excess tissue fluid in interstitial)

Question 10

What are signs of dehydration?

Answer 10

• Dizziness
• Thirst
• Sunken eyeballs
• Decreased cap refill
• Postural bp drop
• Loss of skin turgor

Question 11

Who might be more vulnerable to dehydration?

Answer 11

Young and elderly more vulnerable to dehydration

Question 12

What is diffusion?

Answer 12

• Passive movement of molecules down a concentration gradient

Question 13

What is diffusion affected by?

Answer 13

• Temperature, membrane permeability, concentration, solubility, size, SA:Vol and diffusion pathway

Question 14

What is osmosis?

Answer 14

• Movement of water through a selectively permeable membrane from an area of low osmolarity to an area of high osmolarity

Question 15

What is osmolarity?

Answer 15

The number of particles in solution

Question 16

What is molarity?

Answer 16

The number of molecules in solution

Question 17

What is the difference between osmolarity and osmolality?

Answer 17

• Osmolarity is osmotically active molecules per litre of water (vol)
• OsmolaLity is osmotically active molecules per kilo of water (mass), a fraction more dilute than their molar equivalent
• Both measures of osmotic strength

Question 18

What is osmotic pressure?

Answer 18

• Pressure required to prevent osmosis

- High pressure = high osmolarity

Question 19

What does hydrostatic pressure involve?

Answer 19

• Gravity and fluid

Question 20

What is oncotic osmotic pressure?

Answer 20

Involves pressure exerted by proteins

Question 21

What is Starling’s hypothesis?

Answer 21

Fluid flow out of the capillary depends on

• Oncotic pressure in capillary and interstitial fluid
• Hydrostatic pressure in the capillary

Question 22

What is the effective osmolality?

Answer 22

• Concentration of particles which have the capacity to exert an osmotic force

Question 23

What is tonicity?

Answer 23

• Refers to effect of solutions on cell volume

- Concentrations of solution relative to the cell

Question 24

What are the types of tonicity?

Answer 24

• Isotonic solution
• Hypertonic solution
• Hypotonic solution

Question 25

What is an isotonic solution?

Answer 25

• Concentration of solutes is equal to inside cell

- No net movement

Question 26

What is a hypertonic solution?

Answer 26

• Concentration of solutes greater than inside cell

- Solvent will flow out of the cell

Question 27

What is a hypotonic solution?

Answer 27

• Concentration of solutes less than inside cell

- Solvent will flow into the cell