Lecture 3

Question 1

Pressure formula?

Answer 1

P(N/m^2) = Force/Area

Question 2

Density formula?

Answer 2

D(kg/m^3) = Mass/Volume

Question 3

How does pressure vary with fluid depth?

Answer 3

• Pressure decreases as height increases
• Pressure increases as height decreases

P = pgh
Pressure = (density)(gravity)(height)
Pa = (Kg/m^3)(m/s^2)(m)

Question 4

What does pressure depend on?

Answer 4

• The height of the liquid
• The density of the fluid
• The acceleration due to gravity

Question 5

Clinical uses of hydrostatic pressure?

Answer 5

• Intravenous drips
• Lavage (cleaning out of body cavities)
• Removal of body fluids
• Drip feeding

Question 6

What is Pascal’s Principle?

Answer 6

Any pressure applied to the surface of an enclosed fluid is transmitted, undiminished to all points within the fluid

F2 = F1 (A2/A1)

Question 7

What is atmospheric pressure?

Answer 7

Caused by a blanket of air around the earth. The pressure results from the ‘weight’ of the air. The force exerted on a surface by the air above it, as gravity pulls it towards the earth

PA = H + pgh

Question 8

1atm = ?

Answer 8

1atm = 1.013x10^5 Pa

Question 9

What are factors that can increase bladder pressure?

Answer 9

• Stress
• Pregnancy
• Coughing
• Strain
• Sitting up

Question 10

Fluid pressure in the bladder?

Answer 10

As the volume of urine increases in the bladder, the fluid pressure increases, unit a threshold is met. Once the threshold is met, pressure detector cells on the walls of the bladder tell the brain that the bladder is full, and a contraction of the bladder is initiated (urination)

Question 11

How does Pascal’s Principle apply in the prevention of bedsores?

Answer 11

They’re caused by patients spending long periods of time in the same position. They occur in the parts of the body that have direct contact with the mattress (where pressure is applied). They can be prevented by continuously moving the patient through the use of an air or fluid filled mattress. Bc since the fluid/air moves, the mattress will fit around all of the bony (at risk regions) on your body (increases the contact surface area, which decreases the pressure associated with the body).

Question 12

How does Pascal’s Principle apply in the onset of glacuoma?

Answer 12

Glaucoma occurs when there is a buildup of excess fluid in the eye. This causes an increase in the intra-ocular pressure, damaging the optic nerve, resulting in blindness. It can be treated by using a laser to create channels so the excess fluid can escape, therefore reducing the intra-ocular pressure throughout the entire eye.