LECTURE 2 - 1ST SEM

Question 1

What are fluids?

Answer 1

Things which flow (including liquids and gas)

Question 2

What is a solid-state?

Answer 2

Characterized by internal order and fixed atomic position. Helping it keep the shape.

Question 3

What is a liquid state?

Answer 3

When atoms or molecules have strong very cohesive forces that hold them together

Question 4

How do molecules behave in liquids?

Answer 4

• Free to move relative to one another
• Readily take shape of container
• Flow readily, using considerable force to seperate molecules

Question 5

Why are liquids considered incompressible?

Answer 5

As cannot occupy smaller volume without the exertion of enormous pressures

Question 6

What is the formula for pressure?

Answer 6

P = F/A

Question 7

How is pressure created in gas?

Answer 7

No attractive forces between molecules and only forces is exerted via collisions.

Question 8

How can the penetrating ability of an object be determined?

Answer 8

Depends largely upon the pressure rather than just the force

Question 9

Why do hypodermic needles have large penetrating pressure?

Answer 9

• They have an extremely small tip area where small force can result in large penetrating pressure
• Sharper needles require less force to produce high penetrating pressure.

Question 10

What is the formula for pressure in liquids? What does the formula indicate?

Answer 10

P=p (fluid density) x g (acceleration due to gravity) x h (fluid depth)

Pressure caused by liquid is proportional to the depth of liquid and density.

Absolute pressure is the sum of atmospheric pressure and liquid pressure.

Question 11

What factors determine the pressure in a container in a liquid?

Answer 11

Depth of liquid and not shape

Question 12

What is the theory behind pressure distributed in static liquid?

Answer 12

• Pressure is exerted equally in all directions in static liquid
• At any given depth, it is found that equilibrium that forces are exerted upon it in all directions
• Forces must be exerted in pairs such that the net force is zero

Question 13

How does pressure behave in a given vessel?

Answer 13

• Pressure increases with depth.
• Horizontal pressure on the walls also increase.

Question 14

How does pressure work in I.V Apparatus?

Answer 14

• Pressure is determined by height of the liquid surface above the point of input in patient
• Pressure is transmitted through the tubing, even if coils are present
• Pressure at the patient under static (no flow) conditions would be the same regardless of the configuration of the tubing
  (refer to the diagram)

Question 15

What is pascals principle in the transmission of pressure?

Answer 15

Any changes of pressure in an enclosed fluid are transmitted undiminished to all parts of the fluid

Question 16

How can Pascal’s principle be applied clinically?

Answer 16

• Prevention of pressure sores
• Through cerebrospinal fluid in the spinal cord
• Protection of unborn fetus through the protection of external forces
• Through enclosed fluid in the eye
• To explain the effects of collected fluid in the pericardial and pleural cavities

Question 17

How can pascals principle help in the prevention of pressure sores?

Answer 17

• Through the use of air or water matters helps prevent the formation of decubitus ulcers
• Through using air/water mattresses allows for a closed fluid system, allowing pressure to be evenly distributed.
• When the patient lies on the mattress, the same pressure is exerted against every part of the body which is in contact with the mattress.

Question 18

How does pressure (pascals laws) cause pressure sores?

Answer 18

Decubitus ulcers (bed sores) can be caused by ordinary pressure sores due to large pressure being exerted on parts at risk

Question 19

What is buoyancy?

Answer 19

• Is the lifting force requ

Question 20

What is Archimedes’ principle?

Answer 20

• Is when a buoyant force arises from a difference in liquid pressure above and below the object.
• The buoyant force on the submerged object becomes equal to the weight of the liquid that is displaced.

Question 21

What is buoyancy?

How does buoyancy affect the weight of an object?

Answer 21

the ability or tendency of something to float in water or other fluid.

• Buoyancy causes an object to weigh less than it does in the air

Question 22

What does a hydrometer measure?

Answer 22

• Measures the specific gravity of a liquid, by floating a glass tube in a liquid.
• If gravity of liquid is increased, it causes the hydrometer to float higher.

Question 23

What can a hydrometer be used to measure clinically?

Answer 23

It can be a urinometer - to measure the gravity of urine, an important physiological indicator as some diseases alter the composition of urine that change the gravity

Question 24

Why do objects weigh less in water than in air?

Answer 24

• When weighed in water, buoyant forces equal to the weight of water that is displaced.
• Causing the difference in weight between air and water

Question 25

What is laminar flow?

Answer 25

- This is when the average flow speed is about half the maximum speed found at the center. - It represents the minimum energy loss

Question 26

What causes turbulent flow?

Answer 26

- Is when the flow is speeded up past a certain critical speed or there is an obstruction in the flow path - Causing eddies to form and laminar flow to break down

Question 27

How does pressure behave in non- or flowing fluids?

Answer 27

Pressure hit at all points in horizontal tubes when there is no flow Uniform pressure drops when there is smooth flow

Question 28

What is the formula for volume flow rate?

Answer 28

Volume flow rate = Volume/Time

Question 29

What is the formula to represent the relationship of the smooth flow of an ideal fluid?

Answer 29

F = P1 - P2 ------------------- R R = Effective resistance to flow F = Volume flow rate P1 & P2 = Pressures at the upstream and downstream ends of the tube

Question 30

How does fluid flow through a tube?

Answer 30

- Fluid flows in a smooth layer. - The layer nearest the wall will be at rest. - Speed gradually increases to a maximum on the central axis of the vessel

Question 31

Why is important to maintain laminar flow clinically?

Answer 31

- It allows for efficient fluid circulation - in things like intravenous fluid apparatus or circulatory system of the body

Question 32

How can turbulent flow be prevented clinically?

Answer 32

- By making smooth transitions to different tube sizing.

Question 33

What is the formula for Poiseuile law?

Answer 33

Q = πr^4P ------------------ 8ηL Q = flow rate η = Fluid viscosity L = Pipe Length P = Pressure difference between the ends

Question 34

What is Poiseuille's Law?

Answer 34

The laminar flow rate of an incompressible fluid along a pipe is proportional to the fourth power of the pipe's raduis.

Question 35

What is the relationship between blood viscosity and fluid pressure?

Answer 35

- Viscosity of blood is found to decrease with increasing fluid pressure - Implies that the flow rate would be more than doubled by doubling the pressure gradient.