Review of posters 08/05/2016

Question 1

What is blood pressure?

Answer 1

The outwards hydrostatic pressure the blood exerts on the walls of the blood vessels.

Question 2

Systemic systolic arterial blood pressure

Answer 2

The hydrostatic pressure the blood exerts on the blood walls during the hearts contraction

Question 3

Systemic diastolic arterial blood pressure.

Answer 3

The hydrostatic pressure the blood exerts on the blood vessels when the heart is relaxed.

Question 4

How does a sphygmanometer work?

Answer 4

If an external pressure greater than systole is applied to an artery- it cuts the blood supply off to that area. This is not audible.
However if you apply a pressure between that of systole and diastole to the blood vessel, the flow through the vessel will be turbulent and this will be audible.
Therefore when the cuff is pumped above systole you can’t hear anything, yet when it reaches systole you begin to hear a noise, then at diastole the noise stops.

Question 5

What drives blood flow around the body?

Answer 5

The pressure gradient between the aorta and the right atrium.

Question 6

How can the pressure gradient be calculated?

Answer 6

Mean arterial pressure- central venous pressure (pressure in the right atrium)

Question 7

What is mean arterial pressure?

Answer 7

The average blood pressure throughout one cardiac cycle (includes diastole).

Question 8

What are the equations that allow you to calculate MAP?

Answer 8

((2xdiastole)+systole)/2

or

Diastole + 1/3 (systole-diastole)

Question 9

In terms of commonly used cardiac physiology outputs, how would you describe MAP?

Answer 9

MAP= CO x TPR
CO= cardiac output which equals the HR x SV
Total peripheral resistance is the sum of the resistance in all the systemic vessels

Question 10

What should your MAP be?

Answer 10

70-100

Below 60 would struggle to perfuse brain, kidney.

Question 11

What are baroreceptors responsible for?

Answer 11

Short term regulation of MAP. Do so in a negative feedback system.

Question 12

Where are baroreceptors in the body?

Answer 12

Aortic arch and carotid sinus.

Question 13

Process of standing up too quickly in a normal individual.

Answer 13

When the person gets up too quickly, it causes a drop in the venous return to the heart (due to gravity). This means there is a decrease in MAP. The baroreceptors stop firing as much now. The sympathetic tone to the heart increases and the vagal tone decreases. Also the sympathetic constrictor tone to venules and arterioles increases increasing venous return to the heart. This all drives MAP up.

Question 14

Are baroreceptors a good long term MAP control?

Answer 14

No this is because they re-set to the higher steady state. E.g. if the person has high blood pressure, the baroreceptors wouldn’t recognise this as being abnormal because they are used to that ‘steady state’. They will only fire again if there are acute changes from the new normal.

Question 15

What is internal respiration?

Answer 15

The intracellular mechanisms consuming O2 and producing CO2

Question 16

What is external respiration?

Answer 16

The process that lead to exchange of O2 and CO2 between the atmosphere and the cells.

Question 17

What are the four stages to external respiration?

Answer 17

Ventilation- process of getting atmospheric air in to the alveoli
Gas exchange between the alveoli and the blood
Transport in the blood
Gas exchange between the alveoli and the tissues.

Question 18

What is ventilation?

Answer 18

The mechanical process of moving air between the atmosphere and the alveoli.

Question 19

Boyle’s Law

Answer 19

Pressure exerted by a gas decreasing as the volume increases.

Question 20

How do changes in pressure draw air into the lungs?

Answer 20

Chest expands causing the lungs to expand. Volume is increasing in the thorax and therefore pressure is decreasing to below that of atmospheric pressure. Air then moves down its pressure gradient into the lungs.

Question 21

What causes the lungs to expand when they are not actually attached to the chest wall?

Answer 21

Negative intrapleural pressure
Intrapleural fluid cohesiveness- water molecules in the pleural fluid have a strong surface tension and therefore resist being pulled apart. This means the two pleural layers stick together- making the lungs expand.

Question 22

Inspiration

Answer 22

Active process
Involves diaphragm contracting and flattening
External intercostal muscles contracting and lifting the rib cage up and out.

Question 23

Expiration

Answer 23

Passive process

Inspiratory muscles contract and due to elastic recoil lungs and chest wall spring back into original shape.

Question 24

What causes the lungs to adopt their original shape during expiration?

Answer 24

The elastic connective tissue

Alveolar surface tension

Question 25

What is alveolar surface tension?

Answer 25

The water molecules on the liquid-air interface have a strong attraction to each other and therefore resist being pulled apart.

Question 26

What is surfactant and why do we need it?

Answer 26

Surfactant is a mixture of lipids and proteins that sit in between the water molecules in the alveoli. This reduces the surface tension slightly so that the lungs can still expand.

Question 27

Neonatal respiratory distress syndrome

Answer 27

Babies born with not enough surfactant- therefore they have extreme difficulty breathing.

Question 28

LaPlace’s law

Answer 28

The smaller the alveoli, the greater the tendency there is to collapse. Therefore smaller alveoli have more surfactant.

Question 29

What is alveolar interdependence?

Answer 29

If an alveoli is collapsing, the alveoli surrounding it will exert a stretch then recoil force. This causes the alveoli to open again.