arterial blood pressure

Question 1

What reflex controls short term mean arterial blood pressure?

Answer 1

The baroreceptor relfex

Question 2

What is blood pressure?

Answer 2

It is the outwards, hydrostatic pressure exerted by the blood on the blood vessel walls.

Question 3

What blood pressure do we measure in clinical practise?

Answer 3

Systemic arterial blood pressure

Question 4

What is laminar flow and can it be heard?

Answer 4

Non-turbulent flow that travels in layers. It is not audible through a stethoscope.

Question 5

What is the term used to describe how blood flows through arteries in normal fashion?

Answer 5

Laminar flow

Question 6

What would be heard if external pressure was applied to an artery exceeding the systolic blood pressure and why?

Answer 6

No sound would be heard as the blood supply would be blocked

Question 7

Why do you hear a sound when decreasing the pressure of a blood pressure cuff?

Answer 7

When the cuff pressure is between systolic and diastolic blood pressure the blood flow becomes turbulent when the blood pressure exceeds the cuff pressure. This turbulent flow can be heard through a stethoscope.

Question 8

What is the first sound when taking a blood pressure?

Answer 8

The heart at peak systolic pressure (the highest pressure to overcome the external pressure from the cuff).

Question 9

At what point is diastolic pressure recorded?

Answer 9

The fifth Korotkoff sound - the point at which sound disappears.

Question 10

In relation to blood pressure, what drives the blood around the systemic circulation?

Answer 10

There is a pressure gradient between the aorta and the right atrium.

Question 11

What is the formula for the pressure gradient?

Answer 11

Pressure gradient = mean arterial pressure (MAP) - central venous (right atrial) pressure (CVP)

Question 12

What is mean arterial blood pressure?

Answer 12

The average arterial blood pressure during a single cardiac cycle, which involves contraction and relaxation of the heart.

Question 13

What 2 formula can be used to estimate mean arterial blood pressure?

Answer 13

MAP = ((2x diastolic pressure) + systolic pressure) / 3
OR
MAP = diastolic blood pressure + 1/3 pulse

Question 14

What is normal arterial blood pressure?

Answer 14

<90 diastolic

Question 15

What is the normal range of mean arterial blood pressure?

Answer 15

70 - 105 mmHg

Question 16

What MAP is needed to perfuse the coronary arteries, brain and kidneys?

Answer 16

At least 60 mmHg

Question 17

Mean arterial blood pressure must be regulated within a narrow range to ensure…

Answer 17

Pressure is high enough to perfuse internal organs but not too high that it will cause damage to the blood vessels or place extra strain on the heart.

Question 18

What is the relationship between MAP, CO and total peripheral resistance (TPR)

Answer 18

MAP = CO x TPR

Question 19

What is TPR?

Answer 19

Total peripheral resistance is the sum of resistance of all peripheral vasculature in the systemic circulation.

Question 20

What type of vessel has the most resistance?

Answer 20

Arterioles

Question 21

Does the sympathetic or parasympathetic system have greater influence of MAP and why?

Answer 21

The sympathetic system as it affects heart rate, the arterioles and veins whereas the parasympathetic system can only affect heart rate.

Question 22

What type of response is the baroreceptor reflex?

Answer 22

Negative feedback

Question 23

How do baroreceptors detect the blood pressure?

Answer 23

They are stretch receptors - the higher the blood pressure the higher the stretch and the more firing of signals.

Question 24

What causes postural hypotension?

Answer 24

Failure of the Baroreceptor responses to gravitational shifts in blood, when moving from horizontal to vertical position.

Question 25

How is blood pressure regulated in the long term?

Answer 25

Controlled by controlling the extracellular fluid volume

Question 26

External fluid is divided into 2 compartments. What are the names of the two volumes?

Answer 26

``` Plasma volume (PV) and interstitial fluid volume (IFV) ECFV = PV + IFV ```

Question 27

If plasma volume falls what happens to the interstitial fluid volume?

Answer 27

Compensatory mechanisms shift the interstitial fluid from the interstitial compartment to the plasma compartment.

Question 28

What are the two main factors that affect extracellular fluid volume?

Answer 28

Water excess or deficit. | Na+ excess or deficit.

Question 29

How is extracelluilar fluid volume regulated?

Answer 29

Hormones act as effectors, regulating the water and salt balance in our bodies

Question 30

Give hormones that regulate extracellular fluid volume

Answer 30

``` The Rennin-Angiotensin-Aldosterone system (RAAS) Atrial Natiuretic Peptide (ANP) Antidiuretic Hormone (ADH) ```

Question 31

What are the three components of RAAS?

Answer 31

Rennin Angiotensin Aldosterone

Question 32

What are the affects of angiotension II?

Answer 32

1. Causes systemic vasocontriction 2. Stimulated increased ADH release 3. Makes the person feel more thirsty 4. Stimulates the release of aldosterone

Question 33

What is the rate limiting step for RAAS?

Answer 33

Rennin secretion

Question 34

What triggers the release of peptide hormones in the Atrial Natiuretic Peptide system?

Answer 34

Atrial distension | hypervolaemic states

Question 35

What is the effect of the peptide hormones?

Answer 35

They cause excretion of salt and water in the kidneys = reducing blood volume and blood pressure. Vasodilator - decreases blood pressure Decreases Rennin release

Question 36

What is antidiuretic hormone?

Answer 36

Peptide hormone derived from a prehormone precursor synthesised by the hypothalamus and stored in the posterior pituitary

Question 37

Where does the ANP system get its name?

Answer 37

The peptides are synthesised and stored by atrial myocytes

Question 38

What two changes stimulate the secretion of ADH?

Answer 38

Reduced extracellular fluid volume | Increased extracellular fluid osmolarity

Question 39

What is the effect of ADH?

Answer 39

Acts in the kidney tubules to increase the reabsoption of water (conserve water, urine becomes more concentrated) Causes vasoconstriction of blood vessels