Arterial blood pressure

What is arterial blood pressure?

The outwards (hydrostatic) pressure exerted by the blood on blood vessel walls.

What is systolic arterial blood pressure?

The pressure exerted by the blood on the walls of the aorta and systemic arteries when the heart contracts.

What is the normal level of systolic arterial blood pressure?

Should not normally reach or exceed 140 mmHg under resting conditions

What is diastolic arterial blood pressure?

The pressure exerted by the blood on the walls of the aorta and systemic arteries when the heart relaxes- during diastole. Signup and view all the answers

What is the normal level of diastolic arterial blood pressure?

Should not normally reach or exceed 90 mm Hg under resting conditions Signup and view all the answers

What is hypertension?

Clinical presentation of blood pressure of 140/90 mmHg or higher and daytime average of 135/85 mmHg or higher. Signup and view all the answers

What is pulse pressure?

The difference between systolic and diastolic blood pressures Signup and view all the answers

What is the normal level of pulse pressure?

Normally between 30 and 50 mm Hg Signup and view all the answers

What happens when the cuff pressure of the stethoscope exceeds the systolic pressure?

Flow in the artery is blocked and no sound can be heard through the stethoscope. Signup and view all the answers

What happens when the cuff pressure of the stethoscope is between systolic pressure and diastolic pressure?

Flow is turbulent when blood pressure (blood pressure exceeds cuff pressure)- audible through the stethoscope. Signup and view all the answers

What happens when the cuff pressure of the stethoscope is below the diastolic pressure?

No sound is heard because of uninterrupted laminar flow Signup and view all the answers

What are the Korotkoff sounds?

There are 5 phases of the Korotkoff sounds which correspond to different phases of the cycle:- <ol> <li> <ol> <li>First sound heard – peak systolic pressure</li> </ol> </li> <li>Intermittent sounds due to turbulent flow exceeding cuff pressure- becomes more intense and swishing</li> <li>Becomes more crisp and distinct.</li> <li>Last sound heard at minimum diastolic pressure (muted/muffled).</li> <li>No sound heard- this corresponds to the diastolic blood pressure, the pressure in the arteries when the heart is at rest between beats.</li> </ol> Signup and view all the answers

What drives the blood flow for systemic circulation?

The ventricular contraction and thus, the pressure gradient between the aorta and the right atrium drives the blood during the systemic circulation. Signup and view all the answers

What is the formula for the pressure gradient for the systemic circulation?

Pressure gradient= Mean arterial pressure (MAP)- Central venous (right atrial) pressure (CVP) Signup and view all the answers

What is mean arterial blood pressure?

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

What is the normal range for the mean arterial blood pressure?

Normal range is about 70 - 105 mmHg Signup and view all the answers

What happens when the mean arterial blood pressure is too low?

Inadequate perfusion of tissues (must be 60+ mmHg) Signup and view all the answers

What happens when the mean arterial blood pressure is too high?

Can damage blood vessels and create extra strain Signup and view all the answers

What is the formula to calculate mean arterial blood pressure?

<ol> <li>MAP = [(2x diastolic pressure) + systolic pressure]/3</li> <li>DBP + 1/3 pulse pressure</li> </ol> Signup and view all the answers

What is cardiac output?

The volume of blood pumped by each ventricle per minute Signup and view all the answers

What is stroke volume?

The volume of blood pumped by each ventricle per heartbeat Signup and view all the answers

What is systemic vascular resistance?

The sum of resistance of all vasculature in the systemic circulation. The arterioles are the main vessels providing resistance. Signup and view all the answers

What are three important relationships to calculate Mean Arterial Pressure (MAP)?

<ol> <li>MAP = [(2x diastolic pressure) + systolic pressure]/3</li> <li>MAP = DBP + 1/3 pulse pressure</li> <li>MAP = CO x SVR = HR x SV x SVR</li> </ol> Signup and view all the answers

What is the baroreceptor reflex in regulating blood pressure?

The baroreceptor reflex is a negative feedback mechanism to regulate blood pressure. It consists of three components:- <ol> <li>Pressure sensor- baroreceptors</li> <li>Control centre- medulla</li> <li>Effectors- Heart (HR, SV) and blood vessels (SVR).</li> </ol> Signup and view all the answers

Where are the baroreceptors located?

Arch of aorta and the carotid sinus Signup and view all the answers

Why can't baroreceptors regulate blood pressure in the long term?

Baroreceptors cannot regulate blood pressure long-term because firing decreases if high blood pressure is sustained. Signup and view all the answers

What is the baroreceptor response to increased blood pressure?

<ol> <li>Increased arterial pressure stretches the wall of the blood vessel, triggering the baroreceptors.</li> <li>These baroreceptors then feedback to the autonomic nervous system. 3)The ANS then acts to reduce the heart rate and cardiac contractility via the efferent parasympathetic fibres (vagus nerve), and decrease sympathetic constrictor tone (decreasing SVR), thus reducing blood pressure.</li> </ol> Signup and view all the answers

What is the baroreceptor response to a decreased blood pressure?

<ol> <li>Decreased arterial pressure is detected by baroreceptors, which then trigger a sympathetic response.</li> <li>This stimulates an increase in heart rate and cardiac contractility, and increased sympathetic constrictor tone (increasing SVR), leading to an increased blood pressure.</li> </ol> Signup and view all the answers

How is postural hypotension corrected by the baroreceptor function?

The postural hypotension results from a failure of the baroreceptor responses to gravitational shifts in blood, when moving from horizonal to vertical position. <ol> <li>Decreased baroreceptor firing then triggers a sympathetic response</li> <li>This stimulates an increase in heart rate and cardiac contractility, and increased sympathetic constrictor tone (increasing SVR), leading to an increased blood pressure.</li> </ol> Signup and view all the answers

How do we diagnose if someone presents with postural hypotension?

A positive result is indicated by a drop, within 3 minutes of standing from lying position: <ol> <li>In systolic blood pressure of at least 20 mmHg (with or without symptoms).</li> <li>A drop in diastolic blood pressure of at least 10 mm Hg (with symptoms).</li> </ol> Signup and view all the answers