lecture 1 - control of blood pressure & shock

Question 1

What is the definition of shock?

Answer 1

Inadequate perfusion of tissues with blood leading to generalised tissue hypoxia which may cause irreversible damage.

Question 2

What is the equation for MABP (mean arterial blood pressure)?

Answer 2

Cardiac Output * Total peripheral resistance

Question 3

What is the equation for CO (cardiac output)?

Answer 3

Heart rate * Stroke volume

Question 4

What causes shock?

Answer 4

A significant drop in mean arterial blood pressure

Question 5

What receptors in the body monitor mean arterial blood pressure?

Answer 5

Baroreceptors

Question 6

What 3 factors can be adjusted to maintain MABP?

Answer 6

heart rate, stroke volume, total peripheral resistance

Question 7

What type of receptor are baroreceptors?

Answer 7

Mechanoreceptors - stimulated by stretch

Question 8

Where are the baroreceptors that measure MABP found?

Answer 8

Carotid sinus & Aortic arch

Question 9

What are the 3 key classifications of shock?

Answer 9

Hypovolaemic, distributive, cardiogenic

Question 10

What is hypovolaemic shock?

Answer 10

Drop in BP due to decreased blood volume, which ultimately drops the preload of the heart and therefore decreased MABP.

Question 11

What are the causes of hypovolaemic shock?

Answer 11

Vomiting/diarrhoea, internal bleeding, haemorrhage, burns, diuresis

Question 12

What is distributive shock?

Answer 12

Generalised vasodilation, that decreases the afterload of the heart and TPR and drops MABP

Question 13

What are the causes of distributive shock?

Answer 13

Anaphylaxis, sepsis, neurogenic

Question 14

What is cardiogenic shock?

Answer 14

Drop in MABP due to reduced cardiac output

Question 15

What are the causes of cardiogenic shock?

Answer 15

Pump failure (MI, arrhythmia, heart failure, etc), extra-cardiac obstruction

Question 16

What is the immediate response to haemorrhage to maintain blood pressure?

Answer 16

Baroreceptor reflex triggers increase in heart rate, increased stroke volume and vasoconstriction

Question 17

What is the intermediate response to haemorrhage to maintain blood pressure?

Answer 17

Fluid shift from tissues to capillaries to increase plasma volume

Question 18

What is the long term response to haemorrhage to maintain blood pressure?

Answer 18

Replacement of fluid in the body and red blood cell regeneration

Question 19

What are the 3 processes triggered by the baroreceptor reflex?

Answer 19

Increased stroke volume, increased heart rate, increased total peripheral resistance

Question 20

What are the 3 ways water/plasma volume is restored after blood loss?

Answer 20

ADH release to retain water, RAAS activation to reduce urine output/retain Na/H2O, thirst triggered