Physiology

Question 1

What is shock?

Answer 1

Abnormality of the circulatory system resulting in inadequate tissue perfusion and oxygenation

Question 2

What is hypovolaemic shock?

Answer 2

decreased blood volume leads to decreased venous return, a decreased end diastolic volume and decreased in stroke volume. Decreased cardiac output and decreased blood pressure. Inadequate tissue perfusion

Question 3

What is Cardiogenic shock?

Answer 3

decreased cardiac contractility, decreased stroke volume, decreased CO and decreased BP leading to inadequate tissue perfusion

Question 4

tension pneumothorax-What is obstructive shock?

Answer 4

increased intrathoracic pressure leads to decreased venous return, decreased end diastolic volume, decreased stroke volume and therefore decreased CO and BP and inadequate tissue perfusion

Question 5

What is neurogenic shock?

Answer 5

Loss of sympathetic tone to blood vessels and heart, massive venous and arterial vasodilation, effect on HR.

• Decreased venous return and decreased SVR
• decreased HR
• DECREASED CO and BP
• inadequate tissue perfusion

Question 6

What is the management of shock?

Answer 6

1- ABCDE approach
2-high flow oxygen 
3-volume replacement except for cardiogenic shock
4-call for help early 
5-inotropes for cardiogenic shock 
6-immediate chest drain for tension pneumothorax
7-adrenaline for anaphylactic shock 
8-vasopressers for septic shock 
9-treat cause as appropriate

Question 7

What is vasoactive shock?

Answer 7

release of vasoactive mediators. massive venous and arterial vasodilation also increased capillary permeability.
decreased venous return and decreased SVR. Decreased cardiac output and decreased blood pressure. inadequate tissue perfusion

Question 8

What are the causes of hypovolaemic shock?

Answer 8

• haemorrhage eg trauma, surgery, GI, haemorrhage

- vomiting, diarrhoea, excessive sweating

Question 9

In shock til what blood volume to compensatory mechanisms work for?

Answer 9

until >30% of blood volume is lost

Question 10

Apob containing lipoproteins function?

Answer 10

I) To muscle for ATP biogenesis ii) adipocytes for storage

Question 11

What is Systemic systolic arterial blood pressure-

Answer 11

the pressure exerted by the blood on the walls of the aorta and systemic arteries when the heart contracts- should not normally reach or exceed 140mmhg under resting conditions

Question 12

What is Systemic diastolic arterial blood pressure?

Answer 12

the pressure exerted by the blood on the walls of the aorta and systemic arteries when heart relaxes and should not normally exceed 90mmhg

Question 13

What is pulse pressure?

Answer 13

The difference between systolic and diastolic blood pressures. Normally between 30-5mmhg

Question 14

Difference between cardiac output and stroke volume?

Answer 14

• the volume of blood pumped by each ventricle of the heart per minute
• the volume of blood pumped by each ventricle of the heart per heart beat

Question 15

Define hypertension?

Answer 15

Clinical blood pressure of 140/90mmhg or higher and day time average of 135/85 mmhg or higher

Question 16

What are the steps in a baroreceptor reflex in the prevention of postural hypotension?

Answer 16

1- When a normal person suddenly stands up from sitting down gravity leads to a low venous return to the heart
-decreased vagal tone and MAP
-reduced rate of firing of baroreceptors
2- this leads to firing of sympathetic tone increasing cardiac output and heart rate
3-sympathetic constrictor tone increases leading to increase systemic vascular resistant-arterioles are the main site for SVR.

Sympathetic constrictor tone to veins increases the venour return to the heart and stroke volume

All of this leads to rapid correction of the transient fall in MAP: HR increases, SV increases, SVR increase

Question 17

What are the three hormones that regulate extracellular fluid volume?

Answer 17

• renin-angiotensin-aldosterone system
• natriuretic peptides
• antidiuretic hormone (arginine vasopressin ADH)

Question 18

RAAS system is activated when low plasma volume and blood pressure is detected. true/false?

Answer 18

True

Question 19

What 3 things regulates the RAAS system causing the release of renin from the juxtaglomerular kidney?

Answer 19

• renal artery hypotension caused by systemic hypotension and drop in BP
• stimulation of renal sympathetic nerves
• decreased sodium renal tubular fluid sensed by macular densa