BP

Question 1

What is the formula for mean blood pressure?

Answer 1

Mean BP = SBP + 2x DBP/3

Question 2

What is the normal human blood pressure?

Answer 2

The normal human blood pressure is 120/80 mmHg.

Question 3

What are the determinants of blood pressure?

Answer 3

The determinants of blood pressure are cardiac output and vascular resistance.

Question 4

What is the formula for blood pressure according to Ohm’s law?

Answer 4

BP = CO x SVR

Question 5

How does gravity affect blood pressure?

Answer 5

Blood pressure is higher in the feet and lower in the head due to gravity.

Question 6

How does arterial compliance affect blood pressure?

Answer 6

Arterial compliance refers to the ability of arteries to stretch and store elastic potential energy in systole and release it to maintain flow in diastole. Stiff arteries, such as those in old age, reduce compliance and increase systolic blood pressure.

Question 7

How does blood viscosity affect blood pressure?

Answer 7

Blood viscosity contributes to resistance to flow. Higher viscosity, such as in high protein/hypercellular blood, requires higher pressure to maintain flow.

Question 8

What is cardiac output and how is it calculated?

Answer 8

Cardiac output is the amount of blood pumped by the heart in one minute. It is calculated by multiplying stroke volume (the amount of blood pumped out with each heartbeat) by heart rate (the number of heartbeats per minute).

Question 9

What is stroke volume?

Answer 9

Stroke volume is the amount of blood pumped out of the heart with each contraction.

Question 10

What factors affect stroke volume?

Answer 10

Preload, contractility, and afterload are the main factors that affect stroke volume.

Question 11

What are the main components of plasma?

Answer 11

The main components of plasma are water, salts, and proteins.

Question 12

What controls blood volume?

Answer 12

The kidney controls blood volume by regulating the retention or excretion of salt and water. Hormones such as aldosterone and ADH (antidiuretic hormone) play important roles in this regulation.

Question 13

What is intrinsic heart rate?

Answer 13

Intrinsic heart rate is the heart rate set by the sinoatrial (SA) node, the natural pacemaker of the heart.

Question 14

What is the role of the autonomic nervous system in heart rate control?

Answer 14

The autonomic nervous system plays a major role in heart rate control. The sympathetic nervous system increases heart rate through beta-1 adrenergic receptors, while the parasympathetic nervous system (vagus nerve) slows heart rate through M2 muscarinic receptors.

Question 15

What is the role of adrenaline in heart rate control?

Answer 15

Adrenaline (epinephrine) increases heart rate through beta-1 adrenergic receptors.

Question 16

What is Starling’s Law?

Answer 16

Starling’s Law states that the force of contraction of the heart is a function of the length of the muscle fibers. The longer the muscle fibers are stretched, the stronger the subsequent contraction will be.

Question 17

How is fiber length determined in Starling’s Law?

Answer 17

Fiber length is determined by end-diastolic volume, which is in turn determined by venous return.

Question 18

What is preload?

Answer 18

Preload is the amount of blood returning to the heart, which determines the end-diastolic volume and thus the stretch of the cardiac muscle fibers.

Question 19

What are some factors that affect preload?

Answer 19

Circulating blood volume, venous tone, autonomic nervous system, circulating vasoconstrictors, and local vasoactive substances can all affect preload.

Question 20

What is afterload?

Answer 20

Afterload is the resistance that the heart must overcome to eject blood during systole. This resistance is determined by the tone and compliance of the arteries.

Question 21

What is the relationship between cardiac output, peripheral resistance, and blood pressure?

Answer 21

Blood pressure is determined by the product of cardiac output and peripheral resistance. An increase in either cardiac output or peripheral resistance will increase blood pressure, while a decrease in either will decrease blood pressure.

Question 22

What is the role of local controls in blood pressure control?

Answer 22

Tissue perfusion is autoregulated in response to local need. Local controls occur at the level of the arteriole, with dilation being caused by low O2/high CO2 levels, acidosis, nitric oxide, and prostacyclin, and constriction being caused by endothelin.

Question 23

What are the circulating catecholamines involved in blood pressure control?

Answer 23

Adrenaline and noradrenaline are responsible for generalised and sustained responses to acute changes. Receptors include alpha (systemic arterioles - vasoconstriction (a1); heart - increase rate and force of contraction (b1)) and beta (systemic arterioles - vasodilation (muscle - b2)).

Question 24

What are the sensors involved in blood pressure control?

Answer 24

Baroreceptors located in the aortic arch and carotid body (at the carotid bifurcation) signal the brain via the vagus nerve and glossopharyneal nerve.

Question 25

Where are the control centres located for blood pressure control?

Answer 25

Control centres are located in the brainstem and include the cardio-accelerator centre, cardio-inhibitory centre, and vasomotor centre. They integrate sympathetic and parasympathetic responses.

Question 26

What are the effectors involved in blood pressure control?

Answer 26

Sympathetic nerves release noradrenaline (adrenergic), causing vasoconstriction (muscle vasodilation) and increased heart rate and force. Parasympathetic nerves release acetylcholine (cholinergic), causing vasodilation. The vagus nerve decreases heart rate.

Question 27

What are the causes of high blood pressure?

Answer 27

• Chronic kidney (renal) disease
• Structural causes
  
  • Renal artery stenosis (narrowing of the kidney arteries)
  • Aortic coarctation (narrowing of the aorta above the kidneys)
• Endocrine (hormonal) causes
  
  • High aldosterone levels (Conn’s syndrome)
  • High catecholamine levels (phaeochromocytoma)
  • High cortisol levels (Cushing’s syndrome)
  • High growth hormone levels (acromegaly)
• Pregnancy / pre-eclampsia
• Essential hypertension - multifactorial
  
  • (Poly) genetic
  • Obesity
  • High salt intake
  • High alcohol intake
  • Ethnicity

Question 28

What are the effects of chronic hypertension

Answer 28

Heart muscle damage (heart failure)
Large vessel damage
Aortic aneurysm (and rupture)
Cerebrovascular disease (stroke)
Coronary artery disease (angina, myocardial infarction)
Peripheral vascular disease (claudication, amputations)
Microvascular damage
Kidney dysfunction (CKD)
Brain dysfunction (multi-infarct dementia)
Exacerbates vascular effects of diabetes (kidneys, eyes and peripheral nerves)

Question 29

what are the Causes of shock

Answer 29

Cardiogenic (e.g. large MI) – low CO
Sepsis (e.g. meningitis) – low SVR
Anaphylaxis (e.g. penicillin or nut allergies) – low SVR
Low blood volume (e.g. bleeding, burns, diarrhea) – low CO
Sympathetic activation
Poor tissue perfusion
Organ malfunction (especially kidneys)
Acidosis (lactate)

Question 30

what are the Acute effects of severe hypertension

Answer 30

Aortic dissection
Acute heart failure (high afterload)
Confusion (‘encephalopathy’)
Cerebral hemorrhage
Retinal hemorrhage

Question 31

What is vaso-vagal episode?

Answer 31

A vaso-vagal episode, also known as neurally-mediated syncope, typically occurs as a reaction to a stressful episode. A disproportionate parasympathetic activation causes arteriolar dilation, slowing of heart rate, and a fall in blood pressure. Reduced cerebral perfusion can lead to a transient loss of consciousness.

Question 32

What is shock?

Answer 32

Shock is a state of organ hypoperfusion with resultant cellular dysfunction and death. The fundamental defect in shock is reduced perfusion of vital tissues. Symptoms include altered mental status, tachycardia, hypotension, and oliguria.