Cardiology Lectures 4-6: Blood Pressure

Question 1

What is blood pressure?

Answer 1

Blood Pressure is “the outwards (hydrostatic) pressure exerted by the blood on blood vessel walls”

Question 2

What is the upper limit of systolic blood pressure?

Answer 2

140

Question 3

What is the upper limit for diastolic BP?

Answer 3

90

Question 4

What is the term for normal blood flow?

Answer 4

Laminar

Question 5

What is the first Korotkoff sound?

Answer 5

Systolic BP

Question 6

What is the fifth Korotkoff sound?

Answer 6

Diastolic Pressure is Recorded at the Fifth Korotkoff Sound (point at which sound disappears

Question 7

What is the main driving force of the venous return to the heart?

Answer 7

MAP

Question 8

What is MAP?

Answer 8

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

Question 9

How do you calculate MAP?

Answer 9

(Diastolic x 2 + Systolic) divided by 3

Question 10

What is the other way to calculate MAP?

Answer 10

BDP + 1/3 Pulse pressure

Question 11

What is the normal range for MAP?

Answer 11

70-105

Question 12

What is the lowest MAP that allows perfusion of coronary arteries, brain and kidney?

Answer 12

at least 60

Question 13

What determines MAP?

Answer 13

CO and total peripheral resistance

Question 14

What is total peripheral resistance?

Answer 14

Sum of resistance of all peripheral vasculature in the systemic circulation

Question 15

What are the major resistance vessels?

Answer 15

Arterioles

Question 16

Where are you baroreceptors?

Answer 16

Aortic arch

Carotid sinus

Question 17

Which nerve signals to the medulla from the carotid sinus?

Answer 17

CN IX

Question 18

Which nerve signals to the medulla from the aortic baroreceptors?

Answer 18

CN X

Question 19

Why are baroreceptors important?

Answer 19

Short term BP regulations ie postural changes

Question 20

What is postural hypotension?

Answer 20

Results from failure of Baroreceptor responses to gravitational shifts in blood, when moving from horizontal to vertical position

Question 21

How is MAP controlled long term?

Answer 21

By hormones which control blood volume.

Question 22

What two main factors control extracellular fluid volume?

Answer 22

Water

Sodium

Question 23

What three mechanisms control long term blood pressure?

Answer 23

Rennin-Angiotensin-Aldosterone- System
Atrial Natriuretic Peptide
Antidiuretic hormone

Question 24

Where is rennin released?

Answer 24

Kidneys

Question 25

What does rennin do?

Answer 25

Stimulates the formation of angiotensin I

Question 26

What converts angiotensin I to angiotensin II?

Answer 26

ACE

Question 27

What does angiotensin II do?

Answer 27

1. Stimulates the release of aldosterone form the adrenal cortex 2. Vasocontriction 3. Stimulates thirst and the release of ADH

Question 28

What does aldosterone do?

Answer 28

Increased sodium and water retention therefore increasing plasma volume

Question 29

What cells release rennin?

Answer 29

Granular cells

Question 30

What makes up the juxtaglomerular region?

Answer 30

Macula densa Extraglomerular mesangial cells Granular cells

Question 31

What three things stimulate rennin release?

Answer 31

Hypotension in the renal artery Stimulation of renal sympathetic nerves Decreased sodium in the renal tubular fluid (sensed by the macula densa)

Question 32

When is ANP released?

Answer 32

Released in response to atrial distention

Question 33

What does ANP do?

Answer 33

Causes the excretion of salt and water therefore reducing the blood volume and pressure. Acts as a vasodilator. Decreases rennin release

Question 34

What is another name for ADH?

Answer 34

Vasopressin

Question 35

Where is ADH synthesized?

Answer 35

HYpothalamus

Question 36

Where is ADH stored?

Answer 36

Pituitary gland

Question 37

What stimulates secretion of ADH?

Answer 37

Reduced extracellular fluid volume | Increase extracellular fluid osmolarity

Question 38

How is plasma osmolarity monitored?

Answer 38

Osmoreceptors

Question 39

How does ADH increase BP?

Answer 39

Acts on the kidney tubules to increase the reabsorption of water This increases extracellular output and blood pressure

Question 40

What affect does ADH have on blood vessels?

Answer 40

Vasocontriction

Question 41

What is the relationship between blood viscosity and length of blood vessel?

Answer 41

Directly proportional to the power of 4

Question 42

What is the relationship between blood viscosity and radius of the blood vessel?

Answer 42

Inversely proportional tot eh power of 4

Question 43

Which adrenoceptor acts on vascular smooth muscle?

Answer 43

alpha

Question 44

What is the vasomotor tone?

Answer 44

Blood vessels are partially constricted at rest

Question 45

What causes the vasomotor tone?

Answer 45

Tonic discharge of sympathetic nerves resulting in continuous release of noradrenaline

Question 46

What will increase the vasomotor tone?

Answer 46

Sympathetic stimulation

Question 47

What adrenoceptor causes vasodilation when acted on by noradrenaline?

Answer 47

beta

Question 48

Where are the alpha receptors situated?

Answer 48

Skin, gut, kidney arterioles

Question 49

Where are the beta receptors located?

Answer 49

Cardiac and skeletal smooth muscle

Question 50

True or false: Intrinsic controls of vasculature can over-ride extrinsic ones?

Answer 50

True

Question 51

What vessels contain most of the blood volume under resting conditions?

Answer 51

Capacitance vessels eg the veins

Question 52

What local metabolites cause vasodilation?

Answer 52

``` Decreased PO2 Decreased CO2 Decreased pH Increased extra cellular K Increased ECF osmolarity Adenosine release ```

Question 53

What physical factors cause vasodilation

Answer 53

Warmth Decreased MAP (myogenic) Sheer stress

Question 54

What is the myogenic affect?

Answer 54

If the MAP rises- vasoconstirction occurs to limit flow and vice versa

Question 55

What humoral agents cause vasodilation

Answer 55

Histamine Prostoglandin Bradykinin Nitric oxide

Question 56

Where is NO produced

Answer 56

Endothelium

Question 57

What humoral agents cause vasoconstriction

Answer 57

Seratonin Thromboxane A2 Leukotrienes Endothelin

Question 58

What physical factors cause vasocontriction

Answer 58

Cold | Increase MAP

Question 59

What amino acid is NO produced from

Answer 59

L-argenine

Question 60

Which enzyme catalyses the formation of nitric oxide

Answer 60

NOS

Question 61

What is the relatioship between sheer stress and NO production

Answer 61

Sheer stress increases calcium release which activates NOS and results in increase NO

Question 62

What is the consequence of an increased venomotor tone?

Answer 62

increased venous return to the heart

Question 63

What is the acute CVS response to exercise?

Answer 63

``` Increased sympathetic tone Increased HR and SV Vasodilation to smooth mucles and cardiac Vasocontriction to gut and kidney etc Increase SBP but decreased TPR and DBP Post exercise hypotension ```

Question 64

What is the chronic CVS response to exercise?

Answer 64

Reduced BP