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Flashcards in Cardiovascular Deck (74):
1

What is blood pressure?

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

2

What is the systemic systolic arterial blood pressure?

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 140 mm Hg under resting conditions

3

What is the systemic diastolic blood pressure?

The pressure exerted by the blood on the walls of the aorta and systemic arteries when the heart relaxes”: should not normally reach or exceed 90 mm Hg under resting conditions

4

What is the normal flow of blood in arteries called?

Laminar flow

5

What sounds are heard in laminar flow

No sounds

6

What is the first Korotkoff sound?

The peak systolic pressure

7

What are the 2nd and 3rd Korotkoff sounds?

Intermittent sounds are heard as a result of turbulent spurts of flow cyclically exceeding cuff pressure

8

What pressure do korotkoff sounds 1-3 become audible?

Between 120mmHg and 80mmHg

9

What is the 4th Korotkoff sound?

The last sound, heard at minimum diastolic pressure. (muffled/muted)

10

What is the 5th Korotkoff sound?

No sound is heard at this point because of uninterrupted, smooth, laminar flow.

At this point diastolic pressure is recorded

11

When are the 4th and 5th Korotkoff sounds present?

When cuff pressure is less than 80mmHg.

12

What is the right atrial pressure?

Close to zero

13

What does the pressure gradient between the aorta and the right atrium responsible for?

Driving blood around the systemic circulation

14

What is the formula for the pressure gradient between the AO and RA?

Pressure Gradient= Mean Arterial Pressure (MAP) - Central Venous (right atrial) pressure (CVP

15

What is mean arterial blood pressure? (MAP)

Mean Arterial blood pressure is the average arterial blood pressure during a single cardiac cycle, which involves contraction and relaxation of the heart.

16

What is longer? Systolic or diastolic?

Diastolic is almost twice as long

17

What formula can be used to estimate MAP?

[(2 x Diastolic pressure) + systolic pressure]

3

18

What is another way to estimate MAP?

by adding DBP + 1/3rd of pulse pressure

MAP=DBP+1/3

(difference between SBP and DBP)

19

What is the normal range for MAP?

70-105 mmHg

 

MAP of at least 60 mmHg is needed to perfuse the coronary arteries, brain and kidneys

20

What is the relationship between;

  • MAP
  • CO
  • TPR

MAP= CO x TPR

21

What is CO?

CO is cardiac output, the vlume pumped by each ventricle of the the heart per minute

22

How can we calculate CO?

CO= SV x HR

23

What is SV?

Stroke volume (SV) is the volume of blood pumped by each ventricle of the heart per heart beat

24

What is TPR?

Total peripheral resistance is the sum of resistance of all peripheral vasculature in the systemic circulation.

25

What are the major resistance vessels?

The arterioles

26

What is the baroreceptor reflex responsible for regulating?

Short term regulation of mean arterial blood pressure

27

Where are the baroreceptors and how do each group send signals to the brain?

  • aortic arch- via Xth CN
  • carotid sinus- via IXth CN

28

What is postural hypotension?

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

29

What happens to the baroreceptor reflex if there is an;

  1. increase in ABP
  2. decrease in ABP

  1. increases the rate of firing
  2. decreases the rate of firing

30

What is the ECFV?

extracellular fluid volume is the fluid which bathes the cells and acts as the go-beteen the blood and body cells

31

How can ECFV be calculated?

ECFV = PV + IFV

PV (plasma volume)

IFV (interstitial fluid volume)

32

What happens if plasma volume falls?

Compensatory mechanisms shifts fluid from the interstitial compartment to the plasma compartment.

33

What two factors affect ECFV?

  1. Water excess or deficit
  2. Naexcess or deficit

34

What do hormones regulate?

They act as effectors tp regulate the ECFV (including PV) by regulating the water and salt balance in our bodies.

35

What hormones regulate ECFV

  1. The renin-angiotensin-aldosterone system (RAAS)
  2. Atrial Natriuretic Peptise- ANP
  3. Antidiuretic Hormone (Arginine Vasopressin) ADH

36

What does RAAS regulate?

Plasma volume and TPR, hence MAP

37

Where is renin released from and what does it stimulate?

The kidneys, it stimulates the formation of angiotensin I in the blood from angiotensin II produced by the liver.

38

What converts angiotensin I to angiotensin II and where is it produced?

Angiotensin converting enzyme- ACE (produced by pulmonary vascular epithelium)

39

What does angiotensin II stimulate the release of and where from?

Aldosterone from the afrenal cortex

40

What does aldosterone cause 

Systemic vasoconstriction- increasing TPR and stimilating thirst and ADH release, contributing to increasing plasma volume

41

What is aldosterone?

A steroid hormone responsible for increasing sodium and water retention in the kidneys- increasing plasma volume

42

Which mechanisms stimulate the release of renin from the juxtaglomerular apparatus in the kidneys?

  1. renal artery hypotension- caused by systemic hypotension (reducing BP)
  2. Stimulation of renal sympathetic nerves
  3. Decreased [Na+] in renal tubular fluid- sensed by macula densa of kidney tubules

43

What is the role of Atrial Natruiretic Peptide?

It is released in response to hypervolaemic states, causing excretion of salt and water in the kidneyrs, thereby reducing blood volume and blood presure

44

What does Atrial Natruiretic Peptide act as?

A vasodilator and a counter-regulatory mechanism for the renin-angiotensin-aldosterone system (RAAS)

45

What effect does Atrial Natruiretic Peptide have on renin release?

It decreases renin release

46

Where is vasopressin (ADH) synthesised and stored?

Synthesised- The hypothalamus

Stored- Posterior Pituitary

47

What two factors stimulate ADH release?

  1. Reduced extracellular fluid volume
  2. Increased extracellular fluid osmolarity

(the normal osmolarity of extracellular fluid is about 280milli-osmoles/l)

48

Where is plasma osmolarity monitores and what happens if it is increased?

It is monitored by osmoreceptors- mainly in the brain- in close proximity to the hypothalamus- increased plasma osmolarity will stimulate the release of ADH

49

What does ADH do?

Acts in the kidney tubules to increase the reabsorption of water (conserve water)

50

What does increased ADH do to ECFV and PV

It would increase them therefore increase CO and BP

51

What does ADH so to blood vessels and what is the significance of this?

Causes vasocontriction and increases TPR and BP

52

What are capillary walls composed of?

Single layer of endothelial cells

53

What does the capillary wall allow?

  • rapid exchange of 
    • gases
    • water
    • solutes with interstitial fluid
  • Delivery of Oto cells
  • Removal of metabolites from cells

54

What regulates blood flow in most tissues?

What is the other method of regulating capillary blood flow?

Terminal arterioles regulate regional blood flow to the capillary bed

precapillary sphincters regulate flow in a few tissues

55

What law does the movement of gases and solutes follow?

Ficks law of diffusion

56

How do lipid soluble substances cross the membrane?

They go through the endothelial cells

57

How do water soluble substances cross the membrane?

They go through water-filled pores

58

How is transcapillary fluid flow driven?

By pressure gradients across the capillary wall

59

What forces are involved in transcapillary fluid flow?

(starling forces)

Forces favouring filtration

  • Pc capillary hydrostatic pressure
  • π- interstitial fluid osmotic pressure

Forces opposing filtration

  • πc -capillary osmotic pressure
  • P- interstitial fluid hydrostatic pressure (-ve in some tissues)

60

What do starling forces favour at the arteriolar and venular end respectively?

Filtration

and 

reabsorption

61

How is excess fluid returned to the circulation?

Via the lymphatics as lymph

62

What is the normal range of pulmonary capillary hydrostatic pressure?

~8-11 mmHg

63

What is the capillary osmotic pressure?

25 mmHg

64

What is the definition of oedema?

Accumulation of fluid in interstitial space

65

What are the causes of oedema?

  1. Raised capillary pressure
  2. Reduced plasma osmotic pressure
  3. Lymphatic insufficiency
  4. Changes in capillary permeability

66

What causes raised capillary pressure?

arteriolar dilatation

raised venous pressure;

prolonged standing

right ventricular failure

left ventricular failure

67

Where will oedema caused by left ventricular and right ventricualr failure gather respectively?

Pulmonary oedema

Peripheral oedema (ankle, sacral)

68

What reduces plasma osmotic pressure?

malnutrition

protein malabsorption

excessive renal excretion of protein

hepatic failure

69

What causes lymphatic insufficiency?

lymph node damage

filariasis- elephantiasis

70

What can change capillary permeability?

Inflammation

histamine increases leakage of protein

71

Where is the fluid situated in pulmonary oedema?

Interstitial and intraalveolar lung spaces

72

What manifests from left ventricular failure and how can it be diagnosed?

SOB

Crepitations in auscultations of lung bases

Chest X-ray shows haziness in perihilar region

73

Where is pitting oedema found?

Right ventricular failure;

Ankles 

Sacrum

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