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Cardiovascular system > Lecture 3- Haemodynamics > Flashcards

Lecture 3- Haemodynamics Flashcards

1
Q

haemodynamics definition

A

can be defined as the factors that govern blood flow (the movement of fluid between two points) and is dependent upon the relationship between cardiac output, blood pressure and resistance.

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2
Q

what dictates delivery of blood

A

metabolic demand

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3
Q

blood moves from

A

relative high to low pressure regions

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4
Q

blood is made up of

A

plasma, serum and red blood cells

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5
Q

serum is

A

plasma without clotting factro

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6
Q

fluid collected from unclotted blood is called

A

plasma

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7
Q

fluid collected from clotted blood is called

A

serum

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8
Q

what can cause blood viscosity (thickness) to change

A

Polcythaemia (RBC) Thrombocythameia (platelets) Leukaemia (WBC)

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9
Q

viscous blood leads to

A

dry gangrene in peripheries

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10
Q

minor changes ot plasma viscosity arise due to

A

acute phase plasma proteins

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11
Q

examples of acute phase plasma proteins

A

 Fibrinogen  Compliment  C-reactive protein (CRP)

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12
Q

mean arterial pressure (MAP) =

A

CO X TPR

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13
Q

pulse pressure=

A

Systolic pressure (SBP)- DBP

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14
Q

CO=

A

HR xSV

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15
Q

thickest vasculature and widest lumen

A

aorta and vena cava

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16
Q

thinnest vasculature and narrowest lumen

A

capillary and venules

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17
Q

blood usually flows through vessels in a

A

very organised and streamline fashion- laminar flow

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18
Q

laminar flow

A

Is smooth, silent, maintains energy and typical of most arteries, arterioles, venues and veins

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19
Q

turbulent flow

A

disorganised, energy lost, not in streamline, irregular movement of blood, noisy.

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20
Q

pressur and turbulence

A

Pressure increase beyond which flow can match its linearly

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21
Q

turbulent flow occurs due to

A

stenosis- occlusion of blood vessel

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22
Q

direct measurement of blood pressure is

A

precise but invasive and technically demanding

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23
Q

indirect measurement of blood pressure is

A

convenient, non invasive and can be carried out by anyone with minimal training

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24
Q

principles of indirect blood flow rely on

A

changes in type of flow- laminar and turbulent

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25
Q

thrill

A

is what can be felt when stenosis causes turbulent flow

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26
Q

bruit

A

is what can be heard when stenosis causes turbulent flow

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27
Q

creating turbulent flow during auscultation

A

Changes from laminar to turbulent flow create sound which can be heard and used to estimate BP –>Korotkoff sounds

28
Q

Korotkoff sounds

A

are produced underneath the distal half of the blood pressure cuff. The sounds appear when cuff pressures are between systolic and diastolic blood pressure, because the underlying artery is collapsing completely and then reopening with each heartbeat.

29
Q

outline how BP is estimated by auscultation

A
  1. Place the cuff over the bare upper arm with the artery mark positioned directly over the brachial artery.
  2. Measure in both arms, often a difference- use the higher as reference arm
  3. Sat comfortably, upright with legs uncrossed and flat on the ground
  4. Arm supported
  5. Repeated several times- mean taken of two closest values
  6. Measurement taken at the level of heart (brachial) and RESTING
30
Q

if cuff is too small

A

overestimate BP

31
Q

if cuff is too big

A

underestimate BP

32
Q

blood flow refers to the

A

movement of blood through a vessel, tissue or organ (expressed in volume of blood per unit of time (L/min))

33
Q

blood flow is initiated by the

A

contraction of the ventricles

34
Q

ventricular contraction ejects blood into he

A

major arteries resulting in flow from region of higher pressure to region of lower pressure as blood encounters smaller arteries, arterioles, then capillaries, then venues and veins for the nervous system

35
Q

flow -

A

L/min

36
Q

pressure =

A

force per unit area - mmHg (SI unit is pascal)

37
Q

pressure is highest in

A

arteries (nearest aorta) and lowest in veins

38
Q

resistance is the

A

measure of ease of flow (TPR)

39
Q

higher the TPR

A

the higher the arterial pressure - narrow lumen - vasoconstriction

40
Q

lower pressure

A

wider lumen

41
Q

the lower the resistance =

A

the higher the flow at said perfusion pressure

42
Q

the higher the resistance=

A

the lower the flow at said perfusion pressure

43
Q

resistance to flow factors (3)

A

diameter length of vessel viscosity

44
Q

resistance in pulmonary circulation is

A

much lower than systemic system due to having shorter and wider vessels

45
Q

resistance in aorta is

A

low- large diameter and relatively short in length - highest pressure

46
Q

Pressure in small arteries and arterioles contribute the

A

greatest component of TPR –> arterioles are the seat of TPR

47
Q

velocity=

A

distance fluid moves in a given time (cm/s)

48
Q

velocity reduces from

A

the aorta to the capillaries - gives capillaries optimum time for diffusion of nutrients

49
Q

velocity and area in capillaries

A

cross-sectional area is vast (thousand time greater than aorta) - velocity of capillary level much slower than aorta - velocity increases again as vessels merge into larger veins and into vena cava

50
Q

mean arterial pressure (MAP) represents

A

Represents the “average” pressure of blood in the arteries, that is, the average force driving blood into vessels that serve the tissues.

51
Q

MAP equation

A

diastolic BP + ((systolic-diastolic BP) / 3)

52
Q

normal range of MAP

A

70–110 mm Hg

53
Q

if BP falls below

A

60mmHg for an extended time, BP will. not be enough to perfuse organs- ischameai

54
Q

blood pressure is

A

The force exerted by blood upon the walls of the blood vessels or the chambers of the heart.

55
Q

where is blood pressure usually obtained from

A

brachial artery

56
Q

systolic pressure

A

(typically around 120 mm Hg) reflects the arterial pressure resulting from the ejection of blood during ventricular contraction or systole

57
Q

diastolic pressure

A

(around 80 mm Hg) represents the arterial pressure of blood during ventricular relaxation or diastole

58
Q

pulse

A

Shock wave that arrives slightly before the blood itself. After blood is ejected from the heart, elastic fibers in the arteries help maintain a high-pressure gradient as they expand to accommodate the blood, then recoil. This expansion and recoiling effect, known as the pulse, can be palpated manually or measured electronically.

59
Q

pulse indicates

A

heart rate

60
Q

what can cause a hounding pulse (indicates strength of ventricular contraction and CO)

A

heart block (Bradycardia) vasodilation (decrease TPR) Elite athletes (systole increases and diastolic decreases)

61
Q

pulse pressure

A

difference between the systolic pressure and the diastolic pressure is the pulse pressure. For example, an individual with a systolic pressure of 120 mm Hg and a diastolic pressure of 80 mm Hg would have a pulse pressure of 40 mmHg.

62
Q

PP =

A

SBP-DBP

63
Q

Pulse pressur should be at least

A

25% of the systolic pressure

64
Q

low or narrow PP

A

 In patients with a low stroke volume, which may be seen in congestive heart failure, stenosis of the aortic valve, or significant blood loss following trauma.

65
Q

high or wide pulse pressure

A

is common in healthy people following strenuous exercise, when their resting pulse pressure of 30–40 mm Hg may increase temporarily to 100 mm Hg as stroke volume increases.

66
Q

persistently high pulse pressure above 100 mm Hg

A

may indicate excessive resistance in the arteries and can be caused by a variety of disorders- can degrade the heart, brain, and kidneys, and warrant medical treatment.

Cardiovascular system (30 decks)

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