Cardiovascular (Peter) Flashcards Preview

medscionefourtwo > Cardiovascular (Peter) > Flashcards

Flashcards in Cardiovascular (Peter) Deck (75)
Loading flashcards...
1
Q

distribution of blood by volume

A

9% pulmonary circuit
7% inside the heart
84% systemic circuit

2
Q

pressure and resistance in the pulmonary circuit vs systemic circuit

A

medium resistance and pressure in the pulmonary circuit vs. high resistance and pressure in the systemic circuit

3
Q

inlet valves prevent

A

high-pressure blood in the pumping chamber from returning to the veins

4
Q

function of the appendage/auricle

A

increase the capacity of the atria

5
Q

how does having the inlet and outlet on the same end of the heart improve its function?

A

chamber can shorten in length as well as in width

6
Q

pulmonary vein orientation vs vena cava

A

pulmonary vein(s) are very horizontal while the vena cava is very vertical

7
Q

the _____ of the heart is the pointed tip of the left ventricle. At the opposite end from the _____ is the _____.

A

the apex of the heart is the pointed tip of the left ventricle. At the opposite end from the apex is the base.

8
Q

peak pressure of…

  1. left atrium
  2. left ventricle
  3. right atrium
  4. right ventricle
A
  1. left atrium = 8mmHg
  2. left ventricle = 120mmHg
  3. right atrium = 5mmHg
  4. right ventricle = 27mmHg
9
Q

inlet valves constructed of

A

fibrous connective tissue

10
Q

fate of the blood from the gut

A

the deoxygenated, nutrient rich blood travels to the liver via the hepatic portal vein

11
Q

function of chordae tendineae

A

prevent the bicuspid and tricuspid valve from bursting upwards into the atrium during systole

12
Q

name of the ligament between the aorta and pulmonary trunk

A

ligamentum arteriosum

13
Q

names and location of the atrioventricular valves

A

bicuspid/mitral on the left

tricuspid on the right

14
Q

chordae tendineae are loose during

A

distole

15
Q

ratio of size of ventricles in a foetus

A

the same boiiiiiiiiiiiiiiii

16
Q

outlet valves names and location

A

SEMILUNAR VALVES
pulmonary on the right
aortic on the left

17
Q

ratio of peak pressure in the LV:RV

A

5:1

18
Q

ratio of wall thickness in the LV:RV

A

3:1

19
Q

openings to the coronary arteries

A

in the aorta, just after the semilunar aortic valve

20
Q

how many cusps in the outlet valves? cords or nah?

A

3 cusps, no cords

21
Q

The ____ of the heart points inferiorly and anteriorly to the left. About 1/3 of the mass of the heart lies to the _____ of the midline of the body and about 2/3 to the _____. The right border of the heart is formed mainly by the ____ ______. The inferior border is formed mainly by the _____ ______. The left border is formed mainly by the _____ ______.

A

The apex of the heart points inferiorly and anteriorly to the left. About 1/3 of the mass of the heart lies to the right of the midline of the body and about 2/3 to the left. The right border of the heart is formed mainly by the right atrium. The inferior border is formed mainly by the right ventricle. The left border is formed mainly by the left ventricle.

22
Q

Pericardium made of (inner and outer wall)

A

single layer of squamous mesothelial cells

23
Q

what constitutes the heart wall

A

endocardium - myocardium - epicardium (visceral pericardium)

24
Q

what constitutes the pericardium

A

epicardium (visceral pericardium) - pericardial space (serous fluid) - parietal pericardium - fibrous pericardium (tough fibrous sac)

25
Q

cardiac tamponade

A

blood in the pericardial space

26
Q

fibrous skeleton of the heart structure

A

2 complete fibrous rings around the mitral and aortic valves and 1 incomplete ring around the tricuspid valve

27
Q

pericardium function

A

no friction when the heart beats

28
Q

what is present where the fibrous skeleton is incomplete?

A

fatty connective tissue

29
Q

relative speed of conduction and reason:

  1. SA node - Atrial myocardium
  2. AV node
  3. AV bundle (bundle of his) - Purkinje fibre
A
  1. SA node - Atrial myocardium = SLOW 0.5m/s
    - atrial contraction
  2. AV node = VERY SLOW 0.05m/s
    - 100ms delay
  3. AV bundle (bundle of his) - Purkinje fibre = FAST 5m/s
    - even ventricular constriction (systole)
30
Q

ventricular filling

A
  • DIASTOLE.
  • starts when pressure in the ventricle drops below the pressure in the atrium (less than 5mmHg).
  • Mitral valve opens quietly and blood enters the ventricle to ~80% of its capacity.
  • Accounts for half the total cycle time
31
Q

the cardiac cycle duration

A

1 second

32
Q

Atrial contraction

A

left atrium contracts and completes the filling of the left ventricle. Tops up 20% volume.

33
Q

during atrial contraction, the increase in pressure in the left atrium is relatively small due to…

A
  1. atrial muscle layer is thin

2. there are no valves preventing blood flowing back into the pulmonary veins

34
Q

Isovolumetric ventricular contraction

A
  • SYSTOLE
  • mitral valve closes = first heart sound (“lub”)
  • ventricular pressure is increasing but still less than that in the aorta
  • aortic valve remains closed
  • 0.05 seconds
35
Q

ventricular ejection

A
  • SYSTOLE continues
  • ventricular pressure is greater than pressure in the aorta
  • aortic valve opens quietly
  • blood leaves the ventricle
  • pressure in the aorta and ventricle continues to rise
36
Q

why does pressure in the aorta and ventricle continues to rise during ventricular ejection?

A

Because blood is being ejected into the aorta faster than it can run-off into the distributing arteries. Thus eventually levels-off then decreases

37
Q

Isovolumetric ventricular relaxation

A
  • ventricle relaxes
  • sudden drop in ventricle pressure
  • flow reverses in the aorta
  • aortic valve fills with blood and closes = second heart sound (“dub”
  • mitral valve closed because, even though it is falling, pressure in the ventricle is still higher than the atrium
  • ventricle isolated from the rest of the circulation
  • 0.05 seconds
  • preceds ventricular filling
38
Q

2 functions of the fibrous skeleton

A
  1. support and anchor the valve leaflets to the heart wall

2. insulate ventricles from SA node

39
Q

which valve has no fibrous skeleton?

A

pulmonary

40
Q

maximuma and minimum blood volume of the left ventricle

A

120 max

40mL min

41
Q

when is the pressure in the aorta at its lowest? what is this value?

A

just before ventricular ejection = 80mmHg

42
Q

blood leaving the ventricle referred to as…

A

bolus

43
Q

Function of elastic artery

A
  • near the heart.
  • during systole they store the bolus of blood leaving the ventricle.
  • during diastole they push blood out by elastic recoil
  • smooth the pulsatile flow of blood leaving the heart
44
Q

structure of elastic artery

A

many thin sheets of ELASTIN in the middle tunic.

Diameter the size of a finger

45
Q

Muscular artery function

A
  • distribute blood around the body at high pressure and to the lungs at medium pressure
  • rate of flow adjusted by using smooth muscle to vary the radius
46
Q

Flow and radius

A

flow is proportional to the fourth power of radius

47
Q

structure of muscular artery

A

many layers of circular smooth muscle wrapped around the vessel in the middle tunic (media).
Diameter the size of a pencil-pin

48
Q

3 layers of arteries

A
outer tunic (externa)
middle tunic (media)
inner tunic (interna - intima)
49
Q

arteriole function

A
  • control blood flow into the capillaries
  • largest drop in pressure
  • greatest resistance to flow
  • degree of constriction determines TOTAL PERIPHERAL RESISTANCE which itself affects MEAN ARTERIAL BLOOD PRESSURE
50
Q

Structure of arteriole

A

1-3 layers of circular smooth muscle in the middle tunic.
Thickest muscular wall relative to size than any other blood vessel.
Lined with endothelial cells.
Diameter the size of a hair.

51
Q

cardiohypertrophy

A

enlargement of the heart causes boot shape. In an x-ray a larger cardio-thoracic ratio is visible (~50%)

52
Q

aortic stenasis (narrowing)

A

often due to rheumatic fever - causes body to create antibodies which attack your own body tissue. In the case of the aortic valve it can recover but will be scarred and its integrity damaged. the valve is narrowed as a result and the left ventricle has to work harder.

53
Q

Capillary function

A
  • thin walled to allow exchange of gases, nutrients and wastes between blood and tissue fluid.
  • slow blood flow to allow time
  • leaky - plasma escapes to form interstitial/tissue fluid
54
Q

capillary structure

A
  • 9μm diameter, the same as a RBC
  • single layer of endothelium
  • external basement membrane
  • NO SMOOTH MUSCLE
  • NO CONNECTIVE TISSUE
55
Q

Venule function

A
  • low-pressure drain for capillary beds

- where WBCs leave blood circulation

56
Q

venule structure

A

small venules have usual endothelium + some connective tissue. Large venules have a single layer of smooth muscle.

57
Q

Vein function

A
  • low-pressure
  • drain blood back to atria (besides portal veins)
  • small pressure change causes large change in venous volume, therefore they act as a RESERVOIR WHICH STORES BLOOD
  • 64% of blood volume occurs in systemic veins and venules
58
Q

vein structure

A
  • thin and soft walls

- larger veins have valves to prevent backflow

59
Q

angina

A

chest pain

60
Q

ischemia

A

low oxygen

61
Q

anastomoses

A

artery-to-artery junctions

62
Q

clinical importance of cardiac veins

A

NONE

63
Q

if a coronary artery narrows to about 20% of its diameter by atheroma…

A

significant obstruction of blood flow to the myocardium which then runs low on oxygen (ischemia) causing angina. Severe ischemia can result in death (infarction).

64
Q

idiopathic

A

cause unable to be identified

65
Q

Dilated cardiomyopathy

A
  • cause often idiopathic - probably a viral infection
  • infected muscle fibres attacked by lymphocytes - many die or are weakened and slow to contract
  • left ventricle most affected because of high pressure
  • Left ventricle dilates (chamber enlarged but wall thickness remains the same)
  • fibrous ring supporting mitral valve stretches
  • mitral valve flaps no longer meet during systole, causing MITRAL REGURGITATION
66
Q

why does the left ventricle dilate?

A

due to the lengthening of the cardiac muscle fibres

67
Q

when the left ventricle dilates how is the thickness of the wall changed?

A

it doesn’t change. ratio of RV:LV remains at 1:3

68
Q

mitral regurgitation

A

blood regurgitates from the left ventricle into the left atrium during systole

69
Q

how does the regurgitated blood affect the pressure of the LA

A

increases

70
Q

Heart sound due to mitral regurgitation

A

Lub-shhhhh-dub (“shhhh” due to regurgitation)

71
Q

regurgitation =

A

backflow of blood

72
Q

in mitral regurgitation, the mitral valve is said to be…

A

incompetent

73
Q

BREATHLESSNESS

why does a problem on the left (systemic) side of the heart cause problems in the right (pulmonary circuit)?

A
  1. To maintain cardiac output the LV must pump a greater volume of blood
  2. Assuming the heart remains the same, LV volume at the end of filling (diastole) must increase
  3. in order to fill the ventricle the LA works harder
  4. LA pressure increases
  5. Pulmonary venous pressure increases
  6. Pulmonary capillary pressure increases
  7. pulmonary capillary leakage increases
  8. Lungs heavier and wetter
  9. Lungs more rigid
  10. Breathing requires more muscular work
74
Q

in mitral regurgitation, how much of the blood ejected by the LV is actually regurgitated into the LA?

A

as much as half. It returns to the LV during the next diastole along with fresh blood.

75
Q

Dyspnoea

A

discomfort during breathing, consciousness of laboured breathing.