CVS Flashcards Preview

ESA 4 revision > CVS > Flashcards

Flashcards in CVS Deck (157):
1

Functions of CVS you always forget?

Infrastructure for immune system
Thermoregulation

2

Feature of metabolically active tissues that aid diffusion?

High capillary density leading to greater perfusion and SA

3

What molecules diffuse easiest?

Small, uncharged polar molecules

4

Nature of barrier?

Number of pores and size

5

Maintenance of conc gradient t?

constant high perfusion flow

6

What is in blood?

RBCs,
WBCs
Platelets

7

What is blood flow?

5L/min

8

Constant flow to which organs?

Brain & kidneys

9

What type of verses have faster flow?

Low cross-sectional area, like veins

10

Feature of capillaries affecting flow?

Many branches, increasing cross-sectional area of vascular bed > slows down flow for exchange

11

What are arteries?

resistance vessels regulating flow to direct perfusion

12

What are end arteries?

terminal arteries supplying blood to a body part without significant collateral circulation

13

Examples of end arteries?

Splenic, coronary and renal

14

What are elastic arteries?

large & conducting

15

What are the layers of arteries?

Tunica intima - endothelium
Tunica media - smooth muscle & collagen
Tunica adventitia - CT, vasa vasorum and nerves

16

Describe elastic arteries?

TI - elastic lamina
TM - fenestrated elastic membranes
TA - thin fibroelastic connective tissue with nerves & vast vasorum

17

What are muscular arteries?

Medium sized & distributing

18

Describe muscular arteries?

circularly arranged smooth muscle. Contain nerve endings for sympathetic stimulation of vasoconstriction

19

What are arterioles?

Narrowest arteries with thin CT, single smooth muscle layer and thin layer of fibroblasts

Able to constrict and dilate

20

What are Metarterioles?

Arteries supplying blood to a capillary bed with non-continuous regions of smooth muscles = pre-capillary sphincters

21

What do pre-capillary sphincters do?

regulate flow to capillary beds

CONTRACTED = REDUCED CAPILLARY FLOW

22

Features of capillaries?

Mono-layer of endothelium and basement membrane

RBC fills entire lumen

Low blood velocity

23

Types of capillaries?

Continuous - tight cell junctions (muscle, exocrine, lungs)

Fenestrated - interruptions of endothelium with thin diaphragms (endocrine, glomerulus and gut)

Sinusoidal/ discontinuous - gaps in wall for whole cells to more (liver, spleen and bone marrow)

24

Features of post-capillary venuoles?

More permeable than capillaries with lower pressure:

Tissue fluid drains back into vessels.

Site of emigration of leukocytes from blood

25

What are veins?

Capacitance vessels - distend to cope with changes to CO

26

Features of veins?

Thin and distend able walls = reservoir

Low pressure with thin smooth muscle

Valves to prevent retrograde flow. Work with muscles in legs to propel blood to heart

Large diameters

27

What are venue comitantes?

2 paired deep veins accompanying smaller arteries wrapped in a vascular sheath.

The pulsing artery helps venous return.

28

What is ventricular systole pressure?

120mmHg

29

What is ventricular diastole pressure?

80mmHg

30

What happens to BP as you go further from the heart?

Decreases with distance

Fluctuating in sync with ventricular systole & diastole > drops are capillaries > constant low at veins

31

Describe cardiac muscle?

Discrete cells connected electrically with intercalated discs.

Involuntary, striated and myogenic branching muscle

1/2 central nuclei per cell

Diad (t-tubules) occurs at Z-line

32

How long is systole?

280 ms

33

How long is diastole?

700ms

34

What is pulse pressure?

Systolic = Diastolic pressure = 40mmHg

35

What is Mean Arterial Blood Pressure?

Diastole + 1/3 systolic pressure

36

What are the names of heart valves?

Atrioventricular:
Tricuspid (RH)
Bicuspid (LH)

Outflow:
Pulmonary
Aortic

37

What is the SAN?

Sino-atrial node in the RA

38

How long is the delay at the AVN?

120ms

39

What is the AVN?

Atrio-ventricular node

40

What direction do the ventricles contract?

Endocardium to epicardium, from the apex up

41

What is the tissue in the septum?

Bundle of His

42

How doe the ventricular muscles contract?

figure of 8 contraction movement for most effective ejection

43

What are the important stages of cardiac contraction?

Rapid filling phase
Isovolumetric contraction
Rapid ejection phase
Isovolumetric relaxation

44

What is the 1st heart sound - S1?

Atrioventricular valves closing (beginning of systole)

45

What is the 2nd heart sound - S2?

Outflow valves closing (end of systole)

46

What creates murmurs?

Turbulent flow through valves:
narrowed valve or back flow through incompetent valve

47

What is the most common congenital heart defect?

Ventricular septal defect
VSD

48

Which Congenital Heart defects are acyanotic?

Atrial septal defect
Patent Foramen Ovale
Ventricular septal defect
Patent Ductus Arteriosus
Coarctation of Aorta

49

Which Congenital heart defects are cyanotic?

Tetralogy of Fallot
Tricuspid atresia
Transposition of the great arteries
Hypoplastic left heart

50

Why are Patent Foramen Ovale not a true ASD?

Clinically silent as high LA pressure functionally closes flap valve

51

What is dangerous about PFOs?

Route for venous embolism to reach systemic circ. if RA pressure transiently > LA pressure

52

Most common site for VSD?

membranous portion of septum

53

What is the ductus arteriosus?

In foetuses, shunt from pulmonary art. to aorta due to underdeveloped lungs. Shunt closes after birth.

Patent DA leads to blood flowing from aorta --> pulmonary artery creating a mechanical murmer

54

What is the consequence of PDA?

Increase volume cause vascular remodelling of pulm. circa > increase in resistance > increase pressure > revere direction from pulm. to aorta = Eisenmenger Syndrome

55

What is coarctaction of the aorta?

narrowing of the lumen at the ligament arteriosum (former DA) increasing resistance leading to Left Ventricular Hypertrophy.

56

In CoA, why are some body regions under-perfused?

Coarctation occurs after B,C,S arteries branching, hence not compromised. But the rest of the flow is compromised - weak and delayed femoral pulses, upper limb hypertension.

57

What are the 4 lesions in Tetralogy of Fallot?

VSD
Overriding Aorta
Pulmonary stenosis
Right ventricular hypertrophy

Pulmonary stenosis > RVH due to resistance > increased RV pressure > blood shunt R-->L due to VSD & Overriding Aorta > mixture of deoxy & oxy blood in systemic circ > cyanosis

58

What is tricuspid atresia?

Lack of development hence X inlet into RV.

Need to have an ASD or PFO (shunting RA --> LA) and VSD (shunting LV --> RV for oxygenation)

59

What is Transposition of the Great Arteries?

Incompatible with life, unless there is a shunt - Ductus Arteriosus or ASD

60

What is Hypoplastic Left Heart?

Underdeveloped LV and Ascending aorta

Requires a PFO or ASD, and a PDA

61

Where is the Sympathetic Nervous System outflow?

Thoraco-lumbar

62

Sympathetic pre & post-ganglionic lengths?

Short pre
Long post

63

What type of neurones are sympathetic pre-gang?

Cholinergic releasing nicotinic Ach

64

What type of neurones are sympathetic post-gang?

Noradrenergic releasing NA to either Alpha 1/2 or Beta 1/3

65

Where is the parasympathetic Nervous System outflow?

Cranio-sacral

66

Parasympathetic pre & post-ganglionic lengths?

Long pre
Short post

67

What type of neurones are parasympathetic pre-gang?

Nicotinic cholinergic

68

What type of neurones are parasympathetic post-gang?

muscarinic cholinergic --> G-protein coupled receptors

69

What are the receptors of the heart?

Symp = B1

Parasym = M2

70

What are the receptors of the airways?

Symp = B2

Parasym = M3

71

What are the receptors of the pupils?

Symp = A1 --> dilation

Parasym = M3 --> constriction

72

What are the receptors of the sweat glands?

Symp:
Localised secretion = A1
General secretion = M3

No parasymp.

73

What signals go to beta-adrenoreceptors?

Adrenaline or Noradrenaline

74

What protein and effector occurs at Beta-adrenoceptors?

Gs --> stim. adenylyl cyclase

75

What signals go to Muscarinic receptors?

muscarinic Acetylecholine

76

What protein and effector occurs at M3 receptors?

Gq --> stim. phospolipase C > smooth muscle contraction

77

What protein and effector occurs at M2 receptors?

Gi --> inhibits adenylyl cyclase

78

Describe the relationship between sympathetic NS and blood vessels?

Innervates smooth muscle in the wall of vessels and cause vasoconstriction via A1 receptors.

Constant sympathetic stimulation = vasomotor tone. Less symp. stim = vasodilatation,
More symp. stim = vasoconstriction

79

What is the vasomotor tone of skin?

High

arterioles, pre-capillary sphincters and artery-venous anastomoses are shut

80

What is the vasomotor tone of skeletal muscle?

High at rest
Antagonised by vasodilator metabolites in exercise

81

How is distribution of blood in the CVS controlled?

Balance between sympathetic vasoconstriction tone and vasodilator metabolites

82

Where do the symp & parasymp. fibres innervate in the heart?

Both to SA and AV nodes

Symp also to ventricular myocytes to increase FoC --> increase CO

83

What controls the symp/parasym stimulation?

Baroreceptors in the arch of the aorta & carotid sinuses --> sending signals via hypoglossal nerve

84

What is HR without parasymp?

100BPM

85

How does the heart increase in rate?

1) reduce parasymp stim
2) increase symp. swim

86

What are all the signals that act of the heart?

Increase rate & FoC = Noradrenaline from post-gang sympathetic fibres & Adrenaline from Adrenal Glands acting on B1 receptors

Decrease HR & FoC = mAch from parasym. fibres acting on M2 receptors

87

Define FLOW

volume of fluid passing a given point per unit of time

Flow = Volume/Time

88

Define VELOCITY

rate of movement of fluid particles along a tube

Velocity = Distance/Time

89

What is LAMINAR FLOW?

Gradient of velocity, highest in the centre and stationary at the edge.
Most blood vessels have laminar flow

90

What is TURBULENT FLOW?

Increased mean velocity > gradient breaks down ? layers of fluid move over each other > tumble over each other > increased flow resistance

91

What is VISCOSITY?

The extent that fluid layers slide over each other.

High viscosity = more overlap and slow central layer flow

Low viscosity = less overlap, fast central layer flow

92

Relationship between diameter and flow?

The wider the tube, the faster the central layers flow. Mean velocity = proportional to cross sectional area of tube

93

What is resistance and it's relationship to flow?

Pressure = Flow X Resistance

R increases with viscosity (thicker blood)

R decreases with greater diameter - harder to flow in small vessels

94

Vessels in series affect on resistance?

Add together

95

Vessels in parallel affect on resistance?

Decreased, as more that 1 path for flow

96

If the heart pumps more blood, but resistance is the same, what happens to pressure?

PRESSURE RISES

97

Describe how the distensibility of blood vessels affect flow and pressure?

vessel pressure exerts a transmural pressure causing the vessel to stretch.

Stretch > increased diameter > reduced resistance > increases flow.

Hence with increased pressure > stretch > increased flow

Low pressure > walls collapse > no flow

98

What affects systolic pressure?

FoC
TPR
Compliance of arteries

99

What affects diastolic pressure?

Systolic pressure
TPR

100

What is TPR?

Total Peripheral Resistance is the sum of the resistance of all the peripheral vasculature in the systemic circ.

101

What is the pulse wave?

The contraction of the ventricles propagated along the arteries

102

List vasodilator metabolites:

H+, adenosine and K+

103

What doe vasodilator metabolites do?

Relax the local smooth muscle > decrease resistance > increase flow

104

Whats reactive hyperaemia?

Cut off circ. to limb > cells continue metabolising > produce vasodilators which are not removed > circulation restored > dilated arterioles > max. blood flow

105

What s auto-regulation?

Organs automatically take the blood flow supply they require matching their demand, as long as arterial pressure is within a certain range

106

What is venous return?

Venous return = rate of flow back to the heart - determines CO

107

What is Central Venous Pressure?

Central Venous Pressure = pressure of the great veins supplying heart

108

what is stroke volume?

The differences between end diastolic & end systolic volume

109

Describe the relationship between venous pressure and ventricle filling?

The amount ventricles fill is determined by the venous pressure. Ventricle walls stretch to equal the venous pressure.

Higher VP = more heart filling in diastole = increased end diastolic volume.

End diastolic stretch of myocardium = Pre-load - determined by venous pressure

110

What is after load?

the pressure needed to expel blood through arteries

111

What is the Starling's curve?

The more the heart stretched, the harder it contracts giving a bigger stroke volume - shown by starling's curve.

If the heart is over-filled, the myocardium is overstretched.

Gradient = contractility of the heart, not FoC.

112

What is postural hypotension?

Failure of baroreceptor reflex.

Standing - blood pools in legs > reduced VP > reduced CO > reduced AP = both low VP & AP --> solved by increased HR (detected by baroreceptors) and increased TPR

113

When do coronary arteries fill with blood?

During diastole, via the left & right coronary sinuses.

Cardiac muscle = high capillary density for O2 delivery & constant NO production for keep basal flow high

114

What is angina?

Narrowest coronary artery.
Stress & cold causes sympathetic coronary vasocontriction, as well as extra O2 demand, as well as shorter diastole so reduced blood delivery

115

What is syncope?

Loss of consciousness

116

what is the cushion's reflex?

impaired blood flow to vasomotor control regions of brainstem (due to haemorrhage or tumour) leads to increased peripheral vasomotor activity increased art. BP > maintaining cerebral blood flow

117

How is blood supply to brain controlled/maintained?

Many anastomoses, myogenic auto-regulation (vasoconstriction with increased BP, vice versa), metabolic regulation - panic hyper vent > hypercapnia > cerebral vasoconstriction > dizziness & fainting
Areas with increased neural activity have increased blood flow as adenosine is a powerful vasodilator

118

Temperature regulation in skin?

Blood flows via atria-venous anastomoses to remove heat

119

What are non-modifiable risk factors for coronary atheroma?

Age, male and family history

120

Modifiable risk factors for coronary atheroma?

Hyperlipideamia, smoking, hypertension and diabetes

121

What is Ischeamic Chest Pain?

central, retrosternal/left-sided pain, radiating down left shoulder, arm, neck or jaw

122

What is ischeamic chest pain described as?

heavy, crushing, tightening pain

123

Describe stable angina?

Atheromatous plaques with thin necrotic centre & thick fibrous cap that occlude coronary lumen

Isheamic chest pain on exertion - physically / emotionally

124

At what level of occlusion does angina occur?

>70%

125

Stable angina Tx?

Acute: Sub-lingual nitrate spray
Preventative: B-blockers, Ca channel blockers, oral nitrates, aspirin, statins, ACE inhibitors

126

What is unstable angina?

Progression of the formation of atheromatous plaque with increase occlusion. Thin fibrotic cap and thick necrotic centre.

127

Main characteristic of unstable angina?

ICP at rest - severe pain

128

What is a MI?

Myocardial Infarction - complete occlusion of coronary artery > ischeamic death of myocardium.

129

Cause of MI?

- The thin fibrous cap has ruptured leading exposure of blood to thombogenic necrotic core causing a platelets blot that has occluded the vessel.

- embolism broken off

130

Presentation of MI?

very severe pain, not relived by rest or nitrate spray, breathless, fainting (loss of LV function), feeling of impending doom, sweating, pallor, N/V

131

What is a NSTEMI?

Non-ST elevating MI, infarct not full thickness of myocardium

132

What is a STEMI?

ST elevated MI, infarct = full thickness of myocardium

133

What are the investigations for angina?

Risk factors - corneal Arcus, elevated BP
LV dystfunction
Normal resting ECG (pathological Q wave)
Exercise stress test

134

What is a pathological Q wave indicative of?

Previous MI

135

What is the exercise stress test?

Graded exercise connected to ECG. Increase speed until target HR reached/ chest pain / ECG changes

+ve test = ST depression greater than 1mm

136

What is Acute Coronary Syndrome?

Group of symptoms connected to obstruction of coronary arteries - caused by unstable angina, NSTEMI & STEMI

137

What are the biomarkers in MIs?

Troponin I & T,

Creatine kinase can also be used after 24hours

138

Do you know which ECG lead corresponds to an MI in which coronary artery?

Yes - great!

No - better go learn it!

139

MI Tx?

Anti-thrombotics: aspirin, heparin
Surgery:
Percutaneous Coronary Intervention PCI = angioplasty & stunting

Coronary Artery Bypass Graft (CABG) from radial art or saphenous vein

140

What are causes of acute pericarditis?

Infection - viral, TB
Post-MI
Autoimmune
Ureamia

141

Symptoms of acute pericarditis?

Central/left-sided chest pain
Sharp pain,
worse with inspiration

142

What is Heart Failure?

Heart fails to maintain adequate circulation needed for the body, despite adequate filling pressure

143

Cause of HF?

Hypertension
Dilated cardiomyopathy - alcohol, pre, drugs
Congenital heart defect
Arrhythmia

144

Describe the classes of HF?

1 - asymptomatic

2 - slight limitations in activity, asymptomatic at rest

3 - marked limitations, asymptomatic at rest

4 - inability to do physical activity and symptoms at rest

145

What is congestive heart failure?

Heart failure of both ventricles

Left heart failure > increased pulmonary pressure > right heart failure

146

Signs of Left HF?

Fatigue, SOB, pulmonary oedema

147

Sign of Right HF?

Raised JVP
Peripheral oedema
Ascites
pitting oedema
Fatigue, SOB
Hepatospenomegaly

148

Causes of RHF?

Often 2ndary to LHF
Pulmonary embolism
Pulmonary hypertension
Left--> right shunt

149

HF Tx?

B-blockers,
ACE inhibitors
Nitrates > veno-dilators > reduced BP
Cardiac Glycosides > increase CO & FoC

150

What is shock?

Inadequate distribution of blood to tissues resulting in generalised lack of oxygen to cells.

Either affecting CO or TPR

151

What is cardiogenic shock?

Inability of heart to eject enough blood.

Caused by arrhythmias or ischeamic cardiac damage

152

What is mechanical shock?

Restriction on filling of heart due to cardiac tamponade - pressure on outside of heart, or obstructed blood through lungs - PE

153

What is hypovolameic shock?

Loss of circulating blood volume due to burns / haemorrhage - falling venous pressure = falling CO = falling AP

Tx = IV fluids

154

What is distributive shock?

Uncontrolled fall in TPR due to dramatic fall in AP, Sepsis (circulating bacteria > endotoxin triggering vasodilation) - tachy, red and warm skin- or anaphylaxis (mast cells release histamine causing vasodilation. Tx = adrenaline to trigger A1 receptors --> vasoconstriction) which is associated with bronchoconstriction

155

What types of shock reduce CO?

Hypovoleamic, mechanical or cardiogenic shock

156

What type of shock leads to reduced TPR?

Septic or anaphylactic shock

157

What are the effects of HF in the body?

- Activation of RAAS due to underperfusion of kidneys > reduced GFR> activates cells to release renin > Angiotensin 2 > vasoconstriction & Aldosterone > Na & Water retention > increased blood volume

- ADH release > increased water uptake