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1

List the transportation roles of the heart and circulation

Transporting:

  • Vitamins
  • Nutrients
  • Oxygen/CO2
  • Hormones
  • Immunoglobulins
  • RBC/WBCs

2

Give the thermoregulatory roles of the heart and circulation

  • Counter-current exchange mechanism
  • Circulation of the skin

3

Give the 3 major parts of the circulation

  • Heart
  • Systemic circulation
  • Lung circulation

4

Describe Starling's effect

To increase load, the heart automatically reacts with extra work

without hormonal/neuronal factors

5

Describe the heart's work load status during rest

The heart is working in the lower range of its total working capacities

This is ensured by parasympathetic predominance

6

A decrease of parasympathetic activity may cause...

An increase in the mechanical performance of the heart

7

The autonomity of the heart rythmn is due to...

Rythmn generators in the SA node

8

Give the main parameter of cardiac mechanical performance

Cardiac output

The volume of blood propelled into the aorta from the left ventricle per unit time

9

List the layers of the heart

  • Endocardium
  • Myocardium
  • Epicardium
  • Pericardium

10

Give the contractile components of the myocardium

  • Heart muscle fibres (working fibres)
    • Stretching enhances their force-generating capability

11

Give the non-contractile components of the myocardium

  • Serially attached elastic elements (SEC)
  • Parallelly attached elastic elements (PEC)
  • Collagen

12

List the functions of the pericardium

  • Fixation: keeps the heart in the mediastinum
  • Protection from infection from other organs
  • Prevents excessive dilation of the heart during hypervolemia
  • Lubricates the heart

13

Describe fetal circulation in relation to the pulmonary circulation

  • Lungs not functioning
    • Blood bypasses lungs foramen ovale
    • Between L & R atrium

14

Describe the closing of foramen ovale 

  1. Pressure in left atrium increases
  2. Flap valve covers foramen ovale
  3. After 1 year, the foramen completely closes
  4. It is then regarded as fossa ovalis

15

  • What percentage of the population does the foramen ovale not seal?
  • What is the condition called?

  • 30%
  • Patent foramen ovale (PFO)

16

 Name the fetal vessel between a. aorta thoracica and a. pulmonalis

Ductus botallo

17

When does ductus botallo close?

4 weeks postpartum

18

List the excitable varieties of cardiac tissue

  • Pacemakers
  • Conductive system
  • Working fibres

19

Purpose of the Aschoff-Tawara (AV) node

Delays the atrial signal

So atrial contraction precedes the ventricular contraction

20

Resting membrane potential (RMP)

Diastole:

  • -90mV
  • Spontaneous depolarisation followed by AP
  • RMP doesn't exist in pacemaker cells

 

21

Describe action potential (AP)

  1. Stimulation
  2. Ion channels of membrane open
  3. Ion exchange between the two sides
  4. Action potential

22

Pacemaker potentials

23

Pacemaker cells

  • Located: SA / AV node
  • Allow continuous generation of excitation
  • No RMP
  • Repolarisation: Transmembrane potential -55mV
  • Automatic depolarisation follows

24

This electrical activity is expressed in...

Sinoatrial (SA) node

25

This electrical activity is expressed in...

Ventricular muscle

26

Pacemaker action potential is...

  • Slower/faster

and

  • Lower/higher

...than cardiomyocytes

  • Slower
  • Lower

27

Round pacemaker cells

Sites of the generation of excitation

28

Elongated/slender cells

Conduct/synchronise excitation generated in round pacemaker cells

29

Maximal depolarisation potential (MDP)

No RMP developed after the previous AP reaches -55mV

30

  • K+ channels close
  • Na+ channels open

31

  • Ca2+ channels open
  • Nachannels close

32

This electrical pattern is representative of...

Pacemaker cells

33

  • Ca2+ channels close
  • Kchannels open

34

  • Kchannels close
  • Nachannels open

35

Overshoot

36

+15 mV

37

MDP

38

SDD

39

Threshold potential

40

Maximal diastolic potential; virtual resting potential (MDP)

  • Slow Nachannels open spontaneously
  • Slow depolarisation begins

41

Spontaneous diastolic depolarisation

No RMP until threshold potential

42

'Overshoot'

  • Ca2+ influx and only slow Nachannels
  • +5/+15mV (Lower than working fibres)

43

Repolarisation

  • Kefflux until MDP

44

What does Ih (hyperpolarisation activated) channel opening trigger?

If Threshold of -40mV is reached, the following will open:

  • Type-T, rianodin sensitive calcium channel
  • Type-L DHP sensitive calcium channel

45

The opening of Type-T and Type-L channels causes...

  • Calcium to flow from the EC into the cell
  • Causes a transient Ca-influx

46

The period from MDP to threshold potential is known as...

Spontaneous diastolic depolarisation (SDD)

47

Depolarisation of the SA node is due to which channels?

Long-lasting Ca2+ channels

48

Why is the membrane potential of the '0' phase so steep?

  • There are no fast Na+ channels in the membrane of the round cells
  • Only long lasting Ca-channels determine this phase

49

What occurs from the point of potassium channels opening?

  • Efflux of Kions from cell
  • Repolarisation until MDP is reached
  • Activation of Ih channels starts a new cycle

50

Term given to the frequency of contraction

Chronotrop

51

Term given to the speed of conduction

Dromotrop

52

Term given to the threshold of contraction

Bathmotrop

53

Term given to the force of contraction

Inotrop

54

Vagus escape

  • Stimulation of n. vagus 
  • Effectiveness of further stimulation disappears
  • Switch from nomotop → heterotop excitation
  • AV node now generates rythmn, not SA node

55

Which nerve controls heart rate?

N. vagus

56

Describe the stimulation of SA node round cells

Sympathetic effect

  • Stimulation of B1-receptor
  • Same effect triggered by norepinephrine and epinephrine
  • Parasympathetic suppression, enhancing the effect

57

Describe how stimulation of B1-Rec can cause sympathetic effect

  1. Stimulation of G-protein mediated IC cAMP increase
  2. Na+ & K+ channels open
  3. MDP shifts upward, steepness of SDD increases
  4. Threshold reduced
  5. Heart rate increase

58

Describe parasympathetic effects altering heart rate

  1. Acetylcholine stimulates muscarinic acetylcholine receptors on round cells
    1. cAMP decreases
    2. MDP shifted down
    3. SDD slope decreases
    4. Threshold potential elevates
    5. Hyperpolarisation
  2. Heart rate decreases

59

Describe the metabotropic effect on heart rate

  1. Acetylcholine opens metabotropic K+ channels
  2. Further hyperpolarisation
  3. Decreased frequency

60

Heart conduction in small animals

  • Subendocardial conduction
  • Conducting fibres don't penetrate working muscle deeply

61

Heart conduction in large animals

  • Subepicardial conduction
  • Fibres pass deeply into the ventricle

62

Bachmann's bundle

63

Left posterior bundle

64

Signal arriving from the SA node

Nomotop excitation

65

A signal arriving from AV node

Heterotop excitation

66

Anulus fibrosus

  • Represents electric resistance
  • Synchronises atrioventric cooperation

67

How long is the indicated period?

~200 ms

68

What is shown?

Action potential of a working fibre

69

Resting Membrane Potential

-90 mV

70

Depolarisation

  • Nainflux

71

Overshoot

+25 mV

72

Rapid repolarisation

  • Kefflux (early)
  • Cl- influx

73

Plateau

  • Ca2+ influx
  • Kefflux (slow)

74

Rapid repolarisation

  • Kefflux (late)

75

Late hyperpolarisation

  • Kefflux (late)

76

What is the purpose of the plateau phase?

Blocks premature AP generation/contraction

77

Ion flow of working fibres during action potential 

  1. Depolarisation
  2. Rapid repolarisation
  3. Plateau
  4. Rapid repolarisation
  5. Later hyperpolarisation

78

The flow of charges across the membrane is dependent on...

  • Permeability
  • Electrochemical gradient

79

Metabotropic channels

  • Under the control of hormones + neurotransmitters
  • Conductance properties of these channels altered
    • Change in heart function

80

Which channels are responsible for action potential?

Voltage-dependent Nachannels

81

Which channels open in each phase of the AP?

Phase 1: Early potassium channels

Phase 2: Slow potassium channels

Phase 3: Late potassium channels

82

The effect of the overshoot

  • Activation of calcium channels
  • Calcium ions enter the cell
  • Repolarisation is elongated

 

83

The duration of the plateau phase is:

  • Longer closer to the...
  • Shorter closer to the...

Longer closer to the endocardium

Shorter in the epicardium

84

Absolute refractory phase (ARP)

  • AP cannot be initiated

85

Relative refractory phase (RRP)

  • Strong stimulus may initiate AP

86

Supernormal phase (Refractory phase)

  • A slight stimulus may initiate AP
  • AP will be submaximal

87

Absolute refractory phase

  • No stimulus
  • A new action potential is elicited before the plateau

88

Relative refractory phase

  • A stimulus is given after the plateau
  • Before reaching threshold potential
  • Can cause a new AP if strong enough

89

Supernormal phase

  • Between threshold and RMP
  • Slight stimulus: Gives new AP
    • Premature new contraction
    • Can be fatal in the ventricle (fibrillation)

90

Atrial fibrillation

  • Electric stimulation of the atrium (repeated contractions)
  • Ventricle maintains normal circulatory pressure
  • Non-fatal

91

Ventricular fibrillation

  • Normal blood pressure cannot be maintained
    • May drop to '0'
  • Systole and diastole disappears (Fatal)

92

Defibrillation

Strong electric current:

  • Desynchronisation stops
  • SA node synchronised again
  • Normal rhythm
  • Nomotop excitation returns

93

Difference between AP and mechanogram of cardiac muscle

Mechanogram is almost parallel to AP

94

Difference between AP and mechanogram of skeletal muscle

  • No plateau phase
  • AP lasts for 1 millisec, compared with 200 millisec of heart
  • Mechanogram develops only after AP has vanished

95

Electromechanical coupling

Connection between electric stimulus and mechanical signal

96

Which process is shown?

Electromechanical coupling

97

1

AP spreads onto the cell

98

2

  • AP reaches T-tubules
  • Activates L-type Ca2+ channels

99

3

  • Conformational changes of L-type channels
  • → T-type channels on SR open

100

4

  • Elevating the sarcoplasmic level of Ca2+ 
  • → Opens Ca2+ dependent channels on SR

101

5

  • Elevating sarcoplasmic Ca2+ level
  • Opens Ca2+  dependent channels on cell membrane

102

6

  • A huge amount of intracytoplasmic Ca2+ around the sarcomeres
  • Contraction

103

Which process is shown?

Elimination of calcium signal

104

1

After contraction

Na+/Ca2+ antiporter into extracellular space

105

2

ATP-dependent Ca2+ transporter into SR

  • IC Ca2+ conc. decreases
  • Relaxation

106

What is the structural unit of electromechanical coupling?

Diad

T-tubules and SR are in contact here

107

Steps of action potential

  1. L-type Ca2+ channels open (Voltage-gated)
  2. Rianoid Ca2+ channels open
  3. Elevated Ca2+ in the cytoplasm →
  4. Causes Ca2+ dependent channels to open
  5. Intracytoplasmic Ca2+ around sarcomeres increases
  6. Contraction

108

Describe the ion movement during/after contraction

  1. ATP-dependent Ca2+ pump drives Ca2+ back into the SR
  2. Na+/Ca2+ antiport pumps Ca2+ back to the EC space
  3. IC Ca2+ conc. drops
  4. Relaxation

109

What is expressed in the figure?

Einthoven's triangle

  • Einthoven 1: Right Arm ⇔ Left Arm
  • Einthoven 2: Right Arm ⇔ Left Leg
  • Einthoven 3: Left arm ⇔ Left Leg

110

Einthoven's bipolar leads detect...

Changes in the dipole, projected onto the body surface

111

ECG measures...

The sum of the electrical activity of single myocytes

112

An ECG is a sum of...

An EAG and an EVG

113

Name the trace

EAG

114

Name the trace

EVG

115

Name the trace

ECG

116

How long is this period?

0.5-0.10 sec

117

How long is this period?

0.12-0.20 sec

118

0.06-0.10 sec

119

P-wave

  • Upward deflection
  • Atrial depolarisation begins
  • SA node already depolarised (undetectable)

120

PQ-segment

  • On isoelectric line
  • Total atrial depolarisation
  • AV conduction

121

QRS-complex

  • The beginning of ventricular depolarisation
  • Repolarisation of atrium

122

Q-wave

  • Downward deflection
  • Stimulus runs through Bundles of His, through the septum, toward the basis of the heart

123

R-wave

  • Max ventricular depolarisation
  • Stimulus runs from endocardium to pericardium
  • From the base to the apex
  • Total ventricular mass depolarises

124

S-wave

  • Depolarisation of the right ventricle

125

ST-segment

  • Isoelectric line on the oscilloscope
  • Ventricles totally depolarised

126

T-wave

  • Ventricular repolarisation
  • Upwards deflection → Man + Small animal
  • Downward deflection → Other species

127

TP-segment

  • Resting phase
  • The oscilloscope is at isoelectric line
  • Myocytes are positive outside, negative inside

128

ECG is used in the diagnosis of...

  • Pathologic electrical events
  • Problems of conducting system
  • Anatomical disturbances

129

What are the types of ECG?

  • Unipolar ECG
  • His bundle ECG
  • Oesophagal ECG
  • Vectorcardiography

130

Unipolar ECG

  • RA, LA, LL connected to each other
  • Via 0 potential reference point
  • PD between the reference point and the different points measured

131

His bundle ECG

  • An electrode placed up to the septum
  • Through a vein catheter

132

Oesophageal ECG

An electrode placed through oesophagus close to the heart

SA, AV nodes + conduction system analysed

133

Vector loop

  • Provides information on heart function of territories
  • The connection of vectors from the R wave

134

Vectorcardiography

  • Anatomical information of the heart
  • Forms the 'electrical axis of the heart'
  • Peak values of R-leads: produces a vector

135

Echocardiography

  • Ultrasound examination
  • A detailed picture of the cardiac anatomy and blood flow

 

136

Which fibres passively support the filling of the heart?

Serially and Parallelly attached elastic fibres

(SEC/PEC)

137

Give the function of the elastic elements of myocardium

  • Passive store of energy while stretched
  • Can be utilised as surplus energy for the next contraction

138

When is SEC stretched?

Systole

139

When is PEC stretched?

During diastole

140

What is the function of collagen in the myocardium?

  • Prevention of overexpansion and rupture
  • Resistant during the maximal filling of the heart

141

Cardiac muscle

  • Striated → sarcomeres
  • Shorter than skeletal muscle
  • More mitochondria
  • Less extensive SR
  • Often binucleate and polyploid
  • Continued division after actin/myosin synthesis

142

What are the types of heart contraction?

  • Isotonic
  • Isometric
  • Auxotonic
  • Preload
  • Afterload

143

Isometric contraction

  • 1st phase
  • Weight stretches SEC elements only
  • Weight doesn't move yet
  • Stretch present, but no shortening

144

Isotonic contraction

  • 2nd phase
  • Stretch with SEC increases
  • Weight begins to move
  • Shortening occurs
  • Stretching force remains

145

What is expressed in the figure?

The normal working range of a single working fibre

  • Cardiac muscle shows max tension only at an increased sarcomere length

146

Skeletal muscle (Optimum sarcomeric length)

  • Cross bridges in the right place
  • All Ca2+ binding sites saturated

147

Cardiac muscle (optimal sarcomeric length)

  • All bridges in correct place
  • Not enough Ca2+
  • Therefore, only a few binding sites are saturated

148

Cardiac muscle (Upper-edge of optimal sarcomeric length)

  • Cross bridges in the right place
  • Ca2+ binding sites are saturated
  • This is due to the increased length

149

The degree of contraction of cardiac muscles is dependent on...

The length of sarcomeres

150

Compare skeletal and cardiac muscle: At very short sarcomeric lengths

  • Both perform less
  • Optimum actin/myosin constellation is distorted

151

Compare skeletal and cardiac muscle: At very large sarcomeric lengths

  • Performance is small in both
  • Few/no myosin heads have actin binding sites

152

Compare skeletal and cardiac muscle: between 1.9-2.5 sarcomeric lengths

  • An optimal opposition to binding sites and myosin heads occurs
  • Cardiac muscle: Maximal performance requires pre-stretch

153

Give the 'law of the heart' (Starling)

  • Increased stretch results in increased contraction
  • Irrespective to the innervation of the heart
  • (Like a sling-shot)

154

EDV

End-diastolic volume

At the end of diastole, ventricles are maximally filled

155

ESV

End-systolic volume

When ventricles are maximally emptied, there is still some blood remaining in them

156

SV

Stroke Volume

  • Volume passing through the aorta in each cycle
  • EDV-ESV

157

The formula for Cardiac output

(EDV-ESV) x Freq. = CO = SV x Freq.

158

What is shown?

Starling's heart-lung preparation

159

Describe starling's heart-lung preparation

  • Heart can adapt to increased load due to mechanical reasons
  • Also observed in an isolated heart (No nerves/hormones)
  • Arterial side represented by peripheral resistance
  • Venous side represented by a reservoir

160

What was involved in Starling's two experiments?

Experiment 1: Increasing venous return

Experiment 2: Increasing peripheral resistance

Volume fractions were measured for both

161

Describe the effects of increasing venous return

  • Immediate EDV increase
  • Delayed ESV increase
  • SV + CO increase

Increased load generates increased contraction

162

Describe the effects of increased peripheral resistance

  • Immediate increase in residual volume (ESV↑; SV↓)
  • Delayed ESV and EDV increase proportionally
  • SV increases to the same level

SV and CO will be set as it was before

163

Describe the effects of lying down on the circulation

  1. More blood enters ventricle
  2. Dilation
  3. Increased performance

164

Heteromeric autoregulation

  1. Increased blood leaving the right compartment
  2. Dilation and stretching of the left side
  3. Starling mechanism activated
  4. Automatic compensation between left and right compartments

165

Heterometry

Small differences occurring in the volume of blood appearing the left and right sides of the heart

166

Blood volume passing through the left and right side of the heart should be...

The same

167

Heterometry can be adjusted by...

Starling effectt

168

Which two ways can CO be measured?

  • Fick's principle
  • Stewart's principle

169

Fick's principle

More widely used method

CO:

  • O2 taken up by the lung per unit time = O2 taken up by tissues
  • CO = Total Ouptake / arterio-venous Odifference

 

170

Stewart's principle

  • Inject IV Evans-blue
  • Sample collection + analysis
  • Plot curve and extrapolation
  • Area under the extrapolated cure = CO

171

Ventricular compliance

Dilating capacity

 

172

Ventricular compliance is an important parameter for assessing...

Adaptability of the heart

(Dilating ability of ventricles)

173

Value of EDV ventricular pressure

5 mmHg

174

EDV ventricular pressure can be extrapolated to give an EDV value of...

60ml

175

Describe the increase of EDVP

  • Proportional increase of EDV(+SV)
  • Until 25 mmHg
  • (collagen fibres prevent further dilation)

176

Describe ventricular compliance in elderly animals

  • Compliance curve is shifted to the right
  • Two-fold EDVP is needed to achieve the normal EDV level

177

Describe the cause of ventricular compliance in elderly animals

  • Increased rigidity of elastic fibre
  • Aging of muscle cells

178

The formula for total work of the heart

W= Wouter + Winner

Wouter = Mechanical

Winner = Heat production

179

Wouter =

SV x ΔP

ΔP = (arterial average pressure)

180

Burning 1L oxygen produces...

20kJ energy

181

Give the efficiency of the heart

10-20% efficiency

182

Kinetic component of outer mechanical work amounts for...% of total work

4%

183

The formula to calculate the performance of the heart

P = Work/time = CO

184

What does the Rushmer diagram analyse

  • Analyses outer/mechanical work of the heart
  • as a function of volume and pressure of LV

185

Rushmer Diagram

186

  • Mitral Valves close
  • Isovolumetric contraction

187

  • Aortic valves open
  • Ejection phase

188

  • Semilunar valves close
  • Isovolumetric relaxation

189

  • Mitral valves open
  • Filling

190

Law of Laplace in a pathological context

Increased ventricular volume → increased oxygen consumption →  Reduced cardiac efficiency

Wall tension maintained only by increased O2 consumption

191

Increased ventricular volume causes...

An increase in the energy required by the heart muscle

192

Law of Laplace

Constant pressure (P)

within a sphere of increasing radius (r)

can only be maintained by an increase in wall tension (T)

193

Factors influencing cardiac output can be investigated by analysing...

The formula used for calculating CO

194

Factors of EDV affecting cardiac output

  • Ventricular filling time
  • Ventricular compliance
  • Central venous pressure

195

Factors of ESV affecting cardiac output

  • Arterial pressure
  • Contractility
    • Increases by sympathetic
    • Decreases by sympathetic

196

Factors of frequency affecting cardiac output

  • Sympathetic effects
  • Parasympathetic effect

197

Contractility

The performance of the heart at a given preload and afterload

198

Contractility is characterised by...

  • Isometric tension
  • The speed of contraction

199

Clinically, what is the best estimate of contractility?

Ejection fraction

200

Give the sympathetic effects of CO frequency

  • Artificial increase
    • Duration of diastole 
    • therefore CO decreased
  • Natural increase
    1. Reduced systolic time
    2. Reduced diastolic time
    3. CO increases

201

Which system controls the:

  • Chronotrop
  • Dromotrop
  • Bathmotrop
  • Inotrop

Sympathetic nervous system

202

An increase in heart rate does not guarantee an increase in...

Cardiac output

203

Why doesn't CO increase with artificial heart rate increase?

  • The heart rate increased at the expense of diastole
  • The dilation of ventricles, therefore, doesn't increase
  • SV therefore increased

204

Sympathetic stimulation increases...

  • Heart rate
  • Velocity of contraction
  • Maximal isometric contraction force

205

Why does natural heart rate increase cause larger cardiac output?

  1. Sympathetic stimulation
  2. The velocity of contraction increases
  3. Duration of systole decreases
  4. Stroke volume maintained
  5. CO increases

206

What occurs because systole and diastole don't separate fully in time?

  • A fraction of blood can enter the ventricles
  • During ventricular diastole

207

Prior to systole, which muscular motions occur in the heart?

  • Twisting of the heart
  • Shift of the heart towards the base and back to the apex

208

Diastole

209

Isovolumetric contraction

210

Auxotonic contraction

211

Fast ejection

212

Slow ejection

213

Isovolumetric relaxation

214

Fast filling

215

Isotonic relaxation

216

Reduced filling

217

Atrial systole

218

Aortic pressure

219

Atrial pressure

220

Ventricular pressure

221

Ventricular volume

222

ECG

223

Heart sounds

224

Analysis of ECG and pressure values can show...

  • Bloodflow of the heart
  • Role of the valves

225

Atrial contraction

Phase 1

  • Begins after P-wave
  • Pressure increase in lumen
  • Blood passes into ventricles through cuspidal valves
  • Ventrical muscles relaxed
  • Aortic BP decreases

226

Isovolumetric phase

Phase 2

  • Begins with QRS complex
  • Increased ventricular wall tension
  • Increased pressure
  • AV valves closed
  • Ventricular pressure increases until aortic pressure is reached

227

Rapid ejection

Phase 3

  • Semilunar valves open
  • Cuspidal valves closed
  • Blood passes into aorta + pulmonary trunk
  • Increased aortic pressure

228

Reduced ejection

Phase 4

  • Semilunar valves open
  • Cuspidal valves remain open
  • Blood passes into aorta + pulmonary trunk

  • Increased aortic pressure

229

Isovolumetric relaxation

Phase 5

  • All valves are closed
  • No blood flow

230

Rapid filling

Phase 6

  • Semilunar valves closed
  • Cuspidal valves open
  • Low ventricular pressure
  • Ventrical filling
  • Major volume of blood flows into ventricles in this phase

231

Reduced filling

Phase 7

  • Cuspidal valves open
  • Semilunar valves closed
  • Ventricular muscles cells relaxed
  • Passive flow into ventricles
  • Aortic pressure drops

232

What generates heart sounds?

The closing of valves

233

Ist heart sounds

Systolic - closure of cuspid valves

  1. The vibration of contracted muscle
  2. Turbulence due to cuspid closure
  3. Turbulence due to fast ejection

234

IInd heart sounds

Diastolic - Closure of semilunar valves

  1. Aoric valve closes
  2. Pulmonary valve closes
  3. Intrathoracic pressure drops
  4. Delayed closure of pulmonary semilunar valves

235

3rd heart sounds

Arabic label

Rapid filling of ventricle

236

4th heart sounds

  • Turbulent flow
  • Caused by atrial contraction

237

Murmurs are caused by...

Stenosis

(distorted heart sounds)

238

Ejection fraction

Volumetric fraction of fluid ejected from a chamber with each contraction