Cardiorespiratory Flashcards Preview

1 - FINALS > Cardiorespiratory > Flashcards

Flashcards in Cardiorespiratory Deck (275):
1

Tunica intima structure

Endothelium layer
Loose CT
Internal elastic lamina

2

Tunica intima structure

Endothelium layer
Loose CT
Internal elastic lamina

3

Tunica media structure

Circularly arranged smooth muscle
Supporting ECM with collagen and elastic fibres
External elastic lamina

4

Tunica adventitia

Loose CT
Vaso vasorum

5

Endocardium structure

Inner endothelium lining
Supporting highly elastic fibrocollagenous CT

6

Myocardium structure

Cardiac myocytes linked by intercalated discs
Supporting fibrocollagenous CT

7

Epicardium structure

Outer fibrocollagenous tissue
Large amounts of adipose tissue
Outer mesothelium - visceral pericardium

8

Elastic arteries

Predominance of elastin and little smooth muscle in tunica media
Found in large arteries just downstream of the heart
Function to smooth out large pressure fluctuations

9

Muscular arteries

Medium to small sized arteries
Have the basic arterial structure

10

Which types of cells form foam cells

Macrophages and smooth muscle cells

11

What does the fibrous cap consist of?

Smooth muscle cells with an ECM with dense collagen, elastic fibres and proteoglycans

12

Upper respiratory tract

Mouth --> larynx

13

Lower respiratory tract

Trachea --> terminal bronchioles

14

Classic respiratory epithelium

Pseudostratified columnar, ciliated epithelium with mucous secreting goblet cells

15

How does the epithelium change throughout the lungs?

Gradual transition from pseudostratified to columnar to cuboidal epithelium
Gradual decrease in number of goblet cells

16

Epithelium in the pharynx

Stratified squamous

17

Immune properties of the respiratory tract

Mucociliary escalator
MALT

18

Trachea layers

Respiratory epithelium
Lamina propria - with elastin and lymphoid tissue
Submucosa - with many glands
C shaped rings of hyaline cartilage
Adventita

19

Bronchi structure

Shorter epithelial cells
Lamina propria contains more elastic tissue
Muscularis mucosae begins to form
Fewer submucosal glands
Cartilage in plates rather than rings

20

Tertiary bronchi structure

Simple columnar epithelium
Prominent muscularis mucosae
Few cartilage plates
Few mucous glands

21

Bronchiole structure

Ciliated columnar epitehlium
Few goblet cells
Clara cells
Prominent muscularis mucosae
No cartilage
No mucous glands

22

Respiratory bronchiole structure

Occasional alveoli in their walls
Ciliated cuboidal epithelium
Smooth muscle in their walls

23

Alveolar cell types

Type I pneumocyte - simple squamous lining cell
Type II pneumocyte - cuboidal cells that produce surfactant
Pulmonary macrophages - immune surveillance

24

Blood-air barrier

Type I pneumocyte
Basement membrane
Capillary endothelium

25

Functions of platelet factors

Promote aggregation with other platelets
Alter local blood flow
Initiate coagulation cascade
Encourage vascular repair

26

Neutrophils

60-70% of blood WBCs
First line of defence against pathogens
Highly phagocytic
Role in inflammation

27

Eosinophils

1-4% of blood WBCs
Defence against parasites and helminths
Increased levels in allergic responses

28

Basophils

29

Monocytes

2-6% of blood WBCs
Mature into macrophages when they enter the tissues
Main roles in phagocytosis, antigen presentation and cytokine production

30

Lymphocytes

20-40% of blood WBCs
B cells and T cells
Can form memory cells - longest WBC lifespan

31

CCBs

Amlodipine, dilatiazem
Blocks calcium entry into smooth muscle cells
Vasodilators and reduce heart rate and contractility
May worsen heart failure

32

CCBs

Amlodipine

33

Tunica media structure

Circularly arranged smooth muscle
Supporting ECM with collagen and elastic fibres
External elastic lamina

34

Tunica adventitia

Loose CT
Vaso vasorum

35

Endocardium structure

Inner endothelium lining
Supporting highly elastic fibrocollagenous CT

36

Myocardium structure

Cardiac myocytes linked by intercalated discs
Supporting fibrocollagenous CT

37

Epicardium structure

Outer fibrocollagenous tissue
Large amounts of adipose tissue
Outer mesothelium - visceral pericardium

38

Elastic arteries

Predominance of elastin and little smooth muscle in tunica media
Found in large arteries just downstream of the heart
Function to smooth out large pressure fluctuations

39

Muscular arteries

Medium to small sized arteries
Have the basic arterial structure

40

Which types of cells form foam cells

Macrophages and smooth muscle cells

41

What does the fibrous cap consist of?

Smooth muscle cells with an ECM with dense collagen, elastic fibres and proteoglycans

42

Upper respiratory tract

Mouth --> larynx

43

Lower respiratory tract

Trachea --> terminal bronchioles

44

Classic respiratory epithelium

Pseudostratified columnar, ciliated epithelium with mucous secreting goblet cells

45

How does the epithelium change throughout the lungs?

Gradual transition from pseudostratified to columnar to cuboidal epithelium
Gradual decrease in number of goblet cells

46

Epithelium in the pharynx

Stratified squamous

47

Immune properties of the respiratory tract

Mucociliary escalator
MALT

48

Trachea layers

Respiratory epithelium
Lamina propria - with elastin and lymphoid tissue
Submucosa - with many glands
C shaped rings of hyaline cartilage
Adventita

49

Bronchi structure

Shorter epithelial cells
Lamina propria contains more elastic tissue
Muscularis mucosae begins to form
Fewer submucosal glands
Cartilage in plates rather than rings

50

Tertiary bronchi structure

Simple columnar epithelium
Prominent muscularis mucosae
Few cartilage plates
Few mucous glands

51

Bronchiole structure

Ciliated columnar epitehlium
Few goblet cells
Clara cells
Prominent muscularis mucosae
No cartilage
No mucous glands

52

Respiratory bronchiole structure

Occasional alveoli in their walls
Ciliated cuboidal epithelium
Smooth muscle in their walls

53

Alveolar cell types

Type I pneumocyte - simple squamous lining cell
Type II pneumocyte - cuboidal cells that produce surfactant
Pulmonary macrophages - immune surveillance

54

Blood-air barrier

Type I pneumocyte
Basement membrane
Capillary endothelium

55

Functions of platelet factors

Promote aggregation with other platelets
Alter local blood flow
Initiate coagulation cascade
Encourage vascular repair

56

Neutrophils

60-70% of blood WBCs
First line of defence against pathogens
Highly phagocytic
Role in inflammation

57

Eosinophils

1-4% of blood WBCs
Defence against parasites and helminths
Increased levels in allergic responses

58

Basophils

59

Monocytes

2-6% of blood WBCs
Mature into macrophages when they enter the tissues
Main roles in phagocytosis, antigen presentation and cytokine production

60

Lymphocytes

20-40% of blood WBCs
B cells and T cells
Can form memory cells - longest WBC lifespan

61

ACEIs

Ramipril, captopril
Lower blood pressure
Used after MIs in diabetics
Side effects = K+ retention, cough

62

CCBs

Amlodipine

63

Thiazide diuretic

Bendoflumethiazide

64

Loop diuretic

Furosemide

65

Beta blockers

Propanolol, atenolol
Reduce sympathetic tone
Used in heart failure and after MI

66

Aldosterone blockers

Spironolactone
Used in heart failure

67

Angiotensin II receptor antagonists

Losartan

68

Digoxin mechanism of action

Inhibits Na/K ATPase in cardiac myocytes
Myocyte Na+ rises
Increased IC calcium
Improved contractility
Slows heart rate at AV node

69

Hypertension treatments

ACEI, CCBs, diuretics

70

Heart failure treatments

Reduce preload and afterload
Diuretics
ACEIs
Beta blockers
Digoxin

71

Angina treatments

Nitrates
Beta blockers
CCBs

72

Short term beta2 agonist

Salbutamol
Receptor activates adenylyl cyclase
ATP --> cAMP
Lowers IC calcium
Relaxes smooth muscle

73

Long term beta2 agonist

Salmeterol, formoterol

74

Anti-muscarinic

Ipratropium = short term
Tiotropium = long term
Mainly act on M3 receptors

75

Superior mediastinum contents

Thymus
Large veins
Large arteries
Trachea
Oesophagus
Thoracic duct
Sympathetic trunks

76

Path of the right vagus nerve

Enters lateral to the right common carotid and passes Anterior to the subclavian artery
Here it gives of the right recurrent laryngeal
Passes posterior to subclavian vein and SVC
Joins course of oesopahgus

77

Path of left vagus nerve

Enters lateral to the left common carotid
Anterior to the subclavian artery and posterior to brachiocephalic vein
Passes over the aortic arch and gives off left recurrent laryngeal
Passes posterior to the lung root and gives off branches to the pulmonary and cardiac plexuses

78

How do the phrenic nerves enter the mediastinum?

Between the subclavian artery and vein

79

Where does the right phrenic nerve travel?

Over pericardium and right atrium
Anterior to the lung root

80

Where does the left phrenic nerve travel

Over the aortic arch and left atrium and ventricle
Anterior to the lung root

81

Trachea length and spinal levels it extends from and to

13cm
C6--> T4

82

Where does the thoracic duct cross the midline?

T4/5

83

Azygous vs hemiazygous

Azygous drains right side
Hemiazygous drains left side

84

Where does the hemiazygous vein cross and empty into the azygous vein?

T7-8

85

Where does the azygous vein empty into?

SVC just before it enters the right atrium

86

Left coronary arteries

LAD
Circumflex
Left marginal

87

Right coronary arteries

Right marginal
Posterior descending

88

Where does the great cardiac vein run?

Anterior IV sulcus

89

Where does the middle cardiac vein run?

Posterior IV sulcus

90

Where does the small cardiac vein run?

With the right marginal artery

91

What divides the pectinate and smooth muscle of the atria?

Cristae terminalis

92

Where is the moderator band found?

Right ventricle

93

What happens when the papillary muscles contract/

Chordae tendinae pulled taut
Valve cusps close

94

Blood supply to thoracic wall

Anterior intercostals from internal thoracic artery
Posterior intercostals from thoracic aorta

95

Venous drainage of thoracic wall

Anterior intercostals drain into the internal thoracic vein
Posterior intercostals drain to the azygous and hemiazygous veins

96

Where is the intercostal bundle found?

Inferior to the superior rib
Between innermost and internal intercostals

97

External intercostal fibre direction

Inferomedially

98

Internal and innermost intercostal fibre direction

Inferolaterally

99

What passes through the diaphragm at T8?

Interior vena cava

100

What passes through the diaphragm at T10?

Oesophagus
Vagus nerve

101

What passes through the diaphragm at T12?

Aorta
Azygous vein
Thoracic duct

102

Site of referred pain from mediastinal and diaphragmatic parietal pleura

Neck and shoulders
C3,4,5

103

What forms the nasal septum?

Ethmoid bone
Vomer
Hyaline nasal cartilage

104

What forms the floor of the nasal cavity?

Palatine process of maxilla
Horizontal process of palatine bone

105

Paranasal sinus functions

Decrease weight of skull
Increase vocal resonance
Humidifying air
Regulation of gas pressure
Immunological defence

106

Intrinsic laryngeal muscles

Cricothyroid
Crico-arytenoids
Vocalis

107

Membranes of the larynx

Cricothyroid membrane
Vocal fold
Vestibular fold
Thyrohyoid membrane

108

Internal laryngeal nerve

Sensory to the larynx above the vocal fold

109

External laryngeal

Motor to cricothyroid to provide tone to the voice

110

Recurrent laryngeal

Sensory to larynx below the vocal fold
Motor to all muscles of the larynx except the cricothyroid

111

Larynx blood supply

Superior and inferior thyroid arteries from ECA
Drainage from thyroid veins to IJV

112

Organisation of the lung hilum

Bronchi lie posteriorly
Pulmonary arteries lie superior
Pulmonary veins lie below and infront

113

Where do inhaled foreign objects often lodge?

Right main bronchus - straighter course

114

Which X-ray angle gives cardiac enlargement?

AP

115

Which heart chamber has more pectinate muscle?

Right
In left only in the auricle

116

What are trabeculae carnae?

Ridges of muscle projecting out from the ventricle walls

117

What empties into the right atrium

SVC
IVC
Coronary sinus

118

Muscles of quiet inspiration

Diaphragm
External intercostals
Interchondral part of internal intercostals

119

Accessory muscles of inspiration

Scalenes
SCM
Pec major

120

Muscles of forced expiration

Interosseous part of internal intercostals
Abdominal muscles
Serratus posterior inferior

121

External carotid artery branches

Superior thyroid
Ascending pharyngeal
Lingual
Facial
Occipital
Posterior auricular
Superficial temporal
Maxillary

122

Where do thyrocervical arteries come from?

Subclavian artery

123

Pharyngeal arches

Palatoglossus anteriorly
Palatopharyngeal posteriorly

124

What divides the superior and inferior mediastinum?

Sternal angle

125

Where do the humeral circumflex arteries branch from?

Axillary artery

126

Which artery gives off the common interosseous artery?

Ulnar artery

127

What drains into the superior meatus?

Posterior ethmoid sinuses

128

What drains into the middle meatus?

Frontal, maxillary and anterior ethmoid sinuses

129

What drains into the inferior meatus?

Nasolacrimal duct
Auditory (eustachian) tube - at the posterior aspect

130

Central chemoreceptors

Specialised neurones on the surface of the ventral medulla that are sensitive to the pH of the CSF

131

What is the action of carbonic anhydrase?

Convert carbonic acid into bicarbonate and protons

132

What happens when the acidity of CSF is increased?

Increases stimulation of central chemoreceptors
Stimulates neurones in the respiratory centre in the medulla
Drives increased ventilation to expel more CO2 from the lungs so reduce pH

133

Normal pH of CSF

7.32-33

134

Lung based mechanoreceptors

Pulmonary stretch receptors - prevent overinflation of the lungs
Irritant receptors - activate cough reflex
J receptors - respond to pulmonary oedema, pneumonia, emboli to increase ventilation and respiration

135

How does hypoxia affect ventilation?

Increases the sensitivity to CO2

136

Peripheral chemoreceptors

In the carotid body
Respond to reduced PaO2, low pH and high PCO2
Afferents travel in glossopharyngeal and vagus nerves

137

Cells of the carotid body

Glomus type I chief cells - release NTs to stimlate afferent nerves
Glomus type II substentacular cells - resemble glia and act as supporting cells

138

How do type I glomus cells detect hypoxia?

Decrease in arterial pH causes depolarisation of the cell membrane
Opens calcium channels
Causes release of NTs

139

Where is the respiratory centre?

Groups of neurones in the pons and medulla
Medullary centres found in the reticular formation

140

Where does the respiratory centre project to?

Reticulospinal tract

141

Where does the reticulospinal tract run?

Around the margin of the ventral horn

142

Sensory integrating centre of the respiratory centre

Nucleus of the solitary tract
Dorsal medulla

143

Motor output centre of the respiratory centre

Nucleus ambiguus
More ventrally positioned

144

Amount of haemoglobin in a typical erythrocyte

270 million molecules

145

How do RBCs produce energy?

No mitochondria
ATP by glycolysis
High lactate levels
Low IC pH

146

What are the 6 outer electrons in iron bonded to?

4 to the porphyrin ring
5th to histadine amino acid
6th free to bond to oxygen

147

Haemoglobin strecture

4 subunits
Each with a haem group attached

148

Methaemoglobin

Oxidised haemoglobin
Can be reversed by methaemoglobin reductase
Reason why red cells have a short lifespan

149

How does methaemoglobin formation lead to the cell being destroyed?

Changes markers on the RBC surface
Detected by liver and spleen cells
Cells are removed

150

Adult vs foetal haemoglobin

Adults = a2b2
Foetal = a2g2

151

Sickle cell disease

Defective form of haemoglobin, HbS, formed
HbS is a mutant form of one of the beta subunits
HbS aggregates and causes RBCs to change shape

152

Thalassaemia

Reduced rate or no synthesis of one the globin chains making up haemoglobin
Reduced oxygen transport
Can affect a or b subunits

153

What causes the oxygen dissociation curve to shift to the right?

Increased temperature
Decreased pH

154

Myoglobin

Single subunit
Greater affinity for oxygen than Hb
Acts as oxygen buffer store in muscles

155

How is carbon dioxide carried in the blood?

Converted to bicarbonate by carbonic anhydrase
Bicarbonate pumped out and exchanged for Cl- ion
Bicarbonate carried in venous blood to the lungs

156

How is carbon dioxide exhaled?

Bicarbonate re-enters the cell by exchange of Cl-
Converted back to CO2 by carbonic anhydrase

157

When can CO2 displace oxygen from haemoglobin?

In acid conditions

158

Neuronal sensors for blood pressure

In carotid sinus and aortic sinus

159

What does an increase in blood pressure cause?

Increase stretch of baroreceptors
Increased frequency of firing to vasomotor centre of medulla
Inhibits the vasomotor centre to reduce sympathetic outflow
Lowers heart rate and TPR
Lowers BP
Excitatory response to the cardioinhibitory centre
Increases vagal outflow to the heart

160

What does a decrease in blood pressure cause?

Decreased frequency of action potentials from baroreceptors
Increased output of vasomotor centre
Impulses down reticulospinal tract
Stimulate preganglionic sympathetic neurones to increase sympathetic outflow
Increases HR and TPR
Increases BP

161

Action of angiotensin II

Causes vasoconstriction to increase TPR to increase BP
Acts on the adrenal cortex to stimulate aldosterone release

162

Poiseuille's law

Small changes in diameter produce large changes in flow

163

Why does stagnant blood lead to clots?

When blood moves over the enodthelium it deflects polypeptide chains and causes nitric oxide release which relaxed and dilates the walls
With stagnant blood this doesn't happen so more likely to clot

164

Polycythemia

Increased haematocrit
Flow through vessels very slow
Can lead to end organ failure

165

Laplace's law

The smaller the radius of a vessel, the greater the pressure the wall can withstand

166

Mean pulmonary circulation pressure?

25/8

167

Starling's law

Ventricular contractile force increases with end diastolic volume

168

Preload

Degree of stretch in the ventricles during diastole

169

Afterload

Effective flow impedance of the aorta and large vessels that must be overcome for blood to be ejected from the heart

170

Isovolumetric contraction

When the ventricles contract but with no volume change
Occurs before valves often

171

Age and length of isovolumetric contraction

Longer
Results in smaller stroke volume
Due to reduced compliance of aorta due to loss of elasticity

172

3 main JVP waves

a = due to atrial contraction
c = tricuspid valve closing and bulging back slightly
v = valve bulging as ventricles contract

173

Cardiac pacemaker cell action potential

Constant inward sodium leak
Outward potassium leak with a rate that decays
Membrane slowly depolarises
Reaches the threshold value and triggers sodium influx and action potential fires

174

Effect of ANS on potassium leak

Parasympathetic - inhibits closure of potassium channels to slow down HR
Sympathetic - increases closure of potassium channels to increase HR

175

How long is the AVN delay

60ms

176

What is the normal PR interval?

120-200ms

177

What does a long PR interval indicate

First degree AV block

178

Ventricular muscle action potential?

Begins normally
Long plateau phase
Prolonged entry of calcium due to L type channels which are slow

179

Importance of cardiac refractory period

To ensure that the contractions do not merge into one
Keeps all the cells synchronous

180

ECG limb leads

I = right axilla--> left axilla
II = right axilla --> left leg
III = left axilla --> left leg

181

QRS complex length

182

P wave

Atrial depolarisation
Positive in I, II
Notched or peaked P waves seen in COPD and CHF

183

ST segment

When all ventricular muscles are contracting
Changes seen in MI

184

T wave

Repolarisation of the ventricles

185

Characteristic of aVR

Large Q wave with small R wave

186

Characteristic of aVL

Very small

187

Characteristic of V1

Mainly negative with large S wave

188

Characteristic of V5 and V6

Mainly positive with large R wave

189

Which leads give an anterior view of the heart?

V3,4

190

Which leads give an inferior view of the heart?

II, III, aVF

191

Which leads give a lateral view of the heart?

I, aVL, V5, V6

192

Which leads give a septal view of the heart?

V1, V2

193

ECG of AF

No P wave
Irregular R-R intervals

194

ECG of atrial flutter

Extra P waves

195

ECG of ventricular fibrillation

No clear QRS complexes

196

Proteins found in plasma

60% albumin
36% globulin
4% fibrinogen

197

Hb results in anaemia

198

Microcytic anaemia

MCV

199

Normacytic anaemia

MCV 80-100fL
Acute blood loss
Chronic disease
Renal failure
Leukaemia
Sickle cell anaemia

200

Macrocytic anaemia

MCV >100fL
B12/folate deficiency
Liver disease

201

Where are continuous capillaries found?

Throughout the body

202

Where are fenestrated capillaries found?

Exocrine glands
Intestines
Pancreas
Glomeruli of kidney

203

Where are sinusoidal capillaries found?

Liver
Spleen
Bone marrow

204

Filtration pressure at arterial vs venous end

10mmHg at arterial end - water forced out
-8mmHg at venous end - water pulled back in

205

What is responsible for oncotic pressure?

Large plasma proteins that cannot leave the blood

206

Filtration pressure in the lungs

7mmHg
Keeps the lungs damp and moist for optimal gaseous exchange conditions

207

How much lymph is returned to the circulation per day?

2-4L/day

208

Causes of oedema

Increased venous HPc in heart failure
Reduced capillary oncotic pressure in liver or kidney damage
Increased capillary permeability in burns
Obstruction of lymphatic drainage in fibrosis or filiariasis

209

Percent of plasma filtered through glomerulus

20%

210

Kidney blood flow

1.2L/min

211

Renal plasma flow

680ml/min

212

GFR

120-125ml/min

213

Urine flow

1ml/min

214

Net filtration pressure

10mmHg

215

Clearance formula

(urine conc x flow) / plasma conc

216

What is used to measure GFR?

Inulin as gold standard
Creatinine clinically but overestimates by 10-20% as some active secretion

217

What is used to measure RPF?

PAH

218

How is GFR increased?

Afferents relax and efferents constrict
Increases filtration pressure
Increases GFR

219

How is GFR decreased?

Afferents constrict and efferents relax
Lowers filtration pressure
Decreases GFR

220

When is renin released?

When macula densa cells sense a decrease in sodium concentration in the distal tubule fluid

221

What does renin do?

Cleaves angiotensinogen in the liver to angiotensin I

222

Where is angiotensin I converted to angiotensin II and by what?

In the lungs
By angiotensin converting enzyme

223

Neuronal volume sensors

Right and left atrium
Act as stretch receptors
Send signals via vagus nerve to the brainstem
In high blood pressure it inhibits sympathetic outflow

224

Hormonal volume sensors

Right atrium and IVC
Release ANP in response to stretching

225

Action of ANP

Decreases Na+ reabsoprtion in the distal tubule of the kindey

226

When is BNP released?

If the ventricles are very overstretched
Such as in heart failure

227

Which nuclei are responsible for ADH secretion

Supraoptic
Paraventricular

228

If osmoreceptors detect hypo-osmolarity...

Triggers renin release
Inhibits ADH release

229

If osmoreceptors detect hyper-osmolarity...

Stimulates ADH release

230

Water diuresis

Due to drinking too much water
ADH release inhibited
High volume of dilute urine

231

Osmotic diuresis

Sugars not completely reabsorbed in the proximal tubule
Glucose provides osmotic force pulling water into the urine
High volume of sugary urine

232

Pre vs post ganglionic neurones

Pre = small myelinated type B axons
Post = unmyelinated type C axons

233

Synapse between pre and postganglionic sympathetic neurones

Nicotinic ACh receptor

234

Adrenal gland as an exception to the rule

Gland acts as the postganglionic neurone
Receives stimulation by nicotinic receptors and ACh
Secreted adrenaline directly into the blood

235

Sweat glands as an exception to the rule

Use ACh as their postganglionic NT

236

Where are there no alpha adrenoreceptors?

In the heart or brain
Ensures constant blood flow to these organs

237

Alpha 1 adrenoreceptors

Increases vascular smooth muscle contraction
Contraction of ureter, vas deferens, uterus, urethral sphincter

238

Alpha 1 antagonists

Prazosin
Antihypertensives

239

Alpha 2 adrenoreceptors

Found in presynaptic sympathetci nerve terminals
Reduce NA release by negative feedback
Inhibit insulin release
Stimulate glucagon release
GI sphincter contraction

240

Alpha 2 agonists

Clonidine
Antihypertensives

241

Beta 1 adrenoreceptors

Increase heart rate and force of contraction
Increase renin and ghrelin secretion

242

Beta blockers

Propanolol, atenolol
Reduce heart rate and contraction force
Antihypertensives

243

Beta 2 adrenoreceptors

Relax bronchial smooth muscle
Decrease GI motility
Relaxation of detrusor muscle
Stimulate gluconeogenesis and glycogenolysis

244

Beta 2 agonists

Relax bronchial smooth muscle
Given to asthmatics

245

Beta 3 adrenoreceptors

Stimulate lipolysis
Found in adipose tissue

246

Sympathetic activity during exercise

Beta 2 and 3 stimulation increases glucose release from the liver and increases muscle uptake

247

HPA axis

CRH from hypothalamus
ACTH release from pituitary
Cortisol from adrenal cortex
Cortisol stimulates adrenaline and noradrenaline synthesis

248

How are cardiac myocytes joined?

By gap junctions and desmosomes

249

Define automaticity

Ability to initiate their own action potentials without the need of external stimuli

250

Cardiac calcium signalling

Depolarisation opens calcium channels
Influx of calcium through L type calcium channels
Rise in IC calcium triggers further release from the sarcoplasmic reticulum by ryanodine receptors
Calcium associates with troponin C to displace tropopmyosin
Allows actin-myosin cross bridges to form
Reuptake of calcium by SERCA

251

Multiunit smooth muscle

Each muscle receives its own synaptic input
Little electrical coupling
Allows for fine control and gradual responses
e.g. eyes

252

Single unit smooth muscle

Single cell within a sheet or bundle innervated
Action potential spreads through cells through gap junctions
Whole bundle/sheet contracts together
Found in walls of visceral organs

253

Calcium signalling in smooth muscle

Depolarisation opens voltage gated calcium channels and leads to calcium influx
Agonist induced calcium release via IP3
Calcium binds to calmodulin and activates myosin light chain kinase
MLCK phosphorylates myosin light chain regulatory region
Increases ATPase activity to allow cross bridge cycling

254

How many divisions are there in the airway tree?

23
First 16 divisions make up the conducting airways
Last 7 divisions make up the respiratory zone

255

What two forces hold the lungs and thoracic walls together?

Intrapleural fluid cohesiveness
Negative intrapleural pressure

256

Boyle's law

As the volume of gas increases the pressure decreases

257

Factors contributing to lung recoil

Elastic connective tissue
Alveolar surface tension

258

Anatomical dead space

Volume of conducting airways

259

Functional/physiological dead space

Anatomical dead space + non-perfused volumes of the respiratory airways

260

Alveolar oxygen partial pressure

100mmHg

261

Alveolar carbon dioxide partial pressure

40mmHg

262

Differences in lung flow at different levels

Apices = intermittent flow - during systole only
Centres = pulsatile flow - high during systole
Bases = continuous flow

263

Alveolar vs arterial vs venous pressures at lung levels

Apices = PA>Pa>Pv
Centres = Pa>PA>Pv
Bases = Pa>Pv>PA

264

What element is used to measure lung perfusion?

Xenon

265

Compliance formula

= dV/dP

266

Differences in compliance at different lung levels

Highest in the bases
Lowest in the apices
This means the bases are better ventilated

267

VQ ratios throughout the lung

Apices --> V/Q = 3.3
3rd rib --> V/Q = 1
Bases --> V/Q = 0.6

268

Decline in blood flow vs ventilation

Blood flow has a steeper decline than ventilation

269

Effect of pulmonary hypoxia

Vasoconstriction
Diverts blood away from under-ventilated areas of the lung

270

What happens to the pulmonary arterial resistance during exercise?

Decreases
Stretching due to high cardiac output generates a reflex relaxation
Increased ventilation increases arteriolar dilation

271

Causes of reduced lung compliance

Pulmonary fibrosis
Lung collapse
Increased pulmonary venous pressure

272

Causes of increased lung compliance

Age
Emphysema

273

Hysteresis

Inflation and deflation pressure/volume curves are different
Greater pressure required to reach a given volume during inflation compared to deflation

274

Average tidal volume

500ml

275

Average vital capacity

4-6L