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Cardiorespiratory Flashcards

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1
Q

Tunica intima structure

A

Endothelium layer
Loose CT
Internal elastic lamina

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2
Q

Tunica intima structure

A

Endothelium layer
Loose CT
Internal elastic lamina

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3
Q

Tunica media structure

A

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

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4
Q

Tunica adventitia

A

Loose CT

Vaso vasorum

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5
Q

Endocardium structure

A

Inner endothelium lining

Supporting highly elastic fibrocollagenous CT

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6
Q

Myocardium structure

A

Cardiac myocytes linked by intercalated discs

Supporting fibrocollagenous CT

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7
Q

Epicardium structure

A

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

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8
Q

Elastic arteries

A

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

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9
Q

Muscular arteries

A

Medium to small sized arteries

Have the basic arterial structure

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10
Q

Which types of cells form foam cells

A

Macrophages and smooth muscle cells

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11
Q

What does the fibrous cap consist of?

A

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

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12
Q

Upper respiratory tract

A

Mouth –> larynx

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13
Q

Lower respiratory tract

A

Trachea –> terminal bronchioles

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14
Q

Classic respiratory epithelium

A

Pseudostratified columnar, ciliated epithelium with mucous secreting goblet cells

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15
Q

How does the epithelium change throughout the lungs?

A

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

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16
Q

Epithelium in the pharynx

A

Stratified squamous

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17
Q

Immune properties of the respiratory tract

A

Mucociliary escalator

MALT

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18
Q

Trachea layers

A 
Respiratory epithelium
Lamina propria - with elastin and lymphoid tissue
Submucosa - with many glands
C shaped rings of hyaline cartilage
Adventita
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19
Q

Bronchi structure

A 
Shorter epithelial cells 
Lamina propria contains more elastic tissue
Muscularis mucosae begins to form 
Fewer submucosal glands
Cartilage in plates rather than rings
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20
Q

Tertiary bronchi structure

A

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

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21
Q

Bronchiole structure

A 
Ciliated columnar epitehlium
Few goblet cells 
Clara cells 
Prominent muscularis mucosae
No cartilage 
No mucous glands
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22
Q

Respiratory bronchiole structure

A

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

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23
Q

Alveolar cell types

A

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

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24
Q

Blood-air barrier

A

Type I pneumocyte
Basement membrane
Capillary endothelium

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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

1 - FINALS (6 decks)

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