PBL Topic 2 Case 6 Flashcards
(148 cards)
1
Q
Identify four functions of the circulation
A
- Transport nutrients to body tissues
- Transport waste away from body tissues
- To conduct hormones
- To maintain an appropriate environment in all tissue fluids
2
Q
Identify the two types of circulation
A
- Pulmonary circulation
- Systemic circulation
3
Q
Identify the function of the arteries
A
- Transport blood under high pressure to the tissues from the heart
4
Q
Identify the function of the arterioles
A
- Control conduits through which blood is released into the capillaries
5
Q
Identify the functions of the capilalries
A
- Exchange nutrients, electrolytes, hormones and other substances between the blood and interstitial fluid
6
Q
Identify the functions of the venules
A
- Collect blood from the capillaries into progressively larger veins
7
Q
Identify the functions of the veins
A
- Conduits for transport of blood from the venules back to the heart
8
Q
What is the arterial pressure in the aorta?
A
- 100 mm/Hg
- 80 mm/Hg during diastole
- 120mm/Hg during systole
9
Q
How does the arterial pressure change following the aorta?
A
- Decreases
- High enough to allow nutrients to diffuse through the pores
- Low enough to allow little plasma to leak through the pores
10
Q
What is cardiac output and what is its typical value?
A
- Quantity of blood pumped into the aorta each minute by the heart
- 5 L/min
11
Q
Identify two factors that determine blood flow
A
- Pressure difference
- Vascular resistance
12
Q
How do you calculate blood pressure?
A
- Cardiac Output x Peripheral Resistance
13
Q
How do you calculate cardiac output?
A
- Stroke Volume x Heart Rate
14
Q
How do you calculate stroke volume?
A
- End Diastolic Volume - End Systolic Volume
15
Q
Identify three factors that affect stroke volume
A
- Preload
- Contractility
- Afterload
16
Q
Identify three factors that affect heart rate
A
- Hormones
- Temperature
- Pain
17
Q
Identify three factors that affect vessel resistance
A
- Viscosity of the blood
- Vessel length
- Vessel radius
18
Q
Identify 5 factors that increase blood flow
A
- Increase in metabolism
- High altitudes
- Pneumonia
- Carbon monoxide poisoning
- Cyanide poisoning
19
Q
Outline Vasodilator Theory
A
- Increase in oxygen demand
- Formation of vasodilator substances
- Including histamine, adenosine and nitric oxide
20
Q
Outline Oxygen Lack Theory
A
- Increase in oxygen demand
- Natural dilation of vessels in absence of oxygen
- Cyclical opening of precapillary sphincters (vasomotion)
21
Q
Outline Reactive Hyperaemia
A
- Increase in oxygen demand
- E.g. occlusion
- Rapid blood flow through tissue for a few seconds
- Repay oxygen deficit
22
Q
Outline Active Hyperaemia
A
- Increase in oxygen demand
- E.g. exercise
- Rate of blood flow increases through vessel
23
Q
Outline Metabolic Theory of Auto-regulation of Blood Flow
A
- Rise in arterial pressure
- Excess flow of oxygen and nutrients
- Vasoconstriction
- Reduced blood flow
24
Q
Outline Myogenic Theory of Auto-regulation of Blood Flow
A
- Rise in arterial pressure
- Stretching of vessel
- Vasoconstriction
- Reduced blood flow
25
What stimulates nitric oxide release for vasodilation?
- Rapid flow of arteries causes sheer stress due to viscous drag
- Release of bradykinin and histamine
26
How does nitric oxide cause vasodilation?
- Combines with guanylyl cyclase
- Formation of cGMP
- A second messenger to activate protein Kinase G
- De-phosphorylation of myosin light chains
- Sequestration of intracellular Ca2+
27
What is the function of prostacyclin (Prostaglandin I2)?
- Vasodilator
28
What is the function of endothelin-1?
- Vasoconstrictor
29
What is EDRF?
- Endothelium Derived Relaxing Factor
- Composed of Nitric Oxide
- Vasodilator
30
Identify three factors that are responsible for angiogenesis
- Vascular Endothelial Growth Factor (VEGF)
- Fibroblast Growth Factor
- Angiogenin
31
Outline the process of angiogenesis
- Dissolution of basement membrane
- Reproduction of endothelial that stream outward through vessel
- Formation of cords that fold over into a tube
- Formation of a capillary loop when two tubes join
- Blood flow through capillary loop
- Invasion of smooth muscle cells
32
Outline the process of collateral circulation
- Dilation of small vascular loops that connect the vessel above to the blocked vessel below
- Dividing of these small vascular loops forming multiple small collateral channels
33
Identify two ways that noradrenaline can enter the circulation
- Release from sympathetic nerve endings
| - Sympathetic nerves cause adrenal medulla to secrete large amounts
34
Identify what occurs when noradrenaline binds to alpha receptors
- Activated G protein activates Phospholipase C
- PIP2 is converted into IP3 and DAG
- IP3 mobilises calcium ions which are involved in vasoconstriction
- DAG actives protein kinases which phosphorylate other proteins resulting in cellular response
35
Identify the function of a1 and a2 receptors and where they are located
- a1 receptors on smooth muscle cause vasoconstriction
| - a2 receptors on presynaptic membrane cause negative feedback
36
Identify what occurs when noradrenaline binds to beta receptors
- Activated G protein activates adenylyl cyclase
- Conversion of ATP to cAMP
- Activation of protein kinases
- Phosphorylation of proteins results in cellular response
37
Identify the function of B1, B2 and B3 receptors and where they are located
- B1 receptors on sinus node and cardiac muscle increase heart rate and contraction force
- B2 receptors on smooth muscle in coronary arteries cause vasodilation
- B2 receptors on airway smooth muscle cause bronchodilation
- B3 receptors cause lipolysis
38
What percentage of the cardiac output do the kidneys recieve?
- 20% (1L/min)
39
Where and how is renin stored?
- Stored as prorenin in juxtaglomerular cells of the kidneys
40
What is the function of renin?
- Acts on angiotensinogen to release
- To release 10-amino acid peptide angiotensin 1
- When arterial pressure falls
41
What is the role of Angiotensin Converting Enzyme? Where does this function take place?
- Conversion of Angiotensin I to Angiotensin II (8-amino acid peptide)
- Lung
42
Identify two functions of Angiotensin II
- Powerful vasoconstrictor
- Decrease sodium and water excretion
- Thereby increasing arterial pressure
43
What is the function of Aminopeptidase A?
- Removes a single amino acid from Angiotensin II
| - To form Angiotensin III
44
Identify two functions of Angiotensin III
- Stimulates aldosterone secretion
- Regulates thirst
- Increases secretion of ADH
45
How does Angiotensin II act on smooth muscle cells?
- Via Phospholipase C Second Messenger System
46
How is Angiotensin II inactivated?
- By angiotensinases
47
When is ANP secreted?
- Volume overload
| - In response to stretching of the atria
48
Identify four functions of ANP
- Increase diuresis and natriuresis
- Vasodilation
- Increase vascular permeability
- Inhibit release of angiotensin II
49
What is the affect of ANP on renal glomerular afferent and efferent arterioles?
- Dilation of afferent arterioles
- Constriction of efferent arterioles
- Increased filtration pressure
- Increases glomerular filtration
- Enhanced sodium excretion
50
Identify the three regions of the vasomotor centre
- Vasoconstrictor Area
- Vasodilator Area
- Sensory Area
51
Identify the function of the vasoconstrictor centre
- Excites preganglionic vasoconstrictor neurons of the sympathetic nervous system
52
Identify the function of the vasodilator area
- Fibres project upwards
| - Inhibit vasoconstrictor activity
53
Identify the function of the sensory area
- Receives sensory nerve signals from glossopharyngeal and vagus nerves
- Output from these helps to activate either the vasodilator or vasoconstrictor area
54
Identify the function of the lateral portions of the vasomotor centre
- Transmits impulses through the sympathetic nerve fibres to increase heart rate and contractility
55
Identify the function of the medial portions of the vasomotor centre
- Transmits parasympathetic impulses through the vagus nerve to decrease heart rate and contractility
56
Identify the main baroreceptors and their associated nerves
- Carotid baroreceptors, located in bifurcation of carotid artery, transmit signals via glossopharyngeal nerve (via Hering's nerves)
- Aortic baroreceptors, located in the aortic arch, transmit signals through vagus nerve
57
Identify an effect of increased blood pressure on the vasomotor centre and sinus onde
- Stimulation of caridioinhibitory centre
- Inhibition of cardioaccelerator
- Increased parasympathetic activity and decreased sympathetic activity to sinus node
- Decrease in heart rate
58
Identify the effect of decreased blood pressure on the vasomotor centre and sinus node
- Stimulation of cardioaccelerator centre
- Inhibition of caridioinhibitory centre
- Increased sympathetic activity and decreased parasympathetic activity to sinus node
- Increase in heart rate
59
Explain why nicotine can stimulate postganglionic neurons
- Membranes of these neurones contain nicotinic receptors
60
Explain how chronic nicotine use contributes to cardiovascular disease
- Nicotine stimulates noradrenaline and adrenaline from adrenal medulla
- Sympathetic components result in tachycardia, and increased cardiac output
- Persistent high blood pressure and increased work on the heart
61
Why does the effect of nicotine persist for many minutes to several hours?
- Nicotine is note destroyed by cholinesterase
62
What is meant by hypertension?
- Chronic elevation of arterial blood pressure
63
What is essential hypertension?
What is the percentage of cases of hypertension where this applies?
- Hypertension in which a specific underlying cause cannot be found
- 95%
64
What is secondary hypertension?
What is the percentage of cases of hypertension where this applies?
- Hypertension as a consequence of a specific underlying disease
- Leading to sodium retention and peripheral vasoconstriction
- 5% of cases
65
In which ethnic groups is hypertension most common?
- Black Americans
| - Japanese
66
Outline how to measure blood pressure
- Ensure machine is validated and properly calibrated
- Remove tight clothing from arm and support the arm at the level of the heart
- Use appropriate size cuff
- Lower the blood pressure slowly (2mm/Hg per second)
- Use phase V (disappearance of sounds) to measure diastolic BP
67
What are the optimal, normal and high normal blood pressures?
- Optimal = 120/80
- Normal = 130/85
- High Normal = 140/90
68
What are the blood pressures for Grade 1, Grade 2 and Grade 3 hypertension?
- Grade 1 = 150/95
- Grade 2 = 160/100
- Grade 3 = 180/110
69
Identify six non-humoral causes of hypertension?
- Genetic influence
- Low birth weight
- Obesity
- Alcohol intake
- Sodium intake
- Acute pain or stress
70
Identify three hormonal systems that have been implicated in the pathogenesis of hypertension?
- Renin-angiotensin
- Natriuretic
- Kallikrein-kinin
71
Outline the changes that occur in resistance vessels in the pathophysiology of hypertension
- Increase in wall thickness
- Rarefaction (decreased density)
- Resulting in increased peripheral resistance and left ventricular hypertrophy
72
Outline the changes that occur in larger vessels in the pathophysiology of hypertension
- Thickening of the media
- Increase in collage
- Secondary deposition of calcium
- Resulting in loss of arterial compliance
73
Outline the changes that occur in the renal vasculature in the pathophysiology of hypertension
- Reduced renal perfusion
- Activation of angiotensin II by renin-angiotensin system
- Reduced glomerular filtration rate
- Reduction in natriuresis and diuresis
74
Outline the cerebral changes that occur in the pathophysiology of hypertension
- Lacunae and reversible neurological deficits
| - Resulting in dementia and stroke
75
Identify the two main causes of death in hypertension
- Cerebrovascular Disease
| - Coronary Artery Disease
76
What is malignant hypertension?
- Blood pressure rises rapidly
- With characteristic fibrinoid necrosis
- Which leads to renal failure, heart failure, aortic dissection or stroke
77
Identify 6 investigations that should be carried out in hypertensive patients
- Urinalysis for blood, protein and glucose
- Blood glucose
- Blood urea, electrolytes and creatinine
- Serum total and HDL cholesterol
- Fasting blood for lipids
- 12-lead ECG
78
Identify specific investigations carried out when urea and creatinine are elevated and what they are used to detect
- Renal ultrasound to detect kidney disease
| - Renal angiography to detect renal artery stenosis
79
Identify specific investigations carried out when ECG shows evidence of coronary artery disease and what they are used to detect
- Echocardiogram to detect left ventricular hypertrophy
| - CXR to detect cardiomegaly or heart failure
80
How do the target blood pressures of hypertensive patients differ between those with and without diabetes?
- Without diabetes: 140/85
| - With diabetes: 130/80
81
What is the threshold for offering drug treatment to hypertensive patients?
- BP > 160/100
or
- BP > 140/90 and 10-year CVD risk of at least 20% or existing CVD or target organ damage
82
Identify five lifestyle measures than obviate the need for drug therapy in hypertensive patients
- Correcting obesity
- Reducing alcohol intake
- Smoking cessation
- Taking regular exercise
- Increased consumption of fruit, vegetables and oily fish
83
Identify the four classes of drugs that are used to treat hypertension
- ACE Inhibitors e.g. Ramipril
- Beta Blockers e.g. Bisoprolol
- Calcium Channel Blocker e.g. amlodipine
- Diuretic e.g. Chlortalidone
84
What is the treatment given to young caucasians in Step 1 and why is this the case?
- ACE Inhibitor
| - These patients are more likely to have renin hypertension
85
What is the treatment given to older or black patients in Step 1 and why is this the case?
- Calcium Channel Blocker or Diuretic
| - These patients are more likely to have low renin hypertension
86
What is the rationale for Step 2 in the treatment of hypertension?
- Two drugs of different groups are used
- E.g. Ace Inhibitor and Calcium Channel Blocker
- E.g. Ace Inhibitor and Diuretic
87
What is the rationale for Step 3 in the treatment of hypertension?
- ACE Inhibitor is combined with a calcium-channel blocker and diuretic
- Beta blocker may be used if this is not sufficient to achieve target blood pressure
88
Outline the mechanism of action of thiazide diuretics
- Bind to Cl- site of the distal tubular Na/Cl co-transport system
- Natriuresis and Diuresis
- Reduced blood pressure and vasodilation
89
In which patients are thiazide diuretics ineffective?
- In patients with glomerular filtration rates below 30 mL/min
90
Identify the main unwanted effect in thiazide diuretics
- Erectile dysfunction
91
When are angiotensin II receptor antagonists prescribed?
- In patients who are intolerant to ACEI
| - Since they do not affect bradykinin metabolism or produce cough
92
Outline the mechanism of action of angiotensin II receptor antagonists
- Block the formation of angiotensin II, a powerful vasodilator
- Inhibit secretion of aldosterone resulting in natriuresis
- Reducing vascular resistance, improving tissue perfusion and reducing cardiac afterload
93
Identify the main unwanted effect in ARAs
- Hypotension
- Hyperkaleamia (less water = increased [K+] (relative concentration))
- Renal dysfunction
94
Identify three contra-indications for ARAs
- Pregnancy
- Renal artery stenosis
- Previous angioedema
95
Identify an example of a calcium channel blocker
- Amlodipine,
| - Which belongs to the dihydropyridine class
96
- Identify the mechanism of action calcium channel blockers
- Bind to a1 subunit of L-type calcium channel
- Preventing it from opening
- Reducing influx of Ca2+
- Resulting in coronary dilation
97
Why do calcium channels demonstrate use/voltage-dependence?
- Block more effectively in cells in which the calcium channels are most active / depolarised
98
Identify three side effects of calcium channel blockers
- Flushing
- Headaches
- Ankle swelling
99
What causes the ankle swelling caused by calcium channel blockers?
- Arteriolar dilation
| - Increased permeability of post-capillary venules
100
What is a Background Question?
- General questions about a clinical problem or disease process
101
What is a Foreground Question?
- Questions centred around an individual patient
102
What does the acronym PICO stand for?
- P = Patient / Problem
- I = Intervention
- C = Comparison / Control
- O = Outcome
103
What is primary literature?
- Original reports of research studies
- Published in scientific journals
- Used to help answer complex foreground questions
104
What is a Bibliographic Database?
- Collection of primary literature
105
Identify four examples of Bibliographic Databases
- Medline
- PubMed
- PsycInfo
- EMBASE
106
What is a Secondary Source of Evidence?
- Evidence regarding a particular question that has already been searched for and appraised
107
Identify four examples of Secondary Sources of Evidence
- Cochrane Library
- BestBETs
- Essential Evidence Plus
- Clinical Evidence
108
Identify four examples of Secondary Journals
- ACP Journal Club
- Evidence Based Medicine
- Clinical Inquiries
- Bandolier
109
What are categorical variables and how are they summarised?
- Qualitative variables
- In a frequency distribution
- As bar graphs or pie charts
110
What are numerical variables and how are they summarised?
- Quantitative variables
- In a frequency distribution with intervals and ranges
- As histograms or frequency polygons
111
What is meant by the term Central Tendency?
- A single numerical capturing the typical distribution
112
What is the mean and how is it calculated?
- Mathematical term for average
| - Dividing the sum of all values by the number of observations
113
What is the median and how is it calculated?
- Middle observation
| - When the data are ranked in increasing order
114
What is the mode?
- The value that occurs most often
115
What is spread?
- The degree by which the values are clumped around a measure of central tendency
116
How is the range calculated? What is the limitation of the range?
- Difference between the highest and lowest value
| - Does not give any indication for intermediate values
117
What does the standard deviation show?
- Indication of the degree to which the values are clumped around the mean
118
Approximately what percentage of values fall within 1SD?
- 68%
119
Approximately what percentage of values fall within 2SDs?
- 95%
120
Approximately what percentage of values fall within 3SDs?
- 99.7%
121
Identify three causes of outliers and when it is acceptable to exclude outliers in the final statistical analysis
- Measurement
- Interpretation
- Calculation
- If the outlier is caused by one of the above factors
122
What is a test statistic? How is this related to critical value?
- A numerical summary of the data
| - Test statistic must be greater than critical value for hypothesis to be statistically significant
123
What does the null hypothesis state?
- When one variable is tested against another, there will be no difference / association between the variables
124
What is the p value?
- Probability of observing the results of a trial if the null hypothesis is true
- p value close to 1 indicates a correct null hypothesis
- p value close to 0 indicates an incorrect null hypothesis
125
A p value of less than X is usually considered to be statistically significant
- X = 0.05
126
What does the Shapiro Wilk (W) test show?
- Whether data is normally distributed
127
What is skewness and how is this shown on a distribution curve?
- Measure of asymmetry of the distribution
- Positive = Distribution skewed to right (p on its back)
- Right = Distribution skewed to left
128
What does the T-test (T) show?
- Difference between two means
129
When is the one sample T-test used?
- To compare a sample mean with the population mean(e.g. junior doctors compared to population)
130
When is the unpaired T-test used?
- To compare a mean in two independent groups (e.g. smokers vs non-smokers)
131
When is the paired T-test used?
- To compare a mean of a single group at two separate points in time (e.g. before and after treatment)
132
What is the difference between a one- and two-tailed tailed T-test?
- Two-tailed assumes that the results may go in either direction
- One tailed means good reason to predict direction of difference
133
What is the Pearson's Correlation Coefficient (R)
- How two variables are related
134
What is the difference between positive and negative correlation?
- Positive = As one variable increases so does the other
| - Negative = As one variable increases the other decreases
135
Identify two statistical packages used to help give a value for the correlation and p value?
- StatsDirect
| - SPSS
136
How are correlations presented?
- Scatter plots
137
What is linear progression
- Method used to predict the value of one variable from another known variable
138
How is linear progression calculated?
- Straight line that best fits data
- Two circles representing two data points are then drawn as a possible regression
- The arrows illustrate the deviation of variance of the data points
139
What is a forest plot?
- Graphical depiction of pooled treatment result
| - From a meta-analysis, where results of different studies are pooled together?
140
How is the Point Effect Estimate represented on a Forest Plot?
- Blue square of each study
| - Size is proportional to statistical weight of each study
141
How is the Overall Effect Estimate represented on a Forest Plot?
- Black diamond
142
What is the confidence interval and how is the confidence interval of each study represented?
- Certainty of point effect estimate
| - Each horizontal line
143
Identify two factors that narrow the confidence interval
- Large samples
| - Reduced variability
144
How can you tell that there is a significant difference between two treatments based on the confidence interval?
- The confidence interval does not cross the vertical line of no effect
145
What are the odds of an event and how is it calculated?
- Probability of an event not occurring
| - (Number of Events / Number of Patients - Number of Events)
146
What is the risk of an event and how is it calculated?
- Probability of an event occurring
| - (Number of Patients / Number of Events)
147
What does an odds or risk ratio greater than 1 indicate?
- Increased risk or odds among the exposed compared to the unexposed
148
What does an odds or risk ratio less than 1 indicate?
- Decreased risk or odds among the exposed compared to the unexposed
