137 Questions
Which ECG lead is mainly negative and placed on the right side of the sternum?
V1
What is the normal duration of the QRS complex?
<100ms
What is the normal PR interval range?
120-200ms
Which of the following is NOT a characteristic of a P wave?
Negative in leads I, II, III
What is the purpose of drawing a triangle using the QRS complex from two leads?
To determine the cardiac vector
In which lead is the Q wave usually small or absent? if QRS heads upwards
Lead II
What is the purpose of labeling the vertical axis in units of pressure in a diagram of the pressure profiles?
To quantify the pressure changes
Which ECG lead is placed at the anterior axillary line and is mainly positive?
V6
What is the effect of increased preload on stroke volume?
Increased stroke volume
What is the relationship between compliance and afterload?
High compliance corresponds to low afterload
What happens to the elasticity of the aorta in older people?
It decreases
What is the effect of an enlarged heart on ventricular contraction?
Ventricles contract more weakly
What is the term for the force of contraction of ventricular muscle?
Inotropy
What is the normal end-diastolic volume (EDV)?
120 ml
What is the effect of increased afterload on the period of isovolumetric contraction?
It increases
What is the primary function of the cohesive forces of the intrapleural fluid?
To hold the lungs and chest wall together
What occurs when intrapleural pressure becomes equal to or exceeds atmospheric pressure?
The lung collapses
What is the primary component of the connective tissue in the walls of alveoli?
Elastic fibers
What is the term for the ability of the lungs to be stretched?
Lung compliance
What is the significance of the slope of the curve in the volume-pressure curve?
It represents lung compliance
What is the term for the phenomenon where lung volume at any pressure during inhalation is lower than during expiration?
Hysteresis
What is the effect of age and emphysema on lung compliance?
It increases lung compliance
What is the result of an increase in fibrous tissue in the lung?
Decreased lung compliance
What is the primary function of fenestrated capillaries?
To facilitate bulk exchange of solutes and water
Which type of capillary has the highest permeability?
Sinusoidal/discontinuous capillaries
What is the primary mechanism by which digoxin increases contractility in the heart?
It decreases the activity of the Na/K ATPase pump, leading to increased calcium levels
What is the primary mechanism of solute exchange in capillaries?
Diffusion
What is the primary consequence of angina pectoris in the myocardial muscle?
Increased oxygen demand exceeding supply
What is the function of the basement membrane in capillaries?
To provide structural support to the capillary wall
What type of capillary is characterized by the presence of numerous transport vesicles?
Capillaries in skeletal muscle
What is the primary effect of nitrates on the cardiovascular system?
Vasodilation and decreased preload
What is the primary mechanism of action of beta adrenoceptor antagonists in reducing oxygen demand in the myocardium?
Decreased heart rate and contractility
Which of the following is NOT a characteristic of sinusoidal/discontinuous capillaries?
Presence of smooth muscle
What is the primary function of the metarteriole in the microcirculation?
To direct blood flow to the capillary bed
What is the primary mechanism of action of statins in reducing cholesterol levels?
Inhibition of HMG Co-A reductase
What is the difference between continuous capillaries and fenestrated capillaries?
The size of the fenestrations
What is the primary function of PCSK9 inhibitors in reducing LDL cholesterol levels?
Inhibition of PCSK9, leading to increased LDL receptor activity
What is anaemia, in the context of blood and haematology?
A decrease in the amount of haemoglobin in the blood
What is the percentage of extracellular fluid composed of plasma?
20%
What is the typical percentage of haemoglobin bound to O2 in a normal individual?
96-99%
What is the term for the condition where the arterial oxygen saturation is below 90%?
Hypoxaemia
What is the function of the 2, 3 DPG in the centre of the haemoglobin?
Enhances the ability of RBCs to release O2
What is the difference between the oxygen haemoglobin dissociation curve and oxygen saturation?
The curve describes oxygen binding to haemoglobin, while saturation is the proportion of haemoglobin bound to O2
What is the consequence of gradual methaemoglobin formation?
Decreased oxygen binding to haemoglobin
What is the difference between adult haemoglobin and foetal haemoglobin?
Foetal haemoglobin has a higher affinity for oxygen
What is the function of the iron atom in the haem group?
Forms 4 covalent bonds with nitrogen atoms in the porphyrin ring
What is the consequence of a congenital deficiency of methaemoglobin reductase?
Polycythaemia
What is the approximate volume of the dead space in the respiratory system?
150-200ml
What is the primary function of the ciliated pseudo-stratified columnar epithelium in the trachea and bronchi?
To trap dust and bacteria
What is the formula for calculating the partial pressure of a gas in a mixture?
Partial pressure = total pressure in gas mixture x fractional concentration of gas
What is the primary function of the Type II alveolar cells in the alveoli?
To produce surfactant
What is the approximate total cross-sectional area of the respiratory zone?
Rapidly increasing
What is the primary function of the macrophages in the alveoli?
To trap dust and bacteria
What is the composition of surfactant produced by the Type II alveolar cells?
Phospholipoprotein
What is the primary function of the mucociliary elevator in the respiratory system?
To move mucus up towards the throat for swallowing
What is the primary reason for the difference in pressure between the systemic and pulmonary circulation?
The difference in the total vascular resistance
What is the primary solute exchange mechanism in capillaries that allows for the movement of small molecules like H2O and ions?
Diffusion
What type of capillary has a continuous closed basal lamina but contains small circular pores, allowing for the free passage of H2O and salts from plasma to tissue?
Fenestrated capillaries
What is the effect of an increase in blood delivered to the atria on the force of contraction of the ventricle?
The force of contraction increases
What is the primary function of the large diameter and thin elastic walls of the pulmonary arteries?
To reduce pressure
Which of the following is a characteristic of sinusoidal/discontinuous capillaries?
Highest permeability and largest fenestrations
What is the effect of a decrease in preload on the cardiac output?
Cardiac output decreases
What is the purpose of the basement membrane in capillaries?
To provide structural support to the capillary wall
What is the primary function of the metarteriole in the microcirculation?
To direct blood flow from the arterioles to the venules
What is the primary characteristic of systemic capillaries compared to pulmonary capillaries?
Smaller diameter
What is the primary mechanism of fluid movement between the plasma, interstitium, and lymph?
Capillary pressure, plasma colloid osmotic pressure, and interstitial colloid osmotic pressure
What is the mechanism by which the heart is able to pump out all the blood that is delivered into the atria?
The overlap of filaments at rest
What is the term for the ability of the lungs to be stretched, which is affected by the elasticity of the aorta in older people?
Compliance
What is the effect of an increase in afterload on the cardiac output?
Cardiac output decreases
What is the primary significance of the difference in pressure between the systemic and pulmonary circulation?
To ensure blood flow to the rest of the body
What is the primary consequence of an increase in fibrous tissue in the lung, which can lead to oedema?
Decreased lung compliance
What is the primary function of Glomus type I cells?
To release neurotransmitters to stimulate CN IX and CN X
What is the primary stimulus for activation of J receptors?
All of the above
What is the effect of stimulating irritant receptors?
Cough reflex
What is the primary response of peripheral chemoreceptors to low oxygen levels?
Depolarization of glomus membrane
What is the primary function of the reticular formation of the medulla?
Regulation of ventilation
What is the primary difference between peripheral and central chemoreceptors?
Central receptors respond to O2, while peripheral receptors respond to CO2
What is the primary role of the glossopharyngeal nerve in respiratory control?
Transmission of signals from peripheral chemoreceptors
What is the threshold for activation of peripheral chemoreceptors in response to hypoxia?
PO2 less than 60 mm Hg
What is the primary function of dense bodies in smooth muscle cells?
Transmission of force generated by contraction
What is the primary mechanism by which calcium ions trigger muscle contraction in smooth muscle?
Binding to troponin C in the sarcomere
What is the primary function of gap junctions in smooth muscle cells?
Providing a pathway for the passage of electrical signals
What is the primary characteristic of multiunit smooth muscle?
Each cell receives synaptic input
What is the primary location of single unit smooth muscle?
Bladder and gut
What is the primary function of varicosities in smooth muscle cells?
Releasing neurotransmitters
What is the primary difference between multiunit and single unit smooth muscle?
Synaptic input received by each cell
What is the primary mechanism of contraction in smooth muscle cells?
Binding of calcium to troponin C
What is the primary function of the sensory fibres found in the right atrium and left atrium?
To detect changes in blood volume
What is the name of the hormone released by specialized muscle cells in the right atrium and inferior vena cava?
Atrial natriuretic peptide
What percentage of blood is stored in the capillaries and veins?
65%
Where are the osmoreceptors located that measure osmotic pressure of blood?
Supraoptic and paraventricular nuclei
What is the effect of increased thirst on blood volume regulation?
Increased fluid intake
What is the primary function of the neurons that measure blood volume?
To regulate blood volume
What is the effect of atrial natriuretic peptide on the kidney?
Decreased reabsorption of fluid
Where do the neurons that measure blood volume send information to?
NTS
Which part of the adrenal gland secretes adrenaline?
Medulla
What is the function of the sympathetic nervous system in regulating blood pressure during exercise?
It increases heart rate to compensate for vasodilation
What is the characteristic of postganglionic nerve fibers in sweat glands?
They are cholinergic
What is the term for the low-level tonic activity of the sympathetic nervous system?
Basal tone
Which of the following is NOT a function of the sympathetic nervous system?
Stimulating the parasympathetic system
What is the location of the pre-vertebral ganglia, also known as sympathetic ganglia?
Below the diaphragm
What is the path of some preganglionic neurons in the adrenal gland?
They travel out to the adrenaline nerve
What is the function of the sympathetic nervous system in regulating blood flow to the brain and heart?
It has no effect on blood flow to the brain and heart
What is the primary function of Inspiratory Reserve Volume (IRV)?
To forcibly inhale air after inspiration of normal tidal volume
What is the volume of air that can be taken into the lungs in full inhalation?
Inspiratory Capacity (IC)
What is the term for the maximum amount of air a person can expel from the lungs after maximum inhalation?
Vital Capacity (VC)
What is the term for the volume of air remaining in the lungs after maximal exhalation?
Residual Volume (RV)
What is the calculation for Inspiratory Capacity (IC)?
IRV + TV
What is the term for the amount of air a person breathes per minute?
Minute Ventilation
What is the device that measures airflow rather than air volume?
Vitalograph
What is the term for the volume of air in the lungs at the end of passive expiration?
Functional Residual Capacity (FRC)
What is the primary reason for the difference in partial pressures of oxygen between alveolar gas and mixed pulmonary venous blood?
The efficient transfer of oxygen between alveoli and blood.
What is the effect of changing breathing rate on oxygen saturation?
It has no effect on oxygen saturation.
What is the primary function of the cohesive forces of the intrapleural fluid?
To resist being pulled apart.
What is the primary reason for the negative intrapleural pressure?
The sub-atmospheric pressure between the lung surface and the inner chest wall of the thorax.
What is the effect of inspiration on intrapleural pressure?
It decreases intrapleural pressure.
What is the primary reason for the difference in oxygen partial pressure between the apices and the bases of the lungs?
The difference in blood flow between the apices and bases.
What is the effect of changing breathing rate on CO2 excretion?
It increases CO2 excretion.
What is the primary reason for the difference in CO2 partial pressure between the alveoli and pulmonary venous blood?
The difference in CO2 transport between the alveoli and pulmonary venous blood.
What is the volume of air that can be taken into the lungs in full inhalation?
3700 mL
What is the term for the volume of air remaining in the lungs after maximal exhalation?
Residual Volume
What is the maximum amount of air a person can expel from the lungs after maximum inhalation?
4800 mL
What is the instrument used to measure airflow?
Vitalograph
What is the volume of air breathed in and out at rest?
0.5 L
What is the volume of air that can be forcibly inhaled after inspiration of normal tidal volume?
3100 mL
What is the significance of creatinine being actively secreted by the glomerulus?
It leads to overestimation of GFR by 10-20%
What is the role of PAH in measuring renal plasma flow?
It is used to measure RPF
What is the significance of erythropoietin releasing cells being in the kidney?
They regulate oxygen carrying capacity of the blood
What is the primary reason for the difference in oxygen partial pressure between the apices and the bases of the lungs?
Ventilation perfusion mismatch
What is the primary function of the thick-walled, ascending limb of the loop of Henle?
It plays a key role in producing concentrated or dilute urine
What is the term for the force that opposes the contraction of ventricular muscle?
Afterload
What is the approximate partial pressure of oxygen in alveolar gas?
100 mm Hg
What is the effect of incorporating water vapor in alveolar gas on the total pressure?
It decreases the total pressure
What is the osmolarity of blood plasma?
300 mOsm
What is the highest partial pressure of oxygen found in the lungs?
160 mm Hg
What is the primary factor that maximizes gas transport in the lungs?
All of the above
What is the effect of altitude on the partial pressure of oxygen?
It decreases the partial pressure of oxygen
Learn about the placement and overview of different ECG leads, including V1-V6, and how they view different regions of the heart. Understand the importance of each lead and how they work together.
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