Cardiovascular ll

Question 1

ECG: What does an electrocardiogram do?

Answer 1

Records the electrical conduction system of the heart. It represents the electrical activity of the hearts depolarisation and repolarisation during the cardiac cycle

Question 2

What are the three distinct waveforms on an ECG machine?

Answer 2

P wave, QRS complex, T wave

Question 3

What does the P wave on an ECG measure?

Answer 3

The depolarisation of the atria

Question 4

What does the QRS complex on an ECG machine measure?

Answer 4

The depolarisation of the ventricles

Question 5

What does the T wave on an ECG measure?

Answer 5

The repolarisation of the ventricles of the heart

Question 6

What are the four main ECG rhythms?

Answer 6

1. Ventricular Tachycardia (VT)
2. Ventricular Fibrillation (VF)
3. Asystole
4. Pulseless electrical activity (PEA)

Question 7

Where does ventricular tachycardia originate?

Answer 7

The ventricles of the heart

Question 8

What is ventricular tachycardia?

Answer 8

Fast heart rate - rhythm between 120-300BPM

Question 9

What causes Ventricular Tachycardia + what makes it dangerous?

Answer 9

Abnormal electrical signals in the ventricles of the heart. This can be dangerous as it can reduce cardiac output + diminishes blood flow to the body, can lead to VF, drop BP or cause fainting

Question 10

What is ventricular fibrillation (VF)?

Answer 10

The fibrillation/quivering of the ventricles of the heart - there are no normal contractions of the ventricles

Question 11

What causes ventricular fibrillation + what makes it dangerous?

Answer 11

VF is caused by chaotic/disordered electrical activity in the ventricles of the heart. This means that the heart pumps little or no blood around the body, and can lead to cardiac arrest if not treated immediately

Question 12

What is asystole?

Answer 12

The absence of electrical activity within the heart (there is no pulse). The heart is unable to generate/distibute electrical pulses

Question 13

What is pulseless electrical activity (PEA)?

Answer 13

This means electrical activity is present, but there is mechanical issues with the heart, and the heart is not strong enough to pump blood to the body

Question 14

What are the two shockable ECG rhythms (that have been taught)?

Answer 14

Ventricular Tachycardia and Ventricular Fibrillation

Question 15

What are the two non-shockable rhythms (that have been taught?)

Answer 15

Pulseless electrical activity (PEA), and Asystole (flatline)

Question 16

Why are PEA and asystole non-shockable rhythms?

Answer 16

PEA already has organised electrical activity. Because AED shocks to restore abnormal electrical activity, shocking here won’t help. In Asystole, there is no electrical activity within the heart, and since there is nothing to reset, a shock will not help

Question 17

What should you focus on for non-shockable rhythms in cardiac arrest?

Answer 17

CPR, and looking for reversible causes… (These are the four H’s and four T’s)

Question 18

What are the ‘Four H’s and four T’s)?

Answer 18

Four H’s:
- Hypo/Hyperkalemia (Low/high potassium/ion levels)
- Hypoxemia (Low partial oxygen levels in blood)
- Hypo/Hyperthermia (low/high body temp)
- Hypovolemia (low fluid volume in body)

Four T’s:
- Tamponade (cardiac): (fluid builds up around the heart, making it difficult to pump blood)
- Tension Pneumothorax (Air builds up in pleural space of the lungs)
- Toxins (/poisons/drugs)
- Thrombosis (pulmonary or coronary) - blood clot forming in the vessels

Question 19

What is the physiology behind CPR?

Answer 19

CPR generates blood flow around the heart, as well as systemically to vital organs. The compressions on the chest decrease the volume of the chest cavity, increasing pressure. This increase in pressure on the heart forces blood to flow out of heart and into circulation. Circulatory system only flows one way, so decompression then allows blood to be drawn to the heart to fill the space. CPR essentially acts as a mechanical pump for the heart.

Question 20

What is the definition of arrythmia?

Answer 20

A condition where the heart beats with an irregular or abnormal rhythm

Question 21

What is the physiology behind an AED machine?

Answer 21

An AED is a device that delivers a controlled shock to correct the arrhythmia of the heart. The shock interrupts the abnormal heart rhythm allowing the SA node to regain control and restore normal rhythm.
When used sequentially with compressions, the compressions maintain organ function and the AED delivers the treatment to restart the heart.

Question 22

What are crucial components for successful resuscitation?

Answer 22

Early AED and continuous compressions

Question 23

What does the term ‘cardiac cycle’ mean?

Answer 23

This refers to the events of one complete heartbeat

Question 24

What happens in a full cardiac cycle?

Answer 24

Both atria and ventricles contract and relax. First atria contract, and as they relax, ventricles contract. As most of the pumping of the heart is performed by the ventricles, the terms systole and diastole refer to the contraction and relaxation of the ventricles. The contraction and relaxation of the heart chambers produce different sounds.

Question 25

What are the two distinct heart sounds - what causes those sounds?

Answer 25

There are 2 distinct sounds during each cardiac cycle - described as “lub” “dup”... - Lub sound is caused by the closing of the AV valves - Dup sound is caused when the semilunar valve closes at the end of systole - The first sound is longer and louder - The second sound is short and sharp

Question 26

What does the term 'cardiac output' refer to? (CO)

Answer 26

The amount of blood pumped out of/ejected from the left ventricle over the span of one minute

Question 27

What two factors influence cardiac output?

Answer 27

Stroke volume (SV) and heart rate (HR) - SV: the amount of blood pumped out of the heart in a single contraction - HR: how many times the heart beats in one minute

Question 28

What does the term 'preload' refer to?

Answer 28

The stretch in the walls of the ventricles/the filling of blood in the ventricles (*an increase in filling/stretch is described as increases preload*) - reduced filling/stretch results in decreased preload (dehydration)

Question 29

What does the term 'afterload' refer to?

Answer 29

The pressure the ventricles must build up. Force against with which the heart has to eject blood out of the left ventricle through the aortic valve, and the right ventricle through the pulmonary valve **(The higher the pressure required to force the valve open the higher the afterload – vasoconstriction*)

Question 30

What does the term 'contractility' refer to?

Answer 30

The force of contraction of the muscles of the ventricles. Increased force of contraction = increased SV = increased CO Increased contractility is stimulated by the body to increase CO when an increase in demand arises – runner etc*

Question 31

Physiology: Regulation of heart rate Where are cardiovascular control centres found in the brain?

Answer 31

In the medulla oblongata - found at the base of the brain where it connects with the spine (specifically at the level of the foramen magnum***)

Question 32

Physiology: Regulation of heart rate What are the two centres in the cardiovascular control centre that influence heart rate?

Answer 32

1. The cardioacceleratory centre - which increases HR through the sympathetic nervous system 2. The cardioinhibitory centre - which decreases HR through the parasympathetic nervous system

Question 33

Physiology: Regulation of heart rate What does the baroreceptor reflex do?

Answer 33

Detects change in stretch of major blood vessels (BP) + controls heart rate to restore homeostasis (***example of a negative feedback loop**) - A rise in BP – increase the parasympathetic activity and decrease sympathetic – causing blood vessels to dilate and HR decrease Reverse if the BP is to low

Question 34

Physiology: Regulation of heart rate Where are baroreceptors located + why?

Answer 34

In the walls of the aortic arch + carotid sinuses. The location of the baroreceptors are ideal for monitoring systemic (aortic) blood pressure becasue they are located at major blood distribution points (carotid sinus at the bifurcation of the carotid arteries that supply blood to the brain and eyes, and the aortic arch where the aorta supplies blood to the rest of the body and major organs after leaving the heart)

Question 35

Physiology: Blood vessels - What is the vascular system + function?

Answer 35

A closed transport system that blood flows around inside the body

Question 36

What are the components of the vascular system?

Answer 36

Blood, blood vessels (including arteries/arterioles, veins/venules + capillaries (+ the heart itself)

Question 37

Where are neural receptors found in the lungs?

Answer 37

In the vagal nerves - *specifically in the afferent fibres of the vagus nerve*

Question 38

What do neural receptors in the lungs do?

Answer 38

Neural receptors in the lungs are sensory detectors. *They constantly monitor what's happening in the lungs and send signals to the brain to help regulate breathing + heart rate, protect the airways, and respond to changes like stretching, irritation, or fluid buildup. - Neural receptors in the lungs (vagal nerves*) cause HR to increase during inspiration and decrease during expiration – sinus arrhythmia

Question 39

What is respiratory sinus arrythmia?

Answer 39

Normal variations in the heart rate due to breathing. Inspiration (inhaling) typically increases heart rate, while expiration (exhaling) decreases it. This fluctuation is linked to changes in vagal nerve activity and cardiac filling pressures during the respiratory cycle.

Question 40

Where are dendrites found within the lungs?

Answer 40

**Dendrites are found in neurons within the pulmonary plexus, which is part of the vagal nerve innervation of the lungs

Question 41

How do dendrites in the lungs affect heart rate regulation?

Answer 41

Dendrites of the vagal nerve are stretched during inspiration and inhibit the cardioinhibitaroy centre, allowing the sympathetic acceleration of heart rate. The increased pressure during inspiration feeds this and also assists in venous return to the heart from the abdominal veins, increasing heart rate again.

Question 42

What is the bainbridge reflex?

Answer 42

**The Bainbridge reflex, also known as the atrial reflex, is a cardiovascular reflex that increases heart rate in response to increased stretching of the right atrium and inferior vena cava, caused by increased venous return (or after IV infusion)

Question 43

Physiology: Cardiac Innervation What is an authorhythmic cell?

Answer 43

A cell that is influenced by the autonomic nervous system

Question 44

Physiology: Cardiac Innervation Why are cardiac cells autorhythmic?

Answer 44

As they are influenced by the autonomic nervous system

Question 45

Physiology: Cardiac Innervation What is the rate of SA node depolarisation controlled by?

Answer 45

The parasympathetic and sympathetic neurons of the ANS

Question 46

Physiology: Cardiac Innervation What does the stimulation of the SA node by the parasympathetic nervous system do?

Answer 46

Rapidly increases heart rate by Noradrenaline and adrenaline interacting with β 1 (beta 1 )-adrenergic receptors on the cardiac muscle cell membranes. Effect is an increased influx of calcium, which increases the contractile strength of the heart and increases the speed of electrical impulses through the heart muscle and the nodes... *** How noradrenaline or adrenaline reaches SA node: Brain activates sympathetic nervous system 2 Signal travels down spinal cord (T1–T5) 3 Preganglionic neurons synapse in ganglia 4 Postganglionic neurons release noradrenaline 5 Noradrenaline binds to β₁ receptors on SA node → heart rate ↑***

Question 47

Physiology: Cardiac Innervation How does the Paraympathetic nervous system affect heart rate?

Answer 47

Through the vagus nerve - which releases a neurotransmitter called acetycholine. Acetylcholine causes decreased heart rate and slows the conduction through the AV node, prolonging intranodal conduction time.

Question 48

Physiology: Cardiac Innervation What is the function of a neurotransmitter?

Answer 48

To transit signals between nerve cells (neurons),, and other cells in the body

Question 49

Physiology: Cardiac Innervation (NOTES**) The heart action is also influenced by substances delivered to the myocardium in the coronary circulation. Nutrients and oxygen are needed for cellular survival and normal function, whereas hormones and other substances affect the strength and duration of myocardial contraction and the degree and duration of myocardial relaxation. Normal or appropriate function depends on the availability of these substances, which is why coronary heart disease can seriously disrupt heart function.

Question 50

Physiology: Blood Vessels What is the vascular system?

Answer 50

The vascular system is a closed transport system that blood circulates around inside the body

Question 51

What is the pathway of blood through the vascular system?

Answer 51

(After going through the pulmonary and systemic systems, the blood flows through the aorta as part of the systemic system, and blood then moves into smaller arteries; carrying blood away from the heart. These then branch off into arterioles (even smaller arteries), and then into capillary beds (which exchange gases, nutrients and wastes with the tissues), the capillary beds are then drained by venules (smallest veins), which empty into veins, which empty into the great veins (Vena Cavae), where the deoxygenated blood is returned to the heart in the right atrium). NOTE: arteries become arterioles when the lumen size narrows to less than 0.5mm

Question 52

What is the difference between the vascular and the venous systems?****

Answer 52

The vascular system refers to the closed transport system consisting of arteries, arterioles venules, veins and capillaries. In comparison, the venous system refers specifically to veins and venules, and the flow of deoxygenated blood back through the heart.

Question 53

How many layers are blood vessels composed of? What are they called?

Answer 53

Three layers: 1. Tunica externa (outermost/external layer) 2. Tunica media (mid layer) - A lot thicker in arteries than in veins as arteries cope with a higher pressure of blood being pumped directly from the heart itself 3. Tunica intima (innermost layer endothelial that lines the vessel lumen)

Question 54

What makes blood vessel walls vary in thickness?

Answer 54

This depends on the thickness or absence of one of more of the three layers that make up blood vessels (tunica externa, intima and media)

Question 55

How are the larger blood vessels in the body nourished?

Answer 55

Via the vasa vasorum ('vessels of the vessels*) - smaller blood vessels located on the tunica externa layer of blood vessels.

Question 56

What is the difference between muscular and elastic arteries?

Answer 56

- Muscular arteries are medium-sized and small arteries and are further from the heart than the major elastic arteries (e.g aora, pulmonary arteries)... - By the time blood reaches the muscular arteries, the major fluctuations in blood pressure have decreased substantially. - Muscular arteries have more muscle fibres than the elastic arteries because they require less stretch and recoil. - Muscular arteries distribute blood to arterioles throughout the body and help control blood flow because their smooth muscle can be stimulated to contract or relax. - Contraction narrows the vessel lumen — vasoconstriction — which diminishes flow through the vessel. Conversely, when the smooth muscle layer relaxes — vasodilation — more blood flows through the vessel lumen

Question 57

Arterioles: NOTES The arterioles are composed almost exclusively of smooth muscle and regulate the flow of blood into the capillaries in two ways: arteriole vasoconstriction, which limits the flow of blood into the capillaries; arteriole vasodilation, which permits blood to enter the capillaries freely. The thick smooth muscle layer of the arterioles is a major determinant of the resistance blood encounters as it flows through the systemic circulation

Question 58

What are the two types of capillary bed vessels? What are their functions?

Answer 58

1. True capillaries - These branch from arterioles and provide exchange between tissue and capillary blood (actual exchange vessels) 2. Vascular Shunts - Short vessels that directly connect arterioles and venules at opposite ends of the bed, allowing for bipass.

Question 59

Veins - NOTES Veins are low-pressure vessels, veins are thin-walled and fibrous and have a larger diameter Located more superficial and some easily seen and palpated on the body surface The smallest venules closest to the capillaries have an inner lining, composed the tunica intima and surrounded by fibrous tissue. The largest venules are surrounded by smooth muscle fibres constituting a thin tunica media. Veins are also more numerous than arteries. In veins, the tunica externa has less elastic tissue than in arteries, so veins do not recoil after distension as quickly as do arteries