6. CARDIOVASCULAR SYSTEM II Flashcards
Structure and function of the heart. Blood pressure, cholesterol and pulse. Signs, symptoms, investigation procedures and some orthodox treatments of common heart and blood vessel pathologies.
Describe the difference between ‘systemic circulation’ and ‘pulmonary circulation’
‘systemic circulation’ is the blood from the heart that is distributed around the body before returning to the heart and ‘pulmonary circulation’ is the blood going from the heart to the lungs and back to the heart.
Name the three layers present in blood vessels
Tunica externa - layer of elastic + collagen fibres
Tunica media - layer of smooth muscle
Tunica intima - single layer of endothelium
Where is the majority of blood found in the body?
Veins and venules (64%)
Explain the role of the portal vein
The portal vein collects blood from the spleen, pancreas and digestive system and takes it to the liver for filtering before it returns to the heart
Name the three layers of the heart wall and their main functions
Pericardium: Outer layer of of the heart that keeps it in position in the thorax and allows it to move freely without friction
Myocardium: The middle muscular layer that pumps the blood
Endocardium: The innermost layer that provides a smooth lining for the heart chambers and valves.
Name the predominant fuel used by cardiac muscle
Fatty acids (50-70%) [Glucose 30%]
Describe the role of the Sino-atrial node
It is the ‘pacemaker’ of the heart and initiates cardiac contraction
What is meant by ‘pulse rate’
A blood pressure wave originating from the heart
What is the average adult pulse rate
70-90 bpm
Define ‘cardiac output’
The volume of blood being pumped out by the heart per minute
Explain the following terms:
a. Tachycardia
b. Bradycardia
c. Systole
d. Diastole
a. Tachycardia: Resting heart rate over 100bpm
b. Bradycardia: Resting heart rate under 60bpm
c. Systole: The force that drives blood out of the heart (contraction)
d. Diastole: Period of relaxation when the heart fills with blood.
Name two functions of cholesterol
- Plays an integral role in cell membranes (especially in the brain)
- Vital component of sex hormones (i.e. oestrogen & testosterone)
- Plays an important role in Vitamin D and Calcium metabolism
How is cholesterol transported around the body?
Since cholesterol is hydrophobic, it is transported around the body as lipoproteins (bound to proteins)
Explain the function of:
a. Low density lipoproteins (LDLs)
b. High density lipoproteins (HDLs)
a. Carries 75% of cholesterol in the blood from the liver to the cells of the body (when in excess it can deposit it in the arteries)
b. Removes excess cholesterol from cells and blood and transports it back to the liver (prevents accumulation of cholesterol in the blood)
Define atherosclerosis
A type of arteriosclerosis, it is the thickening and loss of elasticity of arterial walls
Outline the pathophysiology of atherosclerosis
- Damage of vascular endothelium: inflammation
- LDLs deposit on tunica intima, oxidises and attracts phagocytes
- Macrophages surround fatty material and create foam cells in trying to destroy it.
- Proliferation of smooth muscle cells
- Cap is formed to wall it off from the blood =arterial narrowing
Name the heart layer that contains cardiac muscle.
Myocardium
Explain what is meant by ‘auto-rhytmic’
The heart generates its own rhythm of contraction
List the four chambers of the heart
Right atrium
Right ventricle
Left atrium
Left ventricle
Is the right or left ventricle thicker?
Left
Give a detailed description of the flow of blood in the heart from entering via the right atrium to exiting via the aorta. Include all key structures and indicate if blood is oxygenated or deoxygenated.
Deoxygenated blood enters the right atrium via the superior and inferior vena cava. From here the blood is pumped into the right ventricle through the tricuspid valve. From the right ventricle the blood is pumped to the lungs through the pulmonary valve into the pulmonary trunk that branches into left and right pulmonary arteries. In the lungs the blood is oxygenated and flows to the left atrium via the pulmonary vein. The oxygenated blood then flows through the bicuspid / mitral valve into the left ventricle from where it is pumped through the aortic valve into the ascending aorta to the rest of the body as well as th coronary arteries that carry blood to the heart wall.
Describe the role of ‘ductus arteriosum’?
During foetal life (eight weeks+), a temporary blood vessel called the ductus arteriosum shunts blood from the pulmonary trunk to the aorta.
Explain how the following affects heart rate and contraction as well as blood vessels:
a) Sympathetic nervous system
b) Parasympathetic nervous system
a) Increases rate and strength
of contraction; causes vasoconstriction
b) Decreases rate and strength of contraction (via vagus nerve); little influence on blood vessels
List FOUR factors that influence heart rate and strength
Hormones, age, sex, body position, exercise, stress and temperature all influence heart rate and strength
Describe the role of the Sino-atrial node
The SA node is the ‘pacemaker of the heart’ - sets rate and rhythm - and it initiates cardiac conduction
Indicate where the Sino-atrial node is located in the heart
It is located in the right atrial wall
Describe in specific detail the conduction system in the heart, commencing with the Sino-atrial node (include all key structures and their functions)
- Sinoatrial node (SA node):
The SA node sets rate and rhythm of the heart.
From the right atrial wall, it initiates cardiac conduction.
Each action potential from the SA node propagates through each atrium via gap junctions, causing atrial contraction. - Atrioventricular node (AV node):
A relay station which conducts impulses at a slightly slower rate to allow the atria to finish contracting.
Located in the bottom right of the interatrial septum. - Atrioventricular bundle (‘bundle of His’):
Located just below AV node, it is the only site where action potential can conduct from atria to ventricles. - Right and left bundle branches:
From the bundle of His, the action potential enters the left and right bundle branches, which extend the interventricular septum towards the apex of the heart. - Purkinje fibres:
Finally the Purkinje fibres rapidly conduct the action potential beginning at the apex of the heart, up the remainder of the ventricular myocardium causing ventricular contraction.
Which type of respiration does cardiac muscle require?
Aerobic
Name the predominant fuel used by cardiac muscle?
Fatty acids (50-70%)
Name the product that the heart can use to produce ATP during exercise.
Lactic acid
Explain what is meant by ‘pulse rate’
The pulse is a blood pressure wave originating from the heart. The rate varies depending on the stage of life
What is the average adult pulse rate?
70 to 90 bpm
Describe the difference between a ‘P wave’ and ‘T wave’ detected by an ECG.
The P wave represents atrial depolarisation (from SA node) while the T wave is ventricular repolarisation (resting).
Define cardiac output
Cardiac output is the volume of blood being pumped out by the heart per minute
Explain the following terms:
a. Tachycardia
b. Bradycardia
c. Systole
d. Diastole
a. Resting heart rate over 100 bpm.
b. Resting heart rate under 60 bpm.
c. The force that drives blood out of the heart (contraction).
d. Period of relaxation when the heart fills with blood.
Name TWO organs which have the highest priority for blood in the body
Heart and brain
Name TWO functions of cholesterol
Cholesterol is a vital compound for cell structure and function. It is in every body cell.
Some of its functions are:
• Cell membrane integrity (vital in the brain).
• Vitamin D and calcium metabolism.
• Production of sex hormones (e.g. oestrogen, testosterone)
Describe how cholesterol is transported around the body
As cholesterol is hydrophobic, it needs to
be transported around the body — it is bound to proteins and transported as lipoproteins
Explain the function of the following:
a. Low density lipoproteins (LDLs)
b. High density lipoproteins (HDLs)
a. LDLs carry 75% total cholesterol in blood, transporting it from the liver to cells of the body.
b. HDLs remove excess cholesterol from body cells and blood and transport it to the liver, thus preventing accumulation of cholesterol in blood
List FOUR causes of hypercholesterolemia
- ‘Familial’ (defect on chromosome 9, causing an inability to remove LDL from blood).
- Age-related (risk increases with age).
- Hypertension.
- Diabetes mellitus (and insulin resistance)
- Obesity.
- Smoking.
- Sedentary lifestyle.
- Diet (high trans fats, table salt, refined sugars)
- Excessive alcohol.
Describe in detail the pathophysiology of atherosclerosis
- Damage of the vascular endothelium occurs, creating inflammation.
- LDLs deposit in the damaged tunica intima and are oxidised, subsequently attracting phagocytes.
- Macrophages surround the fatty material in an attempt to destroy it and create foam cells.
- There is a proliferation of vascular smooth muscle cells.
- A cap is formed over the atherosclerotic plaque to wall off the plaque from the blood.
Name FOUR dietary/lifestyle causes of atherosclerosis
smoking
stress
sedentary lifestyle
excessive alcohol
Describe TWO main ways that atherosclerosis presents clinically
- Angina pectoris/Myocardial infarction - ischaemic heart pain (from thrombosis and embolism).
- Stroke/Transient Ischaemic Attack (from thrombosis, embolism and haemorrhage).
Explain why an embolism is a serious complication of atherosclerosis
An embolism is a mobile blood clot which travels
through the blood and causes a blockage which could result in a myocardial infarction or stroke
Describe the main difference between a ‘stroke’ and ‘transient ischaemic attack (TIA)’
A stroke is a disruption of blood supply to the brain which can cause irreversible cell damage. Signs of cerebral damage lasts more than 24 hours.
A TIA is a temporary inadequacy of circulation to part of the brain which gives similar clinical picture to stroke but lasts no longer than 24 hours.
Name TWO causes of stroke
• Thrombus / embolus (80%) = ischaemic stroke.
• Haemorrhagic stroke — blood vessel damage;
(i.e. following ruptured aneurysm).
List THREE characteristic signs / symptoms of stroke
Sudden weakness, numbness / tingling,
loss of speech, loss of vision, sudden severe headaches, confusion, unsteadiness.
Name the brain location where berry aneurysms typically occur
In the centre of the cerebrum
Using definitions, compare ‘deep vein thrombosis (DVT)’ with ‘varicose veins’
DVT is thrombus formation in the deep veins of the legs which may dislodge and cause a pulmonary embolism.
Varicose veins are due to incompetent valves which cause pooling of the venous blood and chronically dilated veins.
Name TWO risk factors that cause DVT by:
a. Reducing blood flow
b. Changing blood nature
a. immobility, pressure on vein by tumour, shock, long-haul flights
b. dehydration, polycythaemia, sticky platelets, oral contraceptive pill
List TWO signs / symptoms of DVTs
Limb pain, calf swelling, tenderness along vein, distension of superficial veins, increased skin temperature and local redness (erythema)
Name ONE positive sign identified in DVT
Positive D-Dimer test
Define haemorrhoids
Enlarged and often inflamed veins in the anal canal
List TWO causes of haemorrhoids
- Chronic constipation, chronic cough.
- Hypertension (portal hypertension).
- Obesity, pregnancy.
List TWO characteristic signs / symptoms of haemorrhoids
- Painless unless they become strangulated.
- Bright, red blood on faeces / toilet paper.
- Protruding haemorrhoids causing pain and itching.
Name ONE cause of oesophageal varices
- Portal hypertension (e.g. secondary to liver cirrhosis).
* Right-sided heart failure.
Define Raynaud’s syndrome
Intermittent attacks of ischaemia in extremities.
List ONE rheumatological cause of Raynaud’s syndrome
Rheumatoid Arthritis
List THREE characteristic signs / symptoms of Raynaud’s syndrome
- Vasospasm followed by hyperaemia.
* Pallor, cyanosis, redness. Pain.
Name TWO cardiovascular causes of oedema
Heart failure
DVT
List TWO causes of ascites
- Liver cirrhosis (80%) — due to portal hypertension.
- Malignancy of stomach, colon, pancreas, ovary.
- Heart failure.
- Constrictive pericarditis (fibrotic pericardium).
List TWO signs / symptoms of ascites
- Abdominal distension and later discomfort.
- Nausea and supressed appetite.
- Dyspnoea.
Define hypertension
High blood pressure (UK) — 140 / 90mmHg or higher
Name TWO primary causes of hypertension
Generally lifestyle and family history.
Obesity, age, smoking, lack of exercise, stress.
Name ONE secondary cause of hypertension
renal disease, diabetes
Name TWO complications of hypertension
- Cardiovascular events, heart failure, aneurysm.
- Chronic kidney disease (CKD).
- Stroke.
- Cognitive decline and cerebral oedema.
- Premature death.
- Retinal (eye) damage.
Explain how the brain is affected by hypotension
Leads to inadequate blood supply to the brain
List ONE sign / symptom of postural hypotension
Fainting / dizzy on standing up too quickly due to delayed response of the baroreceptors to the change in blood pressure on standing.
Name ONE cause of hypotension
Shock, Myocardial Infarction, blood loss, long-term adrenal fatigue, anti-hypertensives
List TWO causes of heart failure
- Coronary heart disease and hypertension are the most common causes.
- Valve diseases causes 10% cases; e.g. aortic stenosis.
- Often secondary to a myocardial infarction.
Which type of heart failure is associated with pulmonary oedema?
Left-sided heart failure
Name TWO signs / symptoms of the following:
a. Acute heart failure
b. Chronic heart failure
a. Acute: chest pain, pain radiating into the jaw, neck and left arm. Shortness of breath, weakness, dizziness, overwhelming anxiety (medical emergency).
b. Chronic: may be asymptomatic. Dyspnoea, fatigue, oedema, fluid retention, cardiomegaly, cyanosis (due to poor circulation of oxygen in blood).
Explain the main difference between ‘valve stenosis’ and ‘valve regurgitation’
Valve stenosis is the fibrosis and calcification of valve(s) leading to obstruction to blood flow through heart chambers.
Valve regurgitation is inadequate valve closure causing leakage.
Define angina pectoris
Ischaemic heart disease due to obstruction or spasm of the coronary arteries
Describe the pathophysiology of angina pectoris
The symptoms associated with angina result from the demands of the myocardium not being met by its blood supply; e.g. due to atherosclerosis or vascular spasm.
Describe the difference between ‘stable’ and ‘unstable’ angina pectoris
In stable angina the pain is precipitated by physical exercise.
Unstable angina occurs randomly.
Name TWO characteristic signs / symptoms of angina pectoris
- Heavy, constricting chest pain, radiating to the neck, left shoulder and jaw. Eases on rest.
- Dyspnoea.
Using definitions, compare ‘myocardial infarction’ and ‘cardiac arrest’
Myocardial infarction ('heart attack') is the necrosis (death) of myocardial tissue due to ischaemia.
Cardiac arrest occurs when the heart develops an arrhythmia causing it to stop.Name the most COMMON cause of myocardial infarction
Usually due to blockage of a coronary artery by a thrombus
Describe the pain associated with myocardial infarction
Severe chest pain (central, radiating to the left arm, neck or jaw). Pressure, sharp.
Define atrial fibrillation
Atrial fibrillation is the most common cardiac arrhythmia (irregular heart rhythm).
Using definitions compare ‘endocarditis’ and ‘pericarditis’
Endocarditis is the inflammation of the endocardium and valves. Pericarditis is acute inflammation of the pericardium.
Explain what is meant by ‘Osler’s nodes’
Osler’s nodes (red tender spots under skin of fingers) is a sign of endocarditis.
Name ONE viral cause of pericarditis
Flu
List TWO signs / symptoms of pericarditis
- Chest pain: Radiating to the back and relieved by sitting up and forward. Worsened by lying down or breathing deeply.
- Dyspnoea when reclining, low-grade fever, weakness, fatigue and feeling nauseous, dry cough, oedema (abdominal / leg).
- Pericardial friction rub.
Describe ‘cardiac tamponade’, a complication of pericarditis
Cardiac tamponade (pericardial effusion): Fluid collects in the pericardium, putting pressure on the heart, inhibiting it from filling completely.
Define ‘shock’
A reduction in circulating blood volume, blood pressure and cardiac output, resulting in hypoxia of the tissues.
List TWO characteristic signs / symptoms of shock
Hypoxia — cold, clammy, cyanosis, faint, weak, confusion, anxiety, tachycardia, weak pulse, rapid breathing, hypotension.
