CV Flashcards
What is a Haematocrit
The volume of blood cells in blood, it is also referred to as the packed cell volume, so the normal haematocrit is 0.45
Give a composition of blood with a percentage of its components
Fluid plasma - 55%
Cells - 45% (erythrocytes 44%, white blood cells and platelets 1%)
What causes the red bloods to become bi-concave discs
The loss of the cell nucleus causes the red blood cells to become bi-concave discs
In human, how many red blood cells are there
4 to 6 million erythrocytes per ml of blood
Give the diameter of a red blood cell
7 to 7.5 micrometers (um)
What is a reticulocytes and how much of the circulating red blood cell population does it make up
Reticulocytes are immature red blood cells and make up less than 1% of circulating red blood cells, they usually might have visible ribosomes still in them
Categorise the white blood cells into two groups, describing each type
Granulocytes
Neutrophil (ploymorphonuclear leukocytes) 40 - 75% = most numerous, phagocytotic and multilobar (number of lobes increases with age), can survive in hostile environments like low oxygen, contains myeloperoxidase because they use respiratory burst
Eosinophil (acidophilic leukocytes) about 5% = bi-lobar or tri-lobar with dark pink granules (losenge-shaped with crystalline cores- Charcot-leyden crystals), highest in the morning and numbers change, can phagocytose and associated with parasites, neutralise action of histamine, has receptors for IgE
Basophils (basophilic leukocytes) about 0.5% = contain large blue granules, similar role to mast cells, secretes histamine and vasoactive substances that increase blood flow to the local area, very rare, involved in anaphalactic shock
Agranulocytes
Lymphocytes (T and B) 20-50% = it is not possible to differentiate between T and B lymphocytes by just using a stain but immunohistochemistry can differentiate them
Monocytes 1-5% = kidney shaped (reniform) nucleus, differentiate into tissue macrophages
Give the 3 types of granules within a neutrophil and what they do
Type 1 - lysosomes involved in digestion of phagocytosed material e.g myeloperoxidase and acid hydrolases, most numerous (not unique to neutrophils)
Type 2- secretions from neutrophil involved in inflammatory response (unique to neutrophils)
Type 3 - contains enzymes (gelatinases and adhension molecules) which when secreted by the cell facilitate the insertion of proteins into the membrane of cell surface, this allows the neutrophils to squeeze between cells
What do the four types of platelet granules contain and what are their functions
Alpha granules = contain clotting factors
Delta granules = contains serotonin which is absorbed into them after discharge of clotting factors
Peroxisomes = contains catalase, an enzyme used to eliminate oxygen radicals
What is plasma
Plasma is blood without all the cells, it includes
Water
Salt and minerals
Plasma proteins (albumins, globulins, fibrinogen)
Hormones, signal molecules and other clotting factors
Makes up about 55% of blood
What is serum
Serum is plasma without clotting factors
Where are blood cells produced and destroyed
They are produced in the liver (in a foetus) and in the bone marrow (in adults)
They are destroyed in the liver and the spleen
Give the role of spectrin in red blood cells
Spectrin is an important protein in the endoskeleton of red blood cells
Give the different types of B and T lymphocytes and what they do
B cells - produce antibodies
T Helper (TH) cells - help B cells and activate macrophages
T Cytotoxic (TC) cells - kill previously marked target cells
T Suppressor (TS) cell - suppress TH cells and hence suppress the immune response
Natural Killer (NK) cells - mainly kill virus infected cells
Give the different cells that monocytes differentiate into
Tissue macrophages - everywhere Antigen presenting cells - everywhere Kupffer cells - liver Osteoclasts - bone Alveolar macrophages - lung
What is the progenitor cell for platelets
Megakaryocyte
What is hematopoiesis and where are all blood cells derived from
Hematopoiesis is the formation of the blood cells
All blood cells are derived from a pluripotent (multipotential) hematopoietic stem cell ( a hemacytoblast)
The haemacytoblast gives rise to common myeloid progenitor cells and he common lymphoid progenitor cells
Cardiac and voluntary (skeletal) muscle appear similar in many respects but (a) how do they differ structurally? (b) how do they differ physiologically? Try to think of 3 differences in each category
Structually
- interclated discs in cardiac muscle only
- single nucleus in cardiac muscle instead of syntitium of skeletal muscle
- central nucleus
Physiologically
- cardiac muscles are myogenic so dont need nerves
- secrete atrial natiuretic peptide hormone (NPH)
What does atrial natriuretic peptide do?
Atrial natriuretic peptide hormone is secreted by the atrium, it is released when cells are excessively stretched
It inhibits renin secretion
It increases the excretion of sodium, water and potassium in the kidneys
Which are smaller myocytes in the atrium or the ventricle
Myocytes in the atrium are smaller because of less resistance and workload
What are contained in the electron dense granules and alpha granules of platelets
Electron dense granules
- ADP
- Serotinin
- Calcium ions
Alpha granules
- platelets derived growth factor (PDGF)
- heparin antagonist factor (PF4)
- Von willebrand factor (vWF)
- Fibrinogen
Where are the sino atrial node and atrioventricular node located
The sino atrial node is located on the medial side of the superior vena cava at its junction with the right atrium
The atrioventricular node is located at the base of the inter-atrial septum, anterior to the opening of the cardiac sinus
Where are the purkinje fibres found and give some characteristics they have
They are found under the endocardium in the interventricular septum
They have large vacuoles an large stores of glycogen so stain magenta with a PAS stain
There is a delay between the contraction of the atria and the ventricles. What physical features cause this delay?
Rings of fibrous tissue between the atrium and ventricle prevent direct passage of an electrical signal so signal has to go through only the AV node which delays the signal slightly
Describe the structure of valves and change in the structure can lead to damage
The valves are made from thick collagen fibres and covered by a layer of endothelial cells
Damage to the valves can cause excessive collagen scarring leading to stenosis or regurgitation (incompetence)
What do the chordea tendinae do
The chordea tendinae anchor the valves to the papillary muscles
- allowing the contraction of the papillary muscles to open the valves
- preventing everting of the valves during ventricle contraction
Give conditions that can damage the heart valves
Calcification due to advanced age (mainly affects aortic valve)
Rheumatic fever (mainly affects aortic and mitral valve)
Staphylococcus aureus infection causing infective endocarditis
Rupture of papillary muscles making the valves incompetent
Describe the layers in the valve and what type of connective tissue they contain
Aortic side
- a layer of endothelial cells
- fibrosa (dense fibrous connective tissue)
- spongiosa (loose fibrous connective tissue) - contains interstitial cells, smooth muscle cells, fibroblasts and myofibroblasts
- ventricularis (collage and elastin)
- a layer of endothelial cells
What is endomysium
The loose fibrous connective tissue between the cadiac myocardium cells
Describe the 4 layers of the heart histology
The heart is inside the pericardial sac
Pericardium
- the lining of the pericardiac sac is the parietal pericardium
- the lining of the heart is the visceral pericardium
- outermost layer of the heart
Epicardium
- adipose tissue containing nerves and coronary vessels
Myocardium
- thickest layer and contains myocytes
- striated, interclated discs, branched and central nuclei
Endocardium
- innermost layer of the heart
- a layer of endothelial cells on a basement membrane with loose fibrous connective tissue
How does a defective valve lead to heart failure
A defective valve can either be incompetent allowing blood regurgitation back into the preceding heart chamber or be stenosed increase afterload
These both mean the heart cannot meet the metabolic needs of the body so hypertrophies
The heart still cannot sufficiently circulate the blood which leads to heart failure
Describe how the interatrial septum is formed and what the fossa ovalis signifies
In foetal development, the lungs are not fully funtional
- the increased resistance means that there is great pressure in the right side of the heart than left so blood moves down the concentration gradient
- at the 4th week, the septum primus (thin tissue) starts to develop between the two atria
- perforations called formen secondum develop in the septum primus before it totally separates the atria
- the septum secondum (thicker tissue) develops to the right of the septum primus
- another perforation called the foramen ovale develops in the side of the septum secondum
- the septum primus starts to disintegrate but still covers the foramen ovale
- the septum primus is now called the valve of the foramen ovale because when blood is travelling from the right atrium to the left it pushes the valve to the side
At first, when the baby takes it’s first breath, the lung fill up with air decreasing the pressure on the right side of the heart so the left side is higher
The high pressure in the left side of the heart pushes the valve of the foramen ovale against the septum secondum and they fuse within the first 3 months of a child’s life
The foramen ovale is called the fossa ovalis
The fossa ovalis in an adult heart signifies where the valve of the foramen ovale permanently covered the foramen ovale
Describe the division of the atrioventricular canal to form two precursors to the atrioventricular valves
While the interatrial septum is forming, the atrioventricular canal starts to divide
The primordial atrium and primordial ventricle fuse (two endocardial tubes fuse) to become one heart tube, the heart begins to fold and starts beating (day 22)
Endocardial cushions (masses of tissue on either side of the atrioventricular canal) start to pinch the middle of it, dividing it into two
The percursors for the atrioventricular valves are now formed
Describe the development of the aorta, pulmonary trunk and the interventricular septum
At this point, blood flowed from the right and left atrium through the atrioventricular canals into the primordial ventricle and through the truncus arteriosus
By the end of the 4th week, a muscular septum starts to grow superiorly from the base of the ventricle
It stops before the atrioventricular canals which still have the gap created by the endocardial cushions between them
By the end of the 5th week, two ridges (called conotruncal ridges or tuncoconcal swellings) start to grow from the truncus arteriosus
The conotruncal ridges grow superiorly and form a spiral which becomes the articopulmonary septum, it divides the truncus arteriosus into the aorta and pulmonary trunk
The articopulmonary septum also grows inferiorly and fuse with the endocardial cushion (that form the interventricular foramen) and the muscular ventricular septum (this finishes by the end of week 8)
Blood now flows from the right atrium to the right ventricle and into the pulmonary trunk, and from the left atrium to the left ventricle and into the aorta
Describe the development of the aortic arch vessels and when it occurs
Occurs from week 4 (day 27) to week 7
Arch 1 = regresses into the maxillary artery
Arch 2 = regresses into the stapedial artery
Arch 3 = forms the left and right common/internal/external carotid arteries
Arch 4 = right forms part of the right subclavian artery, left forms part of the aortic arch
Arch 5 = no arch 5
Arch 6 = right forms part of the right pulmonary artery, left forms the ductus arteriosus
7th segmental arteries = right forms part of the right subclavian artery, left forms the left subclavian artery
Dorsal aorta = right forms part of the right subclavian artery, left forms the descending thoracic aorta
What are the hormones that drive embryonic vessel development (vasculogenesis)
Angiogenic growth factors and repulsive signals
Angiogenic growth factors
- vascular endothelial growth factor
- angiopoietin 1 and 2
Repulsive signals
- plexin/ semaphorin signalling
- ephrin/eph interactions
Between when does vascularization of the yolk sac, chorionic villus and stalk occur?
Day 17-21
When does vasculogenesis begin and where does it begin from
Day 18
From the lateral mesoderm
What is the difference between haemopoiesis, erythropoiesis, myelopoiesis and thrombopoiesis
Haemopoiesis = production of blood cells Erythropoiesis = production of red blood cells Myelopoiesis = production of white blood cells Thrombopoiesis = production of platelets
Give the hormones involved in erythropoiesis, myelopoiesis and thrombopoiesis
Erythropoiesis = erythropoietin (EPO) Myelopoiesis = Granulocyte-macrophage colony-stimulating factor (GM-CSF) Thrombopoiesis = thrombopoietin (TPO)
Give methods used to separate the different types of haemoglobin and explain them
High Performance Liquid Chromatography (HPLC)
-separates the Hb on basis of electrical charge
Hb Electrophoresis
- separates HB on basis of size
- acid and alkaline conditions
What is anaemia
Give some signs and symptoms
A deficiency of Hb
<130g/L in adults males
<110g/L in adult females
Signs
Palor
Tachycardia
Signs relating to underlying cause
Symptoms
Tiredness/lethargy/malaise
Shortness of breath on exertion/ reduced exercise tolerance
Angina & claudication (in older individuals)
Give the causes of anaemia
Results from production failure and increased removal
Production failure
- hypoplastic anaemia (not enough red blood cells produced)
- dyshaemopoietic anaemia (ineffective red blood cells produced)
Increased loss
- blood loss (acute or prolonged)
- haemolytic anaemia (breaking of red blood cell)
What can causes hypoplastic anaemia
Renal failure
Endocrine issues
PRCA
Aplastic anaemia (when body stops producing new blood cells, can affect all blood cell types)- can be inherited, acquired (idiopathic, drugs and chemical or viral)
What is dyhaemopoietic anaemia
Multiple mechanisms e.g caused by chronic disease
Defective Hb synthesis e.g in the globin e.g thalassaemia, in the haem e.g iron deficiency
Defective DNA synthesis e.g folic acid, B12 deficiency
What causes haemolytic anaemia
Intrinsic red blood cell abnormalities
Acquired e.g PNH
Hereditary e.g membrane disorders like Hereditary Spherocytosis enzyme disorders, Pyruvate Kinase deficiency
Extrinsic abnormalities Antibody mediated e.g AIHA Mechanical trauma e.g DIC Infections e.g Malaria Chemicals e.g lead poisoning Sequestration e.g hypersplenism
What is the most common cause of anaemia
Iron deficiency is the most common cause of anaemia
What are the causes of iron deficiency and does it lead to
Causes: Chronic bleeding Poor diet Malabsorption Hookworm
Leads to:
Anaemia
Reduced mean corpuscular Hb (MCH)- amount of Hb in cell
Reduced mean corpuscular volume (MCV) - size of cell
What does reduced mean corpuscular volume mean and what causes it
Reduced mean corpuscular volume (MCV) is the reduced size of the cell
It is caused by iron deficiency
Give some examples of platelet disorders, their causes and effects
Bernard- Soulier Syndrome
Cause - deficiency of GP1b receptor
Effect - so no platelet adhesion
Glanzmanns thrombasthemia
Cause - deficiency of GP2b/GP3a receptors
Effects - no platelet cross-linking or aggregation
Hermansky-Pudlak syndrome
Cause- deficiency of electro dense granules
Effect - no platelet activation or aggregation
What produces erythropoietin
Erythropoietin is produced by the juxtaglomerular cells of the kidney
How would acute blood loss affect anaemia and blood volume
No real effect on anaemia if stopped quickly because same amount of plasma is lost as red blood cells
It is just blood volume that is lost
Give common cell markers of T cells
CD4+ = for the T helper cells - which supress and regulate the immune response CD8+ = for the cytotoxic cells - target and damage infected cells for death
Give a cell marker for B-lymphocyte cell
CD20 - hummoral immunity
What is thalassemia
Thalassemia is when the gene to produce globin chains are absent so ineffective red blood cells produced which leads to anaemia
Alpha thalassemia is a lack of alpha globin chains are more rare because alpha chains are needed for the feotus to survive
Beta thalassemia is a lack of beta globin chains so is more common as usually the feotus would survive to adulthood but then would get anaemia
Which globin chains are present in fetal and adult haemoglobin
Foetus = 2 alpha chains, 2 gamma chains Adults = 2 alpha chains, 2 beta chains
Give the effects of reduced platelet number
- Thrombocytopenia
- > 10 to <140x109/L - increased bleeding
- <10 x 109/L - spontaneous bleeding
Give the effects of increased platelet number
- Thrombocytosis
- Arterial thrombosis
- Venous thrombosis
Give the different types of platelet bleeding
Muco-cutaneous (into skin) = displayed as epitaxis, mennorhagia, prolonged bleeding from cuts, easy bruising and bleeding after haemostatic challenge (surgery, childbirth, tooth extraction and trauma)
Haemophilia (into joints and muscle) = hameophilia type A (1 in 100,000 so common) is caused by a deficiency in factor 8 and is treated with recombinant factor 8, haemophilia type B (1 in 500,000) is caused by a deficiency in factor 9, treated with recombinant factor 9
Give the causes of platelet bleeding
Genetic - haemophilia (x-linked disease)
Liver disease - creates clotting factors and albumin
Vitamin K deficiency - vitamin K is needed to make factors 10, 9, 7 and 2 so without it no clotting and more bleeding
DIC (disseminated intravascular coagulation
Drugs - warfarin and heparin affect coagulation cascade, aspirin and clopidogrel affect platelet function, steroids thin the tissue which causes easy bruising and bleeding
Give the frequency of different blood types in the population
O = 45% A = 40% B = 12% AB = 3%
What are the blood type antigens made from
Carbohydrates
When do anti-bodies to blood type start occuring
At 6 months
How can blood types be determined
With cells and serum
How can rhesus status be determined
With two different reactants
What is the trigger for transfusion in a fit and healthy woman with some blood loss
8g/dl
What is William Harvey famous for
William Harvey 1578 - 1657
Describing the circulation of blood
Describing the heart as a pump and circulation as a closed system
Publishig the De Motu Cordis in 1628
What is Richard Lower famous for
First transfusion in a dog
What is Jean Baptiste Dervy famous for
Transfused 12oz of blood from a sheep into a boy
Resulting deaths from his later transfusions resulted in the transfusion ban of 1670
What is James Blundell famous for
1829
First obstetric transfusion, it was done is a lady who suffered postpartum haemorrage
4 oz was transfused from her husband
What is Karl Landsteiner famous for
1868 - 1948
Discovered the 3 blood groups (A, B and O)
Identified the Rhesus Factor
He won the 1930 Nobel Prize
Give the different types of antibodies
Think IggMEAD
IgG IgM IgE IgA IgD
IgG, IgE IgD are the classic Y shape
IgM is a big wheel shape molecule (5 Ys in a circle)
What class of antibodies react with antigens A and B, and at what temperature do they react optimally
IgM and at cold temperatures (4 degrees)
What class of antibodies react to most immune responses and what temperature do they work optimally at
IgG and at warm temperatures (37 degrees)
Which are the only antibodies that can pass through the placenta wall from mother to fetus
IgG
Give 5 important Rhesus antigens and which chromosome codes for them
C, c, D, E, e
Chromosome 1 codes for the rhesus genes
What is the clinical significance of Rhesus D
Rh D is inherited the child gets one gene (haplotype) from their mother and one from their father
The clinical importance is in Rhesus D negative mother
This is because the father might be rhesus positive and since its dominant, the child becomes rhesus positive
The mother might then recognised the Rd + in the child as foreign and create antibodies to attack the blood cells of the child
This usually does not affect the first pregnancy but the usually the second as the mother has built up a lot of antibodies to quickly attack the second child
This is treated by sensitisation which is when artificial antibodies are given to the mother tricking her immune system to believe she has already produced antibodies and does not need anymore- the sensitisation is done multiple times throughout the pregnancy, Anti- D antibodies are given to the mother
What is sensitisation in terms of Rh D treatment
It is when artificial antibodies (Anti- D antibodies) are given to the mother tricking her immune system to believe she has already produced antibodies and does not need anymore- the sensitisation is done multiple times throughout the pregnancy, Anti- D antibodies are given to the mother
Give the requirements for blood donor selection
Between 17-70 years old
Weight is above 50kg
Hb is above 134g/L in males and 120g/L in females
Pregnant or lactating women are excluded
Donation interval is every 12 weeks (4 months) so can only give 3 donations a year
12 months post risk taking behaviour: peircings, tatoos, paid sex
2 months post live vaccinations
Asked about recent holidays
What would you find on a packed cell transfusion bag
Packed red cells
ABO/Rh group Collection date Product code Expiry date Special testing
At what temperature are platelets stored and why could it be an issue
Platelets are stored at body temperature and this could be an issue because bacteria can thrive at that temperature
At what temperature is fresh frozen plasma stored and what does it contain
Fresh frozen plasma is frozen within 6 hours of arrival and contains coagulation proteins and inhibitors
Stored at below -30 degrees
What is Cryoprecipitate
Rich in fribrinogen
Used in cases like DIC
Give some transcriptions factors involved in embryonic cardiac development and their effects
Overexpression of Nkx2 increases heart size
Inhibiting GATA4 causes cardiac bifida - failure of fusion of endocardial tubes
Preventing Fog-1 prevents cardiac looping
Cascade of (lefty, Pitx2 and Fog-1) transduce cardiac looping
Give the 3 main steps of embryonic cardiac development
Formation of the heart tube
Cardiac looping
Cardiac septation = endocardial cushion formation creating two atrioventricular canals, development of the outflow tract and ventricular septal formation
What percentage of blood is usually in the veins
64%
What percentage of blood usually lies in arteries
7% in the large arteries
8% in the small arteries and arterioles
What percentage of blood is usually in the heart
7%
How is blood flow regulated in the capillaries
Precapillary sphincter
What are the vasa vasorum and where do they lie
Blood vessels that supply the arteries with blood and they lie in the adventitia
Give the modifiable and non-modifiable risk factors for cardiovascular disease also include the psychosocial risk factors
Modifiable risk factors: Obesity High cholesterol Physical inactivity Smoking Stress Diet high in saturated fats and trans fat
Non-modifiable risk factors:
Family history
Diabetes
Psychosocial risk factors: Low socio-economic status Social isolation Work-related stress Depression Panic attacks
Give examples of common causes of failure in management of chronic conditions
- different conditions treated independently (co-morbidities)
- failures in communication between specialists and GP
- difficulty in managing frequent changes in presentation and severity of symptoms
- polypharmacy
Define Evidence based medicine
Evidence based medicine is the conscientious, explicit and judicious use of the best evidence to make decisions on the care of an individual. It integrates the individual clinical expertise, best available clinical evidence with patient values, preferences and beliefs.
5 steps of evidence based practice
Asking focused questions Finding the evidence Critical appraisal Making a decision Evaluating performance
What is the purpose of critical appraisal
To assess the
- validity
- reliability
- applicability
Give some tools for critical appraisal
Critical appraisal skills programme (CASP)
NICE guidelines manual checklists
Cochrane Handbook for systematic reviews for interventions
What is the disability paradox
This is when expectations shift to adjust to their current condition
Their challenged health status leads to a re-evaluation of what is important for life quality
Their lower expectations translate to higher satisfaction
What is intermediate care
This is care that happens after primary care and self care but before (or instead of) large acute hospital care
Examples:
Pre-admissions assessment units, early and supported discharge schemes, community hospitals, domiciliary stroke units or rehabilitation unit
Give examples of intermediate care
Examples:
Pre-admissions assessment units, early and supported discharge schemes, community hospitals, domiciliary stroke units or rehabilitation unit
What is the range for normal serum osmolality
275-295mOsm/Kg
What is the urine osmolality range
50-1400mOsm/Kg (50 being dilute and 1400 being concentration)
What is diabetes Insipidus (differentiate between cranial and nephrogenic)
This is when the body does not respond to ADH
Cranial is when there is an issue with the hypothalamus and the pituitary gland
Nephrogenic is when the kidney itself does not respond to ADH
What is coronary artery disease (CAD)
A disease process that is characterised by the build of atherosclerotic plaque in the coronary arteries
Define Obesity
Accumulation of excess body fat defined by a body mass index greater than 30kg/m (meter square)
What is angiogram
An agiogram (also known as cardiac catheterisation) is a type of xray which uses contrast dye to show an image of the coronary arteries
It shows any narrowing or blockages in the coronary vessels
A catheter is inserted into an artery in the arm or groin and passed up into the heart, the dye (called contrast) will show up on the xray
Blood tests used to asses heart conditions
Cardiac enzyme test (troponin) - help to diagnose a heart attack
Full blood count (FBC) - shows if there is an infection or anaemia due to different cells in the blood
Thyroid function test - shows if an overactive or under active thyroid is present
Lipid profile - measures cholesterol level and other fats in the blood
Liver test - liver enzymes
Clotting screen - to see how quickly the blood clots
BNP (B-type natriuretic peptides) - if elevated can be a sign of heart failure
U and Es test - urea and electrolytes (sodium, potassium, magnesium and calcium) show heart and kidney health
Describe the journey of the right phrenic nerve
The right phrenic nerve arises from nerve C3, 4 and 5 passes through the neck, anterior to the hilum and passes through the diaphragm with the inferior vena cava - supplies sensation and motor innervation to the diaphragm
Some intercostal nerves also supply the periphery of the diaphragm
Where would the vagus nerve be found in the thorax (include the relation to the phenic)
The vagus nerve passes with the common carotid in the neck into the thorax
The right vagus nerve would be found superior and posterior to the hilum of the lung, between the azygous vein and the superior vena cava
The vagus nerve is always posterior to the phrenic nerve
Name the three vessels arising from the arch of the aorta
The brachiocephalic artery, the left common carotid artery and the left subclavian artery
BCS
Which blood vessels feed into the superior vena cava
The right brachiocephalic vein (short), left brachiocephalic vein (long) and the azygous vein.
What is the transverse sinus
The space behind the (aorta and pulmonary artery) and in front of the (superior vena cava, inferior vena cava, 4 pulmonary veins)
This is due to embryonic development when the single aortic artery divides into aorta and pulmonary artery, and the single vein divides into the vena cava and pulmonary veins
It goes across the heart from left to right
Where is the oblique sinus
On the posterior surface of the heart, in “N” of the 4 pulmonary veins
What forms the right edge of the heart on an xray
The superior vena cava, the right atrium and the right brachiocephalic vein
What forms the left edge of the heart on an xray
The left ventricle, the left auricular appendage, the left pulmonary artery, aortic arch, and the left subclavian vein
Which part of the body does the superior vena cava drain from
From the head, neck, upper limbs and some parts of the abdominal walls
Which part of the body does the inferior vena cava drain
Viscera and lower limbs
What is the sulcus terminalis and what is its significance
The bulge where the superior vena cava meets the right atrium is where the vagus nerve and sympathetic nerves synapse with the sino atrial
The sino atrial node sits within the sulcus terminalis (the groove next to the bulge)
In which groove on the heart does the right coronary artery run in
The atrioventricular groove, the tricuspid valve also lies deep to the right coronary artery in this groove
Which groove separates the right and left ventricle? And which vessel runs in this groove
The interventricular groove separates the right and left ventricles and the left anterior descending artery (LAD) runs in this groove
In the heart, when the aorta and pulmonary artery cross over, does the aorta travel in front or behind the pulmonary artery
The aorta travels behind the pulmonary artery
Give the surfaces names of the different sides of the heart
Diaphragmatic (inferior)
Sterno-costal (anterior)
Base (posterior)
Why would a tumour of the left lung be significant
A tumour of the left lung can invade the left recurrent laryngeal nerve and cause paralysis of the muscles of the left vocal cords leading to a hoarse voice
Describe the locations of the left and right recurrent laryngeal nerves
The left recurrent laryngeal nerve branches off from the vagus nerve on the arch of the aorta and passes under the ligamentus arteriosus posterior to pulmonary artery back up the neck posterior to the trachea and anterior to the oesophagus
The left recurrent laryngeal nerve innervates the muscles of the larynx
The right recurrent laryngeal nerve is in the neck not the thorax
What does the left recurrent laryngeal nerve innerveate
The muscles of the larynx
Why are the nerves roots of the phrenic nerve clinically important?
Cervical nerves C3,4 and 5 supply the phrenic nerve and this is clinically important because pain from diaphragm will be felt by the c3,4 and 5 dermatomes which are in shoulder and up the neck, “ pain would be described as felt in the shoulder tip”
What are the main branches of the left common carotid arteries and which organs/tissues does it supply
The left common carotid becomes the:
Left external common carotid: supplies the face and head
Left internal carotid: supplies most of the cerebral hemisphere
The same thing with the right side too
What are the main branches of the left subclavian arteries and which organs/tissues does it supply
The left subclavian artery becomes:
The left vertebral artery: supplies the brainstem, occipital lobe, and the interior temporal lobe
The left thyro-cervical artery: supplies the thyroid gland and the neck
The left axillary artery: supplies the upper limb
The same thing with the right side too
What structures are supplied by the vagus nerve
The pharynx, larynx, heart, lungs, foregut and midgut
What is the surface marking for the apex of the heart
The left midclavicular line at the 5th intercoastal space
How may fibrous pericardium contributeto reduction in ventricular filling
Fibrous pericardium is resistant to stretching so diseases that take space inside of this pericardial sac will result in lower end diastolic volume.
This diseases include muscle hypertrophy, excess fluid
What does primary and secondary prevention mean and give examples in relation to cardiovascular disease
Primary prevention is preventing the disease from happening in the first place e.g vaccinations, eating healthy, exercising regularly, avoid smoking
Secondary prevention is preventing the progression or reoccurrence of the disease
Screening programs
Aspirin in arterial disease.
Beta-blockers and angiotensin-converting enzyme (ACE) inhibitors after myocardial infarction.
Smoking cessation in chronic obstructive pulmonary disease (COPD) and established arterial disease.
Give lifestyle advice to someone at risk of heart disease
No use of tobacco (reduce or quit smoking)
Physical activity - at least 30 minutes, five times a week.
Healthy eating (reduce saturated fats and 5 fruits and veg a day)
Not overweight (a BMI less than 30)
BP <140/90 mm Hg (taking ACE inhibitors or beta blockers)
Total cholesterol <5 mmol/L.
Normal glucose metabolism.
Avoidance of stress.
What is angina
Anginal pain is described as:
constricting discomfort in the front of the chest, or in the neck, shoulders, jaw, or arms
precipitated by physical exertion
relieved by rest or glyceryl trinitrate within about 5 minutes.
The typicality of chest pain can be categorised as follows:
typical angina—all three of the features listed above are present
atypical angina—two of the features listed above are present
non-anginal chest pain—one or none of the features listed above is present.
What is dyspepsia
Dyspepsia symptoms are typically present for 4 weeks or more, and include upper abdominal pain or discomfort, heartburn, nausea, or vomiting. In primary care, dyspepsia is defined more broadly to include people with recurrent epigastric pain or acid regurgitation with or without bloating, nausea, or vomiting.
Causes of dyspepsia include peptic ulceration, oesophagitis, upper-GI cancers, and gastro‑oesophageal reflux disease (GORD). GORD is a chronic condition where gastric juices from the stomach flow up into the oesophagus; heavy alcohol use is a risk factor for GORD. Functional dyspepsia refers to cases when the cause of the symptoms is unknown.
What does the posterior interventricular artery supply
Parts of the interventricular septum
The left and right ventricle
The atrioventricular node (the AV node)
In 90% of hearts, the right coronary artery becomes the posterior interventricular artery
In 30% of hearts, the circumflex artery becomes the posterior interventricular artery
This means in 20% of hearts there are two posterior interventricular arteries
What is the percentage of patency of the fossa ovalis in adults
23%
Where can the posterior interventricular artery be found
On the diaphragmatic surface of the heart in the posterior interventricular groove
Describe the deep surfaces of the atrium, auricular appendages and ventricles
Atrium - smooth muscle walls
Auricular appendages - trabeculated (musculi pectinati)
Ventricle - trabeculated (trabeculae canea)
Where do the coronary arteries originate from
The ascending aorta
Give the branches of the right coronary artery
Right coronary artery gives
The right marginal artery
The posterior interventricular artery (in 90% of hearts)
Give the branches of the left coronary artery
Left coronary artery (left main stem) gives
The left anterior descending artery (LAD) - gives off diagonal arteries
The circumflex artery - gives off the obtuse marginal artery and the posterior interventricular artery (in 30% of hearts)
What is the difference between the sulcus terminalis and the crista terminalis
The sulcus terminalis is the bulge on the outside of the heart while the crista terminalis on the inside of the heart
The crista terminalis lies deep to the sulcus terminalis
The sulcus terminalis is where the vagus and sympathetic nerves synapse with the sino atrial node
Describe the position of the leaflets of the tricuspid valve
Anterior, posterior and one attached to the septum
What is the moderator band
It is called the septomarginal trabeculae
It is a band that runs from the interventricular septum to the anterior wall of the right ventricle, it carries purkinje fibres to the right ventricle
It is not present in the left ventricle
Where is the infundibulum
It is the smooth part before the aortic/ pulmonary valves
Why are the atrioventricular valves different from the semi-lunar valves
The pressure difference between the atrium and ventricle is small so a large orifice is needed. The valves are too big to anchor themselves so need chordea tendoni attached to papillary muscles
The pressure difference between the ventricle and aortic/pulmonary vessels is very large so a small orifice and small valves can be used. The semi-lunar valves are small enough to be anchored by themselves to the vessel wall
How does the purkinje fibres divide at the apex of the heart
One right bundle branch
Two left bundle branch (anterior and posterior)
Where is the best place to listen to a murmur (blood flowing abnormally through a diseased aortic valve)
Where the aorta is closest to the chest wall
What could an infarct in the papillary muscles lead to
Rupture of a papillary muscle
Cannot support valve (is not held in place) so valve is incompetent and allows regurgitation
What is the blood supply for the sino atrial node
In 60% of hearts, it is supplied by the right coronary artery
In 40% of hearts, it is supplied by the left coronary artery
At what phase of the cardiac cycle do the coronary arteries fill and why
During ventricular diastole, this is because blood flows from areas of high pressure to low, and during diastole the pressure in the aorta is high while the pressure is low in the coronary arteries in the myocardium
What is the location of the sino atrial node and the atrioventricular node
The sino atrial node is located in the crista terminalis (deep to the sulcus terminalis)
The atriovetricular node (AV node) is located at the bottom of the interatrial septum
What is the blood supply for the atrioventricular node
The posterior interventricular artery
In 90% of hearts, it is formed from the right coronary artery
In 30% of hearts, it is formed from the circumflex artery
This means in 20% there are two posterior interventricular arteries
What is the name of the valve covering the coronary sinus
The thebesian valve
What is the left ventricle filling
The difference (minus) between the left atrium pressure and the left ventricle diastole pressure
What is the limit of maximal length in cardiac sarcomeres and calculated which length would give only 10% of maximal force
The limit of maximal length (LOMA) in cardiac sarcomeres is 2.2m
Since only 10% of maximal force is produced at 80% of maximal length, 1.76m is the length that produces 10% maximal force
What is length-dependent activation and give an example with cardiac sarcomeres
It is when at a certain length, there is change in cardiac volume and for the cardiac sarcomere this is 85% of maximal length
What can increasing diastolic heart volume lead to
Increased velocity
Increased force of contraction
What is contractlity
This is the state of the heart that allows it to increase its contraction velocity to achieve high pressure when contractility is increased (independent of load)
What is elasticity
This is the myocardial ability to recover its normal shape after the removal of systolic stress
What is compliance
The relationship between the change in stress and the resultant strain (dP/dV)
What is diastolic distensibility
The pressure required to fill the ventricle to the same diastolic volume
How does the pressure-volume loop reflect contractility and compliance
The pressure volume loop reflects contractility in the end systolic pressure volume relationship
The pressure volume loop reflects compliance in the end diastolic pressure volume relationship
What are isometric and isotonic contractions and which are possible in the heart
Isometric contractions can be found during isovolumic contration in the heart
Isotonic contraction is no movement of the cardiac fibres which s impossible in the heart because of the constantly changing volumes
Define primary, secondary and tertiary prevention and give an example of how it is used for cardiovascular disease
Primary prevention refers to the steps taken by an individual to prevent the onset of the disease.
Example - maintaining a healthy lifestyle choice such as balanced diet, avoid smoking and lots of exercise.
Secondary prevention focuses on reducing the impact of the disease by early diagnosis prior to any critical and permanent damage.
Example - beta blockers and calcium channel blockers for blood pressure lowering could reduce the risk of cerebrovascular disease and coronary heart disease. Furthermore statin treatment to lower blood lipids could reduce the risk of atherosclerosis which is the cause for many cardiovascular diseases.
Tertiary prevention is used once long term effects set in, by helping the patients to manage pain, increase life expectancy, and increase the quality of life.
Example - bypass surgery, coronary angioplasty, defibrillators, stents, and pacemakers
Secondary prevention aims to identify a disease within a patient before the onset of symptoms and reduce the impact on the life of the patients.
Explain how platelets form a clot after a plaque rupture
Plaque rupture exposes the contents of the vascular subendothelium
Platelets adhesion
- the platelets attach to collagen through Glycoprotein 1a (GP1a)
- the platelets attach to Von Willebrand factor in the subendothelium through GP1b and GP2b/3a receptors
Platelet activation
- the platelets change shape from smooth to spiculated pseudopodia
- they release their granules contents like ADP and thrombin
- thrombin also acts on PAR4 protein to cause platelet activation
- thromboxane acts on the TPalpha protein to cause platelet activation
Platelet aggregation
- ADP acts P2Y1 protein which causes GP2b/3a receptors to bind to fibrinogen causes cross-linking and platelet aggregation
Platelet amplification
- ADP acts on P2Y12 protein causes amplification
- thrombin acts on the PAR-1 protein which causes the release of calcium ions in the platelets, these calciums inhibit translocase channels and activates scramblase protein, scramblase causes more expresses aminophospholipids on the outer membrane of the platelet, the aminophospholipids cause the assembling of the prothromblase enzyme which converts more prothrombin to thrombin, the thrombin produced causes more amplification
What could glycoprotein 2b/3a be also referred to
Integrin aplha2b/beta3
Explain how aspirin inhibits cyclooxygenase 1 in platelets
Aspirin in low doses inhibits COX 1
Aspirin in high does inhibits COX 1 and 2
Aspirin inhibits COX 1 from converting arachidonic acid to prostaglandin H2 in platelets, this means no thromboxane A2 can be produced. Thromboxane H2 can then not cause platelet aggregation and vasocontriction
Explain how aspirin inhibits cyclooxygenase 1 and 2 in endothelial cells
Aspirin in low doses inhibits COX 1
Aspirin in high does inhibits COX 1 and 2
Aspirin inhibits COX 1 and COX 2 from converting arachidonic acid to prostaglandin H2 in endothelial cells. This causes inhibits production of prostacyclin which usually inhibits platelet aggregation and vasoconstriction
This means high does of aspirin use can actually cause platelet aggregation and vasoconstriction in endothelial cells
What does serotonin do in the platelet aggregation pathway
It is one of the dense granules but causes platelet activation and amplification
What determines capillary flow
Arteriolar resistance
Number of pre-capillary sphincters
What aids venous return
Venous valves aid venous return against gravity Skeletal muscle (respiratory pump) aids venous return Sympathetic stimulation mediates vasoconstriction which aids venous return against venous pressure
What aids the unidirectional flow in lymphatics
Lymphatic valves
Smooth muscle in lymphatic vessels
Skeletal muscle pump (respiratory pump)
Give two laws that govern flow
Ohm’s law - flow = pressure gradient divided by resistance
Poiseuille’s equation - flow = radius to the power of 4
What is mean arterial pressure equal to
Mean arterial pressure (MAP) = cardiac output x total peripheral resistance = diastolic pressure x 1/3 pulse pressure = blood pressure
Why is diastolic pressure not zero
Aortic valve
Aortic elasticity
What is autoregulation
The intrinsic ability of an organ to maintain flow despite perfusion pressure changes
What is the autoregulation usually like in the renal/cerebral/coronary/subcutaneous/skeletal muscle
Excellent in renal/ cerebral and coronary
Poor in subcutaneous
Average in skeletal muscle
Give some vasoconstrictors and vasodilators of blood vessels
Vasoconstriction
Endothelium-1
Internal blood pressure
Vasodilation Hypoxia Endothelium derived relaxing factor (which is the same as nitric oxide) Prostacyclin Bradykinin Adenosine K+, CO2, H+ Tissue breakdown products
How is nitric oxide created in the endothelium
L-arginine is converted to nitric oxide by nitric oxide synthetase
Where are the primary baroreceptors found
The carotid sinus and the aortic arch
Where are the secondary baroreceptors found
The myocardium, the pulmonary vessels and the veins
Give the afferent nerve for baroreceptors
Glossopharyngeal nerve
Give the efferent nerves for baroreceptors
Vagus nerve and sympathetic nerves
What causes short term and long term changes in blood pressure
Baroreceptors cause short term change (minute to minute change)
Blood volume causes long term change
What does stimulation of the anterior hypothalamus cause
Decrease in blood pressure
Decrease in heart rate
What does stimulation of posterolateral hypothalamus cause
Increase in blood pressure
Increased in heart rate
How does the medulla use chemoreceptors to cause change in blood pressure
Chemoreceptors sense high PaCO2 and low pH in the blood and cause vasoconstriction of vessels increasing total peripheral resistance and increasing blood pressure
What causes neuro-cardiogenic syncope and how is treated
Fainting (also called neuro-cardiogenic syncope) is caused by emotion, heat, standing to long and dehydration which causes a fall in heart rate and venous pooling which causes a fall in cardiac output
Treatment is laying supine while elevating limbs to aid venous return
During blood loss, how is blood pressure maintained
Blood loss triggers local vasoconstriction
-increased heart rate to try to maintain cardiac output and blood pressure
In the long term, it leads to shock from low blood pressure and organ hypoperfusion
Treatment is rapid volume replacement
What causes orthostatic hypotension and how is it treated
It is caused by standing too quickly and for too long, dehydration and a hot room which cause decreased blood pressure and venous pooling causing reduced cardiac output
Treatment is laying supine and elevating limbs to aid venous return
What causes POTS (postural orthostatic tachycardiac syndrome)
Caused by an excessive tachycardiac response to standing
Not well understood
Heart rate is usually below 40 beats per minute and blood pressure is usually fine
Give circulating hormonal factors that affect vasoconstriction and vasodilation
Vasoconstrictors
Epinerphrine - when it binds to alpha receptors
Angiotensin 2
Vasopressin (ADH)
Vasodilators
Epinerphrine - when it binds to beta receptors
Atrial natriuretic peptide
What is the oxygen saturation in the coronary veins, how does this compare to other veins and why
Oxygen saturation is lower in the coronary veins compared to other veins and this is because of higher oxygen extraction by heart muscles
It is usually 35% oxygen saturation
Which coronary artery supplies the inferior aspect of the heart
The right coronary artery
Where are coagulation factors and fibrinogen synthesised
The liver
What is responsible for the apex beat that can be palpated in the midclavicular line at the 5th intercostal space
The left ventricle
What cleaves fibrinogen into fibrin
Thrombin
What maintains systolic and diastolic blood pressure by preventing backflow of blood into the left ventricle
The aortic valve
What prevents high pressures developing in the jugular vein during ventricular systole
The tricuspid valve
On an ECG, what represents ventricular repolarisation
The T wave
On an ECG, what should have a duration between 120 to 200msec (0.12-0.2sec) and what does it represent
The PR interval
It represents the electrical impulse travelling from the av node to the ventricles
On an ECG, what leads asses the electrical activity of the lateral myocardial territory
Lead 1, AvL, V5 and V6
On an ECG, compared to the anterior and inferior leads, which lead usually gives inverted complexes
AvR
On an ECG, what may be abnormally elevated during an acute injury/infarction of a substantial myocardial territory
ST segment
On an ECG, what represents atrial depolarisation
The P wave
On an ECG, how would you know a sinus rythmn is present
P waves are present and they are followed by a QRS complex
It just means the sino atrial node is giving the electrical impulses
On an ECG, what represents ventricular depolarisation and should be less than 120 msecs in duration
The QRS complex
How long is the duration of the PR interval
120 - 200 msecs
How long is the duration of the QRS complex
200 msecs or less
Which lead(s) on an ECG give the electrical activity on the septal aspect of the heart
V1
Which lead(s) on an ECG give the electrical activity on the anterior aspect of the heart
V2, V3 and V4
Which lead(s) on an ECG give the electrical activity on the inferior aspect of the heart
Lead 2, lead 3, AvR and AvF
Where does the thoracic duct and azygous vein lie in relation to the oesophagus
The thoracic duct lie deep to the oesophagus and the fascia under the oesophagus, just on top of the descending aorta
The azygous vein lies deep to the oesophagus between the descending aorta and the vertebral column
Where does the thoracic duct lead into
Tbc
What are contained within the ganglia of the sympathetic chain
Cell bodies
They are usually connected by axons and dendrites
Where do the sympathetic nerves arise from
T1 to L2
What are the rami communicantes
The white rami communicates which are presynaptic neurones and are myelinated so appear white, they join the sympathetic chain
Post-synaptic neurones are unmyelinated and appear gray
Where are the nodules of Arantius found and what are they
They are found on the cusps of the aortic valve, they are basically little nodules that develop from thickening of the edges of the 3 cusps of the aortic valve continually meeting
Give the histology of the pericardium
Simple squamous epithelium
It is just one layer of cells
What are the weibel-palade bodies and where are they found
The weibel-palade bodies are found in all endothelial cells and are molecules used for storage
Give some areas in the body that do not contain lymphatics
Cartilage, the eye and bone marrow
Which category do coronary arteries belong to: elastic arteries, muscular arteries or arterioles
Muscular arteries
Do the sino atrial node myocytes have intecalated discs yes or no?
No they do not
Define is cardiac output and explain how each variables contributes to it
Cardiac output is the amount of blood ejected by the heart one minute (about 5.7 litres per minute)
Stroke volume is the amount of blood ejected by the left ventricle per contraction
Factors that affect cardiac output
Preload (affects stroke volume) = this is blood load present in the left ventricle before contraction - more preload causes more stroke volume
Afterload (affects stroke volume) = this is pressure that the ventricle needs to overcome to push blood into the aorta - if too high can cause lower cardiac output
Parasympathetic stimulation (affects heart rate) = negatively chronotropic, vagus nerve, acetylcholine binds to muscarinic receptors
Sympathetic stimulation (affects heart rate) = positive chronotropic, postganglion fibres, release of adrenaline and noradrenaline
What factors affect blood pressure and how does this relate to cardiac output?
Blood pressure is the pressure of blood within and against the arteries
- highest in systole (100-150mmHg)
- Lowest in diastole (60-90mmHg) doesnt go to zero because of the aortic valve and aortic elasticity (recoil)
- Measured with a sphygmomanometer and the brachial artery
Blood pressure = cardiac output x total peripheral resistance
Total peripheral resistance is an average of the total arteriole resistance because they are the principal source of resistance to vascular flow
Pulse pressure = systolic pressure - diastolic pressure
Mean arteriole pressure = diatolic pressure + 1/3 Pulse pressure
Factors that affect blood pressure
- vessel elasticity
- Vasoconstrictors and vasodilators
- Peripheral resistance (blood vessel diameter - smaller diameter causes greater resistance, blood viscosity - high viscosity causes need for more pressure to push and length of blood vessel - longer vessel needs more pressure
Describe Starling’s law of the heart and relate this to heart failure.
Starling’s law of the heart (1918) states that within physiological limits, the larger the volume of the heart, the greater the energy of contraction and amount of chemical change at each contraction
In normal heart, increased left ventricular end diastolic volume in the ventricle would trigger a stronger contraction however in a disease heart, the mechanism fails resulting in the heart being unable to pump blood at a sufficient pressure to meet the body’s needs
This is possible due to the elastic recoil properties of the titin
Mr Clarke’s systoms
His initial heart attack caused no blood supply to the myocyte (hypoxia) so some myocytes died weakening the myocardium
- the myocardium can no longer pump at the sufficient pressure to maintain blood flow to meet the body’s needs (feeling exhausted especially with exercise which has a higher oxygen demand)
- there is backflow of blood as the left ventricle cannot fully empty so the pulmonary veins cannot fully empty, this leads to pulmonary oedema (shortness of breath)
- The right side of the heart cannot also fully empty causing decreased venous flow in the vena cava causing lower limb oedema (lower limb swelling) this is a sign of right heart failure
- The symptoms indicate congest heart failure
The left ventricular end diastolic volume increases sometimes as a result of heart failure because the left ventricle becomes overstretched and dilated when the Frank Starling mechanism fails.
The left ventricular end diastolic volume decreases sometimes as a result of high blood pressure because the heart muscle hypertrophies (cardiac hypertrophy) so can give stronger contractions temporarily although it fails eventually as it does not receive adequate blood supply
Describe the cardiac cycle in terms of atrial, ventricular and aortic pressures. When is the myocardium perfused in a normal person?
The myocardium is perfused during ventricular diastole as pressure moves from high to low, aortic pressure is high while pressure in the coronary arteries in the myocardium is low
Left ventricle systole (left ventricle contraction)
- wave of depolarisation arrives at ventricle
- Causes release of calcium ions (causes R peak on ECG) which act on contractile proteins
- left ventricle pressure becomes greater than left atrium pressure
Isovolumic contraction - The mitral valve closes (this is the first heart sound)
- The heart is contracting while both valves are closed
Maximum ejection - left ventricle pressure rises above pressure in the aorta
- aortic valve opens
- Blood is ejected into the aorta
Left ventricular diastole (left ventricle relaxation)
Start of left ventricle relaxation and reduced ejection - left ventricle pressure peak decreases
- Phosphorylation of the phospholambdan causes reuptake of calcium ions back into the sarcoplasmic reticulum (phospholambdan usually inhibit the SERca2+ pump from reuptaking the calcium into the sarcoplasmic reticulum, by phosphorylating the phospholambdan, it stops inhibiting the SERca2+)
- Left ventricle relaxes
Isovolumic relaxation - the left ventricle pressure decreases below the pressure in the aorta
- backflow of blood into sinus behind aortic valve cusps causes the aortic valve to close
- Aortic valve closes (this is the second heart sound)
- Both valves are closed as the left ventricle relaxes
- The left atrium fills during this period
Left ventricle filling
Rapid left ventricle filling and left ventricle suction - left ventricle pressure falls below the pressure in the left atrium
- the mitral valve opens
- Blood passively flows from the atrium into the left ventricle
Diastasis (slowing of left ventricle filling) - pressure in the left ventricle starts to rise and becomes equal with the pressure in the left atrium so filling temporarily stops
Atrial Systole (atrial booster) - atrium contracts pushing blood into the left ventricle
Describe the coronary circulation of the heart.
Right and left coronary arteries arising from the aortic sinus (behind the cusp of the aortic valve)
Right coronary artery arises from the anterior aortic sinus
Left coronary artery arises from the posterior aortic sinus
Right coronary artery branches off to give right marginal artery, it becomes the posterior interventricular artery in 90% of hearts
Left coronary artery (left main stem) branches off to give the circumflex artery and the left anterior descending artery
The left anterior descending artery (also called the widow maker) gives off the diagonal branches
The circumflex artery gives off the obtuse marginal artery, it also goes on to become the posterior interventricular artery in 30% of hearts
The Great cardiac vein
Runs alongside the left anterior descending artery but upwards and empties into the coronary sinus (also merges with it) - it empties blood from the left ventricle
- the valve of thebesius (also called the valve of Vieussens) and
- The thebesian vein (also called the vein of Marshall, and foramina venarum minimarum)
Both mark where the great cardiac vein becomes the coronary sinus
The anterolateral vein (also called the posterior cardiac vein) also drains the left ventricle and merges (also empties) into the great cardiac vein
The Middle Cardiac Vein
- it runs in the posterior interventricular groove alongside the posterior interventricular artery
- Merges with the coronary sinus or directly in the right atrium
The Small Cardiac Vein
- Drains the right ventricular wall and drains into the coronary sinus
- Other veins such as the anterior cardiac vein drain into the right atrium
The Thebesian veins drain the left atrium into the coronary sinus
The Coronary sinus drain about 85% of coronary blood
The coronary sinus sits behind the atrioventricular node so electrical impulse can be passed from it across the A.V node
What are the consequences of (a) an occlusion of the LAD and (b) an occlusion of right coronary artery, in terms of the territory affected, symptoms and effects on conduction.
An occlusion in the left anterior descending artery (LAD)
Territory affected;
- the left ventricle
- right ventricle
- interventricular septum and the bundle of HIS
Symptoms;
- Shortness of breath
- Weakness
- Pain that radiates in the arm, shoulder, neck
- Heaviness
- Tightness or pressure in the chest area
Effect on conduction;
- Bundle of HIS is within interventricular septum
- So no blood supply can lead to death of conducting system
- death in the respective branch is called left or right bundle branch block
An occlusion of the right coronary artery
Territory affected;
- right atrium
- Right ventricle
- Sinoatrial node (in 60% of hearts)
- Atrioventricular node (in 90% of hearts)
- Some parts of the interventricular septum
Symptoms;
- chest pain, pressure or tightness
- Palpitations (skipped beats, irregular heartbeats)
- Dizziness
- Nausea
- Shortness of breath
- Fatigue
- Pain in arm
Effect on conduction
- death of myocardium at the sino atrial and atriovenicular nodes
- Arrhythmias
An occlusion the circumflex artery Territory affected; - The atrioventricular node in 30% of hearts - The sino atrial node in 40% of hearts Symptoms; - Shortess of breath - Fatigue - Weakness - Chest pain, pressure or tightness Effects on conduction; - death of myocardium at sino atrial and atrioventricular nodes - Arrhythmias
Which nerve innervates the pericardium
The phrenic nerve
What is the effect of parasympathetic nerves on blood vessels
There is no parasympathetic nerve innevation on the blood vessels
If the end disatolic volume is 120ml, what would the end systolic volume be and why?
The end systolic volume would be 50ml because the stroke volume is usually about 70mls
What is increase in the left end diastolic pressure a sign of
Left heart failure
Increase in which pressure would signify mitral valve stenosis
Left end atrial systolic pressure
What is the function of the ductus arteriosus
To shunt blood from the pulmonary artery to the aorta bypassing the foetal lungs
Pulmonary oedema in the presence of normal venous pressure is a sign of
Left heart failure
Severe pulmonary hypertension is likely to cause
Right heart failure
Right ventricle will struggle to overcome pressure so will fail
Shortness of breath, peripheral oedema and ascites are sign of
Biventricular failure
Shortness of breath - pulmonary oedema so left heart failure
Peripheral oedema and ascites - systemic oedema so right heart failure
So both fail
Most frequent cardiac cause of clubbing
Ventricular septal defect (right to left shunt) e.g Eisenmenger’s syndrome
For a normal heart at 72 beats per minute, how long is the cardiac cycle
- 8 seconds
- 3 seconds for systole (ventricular contraction and blood ejection)
- 5 seconds for diastole (ventricular relaxing and filling)
What is active hyperemia
Increase in blood flow due to increase in metabolic activity
What is reactive hyperemia
This is increase in blood flow to an organ that had an occlusion of blood vessel which has now been unblocked
What are the neural inputs that control blood pressure
The pressor region in the medulla increases blood pressure by increasing sympathetic innervation, causing vasoconstriction, increased heart rate and stroke volume (so increased cardiac output), increased contractility (increased force of contraction)
The depressor region in the medulla decreases blood pressure by increasing parasympathetic innervation, causing vasodilation through the vagus nerve
What does the ectoderm give rise to
Central nervous system
Peripheral nervous system
Epidermis of the skin, hair and nails
Pituitary gland, mammary gland and sweat glands
Enamel of teeth
Sensory epithelium of the nose, ear and eye
What does the paraxial mesoderm give rise to
The somites
- myotomes (muscle tissue)
- sclerotomes (cartilage and bone)
- dermatomes (dermis of the skin)
What does intermediate plate mesoderm give rise to
The urogenital system - the kidneys, gonads and their ducts
What does the lateral mesoderm give rise to
It divides into two layers
- the somatic (parietal)
- the splanchnic (visceral)
Somatic gives rise to the future body wall
Splanchnic gives rise to the
- circulatory system
- connective tissue for glands
- muscle, connective tissue and peritoneal components for the gut wall
What does endoderm give rise to
- Epithelial lining of the auditory tube and tympanic cavity
- parenchyma of the thyroid gland, parathyroid gland, liver and pancreas
- the epithelial lining of the gastrointestinal tract, respiratory tract and urinary bladder
At birth, what do the umbilical veins become and what was its purpose in the foetus
The ligamentum teres
At birth, what do the umbilical arteries become and what was its purpose in the foetus
The medial umbilical ligament
At birth, what do the ductus venosum become and what was its purpose in the foetus
The ligamentum venosum
What is the effect of low dose aspirin and high dose aspirin on the platelet
- aspirin exerts an antithrombotic effect by inhibiting platelet function by the acetylation of the platelet cyclo-oxygenase which is the enzyme responsible for the first step in the formation of prostaglandins which are pre-cursor of prostacyclin
- aspirin also prevents the formation of both thromboxane A2 which is involved in the formation of a clot as well as prostacyclin which prevents clot formation
- low dose aspirin 75mg once a day will abolish the synthesis of thromboxane A2 without significant impairment of prostacyclin so causes reduced platelet induced clotting
- high dose aspirin 300mg will inhibit both pathways so the effect is decreased platelet induced clotting and decreased prevention of clotting
What would be the consequences of missing a dose of warfarin and how would this affect the risk/benefit ratio of taking warfarin
- a missed dose of warfarin will result in blood clotting returning to normal levels usually within a 2 to 5 day period
- this will reduce the ability of warfarin to prevent chance of a stroke (benefit)
- it will also reduce the side effects of warfarin which is bleeding (risk)
What would be the risk of accidentally taking a double dose of warfarin and how will it affect the risk/benefit of taking warfarin
- accidentally taking a double dose of warfarin will cause high reduction in the ability of blood to clot which can lead to uncontrolled bleeding
- no additional increased benefit as opposed to taking a normal single dose
- risk of uncontrolled bleeding
Define is cardiac output and explain how each variables contributes to it.
Cardiac output is the amount of blood ejected by the heart one minute (about 5.7 litres per minute)
Stroke volume is the amount of blood ejected by the left ventricle per contraction
Cardiac output is measured by injecting a tracer into the blood and observing the rate of diffusion in blood, this will measure the rate of blood flow
Stroke volume is measure using an echocardiogram
Cardiac output = Stroke volume x Heart rate
E.g 70 beats per second x 70 ml = 4900
Bradycardia = less than 60 beats per minutes Tachycardia = over 100 beats per minute
Factors that affect cardiac output Contractility Heart rate 70bpm to 100bpm Preload Afterload
Preload (affects stroke volume) = this is blood load present in the left ventricle before contraction - more preload causes more stroke volume Afterload (affects stroke volume) = this is pressure that the ventricle needs to overcome to push blood into the aorta - if too high can cause lower cardiac output Parasympathetic stimulation (affects heart rate) = negatively chronotropic, vagus nerve, acetylcholine binds to muscarinic receptors Sympathetic stimulation (affects heart rate) = positive chronotropic, postganglion fibres, release of adrenaline and noradrenaline
Define respiratory failure. Define type 1 respiratory failure and its causes. Define type 2 respiratory failure and its causes.
Respiratory failure is when not enough blood is passing from your lungs into the blood or when not enough carbon dioxide is not being removed from the blood
Type 1 respiratory failure is cause by low oxygen in the blood (hypoxemia) and normal or low CO2 (hypocapnia)
PaO2 < 8Kpa
PaCO2 < 6Kpa
Causes of type 1 respiratory failure are;
- Pulmonary oedema
- Pnuemonia
- Acute respiratory distress syndrome (ARDS)
- Chronic pulmonary fibrosis alveolitis
- V/Q mismatch due to alveoli hypoventilation
- High altitude
- Shunt
- Diffusion problem
Type 2 respiratory failure is low blood oxygen (hypoxemia) and high blood CO2 (hypercapnia)
Causes of type 2 respiratory failure are;
- COPD
- Respiratory muscle weakness (Guillian-Barre syndrome)
- inadequate alveoli ventilation due to reduced breathing effort
- Depression of central respiratory centre (heroin overdose)
- Neuromuscular problems
What is the smallest muscle in the body
-stapedius muscle
What is the largest muscle in the body
-gluteus maximus
What is the strongest muscle in the body
-masseter muscle
What is a motor unit
-a single alpha motor neurone and all the muscles it supplies
What is a motor pool
-all the lower motor neurones that innervates a single muscle
Where are golgi tendons organs found and what innervates them
- golgi tendon organs are found in the tendon (connect bone to muscle)
- type 1b afferent neurones carry sensory information of amount of tension of muscle away
What do muscle spindles do and what is their innervation
- sense stretch in a muscle
- type 1a afferent neurones
What is the vertebral nerve root of the muscle spindle of biceps
C5 – Biceps
C6 – Biceps, Brachioradialis
What is the vertebral nerve root of the muscle spindle of the triceps
C7 – Triceps
What is the vertebral nerve root of the muscle spindle of the patella
L4 – Patellar (knee jerk)
What is the vertebral nerve root of the muscle spindle of the achilles
S1 – Achilles (ankle jerk)
What is anaemia
-deficiency of anaemia
What measurements in an adult male and females would be classed as anaemic
<130g/L in an adult male
<110g/L in an adult female
How do central venous pressure changes and the total peripheral resistance contribute to cardiac output
- central venous pressure changes result in a change to the diastolic filling pressure
- total peripheral resistance/arterial resistance dictates how easy it is for the heart to expel blood
