Case 2 Flashcards
Pathogenesis
The way a disease develops
Syncope
Fainting or passing out caused by the temporary drop in the amount of blood that flows to the brain
Epidermis
The outermost layer of skin tat acts as a barrier to the outside world
parasympathetic innervation
Slowing of the heart rate by the vagus nerve
Atrophy
Decrease in size and number of cells within a tissue or organ
Ischaemia
Reduction in blood flow to a specific organ or tissue
Hypertrophy
A large increase in cell size to increase tissue or organ size
Hyperplasia
A large increase in cell number to increase the tissue or organ size
Metaplasia
a reversible change in which a differentiated cell type is exchanged for another
Mesenchymal Stem cells
stem cells found in the connective tissue
Hypoxia
Reduced oxygen delivery to the tissues
Hypoxaemia
reduced p.p of oxygen in the blood
What are the requirements of a cell to function properly
Internal Homeostasis Constant Energy Supply Controlled cell division Intact Plasma membrane Safe and effective function of cellular activities Genomic integrity
What restricts a cell from functioning properly
Failure of membrane functional integrity (Damage to ion pumps, bacterial toxins) Membrane damage (free radicals) Blockage of metabolic pathways (interruption of proteins synthesis, respiratory poisons, hormone factor lack) DNA damage or loss (Ionising radiation, chemo, free radicals) Mechanical disruption (Trauma, Osmotic pressure) Energy failure (Oxygen or glucose lack, mitochondrial failure)
What are the consequences of anaerobic respiration in a cell
This results in a build up of acid through metabolic acidosis that denatures proteins
Free Radicals
Chemical radicals characterised by a single unpaired electron in the outer shell and are highly reactive
hat happens in a paracetamol overdose
Paracetamol contains free radicals that are usually removed but in this case damage hepatocytes (cells in the liver) and can cause chemical hepatitis
Necrosis
the pathological cell or tissue death in a living organism resulting in an inflammatory response
Coagulative necrosis
Cell death caused by ischaemia in any organ except the brain
infarction
Obstruction of the blood to an organ or tissue and resulting in localised cell death of that tissue
Liquefactive necrosis
Where necrotic tissue liquefies and hydrolytic enzymes leak from the dead cells
Gangrene
Necrosis when there is visible decay of tissue
Fibrinoid necrosis
When small blood vessels are under extreme pressure that results in necrosis of the muscle wall and seepage of plasma into these wall deposits
Fat necrosis
occurs in the pancreatitis release of lipases or in the breast due to direct trauma to adipose tissues
Apoptosis
The falling off of cells- doesn’t produce an inflammatory response
pyknosis
The shrinkage of the nucleus in a necrotic cell
Karyorrhexis
The fragmentation of nuclear material
Dysplasia
Increased cell proliferation, abnormal morphology and decreased differentiation
Dystrophic calcification
The calcification of necrotic or degenerative cells anywhere in the body
Metastatic calcification
The deposition of calcium in otherwise healthy tissues due to elevated levels of calcium
isovolumetric contraction
An increase in pressure with no change of volume
What ion initiates an impact in cardiac myocytes?
An influx of Ca2+
What ion movement occurs on the downward slope of an action potential in a myocardial cell
The closure of Ca 2+ alongside a delayed release of K+ ions
What happens between action potentials in myocardial cells
There is an influx of Na+ to pacemaker cells
The Ca2+ channels recover from activation
What is different in the shape of an action potential in a ventricular myocyte
the downwards slope has a bump in it where there are Ca2+ channels opening to maintain the action potential despite an efflux of K+ and Na+ from the myocytes
What effect does the sympathetic nervous system have on heart rate
Increases heart rate by releasing noradrenaline
What effect does the parasympathetic nervous system have and why?
It releases Ach which decreases the opening of Na+ channels and increases K+ channels so more K+ leaves the cell whilst less Na+ enters
This hyperpolarises the membrane and results in longer refractory periods
What is the parasympathetic nerve of the heart and how does it affect heart rate?
Vagus nerve- slows it down
Venous return
The volume of blood returning to the heart
Cardiac Output
The volume of blood pumped per minute- average around 5L
Preload
The degree of stretch as a result of the ventricles filling up with blood
Ejection fraction
The percentage of blood that is pumped in comparison to the initial preload
What changes occur in the heart in a response to heavy exercise
Increased cardiac output
Increased atrial booster pump action to increase venous return by more forceful atria contraction and a shorter diastole period
Increased ventricular suction
increased myocardial contractility and sympathetic response to increase HR
What are the good lipids- HDL or LDL
HDL
What is Starling’s law of the heart
The initial fibre length in diastole is proportional to the force of contraction
More venous return means higher end diastolic volume
So the muscle must stretch and increase contractility in order to counter this
What controls homeometric (extrinsic) factors of the heart and how
The sympathetic nervous system- by increasing the contractility of the heart without increasing fibre length through increasing Ca2+ conc.
Infarction
An insufficient blood supply carrying oxygen and metabolic needs leading to cell of tissue necrosis
Atheroma
A fatty deposit of the inner lining of the blood vessel wall and can cause an ischaemia
thrombosis
a local clot formation as a result of a thrombus
embolus
A local clot being carried elsewhere in the body
Spasms
Contractions of the muscle within blood vessels
What makes tissues more susceptible to ischaemias?
Previous damage
a single blood supply source
Brain and heart tissues more susceptible
How can non-vascular ischaemias occur
a decrease in deoxygenated blood flow from hypotension, carbaminohaemoglobin or anaemia
Or increased tissue demand
What are myocardial infarctions
A sudden rupture of fatty deposits within the coronary arteries
How can an blocking of the coronary arteries result in myocardial problems
Usually through an atheroma
Less blood therefore less ATP and acidic build up
Fewer Na+ and Ca2+ move out so less water moves out with them and cell oedema can occur
necrosis begins to occur and rapid action needs to be taken to reverse this process
If not reversed the cells are replaced with scar tissue which is much less adapted to it’s function and structually weaker
Build up of lactate and serotonin activates pain receptors in the chest
After an episode can create stunned myocardium that doesn’t contract as well but will recover if a small enough area
Modifiable risk factors of ischaemic heart disease
Smoking Diet Reduced physical activity Overweight/obesity High blood pressure High cholesterol levels Excessive alcohol consumption Excessive stree
Non-modifiable risk factors of ischaemic heart disease
Increasing age Gender- male (prior to age 60) Ethnicity (South Asians) Family history Social deprivation Type 2 diabetes
chronic ischaemic heart disease
slow progressing heart disease due to the atherosclerosis of arteries over time
Angina is a symptom
Acute coronary syndrome
Rapid plaque distribution that leads to occlusion of the coronary arteries
Stable angina
The most common presentation of angina
narrowed coronary arteries due to atherosclerotic plaques
the heart doesn’t receive enough oxygen during exercise to match the workload
there is then a build up of metabolites that leads to chest pain that is gripping in nature and may radiate to the arms or jaw
breathlessness alongside palpitations may occur
normally relieved by rest or nitroglycerides
Variant angina
More often in females than males
Spasm of the coronary arteries
can occur without provocation and results in the heart not getting enough blood, even at rest
there is then a build up of metabolites that leads to chest pain that is gripping in nature and may radiate to the arms or jaw
breathlessness alongside palpitations may occur
silent angina
same pathophysiology as other forms of angina except there is no chest pain or symptoms
possibly as a result of low pain levels or damaged nerves
How is angina managed and treated?
Lifestyle modifications such as stopping smoking, exercising and eating healthy
taking medications that dilate vessels, slow heart rate or reduce heart contractility
A stent or bypass graft can surgically deal with it
Acute coronary syndrome
An umbrella term for unstable angina, Non-ST elevation myocardial infarctions and ST elevation myocardial infarctions
they are all caused by acute disruption of coronary plaque that leads to sudden artery occlusion via platelet aggression
Which acute coronary artery syndrome has complete occlusion?
STEMIs
what are the symptoms of acute coronary syndrome
Central chest pain, dyspnoea and nausea although not all have chest pain and silent MIs may occur
they may also present with pre-snycope and may look pale and clammy
What would the blood marker of troponin T show in the coronary arteries during acute coronary syndrome?
there would be a significant rise for STEMIs and NSTEMIs but not unstable angina as there is no myocardial necrosis
What would an ECG show for a STEMI?
an ST elevation
What is immediate management for acute coronary syndrome?
Oxygen, a vasodilator and analgesia
How can you manage acute coronary syndrome in the long term?
Lifestyle changes and medications in a similar way to angina
What is the acronym for the complications that need to be addressed following an MI?
D eath A rrhythmias R upture of ventricular septum T amponade-fluid accumulation H eart failure- damage or necrosis of muscle
V alve disease- mitral regurgitation A neurysm of the ventricle D Dressler's syndrome (percarditis) Thrombo E mbolism- mural thrombus R eccurence
How long is each large square on an ECG?
200ms