52 - Cellular Adaptations (Myocardial Hypertrophy, Valve Defects) Flashcards
Hypertrophy
Increase in size of cells without increasing cell number Increased production of intracellular structures with an increase in nucleus size and shape
Which cells take the hypertrophy pathway in response to mechanical stress, growth factors, etc?
Permanent cells
Hyperplasia
Increase in cell number Occurs in labile cells
Example of physiological hyperplasia
Proliferative and secretory endometrium
Example of pathological hyperplasia
Parathyroid hyperplasia.
*Appearance of parathyroid hyperplasia
Normal parathyroid is speckled with white, which is fat, In hyperplasia, fat is lost.
Example of pathological mixed hypertrophy and hyperplasia
Grave’s disease (antibody mimics thyroid stimulating hormone)
*Appearance of thyroid in Grave’s disease
Normal thyroid has cuboidal epithelial-bound follicles filled with acellular colloid. This is lost in Grave’s disease. Cuboidal epithelium becomes columnar.
Where does metaplasia often occur?
Junctions between different epithelial cell types.
Common stimulus for metaplasia
Altered environment
Metaplasia
A reversible change in which one adult cell type is replaced with another
Example of physiological metaplasia
Pre-menarche epithelium is mucosal (simple columnar). At onset of menarche, tissues swell and expose mucosa to acidic vaginal environment. Becomes stratified non-keratinising stratified squamous epithelium
Example of pathological metaplasia
Barrett oesophagus. Acid reflux from stomach causes non-keratinising stratified epithelium to become intestinal columnar epithelium with goblet cells.
What triggers metaplasia in Barrett oesophagus?
Bile acid stimulates NF-kB in epithelial cells, causing them to differentiate to intestinal columnar epithelial
Hyperplasia and metaplasia vs neoplasia 1) 2) 3) 4)
1) Hyper/meta are controlled division in response to a stimulus. Neoplasia is uncontrolled that can occur without stimulus. 2) Gene expression in hyper/meta is unchanged. Neo is result of genetic change. 3) Hyper/meta are benign, but can predispose to neo. Neo can be benign or malignant. 4) Hyper and meta can be reversible
When is atrophy irreversible?
When accompanied by cell death or fibrosis
Characteristics of physiological myocardial hypertrophy 1) 2) 3) 4)
1) Growth of ventricle wall in proportion to chamber 2) Increased capillary density 3) No loss of systolic or diastolic function 4) Reversible
Characteristics of pathological myocardial hypertrophy 1) 2) 3) 4)
1) Growth of ventricle wall with reduced or enlarged cavity 2) Reduced function, progression to heart failure 3) Deposition of matrix 4) Does not regress
Patterns of myocardial hypertrophy
1) Concentric - from excessive pressure 2) Eccentric - from excessive volume
Normal left ventricle thickness
Under 15mm
Normal RV thickness
Under 5mm
Normal male and female heart weights
Women over 400g Men over 500g
Microscopic appearance of hypertrophied cardiac muscle 1) 2) 3)
1) Enlarged, rectangular (box-shaped) nuclei 2) Bi-nucleated myocytes 2) Increased connective tissue
Genetic cause of myocardial hypertrophy
Hypertrophic obstructive cardiomyopathy (HOCM)
Nutmeg liver
From high right heart pressure. Blood is pushed back into hepatic veins, which haemorrhage.
Ways to classify valve diseases 1) 2) 3)
1) By pathological process (EG: degenerative, infectious) 2) By result (EG: stenosis, regurgitation) 3) By valve affected (EG: mitral, aortic)
Congenital cause of aortic stenosis
Congenital bicuspid aortic valve. Valve wears out, becomes calcified over time
Example of a mitral valve problem
Myxomatous mitral valve, aka sloppy valve. Causes mitral valve prolapse. Can be related to connective tissue disease
What is acute rheumatic fever? 1) 2) 3)
1) Streptococcus pyogenes infection, typically in children 2) Infection of throat. 3) ~3% develop carditis and arthritis
Rheumatic heart disease
1) Aberrant immune response to strep infection because of molecular mimicry (of cardiac myosin) 2) Causes fibrosis of any valve, multiple valves at once 3) Most common global cause of mitral valve stenosis
Infective endocarditis
When there is a dysfunctional valve and bacteraemia, there is a change of a thrombus forming on valve with bacteria in it - a vegetation.
How does infective endocarditis present?
1) Fever 2) Worsening of, new onset of murmur 3) Symptoms of embolism
How can a bacteraemia leading to infective endocarditis come about?
From dental work, invasive surgery, IV drug use
Name for cardiac failure arising from hypertension
Hypertensive heart disease
Ramipril
ACE inhibitor
