General Pathology Flashcards
Define Pathology
Study of disease
Define disease
abnormality of cell/tissue structure and/or function
complications are known as what
sequelae
what enzymes aids DNA replication
DNA polymerase
what enzyme aids transcription (DNA > RNA)
RNA Polymerase
what are the different types of epithelial cells
squamous glandular and solid organs such as the liver kidney and thyroid
types of connective tissue
fibrous
blood vessels
fat
muscle
bone
cartilage
what are some examples of external environmental stresses
physical factors
chemical factors
infection
nutrition etc.
what are some examples of internal environmental stresses
more or less functional demand
hormones/metabolic
immune response
define atrophy
when there or less cells or they are reduced in size
what is hyperplasia
when there are more cells
what is hypertrophy
when the cells increase in size
what is metaplasia
when the differentiated cells transform into different differentiated cells
what is dysplasia
abnormal growth of the cells
physical agents caused by mechanical trauma in the mechanisms of disease
stricture, adhesions, hernia and criminal
what damage do chemicals and drugs do to cells
damage various cells and organelles and processes such as disrupting the cell membranes (osmotic damage), protein production or folding
this can include:
poisons like cyanide
environmental chemicals such as insecticides
occupational hazards like asbestos
hypoxia
deficiency of oxygen
causes:
- anaemia
- respiratory failure
this disrupts the oxidative respiratory processes in mitochondria in the cell and so decreases ATP
Define Ischaemia
reduction in blood supply to the tissue
cause:
blockage of arterial supply to venous drainage e.g. atherosclerosis
results in:
the depletion of not just oxygen as with hypoxia alone, it also depletes nutrients like glucose
DAMAGE IS MORE RAPID AND SEVERE
What type of sensitivity is anaphylaxis and autoimmune reactions
type 1 hypersensitivity IgE mediated
Type 2: antibodies directed towards antigens on cells
Type 3: antigen-antibody complexes and their deposition
what does damage to mitochondria lead to
disrupted aerobic respiration/ ATP synthesis
what does damage to the cell membrane lead to
disrupted ion concentration especially increases calcium 2+ ions
what does damage to the cytoplasm and ribosomes lead to
Disrupted enzyme and structural protein synthesis and architecture
What does damage to the nucleus lead to
disrupted DNA maintenance and DNA damage
oxidative stress mechanism
oxidative stress is caused by ROS also known as free radicals
This is normally formed in small amounts as a by-product of respiration
however
it can be formed pathologically due to the absorption of radiation. toxic chemicals and hypoxia
individuals who lack antioxidants can also make damage more likely
reversible cell injury: Cloudy swelling
osmotic disturbance, loss od energy-dependant Na pump leads Na influx and build up of intracellular metabolites
reversible cell injury: fatty change
accumulation of lipid vacuoles in cytoplasm caused by disruption of fatty acid metabolism, specially the liver
the mechanism of necrosis
This is caused by injury due to external stimuli and is categorized an uncontrolled cell death which means it is always pathological. The contents of the cell leak due to breakdown of the cell membrane so therefore it often elicits an inflammatory response.
Histological changes:
- Cell swelling can be seen, along with vacuolation and disruption of the membranes of the cell and its organelles which include the mitochondria, lysosomes, and ER.
- You will see the release of cell contents (cell lysis) including the enzymes causing adjacent damage and eliciting acute inflammation
Nuclear changes on histological slides include:
- Nuclear fading
- Nuclear shrinkage
- Nuclear fragmentation
apoptosis mechanisms
APOPTOSIS:
This is often a normal physiological process that is used during development and embryogenesis. However it can be pathological in the case of viral infections however it is always controlled. Due to this the cell contents do not leak as the cell membrane remains intact and therefore does not elicit an inflammatory response.
coagulative necrosis
firm, tissue outline retained
- haemorrhage due to the blockage of venous drainage
- gangrenous: larger areas especially lower leg
colliquituve necrosis
tissue becomes liquid and its structure is lost, this occurs in the infective abscess and cerebral infarct
caseous necrosis
combination of coagulative and colliquitive, appearing “cheese-like” this is classical of granulomatous inflammation especially in TB
fat necrosis
due to action of lipase on fatty tissue
apoptosis morphology
- cell shrinkage
- chromatin condensation which packages up the nucleus
- membranes of cell and mitochondria etc. remain intact so dont cause inflammation
- cytoplasmic blebs form and break off to form apoptotic bodies which are phagocytosed by macrophages
what causes redness at sites of infection
dilation of the small blood vessels
what causes heat during infection
increased blood flow due to the vasodilation and fever
what causes swelling during infection
accumulation of fluid in the extracellular matrix
what causes pain during an infection
stretching of tissue due to oedema, mediators such as bradykinin and serotonin stimulate pain receptors
what is loss of function due to in infection
movement is inhibited by pain, severe swelling can immobilise the inflamed area
what features effect vascular permeability
- contraction of the endothelial cells
- increased inter endothelial spaces
- mediated by histamine, bradykinin and substance P
- endothelial injury in severe injuries
- injury can be caused by neutrophils
- increased transcytosis
how is the acute response terminated
- removal of stimulus
- neutrophils have a short half life
- variation in cytokine stimuli
- neural impulses
- macrophages are activated to perform different functions
how is the acute response terminated
- removal of stimulus
- neutrophils have a short half life
- variation in cytokine stimuli
- neural impulses
- macrophages are activated to perform different functions
examples of cellular derived mediators of inflammation
vasoactive amines (histamines and serotonin)
arachidonic acid metabolites
nitric oxide
cytokines (TNF, IL-1, IL-6 and chemokines)
what are some examples of pals a protein derived mediators of inflammation
complement
coagulation and kinin systems
PCR is used for what
demonstration of large scale quantitative changes in DNA such as clonality in lymphoma
FISH is used for
diagnostic translocations (e.g. Ewings sarcoma) and increased gene copy number (Her2)
What is next generation sequencing used for
broader panels to look for multiple gene mutations in the same specimen (e.g. colorectal cancer for BRAF, NRAS, MSI etc.)
What is next generation sequencing used for
broader panels to look for multiple gene mutations in the same specimen (e.g. colorectal cancer for BRAF, NRAS, MSI etc.)
what is anomaly
defined as any deviation from the expected or average form and/or function which is interpreted as abnormal
major- those with cosmetic or surgical consequences
Minor - those with little impact on the individual well being
what is a malformation
a morphological defect of an organ, or region of the body, resulting from an intrinsically abnormal developmental process
what is an cyanotic congenital heart defect
left to right shunt, this means there is no signs of cyanosis in the early stages but an uncorrected VSD can increase pulmonary resistance leading to the reversal of the shunt and corresponding cyanosis
spina bifida
defect of the neural tube where a portion of the tube fails to develop or close properly
this is known as encephalacele if its towards the caudal end of the tube
what is the definition of a syndrome
multiple anomalies thought to be pathologically related
name some characteristics of Down syndrome
mental retardation
low set ears
abundant neck skin
single palmar crease
intestinal stenosis
hypotonia
umbilical hernia
predisposition to leukemias
gap between first and second toes
congenital heart defects
protruding tongue
epicentral folds and flat facial profile
ectopia
meaning out of place
an abnormal location or position of an organ or a tissue most often occurring congenitally but can occur as a result of injury
ectopia cordis
displacement of the heart outside the body
ectopic thyroid tissue
nodules of mature thyroid tissue located elsewhere in the neck
ectopic pregnancy
implantation occurring in the Fallopian tube rather than in the endometrium
hamartoma
tumour-like malformation composed of mature normal cells in usual location but as a disorganised mass
EXAMPLE:
Peutz-Jeghers Syndrome
- mucocutaneous pigmentation
- Hamartomatous polyposis - jejunum and ileum common sited
Mutation STK11 gene on chromosome 19p13.3
diverticulum
circumscribed pouch/sac caused by herniation of lining mucosa of an organ though defect in muscular coat
examples:
- heckles diverticulum
- sigmoid colon diverticula.diverticular disease
intussusception
invagination of a portion of the intestine at most commonly the ileocaecal valve
what are cellular adaptions to stress
are reversible changes in the number/size/type of cells in response to changes in their environment
what are physiological adaptions to stress
are responses of cells to normal stimulation by hormones or endogenous chemical mediators
what are pathological adaptions to stress
responses to stress that allow cells to modulate their structure/function and avoid (or reduce) injury
benign neoplasm
- a neoplasm that grows without invading adjacent tissue or spreading to distant sites
- usually well-circumscribed due to lack of invasion of surrounding tissues
malignant neoplasm
- invades surrounding normal tissue
- spreads to different sites
- not well circumscribed
- malignant neoplasm (tumour) and cancer are synonyms
dysplasia
abnormality of epithelial cells or melanocytes in surface or lining epithelium
disordered growth in which cells fail to differentiate fully, but are not contained by the basement membrane
arterial thrombus
white thrombus - many platelets, small amounts of fibrin (reflects high flow)
venous thrombus
red thrombus as many fibrin with trapped red cell
venous thrombus
red thrombus as many fibrin with trapped red cell
