Intro to Pathology Flashcards
Causes of disease
Congenital
Acquired
Congenital diseases
Present at birth
Can be genetic e.g. cystic fibrosis or non-genetic e.g thalidomide anomalies
Acquired diseases
Result of environmental factors
What do most diseases arise from
A combo of causes
Multifactorial aetiology
VITAMIN CDEF
Surgical sieve - thought process for a differential diagnosis
Vascular Infl/ infectious Trauma Automimmune Metabolic Iatrogenic/ idiopathic Neoplastic Congenital Drugs/ degenerative diseases Endocrine disorders Functional
Iatrogenic
Relating to illness caused by medical examination or treatment e.g. vomiting and hair loss w/ chemo
Idiopathic
Cause of disease is not known e.g. idiopathic pulmonary fibrosis
Pathogenesis
Mechanism by which disease is caused
Morphology
Form and structural changes
Neoplasm
Abnormal cell growth, can be benign or malignant (cancers)
What does the ectoderm develop into
Skin Neural tissue Adrenal medulla Pituitary gland Eyes Ears
What does the mesoderm develop into
Muscle Bone and cartilage Heart and blood vessels Urogenital system Bone marrow and lymphatic tissue Adrenal cortex
What does the endoderm develop into
Lining of GI and respiratory tracts GI organs (liver, pancreas) Bladder, vagina, urethra Larynx, trachea, lungs Thyroid and parathyroid glands Thymus
Function of epithelium
Protection (skin) Absorptions (GI tract) Surface transport (airways) Secretion (glands) Excretion (kidney) Gas exchange (alveoli)
What do osteoblasts produce
Osteoid - main component of bone
Predominantly made of collagen
Homeostasis
The process by which internal variables are kept within a normal range of values which allows us to maintain a physiological state which is compatible w/ life
-ve feedback
Focuses on bringing back variable change to normal level, preventing an excessive response
+ve feedback
A variable change causes adjustment in the same direction as the initiating event e.g. bleeding, intensifying the response to stimulus until an endpoint is reached – less commonly used
+ve feedback in bleeding
Break/ tear occurs in blood vessel wall \+ve feedback cycle initiated Platelets adhere to site and release chemicals - stimulating the release of more clotting factors Platelet plug is formed Feedback cycle ends when plug is formed
What does a normal cell require to be viable
Protection from environment Adequate nutrition Communication Energy generation Movement Molecular catabolism Renewal of senescent molecules
Why does a normal cell require communication
Extracellular signals determine whether a cell will live or die, whether it remains quiescent or whether it is stimulated to perform a spp function
Catabolism
Breaking doen molecules
Senescent
No longer viable
Peroxisomes
Able to convert long fatty acids to medium sized ones - also generates H2O2 but peroxisome contains peroxidase
Peroxidase
Converts hydrogen peroxide into water and oxygen
How does material arrive at lysosomes
Via 1 of 3 pathways:
Endosome
Phagosome
Proteosome
Endosome
Transports substances in and out of cells
Proteosomes
Organelles which digest unneeded or damaged proteins, releasing peptides after they have been identified by attachment of ubiquitin
What cannot diffuse through the lipid bilayer
Polar molecules >75 Daltons in mass
Ions
Examples of molecules that can passively diffuse through phospholipid bilayer
Oxygen Carbon dioxide Urea Alcohol Steroids
Methods of transporting substances in and out of cells
Carrier or channel proteins Endocytosis Exocytois Phagocytosis Transcytosis
Types of endocytosis
Caveolae- mediated endocytosis
Receptor-mediated endocytosis
Caveolae mediated endocytosis
Involved in regulation transmembrane signalling and cell adhesion by moving receptors
Moves integrins and is responsible for vitamin uptake
Integrins
Molecules which join cells to the surrounding stroma).
Receptor mediated endocytosis
Vesicles form around bigger molecules
These fuse w/ lysosomes, releasing contents
Receptors are then recycled back to the plasma membrane
Transcytosis
Movement of endocytosed vesicles between apical and basolateral components of the cell – how antibodies pass from breast milk through intestinal cells
Main methods of cell communication
Synaptic transmission
Autocrine
Paracrine
Endocrine
Synaptic transmission
Occurs at the neuromuscular junction, where acetylcholine travels from a nerve across the synaptic space to the acetylcholine receptor on the muscle cell
Autocrine signalling
When the cell stimulates itself and this occurs during cell development or to amplify a response, tumours can survive by producing growth factors which act via an autocrine mechanism
Paracrine signalling
Targets cells in immediate vicinity
Involved in generation of new blood vessels e.g. angiogenesis
Also involved in cell motility and tumour metastasis
Which signals do cells respond to
Pathogens Damage to neighbouring cells Contact w/ neighbouring cells Contact w/ extracellular matrix Secreted molecules e.g. growth factors, cytokines and hormones
Receptor mediated signalling
Receptors can be in cell (transcription factors) or on cell surface (transmembrane proteins w/ extracellular domains which bind soluble secreted ligands)
Activated by lipid-soluble ligands e.g Vit D and steroid hormones
What happens after a ligand binds to a cell surface receptor
Ion channel opens - usually at neuromuscular junction
A G-prptein is activated
Tyrosine kinase activation
Latent tran scripting factor activated
Growth factors
Stimulate activity of proteins which are needed for cell survival, growth and division
Promote entry of cells into the cell cycle
Relive blocks on cell cycle progression
Prevent apoptosis
Enhance synthesis of cell components
Function of ecm
Support cell anchorage, polarity and migration
Control cell proliferation via growth factors and integrin signalling
Provides a scaffold for tissue renewal
Creates tissue microenvironments
Important properties of stem cells
Capacity for self-renewal
Asymetric division
Asymmetric cell division
One daughter cell matures, and the other remains a stem cell
Symmetric cell division
Two daughter cells
Occurs in embryonic stem cells and under conditions of stress
Totipotent
Can give rise to all types of differentiated tissues e.g. embryonic stem cells
Adult stem cells
Tissue stem cell
Can only replace cells in the tissue in which they reside
Reside in stem cell niches in many organs
Multipotent stem cells
Found in bone marrow and fat
Give rise to chondrocytes, osteocytes, adipocytes and myocytes
Stem cell niches
Around bone marrow vessels
In the bulge region of the hair follicle
In the limbus of the cornea
In gut crypts
In the canals of Hering of intrahepatic bile ductules in the liver
In the subventricular zone of the brain
