P.A.T.H.

Pituitary Adenoma Applies pressure to the optic nerve, causing defects in the visual field Increases intracranial pressure, causing headaches, nausea and vomiting (because of pressure onto chemoreceptor vomiting centre) Growth Hormone Disorders Dwarfism - too little growth hormone, short stature Gigantism - too much growth hormone before puberty, tall stature Acromegaly - too much growth hormone after puberty, tall stature Anti-Diuretic Hormone Disorder Diabetes insipidus - too little ADH causing polyuria due to: Destruction of pituitary gland Impaired function or damage to hypothalamus Sporadic (irregular) defects in ADH synthesis (genetic) Thyroid Gland Disorders Hypothyroidism: cretinism (congenital) or myxoedema (acquired) Hyperthyroidism: Grave's disease, multi-nodular goitre, adenoma of the thyroid, thyroiditis and thyroid storm Goitre: increase in the thyroid gland, mostly commonly being an irregular multinodar goitre , due to Hypothyroidis...

Arthritis is a group of inflammatory diseases of joints with severe causes: Degenerative joint disease from wear and tear over time, i.e. osteoarthritis Autoimmune joint disease where the body makes antibodies against synovial cells in the joint, i.e. rheumatoid arthritis Metabolic, where protein synthesis is inadequate and crystals form, i.e. gouty arthritis Infection within the joint cavity, i.e. septic arthritis Osteoarthritis Degenerative joint disease where cartilage is degenerated. Site: localised or generalised (more than 3 joints), affects weight bearing joints, knee, hip, spine and joints of hands and feet Age: over 50 Cause: primary or secondary, due to trauma, defects of joint structures or inflammatory diseases Characteristics: progressive loss of articular cartilage Risks: age, obesity, occupation (e.g. heavy lifting), crystal deposition and inflammation Symptoms: joint pain increased by night, cold and damp weather and relieved by heat a...

Abnormalities of spinal curvature Kyphosis : excessive outward curvature of the spine, causing hunching of the back Lordosis:  excessive inward curvature of the spine Scoliosis:  abnormal lateral curvature of the spine, congenital or developed from poor posture Fractures Fractures of bones are classified according to the pattern of the break and heal in a predictable manner. Treatment: alignment of the bones back together, immobilisation with plaster/pins, stress relief Closed (simple) fracture: skin is not punctured by bone Open (compound) fracture: ends of broken bone tear through skin Compression fractures: collapse of a vertebrae (most commonly due to osteoporosis, primary tumours or infection) Result: thrombotic or fat embolisms released into ruptured blood vessel → infarction and necrosis, infection (osteomyelitis), impaired fracture healing due to malunion Diagnosis: X-ray, CT and MRI (for spinal fractures when testing spinal cord injury)...

Pancreatitis Pancreatitis can either be acute or chronic. We will mainly talk about acute pancreatitis here. Acute pancreatitis Characteristics: enzymatic necrosis and inflammation of pancreas, increase in pancreatic enzymes in blood and urine Result: acute onset of epigastric pain (worse in supine position, radiates to back), cause and vomiting, abdominal distention due to fluid accumulation, pseudocyst (cyst with fibrous or granulation tissue), systemic organ shock, renal failure, intravascular coagulation, duodenal obstruction Cause: alcohol, gallstones, trauma Pathogenies: amylase, lipase and protease leak out of pancreatic acinus and pancreatic duct, causing a steep rise in amylase and smaller rise in lipase blood levels. Lipase causes fat necrosis and protease causes blood vessel destruction and haemorrhage. Diagnosis: sharp increase amylase, followed by smaller, slower increase in lipase levels Consequences of chronic pancreatitis Pancreatic pseudocys...

What are the tests to identify hepatobiliary function?    1.   Bilirubin Levels Normal serum bilirubin levels: 1.2mg/dL Jaundice serum bilirubin levels: 2.0mg/dL (severe jaundice 30mg/dL)    2.   Liver Enzymes   i. Aminotransferases and aspartate aminotransferase are liberated into the blood whenever liver cells are damaged.  ii. Alkaline phosphatase is the main indicator for biliary obstruction iii. Gamma glutamyl transferase increases as a sensitive indicator of liver abnormality    3.   Plasma Protein   i. Albumin  ii. Coagulative factors iii. Prothrombin Liver Cirrhosis Liver cirrhosis is the necrosis, fibrosis and conversion of the normal liver architecture into abnormal nodules. There are three types of cirrhosis: Post-Necrotic Cirrhosis (follows hepatitis) Biliary Cirrhosis (follows obstruction) Alcoholic Cirrhosis Below is a summary of the stages of alcohol...

Gastritis Inflammation of the gastric mucosa that can be either acute or chronic. Age group: Acute: 40-50 year olds Chronic: over 60 year olds Risks: helicobacter pylori infection, smoking/alcohol abuse/high caffeine, spicy food, aspirin and NSAID use (most common risk) Acute Gastritis Erosion of the surface epithelium where mucous barrier is broken down, exposing cells to the strong acidity of the gut. Healing time: few days (due to high regeneration rate of cells) Symptoms: epigastric pain and hematemesis Chronic Gastritis Produces scarring and involves atrophy of the gastrointestinal mucosa. Characteristics: low no. of secretory cells, progressive and permanent thinning and degeneration of the gastric mucosa, decreased digestion of protein and decreased HCl, lack of intrinsic factor → pernicious anaemia Result: can lead to gastric cancer (2 in 3 chance) Hiatal Hernia A hernia occurs when a portion of an organ pushes up, through or into an o...

An introduction to nuclei... Nuclei of the basal ganglia: Substantia nigra Caudate Putamen Globus pallidus These nuclei are associated with allowed us to develop highly skilled behaviour. Basal ganglia disease: increase or decrease in the motor output of the cortex Parkinson's Disease Cause: unknown, damage to nigral neurons Characteristics: extrapyramidal, progressive movement disorder, chronic degenerative disorder Symptoms: tremor, jerky movements, rigidity, mask-like face, stiff heavy and tired limbs, lead-pipe resistance Akinesia Definition: loss of associated and voluntary movements of all skeletal muscles Symptoms: inability to maintain upright position, saliva dripping, gait step, dementia, depression Huntington's Disease Age group: 30-50 years Cause: degeneration of caudate, putamen and front cerebral cortex due to autosomal dominant trait Characteristics: enlarged lateral ventricle, decrease in Ach and GABA, increase in d...

Stroke or Cerebrovascular Accident Cause: occlusion of cerebral vessels by a thrombus or embolus (mostly ischemic), intracerebral haemorrhage due to ruptured blood vessel, issue external to the CNS Risks: smoking, obesity, hypertension, diabetes, high cholesterol, genetic factors, transient ischaemic attack (mini stroke with quick symptoms that last for several hours, warning sign for major stroke) Symptoms: numbness, weakness or paralysis, sensory deficit, loss of consciousness, severe headache, sudden blurred vision or blindness, slurred speech, unsteadiness, confusion Brain Tumors Gliomas Cause: mostly metastatic and rarely primary tumours Most common type: astrocytoma (cerebrum) Types of astrocytoma: glioblasta multiforme, pilocytic astrocytoma and anaplasic astrocytoma Astrocytoma: glioblasta multiforme Poorly differentiated and fast growing Most common glioma No clearly defined margins Invade locally and spread along white matter pathways Age group: 40...

What is an aneurysm? Aneurysms are an abnormal localised dilation of an artery or vein, most commonly occurring in the aorta. Causes:  congenital weakness in blood vessel, hypertension, atherosclerosis, trauma, syphilis (STI)   1.   Berry Aneurysm Small Spherical dilation of a blood vessel Less than 1.5cm in diameter Common in Circle of Willis   2.   Fusiform Aneurysm Involves entire circumference of the vessel Gradual and progressive dilation of a vessel Up to 20cm in diameter Can occur in entire ascending and transverse portion of the thoracic aorta   3.   Saccular Ranges from 5 to 20cm in diameter Partially or completely filled by thrombi   4.   Dissecting False aneurysm caused by a tear in the intimal layer of the vessel Life-threatening Common in 40-60 years Ascending and descending thoracic aorta What is hypertension? Hypertension is defined as blood pressure that exceeds 140mmHg s...

What is cholesterol? Cholesterol is produced at the liver, but is also consumed when we eat meat and dairy products. In order to test the levels of cholesterol in an individual, a serum lipid test is undergone. The ideal result is less than 5.2mmol/L. When this test is undergone, three types of cholesterol are found in the blood. These are: Triglycerides (0.1-1.9g/L) HDL cholesterol (>0.1mmol/L) LDL cholesterol (<3.2mmol/L) Most of the cholesterol in our system is carried by LDL (low density lipoproteins), with the smaller portion being carried by HDL (high density lipoproteins). HDL is the more favourable transport system, however, as it transports cholesterol to the liver from tissues for catabolism into excretable bile salts. LDL carries cholesterol to cells for the synthesis of cell membranes and steroids, which is not ideal in large quantities. What is atherosclerosis? Atherosclerosis is when there is a build up of plaque in the arteries. Risk increases with ...

Heart Failure Heart failure, unlike coronary artery disease which is a condition in which the blood does receive  enough blood, is characterised by an inability to pump  enough blood to the tissues. It is often referred to as congestive heart failure as fluid begins to accumulate in the tissues, i.e. oedema occurs. It is normally chronic, meaning it develops over a long period of time, and does not have a single cause: Coronary disease High blood pressure Cardiomyopathy Atrial fibrillation Heart valvular problems   1.   Left Heart Failure Causes : mitral stenosis, aortic stenosis, pericarditis, myocardial infarction Characteristics : output of left ventricle becomes less than the amount of blood received from the left side via pulmonary circuit → congested pulmonary circuit ('crackles' when listened to by doctors), systemic blood pressure falls Symptoms : dyspnea, increased respiratory ate, cough, cyanosis (from lack of oxygen), blood tinged...

Angina Angina occurs when the heart muscle does not receive enough blood, i.e. oxygen. It usually means there is a narrowing or partially blocked coronary artery during times of stress or exercise. Characteristics : intense pain, pale, perfuse perspiration, dyspnoea, normal cardiac enzymes, ECG may show some ischemic changes but is not definitive for angina   1.   Stable Angina Most common Chest pain during activity or stress Pain begins slowly and worsens over a few minutes before disappearing Means there is an increased risk of heart attack, but does not guarantee occurrence Requires medical treatment for occlusion within coronary arteries   2.   Unstable Angina Acute chest pain with cardiac hypoxia Warning sign of heart attack Not slow like stable angina, occurs as a severe episode Occurs at any time Myocardial Infarction Myocardial infarction is a result of longterm schema to the myocardium (heart muscle), causing irreversible ce...

Hodgkin's vs Non-Hodgkin's Lymphomas Staging of Hodgkin's and Non-Hodgkin Lymphomas Stage 1: single node or single extra-lymphatic organ Stage 2: 2 or more lymph nodes on same side of diaphragm or limited contiguous (touching at borders) extra-lymphatic organ/tissue Stage 3: both sides of diaphragm, may include extra-lymphatic organ Stage 4: one or more extra-lymphatic organs or tissues with/without lymphatic involvement

Non-Hodgkin Lymphomas Non-hodgkin lymphomas are three times more common than Hodgkin's lymphomas, with increasing incidence. Mostly, they arise in lymphoid tissue, with a small percentage in parenchymal organs. B-lymphocytes are the main cells affected in non-hodgkin lymphomas, with some specific types concerned with T lymphocytes. Non-hodgkin lymphomas have an quick, rapid spread unlike hodgkin's lymphoma and is normally widespread at the time of diagnosis. Characteristics: enlarged non-tender lymph nodes Symptoms: fever, weight loss, malaise, sweating, susceptibility to infection Types of Non-Hodgkin Lymphomas   1.   Diffuse Lymphomas Make up almost half of all non-hodgkin lymphomas Occurs in the elderly Grow in a uniform pattern without any follicles Most form from B cells, but can form from T cells Lymphocytes are large, have large nuclei and have a prominent nucleolus Localised at time of diagnosis Curable with chemotherapy   2.   Foll...

What are lymphomas? Lymphomas are a neoplasm of the lymphoreticular organs. They present as solid nodular tumours usually in the lymph nodes, but sometimes in organs. Lymphoma malignant cells are not detectable in blood, so a biopsy is required for diagnosis. Hodgkin's Lymphomas Hodgkin's lymphomas make up a very small portion of all cancers, and only a slightly larger portion of all the lymphomas. They are very uncommon in children aged under 10, but are a young adults' disease, peaking at 20 years of age. However, after the age of 50, incidence increases. Potential cause: Epstein-Barr virus (glandular fever), carcinogen exposure and immunodeficient people Cure rate: 80% Characteristics: arises in a single lymph node and spreads to adjacent nodes, cervical lymphadenopathy most common, involves malignant variants of B lymphocytes called Reed-Sternberg cells  with large and prominent nucleoli, painless non-tender progressive enlargement of lymph nodes (com...

What are the types of Leukemia? Leukemias make up approximately 10% of all cancers and are not gender or ethnic specific. Most commonly, leukemias present in younger children whose prognosis is considerably better than an adult's. Leukemia is an uncontrolled proliferation of leukocytes. This means that normal bone marrow is replaced by immature and undifferentiated leukocytes or blast cells. These abnormal leukocytes then infiltrate the bloodstream and circulate in the blood, which takes them to the liver, spleen, lymph nodes, kidneys and other resting sites. The overcrowding of the leukocytes interrupts the maturation of other blood cells. Leukemia is either acute, meaning they are rapidly spreading, or chronic, meaning they have a slow course. Acute leukemias involve immature poorly differentiated leukocytes, whereas chronic leukemias involve mature well differentiated leukocytes. The types of leukemias are described below:   1.   Acute Lymphocytic Leukemi...

What are the types of anaemia?   1.   Iron-Deficiency Anaemia Importance: iron is critical to the formation of red blood cells Cause: decreased intake of iron, increased demand, excessive blood loss Red blood cell (RBC) state: microcytic and hypochromic NOTE: ingested iron moves into the plasma where it binds to transferrin, which is then absorbed into the liver or bone marrow. It is the recycling of red blood cells in the spleen that returns this iron into the bloodstream.   2.   B₁₂ and Folate Deficiency Anaemia (Pernicious Anaemia) Importance: vitamin B₁₂ and folic acid play a role in red blood cell maturation RBC state: microcytic (megaloblastic) and low hematocrit   3.   Aplastic Anaemia Cause: failing haemopoietic stem cells, decreasing levels of red blood cells, white blood cells and platelets due to radiation, chemotherapy, drugs, viruses and autoimmune diseases RBC state: normocytic, normochromic and low c...

Why do we have to produce red blood cells? Red blood cells transport oxygen from our lungs to our tissues, where they play a role in aerobic respiration (cellular metabolism). This provides our cells with enough energy to undergo cell division, protein synthesis and many other critical functions for our survival. But what happens when oxygen serum levels are low? Peritubular cells in the kidneys produce erythropoietin Proliferation and maturation of red blood cells occurs in the red bone marrow Reticulocytes (immature red blood cells) are released into the blood Mature red blood cells enter circulation Oxygen levels are normalised Red blood cells have a reasonably long lifespan at approximately 120 days. When a red blood cell has reached its lifespan or is damaged for whatever reason, it migrates to the spleen. Here, two processes occur: Phagocytic cells destroy the old and defective red blood cells Haemoglobin is broken down into globin, which is reused for amino aci...

What is inflammation? There are three lines of defence in the body, and these are in the order of which they act: Epithelial barriers Groups of cells, tissues and organs that work together to protect the body: non-specific or innate Specific or adaptive , which can differentiate between specific microorganisms and responds accordingly, and can produce a heightened response upon re-exposure (B and T lymphocytes) Inflammation results in an exudate, which can either be: Serous, meaning there is a lot of fluid and decrease in protein Purulent, meaning it contains pus (neutrophils) Fibrinous, meaning there is a lot of fibrin Haemorrhagic, meaning it is due to severe tissue injury and damage to vessels which causes red blood cells to leak from the capillaries In acute inflammation , involved cells include neutrophils, which phagocytose, basophils and mast cells, which release histamine, and eosinophils, which are involved in allergic reactions and parasitic invasion. Each of t...

What are bacteria? Answer : unicellular organisms with a rigid cell wall (peptidoglycan), no organised intracellular organelles and a single chromosome of DNA. Some can have structures on the cell surface, such as a flagella (tail-like structure), which enables them to attach to host or aid in motility. Bacteria reproduce by simple division due to the single chromosome of DNA. Bacteria are classified by their shape, oxygen requirements and Gram staining: Shape: Cocci, meaning they are round Bacilli, meaning they are rod-shaped Fusiform, meaning they are spindle-shaped Spirochetes, meaning they are tightly spiralled Oxygen Requirements: Anaerobic (oxygen is toxic to them) Aerobic (require oxygen to survive) Gram Staining: Purple, meaning there is a lot of peptidoglycan in the cell wall Pink, meaning there is only 10% peptidoglycan in the cell wall What are viruses? Answer: small infectious agents (smaller than bacteria) and require living hosts which they inv...

What is hypersensitivity? Hypersensitivity, as the name suggests, is the excessive or inappropriate activation of the immune system due to exposure to exogenous or endogenous antigens. When a reaction takes place, inflammation occurs and there is also some tissue and cell damage. Antibodies responsible for hypersensitivity reactions: IgE IgD IgA IgM IgG There are four types of hypersensitivity: TypeⅠ: Intermediate Hypersensitivity Immediate hypersensitivity involves the antibody IgE, with examples being allergies and anaphylaxis. Evidence of the reaction begins within minutes of the antigen challenge, after the antigen is inhaled, ingested, injected or comes into contact with skin. Examples of this include: Atopic dermatitis (eczema) Allergic rhinitis (hayfever) Asthma Food reactions Anaphylaxis (widespread vasodilation and oedema) Steps in the reaction of IgE against a foreign antigen are outlined below: Initial antigen exposure to the B lymphocytes ...

Development of epithelial malignancy An outline of the development of an epithelial malignancy, i.e. carcinoma, which is most definitely malignant is written below: The epithelium on the basement membrane is normal with the lymphatics and blood vessels normally positioned below the membrane. Random dysplasia in the cells (change in their structures) causes them to have abnormally large nuclei with injured DNA. The cells, however, are not yet malignant. Carcinoma in situ is the next step, where further DNA injury transforms the cells into a malignancy which cannot yet metastasize. The carcinoma in situ becomes an early invasive carcinoma, where additional DNA damage produces malignant cells that penetrate the basement membrane. The carcinoma cells then invade the blood vessels and lymphatics beneath the penetrated basement membrane, and distant metastasis occurs. NOTE: Metastasis means that cancerous cells have reached another part of the body via travel through the blood and ly...

What is disease? Disease is the failure to maintain homeostatic conditions and pathophysiology is the study of functional changes caused by disease. In pathophysiology, we understand that there are four aspects that form its core: Etiology Mechanisms of development Structural alterations induced in the cells and organs of the body (morphological changes) Functional consequences of the morphological changes Etiology is the identification of casual factors that provoke the particular disease, e.g. a bacterium. A disease of unknown origin is known as an idiopathic disease. Prevalence is the number of people affected with a particular disease at a given time. Pathogenesis is the development of evolution of a disease, i.e. invasion of the body, proliferation, spread, evolving inflammatory response, immunologic defences of the host and destruction of cells and tissues. A symptom is a patient's perception of a change in their normal body function. They are difficult t...