DDT 1 - Intro to Disease

Question 1

Disease

Answer 1

Any disturbance of the structure or function of the body (that is harmful to the organism)

Question 2

Pathology

Answer 2

Study of disease, (pathologist = physician who can compare/contrast the histology/morphology of cells)

Question 3

Symptoms

Answer 3

Subjective manifestations (e.g. pain, weakness, headache)

Question 4

Signs

Answer 4

Physical findings/objective manifestations (e.g. swelling, redness)

Question 5

Asymptomatic vs Symptomatic Disease

Answer 5

Depends on extent
Early stages usually asymptomatic, progresses to symptomatic if not treated

Question 6

Etiological Agent

Answer 6

Agent responsible for causing disease (e.g. ebola virus causes ebola)

Question 7

Pathogenesis

Answer 7

Process of development of disease (pathogen = microorganism that causes disease)

Question 8

Chronic vs Acute

Answer 8

Chronic - develops and worsens over an extended period of time, e.g. atherosclerosis, cancer, multiple sclerosis, diabetes, COPD
Acute - symptoms appear and change or worse rapidly, e.g. flu, fracture, appendicitis, heart attack

Question 9

5 Main Classifications of Disease

Answer 9

1. Congenital/hereditary
2. Inflammatory
3. Degenerative
4. Metabolic
5. Neoplastic

Question 10

Congenital & Hereditary Diseases

Answer 10

Developmental disturbances
Causes: genetic abnormalities; abnormalities in chromosome number or distribution; intrauterine injury; interaction of genetic and environmental factors
e.g. Hemophilia (hereditary), German measles (congenital)

Question 11

Inflammatory Diseases

Answer 11

Body reacts to injury through an inflammatory process
- Bacteria or microbiologic agents: sore throat
- Allergic reaction: hay fever
- Autoimmune diseases: SLE, diabetes type 1
- Unknown etiology

Question 12

Degenerative Diseases

Answer 12

Tissue or organ degeneration as a result of aging or breakdown
e.g. Osteoarthritis, Atherosclerosis, Osteoporosis, Alzheimer’s, Muscular Atrophy

Question 13

Metabolic Diseases

Answer 13

Disturbance in metabolic process in body
e.g. Hyper/hypothyroidism, fluid and electrolyte imbalance

Question 14

Neoplastic Diseases

Answer 14

Uncontrolled cell growth
Benign: lipoma
Malignant: Lung cancer

Basis of classification
1. Similarity of lesions
2. Similarity of pathogenesis

Question 15

Diagnosis

Answer 15

Determination of nature & cause of illness
- Clinical History
- Physical Exam
- Differential Diagnosis

Question 16

Prognosis

Answer 16

Eventual outcome of disease

Question 17

Treatment

Answer 17

• Specific treatment - directed at underlying cause
• Symptomatic treatment - alleviates symptoms, does not influence course of disease

Question 18

Clinical History (5 parts)

Answer 18

1. History of Current Illness (severity, time of onset, character of symptoms)
2. Medical History (details of general health and previous illnesses that may she light on current problems)
3. Family History
4. Social history (patient’s occupation, habits, alcohol/tobacco consumption, general health, current problems)
5. Review of Symptoms (symptoms other than disclosed in history of present illness, suggesting other parts of the body affected by disease)

Question 19

Physical Exam

Answer 19

Systematic Examination of patient, emphasis on body parts affected by illness
Abnormalities noted correlated with clinical history

Question 20

Differential Diagnosis

Answer 20

Consideration of various diseases/conditions that may also explain symptoms & signs
Diagnostic possibilities narrowed by selected laboratory tests/diagnostic procedures
Opinion of medical consultant may be sought

Question 21

Diagnostic Tests

Answer 21

Screening tests for detection of disease, detect early asymptomatic diseases amenable to treatment to prevent/minimize late-stage organ damage
e.g. blood, cytological smear, topical swabs, faeces, bronchiolar lavage, biopsy, sputum, serum, plasma

Question 22

Clinical Laboratory tests

Answer 22

Purpose: To determine concentration of substances in blood or urine frequently altered by disease
Uses:
- Determine concentration or activity of enzymes in the blood
- Evaluate function of organs
- Monitor response of certain cancers to treatment
- Detect disease-producing organisms in urine, blood, faeces
- Determine response to antibiotics

Question 23

Screening for Genetic Diseases

Answer 23

• To screen for carriers of some genetic diseases transmitted from parent to child as either dominant or recessive trait
• Identifying carriers allows affected persons to make decisions on future childbearing or management of current pregnancy
  e.g. recessive gene for sickle cell anemia in 8% of Black population

Question 24

Electrical Activity Tests

Answer 24

To measure electrical impulses associated with bodily functions and activities
ECG: measures serial changes in electrical activity of the heart in various phases of the cardiac cycle

Question 25

Radioisotope Studies

Answer 25

Evaluate organ function by determining rate of uptake and excretion of substances labeled with a radioisotope
Uses:
- Anemia: radioisotope-labeled vitamin B12
- Hyperthyroidism: radioactive iodine

Question 26

Endoscopy

Answer 26

• To examine interior of body using rigid or flexible tubular instruments equipped with lens and light source
• To perform surgery formerly done through large abdominal incisions
  e.g. Bronchoscope: trachea and major bronchi; Cystoscope: bladder; Laparoscope: abdomen

Question 27

X-ray

Answer 27

Principle: use of high-energy radiation waves at lower doses to produce images to help diagnose disease
- Can penetrate through tissues at varying degrees depending on tissue density
- Act on a photographic film or plate (roentgenogram) as the rays leave the body

Radiopaque: appears white on film; high-density tissues such as bone absorb most of the rays
Radiolucent: appears dark on film; low-density tissues allow rays to pass through

Question 28

Computed Tomographic (CT) scans

Answer 28

Principle: radiation detectors record amount of X-rays or ionizing radiation absorbed by body and feed data into a computer that reconstructs the data into an image
- Radiopaque and radiolucent tissues appear white and dark as in a conventional x-ray
- Individual organs sharply demarcated by planes of fat that appear dark because of its low density
- Delivers higher dose of ionizing radiation than x-ray

Uses of computed tomographic (CT) scans
- Cancer screening asymptomatic individuals
- Detect abnormalities in internal organs that cannot otherwise be identified by standard x-ray

Question 29

Magnetic Resonance Imaging

Answer 29

Principle: computer-constructed images of body based on response of hydrogen protons in water molecules when placed in a strong magnetic field
- Protons align in the direction of the magnetic field
- Protons are temporarily dislodged and wobble when radiofrequency waves are directed at them
- Protons emit a measurable signal (resonance) that can be used to construct images
- Intensity of resonance depends on water content of tissues, strength and duration of radiofrequency pulse

MRI: advantages over CT scan
- Does not use ionizing radiation
- Can detect abnormalities in tissues surrounded by bone, such as spinal cord, orbit, skull
- Bone interferes with scanning because of its density but does not produce an image in MRI because of its low water content
- Uses: Multiple sclerosis, Superior to mammography in detecting breast cancer

Question 30

Cytologic & Histologic Examinations

Answer 30

• Papanicolau (Pap) smear: identifies abnormal cells in fluids or secretions; for recognizing early changes that may be associated with cervical and other cancers
• Biopsy: tissue samples obtained for histologic examination to determine abnormal structural and cellular patterns accompanying disease, (e.g. Liver, kidney, bone marrow)

Question 31

Therapeutics

Answer 31

Use of drugs and method of their administration in the treatment of disease

Pharmaceutical Therapy:
Pain relief
Adjustment of enzyme levels
Replacement of natural protein
Control of hormone levels

Chemotherapy:
Eliminates cells that divide frequently
Cancer cells + rapidly dividing normal cells found in the: mouth, skin, hair, bone marrow, digestive tract, kidneys, bladder, lungs, nervous system, reproductive system
Normal cells recover quickly, side effects disappear gradually
How soon the patient will feel better depends on overall health, types of anticancer drugs used
E.g. Cisplatin, 5 fluorouracil