Lecture 2: Concepts In Health And Disease

Question 1

Define health.

Answer 1

Health is a “state of complete physical, mental, and social well-being, not merely the absence of disease or infirmity”. – WHO

Different perspective for the construction of the definition health and disease …

Question 2

What is physiology?

Answer 2

The branch of biology that studies the functional activities and its mechanisms in biological systems.

Question 3

What is pathophysiology?

Answer 3

The study of the functional changes associated with or resulting from a disease or injury.

Question 4

What is pathology?

Answer 4

The study of the causes and effects of diseases. It involves the diagnosis of diseases.

Question 5

What is a pathogen?

Answer 5

An organism that can cause disease.

Question 6

How are diseases classified?

Answer 6

Anatomical, Physiological, and Pathological.

Question 7

What does an anatomical disease classification mean?

Answer 7

It is based on the organs that have been affected.

Question 8

What does a physiological disease classification mean?

Answer 8

A description of a disease that affects process or a function.

For example: metabolic, digestive, or respiratory diseases.

Question 9

What does a pathological disease classification mean?

Answer 9

It is based on the nature of the disease.

For example: neoplastic (abnormal growth) diseases, inflammatory diseases.

Question 10

How many types of diseases are there? State them.

Answer 10

4 main types.

Deficiency

Genetic (both hereditary and non-hereditary)

Physiological

Infectious

Question 11

How do deficiency diseases occur?

Answer 11

They are caused by a lack of essential nutrients in diets. It is commonly associated by malnutrition.

Question 12

What are some illnesses that result from a deficiency disease?

Answer 12

• Scurvy (Vitamin C deficiency).

• Kwashiorkor (Protein deficiency).

• Anaemia (Deficiency of red cells or of haemoglobin).

• Rickets (Vitamin D deficiency, soft/weak bones).

Question 13

What is a genetic disease?

Answer 13

A disease that occurs due to genetic mutations. It can be inherited or acquired.

Question 14

What are some examples of genetic diseases?

Answer 14

• Down syndrome – A genetic condition where a person is born with an extra copy of chromosome 21.

• Haemophilia – An inherited disorder in which the blood does not clot due to insufficient clotting factors.

• Cystic fibrosis – Accumulation of sticky mucus in the lungs and digestive system.

• Turner syndrome – A completely or partially missing X chromosome.

• Triple X syndrome – A genetic condition where a female is born with an extra X chromosome.

Question 15

What is a physiological type of disease?

Answer 15

A disease that occurs as a result of malfunctioning of the organs or systems of the body.

Question 16

What are some examples of physiological diseases?

Answer 16

• Asthma

• Diabetes

• Rheumatoid arthritis (Autoimmune disorder)

• Multiple sclerosis (Myelin)

• Hypertension

Question 17

What is an infectious type of disease?

Answer 17

A disease caused by pathogens.

Question 18

What are different transmission routes for infection diseases?

Answer 18

• Passed from person to person.

• Transmitted by insects to humans.

• Animals to humans (Zoonosis).

Question 19

What is zoonosis?

Answer 19

An infectious disease that can be transmitted from animals to humans.

Question 20

What is an acute infection?

Answer 20

An infection that lasts for short time (short-term infection).

Question 21

What is a chronic infection?

Answer 21

An infection that persists for a long time.

Question 22

What is a vector?

Answer 22

A living organism that can transmit infectious pathogens between humans, or from animals to humans.

Question 23

What is a sign?

Answer 23

An objective indicator of illness that others may be able to observe for example frequent sneezing, high temperature, blood pressure, but only trained health workers can associate with a particular disease.

Question 24

What is a symptom?

Answer 24

Subjective sensations of illness in the body that only the person who is unwell can experience for example pain, blurred vision, tiredness.

Question 25

What are the several types of pathogens?

Answer 25

• Bacteria • Viruses • Protozoa (Amoeba) • Fungi • Helminths (Parasite worm) • Ectoparasites (Flea, lives outside the host) •Prions

Question 26

What is bacteria?

Answer 26

Prokaryotic single-called organism. Can be grouped as gram positive and negative. Different shapes.

Question 27

What is the difference between gram positive bacteria and gram negative?

Answer 27

• Gram-**negative** bacteria are surrounded by a thin peptidoglycan cell wall, which itself is surrounded by an outer membrane containing lipopolysaccharide. • Gram-**positive** bacteria lack an outer membrane but are surrounded by layers of peptidoglycan many times thicker than is found in the gram-negatives.

Question 28

What are some examples of pathogenic bacteria? What are some diseases they cause?

Answer 28

• Pseudomonas aeruginosa, Streptococcus pneumoniae, Clostridium tetani. • Tuberculosis, Meningitis, Plague, Tetanus, Pneumonia, Diarrhoea.

Question 29

What are viruses? What are they made of?

Answer 29

Is an obligate (restricted to a particular function or mode of life) intercellular (not-infective outside the cell) parasite. Each viral particle (virion, what it is outside) consists of a **DNA** or **RNA**. A typical virus consists of a protective protein coat (**capsid**). *Some* have an **envelope**. Viral encoded **glycoproteins** (spike projections) e.g. neuramindiase and hemagglutinin expressed on influenza A viruses.

Question 30

What are some viral diseases?

Answer 30

Measles, influenza, and polio.

Question 31

What are protozoa pathogens?

Answer 31

Unicellular eukaryotes. Many spend their life in arthropod host such as mosquitoes or flies.

Question 32

What are some protozoan parasites and diseases?

Answer 32

**Plasmodium spp.** causing **malaria infection**. **Trypanosoma brucei** (bugs) causing **African sleeping sickness**. **Leishmania spp.** (sandflies) causing **leishmaniasis**.

Question 33

What are fungi?

Answer 33

Any of a group of spore-producing organisms feeding on organic matter. Eukaryotes; can be unicellular, multicellular, or syncytial (one cell with multiply nuclei).

Question 34

What are fungal and cutaneous infections?

Answer 34

Mycoses (infections) can result due to injury or inhalation. Cutaneous infections includes attacks on the skin, nails, or hair *e.g.* ring worm, athlete’s foot (tinea pedis) and jock itch.

Question 35

What is candida?

Answer 35

Part of the normal flora of oral activity, genitalia, skin or large intestine.

Question 36

What is oral candidiasis?

Answer 36

Thrush caused by *Candida spp*.

Question 37

What are helminths?

Answer 37

Parasitic worms, eukaryotic multicellular endoparasites (live inside the host). Grouped into **roundworms** (nematodes) and **flatworms** (Platyhelminthes including cestodes, trematodes …). Evolved evasive strategies to prolong survival in host.

Question 38

Provide the names of some types of helminths.

Answer 38

Trematodes (flukes), Cestodes (tapeworm), and soil-transmitted helminths. **Fasciola hepatica**, **Taenia saginata** (found in intestines), **Ascaris lumbricoides**.

Question 39

What are ectoparasites?

Answer 39

Organisms that are found on the outer surface of the host. Ectoparasites causing human diseases are **arthropods**; *insects* (6-legged arthropods) and *arachnids* (8-legged arthropods).

Question 40

What are some examples of ectoparasites?

Answer 40

• Fleas – causing pulicosis • Lice – causing pediculosis • Tick – Lime disease, Powassan fever • Mite – dust mite causing asthma

Question 41

What are prions? How do they work?

Answer 41

Not organisms, they are misfolded infectious proteins. They do not contain genetic material.

Question 42

What are prion diseases also known as?

Answer 42

Transmissible spongiform encephalopathies (TSEs).

Question 43

What is the difference between a normal and a disease-causing prion?

Answer 43

The PrP has been shown to participate in several biological processes, including neuritogenesis, neuronal homeostasis, cell signalling, cell adhesion, and a protective role against stress. • The normal prion protein is thought to be made up of flexible coils referred to as *alpha helices*; however, in the abnormally folded form, these helices are stretched out into densely packed structures called *beta-sheets*.

Question 44

What are some commonly known prion diseases that affect humans?

Answer 44

• Creutzfeldt-Jakob Disease (CDJ) • Gerstmann-Straussler-Scheinker Syndrome (GSS) • Fatal Familial Insomnia

Question 45

What are some ways infections get transmitted to humans?

Answer 45

• Direct person-to-person • Indirect person-to-person • Animal-to-human (Zoonotic infection) • Insect-to-human

Question 46

What are some examples of **direct** person-to-person way of transmission?

Answer 46

• Mother-to-child transmission • Handshake • Sexual contact or touch

Question 47

What are some examples of **indirect** person-to-person way of transmission?

Answer 47

• Airborne transmission • Faecal-oral • Waterborne • Foodborne • Formite (inanimate objects contaminated with pathogens) • Bloodborne

Question 48

What are some examples of animal-to-human ways of transmission (zoonotic)?

Answer 48

• Toxoplasmosis - undercooked meat, soil, cat faeces. • Trichinosis - infected meat. • Rabies - disease of dogs/mammals that gets transmitted through saliva to humans (hydrophobia).

Question 49

What are some examples of insect-to-human ways of transmission?

Answer 49

• Vector-borne diseases: ~ Malaria infection by mosquitoes ~ African sleeping sickness by Tsetse flies ~ Leishmaniasis by sandflies

Question 50

What is mortality?

Answer 50

It refers to deaths in a population.

Question 51

What is mortality rate?

Answer 51

Refers to how many deaths occur in a population over a given time. It is typically expressed per **1000** or **100,000** individuals.

Question 52

Measures of mortality includes:

Answer 52

• Infant mortality rate • Under-5 mortality rate • Maternal mortality ratio

Question 53

What is infant mortality rate?

Answer 53

The number of infant’s death between *birth and one year* of age per **1000 live** births.

Question 54

What is under-5 mortality rate?

Answer 54

The number of deaths of children *under five years* of age per **1000 live** births.

Question 55

What is maternal mortality ratio rate?

Answer 55

The number of female patients dying from *pregnancy-related* issues per **100,000 live** births.

Question 56

What is morbidity?

Answer 56

Refers to illnesses, diseases or disorders.

Question 57

What does “DALYs” stand for?

Answer 57

Disability-Adjusted Life Years.

Question 58

What does “DALYs” mean? What are they used for?

Answer 58

Years of Life Lost (**YLL**) + Years Lived With Disability (**YLD**). a.k.a **Mortality** + **Morbidity** • Used to quantify the overall burden of disease on a population.