Normal Flora and Its Beneficial Roles Quiz

Questions and Answers

What are the beneficial roles of normal flora in the human body?

Reduces pH, changes environmental conditions, excretes antibacterial chemicals, synthesizes and secretes vitamins, stimulates local immunity

How can normal flora cause disease in the human body?

Competition for nutrients, causing disease through inflammatory response

What are the different types of bacteria based on their oxygen requirements?

Obligate aerobes, obligate anaerobes, facultative anaerobes

What temperature range do most bacteria grow between?

Between 10-39 degrees celsius Signup and view all the answers

What is the optimum temperature for pathogenic bacteria to grow?

37 degrees celsius Signup and view all the answers

How do bacteria close to pH 7 (neutral) in the human body influence health?

Bacteria close to pH 7 are able to thrive in the body's neutral environment Signup and view all the answers

What is the largest organ of the body?

Skin Signup and view all the answers

What is the outermost layer of the epidermis?

Stratum corneum Signup and view all the answers

What type of cells in the epidermis produce keratin?

Keratinocytes Signup and view all the answers

What is the function of melanocytes in the skin?

Produces melanin Signup and view all the answers

Where are Merkel cells found and what is their function?

Present in epidermis-dermis function, associated with nerve endings, function as sensory receptors Signup and view all the answers

What is the layer deep to the epidermis that makes up the bulk of the skin?

Dermis Signup and view all the answers

What is the purpose of lymphoid tissue surrounding the appendix?

Protects against GI tract bacteria Signup and view all the answers

Define Oedema and explain its cause.

Excessive accumulation of interstitial fluid due to increase in blood pressure or lymph flow obstruction. Signup and view all the answers

What are antigens and give an example of one?

Antigens are substances that induce an immune response. Example: microbes or their parts. Signup and view all the answers

Differentiate between non-specific (innate) and specific (acquired) body defences.

Non-specific defences are general defenses against all antigens and are inborn. Specific defences are specialized defenses against a particular type of antigen acquired during life. Signup and view all the answers

List three examples of first-line defenses in the body.

Skin, Mucous membranes, Fluids (tears, saliva, etc.) Signup and view all the answers

What are the components of second-line defences in the body?

Antimicrobial chemicals, Phagocytes, Natural killer cells, Inflammation, Fever Signup and view all the answers

What are the key signs of inflammation?

Redness, Heat, Swelling, Pain, Loss of function Signup and view all the answers

What is the role of phagocytosis in the process of inflammation?

Destroys and removes antigens; supports immune response Signup and view all the answers

Explain how the body responds to inflammation in terms of fever.

Systemic response, Temp regulator in hypothalamus is reset Signup and view all the answers

What is specific immunity and how does it develop?

Adaptive immunity, Develops on exposure to particular antigen Signup and view all the answers

Describe the properties of humoral immunity and its role in the body.

B lymphocytes make antibodies, Antibodies work in body fluids Signup and view all the answers

What is the importance of memory in specific defenses?

Memory formed after first exposure, Helps mount a faster response upon subsequent exposures Signup and view all the answers

What is the role of antibodies in humoral immunity?

Antibodies are made against antigens, stay in blood and lymph nodes or attached to B-cells, and target antigens for destruction. Signup and view all the answers

How do B cells contribute to the defense against bacteria?

Bacteria are mostly attacked by antibodies produced by B cells. Signup and view all the answers

Explain the two ways to activate B cells in the immune response.

Phagocytes can engulf bacteria and antigens to present to helper T cells, or antigens can directly attach to antibodies. Signup and view all the answers

What is the role of memory cells in humoral immunity?

Memory cells remember specific antigens and produce antibodies instantly upon re-exposure to the same antigen. Signup and view all the answers

Differentiate between the functions of T-helpers and cytotoxic T cells.

T-helpers aid in maturing B cells and activation of other T cells, while cytotoxic T cells destroy virus-infected and tumor cells. Signup and view all the answers

What is the function of regulatory/suppressor T cells at the end of an infection?

Regulatory/suppressor T cells decrease the T cell response to help regulate the immune system. Signup and view all the answers

Study Notes

Normal Flora (Microbiota)

Our bodies have microbes in residence on various areas such as skin, mouth, throat, and large intestine
Normal flora competes with pathogens for nutrients and space, preventing the growth of harmful microorganisms
Normal flora in skin reduces pH, creates an environment that is not conducive to the growth of pathogenic bacteria
Normal flora in the intestine excretes antibacterial chemicals, synthesizes and secretes vitamins, and stimulates local immunity
However, normal flora can cause diseases if it enters a wound or grows out of control, leading to inflammatory responses

Transmission of Microorganisms

Contact transmission: direct or indirect contact between people, or contact with contaminated objects
Vehicle transmission: transfer of pathogens through contaminated food, water, air, or fomites (objects that can carry infection)
Vector transmission: transfer of pathogens through insects or animals that carry the pathogen

Bacteria and Normal Flora

Bacteria growth requirements: optimal temperature (10-39°C), pH (neutral), and oxygen (aerobic or anaerobic)
Types of bacteria: obligate aerobes (require oxygen), obligate anaerobes (cannot grow in oxygen), and facultative anaerobes (prefer oxygen but can survive without)

Disinfection and Sterilization

Disinfection: elimination of most pathogens from inanimate objects using chemicals, heat, or radiation
Sterilization: complete elimination of all microorganisms from an object or surface

Integumentary System (Skin)

The skin covers the entire body and is the largest organ of the body
Layers of the skin: epidermis (outermost layer), dermis (deep to the epidermis), and hypodermis (subcutaneous layer)
Functions of the skin: skin color, redness, and palour; protection of underlying tissues; aid in picking things up, scratching, and digging

Defence against Bacteria

Humoral immunity: production of antibodies against antigens; antibodies stay in blood and lymph nodes or attach to B-cells
Cell-mediated immunity: T cells kill abnormal cells directly; T cells also form memory cells
Two ways to activate B-cells: phagocytes engulf bacteria and antigens to helper T-cells, or antigens attach to antibodies

Module 2 Knowledge Check

Tonsils and appendix are lymphoid tissues that protect against bacteria
Oedema: excessive accumulation of interstitial fluid due to increased blood pressure or obstruction of lymph flow

Immune System

First line defences: non-specific, inborn defences that keep invaders out
Second line defences: non-specific, inborn defences that attack invaders that have entered the body
Third line defences: specific, acquired defences that target specific antigens
Antigens: anything foreign to the body that induces an immune response
Non-specific defences: do not distinguish between threats, react the same way each time
Specific defences: specific to each antigen, develop after exposure to the antigen

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