SFBH S4

Question 1

Identify the first line of defence non specific barriers

Answer 1

skin. mucous membranes. cilia. chemical barriers, Body secretions.

Question 2

Give a description of the defence barrier ‘skin’

Answer 2

• Skin continually grows through new cells developing beneath
• Cells fit tightly together to form protective layer
• Outer layer contain keratin  microorganisms cannot penetrate unless broken

Question 3

What does the defence barrier of skin do?

Answer 3

• Mechanical barrier
• Protects other tissues
• Collects and holds pathogens
• Secretes sebum  produce acids that inhibit growth of bacteria and fungi
• If skin broken?  blood-clotting mechanism rapidly seals wound to prevent entry of pathogens

Question 4

Give a description of the defence barrier ‘Mucous Membranes’

Answer 4

• Line digestive, respiratory, reproductive and urinary tracts with mucus

Question 5

Give a description of the defence barrier ‘Cilia

Answer 5

• Tiny hairs projected from cells lining nose, trachea and bronchial tubes

Question 6

Give a description of the defence barrier ‘Chemical Barriers’

Answer 6

• Acid in stomach
• Alkali in small intestine
• Enzyme lysozyme in tears

Question 7

Give a description of the defence barrier ‘Other Body Secretions’

Answer 7

• Secretions from sweat glands

* Oily secretion from hair

Question 8

What does the defence barrier of mucous membranes do? do?

Answer 8

• IgA antibody  Protects against invasion of pathogens

Question 9

What does the defence barrier of Cillia do?

Answer 9

• Movement of mucous  any particles trapped in mucous move to nose opening or pharynx  coughed out or swallowed

Question 10

What does the defence barrier of Chemical Barriers do?

Answer 10

• Stomach acid  destroys pathogens, Inc. those carried to throat by cilia and swallowed
• Alkali  destroys acid resistant pathogens
• Lysozyme  destroys cell membranes of bacteria

Question 11

What does the defence barrier of other body secretions do?

Answer 11

• Protect body from invasion

* Contains chemicals that destroy bacteria and fungi

Question 12

What do antigens do?

Answer 12

they trigger an immune response

Question 13

What is an Antigen?

Answer 13

• Antigen: any foreign substance e.g. virus
o Protein molecules that trigger immune response  because of production of specific antibodies
o Each pathogen has its own antigen

Question 14

Why do organ transplants trigger an immune response?

Answer 14

• Antigen-antibody response  result from rejection of transplanted tissue
• Transplanted tissue fails to live and become part of organism
• Transplanted tissue contains antigens  identified by body as containing foreign antigen  triggers immune response

Question 15

The second line of defence - non specific responses- name the defence adaptions there are.

Answer 15

inflammation response, phagocytosis, lymph system, cell death to seal off pathogen

Question 16

Give a description of the second line of defence adaption ‘inflamation response’

Answer 16

• Designed to isolate and destroy foreign particles
• Prepare tissues for healing
• Dilation of blood vessels  increasing blood flow and raising temperature of tissue
 Helps confine pathogen for WBC to destroy it
• Mediated by chemicals such as histamine and prostaglandins released by damaged tissues

Question 17

Give a description of the second line of defence adaption ‘Phagocytsis’

Answer 17

• Phagocytes  WBCells that engulf and destroy micro-organisms
• Important  body’s immediate defence against infection
• Acute inflammation (lasting hours or days)  neutrophils
• Chronic inflammation (weeks or months)  macrophages

Question 18

Give a description of the second line of defence adaption ‘Lymph System’

Answer 18

• Fight disease at second and third line of defence
• System of vessels
• Drains intercellular fluid back to blood
• Contain spleen, bone marrow and thymus
• Lymph nodes  filter out foreign bodies e.g. harmful bacteria and cell debris
 contain lymphocyte and macrophages
 found in armpits, neck and groin
 enlargement  sign of infection

Question 19

Give a description of the second line of defence adaption ‘Cell death to seal off pathogen’

Answer 19

• After phagocytes destroy antigen  die
• Phagocytes – Macrophages and Lymphocytes  Form region that contains dead cells and phagocytes
 Thick layer of dead cells off pathogen in structure like cyst
 Prevents entry of nutrients to pathogen  killing it

Question 20

Name a disease that results from an imbalance of microflora in humans

Answer 20

Candidiasis

Question 21

Candidiasis is caused by…

Answer 21

• Caused by fungus Candida albicans
o Natural micro-organism
o Occurs in mouth, respiratory tract, female genital tract and gastrointestinal tract

Question 22

Candidasis occurs when…

Answer 22

there is an when imbalance of Candida albicans cells
o Usually kept in balance by competition from other micro-organisms, such as lactobacilli (bacteria found in gastrointestinal tract)

Question 23

The increase of Candida can be caused by?

Answer 23

o	Taking antibiotics or steroids 
o	Use of oral contraception 
o	Pregnancy 
o	Malnutrition 
o	Diabetes mellitus