4.1.1 Communicable Diseases

Question 1

what is a communicable disease?

Answer 1

a disease caused by a pathogen that can be passed form one organism to another

Question 2

what is a pathogen?

Answer 2

a disease causing microorganism

Question 3

what is a vector? common vectors?

Answer 3

an organism that carries pathogens form one organism to another
- water and insects

Question 4

name the types of pathogens?

Answer 4

bacteria, viruses, fungi, protoctista

Question 5

what do bacteria not have?

Answer 5

no membrane bound organelles / nucleus

Question 6

ways in which bacteria are classified?

Answer 6

• basic shapes

- basic structure of cell wall

Question 7

basic shapes of bacteria?

Answer 7

• rod shaped (bacilli): food poisoning
• spherical (cocci): acne
• comma shaped (vibrios): cholera
• spiralled (spiralli): stomach ulcers
• corkscrew (spirochaetae)

Question 8

how to bacteria replictae?

Answer 8

binary fission

Question 9

why do bacteria replicate using binary fission? problems with this?

Answer 9

• faster, exponential growth
• allows large colonies to be made
  + can cause food spoilage
  + rapid spread of disease

Question 10

function of capsule in bacterial cells?

Answer 10

• protects cell from indigestion by phagocytosis
• helps them cling together and to various surfaces
• prevents drying out

Question 11

types of cell wall in bacteria? what does the cell wall determine?

Answer 11

• gram positive: purple under a light microscope
  MRSA
• gram negative: red under a light microscope
  E. Coli
• how the bacteria responds to antibiotics

Question 12

what is a virus?
diameter?
how much smaller than a bacterium?
basic structure of a virus?

Answer 12

• non-living infectious agent
• 0.02μm
• 50 x
• some genetic material surrounded by proteins

Question 13

what is a bacteriophage?
what does it do?
what are they used for today?

Answer 13

• a virus that kills bacteria
• take over bacteria and use them to replicate and destroy bacteria
• used to identify and treat some diseases

Question 14

how do bacteria cause disease?

Answer 14

• produce toxins

- the symptoms they cause are due to the damage to the call membrane/enzymes/genetic material

Question 15

basic structure of a bacteriophage?

Answer 15

• looks like a spider lol
• long tube: injection tube
• tail plate attached below the injection tube
• head contains loose genetic material and protein coat

Question 16

describe how viruses invade living cells?

Answer 16

-

Question 17

what is the body’s first line of defence?

Answer 17

skin, clots seal wound

Question 18

what is a non-specific defence?

Answer 18

targets any type of pathogen

Question 19

non-specific defence: mucus?

Answer 19

contains lysosomes which destroy the cell wall of pathogens

Question 20

non-specific defence: what parts of the body contain mucus? lysosomes?

Answer 20

mucus: air tracts, nose
lysosomes: tears, sweat, saliva, urine

Question 21

non-specific defence: urine

- women?

Answer 21

lysosomes
allows physical washing of urinal tract
- in women, menstruation and discharge allows washing of the urinary tract

Question 22

non-specific defence: expulsive reflexes

Answer 22

coughing, sneezing: expel mucus

vomiting/diarrhoea: expel contents of the gut

Question 23

non-specific defence: what is thrush?

Answer 23

caused by pH change in vagina

Question 24

non-specific defence: ear

Answer 24

contains wax which works like mucus

Question 25

non-specific defence: eye

Answer 25

rapid eye movement moves pathogens to front of eye to be washed away by tears - micrboes die in the salty conditions of tears

Question 26

non-specific defence: gut

Answer 26

good gut bacteria (probacteria) and in breast milk | - compete with bad bacteria

Question 27

non-specific defence: skin

Answer 27

sebaceous glands secrete an oily substance called sebum which inhibits the production of pathogens

Question 28

non-specific defence: birth reflex?

Answer 28

when the baby is pushed down, it pushes against the birth canal which causes the uterus to push the baby down

Question 29

non-specific defence: anus

Answer 29

defacating expels pathogens in diet | - ring of muscle in anus is a good physical barrier for pathogens

Question 30

explain dead skin cells?

Answer 30

outer layer of skin called epidermis contains layers of cells these cells are called keratinocytes produced by mitosis at the base of the epidermis migrate to surface of skin as they migrate, they dry out the sytoplasm is replaced by the protein keratin called KERATINISATION takes 30 days by time cells reach surface, no longer alive - this keratinised layer of dead cells acts as an effective barrier for pathogens

Question 31

describe what happens during blood clot formation (not cycle)

Answer 31

skin is breached, pathogens enter platelets come into contact with collagen in the blood vessel, they ADHERE and secrete various substances - thromboplastin - seratonin clot dries epidermal stem cells mitose and migrate to top of epidermis and differentiate forming new cells - scab sloughs off, wound healed :D

Question 32

what is the function of thromboplastin in the blood clot response?

Answer 32

- enzyme that initiates a cascade of events that lead to a blood clot (memorise the cycle)

Question 33

what is the function of serotonin in the blood clot response?

Answer 33

- causes the smooth muscle to contract, restricting blood vessel and reducing blood flow to area

Question 34

describe the inflammatory response?

Answer 34

presence of microorganisms detected by specialised cells called MAST CELLS release a cell-signalling substance called HISTAMINE and CYTOKINES (more)

Question 35

what do histamines do in the inflammatory response?

Answer 35

- make blood vessels dilate, causing localised heat and swelling: raised temp prevents pathogens form REPRODUCING - make blood vessels more leaky, forcing blood plasma out of capillaries, called tissue fluid CAUSES SWELLING AND OEDEMA - drain into lymphatic system

Question 36

what do cytokines do in the inflammatory response? fever?

Answer 36

attract phagocytes to site | - stimulate hypothalumus to reset the thermostat and temp goes up

Question 37

why is a high temp useful for killing pathogens?

Answer 37

- high temp pathogens dotn reproduce well | - specific immune system works faster

Question 38

types of phagocytes?

Answer 38

- neutrophils: multi-lobed nucleus, manufactored in bone marrow10 mins to engulf, get through pores in capillaries - macrophage:

Question 39

describe phagocytosis in neutrophils

Answer 39

1) phagocyte binds to the opsonin attached to the antigen of the pathogen 2) the cell membrane of the phagocyte fuses around the bacterium, enclosing it in a vacuole by endocytosis- phagosome 3) a lysosome fuses with the vacuole: phagolysosome and empties its digestive enzymes to digest it 4) antigens are presented on the surface, useful products are taken into the cytoplasm by diffusion / AT

Question 40

describe phagocytosis in macrophages

Answer 40

-