Ch. 10 Protection Against Invaders

Question 1

Define communicable disease

Answer 1

(infectious/transmissible): a disease passed from one to another by infection with microorganisms

Question 2

what are communicable diseases caused by and spread by

Answer 2

• caused by pathogens
• spread by person to person by direct contact (contagious)
  or vectors

Question 3

Define pathogens and four examples

Answer 3

>	Pathogens: a disease causing organism
-	Types of pathogens: 
o	o	Bacteria
o	Virus
o	Fungi 
o	Animal parasites

Question 4

Are bacteria usually non pathogenic and what can they be used for/ found

Answer 4

• Majority of bacteria = non- pathogenic
  o Essential to life
  o Large # live in alimentary canal, on skin

Question 5

define bacteria

Answer 5

unicellular microorganism, lack organelles

Question 6

What are bacteria classified by (and what are the classifications)

Answer 6

• Classified by Cell Shape
  o Cocci: spherical cells (pairs or clusters)

o Bacilli: rod shaped with flagella

o Spirilla: twisted cells

o Vibrio: curved rods (comma shaped)

Question 7

define virus

Answer 7

an infectious agent, totally dependent on living cells for reproduction

Question 8

what are three characteristics of virusues

Answer 8

o Distinctive structures and differing sizes

o contain genetic material in form of DNA or RNA, but never both

o the molecule of DNA or RNA= surrounded by coat of lipoprotein

Question 9

what can viruses either cause

Answer 9

o Viral infection
o No harm (some used to insert genes into other organisms) , (bacteria also genetically modified in this way to produce insulin)

Question 10

how do viruses reproduce (5 steps)

Answer 10

• Cannot reproduce themselves, multiplies by viral replication
  1. Binds to receptor of host cell and nucleic acid enters cell
  2. The virus contains an enzyme enabling it to make copy of its nucleic acid
  3. Copy of nucleic acid integrates with hosts
  4. New viral nucleic acid produced and new virus particle forms
  5. New virus leaves host cell to infect others

Question 11

what are the six ways pathogens are transmitted

Answer 11

• by contact
• body fluids
• by droplets
• ingestion
• airborne
• vectors

Question 12

What are the two major defences against disease and define

Answer 12

1. Non- specific: defences of the body that act against all pathogens
   - First line of defense
   - Works against all pathogens
2. Specific: defences of the body that are directed against specific pathogens

Question 13

what are the four non specific defences

Answer 13

1. External
2. Protective Reflexes
3. Internal Non-specific
4. Blood Clotting

Question 14

What are the 8 external defences of the body

Answer 14

Skin
mucus membrane 
hair 
cilia 
acid 
lysozyme 
cerumen 
flushing action

Question 15

Explain the external defense of skin

+ 3 ways it stops entry

Answer 15

o Barrier covering outside of body
o Stops entry into body provided its not broken (cuts and abrasions)
o Stops entry by:
♣ Normal bacteria occupy skin area // potential pathogens find it default to establish
♣ Oily secretion (sebum) produced by oil glands in skin= contain substances that kill some pathogenic bacteria
♣ Sweat secreted contains salts and fatty acids that prevent growth of many microorganisms

Question 16

Explain the external defense of mucus membrane

Answer 16

o Line body cavities that open to exterior
o Secrete mucus which inhibits entry of microorganisms into body
o Digestive, urinary, reproductive tracts protected this way

Question 17

Explain the external defense of hairs

Answer 17

o Nose cavity and ears

o Hairs + layer of mucus stop 90% of particles inhaled when breathing

Question 18

Explain the external defense of cilia

Answer 18

o Tiny hair like projections from cells capable of beating motion
o Mucose membranes lining nose cavity, trachea have cilia
o Beating of cilia moves mucus, containing trapped particles and micro-organisms towards throat= coughed up or swallowed

Question 19

Explain the external defense of acids

Answer 19

o Acids in stomach juices kills many bacteria ingested or in mucus swallowed from nose and windpipe
o Vagina= acid secretion that reduce growth of microorganisms
Sweat= slightly acidic

Question 20

Explain the external defense of lysozyme

Answer 20

o Enzyme that kills bacteria

o Found in tears (eyes protected by flushing action of tears), sweat, saliva, secretions of nose and tissue fluid

Question 21

Explain the external defense of cerumen

Answer 21

o Ear wax
o Protects ears from some bacteria
o Slightly acidic, contains lysozymes

Question 22

Explain the external defense of flushing action

Answer 22

o Keep areas relatively free of pathogens
o Urine flowing out of urethra= cleansing actions (prevents reaching of bladder) Women= shorter urethra // more common to bladder infections
o Tears, sweat + saliva= flushing and cleansing

Question 23

What are the four protective reflexes that protect against invaders

Answer 23

sneezing coughing vomiting diarrhoea

Question 24

What is the stimulus and reflex for sneezing

Answer 24

• Stimulus: irritation of walls of nasal cavity

- Reflex: forceful expulsion of lungs carries mucus, foreign particles and irritating gases out through nose and mouth

Question 25

What is the stimulus and reflex for coughing

Answer 25

- Stimulus: irritation in lower respiratory tract (bronchi, bronchioles) - Reflex: air forced from lungs to try to remove the irritating. Air drives mucus and foreign matter up the trachea towards throat and mouth

Question 26

What is the stimulus and reflex for vomiting

Answer 26

- Stimulus: psychological stimuli, excessive stretching of stomach and bacterial toxins can all induce toxins - Reflex: not contraction of stomach by of the muscles of the abdomen and the diaphragm that expel the stomach contents

Question 27

What is the stimulus and reflex for diarrhoea

Answer 27

- Stimulus: irritation of the small and large intestines by bacteria, viruses or protozoans - Irritation causes increased contractions of the muscles of the wall of the intestines so that the irritant is removed quickly - Material does not stay in large intestine for water to be absorbed > faeces watery

Question 28

What are the three internal non specific defences

Answer 28

phagocytes inflammatory response fever

Question 29

Define phagocytes and the two types

Answer 29

cells that are able to engulf micro-organisms and cells debris leucocytes and macrophages

Question 30

What is the role of leucocytes in non specific

Answer 30

♣ Movement: leave blood capillaries + migrate through tissue to places of injury/infection ♣ Destroying Processes: Phagocytosis, secrete substances before engulfing them

Question 31

What is the role of macrophages in non specific

Answer 31

♣ Movement (two types): • Wander: move though tissues looking for pathogen + destroy • Fixed: in one place + only deal with pathogens that come ♣ Destroying Processes: either engulf + digest, or release substances

Question 32

What are the three purposes of inflammation

Answer 32

o Reduce spread of pathogens, destroy them, prevent additional entry o Remove damaged tissue and cell debris o Begin repair of the damaged tissue

Question 33

What are the 7 steps in the inflammatory response

Answer 33

1. Stimulated by mechanical damage, or local chemical changes, mast cells release histamine, heparin and other substances into tissue fluid. They stimulate and coordinate inflammation by releasing chemicals 2. Histamine increases blood flow to area and causes walls of blood capillaries to become more permeable so fluid is filtered from the blood. Increased blood flow= heat and redness associated with inflammation, escape of fluid from blood= swelling 3. Heparin prevents clotting in immediate area of injury. A clot of fluid around damaged area forms > prevents spread of pathogen into healthy tissue 4. Chemicals released by mast cells attract phagocytes. Macrophages and leucocytes actively consume micro-organisms and debris by phagocytosis 5. Abnormal conditions in tissue stimulate pain receptors= person feels pain 6. Phagocytes (filled with bacteria, debris and dead cell) die + them and fluid= pus 7. New cells produced by mitosis and repair of damaged tissue takes place

Question 34

What are the 7 steps in the inflammatory response (cheat words)

Answer 34

``` 1. mast cells 2, histamine 3. heparin 4. phagocytes 5. pain 6. repair ```

Question 35

define fever and what its controlled by

Answer 35

elevation of body temp above 37 degrees hypothalamus

Question 36

what are the five steps of a fever

Answer 36

1. Person feels cold > vasoconstriction + shivering 2. Both activities in 1) conserve heat + increase heat production= drive temp up rapidly 3. Increase temp= higher metabolic rate > increases temp further 4. Fever breaks (crisis) (thermostat reset) person feels hot + flushed= vasodilation and sweating o Resetting of thermostat= due to substances called pyrogens ♣ Released by WBC during inflammatory response to a foreign intruder ♣ Act directly on hypothalamus 5. Temp falls back to normal

Question 37

how is a fever beneficial (2)

Answer 37

o High body temp= inhibit growth of some bacteria + viruses | o Heat speeds chemical reactions= help cells repair themselves quicker

Question 38

Explain the four steps of the lympathic system in non specific defense

Answer 38

1. Lymph enters lymph nodes (can contain pathogenic microorganisms) 2. Nodes contain masses of lymphoid tissue (crisscrossed in mesh) where large particles such as bacteria are trapped 3. Trapped particles destroyed by a. macrophages via phagocytosis b. Projections of macrophages surround the particle and take it into the cell > destroyed by enzymes 4. When infection occurs formation of lymphocytes increase > swollen nodes