Ch. 10 Protection Against Invaders Flashcards
Define communicable disease
(infectious/transmissible): a disease passed from one to another by infection with microorganisms
what are communicable diseases caused by and spread by
- caused by pathogens
- spread by person to person by direct contact (contagious)
or vectors
Define pathogens and four examples
> Pathogens: a disease causing organism - Types of pathogens: o o Bacteria o Virus o Fungi o Animal parasites
Are bacteria usually non pathogenic and what can they be used for/ found
- Majority of bacteria = non- pathogenic
o Essential to life
o Large # live in alimentary canal, on skin
define bacteria
unicellular microorganism, lack organelles
What are bacteria classified by (and what are the classifications)
- 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)
define virus
an infectious agent, totally dependent on living cells for reproduction
what are three characteristics of virusues
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
what can viruses either cause
o Viral infection
o No harm (some used to insert genes into other organisms) , (bacteria also genetically modified in this way to produce insulin)
how do viruses reproduce (5 steps)
- 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
what are the six ways pathogens are transmitted
- by contact
- body fluids
- by droplets
- ingestion
- airborne
- vectors
What are the two major defences against disease and define
- Non- specific: defences of the body that act against all pathogens
- First line of defense
- Works against all pathogens - Specific: defences of the body that are directed against specific pathogens
what are the four non specific defences
- External
- Protective Reflexes
- Internal Non-specific
- Blood Clotting
What are the 8 external defences of the body
Skin mucus membrane hair cilia acid lysozyme cerumen flushing action
Explain the external defense of skin
+ 3 ways it stops entry
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
Explain the external defense of mucus membrane
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
Explain the external defense of hairs
o Nose cavity and ears
o Hairs + layer of mucus stop 90% of particles inhaled when breathing
Explain the external defense of cilia
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
Explain the external defense of acids
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
Explain the external defense of lysozyme
o Enzyme that kills bacteria
o Found in tears (eyes protected by flushing action of tears), sweat, saliva, secretions of nose and tissue fluid
Explain the external defense of cerumen
o Ear wax
o Protects ears from some bacteria
o Slightly acidic, contains lysozymes
Explain the external defense of flushing action
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
What are the four protective reflexes that protect against invaders
sneezing coughing vomiting diarrhoea
What is the stimulus and reflex for sneezing
- Stimulus: irritation of walls of nasal cavity
- Reflex: forceful expulsion of lungs carries mucus, foreign particles and irritating gases out through nose and mouth
What is the stimulus and reflex for coughing
- 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
What is the stimulus and reflex for vomiting
- 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
What is the stimulus and reflex for diarrhoea
- 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
What are the three internal non specific defences
phagocytes
inflammatory response
fever
Define phagocytes and the two types
cells that are able to engulf micro-organisms and cells debris
leucocytes and macrophages
What is the role of leucocytes in non specific
♣ Movement: leave blood capillaries + migrate through tissue to places of injury/infection
♣ Destroying Processes: Phagocytosis, secrete substances before engulfing them
What is the role of macrophages in non specific
♣ 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
What are the three purposes of inflammation
o Reduce spread of pathogens, destroy them, prevent additional entry
o Remove damaged tissue and cell debris
o Begin repair of the damaged tissue
What are the 7 steps in the inflammatory response
- 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
- 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
- Heparin prevents clotting in immediate area of injury. A clot of fluid around damaged area forms > prevents spread of pathogen into healthy tissue
- Chemicals released by mast cells attract phagocytes. Macrophages and leucocytes actively consume micro-organisms and debris by phagocytosis
- Abnormal conditions in tissue stimulate pain receptors= person feels pain
- Phagocytes (filled with bacteria, debris and dead cell) die + them and fluid= pus
- New cells produced by mitosis and repair of damaged tissue takes place
What are the 7 steps in the inflammatory response (cheat words)
1. mast cells 2, histamine 3. heparin 4. phagocytes 5. pain 6. repair
define fever and what its controlled by
elevation of body temp above 37 degrees
hypothalamus
what are the five steps of a fever
- Person feels cold > vasoconstriction + shivering
- Both activities in 1) conserve heat + increase heat production= drive temp up rapidly
- Increase temp= higher metabolic rate > increases temp further
- 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 - Temp falls back to normal
how is a fever beneficial (2)
o High body temp= inhibit growth of some bacteria + viruses
o Heat speeds chemical reactions= help cells repair themselves quicker
Explain the four steps of the lympathic system in non specific defense
- Lymph enters lymph nodes (can contain pathogenic microorganisms)
- Nodes contain masses of lymphoid tissue (crisscrossed in mesh) where large particles such as bacteria are trapped
- Trapped particles destroyed by
a. macrophages via phagocytosis
b. Projections of macrophages surround the particle and take it into the cell > destroyed by enzymes - When infection occurs formation of lymphocytes increase > swollen nodes
