Immunity and Recombinant DNA Flashcards
1
Q
Define Pathogen
A
- A disease causing organism, often referred to as a pathogenic organism
2
Q
Define contagious
A
- When a disease can be passed on via direct contact
- vector transmission = passed on by mosquito
- vector = carrier
3
Q
What are Bacteria
A
- single cell organisms that are for the most part harmless
- Bacteria are classed mainly on shape
4
Q
What are the main features of Bacteria?
A
- No nucleus or membrane bound organelles
- All have a cell membrane
- Has grainy cytoplasm due to ribosomes
5
Q
Define virus
A
- A virus is genetic material in a protein coat
- Viruses infect body cells causing them to create more viral particles
- Eventually the particles leave the host cell and infect other cells
6
Q
What are the main features of a virus?
A
- Contains RNA or DNA or both
- No nucleus organelles or cytoplasm
- Some have lipoprotein envelop
- Envelop may have proteins which facilitate adherence to cells
- Envelop also provides protection
7
Q
Define what is a viral infection and state the 6 steps of it occurring.
A
- An infection after a random collision between a viral particle and a appropriate host cell
- Viruses will bind to a matching receptor on the cells surface
- Merge with the lipid bilayer of a cell or be engulfed by the cells- a virus will lose its envelop at this point.
- Uncoating - The protein coat is removed in either the cytoplasm or nucleus of infected cell.
- Transcription and translation of viral proteins using hijacked cell machinery
- Viral proteins assembled into new viruses
- Release of viruses through cell autolysis (self bursting) or apoptosis, or in the case of HIV and Herpes the virus uses endocytosis to leave with lipoprotein envelops.
8
Q
What are non-specific defences
A
- Defences that work against all pathogens, they are the first line of defence and try stop the pathogen from entering the body.
9
Q
Name and describe the external non- specific defences?
A
- Skin- physical barrier, other bacteria occupies skin thus difficult for pathogens to become established, secretes sebum which can kill pathogens
- Mucous membranes- line body cavities and secrete mucous preventing entry of pathogens into body.
- Hairs - used to trap particles and prevent them moving through respiratory system
- Cilia- hair projections on cells which move with beating motion. Role is to move mucous with trapped micro- organisms to throat to be coughed out or swallowed.
- Acids- Acidic fluid which can destroy micro-organisms e.g sweat
- Lysosomes- bacteria killing enzyme, found in tears sweat saliva, secretions of nose and tissue fluid.
10
Q
Name and describe the protective reflexes.
A
- sneezing- stimulus= irritation of walls of nasal cavity, carries mucous, foreign particles and irritating particles out of mouth and nose.
- Coughing - stimulus = irritation of lower respiratory tract, forceful expulsion drives mucous and foreign particles out trachea and towards throat and nose.
- Vomiting - stimulus = excessive stretching of stomach and bacterial toxins, contraction of abdominal muscles and diaphragm that expel stomach content.
- Diarrhoea - stimulus = Irritation of small and large intestines by pathogens, contractions of muscle of walls to remove pathogen as quick as possible, doesn’t allow H20 absorption.
11
Q
Name and describe the internal Non-specific defences
A
- Phagocytosis - cell eating, pathogenic particles engulfed and digested
- Leucocytes (white blood cells) - can secrete substances which can kill bacteria before they engulf them or they just engulf them live, Can leave blood capillaries and migrate through tissues to site of infection
- macrophages - Develop from 2 leucocyte called monocyte, some can wander others sit in place and wait for bacteria, digest pathogens or secrete substance to destroy them
- Inflammation - purpose- reduces spread of pathogens, destroys them and prevents their entry, remove damaged tissue and cell debris, repair damaged tissue
12
Q
What are the typical signs of a inflammatory response
A
- redness, swelling, heat and pain
13
Q
What are the 7 steps of inflammation
A
- Damage by mechanical means stimulates mast cells to release heparin, histamine and other substances into tissue fluid.
- Histamine increases permeability of capillary walls to allow fluid to be filtered from blood and increases blood flow (vasodilation). Increase blood flow causes heat and redness, escape of fluids causes swelling.
- Heparin prevents clotting in immediate vicinity, allowing flow of blood to the injury allowing phagocytes to be attracted by chemicals released by mast cells.
- Other chemicals (cytokines) released by mast cells attract phagocytes to area.
- Abnormal conditions stimulate nociceptors so person feels pain in the area.
- Phagocytes (particularly neutrophils) eat until the die/explode creating puss.
- Eventually new cells produced by mitosis as part of repair.
14
Q
What is fever and state the effects?
A
- Fever is an elevation in body temperature caused by an increase in the bodies thermostat
increase in body temp will
- inhibit growth of bacteria and viruses
- speed up rate of chemical reactions, allowing cells to repair themselves faster
- Due to higher set point the body feels cold and responds by trying to increase body temp. ( by shivering etc.)
- Fever can be fatal if body temp rises above 45-49 degree
15
Q
What are pyrogens and what do they do?
A
- Pyrogens are chemicals released by white blood cells during inflammatory response which act directly on hypothalamus.
- pyrogens inhibit heat sensing neurons and excite cold sensing neurons, altering temp sensors to deceive hypothalamus into thinking its cold so hypothalamus raises body temp.
