non- specific defences

non specific denseness work against…

all pathogenic micro- organisms

specific defences work against…

particular pathogens

many pathogens are prevented from entering our body, or if they do enter…

they are delt with before they can cause symptoms or disease, even if you do become ill, body defence system often enables us to recover without medical attention

what are protective reflexes?

they expel pathogens from the body by coughing or sneezing.

what is the function of external defences?

to try and stop pathogens and other foreign particles from entering

are all external defences non-specific

yes

How does the skin provide protection as an external defence?

it is an effective barrier covering the outside of the body, the normal bacteria on skin providing protection, and the secretion of oily sebum all prevent bacteria from enterting/ growing on the body

what is the function of the skin covering the outside of the body?

it stops the entry of micro-organisms from broken skin from cuts/ abrasions

what is the function of huge numbers of bacteria living on our skin at all times as an external barrier?

this normal bacteria provides protection, as they occupy the area making it difficult for potential pathogens to become established

what is the function of oily sebum being produced by oily glands in skin ( and sweating) as an external defence against pathogens?

the oily sebum contains substances that kill some pathogenic bacteria, and sweat secreted on skin contains salts and fatty acids that prevents the growth of many micro-organisms

what is the function of mucous membranes in the external defences against pathogens?

these body cavities that open to the exterior, secrete muus that traps particles and therfore inhibits the entry go microorganisms to the organs of the body like the digestive, urinary, and reproductive tracts.

what is the function of hairs in the external defences against pathogens?

they are found inn the nasal cavity in the nose, and the ears and the eyelashes. they trap the pathogens from proceeding and remove them.

in the nose, the mucus and the hairs trap up to what…

90% of particles inhaled when breathing

what is the function of cilia as an external defence against pathogens?

the tiny hair like projections from cells that are capable of a beating motion. The mucus membranes lining the nasal cavity, the trachea and the air passages have cilia. The beating of cilia moves mucus containing trapped particles and micro-organisms towards the throat where it may be coughed up or swallowed

what is the function of acids as an external defuse against pathogens?

stomach juices are strongly acidic, this acid kills many of the bacteria taken in with food or those contained in mucus and swallowed from the nose and windpipe. The acid kills bacteria and other micro-organisms. the vagina also has acid secretions that decrease the growth go micro-organisms, same with sweat in skin being slightly acidic

what is the function of lysozyme as an external defence against pathogens?

it is an enzyme that kills bacteria. the eyes are protected but the flushing action of tears which contains this enzyme.

what is lysozyme found in?

tears, saliva, sweat, secretions of nose and tissue fluid

what is the function of cerumen as an external defence against pathogens?

i.e ear wax. it protects the outer ear from infection by some bacteria. this is slightly acidic and contains lysozyme. it protects the ear canal from infection

how does the movement of fluid help as an external defence against pathogens?

flushing action of body fluids keeps some areas relatively free from pathogens. e,g urine through urethra- this prevents bacterial growth as it is a cleansing action to stop bacteria from flowing to bladder/ kidneys.

why do women have more bladder infections than men?

they have shorter urethras, therfore it is easier for he bacteria to reach the bladder

what are some of the flushing actions (movement of fluids)

• tears

• sweat

• saliva

• urinating

what is a reflex?

is a automatic, involuntary response to stimullus, a protective reflex help to protect the body from injury e.g blink reflex, or vomiting from an infection

what is the stimulus for sneezing?

irritation of the walls of the nasal cavity, this can be caused by harmful/ poisonous fumes, dust particles that are likely carrying micro-organisms

what is the process of sneezing?

it is the forceful expulsion of air from the lungs that carries mucus, foreign particles and irritating gases out through the nose and mouth. expelling dust, mucus and pathogens from the mouth

what is the process of coughing?

air is forced from the lungs to try and remove irritant. air carrying mucus and foreign matter (pathogens) up the trachea towards the throat and the mouth

what is the stimulus for coughing?

irritation in the lower respiratory tract (the bronchi and bronchioles)

what is the stimulus of vomitiing?

t is a physiological stimuli, excessive stretching of the stomach and bacterial toxins all induce vomitiing

what ice the process of vomiting?

is the contraction of muscles of abdomen and diaphragm not stomach, this expels pathogens from the stomach.

what is the stimulus for diarrhoea?

irritation in the small and large intestines by bacteria, viruses or protozoans

what are protozoans?

they are single celled eukaryotic micro-organisms

what is the process of having diarrhoea?

the irritation of the small and large intestines causes increases contractions of the muscles of the wall of the intestines of that the irritant is removed as quick as possible. material is to staying in the large intestines not enough for water to be absorbed, therfore the faeces are very watery. the diarrhoea is explosive contractions of smooth muscles in in the intestinal wall.

what happens when a pathogen gets past the external defences?

there are internal non-specific defences that will eliminate them. which will work against any pathogen

what are the processes of the internal non specific defences?

• natural killer cells (NKC)

• phagocytosis

• inflammation

• fever

• lymphatic system

what is a lymphocyte?

is a type of white blood cell that is a key component I the immune system.

What are natural killer cells

they are a type of white blood cell (leucocyte) that kills everything they encounter by releasing chemicals. these chemicals are called cytokines and they act as signalling molecules

what is the function of a natural killer cell?

the cytokines that they release will alert and attract other immune cells, and they secrete other chemicals to destroy cell membranes to kill unhealthy cells.

why do natural killer cells not kill healthy cells?

healthy body cells have proteins on their surface that act as “self” markers, so they dont get attacked. but virus and cancer cells have fewer markers, so they are more likely to get killed

what are phagocytes?

they are specialised white blood cells or lleucocytes, that engulf and digest micro-organisms and cell debris, eliminating pathogens before an infection has a chance to take hold

what are three types of leucocytes and what are their function?

neutrophils, eosinophils, monocytes. they are in the blood stream and can leave and enter tissues at the site of an injury or disease

what is the role of monocytes?

when a tissue becomes infected or inflamed, monocytes eave the blood stream and enter the tissue

what is the role of macrophages?

they are large phagocytic cels, some move through tissues looking for and destroying pathogens, microbes and dying cells through phagocytosis

do all macrophages wonder?

no some are fixed, and only deal with the pathogens that come to them.

how are neutrophils described?

they are described as a granulated leucocyte due to granules visible in the cytoplasm

what is the most abundant leucocyte?

neutrophils, accounting for 55-70% of all leucocytes

how are neutrophils characterised?

by a lobulated nucleus

what is the role of neutrophils?

during an infection, neutrophils are the first cells to move into the tissue to destroy the pathogen by phagocytosis. This is particularly important when killing pathogens inside cells

do neutrophils have a short life span?

yes, the die after a few days

what makes up a large portion of pus that forms after an infection?

dead neutrophil cells.

how are dendritic cells characterised?

by projections from the cytoplasm

how are dendritic cells slightly different to macrophages and neutrophils

as their function goes beyond just phagocytosis, these cells have the ability to detect, engulf and process foreign particles. They will then use this information about the ingested particles to assist with specific immunity

what is the difference between monocytes and macrophages?

When monocytes migrate into tissues, they differentiate into macrophages, which are the primary phagocytic cells in tissues.

what is the process of phagocytosis?

the phagocyte will move to the bacterium, the phagocyte will change shape so that it will completely enclose the bacterium, the lysosomes in the phagocyte contains digestive enzymes, the enzymes released will completely destroy the bacterium, then harmless particles are released from the phagocyte

words ending in -itis indicate what

inflammation, e.g inflammation of the tonsils is tonsillitis

what is inflammation?

response to tissue damage

what is the purpose of inflammation?

is to reduce the spread of any pathogens, to destroy them and to prevent the entry of any additional pathogens, remove damaged tissue and cell debris, and begin repair of damaged tissue

what are the four signs of inflammation?

• redness

• swelling

• heat

• pain

the steps in the process of inflammation is assisted by what?

proteins of the complement system

what is the complement system?

is a system of more than 20 proteins produced by the liver and macrophages that enhance the activity of antibodies and phagocytes- many of which are normally inactive

what is the process of inflammation?

• tissue damage occurs, pathogens may or may not be introduced to continue damage.

• mechanical damage or local chemical changes cause leucocytes called mast cells to be activated by complement proteins resulting in the release of histamine, Herapin, ad other chemicals into the tissue fluid. the histamine causing local capillaries to become leaky, allowing phagocytes and other leucocytes to enter. This also causes an increase in the blood flow to the area due to vasodilation so more fluid moves through capillary calls into tissue. The heparin prevents clotting of the blood.

• A clot of fluid forms around the damaged area, which slows the spread of pathogens into healthy tissues

• The complement system proteins and some chemicals released by mast cells attract phagocytes (particularly neutrophils), which are able to enter the area of damage due to the leaky dilated capillaries, they will then actively consume micro-organisms and cells debris by phagocytosis.

• the abnormal conditions inn tissues stimulate the pain receptors and therfore the person feels pain.

• phagocytes, filled with bacteria and debris and dead cells begin to die, the dead phagocytes and tissue fluid forming the puss

• Once the pathogens are cleared, mast cells and complement proteins stop messaging. local capillaries return to normal, phagocytosis ceases, new cells are produced by mitosis to repair the damaged tissue

what causes histamine and heparin release

mast cells that are activated by complement proteins

what does histamine do?

it causes local capillaries to vasodialate and become leaky, making walls of capillaries more permeable allowing phagocytes and other leucocytes to enter. This increased blood flow causes heat and redness and the escape of fluid from blood causing swelling

what does heparin do?

it prevents clotting, release of Heparin from mast cells prevents clotting in immediate area of the injury

fever is…

part of the bodys natural response to infection, to combat pathogens such as viruses or bacteria

what is the change in body temperature during a fever a result of?

resetting the body thermostat, controlled by the hypothalamus to be higher

what is the process of a fever?

after encountering an infection, white blood cells release chemicals called pyrogens during inflammatory response and act on the hypothalamus so the set point of 37 degrees is temporarily reset to a higher temperature. The hypothalamus then initiates warming responses to raise body temperature to the new temporarily set point. This can be by vasoconstriction, shivering, seeking warmth to conserve heat and driving the body temperature up rapidly until the set point is reached

what are fever causing chemicals called?

pyrogens

what is an example of a pyrogen?

interleukin- 1, produced by activated macrophages, but also produced by other cells such as dendritic or epithelial cels

what processes occur to increase the body temperature during a fever?

vasoconstriction, shivering, seeking warmth

what is the point called when a fever breaks?

its called the crisis, this is when the boys set point is returned to normal

what happens to a persons body during crisis?

the person feels hot, appears flushed, as skin vasodilation and profuse sweating take place

why does crisis take place?

this happens once the infection is dealt with and the immune system stops producing pyrogens and set point returns back to normal.

fever is beneficial…

up to a point

how can a fever be benoificaial?

• high body temperature is believed to inhibit the growth of some bacteria and viruses

• heat speeds up chemical reactions (which may help body cells repair themselves more quickly during a disease)

• fever also inhibit viral reproduction by allowing chemicals called interferons to operate more quickly

what are interferons?

any of the several proteins that are produced by cells as a defence response to viral infection. preventing the replication of the virus

what happens if body temperature goes too high for too long?

it can cause convulsions and brain damage

death will result if body temp reaches..

44.4-45.4 degrees

the lymphatic system consists of..

is network of lymph capillaries to larger lymph nodes. Lymph nodes, which are located along he length of lymph vessels

what is the main function of the lymphatic system?

to collect fluid from intracellular space that escapes from the blood capillaries and return it to the circulatory system. it is also an important part of the body’s internal defence against pathogenic organisms as the lymph nodes filter ad trap pathogens

how dos lymph move through the lymphatic system?

the lymph is moved through a series of vessels (lymph vessels) with no pump it moves the lymph through by squeezing of the skeletal muscle during body movement

what is the structure of lymph nodes?

they occur at intervals along the lymphatic vessels. each node containing masses of lymphoid tissue. they contain lymphoid follicles that contain white blood cells especially lymphocytes and macrophages. In each node there is a criss cross network of fibres which larger particles such as bacteria get trapped as the lymph flows through the spaces in the nodes. Macrophages then ingest and destroy these partilcles by phagocytosis.

what does lymph contain?

contains cell debris, foreign particles, and micro-organisms that have penetrated the body’s external defences. Some of the micro-organisms may be pathogenic, and if not destroyed could causes disease.

an example when lymph nodes get inflamed during an infection

infected finger, tenderness in armpits