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Homeostasis and Immunity Flashcards

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1
Q

What is Homeostasis?

A

is this process of the body maintaining optimum conditions, or a (fairly) constant internal environment

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2
Q

What is negative feedback?

A

the effect reduces or eliminates the stimulus.

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3
Q

What is Positive feedback?

A

the response to a stimulus reinforces and intensifies the stimulus.

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4
Q

What is the form of sugar in diff parts of the body?

A

In the blood - Glucose
In liver + muscle cells - glucose converted to GLYCOGEN

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5
Q

What is Glycogenesis and what hormone stimulates it?

A

Formation of glycogen from other carbohydrates (E.g. glucose)
- stimulated by insulin

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6
Q

What is Glycogenolysis and what hormone stimulates it?

A

Breakdown of glycogen to glucose
- stimulated by glucagon

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7
Q

What is Gluconeogenesis?

A

Conversion of fats or proteins into glucose

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8
Q

What are the 2 neg feedback loops when there is an increase in BGL?

A

Receptor: stimulates beta cells(pancreas)
Message: cells secrete insulin
Modulator: targets liver
Message: liver stimulates glycogensis
Effector: more glucose is stored in the liver
Response: less glucose released in blood
Feedback: decrease of blood glucose lvls

Receptor: stimulates beta cells(pancreas)
Message:cells secrete insulin
Modulator: targets body cells
Message: stimulates uptake of glucose
Effector: more glucose used in cell rep
Response: less glucose released in blood
Feedback: decrease of blood glucose

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9
Q

What are the 2 neg feedback loops when there is an decrease in BGL AND the receptor is alpha cells?

A

Message: Cells secrete glucagon
Modulator: targets liver
Message: stimulates glycogenolysis
Effector: glycogen converted to glucose in liver
Response: more glucose released into blood
Feedback: increase blood glucose

Message: Cell secrete glucagon
Modulator: targets liver
Message: stimulates gluconeogenesis
Effector: new gluc molecules produced
Response: more glucose released
Feedback: increase BG

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10
Q

What are the 2 neg feedback loops when there is an decrease in BGL AND the receptor is adrenal glands?

A

Receptor: Stimulates medulla
Message: secrete adrenaline + noradrenaline
Modulator: targets liver
Message: to simulate glycogenolysis
- increase of BG

Receptor: Stimulates cortex
Message: secrete cortisol
Modulator: targets liver
Message: stimulate glycogenolysis and gluconeogenesis
- increase of BG

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11
Q

What is thermoregulation?

A

the process of maintaining the balance between heat production and heat loss.
- Heat produced by metabolic activity – during strenuous activity, body produces more heat than needed and must be removed.

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12
Q

What are the 2 neg feedback loops when there is an increase of body temp?

A

Receptor: stimulates thermoreceptors in hypothalamus
Message: sends nerve impulse from CNS
Modulator: to PNS
Message: Pns sends nerve impulse from sympathetic division of ANS to sweat glands
Effector: sweat glands contract to pump sweat to surface
Response: evaporation of sweat from skin
Feedback: Decrease of Body temp

Receptor: stimulates thermoreceptors in hypothalamus
Message: sends nerve impulse from CNS
Modulator: to PNS
Message: Pns sends nerve impulse from parasympathetic division of ANS to blood capillaries
Effector: causes vasodilation of blood capillaries
Response: more blood transported to capillaries in the skin
Feedback: decrease of body temp

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13
Q

What are the 2 neg feedback loops when there is a decrease of body temp?

A

Receptor: stimulates thermoreceptors in hypothalamus
Message: sends nerve impulse from CNS
Modulator: to PNS
Message: Pns sends nerve impulse from sympathetic division of ANS
Effector: to skeletal muscles
Response: causes shivering - rhythmic muscle tremors releasing heat
Feedback: increase body temp

Receptor: stimulates thermoreceptors in hypothalamus
Message: sends nerve impulse from CNS
Modulator: to PNS
Message: Pns sends nerve impulse from sympathetic division of ANS to blood capillaries
Effector: vasoconstriction of blood capillaries
Response: less blood transported to capillaries in skin
Feedback: increase of body temp

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14
Q

Behavioural responses and metaboic rate of increase in body temp

A
  • turning on fan/AC, removing clothing, reducing physical activity.
  • ↓ production of thyroxine = ↓ heat produced. Occurs in summer.
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15
Q

Definition of vasoconstriction?

A

a decrease in the diameter of arterioles, restricting the flow of blood through them
- Results in ↓ flow of warm blood to skin
- ↓ transfer of heat to skin and skin becoming cooler, and less heat lost from body surface.

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16
Q

Definition of vasodilation?

A

an increase in the diameter of arterioles, increasing the flow of blood through them
- ↑ heat loss through radiation and convection. Skin becomes reddish and surface temperature ↑.

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17
Q

What are the 2 neg feedback loops when there is a decrease in body fluid levels?

A

Stimulus: decreased amount of water(osmotic pressure is raised)
Receptor: stimulates osmoreceptors in hypo
Message: sends nerve impulse
Modulator: to posterior lobe of pituitary gland
Message: release ADH
Effector: stimulates nephron tubules in kidneys
Response: to increase the permeability of DCT and collecting ducts so more water reabsorbed
Feedback: increased water conc in plasma(osmotic pressure falls)

Stimulus: decreased amount of water(osmotic pressure is raised)
Receptor: stimulates osmoreceptors in hypo
Message: sends nerve impulse
Modulator: to thirst centre in hypo
Message: results in conscious feeling of thirst
Effector: results in having a drink
Response: and fluid consumed is absorbed in plasma from alimentary canal
Feedback: increased water conc in plasma(osmotic pressure falls)

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18
Q

What is the neg feedback loop when there is a increase in gas concentrations?

A

Stimulus: increase in co2(Increase in H+ conc)
Receptor:stimulates central chemoreceptors(medulla) + peirpoheral chemorecep (carotid + aortic bodies)
Mesage: sends nerve impulse
Modulator: to respiratory centre in medula
Message: sends nerve impulse
Effector: to respiratory muscles
Response: results in increase in breathing rate
Feedback: decrease in Co2(decrease in H+ conc)

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19
Q

What is the neg feedback loop when there is a decrease in gas concentrations?

A

Stimulus: decrease in O2
Receptor: stimulates peripheral chemorecep (carotid + aortic bodies)
Message: sends nerve impulse
Modulator: to respiratory centre in medula
Message: sends nerve impulse
Effector: to respiratory muscles
Response: results in increase in breathing rate
Feedback: increase in O2

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20
Q

What is a communicable disease?

A

caused by foreign organisms invading the body and multiplying there.
- infectious, transmissible

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21
Q

How can a contagious disease be spread?

A
  • Passed on by contact with infected person, or something they’ve touched.
  • Or via a vector, an intermediate host (E.g. mosquito).
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22
Q

What is a pathogen?

A

Disease-causing organisms

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23
Q

What are the 4 types of pathogens?

A

Bacteria, virsues, fungi, parasites

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24
Q

What is bacteria? examples

A

prokaryote, unicellular, organisms with a simple internal strucutre
- lack a nucleus
- Most are non-pathogenic
- Rapid multiplication can crowd and disrupt/kill cells/tissue.
- They can also secrete toxins which damage/kill cells.
- Classified by cell shape
- eg. chlamydia, gastro, pneumonia, syphillis

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25
Q

What is viruses? examples

A

an infectious agent, too small to be seen with a light microscope, not living
- Contain DNA or RNA surrounded by protein coat (capsid).
- Viruses cannot reproduce by themselves
-eg. HIV/AIDS, colds, herpes, influenza, small pox

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26
Q

Describe how virus infect

A
  • they infect a living cell and its DNA or RNA induces the host cell to manufacture more virus particles
  • Killing of cells/disruption to regular cellular activity is what causes symptoms of illness.
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27
Q

What is Non enveloped and enveloped virus

A

enveloped viruses have additional envelope of lipid-protein molecules

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28
Q

Examples of fungi

A

Ringworm
Thrush
Tinea

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29
Q

examples of animal parasties

A

malaria, tapeworms, lice, ticks, scabies

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30
Q

Describe COVID-19

A
  • Caused by virus strain SARS-CoV-2 (Severe acute respiratory syndrome-related coronavirus 2)
  • Enveloped
  • Possesses large single-strand RNA genome
  • Spike glycoprotein (S) is main inducer of neutralising antibodies (antigen) – also current focus for vaccine.
  • Other coronaviruses: Common cold, SARS.
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31
Q

What are bacteriophages?

A

viruses using bacteria as hosts.

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32
Q

Name the 6 modes of transmission of pathogens?

A
  • Transmission by contact
  • Transmission by body fluids
  • Infection by droplets
  • Ingestion
  • Airborne transmission
  • Transmission by vectors
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33
Q

What is transmission by contact and examples?

A
  • Spread of pathogen by contact (e.g. skin infections + STIs):
  • Direct: touching an infected person
  • Indirect: touching an object that an infected person touched.
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34
Q

What is Transmission by body fluids and examples?

A
  • Pathogen enters when body fluids of infected person come into contact with mucous membranes (e.g. mouth, nose, throat, genitals) or blood (e.g. needle, break in skin) of uninfected person.
    eg HIV, Hep B + C
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35
Q

What is Infection by droplets and examples?

A
  • Tiny droplets containing virus can be emitted when talking, breathing, sneezing, coughing.
  • They are breathed in by others or settle on food/utensils and ingested later.
    eg, Colds, Influenza, COVID-19
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36
Q

What is Ingestion and examples?

A

Food or drink contaminated with pathogen consumed.
eg Salmonella

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37
Q

What is Airborne transmission and examples?

A
  • Most bacteria killed when exhaled moisture droplet evaporates, but viruses and some bacteria can remain viable and cause infection when inhaled.
  • Viable for greater distance than droplets.
    eg Tuberculosis, COVID-19
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38
Q

What is transmission by vectors and examples?

A
  • Transfer of pathogens by other animals, such as insects.
  • Some vectors transfer the pathogen directly (e.g. house flies), many vector-borne diseases require specific pathogen (e.g. malaria + dengue fever spread by mosquitos).
    eg Malaria, Dengue fever
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39
Q

What is defence against disease?

A

Defence mechanisms protect against invasion by pathogenic micro organisms.
- They can be specific or non-specific

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40
Q

What is non specfic defence agaisnt disease?

A
  • Innate Immune System
  • Work against all pathogens
  • Body’s first line of defence.
    Includes:
  • External defences
  • Phagocytosis
  • Inflammation
  • Fever
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41
Q

What is specfic defence agaisnt disease?

A
  • Adaptive/ Acquired Immune System
  • Directed at a particular pathogen
  • E.g. After becoming infected with chickenpox, body produces antibodies which are only effective against chickenpox virus.
    Includes:
  • Humoral/antibody-mediated response
  • Cell-mediated response
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42
Q

What is 7 EXTERNAL non specific defence?

A

Skin
Mucous membranes
Hairs+cilia
acids
lysozyome
cerumen
flushing action

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43
Q

What is the external non specific defence: skin?

A
  • Barrier stopping micro-organisms entering body.
  • Oily secretion (sebum) from oil glands and sweat from sweat glands also prevent micro-organism growth.
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44
Q

What is the external non specific defence: mucous membranes?

A
  • line exterior body cavities.
  • Secrete mucus to inhibit micro-organism entry.
  • found in mouth, anus
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45
Q

What is the external non specific defence: hairs+cilia?

A
  • Hairs in ears + nose trap particles.
  • Cilia move mucus containing trapped particles + micro-organisms towards throat to be coughed up.
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46
Q

What is the external non specific defence: acids?

A
  • Secretions from stomach, vagina + sweat kill bacteria/ inhibit growth of pathogens.
  • Stomach acid very effective - kill many micro-organisms.
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47
Q

What is the external non specific defence: Lysozyme?

A

Enzyme that kills bacteria – found in eyes/tears, saliva, sweat, nasal secretions + tissue fluid.

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48
Q

What is the external non specific defence: Cerumen?

A
  • Ear wax - Slightly acid + contains lysozyme which kill bacteria
  • Protects outer ear from infection
  • inhibits bacterial growth
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49
Q

What is the external non specific defence: Flushing action?

A
  • Helps to cleanse pathogens.
  • Urine flow through urethra helps to stop bacteria reaching bladder/kidney.
  • eyes cleansed by tears containing chemical inhibiting bacterial growth
  • mouth cleansed by saliva
  • Also tears, sweat + saliva.
50
Q

What 3 types of phagocytes (internal non specific defence- Phagocytosis)

A
  1. Macrophages
  2. Neutrophils
  3. Dendritic cells
51
Q

Def of phagocytes

A

White blood cells that can engulf and digest (destroy) micro-organisms to eliminate pathogens before infection progresses.

52
Q

What is the definition of NON-SPECIFIC DEFENCE INTERNALInflammation, its purpose and 4 signs?

A
  • response to any damage to tissues.
  • Occurs as a series of integrated steps.
  • Purpose:
  • Reduce spread of pathogens, to destroy them and to prevent entry of additional pathogens.
  • Remove damaged tissues/cell debris
  • Begin repair of damaged tissue.
  • Four signs of inflammation: redness, swelling, heat and pain.
53
Q

first 3 steps to inflammatory response?

A
  1. Mast cells (present in most tissues), when stimulated by mechanical damage (e.g. cut) or local chemical changes, release histamine, heparin and other chemicals (e.g. chemokines).
  2. Histamine increases blood flow through area (vasodilation) and making blood vessel walls more permeable so more fluid moves into tissue. - redness+heat
  3. Heparin from mast cells prevents clotting in immediate area so clot forms around damage instead preventing spread of pathogens. - swelling
54
Q

last 4 steps to inflammatory response?

A
  1. Chemicals released by mast cells attract phagocytes (particularly neutrophils) which consume micro-organisms + debris by phagocytosis.
    5.Abnormal conditions in tissue stimulate pain receptors (person feels pain) in the area.
    6.Phagocytes filled with bacteria + debris die forming pus.
    7.New cells produced by mitosis and damaged tissue repaired
55
Q

NON-SPECIFIC DEFENCE: INTERNALFever. Describe

A
  • Elevated body temperature (fever) can occur during infection.
  • Due to chemicals called pyrogens which are released by WBCs (e.g. interleukin-1 produced by macrophages) during inflammatory response which act on hypothalamus.
  • Body temperature still regulated in response to heat/cold but the ‘set point’ is reset by the hypothalamus.
56
Q

What are the 3 benefits and danger of a fever?

A

Benefits:
- High body temperature believed to inhibit growth of some bacteria/viruses
- Speeds up chemical reactions (body cells can repair more quickly).
- May inhibit viral replication by allowing chemicals called interferons to operate more quickly.

Dangers:
- Death will occur if body temp reaches ~44.5ºC.

57
Q

NON-SPECIFIC DEFENCE: INTERNALLymphatic System. What does it consist of?

A
  • Network of lymph capillaries joined to larger lymph vessels
  • Lymph nodes, located along some lymph vessels.
58
Q

What are the 2 functions of lymphatic system

A
  • Collect fluid escaping from blood capillaries and return to circulatory system

Internal defence against micro-organisms:
- Lymph nodes contain network/mesh of lymphoid tissue which enables macrophages to trap + destroy destroy micro-organisms more easily (~10-30 mins)
- Lymphocyte formation increases when infection occurs, causing swollen and sore lymph nodes.

59
Q

What is the immune response and the two types?

A
  • The immune response is a homeostatic mechanism that helps deal with invasion and restoration of normal internal environment.
    Two parts:
  • Antibody-mediated Immunity
    (Humoral Response)
  • Cell-mediated Immunity
    Both contribute to specific or acquired immunity
60
Q

What is the Antibody-mediated Immunity
(Humoral Response), antigen type and main cell type involved?

A
  • Involves production + release of antibodies into blood + lymph which circulate + attack invaders.
  • Provides resistance to viruses, bacteria + bacterial toxins before they enter the body’s cells.
  • antigen type: Eliminates extracellular antigens
  • Main cell type involved: B-lymphocytes (produced + mature in bone marrow)
61
Q

What is Cell-mediated immunity?antigen type? main cell type involved?

A
  • Involves formation of special lymphocytes that destroy invaders
  • Provides resistance to the intracellular phase of bacterial and viral infections.
  • works against cells infected by virus, bacteria, fungi and parasites.
  • antigen type: Eliminates intracellular antigen
  • Main cell type involved:
    T-lymphocytes (produce in bone marrow + mature in thymus)
62
Q

describe B-cells

A

B-lymphocytes:
- Active in Humoral/ Antibody-mediated immunity
- Chemical-based system (i.e. antibodies)
- B-cells mainly become plasma cells which produce + release antibodies
- Antibodies combine with antigen to inactivate/destroy it.
- Effective against extracellular bacteria (and some viruses)

63
Q

Describe T-cells

A

T-lymphocytes:
- Active in Cellular/Cell-mediated immunity
- Cell-based system
- T-cells mainly become killer T-cells and helper T-cells.
- Killer T-cells destroy antigens
- Helper T-cells promote macrophage phagocytosis
- Effective against intracellular viruses
+ cancer cells (and some bacteria)

64
Q

What are antigens?

A
  • Any substance capable of causing a specific immune response (antibody or cell mediated).
  • Presence triggers both types of immune responses.

Can be: (Although, not always associated with micro-organisms)
- Whole virus particle
- Bacterial cell, or part of bacterium (e.g. flagella)
- Toxin produced by bacteria

65
Q

What are self antigens?

A
  • those produced by own body – do not trigger immune response.
  • Immune system programmed to distinguish from non-self (foreign) antigens from birth.
66
Q

What are anti bodies?

A
  • Y-shaped specialised proteins (immunoglobulins) produced in response to a non-self antigen by plasma cells.
  • Antibodies combine with the antigen, for which they are specific to, to form an antigen-antibody complex
  • Each antibody can only combine with one particular antigen.
  • The shape of the antibody is the same as the shape of the B-cell receptor which detects/becomes activated by the antigen.
67
Q

How do antibodies work? PLANC

A
  • Antibody responses vary depending on the antigen and can include:
  • Precipitation: Bind to soluble antigens to make insoluble*
  • Lysis: dissolves organisms
  • Agglutination: causes clumping together of bacteria/viruses/foreign cells *
  • Neutralisation: Inhibit foreign enzymes/bacterial toxins by combining with them or inhibiting their reaction with other cells.
    ↪ Binds to virus surface to prevent entry to cells *
  • Coat: surface of bacteria*
    *= allows phagocytes to consume invaders more easily
68
Q

Describe the 4 steps in Anti body mediated immunity process

A
  1. Thousands of B-cells in lymphoid tissue with different types of receptors for particular antigens.
    ↪B-cells activated when presented with antigen by APCs.
    ↪Cytokines from Helper-T-cells also activate B-cells.
  2. B-cell enlarges and divides to form groups of cells called clones
  3. Most clones become plasma cells which secrete the specific antibody capable of attaching to antigen. ↪Antibodies circulate in blood, lymph + extracellular fluid to reach site of invasion.
    ↪Can take days for antibody levels to build up during primary response.
  4. Some b-cells become memory cells.
    ↪ Spread to all tissues to allow more rapid secondary response (plasma cells able to form more quickly + antibody levels rise rapidly) if exposure occurs again.
69
Q

What are the antigen-presenting cells and its function?

A
  • Macrophages, dendritic cells and B lymphocytes
  • They engulf foreign materials/pathogens + digest them before displaying the antigen on the surface of their cell membrane.
  • then present the antigen to T lymphocytes to sensitise and activate them, stimulating them to divide into clones (clonal selection).
70
Q

What are 4 protective reflexes?

A
  • Help protect the body from injury and protect against infection:
    1. Sneezing
    2. Coughing
    3. Vomiting
    4. Diarrhoea:
71
Q

What are the 2 cells involved in adaptive immunity?

A

lymphocytes and macrophages

72
Q

What are the 3 lymphocytes, where are they produced and what responses are they involved in?

A
  • B-lymphocytes, T-lymphocytes + natural killer (NK) cells.
  • Produce in bone marrow (mostly)/ lymphoid tissue and ‘roam’ through body in tissue + blood.
    Involved in non-specific + specific responses :
  • Non-specific: NK cells – attach to virus affected cells + cause apoptosis.
    Specific: B-lymphocytes and T-lymphocytes
73
Q

What are macrophages? and what responses are they involved in?

A
  • Large phagocytotic cells that develop from monocytes (WBC).
    Involved in non-specific + specific responses :
  • Non-specific: consume foreign substance/ micro-organisms.
  • Specific: Alert adaptive immune system to presence of foreign material.
74
Q

Explain clone selection of lymphocytes

A
  • Antigen presenting cells (dendritic cells or macrophages) phagocytise a bacterium + then move fragments of antigen to their surface.
  • Helper T-cells can recognise the antigen, become sensitised/activated and secrete cytokines (e.g. interleukin) which stimulate B-cells with the same receptor to enlarge + divide to produce clones.
75
Q

Describe 4 steps into the cell-mediated immunity process

A
  • Macrophages (or B-cells) encounter a foreign antigen, travel to lymphoid tissue and present to T-cells which corresponds to the antigen.
  • After this, T-cells that are specifically programmed for the specific antigen become activated, or sensitised.
  • They enlarge, divide and form clone cells.
  • Some clone T-cells become memory cells, the others become 1 of 3 different types: Killer t-cells, helper t cells or suppressor t-cells
76
Q

What are killer t-cells?

A

(Cytotoxic)
- Migrate to site of infection, attach to invading cells + secrete substance to destroy before going in search of more antigens.

77
Q

What are helper t-cells?

A
  • Important in humoral + cell response. Secrete substances that:
  • Cause lymphocytes at infection site to become sensitised, intensifying response.
  • Attract macrophages (by cytokine secretion) + intensify their phagocytic activity.
78
Q

what are supressor t-cells?

A
  • Act when infection dealt with/ immune response becomes too excessive.
  • Release substance to inhibit T/B-cells + slow immune activity.
79
Q

Explain the primary immune response

A
  • response to first exposure
  • Takes 2 weeks to reach peak antibody levels which then decline.
  • B-cells need to multiply differentiate to plasma cells then produce antibodies.
  • Leaves immune system with memory cells.
80
Q

Explain the secondary immune response

A
  • due to exposure to the same antigen.
  • Antibody levels rise faster, reach higher conc. + remain elevated for longer.
  • Antigen usually unable to have any noticeable effects/no illness results.
81
Q

Def of immunity?

A

Immunity is the resistance to infection caused by a particular pathogen/micro-organism.

82
Q

What is Natural immunity?

A

Normal exposure to antibodies or antigen

83
Q

What is Artificial immunity?

A

A person is deliberately given an antigen or antibodies

84
Q

What is Passive immunity?

A
  • A person receives antibodies.
  • Protection immediate but temporary - no immune response
85
Q

What is active immunity?

A
  • A person produces antibodies after antigen exposure.
  • Protection slow to develop but long lasting - immune response occurs
86
Q

What is passive natural immunity?

A

Antibodies enter the bloodstream across the placenta or in breast milk

87
Q

What is Passive artificial immunity?

A

Antibodies injected into the bloodstream.

88
Q

What is Active natural immunity?

A

Ability to manufacture antibodies results from an attack of a disease

89
Q

what is active artificial immunity?

A

Ability to manufacture antibodies results from being given an antigen by vaccination

90
Q

Def of immunisation

A
  • the programming of immune system so body can rapidly respond to infection.
  • This can occur through vaccination
91
Q

Def of vaccination

A

the artificial introduction of antigen (vaccine) to give ability to produce appropriate antibodies without suffering disease.

92
Q

4 types of vaccines?

A
  • Live attenuated micro-organisms
  • Dead micro-organisms
  • Toxoids
  • Sub-unit
93
Q

Describe Live attenuated micro-organisms and what it protects against

A
  • Contains living attenuated (reduce virulence/ability to produce symptoms) micro-organisms.
  • protects against Measles, mumps, rubella, rabies, polio, TB, yellow fever
94
Q

Describe Dead micro-organisms and what it protects against

A
  • Contains dead micro-organisms.
  • Immunity not a prolonged as live attenuated vaccines.
  • protects against Cholera, bubonic plague, typhoid, whooping cough, influenza, Hep A
95
Q

Describe toxoids and what it protects against

A
  • Made from filtrates of bacterial cultures containing inactivated toxins (toxoids).
  • Used in cases where bacteria use toxins to produce effects.
  • protects against Diphtheria, tetanus
96
Q

Describe Sub-unit
and what it protects against

A
  • Fragment of organism used to evoke response
  • protects against HPV, Hep B
97
Q

What are 3 ways to deliver a vaccination?

A
  • Injection – most commonly used method.
  • Oral – E.g. one type of Polio vaccine.
  • Potential/future options: nasal spray, in food, skin patches.
98
Q

What are the risks of vaccines?

A
  • All undergo significant testing phases + TGA approval, but still risk of side effects.
    ↪Allergic reaction is main risk. E.g. Many flu vax made in fertilised eggs, some Hep B vaccinations contain yeast.
    ↪No conclusive evidence linking vaccines to any disorders.
  • Development of alternative approaches:
    ↪Modification of pathogen by changes to DNA (make less virulent)
    ↪Insertion of DNA sequences into harmless bacterial cells (recombinant DNA) to induce production of antigens.
99
Q

Why do most vaccination commence after baby is 2months old?

A
  • Immune system need time to become activated.
  • Prior, reliant on antibodies from mother via placenta or breast milk
100
Q

What are 3 ethical concerns on the use of vaccinations?

A
  • animal treatment
  • testing
  • risk
101
Q

What do immunisation programs rely on?

A
  • majority participation + herd immunity to prevent outbreaks.
102
Q

What are antibiotics?

A
  • Treat bacterial infections – one of most prescribed drugs.
  • Penicillin (produced from mould) discovery stimulated search for more antibiotic substances.
  • Streptomycin produced by bacteria and Cephalosporin produced by fungi.
  • Broad-spectrum (effective against many) or narrow-spectrum (effective against specific bacteria).
103
Q

What are two types of antibiotics? and explain

A
  • Bactericidal: Change structure of cell wall/membrane or disrupt essential enzymes
  • Bacteriostatic: Stop bacteria reproducing, usually by disrupting protein synthesis.
104
Q

What are antivirals and examples?

A
  • Specifically used for treating viral infections (antibiotics ineffective).
  • The way viruses replicate (DNA/RNA inducing host to replicate) it makes difficult to find/create antivirals – interfering with viral replication likely to also affect host.
  • Most available antivirals treat HIV, Herpes (Zovirax®), Hep B and C and Influenza A and B (Tamiflu®).
105
Q

Why are boosters important?

A
  • Boosters (second vaccination) required to stimulate secondary response.
  • Memory cells react quickly resulting in higher, longer-lasting level of antibodies in addition to more memory cells.
  • Timing of booster is important – too early will result in existing antibodies in blood eliminating vaccine content before B-cell activation.
106
Q

What is sneezing?

A

Stimulated by irritation of nasal cavity such as fumes + dust particle (likely to carry pathogen).
↪Forceful expulsion of air from lungs causes mucus, foreign particles + irritating gases out.

107
Q

What is Coughing?

A

Stimulated by irritation to lower respiratory tract (bronchi + bronchioles).
↪ Air forced from lungs as with sneezing.

108
Q

What is vomiting?

A

Can be induced by psychological stimuli, excessive stretching of stomach + bacterial toxins.
↪Abdomen + diaphragm (not stomach) contract to expel stomach contents.

109
Q

What is diarrhoea?

A

Irritation of small/large intestines by bacteria, virus or protozoans increases contractions of intestinal muscles so irritant removed quickly.
↪Material doesn’t have time for water to be absorbed.

110
Q

What are macrophages?

A
  • Some migrate through tissue ‘looking’ for pathogens, others are fixed and deal with pathogens that come to them.
111
Q

What are Neutrophils?

A
  • Short life span
  • Most abundant WBC and first cells to move into infected area.
112
Q

What are dendritic cells?

A
  • Projections from cytoplasm
  • Have ability to detect, engulf and process foreign particles to assist with specific immunity.
113
Q

5 Components of a negative feedback loop

A
  • Stimulus – change in environment
  • Receptor – detects change
  • Modulator – control centre; processes information received from receptor and sends information to effector.
  • Effector – carries out response
  • Feedback – original stimulus changed by response.
114
Q

What is dehydration?

A
  • water loss exceeds water intake.
  • Symptoms noticeable when person loses ~2% of normal body water.
  • E.g. severe thirst, low blood pressure, dizziness, headache.
  • Can occur due to sweating, vomiting, or diarrhoea.
115
Q

What is water intoxication?

A
  • (water poisoning): too much water in the body.
  • Body fluids become diluted and cells take in extra water by osmosis.
  • Can occur when person loses lots of water + salts from sweating and replaces only with plain water.
  • Symptoms: lightheadedness, headache, vomiting, collapse.
116
Q

What is tolerance limits?

A

are the upper and lower limits where cells can still function
- max and min limits the body can take when there is a change in internal environment

117
Q

What is gene therapy?

A
  • aims to treat or cure genetic abnormalities by identifying faulty genes and inserting healthy ones
  • potential to treat underlying cause
  • can treat typ1 diabetes, cystic fibrosis, Huntington disease
118
Q

Describe the process of gene therapy

A
  • involves using a viral vector
  • a functional gene inserted into vector
  • virus replicates inside host cell
  • creates many copies of functional gene inside body
  • can create functioning insulin
119
Q
A
120
Q

What is cell replacement therapy?

A
  • can help disorders involving loss of, or injury to, normal cells
  • Cloning and differentiation of stem cells is used to make specific cell type or tissue type in vitro
  • Cloned tissue inserted into an individual to replace damaged or lost tissue in the affected individual
120
Q

What is recombinant DNA?

A
  • made by combining fragments of DNA from different sources.
  • involves artificially changing DNA
  • potential for replacing faulty genes with healthy ones.
  • organism produced is a genetically modified organism (GMO)
  • rDNA used in gene therapy
120
Q

The 8 steps of recombinant DNA

A
  • isolate gene of interest
  • cut out gene of interest using restriction enzymes
  • remove plasmid from bacterium
  • cut open plasmid using the same restriction enzymes
  • insert gene of interest into plasmid using DNA ligase
  • ligase joins sticky ends of plasmid to sticky ends of isolated gene
  • New recombinant vector inserted into host cell
  • Host replicates, replicating the plasmid as well.

Human Biology (6 decks)

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