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AS Level Biology > 10. IMMUNITY > Flashcards

10. IMMUNITY Flashcards

1
Q

All macrophages and neutrophils arise from a stem cell called the

A

haematopoietic stem cell

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2
Q

What are granules in neutrophils

A

secretory vesicles

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3
Q

The cytoplasm of a neutrophil contains vacuoles full of

A

hydrolytic enzymes

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4
Q

What removes dead cells in the body

A

Phagocytes (have lysosomes and vacuoles with hydrolytic enzymes)

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5
Q

Why is it hard to develop a vaccine for malaria

A
  • several causative species
  • has many antigens as it is eukaryotic
  • different antigens in different stages of life
  • mutations change antigens/antigenic mutation/variation
  • antigenic concealment
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6
Q

Why would a vaccination programme be unsuccesful

A
  • not able to achieve herd immunity
  • lack of willingness of people to get vaccinated
  • lack of trained people to vaccinate
  • poor immune response
  • only trial programmes
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7
Q

How are monoclonal antibodies made by hybridomas

A
  • protein injected into mouse and time given for immune response to occur
  • plasma cells extracted from mouse spleen and fused with cancer cells forming hybridoma cells
  • cells are separated and cultured in individual wells
  • screened for cells producing desired antibody and grown in large cell culture
  • antibodies produced can be humanised
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8
Q

Why do we suffer repeated infections of influenza or the common cold

A
  • because there are many different strains of viruses that cause these diseases
  • each with having different antigens
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9
Q

Neutrophils (granulocytes)

A
  • phagocytes
  • form 60% of the white cells in the blood (most common)
  • travel throughout the body, often leaving blood by squeezing through gaps in the walls of the capillaries
  • are released in large numbers from their stores in the bone marrow during an infection
  • short-lived cells
  • contain many lysosomes/vesicles
  • number of neutrophils in the blood increase during bacterial infections and when cells become inflamed and die
  • smaller than macrophages/monocytes
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10
Q

Macrophages (agranulocytes)

A
  • phagocytes
  • larger than neutrophils
  • tend to be found in organs such as the lungs, liver, kidneys, spleen and lymph nodes, rather than remaining in the blood
  • travel in the blood as monocytes, which develop into macrophages once they leave the blood and settle in organs, removing any foreign matter found there
  • long-lived cells
  • play a crucial role in initiating immune responses as they act as APCs
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11
Q

What is histamine

A
  • when pathogens invade the body, some of the body’s cells under attack respond by releasing histamine
  • plays a role in chemotaxis
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12
Q

What is chemotaxis

A

movement towards a chemical stimulus such as histamine or other chemicals released by pathogens when they invade the body is called chemotaxis

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13
Q

Plasma cells

A
  • produced by B lymphocytes
  • make antibodies
  • contain large network of rough endoplasmic reticulum for the production of antibody molecules (protein synthesis)
  • contain many mitochondria to provide ATP for protein synthesis and the movement of secretory vesicles
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14
Q

Why are several antibiotics taken

A
  • bacteria likely to be resistant to one antibiotic

- bacteria less likely to be resistant to all antibiotics

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15
Q

Why are antibiotics taken over a long period of time

A
  • bacteria are inside cells where they are protected from antibiotics
  • bacteria grow/divide slowly
  • ensures all bacteria are killed, otherwise they remain
  • prevents development of antibiotic resistance
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16
Q

What causes difference in blood groups

A
  • glycolipid antigens on red blood cells
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17
Q

Functions of cytokines

A
  • stimulate appropriate B cells to divide by mitosis, differentiate into plasma cells, and secrete antibodies
  • stimulate macrophages to carry out phagocytosis more vigorously
  • stimulate appropriate killer T cells to divide by mitosis and differentiate by producing vacuoles full of toxins
18
Q

What does the interaction between acetylcholine and its receptors do

A
  • it stimulates channels to open allowing sodium ions to move through the membranes
  • the influx of sodium ions begin a series of events that result in muscle contraction
19
Q

How is myasthenia gravis an autoimmune disease

A
  • people with MG have helper T cells specific for the cell surface receptors for acetylcholine
  • these cells stimulate a clone of B cells to divide and differentiate into plasma cells and secrete antibodies
  • which bind to the receptor blocking the transmission of impulses from motor neurones
20
Q

What happens to muscle cells without receptors for acetylcholine

A
  • muscle cells are not stimulated

- without any stimulation, muscle tissue starts to break down

21
Q

Symptoms of myasthenia gravis

A
  • muscle weakness that gets worse with activity and improves with rest
  • drooping eyelids are an early symptom
22
Q

Why are drooping eyelids one of the first symptoms of MG

A

these muscles are in constant use and tire quickly

23
Q

Treatments for myasthenia gravis

A
  • a drug that inhibits the enzyme in synapses that breaks down acetylcholine
  • this increases the concentration of acetylcholine in synapses so its action in stimulating muscle fibers to contract lasts for longer
  • surgical removal of the thymus gland
  • because it is the site of maturation of the helper T cells that stimulate B cells to produce antibodies to the acetylcholine receptors
24
Q

Names of autoimmune diseases

A

myasthenia gravis
multiple sclerosis
rheumatoid arthritis
type-I diabetes

25
Q

What happens in multiple sclerosis

A
  • nerve cells in the brain and spinal cord lose the insulating myelin sheaths that surround them
  • can happen anywhere in the CNS and appears to be quite random
  • degenerating areas, known as plaques, can be detected using MRI scans
  • with the loss of the protective myelin, the neurones stop conducting impulses
  • and there is a loss of the functions controlled by the areas of the CNS concerned
26
Q

Symptoms of multiple sclerosis

A
  • muscle weakness
  • loss of sensory output from the skin and other areas
  • poor vision
  • mental problems
27
Q

What is rheumatoid arthritis

A
  • starts with the finger and hand joints and spreads to the shoulders and other joints
  • tendons become inflamed and there is constant muscle spasm and pain
  • people with rheumatoid arthritis find it hard to keep mobile
28
Q

What is type 1 insulin-dependent diabetes

A
  • caused partly by a virus infection that makes the cells that secrete insulin in the pancreas unrecognisable as self
  • killer T cells enter the islets of Langherhans and destroy the cells that produce insulin
29
Q

Why do some autoimmune diseases like myasthenia gravis run in families

A
  • it is not an inherited condition
  • people with certain alleles of genes involved in cell recognition are at a higher risk of developing MG than those without those alleles
  • susceptibility to the diseases is inherited
30
Q

Why are antibodies desirable in the treatment and diagnosis of disease

A

they are very specific

31
Q

What is the problem in making monoclonal antibodies

A
  • B cells that divide by mitosis do not produce antibodies

- plasma cells that produce antibodies do not divide by mitosis

32
Q

How are radioactively labelled antibodies made

A

a radioactive chemical that produces gamma radiation is attached to each antibody molecule

33
Q

How are radioactively labelled antibodies used in diagnosis

A
  • can be used to locate the position of blood clots in the body of a person thought to have deep vein thrombosis
  • labelled antibodies are introduced into the patient’s blood
  • as the antifibrin Mabs are carried around the body, they bind to any fibrin molecules with which they come into contact
  • a gamma-ray camera is used to detect the radioactivity emitted by the labelled antibodies and locate their exact position
  • the position of the labelled Mabs indicates the position of any blood clots
34
Q

How are Mabs humanised so they can be used in treatment

A
  • altering the genes that code for the light and heavy chains of amino acids so that they code for human sequences of amino acids, rather than mouse or rabbit sequences
  • changing the type and position of the sugar groups that are attached to the heavy chains to the arrangement found in human antibodies
35
Q

What can be diagnosed by monoclonal antibodies

A
  • location of blood clots in a person thought to have deep vein thrombosis: antifibrin antibodies bind to fibrin which is the main protein found in blood clots
  • locate cancer cells: cancer cells have proteins in their cell surface membranes that differ from the proteins on normal blood cells and can therefore be detected by antibodies
  • identify the exact strain of a virus or bacterium that is causing an infection: this speeds up the choice of the most appropriate treatment for the patient
  • blood typing for transfusion
  • tissue typing before transplants
36
Q

Advantages of using monoclonal antibodies in diagnosis

A
  • monoclonal antibodies used all have the same specificity
  • detect only one antigen
  • can distinguish between different strains of pathogens
  • can be labelled
  • can detect location of cancer cells
  • faster diagnosis
37
Q

What is the advantage of herd immunity in a population

A
  • interrupts transmission in a population

- so that those who are susceptible never encounter the infectious agents concerned

38
Q

What is the virus that causes the common cold

A

rhinovirus

39
Q

Diseases caused by protoctists

A

malaria

sleeping sickness

40
Q

Effects of leukaemia

A
  • anaemia and risk of excessive bleeding

- more susceptible to infection/immunosuppressed

AS Level Biology (10 decks)

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