Biochem Enzymes MNEMONIC

Who wants a box of chocolates when you can have a petri dish of bacteria?

Haematology

White Blood Cells (Leukocytes)

Neutrophils, eosinophils and basophils = granulocytes (polymorphonuclear leukocytes)

Monocytes & lymphocyes = mononuclear

Neutrophils

Most numerous (~60% of WBC)

Nucleus divided into lobes

Cytoplasm contains small granules

Stains pink with Romanowsky dyes

Lifespan of 6-10hrs

Exit into tissues - non-specific defence against bacteria and fungi

Eosinophils

1% of circulating leukocytes 

Large cytoplasmic granules - stain strongly with acidic dye eosin

Nucleus is bilobed

Circulate for 4-5hrs

Exit to tissues –> 

Defence against parasites 

Dampen allergic response

Tissue eosinophils are also capable of responding to bacterial and fungal infection in a similar way to neutrophils.

Basophils

Least numerous (<1%)

Large granules stain strongly with basic dye methylene blue

Involved in anaphylactic hypersensitivity and inflammatory reactions

Monocytes

5% of circulating leukocytes

Large cell

Kidney/clefted shaped nucleus

Scattering of delicate azurophilic granules

Circulate for 10hrs

Mature into phagocytic tissue macrophages

Responsible for the removal of aged RBCs and other debris

Process and present antigens to T-lymphocytes 

(Macrophages are formed in response to an infection or accumulating damaged or dead cells. Large, specialized cells that recognize, engulf and destroy target cells.)

Lymphocytes

Second most common leukocyte (33%)

Much less cytoplasm - nucleus almost fills cell

Variable lifespan

Receptors on surface recognise foreign substances

Several types of lymphocyte - click here

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It’s Medical Mnemonics Monday!

Renal Papillary Necrosis is a form of nephropathy characterized by coagulative necrosis of the renal medullary pyramids and papillae.  

Causes of Papillary Necrosis can be remembered by the mnemonic “POSTCARDS”.

P yelonephritis

O bstruction of the urogenital tract

S ickle cell disease

T uberculosis

Chronic liver disease,

A nalgesia /A lcohol abuse,

R enal transplant rejection

D iabetes mellitus

S ystemic vasculitis

Check out the list of the previous Medical Mnemonics here.

Antibodies (Human)

The ‘foot’ (bottom) of the antibody is known as the Fc fragment - binds to cells, binds to complement = effector function (kills or removes antigen)

The top (antigen binding) is the Fab fragment

Chains are held together with disulphide binds

Associated molecules allow intracellular signalling 

Normally 3X constant heavy chain domains per chain and a hinge region (except μ and ε which have 4 and no hinge region)

Classes of Immunoglobulins

The five primary classes of immunoglobulins are IgG, IgM, IgA, IgD and IgE,  distinguished by the type of heavy chain found in the molecule. 

IgG - gamma-chains

IgMs - mu-chains

IgAs - alpha-chains

IgEs - epsilon-chains

IgDs - delta-chains.

Differences in heavy chain polypeptides allow different types of immune responses. The differences are found primarily in the Fc fragment. There are only two main types of light chains: kappa (κ) and lambda (λ), and any antibody can have any combination of these 2 (variation).

IgG 

monomer

Gamma chains

70-85% of Ig in human serum. 

secondary immune response 

only class that can cross the placenta - protection of the newborn during first 6 months of life

principle antibody used in immunological research and clinical diagnostics

21 day half life

Hinge region (allows it to make Y and T shapes - increasing chance of being able to bind to more than one site)

Fc strongly binds to Fcγ receptor on phagocyte - opsono-phagocytosis

Activates complement pathway

IgM

Serum = pentamer 

Primary immune responses - first Ig to be synthesised

complement fixing 

10% of serum Ig 

also expressed on the plasma membrane of B lymphocytes as a monomer - B cell antigen receptor

H chains each contain an additional hydrophobic domain for anchoring in the membrane

Monomers are bound together by disulfide bonds and a joining (J) chain.

Each of the five monomers = two light chains (either kappa or lambda) and two mu heavy chains.

heavy chain = one variable and four constant regions (no hinge region)

can cause cell agglutination as a result of recognition of epitopes on invading microorganisms. This antibody-antigen immune complex is then destroyed by complement fixation or receptor mediated endocytosis by macrophages.

In humans there are four subclasses of IgG: IgG1, IgG2, IgG3 and IgG4. IgG1 and IgG3 activate complement.

IgD 

B cell receptor

<1% of blood serum Ig

has tail pieces that anchor it across B cell membrane

forms an antigen specific receptor on mature B cells - consequently has no known effector function (don’t kill antigens, purely a receptor) (IgM as a monomer can also do this)

IgE 

Extra rigid central domain

has the most carbohydrates

IgE primarily defends against parasitic invasion and is responsible for allergic reactions.

basophils and tissue mast cells express very high affinity Fc receptors for IgE - mast cells then release histamine

so high that almost all IgE is bound

sensitizes (activates) mucosal cells and tissues 

protects against helminth parasites

IgE’s main purpose is to protect against parasites but due to improved sanitation these are no longer a prevalent issue across most of the world. Consequently it is thought that they become over activated and over sensitive while looking for parasites and start reacting to eg pollen and causing allergies.

IgA

Exists in serum in both monomeric (IgA1) and dimeric (IgA2) forms (dimeric when 2 Fcs bind via secretory complex)

15% of the total serum Ig.

4-7 day half life

Secretory IgA2 (dimer) = primary defense against some local infections

Secreted as a dimer in mucous (e.g., saliva, tears)

prevents passage of foreign substances into the circulatory system

Isotype: class of antibody (IgD, IgM etc)

Allotype: person specific alleles 

Idiotype: (hyper) variable region - antibody specificity 

Strep throat.

Remember to use your sponge to replace any bacteria on your dishes accidentally removed by the act of eating.

Microbiology professor (via scienceprofessorquotes)

I made a lymph drainage sticker for the immuno section of first aid

You can get the Sticker here: https://www.redbubble.com/people/histrionicole/works/29980305-lymph-node-drainage?asc=u&p=sticker

MORE MIXED MNEMONICS

Horizontal gene transfer