Immunity and lymphatic system

What is blood?

• A (liquid) connective tissue composed of cells and a fluid extracellular matric

• It performs transport, regulatory and protective functions

Label the components inside the blood

What are the percentages of the compotents of blood?

Describe haemopoiesis

What is leukaemia

common myeloid progenitor

(a multipotent stem cell in the bone marrow that differentiates into non-lymphoid blood cells, including red blood cells, platelets, and most white blood cells)

What is lymphoma

- natural killer cell (large granular lymphocyte)

What cells count as myelomas?

• T lymphocytes

• B lymphocytes

• Plasma cells

Label the diagram of hemocytobasts/ blood cancers

Describe A blood group

• A antigens on its surface

• anti-B antibodie in the blood

Describe B blood group

• B antigens on its surface

• anti-A antibodies in the blood

Describe AB blood group

• Has both A and B antigens on its surface

• No antibody on the surface

  • Rarest blood group

Describe O blood group

• No red blood cell antigens on its surface

• Anti-A and anti-B antibodies in the blood

  • most common

What are the granular types of leucocytes

• Neautrophil= first responders, phagocytosis and release toxins

• Eosinophil= manages allergic reactions and parasitic infections, releases cytotoxins, proteins and lysozymes

• Basophil= releases histamine, heparin and serotonin during inflammation and allergic reactions. closely related to mast cells

What are the agranular types of leucocytes

• Monocyte= macrophage, fixed and wandering. Transform into phagocytes when active.

• Lymphocytes= T cell, B cell and Natural Killer cell which control adaptive immune response. develop in primary lymph organs (red bone marrow and thymus) and undertake functions in secondary lymph organs (spleen, lymph nodes, tonsils, appendix and other lymphoid tissues)  

Describe the lymphatic system

• It drains excess interstitial fluid, transports dietary lipids/ fat-soluble vitamins, and facilitates immune responses

 • Lymph vessels have permeable walls and valves.

• Lymph drains into the thoracic duct and right lymphatic duct before returning to the blood circulation.

Label the lympathic system on the body

•Lymphatic system drains excess interstitial fluid, transports dietary lipids/ fat-soluble vitamins, and facilitates immune responses

•Lymph vessels have permeable walls and valves.

•Lymph drains into the thoracic duct and right lymphatic duct before returning to the blood circulation. Relies on skeletal muscle and respiratory pumps.

Where does the lymph drain out to?

Thoracic duct

Label the structure of the kidney and it’s lymph vessels

Describe the spleen

•Rich blood supply and filters blood through white and red pulp.

•White pulp of T and B lymphocytes and macrophages perform immune clearance of pathogens.

•Red pulp maintains red blood cell health.

  - macrophages remove old erythrocytes

  - stores iron

  - stores platelets

What happens if the spleen goes under trama?

•Trauma can result in haemorrhage and splenectomy, which can reduce immune function (may require prophylactic antibiotics).

What are the two types of immune defences?

• Innate defences

• Adaptive immunity

Describe innate defences

• 1st line= Physical barriers created by skin and mucus membranes

• 2nd line= antimicrobials, natural killer cells, phagocytes, fever, inflammation.

Describe adaptive immunity

• T lymphocytes= cell-mediated response by cytotoxic/ memory T cells, helper T cells, and suppressor T cells.

• B lymphocytes= antibody-mediated response by Plasma and Memory B cells.

Describe the 1st line of innate adaptation around the body

• Eyes= tears from glands in the eyelids wash away dirt + have antiseptic substance

• Mouth= glands produce saliva, a mixture of mucus and enzymes that cleans the mouth

• Respiratory tract= mucus traps pathogens and cilia sweep mucus to the throat

• Stomach= hydrochloric acid, kills most organisms

• Intestines= goblet cells produce mucus, which protects the lining from digestive chemicals and harmful organisms.

• Genital and urinary tract= “Harmless” bacteria within the genital tract and the flushing action of urine in the urinary tract both help prevent the growth of harmful organisms.

• Skin= protected by sebum , and sweat. Both of these are mildly antiseptic. Hair provides a protective coat.

Describe the 4 elements of the 2nd line of the innate immune system

• Anticrobials= interferons, iron-binding proteins & complement.

• Natural killer cells= immunological surveillance, direct attack upon a range of microbes, infected and cancerous cells

• Phagocytes= phagocytosis of pathogens. Secrete wastes and display fragments for antigen recognition.

• Fever= pyrogens increase temperature set-point. Increase metabolism, immune function and makes inhospitable environment for pathogens.

Describe inflammation as a 2nd line innate immune system step

Inflammation is a protective response but causes local tissue swelling, erythema, heat and pain. 

1. Vasodilation and capillary permeability.

    Mast cells release histamine and heparin.

2. Migration of phagocytes.

     Neutrophils engulf pathogens and secrete cytokines    which attract monocytes (transform into macrophages) by chemotaxis. Fibrin network prevent spread of microbes.  

3. Tissue regeneration.

    Healing and fibroblasts secrete collagen to form a scar.

• C-Reactive Protein (CRP) is a non-specific biochemical maker of inflammation.

• Inflammatory process stimulates the adaptive immune system.

Describe T lymphocytes (cell-mediated) role in the adaptive immune system

Three types of T cell:

1.- Cytotoxic T cell/ Memory T cell (CD8⁺)

2.- Helper T cell (CD4⁺)

3.- Suppressor T cell

• T cells detect antigens presented by MHCs at the cell surface.

• Activated by antigen recognition and co-stimulation by Helper T cells.

• T cells undergo clonal selection to produce Cytotoxic T cells and Memory T cells.

• Cytotoxic T cells attack pathogens using perforin, granzymes, lymphotoxin and stimulating apoptosis.

• Memory cells enable a much quicker secondary response on exposures to the same antigen, while Suppressor T cells stop the response to protect healthy tissues from damage.

Describe T lymphocytes (cell-mediated) role in the adaptive immune system picture

Describe B lymphocytes (antibody/humoral) role in the adaptive immune system picture

•B cells do a chemical attack on pathogens using antibodies

•They are activated by specific antigen and co-stimulation of T Helper cells

•Undergo clonal selection to produce active plasma cells and memory cells.

•Plasma cells secrete antibodies or immunoglobulins (IgG, IgE, IgD, IgM, IgA).

What are the functions of antibodies

1.  Neutralise pathogens

2.  Agglutination (clumping of pathogens)

3.  Activates the complement system

4.  Attracts phagocytes

5.  Opsonisation (allow phagocytes to attach)

6.  Stimulates inflammation

7.  Prevents pathogen adhesion to skin and mucus      membranes

Describe immunological memory

•Development of memory T and B cells during a primary immune response allow a much faster and more powerful secondary immune response on exposure to the same antigen.

•This avoids disease by  creating naturally-acquired active immunity.

•Vaccines use this principle, and provide artificially-acquired active immunity.

•Passive immunity through the transfer of antibodies can be naturally- (placenta/ breastfeeding) or passively- (clinical therapy) acquired.   

What does non-pathogenic mean

They dont cause disease and can be beneficial

Label bacterial structure

What are multi-resistant infectios

• Happens when micro-organisms change when they are exposed to antimicrobial drugs. Micro-organisms that develop this are referred to as ‘superbugs’.

•The ability to prevent and treat a range of infections is threatened.

•Antimicrobial resistance can occur naturally over time but its known that the overuse or misuse of antibiotics can accelerate the process.

Describe viral structure and replication

What is immunosuppression

a reduction in the efficiency of the body’s immune system, resulting in a weakened ability to fight infections and diseases.

Describe how a local inflammation is dealt with

• Pathogenic antigens/ cell damage detected

• Mast cells release histamine and heparin, causing vasodilation and increased vessel permeability

• Clotting factors and complement proteins migrate into interstitial space. Phagocytosis and release of cytokines. Fibrin network forms to trap microbes.  

• Monocytes attracted to the area – transform into phagocytic macrophages and release proinflammatory cytokines (e.g. IL-1, IL-6 and TNF). Recruitment of lymphocytes

• Fibroblasts secrete collagen to form a supportive scar as tissue heals and remodels.

Describe sepsis

• “Sepsis is a dysregulated response to infection”    

• Improvement in outcomes relies on early identification and treatment.

• Complex syndrome of pathophysiological pathways which can present with a range of non-specific symptoms, making diagnosis challenging.

• Usually happens of patients that are already sick

What are the risk factors of sepsis

Pathophysiology of sepsis

•Sustained inflammatory signals/ bacterial challenge can lead to systemic (rather than localised) inflammation

•Activated white blood cells and build up of cytokines damage blood vessel endothelium.

•Damaged endothelium releases nitric oxide (NO) which causes further vasodilation and permeability, as well as more cytokines, complement and activated clotting.

•Procoagulant states (called disseminated intravascular coagulation - DIC) can result in microemboli and further tissue ischemia.

What is a septic shock

• sepsis causes dangerously low blood pressure and cellular abnormalities

• Hypotension results in hypoperfusion of tissues and build-up of wastes.

• Cells are starved of oxygen/ glucose and resort to anaerobic respiration, generating lactate. Results in lactic (metabolic) acidosis.

• Cell function is affected and intracellular salts accumulate. Fluid shifts from intravascular to interstitial and then intercellular space

• Damaged cells leak enzymes which injuries other neighbouring cells.

•Viscous cycle of cell dysfunction leads to multi-organ failure. 

•Diagnosed when: serum lactate >2mmol/L and vasopressors are required to maintain mean arterial pressure (MAP) ≥65mmHg.

What do you have to do when Sepsis happens