Blood and Immunity

The average person has about 5L blood

-45% = blood cells-55% = fluid (plasma)

These parts can be separated by centrifuging

Components of the Blood

1) Plasma 90% of plasma is water, but also

contains blood proteins, glucose, vitamins, minerals, dissolved gases and waste products of digestion

plasma proteins help maintain homeostasis:-albumins : osmotic balance

-globulins : produce antibodies for protection against invading microbes

-fibrinogens: blood clotting

2) Erythrocytes: red blood cells

transports oxygen in hemoglobin

hemoglobin is an iron containing pigment

Anemia

Lack of iron in diet, or lack of processing of iron into hemoglobin

Can be treated with iron supplements

Each Hb molecule can carry four oxygen molecules – oxyhemoglobin or Hb(O2)4

RBCs have a biconcave shape = concave on both sides-increases surface area for gas exchange

RBCs have no nucleus = enucleated-enables the cell to carry more hemoglobin

Reproducing Red Blood Cells

bone marrow is the site of RBC reproduction = erythopoiesis

5 million RBCs are produced every minute of the day

RBC's begin as stem cells and contain a nucleus : divide – shrink- nucleus disappears – discharge into blood

immature RBC's can undergo mitosis (have nucleus)

mature RBC's cannot undergo mitosis (no nucleus)

males = 5.5 million RBCs per milliliter of blood

females = 4.5 million/mL

Increased altitudes may effect number of red blood cells.

How?there is less oxygen available

so the body compensates by creating more RBCs

a hormone called erythropoietin is produced by the kidneys and stimulates red blood cell production.

Blood Doping

Storing your own red blood cells for donation before sporting events

Increases oxygen carrying capacity

Also can use EPO (erythropoietin) as an injection

Difficult to catch

3) Leukocytes: white blood cells less numerous than RBCs have a nucleus some are phagocytes: engulf foreign

cells, release an enzyme that digests the invader

-remaining fragments are pus

some are lymphocytes-produce antibodies

4) Platelets initiate clotting

maintains homeostasis by preventing the loss of blood from torn or ruptured blood vessel

platelets break apart and release a protein called thromboplastin

thromboplastin + calcium ions activate prothrombin which is then converted into thrombin

thrombin then acts as an enzyme by splicing two AA's from a fibrinogen molecule

fibrinogen is converted into fibrin threads which seal the cut

Blood GroupsKarl Landsteiner -->different blood

types exist

glycoproteins are makers located on the membrane of some of the RBC's (A,B, or nothing) = antigen

The body produces antibodies for foreign antigens

Blood Type

Antigen Antibody

A A Anti-BB B Anti AAB A & B noneO none Anti-B &

Anti A

antibodies attach to antigens and cause the blood to clump or agglutinate

agglutinated blood can no longer pass through the capillaries and clogs the tissues preventing oxygen and nutrient delivery

blood type AB is the universal acceptor (can accept all blood types)

blood type O is the universal donor (can be given to anyone but can only accept O)

Rhesus Factor

the rhesus factor is another antigen on the RBC

if you have the rhesus factor you are said to be Rh+ (85% of Canadians)

no antigen = Rh

Rh- can donate blood to Rh+, but not reverse

there are no natural antibodies against the Rh factor, are produced after a transfusion

Erythroblastosis fetalis

Concern when mom is Rh- and baby is Rh+

first pregnancy there is no problem

During birth, the blood of the child and mom mixes

now mom makes antibodies against Rh+

second pregnancy : if embryo is Rh+, the antibodies may diffuse across the placenta and destroy the embryo’s red blood cells

Treatments:

1. transfusions of Rh- blood

2. injections to inhibit the formation of antibodies against Rh+ antigens

Immune Response

The body's first line of defense is physical: skin, mucus, stomach acids, lysozymes

The second line of defense is utilized when invaders (antigens) take up residence within the body

leukocytes seek out and destroy the invader by phagocytosis

lymphocytes produce antibodies

Two Types of Lymphocytes

1. T cells

produced in the bone marrow, stored in the thymus gland

seeks out the intruder and signals the attack

2. B cells:

produce the chemical weapon: antibodies

released from bone marrow

Antibodies are "Y" shaped

they are specific and connect to a certain antigen “lock and key”

Antibodies that attach themselves to viruses alter their shape and prevent access to the entry ports of cells

Steps to an immune attack

1. Bacteria or virus –the antigen- enters the body

2. A macrophage engulfs the invader and pushes its antigen markers outside of the membrane

3. Helper T cells recognize the harmful markers and signal the B cells

4. B cells release antibodies which attach to the antigen

5. Killer T cells now recognize the foreign cell and kill it

6. The battle has been won so Suppressor T cells shut down the response

7. Memory T cells are made so the body can quickly identify the antigen should it return (immunity)

Immunity website

Allergies: body mistakes harmless cells for harmful invaders

Autoimmune disease: body attacks itself, ex rheumatoid arthritis

Vaccines

First vaccine developed by Edward Jenner in 1796

reasoned that exposure to less harmful cowpox virus provided some immunity to the more violent smallpox virus

the first exposure to cowpox developed antibodies and because the two viruses are so similar, when smallpox was introduced T cells signalled B cells to produce antibodies

the rabies vaccine was developed by Louis Pasteur

he was able to grow the rabies virus in tissue cultures and inject the virus in milder form

Jonas Salk introduced the Polio vaccine in 1955

Summary: How do vaccines work?

a weakened microbe is injected into a person. The immune systems creates antibodies against that disease

Antibioticsantibiotics are special chemical

agents usually obtained from living organisms

in 1924 soil organisms were identified as the producers of a bacteria killing substance called actinomycetin

1929 it was found that mold produced bacteria destroying secretion = penicillin

Summary: How do antibiotics work?

they kill bacteria in your body but do not create immunity

Unfortunately, micro-organisms have the ability to mutate and become immune to antibiotics, so they can become less effective if overused.

White Blood Cell Review Used when antigens (bacteria/virus)

get inside our first line of defense– First line of defense is our skin, mucus,

stomach acids and lysozymes (enzymes that attack bacteria)

3 Types of White Blood Cells (Leukocytes)– First Type – Phagocytes (Macrophage):

engulf foreign cells, release an enzyme that digests the invader. remaining fragments are pus

– Or a Macrophage (Phagocyte) engulfs the invader and pushes its antigen markers outside of the membrane

White Blood Cell Review Second Type (Lymphocytes) – T Cells: there are many different types of T Cells.– Helper T Cells: recognize harmful

markers (from the work of the macrophage) and signal the B Cells

– Killer T Cells: now recognize the foreign cell and kill it

– Suppressor T cells shut down the response once the battle has been won

– Memory T cells are made so the body can quickly identify the antigen should it return (immunity)

White Blood Cell Review In between the Helper T Cells and

the Killer T Cells work, B cells (also Lymphocytes) release antibodies which attach to the antigenB Cells:-produce the chemical weapon: antibodies

-released from bone marrow

-Antibodies are "Y" shaped

There are 2 types of leukocytes:

1. Granulocytes – formed in the bone marrow, have granules in the cytoplasm

– Neutrophils – 60-70% - phagocytes– Eosinophils – 2-4% - engulf antigen-

antibody complexes– Basophils – release histamines, that

cause capillaries to dilate 2. Agranulocytes – formed in the

lymph tissue, have no granules in the cytoplasm

– Lymphocytes – 25-30% make antibodies in lymph and blood

– Monocytes – phagocytes, engulf foreign cells

Leukocytes