Blood Composition

Blood is a collection of different cells that moves around the body. Blood is made up of: Plasma Red Blood Cells White Blood cells Platelets

Function of Blood Bloods main functions are: 1.Transport nutrients to the body cells. 2.Remove waste from the body cells. 3.Regulates the body temperature. 4.Defence of the body.

Red Blood Cells Highly specialised cell design for carrying oxygen around the body and to squeeze through tight structures. Made in the bone marrow and has a life span of 100 days. They are destroyed in the spleen

Spleen

Red Blood cell Structure Have a large membranes to protect the cell as it squeezes through the capillary. Contains no nucleus so it can fit in a large protein structure call a haemoglobin. No mitochondria, so not to use up the oxygen.

Haemoglobin An iron containing protein that combines with oxygen readily to form oxyhaemoglobin. They have a biconcave shape and a high surface area to volume ratio to make the exchange with oxygen efficient. Thin surface membrane to assist diffusion.

Picture Haemoglobin

White Blood cells are also known as Leucocytes as they are colorless due to lack of Haemoglobin. There are about of WBC for 1ml of blood. These are also called Scavengers & Microscopic policemen White Blood Corpuscles/cell

White Blood Cells Five Types of white blood cells White blood cells function/ defend the body by either: 1. Phagocytosis 2. Antibody production

Type of WBC’s Granulocytes—have large granules in their cytoplasm Neutrophils Eosinophils Basophils

Types of WBC’s Agranulocytes—do not have granules in their cytoplasm Lymphocytes Monocytes

Phagocytes Several lobes in nucleus 70% of WBC count Highly mobile/very active Phagocytosis, contain several lysosomes (digestive enzymes) They produce a pseudopodia that will surround the bacteria or foreign material.

Lymphocytes Smallest WBC Large nuclei/small amount of cytoplasm Account for 25% of WBC count Make chemicals called antibodies which are soluble proteins. Two types—T lymphocytes—attack an infect or cancerous cell, B lymphocytes—produce antibodies against specific antigens (foreign body)

Antibody Action Antibodies attached to the antigens, which are chemical markers on the membranes of pathogens. Antigens are protein structures (lock and key concept)

How are Antibodies effective  Antibodies destroy a pathogen by:  Causing bacteria to stick together so it can be engulfed by phagocytes  Mark out or label the pathogen for the phagocytes.  Cause bacterial cells to rupture  Neutralise poisons produced by the pathogens.

Formation of WBC’s Leucocytes are formed in the red marrow of many bones. They can also be formed in lymphatic tissue. They live for about days.

Memory Cells o Some lymphocytes develop into memory cells. o Memory cells make is what gives us immunity. o After infection, immune response shutdown and most of the participating cells die, except for the memory cells.

The B and T Cells  The Lymphocytes can be classed as B cells and T cells.  B cells are produced and develop in the bone marrow  T cells are produced in the bone marrow but develop in the thymus gland (Lymph node: exposes lymphocytes to filtered pathogens)

Picture of Memory Cells and Secondary Immune Response

Primary Immune Response ΩThis is the name given to the response system when the body is first infected. ΩThis is the development of antibodies by the lymphocytes. ΩLymphocytes first must develop the antibodies that will attach to the antigens. ΩThis means the number of antibodies produced are smaller and this takes longer to occur.

Secondary Immune Response Faster and more effective then the primary immune response. When the same pathogen invades the body, many antibodies will be produced over a short period of time, meaning that the pathogen will be destroyed quickly (the symptoms of the pathogen way not even be expressed by the body).

Picture of graph showing secondary response

Vaccination  Giving the body artificial immunity.  Person is injected with an agent that carries the same antigens of a specific disease causing pathogen.  The agents are harmless (usually a dead pathogen) but it allows the lympocytes to form memory cells for an effective secondary immune response.

Types of vaccines Agents used as vaccines include: 1.Weaken strain of the actual pathogen 2.Dead microorganisms 3.Modified toxins of bacteria 4.The antigen itself 5.Genetically modified harmless bacteria.

Bone Marrow Bone marrow produces red blood cells, white blood cells and platelets. There are two types of bone marrow: Red Yellow (fatty tissue deposits)

Platelets o Fragments of a larger cell made in the bone marrow. o When cut, air stimulates a chemical release from the damage tissue and platelets o The chemical causes a soluble plasma protein called fibrinogen to become an insoluble protein called fibrin. o This protein fibre forms a sticky network that traps cells to become a clot.

Clotting Once the clot is formed, a scab will appear, which will then allow new tissue to form underneath. The aim of the clot is to block any further invasion of pathogens from the outside environment. Make a flowchart in your notes to show how the blood clotting occurs.