Objectives:

* State the main constituents of blood

**Identify red and white blood cells in diagram and under the microscope

***Describe the role of RBC and Hb in oxygen transport

Composition of blood

Whole blood

55% plasma 45% cells

90% water10% solutes red white platelets

nutrients

salts

plasma proteins

hormones

Examining a blood smearTry to identify all of these on your blood smear slide.

phagocyte

Red blood cells (erythrocytes)• 5 000 000 per mm3

• biconcave discs – maximises surface area for gas exchange

• Red pigment Hb a special protein containing Fe fills the cytoplasm

• Carries Oxygen• Hb combines with oxygen to make

oxyhaemoglobin. Write a word equation.

• nucleus lost on maturation (more space for haemoglobin that carries oxygen)

• made in bone marrow

1. Oxygen diffuses from the alveoli into the blood . The oxygen temporarily attaches to Hb making oxyHb and flows through the lung capillaries.

2. Red blood cells carry the oxygen to the cells which need it.

3. The oxygen leaves the oxyHb and diffuses out of the blood to the cells and the Hb is free again as blood flows through the capillaries in the body tissues.

4. Red blood cells return to the lungs for more oxygen

Blood in Defence

Objectives:* Describe the function of phagocytes and lymphocytes in defending the body**State the role of lymphocytes in immunity***Describe the process of blood clotting

White blood cells

White blood cells are of two main types: Phagocytes and Lymphocytes

•look white when centrifuged. •Under microscope they are colourless as they do not have Hb •does not transport oxygen. • are not disc shaped but have nucleus. • are the soldiers of the body and help to defend the body against diseases. They do this by protecting the body from pathogen. •They are made in the bone marrow.

Experiment showed that laughter produces more WBC in the body and improve our immune system.

Phagocytosis flow chartPhagocytes – originate from bone marrow / foetal liver

They surround the pathogen, ingest them and take them to the food vacuole. They then digest them by using enzymes.

Lymphocytes

When a microbe enters the body the lymphocytes recognise them as foreign object and make proteins called antibodies.Antibodies attack the pathogens by:1.Making them stick together (agglutinate)2.Dissolving their cell membranes3.Neutralising the toxins some pathogens produceAntibodies are specific to only one type of pathogen.

Once one has had a disease lymphocytes are ready to produce appropriate antibodies should the pathogen enter again. This makes one immune to a particular disease.

When describing the function of either of them mention them by name and not refer to them as WBC

Like enzymes antibodies have many different shapes. Each type of antibody has a binding site that combines with one type of pathogen.

Platelets - Blood Clotting

Platelets help the blood to thicken which then forms a clot to stop bleeding otherwise there will be blood loss and pathogens would enter the body. This is another way of defending against diseases.Platelets are tiny fragments of cells which cause blood to clot e.g. when you cut yourself.Made in the bone marrowWhen a blood vessel is damaged platelets come in contact with the air and release substances to change the soluble protein fibrinogen in the plasma to insoluble protein fibrin. Fibrin form a meshwork of threads. Red blood cells get trapped in these threads to make clot which seals the cut. The clot hardens to make a scab. New skin grows under the scab

Lymph and Tissue Fluid

Objectives:* Describe the exchange of materials between capillaries and the tissue fluid** Describe the function of the lymphatic system

Make a table to write where the three types of body fluid, which are similar in composition, occur in the body.Plasma Tissue fluid Lymph

Plasma Tissue fluid Lymph

Blood vessels Surrounding the cells

Lymph capillaries

20/04/23

The four parts of blood1. RED BLOOD CELLS – contain haemoglobin and carry ______ around the body. They have no _______ and a large surface area.

2. PLATELETS – small bits of cells that lie around waiting for a cut to happen so that they can ____ (for a scab).

3. WHITE BLOOD CELLS – kill invading _______ by producing _________ or engulfing (“eating”) the microbe.

These three are all carried around by the PLASMA (a straw-coloured liquid). Plasma transports CO2 and ______ as well as taking away waste products to the ______.

Words – antibodies, clot, kidneys, oxygen, nucleus, glucose, microbes.