The Blood - Chp 25

Blood

a tissue make up of cells suspended in fluid that is transported by the circulatory system

What are the 4 things blood is composed of?

• plasma 55%
• red blood cells 44%
• white blood cells <1%
• platelets <1%

Plasma

the liquid part of the blood, pale golden colour

What is plasma made up of?

• 90% water
• 7% proteins
• 3% dissoved materials

What are the main 2 proteins found in the plasma?

antibodies- produced by the white blood cells to fight foreign bodies
clotting proteins - used to form blood clots

What is the function of plasma?

• transports dissolved materials, eg glucose, hormones, urea, CO2, amino acids, minerals, vitamins + salts
• transports heat

Serum

plasma from which the clotting proteins have been removed, but contains the other plasma-soluble materials, used in injections

What is the other name for red blood cells?

erythrocytes

Where are red blood cells made?

bone marrow

What makes red blood cells different from other human cells?

• no nucleus (when first made they contain nucleus but lose it within a few days)
• no mitochondria

How are red blood cells recycled by the body?

• cannot repair themselves (no nucleus) so only live for approx 120 days
• dead rbc broken down in the liver and spleen
• iron from the haemoglobin is stored in the liver and can be recycled to make new haemoglobin in the bone marrow
• the rest of the rbc and haemoglobin is converted to bile pigments (biliverdin + bilirubin)

What are the 2 bile pigments made from the waste of red blood cells?

biliverdin + bilirubin

What is another name for mature red blood cells?

red blood corpuscles

What shape are red blood cells + what is the advantage of this shape?

biconcave shape for larger surface over which they can exchange oxygen

What is the function of a red blood cell?

to transport oxygen around the body

How do red blood cells carry out their function?

• red blood cells contain haemoglobin which is a red pigment protein
• haemoglobin is based on molecules of iron and can form a loose chemical bond with oxygen to form oxyhaemoglobin (red)
• oxyhaeomoglobin loses oxygen to the body's cells and reverts to haemoglobin (purple)

What condition affects red blood cells + what are the symptoms and causes?

• anaemia is a deficiency in which the body lacks a sufficient amount of iron, therefore causing a lack of haemoglobin in the red blood cells
• symptoms include fatigue, dizziness and fainting
• causes include a diet low in iron, heavy menstruation

What is the other name for white blood cells?

leucocytes

Where are white blood cells made?

bone marrow

Describe the structure of a white blood cell:

• larger and less numerous than red blood cells
• have no definite shape
• have a nucleus

What is the function of white blood cells?

to defend the body against infection and to fight infections already in the body

What are 2 types of white blood cells?

lymphocytes and phagocytes

Describe the structure of a lymphocyte:

• large, round nucleus
• very little cytoplasm

What percentage of wbc are lymphocytes

25%

Where do lymphocytes mature?

in the lymphatic system (spleen, lymph nodes, tonsils)

What is the function of a lymphocyte?

• produce antibodies to fight off foreign substances such as bacteria and viruses

What percentage of wbc are phagocytes?

5%

What are the other names for phagocytes?

• monocytes
• macrophages

What is the function of a phagocyte?

• they engulf bacteria and foreign substances that enter the body and digest them
• the way in which a wbc engulfs these particles is called phagocytosis

Describe the structure of a phagocyte:

• kidney shaped nuclei

What is an example of a condition that affects white blood cells + what are the symptoms and causes?

• leukaemia is a form of cancer in which wbc are produced too rapidly, causing them to be immature and abnormal
• increased production of abnormal wbc overcrowd the other blood cells, suppressing the production of normal blood cells
• symptoms include fatigue, prone to bruising, enexplained weight loss

What is the other name for platelets?

thrombocytes

Where + how are platelets made?

• made in the bone marrow
• from large cells called megacytes, they are broken down to produce cell fragments called platelets

How big are platelets proportional to other blood components?

smaller than red blood cells

What is the function of platelets?

to clot the blood

What causes a clot + what is the function of the clot?

• a clot results when damaged body cells produce chemicals that stimulate platelets to form a clot
• reduce the loss of blood, prevent entry of microorganisms

What is a haemophiliac?

• someone who is unable to produce one ore more of the clotting chemiclas required
• they are unable to form blood clots and therefore may suffer from excess bleeding

What is thrombosis?

• thrombosis occurs when clots are formed in the blood vessels or walls of the heart
• blood clots do not form in healthy undamaged cells, if they form in these cells they can block the vessel and cause strokes or heart attacks

Antigen

red blood cells contain a complex carbohydrate and protein chemical on the surface of their membrane known as an antigen

What are the 4 difference blood types?

A, B, AB, O

Why is blood type important?

• it is important when people are getting blood transfusions
• the body makes antibodies to destroy cells with foreign antigens on them, therefore a person cannot receive a blood transfusion unless the blood types are matched

What is the rhesus factor?

• another blood grouping system
• can either be rhesus positive Rh+ or rhesus negative Rh-
• people that are Rh+ have a rhesus factor chemical on the surface of their rbc