Unit 7 Flashcards
what are the following characteristics of blood:
Colour
pH
Volume in human body
Colour:
Oxygen rich = Bright scarlet red
Oxygen poor = Dark red
pH: 7.35-7.45
Volume:
Men: 5 - 6 litres of which approx. 47% is cells
Women: 4 - 5 litres of which approx. 42% is cells
What is the structure of blood (two compartments)
Cellular: More correctly called “formed elements” (erythrocytes/RBC, leukocytes/WBC, platelets)
Intercellular fluid: A liquid called PLASMA.
What are the characteristics of plasma?
colour
percentage of blood volume
composition
- clear, straw-coloured liquid
- about 55% of the total blood volume
- least dense component of blood
- 90% water
- contains many other essential components dissolved in the water:
Plasma proteins: 8%
Other solutes: 2%
what are the 3 categories of plasma proteins?
- Albumins
- Globulins – α , β and γ
- Fibrinogen
All plasma proteins are manufactured by the Liver, EXCEPT the γ- Globulins (also called immunoglobulins)
What is the role of albumins?
- Most abundant plasma protein (60%)
- Exerts osmotic pressure to maintain water balance between blood and tissues
- Acts as a carrier to shuttle molecules through circulation
- Blood buffer
What is the role of globulins?
- 36% of plasma proteins (alpha, beta and gamma)
- Alpha and beta: transport proteins that bind to lipids, metal ions and fat-soluble vitamins
- Gamma: antibodies released primarily by plasma cells during immune response
role of fibrinogen
• 4% of plasma proteins (clotting proteins)
structure and function of erythrocytes (RBCs)
- the most abundant blood cells
- contains haemoglobin
Function: transport oxygen and carbon dioxide via Hb
Structure:
• anucleate
• are about 6- 7.5 µm in diameter
• formed from stem cells in the red bone marrow
• Life span: 120 days
• Biconcave disc
what are the advantages of biconcave discs?
- Surface area:volume ratio is greater than from ball shape allowing enhanced diffusion
- Flexibility: Allows the cell to move through parts of the circulatory system which are too small. The cells can fold in half and squeeze through narrow capillaries.
- Minimal tension on the membrane when volume changes occur between oxygenated and venous blood.
structure and function of platelets/thrombocytes
- Colourless cell fragments formed from large cells (megakaryocytes = 60µm).
- 1 ml of blood contains 250 million platelets.
- 2 - 4 µm in diameter.
- Normally live for 5 - 10 days.
- Important during blood clotting
Structure and function of haemoglobin
- Inorganic component = Haem = Fe2+ (oxygen binds to haem = oxyhemoglobin)
- Organic component = Globin = Protein (carbon dioxide binds to globin = carboaminohemoglobin)
- Transports oxygen and carbon dioxide
what are the 2 types of Hb and what is their affinity to oxygen?
Adult (Hb A) contains > 2 alpha (α) and 2 beta (β) > low affinity to oxygen
Foetus (Hb F) contains > 2 alpha (α) and 2 gamma (γ) > high affinity to oxygen
what is Sickle cell anaemia?
- Defect in beta chain.
- Hbs becomes sickled when deoxygenated, interaction between molecules result in shape deformity and obstruction of blood flow
what is Thalassemias?
- results from absent or defective synthesis of either the alpha or the beta chains of the haemoglobin.
- Blood cells containing these abnormal forms of Haemoglobin have a short life span as they are quickly destroyed.
- This can lead to anaemia.
PORPHYRIA.
collective term for several clinical disorders affecting the synthesis of haem
function and overview of WBCs
- Protection against infection and cancer
- Less than 1% of total blood volume
- Can move out of bloodstream unlike RBCs
- Almost all the leukocytes are formed from stem cells in the red bone marrow.
what are the 5 types of WBCs?
- Neutrophils
- Basophils
- Eosinophils
- Monocytes
- Lymphocytes
Structure and function of Neutrophils
Structure:
Multilobed nucleus
Red and blue granules
10-12mm
Function:
Phagocytise bacteria
Structure and function of Basophils
Structure:
Bilobed nucleus
purplish-black/ blue granules
10-14mm
Function:
• Release histamines and other mediators of inflammation
• Contain heparin (anticoagulant)
Structure and function of Eosinophils
Structure:
Bilobed nucleus
Red granules
10-14mm
Function:
• Contain enzymes
• Kill parasitic worms that are too large to be phagocytized
• Complex role in allergy and asthma
Structure and function of Monocytes
Structure: Largest of all single horseshoe shaped nucleus grey blue cytoplasm 14-24mm
Function:
• When monocytes leave the blood stream they differentiate into macrophages in the tissues
• Crucial in defence against viruses
Structure and function of Lymphocytes
Structure:
Spherical or indented nucleus that takes up most of cell
pale blue very little cytoplasm
5-17mm
Function:
• Mount immune response by direct cell attack of via antibodies
• Lymphocytes undergo further development and cell division in tissues outside the bone marrow
what is the role of macrophages?
- Macrophages have greater appetite and large numbers of lysosomes.
- They phagocytose infectious microorganisms.
- Some of the macrophages are freely moving in the tissues while some are fixed.
where are fixed macrophages located?
- Alveolar macrophages in lungs
- Osteoclasts in bone
- Sinus histiocytes in spleen and lymph nodes
- Kupffer cells in liver
- Microglia in Central Nervous System
what are the 3 main functions of blood?
- Transportation
- Regulation
- Protection
how is oxygen transported by blood?
- O2 transported from lungs to tissues usually by Hb in RBCs
* A small amount is carried in the plasma
How is CO2 transported by blood?
- Converted into bicarbonate within RBCs and mostly carried this way
- Carbonic anhydrase (enzyme) catalyses the conversion
- Some CO2 carried combined with Hb and some dissolved in plasma
- Carried from tissues to lungs
How are nutrients transported by blood?
- They are absorbed into the blood flowing through the capillaries which are present in the villi of the small intestine.
- Some nutrients are transported dissolved in the plasma, e.g. glucose, others are transported bound to carriers (plasma proteins).
- Albumins and Globulins are important in the transport of fatty acid and lipids in the blood.
how is heat transported by blood?
- Body heat transported from warm core to cooler extremities.
- Heat is carried by the plasma as water has a great capacity for “holding” heat.
what are the 2 ways hormones are transported by blood?
- Dissolved in the plasma (protein based?)
2. Attached to a plasma protein (lipid based?)
what are the 2 stages of haemostasis?
Stage 1. Temporary: involves the contraction of the vessel wall and the plugging of the leak with platelets.
Stage 2. Permanent: involves the production of a thrombus in the vessel at the site of injury.
what are the 3 components of the normal haemostatic mechanism?
- Reaction of the blood vessel wall (stage 1)
- Reaction of the platelets (stage 1)
- Blood coagulation (stage 2)
describe the flow of the reaction of the blood vessel wall in haemostasis?
Immediately following injury, blood vessel undergoes a temporary, reflex vasoconstriction > slowing of the blood flow > Blood escapes into the tissues and causes further compression of the vessel
describe the flow of the reaction of the platelets in haemostasis?
Adhesion > swelling > develop spikes > become stickier > rupture > release substances
describe the flow of blood coagulation in haemostasis?
Coagulation factors bring about coagulation of the blood > The temporary platelet plug is reinforced by a meshwork of fibrin fibres > The meshwork traps RBCs and platelets and as a result, a fibrin clot forms > It forms a rigid and strong barrier against further blood loss > fibrin mass completely replaces the platelet plug
What are the two factors in coagulation and what is the resulting product?
- Extrinsic/tissue system (factor required for clotting is present outside the blood, in the tissue)
- Intrinsic/blood system (factors required for clotting is present within the blood)
Activity of either of these systems results in the production of PROTHROMBINASE.
what does prothrombinase create when combined with calcium ions and factor X?
Prothrombinase, in the presence of calcium ions and factor X > catalyses the reaction which converts prothrombin (inactive from of thrombin) > thrombin.
Thrombin, in the presence of calcium ions > catalyses the conversion of fibrinogen to fibrin.
why is the intrinsic pathway a slower process?
Factor XII must activate several other factors which in turn, activate factor X
why is the extrinsic pathway a faster process?
Fewer steps involved in activating factor X.
what is a clot retraction and what is its function?
Once a clot forms, it begins to contract > brings the edges of the injured tissue closer together > clot retraction
• Improves haemostasis and facilitates repair
Why is vitamin K important?
• Vitamin K is required for the synthesis of four of the clotting factors (II, VII, IX and X)
Why is vitamin D important?
• Vitamin D is required for absorption of Ca2+ (Clotting factor IV) from GI tract.
what are the two groups of leukocytes?
Specific (adaptive/acquired) immune responses:
- Involves lymphocytes
Non-Specific (innate/inborn) immune responses:
- Involves neutrophils, eosinophils, basophils, monocytes differentiating into macrophages
what can cause an inflammatory response? (4)
- physical trauma
- intense heat
- irritating chemicals or
- infection from microbes (viruses, bacteria or fungi)
what is the goal of inflammatory response?
Facilitate repair by clearing the microbes, dead tissues and cell debris from the injured site
What are the 5 inflammation characteristics?
- Redness (Rubor)
- Heat (Calor)
- Pain (Dolor)
- Swelling (Tumor)
Fifth symptom- loss of function (may occur)
what are the 2 stages of the inflammatory response?
- Vasodilation and increased permeability of blood vessel
2. Phagocytic migration
describe vasodilation and increased permeability during the inflammatory response
Increase in diameter of blood vessels > increased blood flow to the inflamed site
Increased permeability of the blood vessels > permits defensive materials (like immune cells) and plasma in the blood to reach the injured/damaged area
What are the 4 stages of Phagocytic migration?
- Leukocytosis – increase in WBC numbers
- Margination
- Diapedesis
- Chemotaxis
describe Leukocytosis
Leukocytosis occurs (increase in leukocyte numbers, especially neutrophils) > Neutrophils enter blood from the red bone marrow > Within a few hours, the number of neutrophils in the blood increases 4 – 5 times.
Describe margination
Neutrophils line-up and stick to the inner walls (margins) of the blood vessels
describe diapedesis
- emigration/ extravasation
- Neutrophils squeeze out through the narrow spaces between the endothelial cells of blood vessels, to the site of injury.
describe chemotaxis
- Inflammatory chemicals (chemotactic agents) attract the neutrophils to the site of injury
- The collected neutrophils engulf the foreign materials.
sum up the flow of events following tissue damage
Tissue injury > Vasodilation > Leukocytosis > Margination > Diapedesis > Chemotaxis > Phagocytosis > Healing
Benefits of inflammatory response (4)
- Prevents the spreading of damage causing agents
- Eliminates cell debris and pathogens from the inflammatory site
- Wakes up the adaptive/specific immune system
- Initiates repair/ healing
what are the 2 types of specific immune response?
- Humoral (blood borne) immunity by B-lymphocytes
2. Cell mediated immunity by T-lymphocytes
what is an antigen?
• foreign substance which evokes a response (inc. proteins, bacteria, viruses, and aberrant cells)
what is an antibody?
• proteins (immunoglobulins) which are produced by plasma cells in response to the presence of a foreign substance (antigen).
explain the production of lymphocytes
- Both B and T- Lymphocytes originate from stem cells in red bone marrow
- They mature at different sites: B-cells in Red bone marrow, T-cells in Thymus
what is the seeding of peripheral lymphoid organs
Mature and immunocompetent lymphocytes programmed to perform their functions are supplied to PERIPHERAL (SECONDARY) LYMPHOID ORGANS by the blood where they reside and colonize.
what are the peripheral lymphoid organs?
- Lymph nodes
- Spleen
- Adenoids
- Tonsils
- Appendix
- Peyer’s patches (lining the small intestinal tract)
what are the primary lymphoid organs?
• Red bone marrow and thymus
what is the origin of T and B cells?
- Stem cells in red bone marrow give rise to undifferentiated lymphocytes
- Undifferentiated lymphocytes enter blood
- Some lymphocytes are processed in the thymus gland to become T-cells
- Other lymphocytes are processed, probably in bone marrow, to become B cells
- T cells and B cells are transported to lymphatic organs by blood
explain the role of T-cells
- Some lymphocytes move into circulation and are carried to the thymus gland where they learn to kill micro-organisms in a certain way
- Educated T-cells re-enter circulation and move to organs where they take up residence (seeding)
- Multiply and can re-enter circulation to attack micro-organisms as educated cells
- Involved in cellular immunity (virus infected cells, cancer etc)
what are the 3 types of T-cells?
- Helper T cells
- Cytotoxic T-cells
- Regulatory T-cells
what is the role of Helper T cells?
first to be activated when antigen is present. They secrete substances that stimulate the activity of other defence cells
what is the role of Cytotoxic T-cells?
directly attack anormal cells of the body
what is the role of regulatory T-cells?
last group to be activated. Inhibit immune response and prevent it getting out of control and help control autoimmune diseases
explain the role of B-cells
- Some lymphocytes remain in bone and learn how to attack micro-organisms by producing antibodies
- Leave bone and enter circulation and seed the same tissues as the T-cells
- Involved in humoral immunity (extracellular: bacteria, fungi, parasites etc)
- Effector cells = plasma cells
what are the 5 stages of lymphocyte development?
- Origin
- Maturation
- Seeding secondary lymphoid organs and circulation
- Antigen encounter and activation
- Proliferation and differentiation
what is the difference between active and passive immunity?
Active immunity takes place when the host produces antibodies when exposed to pathogens or bacteria while passive immunity takes place when the host receives antibodies from another source
where is red bone marrow found in adults
- flat bones (bones of axial skeleton and girdles)
- proximal epiphyses of the humerus and femur.
why can RBCs not reproduce and what is the process of their breakdown?
- Lack of nuclei and organelles means they cannot repair or reproduce
- After about 120 days, cells wear out
- Dying cells are phagocytosed by macrophages
- Occurs in spleen, liver and bone marrow
- Iron (haem) released into plasma and binds to transferrin > delivered back to bone marrow and reused to make new RBCs
- Remaining porphyrin ring is converted to bilirubin
what happens to the bilirubin created from RBC breakdown?
- Bound to plasma albumin and transported to liver and excreted as part of bile
- Green/yellow bilirubin converted into brown stercobilin by bacteria in large intestine
- Globin part of Hb is degraded in AAs and recycled
