Blood IA %%+(+ Flashcards
List the functions of blood
- Carriage of physiologically active compounds
- Clotting
- Defence
- Carriage of gas
- Thermoregulation
- Maintenance of ECF pH
What is the average circulating volume in a typical adult male
Average 70kg
5 litres of blood:
–1L in lungs
–3L in systemic venous circulation
–1L in heart and arterial circulation
Name the plasma proteins and describe their functions
1) Albumin: create and maintain oncotic pressure; transport insoluble molecules
2) Globulin - Subdivided into a, ß, g globulins: participate in immune system
3) Fibrinogen and other clotting factors:Blood coagulation
Oncotic pressure
- Oncotic pressure, or colloid osmotic pressure, is a form of osmotic pressure exerted by proteins, notably albumin, in a blood vessel’s plasma (blood/liquid) that usually tends to pull water into the circulatory system, especially capillaries
normal lifespan of red blood cell, white blood cells and platelets in the circulation
- RBC -120 Days
- WBC- 10-13 Days
- Platelets -10 Days
Function and structure of the red blood cell
Transport O2 from lungs to tissues
Structure:
- Highly flexible
- biconcave
- non-nucleated
- diameter 7-8mm
Describe the function of erythropoietin.
Where it is synthesised?
Factors which may increase secretion?
- Erythropoiesis: process of RBC production
- Erythropoietin (EPO) is a glycoprotein cytokine secreted by the kidney in response to cellular hypoxia (low cellular O2); it stimulates erthropoesis in the bone marrow. Low levels of EPO (around 10 mU/ml) are constantly secreted, sufficient to compensate for normal red blood cell turnover.
5 main types of white blood cells
- Neutrophil
- Monocyte
- Basophil
- Eosinophil
- Lymphocyte
Difference between a monocyte and a macrophage
- Monocytes are the largest type of white blood cells and play an important role in the adaptive immunity process.
- Monocytes typically circulate through the blood for 1–3 days before migrating into tissues, where they become macrophages or dendritic cells.
- Macrophages are monocytes that have migrated from the bloodstream into any tissue in the body. Here they aid in phagocytosis to eliminate harmful materials such as foreign substances, cellular debris and cancer cells.
Viscosity
Definition: How thick/sticky blood is compared to water.
Plasma - x 1.8 thicker than water
Whole blood - x 3-4 thicker than water
Factors that affect flow rate:
- Temperature: - increase in temp decreases viscosity and vice versa. 1oC changes viscosity by around 2%
- flow rate: - decreased flow rate increases viscosity and vice versa
- haemotocrit (ratio of RBC to total blood vol): 50% increase in haematocrit increases viscosity approx. 100%
Platelets
- Platelets - membrane bound cell fragments . Rarely nucleated, 2-4mm diameter. Formation governed by Thrombopoietin
- Life span 10 days. (140-400x109/L)
- Adhere to damaged vessel walls and exposed connective tissue to mediate blood clotting
- DO NOT adhere to healthy intact endothelium.
Leukopoiesis
- WBC formation
- More complex than RBC formation
- Controlled by a cocktail of cytokines (proteins/peptides released from one cell type which act on another).
Cytokines
- Ctytokines are released from endothelial cells, fibroblasts and/or mature white blood cells.
- Stimulate both mitosis and maturation of leukocyte.
- Differential stimulation of leukopoiesis in response to infection:
- Bacterial ⇒ neutrophils
- Viral ⇒ lymphocytes
- The cytokine cocktail is therefore dynamic, changing it’s composition in response to infection to influence which white blood cell will be preferentially stimulated to form
- Differential White Cell Count allows you to differentiate between infection types.
Plasma protein
Plasma - 4% body weight, 95 % water.
Roles: Circulates biologically active molecules & compounds
Plasma proteins subdivided into 3 categories:
1) Albumin
2) Globulin - Subdivided into a, ß, g globulins
3) Fibrinogen and other clotting factors
Fluid movement/forces
Net movement of fluid between capillary and interstitial space is subject to two forces:
i) Capillary Hydrostatic Pressure (CHP) favours movement of fluid out of capillary (bulging out)
ii) Plasma protein concentration (high) favours movement of fluid into capillary
Neutrophil
- Neutrophils (also known as neutrocytes) are the most abundant type of white blood cells in most mammals.
- They are formed from stem cells in the bone marrow. They are short-lived and highly motile, as they can enter parts of tissue where other cells/molecules cannot.
- Neutrophils are phagocytes, capable of ingesting microorganisms or particles. For targets to be recognized, they must be coated in opsonins—a process known as antibody opsonization.
- They self destruct after one burst of activity.
Eosinophils
- They phagocytose antigen-antibody complexes.
- Produce histaminase, an enzyme that inactivates two inflammatory agents released by mast cells.
- A high eosinophil blood count may indicate an allergic reaction.
Basophils
- Basophils are the rarest type of white blood cell, making up only 1% of the white blood cells found in a blood smear.
- These cells are involved in immune responses to parasites.
- These cells also accumulate at sites of infection, and the release of prostaglandins, serotonin and histamine help to increase blood flow to the area of damage, as part of the inflammatory response.
- The degranulation - release of histamine also plays a role in allergic reactions such as hay fever.
Monocytes
- Monocytes are the third most common type of white blood cell; about 2-10% of leukocytes (WBC) are monocytes.
- Monocytes in the circulation are precursors of tissue macrophages that are actively phagocytic.
- Monocytes circulate in the blood for 1-3 days, and then migrate into body tissues, where they transform into macrophages.
- They will phagocytose dead cells and bacteria.
- Some monocytes can also transform into osteoclasts.
