WK 4 River OF LIFE PDF

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Week 4 - the river of life...

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HUBS 1406 WK 4 – THE RIVER OF LIFE COURSE OUTLINES List the physical characteristics and functions of blood. - Blood  a fluid connective tissue that circulates continually around the body Characteristics - Sticky, opaque fluid - Colour  scarlet to dark red - pH 7.35 – 7.45 slightly alkaline - temp  38 degrees Celsius - 8% of our body weight - average volume  females: 4-5L males: 5-6L Functions 1. Transport - Dissolved gases, oxygen (02) and carbon (CO2) - Nutrients from the GI tract to all cells - Fat from stores to cells of the body - Metabolic wastes for elimination, either via the lungs (e.g. CO2) or the kidneys (e.g. Urea) - Hormones (and drugs) from their point of origin (or administration) to their sites of action 2. -

Homeostasis Helps regulate body temperature by losing or gaining heat from the environment and distributing hea Helps to regulate pH  contains buffers Helps to regulate circulating blood volume due to the osmotic “pull” of its plasma proteins

3. Defence - Blood defends against infection  contains many components of our immune system, including white - Blood contains a host of clotting factors and also platelets to initiate clot formation and prevent exces blood vessels is broken Blood is made out of: - 55% PLASMA  consisting of water mainly (92%) with plasma proteins (7%) and other solutions (1-2% - 45% FORMED ELEMENTS  consisting of erythrocytes mainly (99.(%) but also leukocytes and platelet

List the components of plasma and describe their functions. PLASMA PROTEINS - mostly produced by the liver  stay in the blood because they are too big to escape through the sem - because the molecules are trapped in the blood vessels, water is also held in the blood vessels by osm - Has a consistency of interstitial fluid They contain: - 60% albumin  maintain normal plasma osmotic pressure, carrier molecules for free fatty aids, some - 35% globulins  antibodies (immunoglobulins), transport proteins e.g. transferrin – iron; thyroglobul - 4% clotting factors  most abundant is fibrinogen - 1% regulatory  enzymes, hormones

The other solutes - nutrients e.g. glucose, amino acids - nitrogenous waste products e.g. urea, creatine - hormones - respiratory gases  CO2 and O2 Briefly explain what the basic blood tests can show and how they are used to provide clinically relevant in blood collection for analysis Venepuncture - superficial vein at anterior surface of the elbow - performed by doctors, nurses or specially trained blood collectors called phlebotomists Capillary puncture - finger tip, ear lobe, big toe or heel Arterial puncture - radial artery at wrist, brachial artery at elbow - used to check efficiency of pulmonary gas exchange - performed by doctor for specially trained nurse Introduction to blood test

Briefly describe haematopoiesis the production of all the cellular components of blood and blood plasma  occurs within the hemato organs and tissues, e.g. bone marrow, liver, and the spleen - the stem cells give rise to all the formed elements  most of the formed elements survive in the bloo do not divide Where does it occur? - In the red bone marrow - Adults  red bone marrow is found in flat and irregular bones (vertebrae, skull, sternum, ribs, pelvis), and at the end of long bones - Bone marrow that no longer produces blood cells is called fatty yellow marrow -

Understand the roles of erythrocytes, leucocytes (the various types) and platelets. -

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red blood cells (erythrocytes)  transport the haemoglobin and oxygen throughout the body e.g. res Normal numbers in blood:  males 4.5 – 6.5 x 10^12/L  female  3.8 – 5.8 x10^12/L  biconcave discs  giving huge surface area relative to volume for gas exchange  no nucleus or other organelles  leave maximum room for haemoglobin  packed with haemoglobin for gas transport  no mitochondria  ATP production in anaerobic  flexible  can squash down when going through smaller capillaries Fate of erythrocytes  experiences several mechanical stresses  a single round trip takes about a minute  bounces off vessel walls, collides and squeezes through capillaries  in 120 days it travels over 1100km and circulates some 300,000 times  cannot make new components to replace old, wears out  life span is 100-120 days  macrophages phagocytose worn out RBC’s in the spleen, liver and bone marrow  normally the rate of production of new erythrocytes equals the rate of destruction of the old ones  2-3 million new RBC’s enter the blood stream per second the haemoglobin inside the RBC’s being destroyed is broken The iron from haem is recycled to make new Haemoglobin The rest of the haem is degraded to the yellow pigment bilirubin, which is excreted via the intestine in bile. Globin is broken down into amino acids and released into the bloodstream

Erythropoiesis  production of red blood cells from precursor stem cells

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Dietary requirements

white blood cells (leukocytes)  support the immune system, several different types  These make up less than 1% of total blood volume  These are cells of the immune system, providing defence against infection and other foreign bo  Can leave the bloodstream and move to site of infection leucocyte rolling - There are several different type Neutrophils make up 40-75% of leukocytes  Also known as Polymorphonuclear leukocytes due to the variable shapes of their nuclei.  Very active against bacteria. Move towards them by chemotaxis– first to arrive and very phago chemotaxis  Pus consists of dead neutrophils, microbes, cell fragments and wastes  Short life span of 30 min -10 hours -

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Eosinophils make up 1-6% of leukocytes  Red-staining, bilobed nuclei  Digest parasitic worms that are too large to be phagocytosed  Also found at sites of allergic reactions eg airways, skin  Modulators of the immune response – help REDUCE inflammation

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Lymphocytes make up 20-50% of leukocytes  Large, dark-purple, circular nuclei with a thin rim of blue cytoplasm  Mostly in lymphoid tissue; few circulate in the blood  Crucial to SPECIFIC immunity  Three types: T cells (active against virus-infected & tumour cells) B cells (antibody production) Natural killer cells (cytotoxic)

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Monocytes make up 2-10% of leukocytes  The largest leukocytes.  Dark purple kidney shaped nuclei with abundant pale-blue cytoplasm.  Actively motile and phagocytic - crucial against viruses, intracellular bacterial parasites, and ch

Understand the stages of haemostasis and their purpose. Fast series of reactions to stop bleeding: 1. Vascular spasm - Vasoconstriction by damaged blood vessel - Triggers include Direct injury Chemicals released by damaged vessel walls and by platelets Pain reflexes 2. Platelet plug formation -

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Rapid positive feedback cycle. At site of blood vessel injury, platelets stick to exposed collagen fibres They swell, become spiked and sticky, and release chemical messengers to attract more platelets. Platelets form a temporary plug that helps seal the blood vessels. Coagulation (blood clotting) Complex set of reactions Involves positive feedback. Blood is transformed from a liquid to a gel Reinforces the platelet plug with fibrin threads. There are two pathways: extrinsic pathway (tissue factor) intrinsic pathway (contact activation)

Clot retraction and repair RETRATION - Actin and myosin in platelets contract within 30–60 minutes. - Platelets pull on the fibrin strands, squeezing serum from the clot. REPAIR - Platelet-derived growth factor (PDGF) stimulates division of smooth muscle cells and fibroblasts to reb - Vascular endothelial growth factor (VEGF) stimulates endothelial cells to multiply and restore the end

Fibrinolysis - Begins within two days - Plasminogen in clot is converted to plasmin - Plasmin is a fibrin-digesting enzyme

BLOOD DISORDERS Erythrocytes disorders:

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Treatments include irradiation, cytotoxic drugs and stem cell transplants

PLATELET DISORDERS -

Thrombocytopenia  decreased platelet numbers resulting in bleeding Thrombocytosis  increased platelet numbers, result In clotting within blood vessels (thrombosis)

Haematocrit - Percentage of whole blood occupied by red blood cells - The remaining formed elements make up the thin buffy coat layer...