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Homeostasis lecture 2- Blood

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winniesmith1's version from 2017-02-26 14:40

Section 1

Question Answer
What is blood/ what does it containspecialized fluid of connective tissue. Contains cells suspended in a fluid matrix. Plasma: fluid. Formed elements: all cells and solids.
General characteristics of the whole blood38*C (normal temp). High viscosity- of 5.0 (5x more than water). Only flows under high pressures. Slightly alkaline pH (7.35.-7.45)
What % body weight is blood volume7%
How many litres of blood in the adult male5-6 litres
How many litres of blood in the adult female4-5 litres
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Section 2

Question Answer
What are the functions of the bloodTransportation, Regulation, Protection, Restriction
What does the blood transport* Respiratory substances, oxygen and carbon dioxide * Nutritive substances, products of digestion. * Excretory substances, e.g. excess water and salt
What does the blood regulate* Hormones and regulatory molecules to target tissues * pH and electrolyte composition of interstitial fluid * Thermoregulation, stabilization of body temperature
How does the blood protect the body * Defence against toxins and pathogens * Clotting of damaged vessels
How does the blood allow restriction* of fluid losses at injury sites.
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Section 3

Question Answer
What is the blood composed ofplasma (55%) and formed elements
What is plasma made up ofFluid consisting of water (92%), dissolved plasma proteins (7%) other solutes (1%)
What are the formed elements -All cells and solids -Red blood cells (RBC) White blood cells (WBC) Platelets
What makes up the plasma proteinsAlbumins, Globulins, Fibrinogen, Regulatory proteins.
What makes up the other solutes in plasmaElectrolytes, organic nutrients and organic wastes.
What makes up the formed elements (45%)Platelets, white blood cells, red blood cells(99.9%)
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Section 4

Question Answer
What is Red blood cell countreports the number of RBCs in 1 microliter of whole blood.
What is the average rbc count for males and femalesmales: 4.5-6.3 million; females 4.2-5.5 million.
What is haematocrit (packed cell volume, PCV)the ratio of the volume of red blood cells to the total volume of blood / % of RBCs in centrifuged whole blood (males: 40-54; females: 37-47)
Why is the size and shape of RBCs important High surface-to-volume ratio: quickly absorbs and releases oxygen. Discs form stacks (rouleaux): smoothes flow through narrow blood vessels. Discs bend and flex entering small capillaries: 7.8 µm RBC passes through 4 µm capillary.
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Section 5

Question Answer
What is RBC production called Erythropoiesis
Where does Erythropoiesis occuronly in red bone marrow (myeloid tissue)
What happens in Erythropoiesis maturationStem cells mature to become RBC's. The stem cells in the bone marrow divide to produce myeloid stem cells; become RBCs, and some WBCs. Lymphoid stem cells: become lymphocytes.
What is the lifespan of RBCsabout 120 days.
Why is the lifespan of RBCs so low As they don't have nuclei, mitochondria and ribosomes. This means that there is no repair and no anaerobic metabolism.
How are RBCs recycled1% of circulating RBCs wear out per day: (3 million RBCs /second) Macrophages of liver, spleen, and bone marrow: monitor RBCs engulf RBCs before membranes rupture (hemolyze)
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Section 6

Question Answer
Why is blood red?Due to haemoglobin pigment.
What is Haemoglobin?Protein molecule that transports respiratory gases (binds and transports 02 and C02).
What are normal Hb values in adults?male: 14-18 g/dl whole blood. female- 12-16 g/dl
What is the structure of haemoglobin4 globular protein subunits: each with 1 molecule of heme each heme contains 1 iron ion
What do iron ions do associate with oxygen (to form oxyheamoglobin) or dissociate from oxygen (deoxyhaemoglobin)
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Section 7

Question Answer
What are leukocyteswhite blood cells
What do leukocytes containHave nuclei and other organelles but not have haemoglobin.
What are the functions of leukocytesDefend against pathogens, remove toxins and wastes, attack abnormal cells.
How do leukocytes workmigrate out of bloodstream, attracted to chemical stimuli (positive chemotaxis) and have amoeboid movement
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Section 8

Question Answer
What are the 5 types of WBCsNeutrophils, Eosinophils, Basophils, monocytes (all non specific defence) and lymphocytes (specific immunity).
What are neutrophils Also called polymorphonuclear leukocytes -50–70% of circulating WBCs -Pale cytoplasm granules with: lysosomal enzymes - bactericides (hydrogen peroxide and superoxide)
What do neutrophils doVery active, first to attack bacteria -Engulf pathogens -Digest pathogens -Release prostaglandins and leukotrienes -Form pus
What are eosinophils Also called acidophils -2–4% of circulating WBCs -Attack large parasites -Excrete toxic compounds: nitric oxide cytotoxic enzymes - Are sensitive to allergens -Control inflammation
What are basophils Are less than 1% of circulating WBCs. Accumulate in damaged tissue. Release histamine and heparin.
What does histamine doDilates blood vessels
What does heparin doStops blood clotting
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Section 9

Question Answer
What are monocytes2–8% of circulating WBCs. Enter peripheral tissues and become macrophages. Engulf large particles and pathogens. Secrete substances that attract immune system cells and fibroblasts to injured area.
What are lymphocytes20–30% of circulating WBCs. Migrate in and out of blood. Mostly in connective tissue and lymphoid organs. Are part of the body’s specific defense system.
What are the 3 types of lymphocytes T cells: attack foreign cells directly. B cells: synthesize anti-bodies. Natural killer (NK) cells: detect and destroy abnormal tissue cells (cancer cells).
What are platelets Cell fragments involved in human clotting system. Smallest cells within the formed element portion of blood. Lack nuclei
How long do platelets lastCirculate for 9-12 days, removed by spleen, 2/3 are reserved for emergencies.
What is the average platelet count150,000 to 500,000 per 1 microliter of blood
What is abnormally low platelet count Thrombocytopenia
What is abnormally high platelet countThrombocytosis
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