Chapter 17 Part 1 Blood) Flashcards
1
Q
Blood
A
Life-sustanining transport vehicle of the Cardiovascular System
- Transport function
- Devivering O2 and nutrients to body cells
- Tranport metabolic waste to lungs and kidneys
- Tranport hormones from endocrine organs to target organs
- Regulation Functions
- Mantaining body temp by absorbing/distributing heat through skin and blood vessels
- Mantaining normal pH using Buffers
- Mantaining aqeute fluid volume in circuitory system (endocrine function mostly)
- Protection Functions
- Preventing Blood Loss; protiens and platlets form clots
- Preventing Infection: Immune componants are carried in the blood (antibodies, WBC’s and Compliment protiens)
2
Q
Composition of Blood
A
Only Fluid tissue in the body. Technically a type of Connective Tissue
- Matrix) Nonliving fluid called plamsa
- Cells) Living blood cells are called formed elements
- Suspended in plasma
- Include Erythocytes (red blood cells, RBC’s), Lukeocytes (white blood cells, WBC’s) and Platlets.
- Blood spun in a centrafuge
- Eythrocytes will be on the bottom (~45% compisition)
- Hematocrit) percent of blood volume that is RBC’s
- (47%± 5% in males) (42% ± 5% in females)
- WBC’s and platlets in Buffy Coat (<1% compisition)
- middle layer
- Plasma is on top (~55%)
- Eythrocytes will be on the bottom (~45% compisition)
3
Q
Physical Characteristics and Blood Volume
A
- Blood is sticky, opaque fluid with metalic taste
- Color Varries with O2 content
- High O2) Scarlet, bright red
- Low O2) Dark red color
- pH stays within 7.35-7.45
- Makes up about ~8% of total body wight
- Blood Volume
- Males) 5-6 liters
- Females) 4-5L
4
Q
Blood Plasma
A
- A Straw-colored sticky fluid
- about 90% is water
- Composed of over 100 dissolved solutes
- Nutrients, gases, hormones, wastes, protiens, inorganic ions.
- Plasma protiens are most abundent solutes
- Plasma Protiens
- Remain in the blood; not uptaken by cells
- Produced mostly by liver
- Albumin: Maked up to 60% of plasma protiens
- Functions as a carrier of other molecules, blood buffer (pH) and contributes to plasma osmotic pressure.
5
Q
Formed Elements
A
- Formed elements are RBCs, WBCs, and platelets
- Only WBCs are complete cells
- RBCs have no nuclei or other organelles
- Platelets are cell fragments
- Most formed elements survive in bloodstream only few days
- Most blood cells originate in bone marrow and do not divide
6
Q
Erythocytes (RBC’s)
A
- RBCs are small-diamater (7.5 nanometer) cells that trasnport gas
- Cell is a biconcave disc shape, anuclete (no nucleus) and has essentally no organelles
- Hemoglobin (Hb) involved in gas transpoet
- Can be larger than some capillaries
- Plasma membrane protiens
- Spectrin) Mantains biconcave shape of erythocyte but allows it to change shape to move through small spaces (capillaries)
7
Q
Hemoglobin Structure
A
Hemoglobin binds reversibly with O2
- Consists of red Heme pigment bound to Protien Globin
- Globin is composed of four polypeptife chains
- Two alpla and two beta chains
- Heme pigment is bonded to each globin chain
- gives blood red color
- Each heme’sc central iron atom bonds one O2
- Each Hb molecule can transport four O2
- Each RBC contains 250 million HB molecules
- O2 Pathways
- O2 loading in the lungs produces oxyhemoglobin (ruby red and oxignated
- O2 unloading in tissues produces deoxyhemoglobin (dark red reduced O2)
- CO2 loading in tissues (as waste) produces Carbaminohemoglobin
- 20% of CO2 in blood binds to Hb
8
Q
Production of Erythrocytes
A
- Hematopoiesis) Formation of all blood cells.
- Occurs in Red Bone Marrow
- found in axial skeleton, girdles, and proximal epiphyses of humerus and femur.
- Hematopoietic Stem Cells (hemocytoblasts) stem cell that gives rise to all formed elements
- Erythropoiesis) proccess of RBC formation that takes about 15 days
- Hematopoietic Stem Cell > Myeloid Stem Cell
- Myeloid Stem Cell > Proethroblast (a commited stem cell)
- Proethryoblast will eject its organelles and degrade its nucleus and becomes a mature erythocyte in about 2 dayys.
9
Q
Regulation and Requirments of Erythopoiesis
A
- Too few RBC’s leads to hypoxia
- Too many RBC’s increases blood visocisty
- >2 million RBC’s are made per second
- Blance between RBC production and destruction depends on Hormonal Controls and Dietary Requirments
- Hormonal Control
- Ertyhropoietin (EPO) the hormone that stimulates formation of RBC’s
- There is always a small ammount of EPO in the blood to mantain basal rate
- Released by Kidneys in Response to Hypoxia
- Diatery Requirments
- Needs amino acids, lipid, and carbs as well as iron from diet.
- 65% of iron is found in hemoglobin and the restis found in the liver, spleen and bone marrow.
- Free iron is toxic so it is bound with the proteins Ferritin, Hemosiderin, and
- transfered in blood via the protein Transferrin.
10
Q
Causes of Hypoxia
A
- Hypoxia) there is not adquete oxygen levels avaible.
- Causes
- Decreased RBC numbers die to hemmorage or increased destruction.
- Insufficent hemoglobin per RBC (iron deficiency)
- Reduced availability of O2 (altuide, lung problems such as pnemonia)
11
Q
Destruction of Erythocytes
A
- Lifepan is about 100-120 days. because RBC’s are anucleate they do not grow or divide.
- Old RBC’s
- are fragile and Hb begins to degenerate
- Get trapped in spleen where macrophages break down and engulf
- RBC Breakdown
- Iron, Heme, and globin are seperated
- Iron binds to ferritin or hemosiderin and is then stored for reude
- Heme is degraded into bilribin (bile pigemt) and is secrteted into intestines. (urobilinogen > Sterocobilin)
- Globin is metabolized into amino acids that are released into blood circulation
12
Q
Anemia
A
- Blood has abnormally low O2 carrying capacity that cannot support normal metabolism
- Caused by Blood loss, Not enough RBC’s being produced, or too many RBC’s being destroyed.
- Not Enough RBC’s being produced
- Iron-Deficiency Anemia) low iron intake or absorbtion
- RBC’s produced are small and called microcytes
- Pernicious Anemia) Stomach mucosa that produces intrnsic factor is destrpyed. Intrensic Factor produced vitaman B12 which helps RBC’s divide
- RBC’s cannot devide resultng in larfe macroctyes.
- Renal Anemia) lack of EPO
- Iron-Deficiency Anemia) low iron intake or absorbtion
- To Many RBC’s destroyed. (premature lysis or gemolytic anemias)
- Thalassemias) One globulin chain is missing/faulty. RBC’s are thin, delicate and defficent in hemoglobin
- Sickle-Cell anemia) Contain hemoglobin S (mutated hemoglobin). One amino acid chain is wrong which results in mishapen RBC’s when O2 levels are low
13
Q
Polycythemia
A
- Abnormal excess of RBC’s
- increases blood viscosity which causes sluggish flow
- Polycythemia Vera) Bone marrow cancer leading to excess RBC’s
- Secondary Polycyhtemia) caused by low O2 levels or increaded EPO
14
Q
Lukeocytes (WBC’s)
A
- Only Formed element with complete cell (nuclei and organelles)
- Make up <1% of blood volume
- Function to defend against desiese
- Can leave capillaries via diapedesis
- move through tissue spaces via amoeboid motion and positivr chemotaxis
- Lukeocytosis) Increase of WBC’s which is a response to infection
- Two major Catagories
- Granulocytes: contain visible cytoplasmic granules (neutrophils, eosinophils, basophils)
- Agranulocytes: do not contain visible cytoplasmic granules (lymphocytes, monocytes)
- “Never let monkeys eat bananas” is memonic for number in body
15
Q
Granulocytes
A
- Larger and shorter-loved than RBC’s. Lobed nuclei and phagocytic to some degree
- Neutrophils) Most numerous WBC’s
- Contain hydrolytic enzymed or antomicrobial proteins.
- Defensins) 3-6 lobes in the nucleus.
- Very phagocytic- “Bacteria slayers”. Kill by injecting oxidizing substances (bleach or hyrrogen peroxide)
- Eosinophils) Bilobed nucleus
- release enzymes to digest parasitic worms, role in allergies and asthma
- Basophils) Rarest WBC
- Bilobed nucleus and large purplish cytoplamic granules
- Gransules contain histamine; and inflamatory chemical that acts as a vasodilator to attract WBC’s to inflamed sites.
- Functionally similar to mast cells.
