1.1 Blood, erythrocytes Flashcards
describe the physical characteristics of blood
- colour: scarlet (O2 bound) to dark red (deoxygenated aka venous blood)
- pH: 7.35 (venous) - 7.45 (aterial, less CO2 so less acidic)
- temp: 38 C
- blood accounts for 8% of body weights
- Average volume: 5-6 L for males, and 4-5 L for females
composition of blood
composed of liquid plasma and formed elements
Formed elements include:
- Erythrocytes, or red blood cells (RBCs)
- Leukocytes, or white blood cells (WBCs)
- Platelets
at is hematocrit
percentage of RBCs out of the total blood volume
*females have lower hematocrit
what is in blood plasma
*90% water
- 6-8% proteins: albumin, globulins, clotting proteins, and others
- 2-3% other icnldues over 100 diff solutes:
- Organic: carbohydrates, amino acids, fats, lactic acid, urea, creatinine
- Electrolytes: Na+, K+, Ca2+, Cl-, bicarbonate
- GasesL O2 an CO2
- hormones
descirbe improtance and role of diff plasma proteins in blood
- all contribute to osmotic pressure and maintain water balance in good and tissues
*susually dont leave blood stream, they pull fluids out of tissues back into capillary beds
- Albumin
- 60% of palsma proteins
- carry Fas and formones
- Glogulins
- contain alpha, beta and gamma
- alpha and beta: important for binding and transport of fat soluble thigns
- gamma: AKA antibodies, released by palsma cells during immune response
- contain alpha, beta and gamma
- Fibrinogen
- 4%
- precursor in coagulation pathway
onyl ___ are complete cells
WBC
aka have a nucleus
*RBC have no nuclei or organelles, and platelets are just cell fragments
What are erythrocytes
- Biconcave discs, anucleate, essentially no organelles
- Filled with hemoglobin (Hb) functions in gas transport
- Most oxygen in the blood is bound to Hb
what is the purpose of the unqiue structure of erthyrocytes
RBCs have resilient and flexible shape
- spectrin linked to cytoplasm slide and allow them to change shape
- biconcave shape: large surface area relative to volume
- eryhtocytes are more than 97% hemoglobin
- ATP is generated anaerobically
role of heme group
- has a central iron atom that can bind to one O2
- each Hb molecule can transport 4 O2
- hemoglobin has 4 heme groups and 4 polypeptides (two alpha dn two beta chains)
describe production of erthrocytes depending on age
•Yolk sac phase - blood in ‘islands’ in yolk sac, no leukocytes (In first few monthf of fetus)
- Hepatic/spleen phase - primitive nucleated RBCs, fetal Hb
- Bone marrow phase - mature RBCs, leukocytes, ~12 weeks (closer to birth)
• Adult phase - made in axial skeleton and distal long bones (pelvis, vertebrae, skull, ribs, ends of long bones)
What is Erythropoiesis
- development of erythrocytes
- has 3 phases: Stem cell (hemocytoblast), committed cell (proerythroblast), developmental pathway
*developmental pathway has 3 phases: ribosome syn -> hemoglobin accumulation -> ejection of nucleus
WHat regualtes eryhtropoiesis
- process reuqires: Proteins, lipids, carbohydrates, Iron, vitamin B12 and folic acid
*FOlic acid is Vit B9, important for rapid DNA syn)
- body stores stores iron in Hb (65%), the liver, spleen, and bone marrow
how is iron found inside cell vs inside blood
- instracellular iron is stores in protein-iron complexes like ferrritin and hemosiderin (important for bidngin iron inside cells)
- ciruclating iron is loosely bound to transport protein transferrin (in blood stream not in cell)
steps in regulation of Erythroproeisis
- Low O2 levels in blood stimulate kidneys to produce erythropoietin (EPO)
- EPO levels rise in blood
- EPO and necessary raw materials in blood promote erythropoiesis in red bone marrow
- Newerythrocytes enter bloodstream; function ~120 days
Describe the rpocess of breaking down aged/damaged RBCs
Aged and damaged RBC are engulfed by macrophages of liver, spleen, and bone marrow; the hemoglobin is broken down
- Hemoglobin -> heme and globin
- globin is broken down into tis amino acids and enters blood
- heme is broken down into iron (stored as ferritin, hemosiderin) and billirubin
- Bilirubin picked up from blood by liver -> secreted into intestine in bile -> metabolized to stercobilin by bacteria -> feces
- Iron found to transferrin and released to blood from liver as needed for erythropoiesis
