Blood Physiology 1 Flashcards
(28 cards)
What type of tissue is blood?
connective tissue
Differentiate between whole blood and peripheral blood
Whole blood:
blood contained in cardio system, including heart, arteries and veins
peripheral blood:
whole blood circulating in arteries and veins
What are the functions of blood?
1) Transportation:
O2, nutrients, waste, hormones, platelets
2) Regulation:
Body temp., tissue fluid content, blood pH
3) Defence system:
WBC, phagocytes, platelets
What cellular and non-cellular components make up blood?
Cellular:
1. RBC,
2. WBC:
- phils: neutro, eosino, baso
- cytes: lympho, mono
3. Platelets (thrombocytes)
Non-cellular:
- Plasma: intravascular component of ECF (+- 20%)
What % of blood is composed of plasma, and what is plasma composed of?
55%
PLASMA =
91% water
7% proteins
2% other solutes
Differentiate between plasma and serum
plasma:
Whole blood, excluding cells. Part of ECF and contains plasma proteins
Serum:
whole blood excluding cells and clotting factors (plasma without clotting factors)
What plasma proteins are there?
All plasma proteins except gamma globulins are made by the liver.
1) Albumin (most abundant) = colloid osmotic/ oncotic pressure + transport proteins for steroid hormones + fatty acids
2) Globulins:
alpha
> transport protein (Copper, cortisol)
> inflammation
> clotting
beta
> transport protein (iron, lipids, fat-soluble vitamins)
gamma: made by B-lymphocytes
> immunoglobulins = immunity
3) Fibrinogen = blood clotting
Describe hematopoiesis
blood cell production: stem cell → mature blood cell
continuous process:
→ Initiates in yolk sac of embryo
→ developing organs of foetus (spleen, liver, thymus, lymph nodes)
→ red bone marrow (before birth & throughout life)
→ extramedullary (outside bone marrow) in emergencies in adults:
liver, spleen
What is erythropoiesis?
▪ process of making RBC
▪ erythropoietin (EPO) released from cells in kidney in response to hypoxia
▪ regulated by hormones
What are the different types of leukopoiesis
Formation of WBC
▪ lymphopoiesis → lymphocytes
▪ monopoiesis → monocytes
▪ granulopoiesis → neutrophils, basophils, eosinophils
▪ regulated by cytokines
Briefly describe the process of thrombopoiesis
Produce platelets
unipotential stem cell → megakaryocyte → pieces of cytoplasm break off as platelets
▪ regulated by thrombopoietin
Describe the structure of a RBC
mature RBC:
▪ non-nucleated (except in avians)
▪ biconcave disks with thinner central zone:
→ deformable
– squeeze through
capillaries
→ greater surface area
– optimal diffusion
▪ NO mitochondria + ribosomes
▪ cytoskeleton: actin/ spectrin/ ankyrin forms meshwork with high tensile strength and flexibility
Composition of a RBC
1) Water (65%)
2) Solids (35%)
= 95% Haemoglobin > carry O₂ + CO₂
= 5% membrane proteins, lipids,
enzymes >
▪ Carbonic anhydrase > pH regulation
(buffering)
▪ Glycolytic enzymes > ATP
Describe the structure haemoglobin
1 Hb = 4 subunits (4 polypeptide chains)
1 subunit = globin + haem molecule
globin = alpha/ beta chain = binds CO₂
haem = 1 iron binding site
1 Fe²⁺ binds 1 O₂ = oxyhaemoglobin
thus 1 Hb binds 4 O₂ molecules
[ NOTE:
→ iron binds reversibly to O₂ in its Ferrous form = Fe²⁺
→ binding to ferric iron (Fe³⁺) is non-functional in Hb = methaemaglobin]
Functions of haemoglobin
= allows RBC to carry gasses:
- carrier of oxygen
- carrier of carbon dioxide
(± 23% of all CO₂)
= buffer
(CO₂ + H₂O ↔ H₂CO3 ↔ H+ + HCO3-)
Describe the difference interaction between CO₂ VS CO and Hb
Carbon dioxide (CO₂) and Hb:
▪ does not attach to iron but rather globin
Carbon monoxide (CO) and Hb:
▪ binds to iron to form carboxyhaemoglobin
▪ stronger binding than O₂ → reduces O₂ carrying capacity
[competes with O₂ for its binding site]
Briefly describe effect of Hb binding to ferric iron i.s.o ferrous iron
When hemoglobin (Hb) binds ferric iron (Fe³⁺) instead of its normal ferrous form (Fe²⁺), it forms methemoglobin (MetHb).
Fe³⁺ cannot bind O₂ thus non-functional for O₂ transport and leads to methemoglobinaemia
What is a senescent cell? What does senescence mean
aged cell
senescence = process of aging
Differentiate between intra and extravascular haemolysis
Intravascular: Destruction of RBCs within the blood vessels, releasing hemoglobin directly into the bloodstream.
10% of senescent RBC
Extravascular: Destruction of RBCs outside the blood vessels, primarily by macrophages in the spleen, liver, and bone marrow
90% of senescent RBC
Describe what happens during intravascular haemolysis
1) Cell membrane ruptures
2) Hb released into blood stream
3) Hb binds to haptoglobin
4) Goes to liver for further breakdown via macrophages
NOTE: if there is too little haptoglobin to bind Hb, the excess Hb circulates in the blood = haemoglobinaemia
> free Hb is filtered by the kidneys and eliminated in the urine = haemoglobinuria = dark red/ brown colour
Describe what happens during extravascular haemolysis
1) RBC recognised, engulfed and broken down by macrophages
2) RBC Cell membrane ruptures
3) Hb released
4) Hb broken down:
i) globin → amino acids > liver >
reused to build proteins
ii) Fe²⁺ → bone marrow > recycled
during erythropoiesis
iii) haem → bilirubin > attaches to albumin > liver > conjugated to glucuronic acid > excreted in bile into small intestine > converted to urobilinogen by bacteria > excreted in urine as urobilin or in faeces as stercobilin
What leads to icterus/ jaundice?
excessive accumulation of bilirubin in the blood and tissues – yellow pigmentation
▪ most easily seen in the gingivae (gums), the sclerae and the pinnae
Differentiate between pre-hepatic, hepatic and post-hepatic jaundice
▪ pre-hepatic: before the liver
→ increased haemolysis and hence build-up of bilirubin
→ may occur as a result of toxic plants, drugs, parasites, autoimmune diseases, cancer
▪ hepatic: in the liver
→ damage to liver tissue
→ may occur due to viral or bacterial infections, ingestion of toxic plants or chemicals, certain drugs and medications, cancer, autoimmune diseases, certain breed-specific liver diseases
▪ post-hepatic: after the liver
→ obstructive jaundice - bilirubin can’t be drained properly into the bile ducts or digestive tract because of a blockage
→ pancreatitis, abdominal trauma, abdominal or liver cancer, gall bladder stones
when in doubt say cancer
Briefly discuss the steps of iron metabolism
Iron enters the cell either as non- haem/ haem iron:
Non-haem iron = Fe²⁺/ Fe³⁺:
Fe³⁺ is first reduced to Fe²⁺ > Fe²⁺ enters the cell > is either stored in ferritin or exported out of the cell via ferroportin > exported Fe²⁺ is oxidized to Fe³⁺ by Hephaestin > Fe³⁺ binds to Transferrin and is transported to cells with transferrin receptors (liver/ bone marrow)
Haem - iron:
haem molecule is broken down by haem oxygenase > same as before
