Blood (10) Flashcards
How does blood move through the heart?
1) Blood leaves heart through arteries which branch into arterioles which branch into capillaries
2) O2 and nutrients leave blood by diffusing across capillary walls to tissues and CO2 moves from the tissues into the bloodstream
3) O2 deficient blood then leaves capillaries and flows into veins which branch into venules which then return this blood to heart
4) Blood flows from heart to lungs to be oxygenated and then returns to heart again
What side of the heart does oxygenated blood flow?
Left
What side of the heart does oxygenated blood flow?
Left
What side of the heart does deoxygenated blood flow?
Right
What is the blood composed of?
> It’s the body’s only fluid tissue
It’s a specialised connective tissue in which living blood cells (formed elements) are suspended in a non-living fluid called plasma
Formed elements include; erythrocytes, leucocytes and thrombocytes
What are the characteristics of blood?
1) Sticky opaque fluid with a metallic taste
2) Colour varies depending on oxygenation- scarlet= O2 rich, dark red= O2 poor
3) Denser than water and 5x more viscous (because it contains formed elements)
4) Slightly alkaline (pH 7.35-7.45)
5) 8% of TBW
6) Males 5-6L, females 4-5L
Functions of blood- distribution
> Delivers O2 from lungs and nutrients from digestive tract to all body cells
Transports metabolic waste products from cells to sites of elimination e.g. lungs to eliminate CO2, kidneys to eliminate waste in urine.
Transports hormones from endocrine organs to target organs
Functions of blood- regulation
> Maintains body temp absorbing and distributing heat throughout body
Maintains pH in tissues- bloodborne proteins act as buffers to stabilise pH
Maintains fluid volume- plasma proteins prevent excessive fluid loss from bloodstream into tissue spaces
Functions of blood- protection
> Prevents blood loss- when vessels damaged, platelets and plasma proteins initiate clot formation, stopping blood loss
Prevents infection- Antibodies, complement proteins and white blood cells help to protect body from bacteria and viruses
What is blood plasma?
> Straw-coloured, sticky fluid
90% water and over 100 different dissolved substances:
1) Proteins- albumin, globulin, clotting proteins
2) Nonprotein nitrogenous substances- lactic acid, urea, creatine
3) Nutrients- glucose, carbohydrates, amino acids
4) Electrolytes- sodium, potassium, calcium, chloride, bicarbonate
5) Respiratory gases- O2 and CO2
What are the 3 formed elements?
1) Erythrocytes (not true)
2) Leucocytes (complete cell)
3)Thrombocytes (not true)
> Erythrocytes not true cells as have no nuclei/organelles and thrombocytes are not true cells as they are only cell fragments
> Have short shelf-life (some only few days)
> Most blood cells don’t divide, instead stem cells in red bone marrow continuously divide to replace them
What are erythrocytes?
> Most abundant (99%)
7.5um diameter
Biconcave discs
Anucleate
Contain bags of haemoglobin- a protein which has functions in gas transport
Contains the protein spectrin- a deformable network which allows erythrocytes to change shape
Small size and shape provides huge SA for gas exchange
Do not consume any O2 that they carry as they don’t have mitochondria- very efficient
Major contributing factor to viscosity
Male= 4.7-6.1 million/L female= 4.2-5.4 million/L
Haemoglobin binds easily and reversible to O2 and carries most of the O2 in the bloodstream
Lifespan= 100-120 days
As they age, become rigid and fragile and haemoglobin begins degenerating
Dying ones engulfed by macrophages- haem and globin seperated
Female Hb= 11.5-16.5 g/100ml blood
Male Hb= 13-18 g/100ml blood
What is anaemia?
> Insufficient erythrocytes
Reduction in O2 carrying capacity of blood
Haemorrhagic anaemia= result of actuate/chronic blood loss
Haemolytic anaemia= Prematurely ruptures erythrocytes
Aplastic anaemia= destruction/inhibition of red bone marrow
Sickle cell anaemia= Abnormally shaped erythrocytes which stick together and form clots
What are the functions of leucocytes?
1) Defence against infection
2) Immunity
3) Antigen-antibody reactions
4) Allergies
5) ABO blood grouping
6) Graft versus host disease- when body recognises own cells as foreign
What are leucocytes?
> White blood cells
The only formed element that is a complete cell (has a nucleus and organelles)
Less than 1% of blood volume
Defend body against bacteria, viruses, parasites, toxins and tumour cells
Can leave bloodstream by diapedesis (through walls of blood vessels)
2 types- granulocytes (neutrophils, eosinophils and basophils) and agranulocytes (monocytes and lymphocytes)