5.1 - Blood as a transport medium

5.1

What is the structure of the blood with percentages

plasma - 55%
formed elements - 45%

• erythrocytes - 41%

• leucocytes - 1%

• platelets

What is plasma

a mixture of water and dissolved sugars + salts

what is plasma’s main function

transporting compounds of blood throughout the body

what is the word for the percentage of red blood cells in the blood

haematocrit

why dont red blood cells have a nucleus

to increase their flexibility and to make room for haemoglobin molecules

what is the shape of a red blood cell

bioconcave shape to increase SA for oxygen exchange and thick edges to allow room for haemoglobin molecules

what is the lifespan of a red blood vessel and why

120 days because they have no nucleus

what is the main role of the red blood cells

oxygen transport

what is the main role of the white blood cells

protect body from infection

neutrophils

granulocyte - contains pathogen digesting enzymes

monocytes

agranulocyte - form other cells that engulf pathogens and damaged cells with phagocytosis

lymphocytes

agranulocytes - T lymphocytes are cell mediated immune response, B lymphocytes are antibody mediated

Basophils

granulocytes - produce heparin and histamine for allergic reactions

Eosinophils

granulocytes - respond to larger parasites like worms

What are thrombocytes

fragments of cells

what do thrombocytes do

adhere to lining of injured vessel to form scaffold for coagulation of blood to form a clot

how is oxygen carried (%)

3% in plasma, 97% in haemoglobin

what is it called when oxygen binds with haemoglobin

oxyhaemoglobin

is the bond between haemoglobin and oxygen strong or weak and why

it is loose so it can be broken down easily to release oxygen

by how many times does the presence of haemoglobin increase the carrying capacity for oxygen in the blood

60-70 times

how does haemoglobin work

• oxygen combines when its concentration is high

• tissue fluid around cells have low oxygen concentration

• oxyhaemoglobin breaks down when oxygen concentration is low

what are the differences in colour between oxygenated and deoxygenated blood

oxyhaemoglobin is bright red so oxygenated blood is bright red in arteries (aside from pulmonary arteries)
deoxygenated blood is dark red in veins (aside from pulmonary veins)

how is carbon dioxide stored in the blood

• 8% dissolved in plasma

• 22% combines with the globin in haemoglobin to form carbamniohaemoglobin

• 70% carried in plasma as bicarbonate ions

how is carbon dioxide let into the bloodstream

• diffuses into plasma through capillaries due to concentration difference

• some dissolves into plasma and some combines to haemoglobin

• most reacts with water to form carbonic acid

  • this ionises into hydrogen ions and bicarbonate ions

how is carbon dioxide released

• diffuses out of blood into alveolus

• carbaminohaemoglobin breaks down

How are nutrients transported in the blood

inorganic are transported as ions, organic are dissolved in plasma

what are examples of metabolic wastes

urea, creatine, uric acid

what are the four steps of blood clotting

• vasoconstriction

• platelet plug

• coagulation

• scab

what happens in vasoconstriction

muscles in walls of small arteries constrict to reduce bloodflow

How does a platelet plug work

platelets stick to rough damaged walls and attract each other to form plug

release vasoconstrictors to prolong constriction

how does coagulation work

clotting factors form fibrin, which forms a mesh called thrombus to trap cells, plasma, and platelets

how is the scab formed

serum is released when threads contract together and get denser, and the clot dries out to form a scab