blood and organs Flashcards
main components of blood
plasma
platelets
red blood cells
white blood cells
what is plasma
liquid which carries everything that needs transporting around your body
what six things does plasma carry
blood cells
digested food products
carbon dioxide
urea
hormones
heat energy
what are platelets
platelets clot the blood in a wound, held together by a mesh of fibrin
what do red blood cells do
transport oxygen from the lungs to all cells
what adaptations do the red blood cells have
biconcave cell
no nucleus
contain haemoglobin
thin membrane
how does haemoglobin aid red blood cells
in the lungs haemoglobin reacts with oxygen to become oxyhaemoglobin, in body tissue the reverse happens to release oxygen into the cells
how do pathogens cause disease
once entered the body they reproduce rapidly
2 types of white blood cells
phagocytes
lymphocytes
how do phagocytes kill pathogens
engulf and digest pathogens
they are non-specific so they attack anything foreign
how do lymphocytes kill pathogens
lymphocytes produce proteins called antibodies, they lock onto the pathogen and mark them for destruction
what are memory cells
produced in response to a foreign antigen, remain in the body and remember a specific antigen, building immunity
how do vaccines protect from future infection
injects dead pathogens into the body, carrying antigens, these trigger an antibody attack from lymphocytes. the memory cells ensure that if they appear again, the antibodies will kill them
3 different types of blood vessels
arteries
capillaries
veins
what is the function of arteries
carry the blood away from the heart
what is the function of capillaries
involved in exchange of materials at the tissue
what is the function of veins
carry blood to the heart
why are artery walls strong and elastic
heart pumps blood at high pressure
features of arteries
thick, strong elastic walls with elastic fibres allowing the arteries to expand
features of capillaries
walls only one cell thick
permeable walls
microscopic
why are capillary walls permeable
so that substances can diffuse in and out such as food, oxygen and CO2
why are the walls only one cell thick
increases rate of diffusion by decreasing the distance over which it occurs
features of veins
thinner walls than arteries
bigger lumen
valves
why do veins have thinner walls than arteries
blood is at lower pressure
why do veins have a bigger lumen
helps the blood flow
why do veins have valves
to keep the blood flowing in the right direction
what occurs in the right atrium
receives deoxygenated blood from the body through the vena cava