2H TRANSPORT IN HUMANS

what is the composition of blood

55% plasma

45% red blood cells

<1% white blood cells/platelets

what is plasma

a straw coloured liquid which the other components of the blood are suspended iwthin

what can plasma transport

• co2 transported from respiring cells to the lungs

• digested food and mineral ions absorbed from the small intestine and delivered to requiring cells around the body

• urea transported to the kidneys

• hormones released from the endocrine organs and delivered to target tissues/organs of the body

• heat energy transferred to cooler parts of the body/skin where heat is lost

what adaptions do red blood cells have and why are they important

• they are full of haemoglobin which binds to oxygen

• they have no nucleus to make more space for haemoglobin

• they have a biconcave disc shape to give them a large SA:V to maximize oxygen diffusion

what do white blood cells contain + do

• white blood cells are part of the body’s immune system

• they contain phagocytes and lymphocytes

what do phagocytes do

• they have a sensitive cell surface membrane that can detect chemicals produced by pathogenic cells

• once they encounter the pathogenic cell, they will engulf it and release digestive enzymes to digest it

what do lymphocytes do

• lymphocytes produce antibodies specific to the pathogen

• they also clone themselves to produce lots of lymphocytes that all produce the specific antibody required.

what are antibodies

• antibodies are proteins with a shape that is complementary to the antigens on the surface of the pathogen

• these antibodies enhance an immune response

what is the body’s response to infection

• the pathogen enters the blood stream and multiplies

• a release of toxins and infection of body cells causes symptoms

• phagocytes that encounter the pathogen recognize it as foreign and engulf and digest it

• eventually, the pathogen encounters a lymphocyte which recognises its antigens

• the lymphocyte starts to produce specific antibodies to combat that particular pathogen

• the lymphocyte also clones itself

• antibodies recognize and bind to the pathogens, marking them for destruction

• phagocytes engulf and digest the destroyed pathogens

how do vaccines work

• vaccines contain harmless versions of a pathogen

• when in the bloodstream, antigens within the vaccines trigger an immune response

• lymphocytes recognise the antigens in the bloodstream

• the activated lymphocytes produce antibodies specific to the antigen encountered

• memory cells are produced from the lymphocytes

• memory cells and antibodies subsequently remain circulating in the blood stream

how do vaccines induce long-term immunity

• memory cells lasting years are produced by the initial immune response

• further infection by the same pathogen will trigger an immune response that is much faster and larger compared

• due to the rapid nature of the response, the pathogen is unable to cause disease and the individual is said to be immune

what are platelets

• fragments of cells that are involved in blood clotting and forming scabs

• they help to prevent excessive blood loss and protect the wound from bacteria entering until new skin has formed

what happens when skin is broken

• platelets release chemicals which form an insoluble mesh across the wound

• red blood cells become trapped, forming a clot

• the clot eventually dries and develops into a scab

how does the heart function

• it is a double pump

• oxygenated blood from lungs enter the left side of the heart and it pumped to the rest of the body.

• deoxygenated blood from the body enters the right side of the heart and it pumped to the lungs

• blood is pumped towards the heart in veins

• blood is pumped away from the heart in arteries

what does the right/left atrium do

RIGHT: received deoxygenated blood from the body through the vena cava

LEFT: receives oxygenated blood from the lungs through the pulmonary vein

what does the right/left ventricle do

RIGHT: deoxygenated blood moves through and is pumped he lungs

LEFT: oxygenated blood moves through and is pumped to the rest of the body

why is the left ventricle thicker

• it needs more muscle because it has to pump blood around the whole body

• the blood in the left ventricle is higher pressure

• the right ventricle only pumps to the lungs and is lower pressure

what happens to the heart during exercise

• the heart pumps blood to respiring cells to supply oxygen and glucose and remove respiratory waste

• during exercise, muscle cells respire faster to increase energy supply

• the nervous system responds to this by transporting more amounts of oxygen and glucose using increased blood volume, more frequently with an increased heart rate

• at the end of exercise, the heart rate may remain high for a long period of time as oxygen is required to break down the lactic acid from anaerobic respiration

what do adrenaline levels do to the heart rate

• production of adrenaline increases heart rate as part of “fight or flight” response

what is coronary heart disease

when layers of plaque build up inside the coronary arteries from cholesterol. this blocks the coronary artery, resulting in a lack of oxygen for the heart muscle. this could lead to a heart attack

how does obesity increase the risk of coronary heart disease

• carrying extra weight can put a strain on the heart

• type 2 diabetes also further damages your blood vessels

• a poor diet high in cholesterol speeds up the build up of fatty plaques in the arteries leading to blockages

how does smoking increase the risk of coronary heart disease

• chemicals in smoke cause an increase in plaque build-up and blood pressure

• carbon monoxide also binds to haemoglobin, decreasing oxygen carrying capacity of red blood cells

how does high blood pressure increase the risk of coronary heart disease

• high blood pressure increases the force of the blood against the artery walls and consequently leads to damage of the vessels.

what are the types of blood vessels

• arteries (arterioles are smaller vessels which branch off from arteries)

• veins (venules are smaller vessels which branch into veins)

• capillaries

how are arteries adapted for their function

• arteries carry oxygenated blood at high pressure away from the heart quickly

• they have thick muscular walls containing elastic fibres to withstands and maintain the high pressure

• they have a narrow lumen which also helps to maintain high pressure

how are veins adapted for their function

• veins carry deoxygenated blood at low pressure towards the heart slowly

• they have thin walls and a large lumen which reduces resistance to blood flow under low pressure

• they contain valves to prevent the backflow of blood due to the low pressure

how are capillaries adapted for their function

• capillaries carry both oxygenated and deoxygenated blood at low pressure within tissues

• they have one cell thick walls for a short diffusion distance to allow for easy diffusion

• they have ‘leaky’ walls which allow blood plasma to leak out and form tissue fluid surrounding cells

what carries blood to/from the heart

• vena cava and pulmonary vein carry blood towards the heart

• aorta and pulmonary artery carry blood away from the heart

what carries blood to/from the lungs

• pulmonary artery carries blood towards the lungs

• pulmonary veins carry blood away from the lungs

what carries blood to/from the kidneys

• renal artery carries blood towards the kidneys

• renal vein carries blood away from the kidneys