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b8 (the heart, blood, living organisms obtain many of the substances they…
b8
the heart
the human heart is a double circulatory system
the natural resting heart rate is controlled by a group of cells in the right atrium also known as the pace maker
artificial electrical pace makers are used to correct any irregularities in the heart rate
the circulatory system is a system of blood vessels with a pump (the heart) and valves which prevent backflow
the heart has 4 chambers
left atrium
left ventricle
right atrium
right ventril
the right ventricle pumps blood to the lungs where gas exchange takes place
the left ventricle pumpsblood under high pressure around the rest of the body and back to the right side of the heart
coronary arteries supply a oxygen rich blood to the heart
heart valves in the heart prevent the blood backflow
some valves are faulty in people preventing the valve from opening properly or the heart valve might develop a leak because it doesnt close fully
in order to calculate how much blood is pumped every min by the heart the following equation is used
cardiac output = heart rate * stroke volume
cardiac output is the volume of blood pumped by a ventricle per minute
the units are
cm3min-1
stroke volume is the volume of blood pumped by ventricle per contraction
blood
red blood cells
other wise known as erythrocytes
have no nucleus so more room to carry o2
contain the red pigment haemoglobin which carries o2
they have a larger sa:v ratio for faster diffusion of oxygen
the 3 types of blood vessel
arteries
carry blood away from the heart
thick layers ofmuscle to withstand high level of prssure generated by the left ventricle
elastic tissue to stretch adn recoil as blood enters
small lumen which maintains pressure
all carry oxygenated blood except the pulmonary artery
veins
carry blood to the heart
thin walls
thin layers of muscle and elastic tissue
large lumen
valves to prevent backflow
carry blood under low pressure
all carry deox blood except the pulmonary vein
capillary
connect arteries and veins
site of exchange between blood and body tissues
once cell thick to enable rapid diffusion to occur
carries blood under low pressure and travels slowly maximising tbe time for exchange
white blood cells
an important part of the human immune system
one important type of wbc is lymphocytes which produce antibodies that are protients which bind to microbes and destroy them and anotehr type called phagocytes which surround and engulf foreign cells
plasma
plasma is the pale yellow fluid part of blood which transports cells, co2 hormones and waste
platelets
tiny fragments of cells with no nuclei that clump together to help form clots that protect the body by stopping bleeding
blood is a tissue consisting of plasma in which the red blood cells, white blood cells and platelets are suspended
living organisms obtain many of the substances they require for life by diffusion
for example ocygen minerals and dissolved food
they also get rid of waste products by diffusion for example urea and carbon dioxide
single celled organisms do not need transport systems to bring the minerals they need into their body or take waste away - they are able to recieve enough substances to their cells through diffusion alone due to a large sa volume ratio
larger multicelluar organisms need a mass tranposrt system because they have a relatively small surface area volume ratio
in humans the mass transport system is the blood and the gas exchange surface is the lungs
diffusion
factors which affect the rate of diffusion
the concentration gradient
the difference in concentration gradient between two areas next to eachother, particles will move down the concentration gradient from high to low, the larger the difference in concentration gradient, the faster the rate of diffusion
the surface area
larger surface area increases the rate of diffusion compared to volume ensures sufficient transport of organisms into and out of the cell - as sa increases the number of substances diffusing into the cell increases
the diffusion distance
smaller diffusion distance = faster rate of diffusion- respiroratory surfaces are usually only one cell thick for this reason
capillary walls are also once cell thick to make diffusion into and out of the blood faster
surface area volume ratio
the surface area volume ratio can be calculated by dividing an objects surface area by its volume
the lungs
adaptations for gas exchange - all gas exchange surfaces have features which increase the efficiency of gas exchange
these include:
large SA to allow faster diffusion of gases across the surface
thin walls to ensure diffusion distance stays short
good ventilation with air so that diffusion gradients can be maintained
good blood suply (dense cappilary network) to maintain high concentration gradient so that siffusion occurs faster
ts important to remember that gas exchange occurs through diffusion - breathing is essential in maintaining high concentration gradients between the air in the alveoli and the gases dissolved in the blood
in particular,, breathing keeps the oxygenlevel in the alveoli high and the carbon dioxide level low
what are alveoli
alveoli are tiny moist air sacs where gas exchange takes place
what are diaphgram
sheet of connective tissue and major muscle of respiration
adaptions of lungs
have alveoli increase the surface area
alveoli have a very good blood supply which maintains the concentration gradient
membranes of the alveoli are very thin to allow for a short diffusion distance
the heart pumps low oxygen/high co2 contaning blood to the lungs
in the lungs the co2 and oxygen are exchanged in the tiny air sacs called the alveoli at the end of the bronchial tubes
the alveoli are surrounded by capillaries
respiration
respiration is also sometimes called cellular respiration
this is because the reactions of respiration occurs inside cells
every living cell needs energy and this energy is released from glucose by a series of chemical reactions called respiration
respiration is an exothermic reaction
this means that the energy is transferred to the environmet
some of the energy is used inside cells for metabollic processes such as aerobic and anaerobic respiration
why do organims need energy
for movement - to enable mscle contraction in animals
to stay warm - to keep a steady body temperature in a cold environemnt
for chemical reactions - to build larger molecules from smaller ones
respiration can transfer energy in cells aerobically - with oxygen
the word equation for respiraion
glucose + oxygen - co2 + water
C6H12O6 + 6O2 6CO2 + 6H2O
aerobic respiration occurs inside mitochondria continuosly - gluclose is oxidised by oxygen to provide energy for the organism
aerobic respiration releases a large amount of energy from each glucose molecule
anaerobic respiration
respiration can transfer energy in cells anaerobically - meaning without oxygen
during hard excersise, muscle cells are respiring so hard that the body cannot provide enough oxygen to meet their needs
so the muscle cells switch to anaerobic respiration to transfer energy
glucose is not completely brken down to co2 and water so less energy is transferred,
an end product called lactic acid is formed
During exercise the human body reacts to the increased demand for energy. If insufficient oxygen is supplied to the muscle cells then anaerobic respiration occurs.
the heart rate increases to pump oxygenated blood faster through the muscle cells
breathing rate and breath volume increase, this increases the amount ofoxygen entering the blood stream
lactic acid is bilt up in the muscle cells during excerise
blood flows through the muscle cells and transports the lactic acid to the liver
the liver oxidises the lactic acid and converts it back to glucose
glucose is used in aerobic respiration or it is converted to glycogen and stores in the liver for later use
metabolism
organisms use the energy released by respiration for the continual enzyme controlled process of metabolism
metabolism is the sum of all reactions in the cell or the body
the conversion of glucose to starch is a metabolic reaction
gluscose and nitrate ions from the soil are used to synthesise protiens, these aremetabolic reactions
ficks law
ficks law is used to calculate the relative rate of diffusion across a membrane and it is represented by the equation
rate of diffusion = surface area* conc dif/ thickness of membrane
its proportional which means
the rate of diffusion will double if the sa or concentration difference is doubled