3.1.2 Flashcards
Why does a multicellular organism need a transport system whereas the unicellular organism does not?
Multicellular organism has a smaller SA:V ratio
multicellular organism has a higher metabolic rate
takes longer for oxygen to diffuse into the multicellular organism
longer diffusion distance
Why does a large multicellular animal like a mammal need a transport system?
small/ low SA:V ratio
diffusion is too slow / distance is too great
to supply enough oxygen
to prevent CO2 from building up
active
What type of circulatory system do animals have?
closed
double
circulatory system
How does the double circulatory system in an animal work?
Blood is carried in vessels and passes through the heart twice on each complete circuit of the body
What pressure does blood flow through the lungs?
lower
What pressure does blood return to the heart?
higher
How does a circulatory system work in fish?
blood passes through the heart once
Why is a circulatory system in fish slower than in mammals?
the pressure is lower
to avoid damage to gills
What are the differences between circulatory system in fish and mammals?
circulatory system in fish is slower and at a lower pressure
Fish have 1 atria and 1 ventricle , single
Mammals have 2 atria and 2 ventricle , double
circulatory system in mammals is faster and at a higher pressure
What circulatory system is found in fish?
closed circulatory system
single circulatory system
What circulatory system is found in animals?
closed circulatory system
double circulatory system
What circulatory system does an insect have?
open
How does the open ciculatory system work in mammals?
fluid circulates through the body cavity so tissues and cells are in direct contact with blood
What helps circulate blood in insects?
movement
What is a closed circulatory system?
blood is maintained within vessels
What is a single circulatory system?
blood passes through the heart once for each circulation
What is a benefit of having a double circulatory system?
blood can go to the lungs at a lower pressure
rather than a higher pressure
as a higher pressure would damage the lungs
blood can also be under higher pressure so that it can reach far away parts of the body
Why can’t the blood in a fish be under high pressure?
the gills would be damaged
How does the type of circulatory system limit the size of an organism?
double circulatory system
allows all cells to receive oxygen and for all body parts to receive blood and nutrients are received and glucose a lot quicker
single circulatory system will not receive these nutrients as quickly
What is an open circulatory system?>
blood is not always held in vessels
fluid circulates through the body cavity so tissue s and cells o the animals are in direct contact with blood
How does fluid move in a closed circulatory system?
tissue fluid bathes the tissues and cells delivering essential nutrients
this allows for the heart to pump blood at a high pressure
What does blood moving at a higher pressure allow?
faster delivery of oxygen and nutrients
faster removal of waste products and carbon dioxide
What are the 3 main types of blood vessel?
artery
capillary
vein
What do arteries do?
carry blood away from the heart and into the arterioles
How much pressure are the arteries under when carrying blood away from the heart and into arterioles?
high pressure
Where is the high blood pressure that arteries have blood flow under generatied?
contraction of the ventricles
What 2 vessels do capillaries link?
arterioles to veins
What do capillaries do?
allow the exchange of carbon dioxide and oxygen between tissues and blood
What do veins do?
carry blood from capillaries back to the heart
What do venules do?
links capillaries to veins
What does having a collagen layer allow for a vessel?
provides strength to the vessel
What does a layer of smooth muscle and elastic tissue allow for a vessel?
smooth muscle - contracts to control the flow of blood
Elastic tissue - stretches and recoils to original shape to maintain the blood pressure
What does squamous epithelium allow for a vessel?
smooth
reduces friction between blood and the walls of the vessel
What is the lumen?
area where blood passes through
What is an artery composed of?
thick layer of elastic fibres
smooth muscle
narrow lumen
thin layer of collagen
What generates the high blood pressure in the arteries?
the contraction of the ventricles
What does the thick layer of elastic fibres in the arteries allow?
vessel can stretch and recoil to original shape
maintian blood pressure
What does the layer of smooth muscle allow for the artery?
contracts to control blood flow
What does the collagen layer allow in the artery?
strength
What is the structure of an arteriole?
thicker muscle layer than artery
thin elastic layer
thick layer of muscle
narrow lumen
What does the layer of muscle being thick compared to an artery allow for the arteriole
Muscle can contract - vasoconstriction
narrows lumen
also allows vasodilation
allows blood flow into capillaries to be controlled
Why is the elastic layer thinner in an arteriole compared to ana rtery?
blood pressure is lower
What is the structure of a capillary?
smooth epithelilal cells
lumen
What is the structure of an arteriole?
thick muscle layer compared to artery
thin elastic layer
thick layer of muscle
Why is the muscle layer thicker in an arteriole?
vasocnonstriction to narrow the lumen
vasodilation
What does vasocnostriction allow?
allows blood flow into the capillary to be controlled
Why is an the elastic layer thinner in the arteriole?
blood pressure is lower
What is the structure of a capillary?
smooth epithelium cells
What does being made of squamous epithelium cells allow?
smooth
so prevents friction between blood and capillary wall
How is being one cell thick good for the capillary?
short diffusion distances between capillaries and tissues
so speeedier exchange of substances
What does the small gaps / fenestrations between epithelila cells allow?
allows passage of tissue fluid in and out of the capillary
What does lots of / network capillaries allow?
gives a large SA for the exchange of substances like CO2 and O2 in and out the tissue fluid
Why does the blood pressure drop in the capillaries ?
large surface area of capillaries
How is being narrow a n advantageous feature of a capillary?
RBC HAVE TO SQUEEZE THOUGH REDUICNG DIFFUSION DISTANCE
ALLOWS FLOW OF BLOOD AND LLOWS MORE EXCHANGE OF SUBTSTABCES
wHAT is the structure of a vein?
large lumen
thin elastic fibre and smooth muscle
collagen layer
valves
How does having a large lumen help the vein carry out it’s function?
reduces friction
and helps increase the speed of blood flow
What does having smooth endotherlium in the vein allow?
reduces friction
Why is there athin layer of elastic tissue in the bein?
under lower pressure
Why is the layer of collagen thin?
provides strength
Why are there valves in the vein?
to prevent the backflow of blood
Where does tissue fluid form?
capillaries
Which end of the capillary is under higher pressure?
blood at the arteriole end
Outline the process of the formation of tissue fluid?
1) Blood at the arteriole end of the capillary is under a higher hydrostatic pressure than at the venuole end
2) Water and dissolved amino acids are forced out of the capillaries through fewest rations
4) Large proteins and RBC remain in the capillaries reducing the W.P
5) The oncotic pressure is higher than the hydrostatic pressure at the venuole end
6) Some tissue fluid re-enters the capillary and the rest enters the lymphatic system
What remains in the capillaries after tissue fluid is forced out through fenestrations?
Large proteins
RBC
What effect do large proteins and RBC have on tissue fluid water potential?
reducing
What is forced out through fenestrations?
water and dissolved amino acids
What are the pressures of the oncotic pressure like at the venuous end?
Oncotic Pressure is higher
Where does some of the tissue fluid enter?
lynphatic systemn
What components are present in blood?
RBC
WBC
Platelets
Proteins
Water
Dissolved solutes
What are the components of tissue fluid?
Water
Dissolved solutes
Very few proteins
What would the tissue fluid of an infected person also contain?
WBC
What does tissue fluid not contain?
RBC
Platelets
What does lymph contain?
WBC
Water
Dissolved solutes
Antibodies are the only proteins
What does lymph not contain>
RBC
Platelets
What is the tricuspid valve known as?
right atrioventricular valve
What does the semi-lunar valve do?
stops blood leaving the ventricle
What does the pulmonary artery do?
Takes deoxygenated blood to the lungs
What does the septum do?
separate 2 sides of the heart
Why are semilunar valves important?
prevents backflow from the arteries back into the ventricles
What is the role of the coronary arteries?
to supply blood to the heart muscle
What does the coronary arteries supplying the heart muscle with blood allow?
allows heart muscle to do aerobic respiration so muscles can contract to pump heart muscle
What is the cardiac cycle?
sequence of contraction
and relaxation
of the heart chambers
during 1 heartbeat
When do both sides of the heart contract?
at the same time
What is systole?
when heart muscle is contracting
What is diastole?
when heart muscle is relaxed
What happens during diastole?
In veins:
Pressure is higher in the veins than in the atria
beacuse atrial muscles are relaxing
atria inc in volume
pressure falls
Blood enters atria
inc pressure
pressure is now higher in atria than ventricles
Blood moves from atria to ventricles by pushing open atrioventricular valves
In diastole, what happens when the atria inc in volume?
pressure drops
In diastole, Why is pressure higher in the veins than in the atria?
atrial muscles are relaxing so atria increases in volume and pressure falls
Why is pressure higher in the atria than in the ventricles in atrial systole?
blood has entered atria and increased pressure
How does blood move from the atria to the ventricles ?
by pushing open the atrio-ventricular valves
What happens in atrial systole?
atria contract
dec volume
inc pressure
any remaining blood is forced from atria into ventricles
What haooens when atria contract?
causes a further decrease in volume
What does a further decrease in volume cause in atrial systole?
inc in pressure
What happens to any remaining blood in the atria?
forced out from the atria into the ventricles
What happens in ventricular systole?
ventricle volume decreases
as blood fills them
inc in pressure
ventricle walls contract
atrioventricular valves shut
semi-lunar valves open
blood enters arteries
until pressure of arteries is lower than the pressure of the ventricles blood falls back and semi-lunar valves shut
Why does the volume of the ventricles decrease at the beginning of the ventricular systole>?
blood fills them
What valves shut in ventricular systole?
atrioventricular
What valves open in the beginning of ventricular systole?
semilunar
What is the pressure like in the atria during ventricular systole?
Low pressure
What are the 3 parts of the cardiac cycle?
atrial systole
ventricular systole
diastole
What do cells in the right atrium aact as?
pacemakers
What are the cells in the right atrium that act as pacemakerscalled?
SAN
What does the SAN do?
these cells initiate a nerve impulse without simulation from the nervous system
What does SAN do to the atria?
send nerve impulses through the atria
What happens to the atria when they recieve a nerve impulse?
atria contract simultaneously = atrial systole
What recieves the wave of excitation and then introduces a delay?
AVN
Why does the AVN introduce a delay?
so that the ventricles contract after the atria
we need time for the atria to empty blood and force blood into the ventricles
What would happen if there was no delay at the AVN?
there would be no time for the atria to empt and force blood into the ventricles
pumping of blood around the heart would not be efficient
What happens after the short delay at the AVN?
wave of excitation spreads down
bundle of His
into the purkyne fibres
ventricles contract from the apex upwards
What happens when the wave f excitation spreads down the bundle of his and into the purkyne fibres?
ventricles contract
What is good about the wave of excitation at the apex upwards?
forces blood from the bottom of the ventricles
up through the open semi-lunar valves
into the arteries
that take blood way from the heart
ventricular systole
Is there a wave of excitation during diastole?
no
How is heart action initiates and coordinated?
SAN initiates excitation
a wave of excitation spreads over atrial wall
atria contract in atrial systole
contraction is synchronised
delay at AVN
excitation spreads down SEPTUM
and down the bundle of His and down the purkyne fibres
ventricles contract in ventricular systole from the apex
What indicates ventricular fibrillation in an ECG diagram?
lots of QRS
What indicates atrial fibrillation in an ECG diagram?
undistinctive P wave
How does a normal heartbeat compare to a slow heart beat?
slow heartbeat has fewer QRS’s
longer time between t wave of 1 heart beat and t wave of the next
still have same amplitude
What is oxygen bound to in Hb?
Haem groups
Hb + 4O2 =
Hbo8
oxyhaemoglobin
What is the partial pressure of oxygen?
measure of oxygen concentration
What does a greater partial pressure of oxygen mean?
higher concentration of oxygen
What happens when the first oxygen binds to the Hb?
changes the shaoe of the Hb slightly making it easier for 2 more O2 to bind
Why does the oxygen disassassociation curve not reach 100% saturation?
it is hard for the 4th Oxygen to bind to the heamoglobin
Where is 5% of CO2 transported to?
dissolved in plasmaW
hat happens to 10% of CO2 being transported?
combines with Hb
to form carbainohaemoglobin
What happens to 85% od CO2 being transported?
HCO3-
How are hydrogencarbonate ions formed?
CO2 diffuses into blood
some enters the RBC
where it combines with water to make carbonic acid
carbonic anhydrase releases H+ and HCO3-
Cl- move into RBC to maintain charge of RBC - CL- shift
hydrogen ions in RBC are taken up by the Hb which acts as a buffer maintaining pH
WWhat happens when cARBON DIOXIDE diffuses into the blood?
some co2 enters the rbc
What happens when some co2 combines with water?
carbonic acid is formed
What enzyme catalyses water and carbonic acid formation?
carbonic anhydrase
What did the reaction that forms carbonic acid release?
hydrogen ions
hydrocarbonate ions
What happens to HCO3- in the RBC?
diffuse out RBC
What do Chloride ions do?
move into RBC
Why do Cl- move into RBC?
to maintain the charge of the RBC
What is the chloride shift?
chloride ions move into the RBC to maintain the charge of the RBC
What happens to the hydrogen ions in the RBC?
H+ taken up by Hb which acts as a buffer
How are HCO3- formed?
CO2 diffuses into blood
some CO2 enters RBC
that CO2 combines with water -> carbonic acid
catalysed by carbonic anhydrase
H+ rel;eased
HCO3- released
Cl- move into RBC
to maintain the charge of the RBC - CL- shift
H+ in RBC taken up by Hb
acts as a buffer
maintains pH
What happens at high concentrations of CO2?
the shape of the Hb is altered
Hb’s affinity for oxygen reduced
more dissociation of oxyhaemoglobin
so more oxygen is available for respiring tissues
Hb acts as a buffer
by binding to the hydrogen ions forming haemoglobinic acid
Hb binds to the CO2 forming
carbaminohaemoglobin
What happens to Hb when there are high concetrations of CO2?
Shape is altered
What happens to Hb affinity for oxygen at high concentrations of CO2?
Reduced affinity
What haooens to oxyhaemoglobin at higher concetrations of CO2?
more dissaociation of oxyhaemglobin
so more oxygen available for respiring tissues
What does Hb act as ?
a buffer
How does Hb act a s a bugffer?
Hb binds to the hydrogen ions forming
haemoglobinic acid
What happens when Hb binds to CO2?
carbaminohaemoglobin
What affinity for oxygen does fetal Hb have?
higher
Where does fetal Hb take up oxygen?
at a lower partial pressure
What pressure of oxygen does the placenta have?
lower partial pressure
When will the adult Hb dissociate?
at lower partial pressure
What is the lower partial pressure of oxygen loacted in?
human muscle capillaries
What is the higher partial pressure of oxygen located in?
human lung alveoli
