3.2 transport in animals Flashcards
double circulatory system
blood flows through the heart twice on each complete circuit of the body
single circulatory system
blood flows through the heart once for each circuit of the body
need for a transport system in large animals
- all animals need oxygen + nutrients to grow and survive
- need to remove waste products so they dont build up and become toxic
- large animals mean diffusion distance is too long, and not efficient enough to supply all the requirements
3 factors that influence the need for a transport system
- size
- SA:V
- level of metabolic activity
how does size affect need for a transport system
- cells inside a LARGER organism are further from surface
- greater diffusion distance
- diffusion too slow to supply all requirements
- ALSO, outer cells use up supplies so less reaches the cells deep inside
how does SA:V affect need for a transport system
- small animals = LARGE sa:V
-for each unit3 of tissue in their body they have a sufficient area through which exchange can occur
how does level of metabolic activity affect need for a transport system
- animals need energy to move, which requires oxygen for aerobic respiration
- animals that keep themselves warm (eg mammals) need even more energy
3 features of a good transport system (humans)
- effective fluid or medium to carry nutrients, oxygen and waste around the body (blood)
- a pump to create pressure to push the fluid around the body (heart)
- exchange surfaces to allow substances to enter the blood and leave where needed (capillaries)
fish type of circulatory system
single
mammals type of circulatory system
double - 2 separate circuits
pulmonary circulation
circuit that carries blood to longs to be oxygenated
systemic circulation
circuit that carries the oxygen and nutrients around the body to the tissues
single circulatory of fish disadvantages
- blood pressure drops as blood passes through capillaries of the gills
- blood has a low pressure as it flows towards the body, so flows slowly
- limited rate at which oxygen and nutrients are delivered to respiring tissues and co2 and urea are removes
why is it not a problem that fish circulatory system is only single and bad
- fish are less metabolically active than mammals as dont maintain body temperature
- so need less energy
-single circulatory delivers sufficient oxygen and nutrients for their needs
of the 2 circulatory systems WITHIN double, which carries blood at a higher pressure
systemic (oxygenated blood to respiring tissues)
why must pressure be lower in pulmonary circulation
to not damage the delicate lung capillaries
arteries
carry blood away from heart
arterioles
small blood vessels, distribute blood from an artery to the capillaries
closed circulatory system
blood held in vessels
open circulatory system
blood not held in vessels
disadvantage of open circulatory system
- bp low so slow blood flow
- circulation of blood affected by (or lack of ) body movements
- slower delivery of o2 and nutrients
- slower removal of co2 and other wastes
what bathes tissues and cells in OPEN circulatory
blood
what bathes the cells in CLOSED circulatory
tissue fluis
advantages of closed circulatory system
- higher bp, so quicker blood flow
- more rapid delivery of oxygen and nutrients
- more rapid removal of CO2 and other wastes
- transport independent of body movements
what do all blood vessels have
endothelium
endothelium
- thin inner lining layer
- smooth to reduce friction with the blood
why is the artery wall thick
to withstand high pressure
artery lumen? (2)
- small to maintain high pressure
- inner wall folded to allow lumen to expand as blood flow increases
three layers of wall
innermost to outermost
- tunica intima
- tunica media
- tunica adventitia
tunica intima
- endothelium
- elastic tissue
tunica media
- smooth muscle + elastic tissue
tunica adventitia
- collagen
-elastic tissue
purpose of elastic tissue
stretch and recoil to withstand blood pressure, and MAINTAIN
purpose of smooth muscle
- strengthen walls to waistband pressure
- contract and narrow lumen to reduce blood flow
purpose of collagen
protects blood vessels from damage by over stretching
why do arteries near the heart have more elastic tissue
- stretch and recoil
- evens out fluctuations in blood pressure created by the heart
arteriole walls contain
smooth muscle
why is it important arterioles have smooth muscle
- can contract to constrict diameter of lumen
- increases resistance to flow and reduces rate of blood flow
- can divert the flow of blood to regions of the body that demand more oxygen
capillary lumen
- very narrow
- diameter of red blood cell
- RBCs squeeze through as they pass along, helping the transfer of o2
capillary walls (2)
- single layer of flattened endothelial cells -> short diffusion distance for materials being exhcanged
- leaky walls -> allows plasma and dissolved substances to leave the blood
venules
connect capillary to vein
vein lumen
large
- low pressure blood, reduces friction
vein walls (2)
- less thick
- thinner collagen, elastic tissue and smooth muscle as dont need to stretch and recoil as low pressure
veins contain …
Valves
purpose of valves
prevent back flow of blood
how is some blood in the veins moved
- thin walls mean contraction of surrounding skeletal muscle flattens vein
- pressure applied to blood, forcing it to move along
hydrostatic pressure
exerted by a fluid when pushing against the sides of a vessel
lymph
fluid in lymphatic system
oncotic pressure
pressure created by osmotic effects of solutes
blood contains
PLASMA
What does blood plasma contain (7)
dissolved substances
- o2 + co2
- glucose
- amino acids
- hormones
- platelets
-RBCs
where is blood
contained in vessels (closed circulatory )
difference in tissue fluid v blood plasma
- tissue fluid doesnt contain cells or plasma proteins
how is tissue fluid formed
- blood flowing to tissues is in the CAPILLARIES
- at the arterial end of the capillary, the blood has a high hydrostatic pressure. the pressure pushes the blood fluid out of the capillaries through the capillary wall.
- the fluid that leaves consists of plasma with dissolved nutrients and oxygen (tissue fluid)
- RBC,WBC, Platelets are all too large to be pushed out of the small gaps in the capillary wall
how does tissue fluid re enter blood
- bp at VENOUS end of capillary is lower
- some tissue fluid returns to the capillary carrying co2 and other waste into the blood
does all tissue fluid return to the blood?
NO
Some is directed to the lymphatic system, which drains excess tissue fluid out of the tissues and returns it to the blood via the subclavian vein in the chest
fluid in the lymphatic system
lymph (similar to tissue fluid with more lymphocytes)
how do lymph nodes become swollen
- tissue is infected -> capillaries more leaky -> more fluid directed into the lymph system
compare the pressures in blood plasma, tissue fluid and lymph
blood plasma: - high hydrostatic, more negative oncotic
tissue fluid: - low hydrostatic, less negative oncotic
lymph: - low hydrostatic, less negative oncotic
hydrostatic pressure of blood…
pushes fluid out into the tissues
hydrostatic pressure of tissue fluid…
pushes fluid into capillaries
oncotic pressure is always
negative
oncotic pressure of blood…
pulls water back into blood
result of all the forces
creates a pressure gradient
- fluid pushed out of capillary at arterial end
- fluid pushed into capillary at venule end
right side of heart
pushes deox blood to the lungs to be oxygenated
left side of heart
pumps ox blood to the rest of the body
coronary arteries
- surface of heart
- supply oxygenated blood to the heart muscle
atria
upper chambers
ventricles
lower chambers
Right side of heart blood flow
- deox blood
- enters heart through vena cava
- into right atrium
- through AV valve
- to right ventricle
- leaves throguh SL valve to pulmonary artery to lungs
- where it is oxygenated
left side of heart blood flow
- ox blood from lungs
- enters through pulmonary vein
- into left atrium
- through AV valve into ventricle
- leaves through aorta
- to rest of body
septum
- wall of muscle separating the ventricles
- ensures ox and deox are kept separate
where are the semilunar valves
at the base of the major arteries where they exit the heart
- prevent back flow when the ventricles relax
why are atrial walls thin
- chambers dont need to create much pressure
- push blood a short distance down to the ventricle
right ventricle walls
- thicker than atrium
- less thick than left ventricle
- not as high a pressure needed as blood goes a shorter distance to the lungs
- alveoli are delicate and could be damages by high bp
atrial systole
- left and right atria contract together
- small increase of pressure
ventricular systole
- left and right ventricles contract
where does contraction start
the base(apex) of the heart so blood is pushed up towards the base of the arteries and pushed out through there
diastole
- muscular walls of all chambers relax
- elastic recoil allows an increase of volume so blood can flow in
affinity
strong attraction
dissociation
releasing the oxygen from the oxyhaemoglobin
haemoglobin + oxygen ->
oxyhaemoglobin
when does association of oxygen and haemoglobin occur
in the lungs
- where pO2 is high
when does dissociation of oxygen and haemoglobin occur
in the tissues
- where pO2 is low
veins have little
elastic fibre or smooth muscle
what is pO2
- partial pressure of oxygen
- amount of o2 dissolved in the blood
transport of oxygen
- oxygen absorbed in blood from alveoli in lungs
- o2 molecules enter blood plasma
- become associated with the haemoglobin inside the erythrocytes
- takes o2 molecules out of solution so maintains a steep concentration gradient, allowing more o2 to enter the blood from the lungs
- blood carried to body tissues
-o2 dissociates to release the oxygen for aerobic respiration
units of partial pressure
kPa
cardiac output =
heart rate * stroke volume
tachycardia
-heart beats too fast
-heart rate over 100 bpm
- qrs peaks too close together
bradycardia
- heart beats too slow
- heart rate below 60bpm
- lots of athletes have as fit so cardiac muscle contracts harder so fewer contractions required
- qrs far apart
fibrillation
-irregular heartbeat disturbing the rhythm
ectopic heartbeat
- heart beats too early, followed by a pause
- larger qrs too soon
P wave
atrial systole
QRS complex
ventricular systole
T wave
ventricular diastole
how do ECG’s work
- monitor electrical activity of heart
- electrodes placed on skin
- produce an ECG
red blood cells are known as
erythrocytes
what happens after the first o2 molecule binds to haemoglobin
CONFIRMATIONAL CHANGE
- allows the next one to bind easier, known as cooperative binding
3 ways co2 is transported around the body
- directly in the plasma
- bindsto haemoglobin, forming carbaminohaemoglobin
- MOST in HCO3- ions
how are hydrogen carbonate ions formed
- CO2 diffuses from plasma into RBC’s
- inside, co2 + h20 -> H2CO3 (carbonic acid)
- catalysed by carbonic anhydrase enzyme found in RBC’s
- H2CO3 dissociates into HCO3- and H+ ions
- haemoglobin acts as a BUFFER -> it combines with h+ ions to form haemoglobinic acid so prevents them from lowering the pH in the cell
- the HCO3- ions diffuse out of the RBC into the blood plasma
why does H2CO3 take longer to form in plasma than in RBC’s
plasma doesnt contain the carbonic anhydrase enzyme which catalyses the reaction
Chloride shift
- after the HCO3- ions are transported out of the RBC’s by a transport protein
- to prevent an electrical imbalance, negatively charged Cl- ions are transported into the RBC’s by the same transport protein
what would happen without the chloride shift
RBC’s would be positively charged due to a buildup of h+ ions formed from the dissociation of H2CO3
when is haemoglobin staurated
all oxygen binding sites are taken up with oxygen
- contains 4 O2 molecules
when haemoglobin has a high affinity…
it binds easily and dissociates slowly
when haemoglobin has a low affinity…
it binds slowly and dissociates easily
where in the body is po2 low (bottom left of graph)
respiring cells
explain the sigmoidal haemoglobin curve
- very shallow bottom left- is difficult for the first o2 molecule to bind
- conformational change- is easier for the second and third molecule to bind
- molecule approaches saturation, so takes longer for the 4th o2 molecule to bind
where is po2 high (top right of graph)
lungs
foetal haemoglobin has
a higher a affinity for oxygen than adult haemoglobin
why does foetal haemoglobin have a higher affinity
- po2 oxygen low in placenta
- mothers haemoglobin dissociates at these lower po2
- but fetal has a higher affinity so takes UP oxygen at lower po2
curve for foetal haemoglobin
is to the left of adult
at any given po2, foetal haemoglobin has a higher percentage saturation than adult
why is it important that after birth babies begin to produce adult haemoglobin
- easy release of o2 in the respiring tissues for a more metabolically active individual
curve furthest to the left means
haemoglobin with the HIGHEST affinity for oxygen
po2 at lower altitudes
lower
the Bohr effect on the curve
down to the right
what is the Bohr effect
- effect of increasing CO2 on haemoglobin
- haemoglobin cant hold as much oxygen, so oxygen released to tissues
-overall, when more co2 is present, haemoglobin is less saturated with o2 - it means that when there is more co2 (because of increased respiration) more o2 is released, which is what the muscles need
invertebrate circulatory system
- heart is segmented. the blood is pumped, starting from the back into a single main artery
- the artery opens up into the body cavity
- the blood bathes the insect’s organs, gradually making its way back into the heart segments through valves
which of the 3 fluids contains RBCs
blood only
they are too big to fit through the capillary walls
which of the 3 fluids contain WBCs
all three
- most nbc’s are in the lymph, and are only in tissue fluid when there an INFECTION
which of the 3 fluids contains platelets
ONLY blood (too big to fit through capillary walls)
which of the 3 fluids contains proteins
mostly blood (the rest are too big)
lymph only has antibodies
which of the 3 fluids contains water
all three
WP of blood lower than the other 2
when the pressure is greater BEHIND a valve…
its forced open
when the pressure is greater IN FRONT of a valve
its forced shut
myogenic
contracts and relaxes without receiving signals from the nerves
electrical pathway
- SAN (pacemaker) sets the rhythm of the heartbeat by sending wave of excitation to atrial wall
- the right and left atria contract at the same time (atrial systole)
-the nonconducting collagen tissue at the base of the atria cant conduct the wave of excitation. So the only route for the wave is to the AVN - AVN delays the wave
- wave spreads down septum, then bundle of His to the purkyne tissue, which carries the wave of excitation to the walls of the left and right ventricles, which contract simultaneously from the bottom (APEX) up
where is the SAN
wall of the right atrium- near the vena cava entrance
Where is the AVN
top of the septum
what does the AVN do
- delays the wave of excitation to allow the atria to finish contracting and for the blood to flow down into the ventricles before they contract
- sends impulse to septum (bundle of his)
how is hydrostatic pressure created in the heart (1)
contraction of VENTRICLE
why does hydrostatic pressure decrease as blood moves away from the heart
- divides into more smaller vessels
- have a larger cross sectional area
- reduced resistance to blood flow
3 reasons for large organisms needing system
- small SA:V
- large (diffusion pathway too long so too slow to supply enough oxygen and prevent CO2 building up)
- high metabolic rate (v active)
ECG is
electrocardiogram
SAN
Sino-atrial node
AVN
atrio-ventricular node
need for the delay at the AVN (3)
- atria fully contract
- ventricles fill
- so ventricles dont contract too early
why do the purkyne fibres spread wave of excitation to the APEX of the ventricles (3)
- systole starts at the bottom
- so blood is pushed upwards into the arteries
- ventricles are fully emptied
explain the fluctuation in the pressure in the aorta
- systole of left ventricle increases pressure
- diastole decreases pressure
number of fluctuations in aorta per minute is
HEART RATE
Why MUST blood pressure be Lowe run the capillaries
- walls only one cell thick
- would burst
does tissue fluid contain neutrophils
yes
advantage of blood in vessels
- higher BP
- higher rate of flow
- flow can be directed
withstanding pressure in the arteries (2)
- thick walls, collagen, strong
- folded endothelium, no damage to wall
maintaining pressure in the arteries (2)
- elastic fibres -> recoil
- smooth muscle -> NARROWS lumen
WHY DOES The left ventricle have more muscle than left atrium
- more force
- higher pressure
- BLOOD PUSHED AGAINST GREATER FRICTION
- blood pumped a further distance
what does every efficient circulatory system contain (+ parallels to mammals)
pump - heart
means of maintaining pressure - artery
transport medium - blood
exchange surface - capillaries
Bohr shift moves
to the RIGHT- affinity for o2 decreases
biggest diff in skeletal and cardiac muscle
- cardiac is myogenic
- cardiac doesnt fatigue
when talking about wall thickness and blood reference …
- force
- pressure
- distance of blood flow
3 stages of cardiac cycle
- atrial systole
- ventricular systole
- (a then v) diastole
describe diastole
-atria and ventricles relaxed
- blood enters atria via vena cava and pulmonary vein
- pressure of the blood increases within the atria
describe atrial systole
- atrial muscle walls contract, increasing the pressure further
- AV Valves opem, bloof flows to ventricles
-ventircles are still relaxed at this point
describe ventricular systole
- after delay due to AVN, ventricle walls contract, increasing the pressure MORE than the atria
- AV valves close, semilunar valves open
- blood pushed out of ventricles into pulmonary artery and aorta
stroke volume
vol of blood that leaves the heart at each. beat
cardiac output defintion
vol of blood leaving one ventricle in one minute
dissociation curve labels
x = po2
y = saturation of haemoglobin with oxygen
eg high po2
alveoli (lungs)
eg low po2
respiring tissues
decreased affinity = (in terms of loading)
MORE oxygen is unloaded
high metabolism animals haemoglobin curve
to the RIGHT
- lower affinity
- higher metabolic rate, so more oxygen unloaded to provide energy for respiring muscles
describe how dissolved substances enter tissue fluid from the capillaries
- diffusion of substances
- down conc grad
- higher hydrostatic pressure in capillary
- walls of capillary leaky and has fenestrations
- fluid forced out of capillary
- small molecules leave WITH it
need for coordination (SAN etc)
- cardiac muscle myogenic; can contract and relax rhythmically even without connection to body
- BUT atrial muscle has a higher frequency of contraction compared to ventricular
- could cause inefficient pumping so therefore needs to be synchronised
why do RBC’s not use the oxygen they transport (3)
- oxygen bound to haemoglobin while transported so cant be used
- lack mitochondria
-so cant use it for aerobic respiration
what prevents inversion of the valves after they are shut
chordae tendinae
3 diff between artery and vein
ARTETY:
- no valves
- folded endothelium
- thicker smooth muscle + elastic fibres
- less collagen
oncotic pressure in capillary…
doesn’t change
SEMILUNAR VALVES ON GRAPH
top 2
open -> closed
pressure in lymph and tissue fluid is
low
describe the role of heamoglobin (4)
- high affinity for o2
- o2 binds to haemoglobin in areas of high po2
- to form oxyhaemoglobin
- oxygen is released where po2 is low
Bohr shift
- H+ ions react with haemoglobin (haemoglobinic acid)
- altering its tertairy strucutre
- reduces affintiy of Hb for oxygen
- so more o2 released where co2 concnetratin high
why do veins have more collagen than arteries
to give structural support as they carry larger volumes of blood
