transport in animals Flashcards
what is a single circulatory system?
one around the body through the heart
what is a double circulatory system?
- blood travels twice through the heart for one circuit of the body
- overcomes the resistance of the systemic and pulmonary systems
what is a closed system?
transport medium in vessels doesn’t come into contact with cells
what is an open system?
transport medium is pumped directly into the body cavity
what are the differences between a complete and partial double system?
partial
- one ventricle and three chambers
- left and right side arent separated so oxygenated and deoxygenated blood can mix
complete
- blood passes twice through heart for one circuit
- has systemic and pulmonary system
why is a transport system required?
- SA:V ratio is too small so diffusion is too slow
- metabolic rate
- transport of waste or nutrients
what are the components of a mass transport system?
- pump
- circulating transport medium
- vessels
how does a fish circulatory system work?
- single circulatory system
- two heart chambers
- blood from body goes to atrium
- pumped from ventricle to gills to be reoxygenated
- metabolic capacity is low
how does an amphibian circulatory system work?
- three chambered heart
-2 atria 1 ventricle - atria receive blood from lungs and body
- blood can mix in ventricle
how does a reptile circulatory system work?
- three chambered heart
- ventricle is divided to stop blood mixing
- 2 main arteries for body and lungs
how does an insect circulatory system work?
- open system
- dorsal vessel is the main vessel
- tubular heart pumps haemolymph (blood)
- delivered to haemocoel (body)
- surrounds organs until it reenters heart via one way valves called ostia
- oxygen is delivered idrectly to the tissues
advs of single system
- less complex
- fewer major organs
disadvs of single system
- low blood pressure
- low metabolic rate
- slow blood flow
advs of double system
- pump blood further
- high blood pressure
- faster
disadvs of double system
- complex
role of elastic fibres in blood vessels
stretch and recoil so walls dont snap under the pressure
role of smooth muscle in blood vessels
contract and relax to change lumen shape and maintain pressure and pulse flow
what are the adaptations of arteries?
- thick walls to withstand pressure
- elastic fibres that can stretch and recoil to prevent snapping
- narrow lumen relative to wall thickness to maintain pressure
- collagen wall for strength
- endothelium lining to reduce friction
differences between arteries and arterioles
- arterioles have more muscle and less elastic fibre
- lower pressure but need to contract and relax more to maintain blood flow
- vasoconstriction and vasodilation to control capillary beds
what are the adaptations of capillaries?
very narrow diameter
- reduce blood flow to allow more time for gas exchange
thin walls of endothelium
- short diffusion pathway
leaky walls
- allows dissolved substances to leave the blood
what are the three types of capillaries?
- continuous
- fenestrated
- sinusoid
what does a continuous capillary do?
- limit the permeability of larger molecules
- eg. in the CNS blood-brain barrier
what does a fenestrated capillary do?
- allow for selective reabsorption
- eg in the kidneys
what does a sinusoid capillary do?
increases permeability of larger molecules eg. in the liver
what is pressure like at the arterial end of a capillary?
- hydrostatic pressure > oncotic/blood osmotic pressure
- hydrostatic pressure forces materials from the blood to the tissues
- oxygen and nutrients exit the blood
what is pressure like at the venous end of a capillary?
- hydrostatic pressure < oncotic/blood osmotic pressure
- materials move from tissues into blood
- waste is removed from tissues
what are the adaptations of veins?
- wide lumen to accommodate large volume of blood
- endothelium lining to reduce friction
- valves to prevent the backflow of blood
differences between veins and venules
- venules have no elastin fibres or smooth muscle
- several venules split from one vein
what is the composition of blood?
plasma (55%)
- hormones, waste, electrolytes
- proteins to maintain osmotic potential
erythrocytes (45%)
- transport oxygen via haemoglobin
buffy coat (>1%)
- white blood cells and platelets
where is tissue fluid found?
around cells
what is tissue fluid made from?
- substances that leak out of capillaries
- oxygen and waste
what is the effect of plasma proteins on oncotic pressure?
increases oncotic pressure and causes water to move into the blood vessels by osmosis
what is the role of the lymphatic system?
- aid immune response
- lipid transport
- maintaining blood pressure
how is lymph formed?
- large molecules that cant reenter capillaries enter the lymphatic system
- moves along larger vessels by muscle contractions and valves to prevent backflow
- returns to the blood where the subclavian veins meet the jugular veins
what are the lymph nodes?
- filter lymph
- produce antibodies to fight infection
what is the pericardium and what does it do?
- inelastic double walled sac
- created a closed chamber with subatmospheric pressure that aids atrial filling
- shields heart from friction
- barrier against infection
why is the left side of the heart thicker than the right?
- must pump further and overcome resistance of aorta and arterial systems of the whole body
- right only has to pump to lungs and overcome resistance of the pulmonary system
what is meant by cardiac muscles being myogenic?
involuntarily contracts
why do cardiac cells have more mitochondria?
more reliant on aerobic respiration
what are the three stages of the cardiac cycle?
- atrial sytole
- ventricular systole
- diastole
what happens in atrial systole?
- atria contracts
- ventricles relax
- blood moves from atria to ventricles
- atrioventricular valves open
- semilunar valves close
what happens in ventricular systole?
- atria relax
- ventricles contract
- blood moves from ventricles to body
- atrioventricular valves close
- semilunar valves open
what happens in diastole?
- all chambers relax
- blood returns to atria
- atrioventricular valves open
- semilunar valves close
what do valves do and how do they function?
- prevent the backflow of blood
- chordae tendinae prevent inverting
- high pressure infront closes them
- high pressure behind opens them
what is cooperative binding?
once one oxygen has associated, the structure of the haemoglobin changes making it easier for the rest to bind
what is the product of oxygen + haemoglobin?
oxyhaemoglobin
what are the three ways carbon dioxide can travel?
- diffusion directly into the blood plasma
- bind to haemoglobin
- move as hydrogen carbonate ions
how are hydrogen carbonate ions formed?
- carbon dioxide diffuses into the plasma and binds with water to form carbonic acid
- carbonic anhydrase in red blood cells causes it to become hydrogen carbonate and hydrogen ions
how does haemoglobin act as a buffer in CO2 transport?
when carbonic anhydrase catalyses the formation of HCO3 and H+, haemoglobin binds to the H+ so the pH isn’t altered and the carbon dioxide can be carried as HCO3
what is the chloride shift?
- when hydrogen carbonate ions leave the red blood cells, chloride ions must enter to prevent an electrical imbalance
- prevents erythrocytes from becoming positively charged
what is partial pressure?
- pressure exerted by oxygen within a mixture of gases
- a measure of oxygen concentration
what is meant by affinity for oxygen?
ease at which haemoglobin binds and dissociates from oxygen
what is a high affinity?
when oxygen binds easily and dissociates slowly
what is a low affinity?
- binds slowly
- dissociates easily
how is foetal haemoglobin different from adult and why?
has a higher oxygen affinity to allow binding while mothers haemoglobin is dissociating
why is a higher affinity essential for fetal survival?
- fetus gains oxygen from the mother across the placenta
- partial pressure of oxygen in the placenta is low
- while maternal haemoglobin is unloading fetal must be able to load
why is the oxygen dissociation graph a curve?
cooperative binding
why does myoglobin have a diferent curve?
one haem group so can only bind to one oxygen molecule so has a higher affinity
what is the bohr effect?
when partial pressure of carbon dioxide is high, haemoglobins affinity for oxygen decreases because CO2 lowers pH of the blood
why is the bohr effect important during exercise?
- more carbon dioxide so curve moves right
- at the same partial pressure of oxygen there is a lower % saturation of oxygen
- oxygen dissociates from Hb more readily
- oxygen used for aerobic respiration
what is the SAN?
sino-atrial node located in the upper wall of the right atrium
what is the AVN?
atrioventricular node connected to the Bundle of His
average bpm of pacemaker cells?
60/70bpm
why does the SAN not affect the ventricles?
layer of non conductive tissue stops the wave of depolarisation
why is there a delay at the AVN?
allows atria to empty and ventricles to fill
where does the contraction of the ventricles start and why?
at the apex to push blood up and out of the heart
what is the refractory period and why does it exist?
a period of insensitivity to stimulation to allow the heart to passively refill
describe atrial systole in the cardiac cycle
- SAN in the upper left wall of the right atrium sends a wave of depolarisation
- causes the cardiac muscle in the atrial walls to conract
- blood flows into the ventricles
describe ventricular systole in the cardiac cycle
- AVN picks up impulse and imposes a slight delay
- it sends its own wave of depolarisation down the Bundle of His and into the Purkyne fibres
- ventricle walls contract simultaneously at the apex
describe one cardiac cycle on an ecg
- p-wave
- PR interval
- QRS complex
- ST segment
- T-wave
what is a P-wave?
depolarisation of the atria in response to signalling from the SAN
what is the QRS complex?
depolarisation of the left ventricle triggered by AVN signalling
what is a T-wave
repolarisation of the ventricles
what are the PR interval and ST segment?
time for refilling before and after contractions
what does atrial fibrillation look like?
- irregular and rapid heart rate
- T and P wave are repeated multiple times before a QRS complex and there is no pause for refilling
what does ventricular fibrillation look like
- irregular ventricle contractions
- no t or p waves or refilling
what is the equation for cardiac output?
stroke volume x bpm
what process creates pressure inside the heart chambers?
isometric contractions
what is pressure like in:
- aorta
- tissue fluid
- lymph
- plasma
high
low
low
low
what is one advantage and disadvantage to erythrocytes lacking membrane bounds organelles?
- more room for haemoglobin which binds to oxygen
- wont survive long as they cant reproduce or repair themselves
why dont erythrocytes make use of the oxygen?
- no mitochondria so doesnt carry out aerobic respiration
- haemoglobin reversibly binds to the oxygen
why is oxygen not released until blood reaches capillaries?
arteries have thick walls so diffusion distance is too large
why does blood offload more oxygen to actively respiring tissues than resting tissues?
- higher carbon dioxide concentration in actively respiring tissues
- due to the bohr effect, haemoglobin has lower affinity for oxygen
what are the adaptations of erythrocytes?
- biconcave to increase surface area to volume ratio
- no nucleus to make room for more haemoglobin
- flexible to fit through capillaries
what is hydrostatic pressure?
force exerted by the fluid on the of the vessel
what is oncotic pressure?
force exerted by the proteins in the fluid
what are the layers of the artery walls from outside to inside
- tunica adventitia
- tunica media
- connective tissue (collagen+elastin)
- endothelium of tunica intima
what are three differences between blood and tissue fluid?
- blood has higher rbc count
- tissue fluid is lower pressure
- blood has higher O2 conc
suggest why blood and faeces have the highest concentrations of C-reactive protein and copeptin
- liver has a good blood supply
- substances released into bile
compare and contrast the circulatory systems of mammals and fish
similarities
- both have a closed system
- both have blood that flows in veins, capillaries and arteries
- both have a heart
differences
- single vs double system
- 2 chambers vs 4 chambers and a septum
- fish have a less effective system as they are cold blooded and metabolic demands are lower than mammals
suggest a mechanism by which carbon dioxide could reduce the affinity for oxygen of
haemocyanin
- carbon dioxide binds to water and forms carbonic acid
- dissociates into HCO3- and H+
- haemocyanin can act as a buffer for pH
explain why the visible blood vessels are likely to be veins
- larger lumen as carries mroe blood
- have thin walls so can bulge
- found closer to the surface of the skin
suggest why anabolic steroids are effective when applied to the surface of the skin
steroids are lipid soluble so diffuse through the phospholipid bilayer of skin cells into veins as they are closer to skin and provide a shorter diffusion pthway
suggest why reduced heart rate is sometimes seen in people who are very aerobically
fit
increased stroke volume due to increased thickness of cardiac muscle
explain why the oncotic pressure of the blood depends only on the concentration of
large plasma proteins
- large plasma proteins cannot pass through capillary but other solutes can
- imbalance of large plasma proteins between blood and tissue fluid results in oncotic pressure
