Flashcards in Animal Transport Deck (131):
Why is membrane diffusion too slow to satisfy needs in multicellular (4)?
•High metabolic rate.
•Some cells deep within body = long diff pathway.
•Tough outer surface so gases can't diffuse through their skin.
What is mass flow?
Bulk movement of blood in a specialised transport system to carry materials from organisms' specialised exchange organs to body cells.
3 features of every mass flow system:-
•Suitable medium to carry materials (blood).
•A pump (e.g. heart) for moving blood within the vessels.
•Valves to maintain flow in one direction.
2 things some MF systems also have:-
•Respiratory pigment e.g haemoglobin which increases transportable O volume.
•vessel system that forms a branching network to distribute blood to all parts of the body.
What occurs in an open circulatory system?
Blood doesn't flow through blood vessels, but instead bathes the tissues directly whilst held in a cavity called the haemocoel.
Open system process in insects (4):-
-long dorsal (top) tube shaped heart runs the body length.
-blood pumped out at low pressure into haemocoel.
-materials directly exchanged between blood + cells.
-blood returns to heart slowly.
Why is no respiratory pigment needed in insects?
O2 diffuses directly to the tissues from trachea so blood doesn't transport O2/CO2.
Blood moves in vessels. Two types, single circulation (blood passes through heart once) and double circulation (twice).
Single circulation system in a fish (4):-
•ventricle of heart pumps deoxygenated blood to gills where its pressure falls.
•oxygenated carried to the tissues.
•from there, deox returns to the atrium of the heart.
• blood moves to ventricles, circulation starts again.
What colours represent deoxygenated and oxygenated blood?
Blue = deoxygenated.
Red = oxygenated.
Single closed circulation in earthworms (3):-
•Closed, even though though a relatively simple organism.
•blood moves forward in a dorsal vessel and back in a ventral vessel.
• blood moves through the vessels by the the pumping action of 5 pseudo hearts.
Double closed in mammals (5):-
•blood pumped by muscular hearts, under high pressure = rapid flow rate.
•organs not in direct contact w/ blood but bathed in tissue fluod seeping out from thin-walled capillaries.
•blood contains O carrying resp pigment.
•blood pressure reduced in lungs-its pressure would be too low to make circulation in rest of body.
• so blood returns to heart and its pressure is raised again, to pump it to the rest of the body.
Right side of heart. Consists of all vessels concerned with pumping blood between heart and lungs.
Left side of heart, consists of all vessels concerned with pumping blood between the heart and body (exc lungs).
What occurs in pulmonary?
Right side pumps deoxy blood to lungs.
Oxy returns to left side of heart.
What occurs in systemic?
Left side pumps oxy blood to tissues.
Deoxy then returns to the right side.
4 advs of double circulation:-
•sustained high blood pressure in systemic.
•faster circulation in systemic.
•oxy and deoxy kept separate.
•increased O distribution which can maintain a higher metabolic rate.
What is the heart made of?
Specialised cardiac muscle which has its own blood supply and which is able to continuously contract and relax on its own.
How does heart muscle obtain the good supply of blood it needs for nutrients and O2 for contraction?
A dense capillary network that receives blood from coronary arteries.
Heart structure (4):-
•heart is, in effect 2 side by side pumps.
•left side of heart receives oxygenated blood from the heart and body and pumps it to the body.
• right side receives deox from body and pumps it to the lungs to pick up oxygen.
•2 thin walled collecting chambers (atria) above 2 thick-walled pumping chambers (ventricles).
What is the cardiac cycle?
The sequence of event that take place during one heartbeat.
What does the pumping action of the heart consist of?
Alternating contractions (systole) and relaxations (diastole).
How long does each cycle last in average?
What is cardiac output?
The volume of blood pumped around the body.
What 2 factors is cardiac output dependent on?
Stroke volume and heart rate.
What is stroke volume?
The volume of blood pumped by the left ventricle in 1 heartbeat (typical value for adult a rest = 75ml).
What is the typical adult heart rate?
How do you calculate cardiac output?
Stroke volume (ml) x heart rate (bpm)
What is the typical resting cardiac output?
4-6 litres per minute. Can rise to as much as 40l in highly trained endurance athletes.
What do valves do?
Prevent backflow of blood.
How do valves work?
Close under high pressure.
What are the 3 valve types in the cardio-vascular system?
•Atrio-ventricular valves (bicuspid and tricuspid).
•Semi-lunar valves- at the base of the aorta and pulmonary arteries.
•semi-lunar valves in all the veins.
What is blood made up of?
55% plasma and 45% cells.
What is plasma made up of?
90% water and 10% dissolved solutes eg CO2, O2, digested food products, plasma proteins, hormones, fibrinogen and antibodies.
What does plasma also have a role in?
Heat distribution throughout the body.
What is the other name for red blood cells? The
What is the other name for white blood cells?
What is RBC's large haemoglobing amouny for?
Transporting oxygen as oxyhaemoglobin
What is the benefit of RBC's flattened, biconcave disc shape?
Larger surface area so more O2 can diffuse across membrane. Thin centre reduces diffusion distance, speeding up GE.
Benfit of RBC's lack of nucleus or organelles:-
Maximises space for haemoglobin, allowing more O to be transported.
Benefit RBC's nearly as large as capillary 6-8um diameter:-
Slows blood flow to enable diffusion of O
What are the 2 white blood cell types?
Granulocytes and agranulocytes/lymphocytes.
Phagocytic and engulf bacteria to fight infection. Have lobed nuclei.
Produce antibodies and antitoxins to fight infection and provide disease immunity. Have spherical nuclei.
Large purple blob with fragmented shape within.
Large purple blob with round, solid shape inside.
Red blood cell appearance:-
Small red blob
What are the 5 blood vessel types?
What is the structural difference between arteries and veins?
Proportion of each layer is different and vein has a large irregular lumen compared to artery's small round lumen.
Artery and vein structure layers from outside to centre:-
Small round lumen in artery:-
Increases blood flow resistamce, helping maintain a high pressure as the blood gets further away from the heart's influence.
Single layer of cells producing a smooth lining to reduce friction and, therefore, resistance to flow.
Artery Tunica media:-
Contains elastin fibres and smooth muscle.
Thicker in arteries because it needs to withstand the high pressure of blood coming from the heart.
Allow artery walls to expand with each pulse of pressure/surge of blood (from LV contractiom). They then undergo elastic recoil which pushes the blood onwards- unidirectional flow so arteries don't need valves.
Smooth muscle contraction:-
Regulates blood flow and maintains pressure as the blood is transported further from the heart.
Contains collagen fibres which resist over stretching.
-carry blood away from heart.
-all carry oxygenates except pulmonary artery.
-all have high pressure bloos.
-no arteries have valves except aorta and pulmonary.
Branch off from arteries, similar structure but less elastic tissue and more smooth muscle.
Enables them to constrict and reduce blood flow through the tissue so it can be directed to where it is needed most.
How and why do single celled organisms e.g. amoeba transport the way they do?
Obtain nutrients and excrete waste via simple diffusion across the cell membrane. They can do this becsuse they have a short diffusion pathway and a low metabolic rate.
Lumen becomes narrower when the smooth muscle contracts, retrictong blood flow througj to the capillaries. Happens in the gut.
Lumen becomes wider when smooth muscle relaxes, increases blood flow through capillaries. Happens in muscles and skin surface.
Wider = less blood flow resistance which would impede return of blood to heart.
Vein tunica media:-
Thinner walls, less elastin because don't need to increase flow resistance by narrowing lumen = less muscle needed. No need to expand/ recoil as no surges of blood.
Blood flow through veins:-
•in veins above heart, blood returns via gravity.
•moves through other veins by the pressure of surrounding
•semi-lunar valves along length ensure flow in one direction.
Deoxygenated except in pulmonary vein. Low pressure.
What can faulty functioning of vein valves do?
Cause varicose veins and heart failure
Blood returned to the heart due to (4):-
•residual presure of blood during ventricular systole.
•massaging effect of skeltal muscles on veins (muscle pump).
•negative pressure in thorax during inspiration (suction effect).
•negative pressure due to atrial diastole. (Suction effect)
Subdivision of arterioles which form a dense network which penetrates all tissues and organs in body.
How is blood from capillaries returned to the heart?
Collected in venules which empty blood into veins which return it to the heart
Make walls permeable to water and solutes so it is at the capillaries that material exchange between blood and tissues takes place.
Capillary small diameter:-
Causes friction between blood and capillary walls, helping slow blood flow rate.
Many capillaries in capillary bed:-
Flow rate greatly reduced , giving plenty of time for material exchange with surrounding tissue fluid.
Solute exchange in capillary beds possible because (3):-
•Blood entering capillary network under high presure, forcing water and solutes out of the pores between the endothelial cells.
•cross sectional area of caps increases, increasing blood flow resistance, decreasing rate.
•loss of fluid from capillaries further decreases rate.
What is affinity?
The degree to which 2 molecules are atteacted to each other.
Hb binds W/ O in lungs and releases it in respiring tissues. When Hb and O2 combine they form oxyhaemoglobin.
How can Hb readily associate at alveoli and dissociate at respiring tissues to/from O2?
It can change its affinity for O2 by changing shapr.
What does each chain in Haemoglobin contain?
A prosthetic group- a non-protein part called a haem group, each containing an iron ion (Fe^2+). One O2 molecule can bind to each ion = 4 to each haemoglobin molecule.
What is partial pressure of a gas?
The pressure it would exert if it were the only one present . (pO2 and pCO2).
What is co-operative binding?
The increasing ease with which Hb binds its second and third molecules as the shape of the Hb changes.
How co-operative binding occurs:-
First O2 molecule binded changes Hb molecule's shape to make 2nd binding easier. Continues for second, doesn't occur with third so large increase in O2 partial pressure needed.
Graph plotted to show effect of increasing partial pressure on Hb:-
Produces sigmoid (flattened S-shaped) curve.
What causes partial pressure/Hb graph shape?
Co-op binding- difficult for Hb to load O2 at first but steep part shows increasing ease as Hb changes shape.
Look at tissue fluid image
Where does exchange between blood and body cells occur?
What does tissue fluid do?
Bathes surrounding cells, supplying them with solutes and removes cell waste.
What is tissue fluid formation dependent on?
Balance between 2 opposing forces:-
•hydrostatic pressure (blood pressure).
•osmotic pressure (solute potential).
Tissue fluid at arteriole end of tissue bed:-
Blood under high pressure from pumping action of LV and artery + arteriole wall contraction. High hydrostatic pressure pushes fluid out of CP to spaces surrounding cells (ultrafiltration). HS pressure falls. Cells + plasma proteins too big to leave capillaries, lowering water pot in blood, increasing solute pot, drawing fluid back into CP by osmosis. HS is however greater than osmotic force so net movement = fluid leaving CP into tissues.
Tissue fluid at venous end:-
HS pressure lost bc so much fluid lost. Water pot is lower (solute pot higher) than tissue fluid due to plasma protein conc. Osmotic force drawing fluid back into capillary is greater than HS pressure so net movement is fluid returning to capillaries by osmosis.
Lymph vessels = draim for the 1% excess fluid. V. Thing walls so fluid can easily diffuse inside, forming lymph. Lymph eventually returns to venous system via thoracic duct where it empties into a vein near the heart.
How can insufficient protein in diet lead to a swollen abdomen?
•leads to a reduction in the amount of plasma proteins in blood.
•this means blood in CP will not have low water pot so no water pot grad is generated.
•water won't be absorbed back into venous end of capillaries. Lymph vessels won't be able to cope w/ the excess fluid and it will accumulate in the tissue.
High blood pressure:-
Higher HA pressure increases the amount of IC fluid formed. Lymph vessels can't drain excess fluid ao it accumulates, usually in lower lega due to gravity. Accumulation of fluid can also occur due to blockages in lymph system.
•can occur when friction causes capillary wall damage, causing pore enlargement and allowing plasma proteins into tissue fluid.
•blood in CP doesn't need to have a low water pot, so no water pot is generated and water stays within tissue fluid.
•lymph vessels can't drain excess fluid and it accumulates.
Takes oxygenated blood from left ventricle of heart to body
Brings oxygenated blood from lungs to left atrium
Takes deoxygenated blood from body to heart (right atrium)
Takes deox blood from heart right ventricle to lungs
Coronary artery/coronaey vein:-
Heart's own blood supply
Blood flow pathway:-
Lungs (oxygenated blood)
Body (deoxygenated leaves)
3 stages of cardiac cycle:-
Atrial systole (6):-
•atria contract, decreasing vol.
•atria pressure increases.
•pressure im atria higher than ventricles.
•atrio-ventricular (tricuspid + bicuspid) valves are forced open.
•blood flows into ventricles from the atria down a pressure gradient.
Ventricular systole (7):-
•ventricles contract, decreasing vol.
•pressure in ventricles increases.
•pressure in ventricles is higher than the atria.
•this closes atrio-ventricules valves to prevent backflow (heart sound LUB).
•high pressure opens semi-lunar valves.
•blood flow into the pulmonary artery and aorta down a pressure gradient.
Ventricular and atrial diastole (6):-
•atria + ventricles relax.
•this increases vol and lowers pressure in heart chambers.
•higher pressure in aorta and pulmomary arteries than in the heart chambers.
•this closes semi-lunar valves to prevent backflow (heart sound DUB)
•blood flows into atria from vena cava and pulmonary vein down a pressure grad.
•cycle starts again
What is an electrocardiogram (ECG)?
A trace of voltage changes produced by the heart, detected by electrodes on the skin.
What does the P wave show in an ECG?
Voltage generated by the SAN (associated with atria contraction).
Time between start of P wave and start of QRS complex on ECG?
PR interval. Time taken for AVN to pick up and pass on wave of excitation from atria to ventricles.
QRS complex on ECG:-
Shows depolarisation and contraction of ventricles. Bigger amplitude than P due to more muscle.
ST segment on QRS:-
End of S wave to start of T wave.
T wave on ECG:-
Repolarisation of ventricles.
Isoelectric line on ECG:-
Baseline of trace between T and P of cycles.
Calculate heart rate from ECG:-
QRS complexes over a 6 second interval x 10
ECG showing atrial fibrillation:-
P wave may be absent
ECG post heart attack:-
May be a wide QRS complex.
ECG showing enlarged left ventricle:-
May have a QRS complex showing greater voltage change.
ECG showing changes in ST segment and T wave:-
May be related to insufficent blood delivery to heart muscle e.g. In patients with blocked coronary arteries and atherosclerosis.
Cardiac muscle is myogenic. What does this mean?
It can initiate its own electrical impulse, rather than depending on signals from nerves. *can still be modified by certain hormones/the nervous system.
Heart's 2 areas of specialised cells which are important in controlling heart rate:-
Sinoatrial node (SAN).
Atrioventricular node (AVN)
Acts like a pacemaker, setting the rhythm of the heart by sending regular waves of electrical stimulation to the atrial walls. Causes synchronised atrial contractions-atrial systole.
After ventricles fill, picks up wave of excitation and passes it onto specialised tissue strand (Bundle of His), which transmit it to ventricles' apex. Here, the bundle branches into Purkinje fibres, located in ventricle walls.
Where is SAN?
Wall of right atrium
Where is AVN?
Between the 2 atria.
What do the Purkinje fibres do?
Carry wave of excitation upwards through ventricle muscle. Causes ventricular systole, contracting from the apex upwards and forcing the blood from the ventricles into the aorta and pulmonary artery.
3 ways CO2 transported in blood:-
•In solution in plasma (5%).
•Bound to haemoglobin as carbamino-haemoglobin (10%).
•as HCO3^- ion in plasma (85%)
Reactions in RBC (6):-
•CO2 from respiring cells diffuses in.
•CO2 reacts w/ water, forming carbonic acid. Reaction catalysed by carbonic anhydrase.
•carbonic acid dissociation into H^+ and HCO3^- ions.
•HCO3 ions diffuse out into plasma (where they combine w/ Na). Chloride ions diffuse into RBC to maintain electrochemical negativity. *chloride shift.
•H+ ions cause oxyhaemoglobin to dissociate into O and Hb. H+ combines with Hb to haemoglobonic acid, maintaining pH of RBC.
•O diffuses out of RBC
The influx of chloride ions into RBCs to maintain electrical neutrality
Why is most CO2 carried as HCO3?
Fastest way of dealing with it
Blood flow through veins:-
As skeletal muscles contract, blood beyond contraction is forced towards heart, opening valves. Valves behind forced away.
As skeletal muscles contract, blood pushes back against the valves, causing them to close and prevent blood from being forced away from heart again.
During exercise muscles need more ATP, respiration rate increases. CO2 production increases, lowering blood pH. Dissociation curve shifts to right. Hb has lower O2 affinity so higher pCO2 at x % sat of haemoglobin.
Organisms that live in low pO2 environments:-
Have resp pigments with higher O2 affinity e.g Lugworms in sand and llamas at high altitude.
Resp pigment found in muscle fibres. Very high O2 affinity. Higher % sat than Hb so retains its O2 until v. Low pO2. Delays less efficient anaerobic respiration.