Topic 3: Exchange + Transport: Transport in Animals Flashcards
Why are specialised transport systems needed?
Specialised transport systems are needed because:
-Multicellular animals have high metabolic demand
-Surface area: volume ratio gets smaller as organisms get larger (diffusion distances longer)
-Molecules eg hormones/enzymes may be made in one place but needed in another
-Food will be digested in one organ system but needs to be transported to every cell eg for respiration
-Waste products of metabolism needs to be removed from cells and transported to excretory organs
Common features of circulatory systems
Common features of circulatory systems:
-Liquid transport medium that circulates around system eg blood
-Vessels that carry the transport medium
-Pumping mechanism to move fluid around the system
Why do organisms such as humans require a mass transport system?
Large multicellular organisms such as humans require a mass transport system due to being multicellular and having a small surface area to volume ratio
Mass transport definition
Mass transport = substances transported in a mass of fluid with a mechanism that moves the fluid around the body
Open circulatory systems
Open circulatory systems:
-Very few vessels
-Pumped straight from heart to body cavity (the haemocel) - where blood is under low pressure and comes into direct contact with cells
Insect blood
Insect blood is called haemolymph, which carries food and nitrogenous waste products rather than oxygen or carbon dioxide
Closed circulatory systems
Closed circulatory systems - blood enclosed in blood vessels and doesn’t come into direct contact with body cells
-Substances leave and enter blood by diffusion through blood vessel walls
Single closed circulatory systems
Single circulatory systems - blood travels through the heart once through each complete circuit
-Passes through two sets of capillaries (1st set = exchanges oxygen and carbon dioxide, 2nd set = substances exchanged between blood and the cells)
Double closed circulatory systems
Double closed circulatory systems - Blood passes through the heart for each complete circuit
-1st circuit: blood pumped from heart to lungs to pick up oxygen and unload carbon dioxide then returns to the heart (pulmonary circulation)
-2nd circuit: Blood flows through heart and pumped to travel whole body before returning to heart (systemic circulation)
Components of blood vessels
Components of blood vessels:
-Elastic fibres - composed of elastin, stretches and recoils, provides vessel walls with flexibility
-Smooth muscle - contracts and relaxes, changes size of lumen (the channel within the blood vessel)
-Collagen - provides structural support to maintain the shape and volume of the vessel
Artery functions
Arteries carry oxygenated blood (except in pulmonary artery) away from the heart to the tissues of the body
-Blood under higher pressure than in the veins
Elastic fibres in artery walls
Elastic fibres enable arteries to withstand the force of blood pumped out the heart and stretch to take the larger blood volume
-They recoil in between heart contractions then return to normal length to help even out blood surges to give a continuous flow
Endothelium of arteries
The endothelium of arteries have smooth lining to allow for flow of blood
Arterioles
Arterioles - branch of arteries
-They have more smooth muscle and less elastin in their walls than arteries due to having little pulse surge, but constricts and dilates to control flow of blood into organs
Smooth muscle in arterioles
Smooth muscle in the arterioles contracts to constrict the vessel and prevents blood flow into a capillary bed (vasoconstriction), or relaxes to allow blood flow through a capillary bed (vasolidation)
Vasoconstriction
Vasoconstriction - smooth muscle in arterioles contract to constrict vessels and prevent blood flow into a capillary bed
Vasolidation
Vasolidation - smooth muscle in arterioles relaxes to allow blood flow through into the capillary bed
Capillary lumen
The lumen of capillaries is so small that red blood cells have to travel through in single file
How do substances pass out capillaries?
Capillaries have gaps between their endothelial cells that are large enough for substances to pass out capillaries and into the surrounding fluid
Capillary adaptations
Adaptations of the capillaries:
-Large surface area
-Total cross-sectional area of capillaries greater than arteriole supplying them - slows rate of blood flow - to give more time for exchange of materials by diffusion
-Walls are single endothelial cell thick to give thin layer for diffusion
Veins function
Veins carry blood away from cells towards the heart and carry deoxygenated blood (except pulmonary vein and umbillical vein)
Inferior vena cava location
The inferior vena cava is in the lower parts of the body
Superior vena cava location
The superior vena cava is found in the upper parts of the body
Why do veins not have a pulse?
Veins do not have a pulse as the surges from the heart pumping are lost as the blood passes through the narrow capillaries
Main adaptations that enable low blood pressure to be carried back into the heart against gravity
Adaptations:
-Valves = closes to prevent the backflow of blood
-Bigger veins run between big active muscles - muscles contract to squeeze the veins and force blood towards heart
-Breathing movements - acts as pump
Platelets
Platelets = fragments of large cells called megakaryocytes found in red bone marrow - involved in clotting mechanism of the blood
Functions of the blood
Function of the blood - maintenance of body temp + acts as buffer to minimise pH changes +
transport of:
-Oxygen to and carbon dioxide from respiring cells
-Digested food from the small intestine
-Nitrogenous waste products from cells to the excretory organs
-Chemical messages (hormones)
-Food molecules from storage compounds to cells that need them
-Platelets to damaged areas
-Cells and antibodies involved in the immune response
Plasma proteins
Plasma proteins have an osmotic effect, where they give the blood in capillaries a high solute potential (so a low water potential) compared to surrounding fluid, and so water moves into blood in the capillaries from surrounding fluid by osmosis
Oncotic pressure definition
Oncotic pressure is the tendency of water to move into the blood by osmosis (about -3.3kPA)
Hydrostatic pressure definition
Hydrostatic pressure - blood being under pressure due to blood surges that occur when the heart contracts
Movement of tissue fluid
-Hydrostatic pressure at the arterial end of the capillary is higher than oncotic, so fluid leaves out of the capillaries
-Hydrostatic pressure falls as the venous end as fluid has moved out and the pulse is lost. As the oncotic pressure is higher (still -3.3kPA), water moves back into the capillaries
Lymph
Lymph - 10% of tissue fluid leaves the blood vessels and drains into a system of blinded tubes called lymph capillaries
-Similar in composition to plasma and tissue fluid but have less oxygen and fewer nutrients, and contains fatty acids
Lymph nodes
Lymph nodes are found along the lymph vessels. Lymphocytes build up in these nodes when necessary and produce antibodies which are passed into blood
-Lmpyh nodes are enlarged - sign that the body is fighting off invading pathogens
Erythrocyte adaptations
Adaptations of erythrocytes:
-Biconcave shape - large surface area + helps them to pass through narrow capillaries
-Lack of nuclei = maximises space for haemoglobin (however this limits their life to 120 days in the bloodstream)
Haemoglobin makeup
Haemoglobin:
4 polypeptide chains - each with iron-containing haem prosthetic group - each binds to an oxygen molecule
Oxygen + haemoglobin
Oxygen + haemoglobin = oxyhaemoglobin
Positive cooperativity / cooperative binding
Positive cooperativity / cooperative binding : Arrangement of the haemoglobin molecule allows them to bind to oxygen molecules and then change shape, making it easier for the next oxygen molecule to bind
Effect of a drop in oxygen levels in respiring tissues
Effect of a drop in oxygen levels in respiring tissues:
Oxygen will release rapidly from haemoglobin to diffuse into the respiring cells
-This effect is enhanced by the low pH in the tissues compared with the lungs
Effect of increasing haemoglobin saturation with oxygen
As haemoglobin becomes increasingly saturated with oxygen, the partial pressure increases, and more oxygen is picked up
What happens to oxygen carried in the erythrocytes for when you aren’t active?
When you aren’t active, 25% of oxygen carried in the erythrocytes is released into the body cells and the rest acts a reservoir when the body demands increase suddenly
Bohr effect
Bohr effect - carbon dioxide partial pressure increases, and so haemoglobin gives up more oxygen more easily
Result of the bohr effect
Result of the bohr effect:
-In active tissues with a high partial pressure of carbon dioxide, haemoglobin gives up its oxygen more rapidly
-In the lungs where the proportion of carbon dioxide in the air is relatively low, oxygen binds to the haemoglobin molecules more easily
Fetal haemoglobin
Fetal haemoglobin has a high affinity for oxygen, so it removes oxygen from the maternal blood as their blood moves past eachother
3 different ways that carbon dioxide is transported from the tissues to the lungs
3 different ways that carbon dioxide is transported from the tissues to the lungs:
-5% = dissolved in plasma
-10-20% = combined with amino groups in the polypeptide chains of haemoglobin = forms carbaminohaemoglobin
-75-80% = converted into hydrogen carbonate ions in the cytoplasm of rbc
Formation of carbonic acid
Carbon dioxide reacts slowly with water to form carbonic acid, increased by the aciton of carbonic anhydrase
Dissociation of carbonic acid
Carbonic acid partially dissociates to form hydrogen ions and hydrogen carbonate ions
Chloride shift
The chloride shift is when negatively charged hydrogen carbonate ions move out of erythrocytes into plasma by diffusion, and so negative chloride ions move into erythrocytes to maintain the electrical balance
Effect of removing carbon dioxide and converting it into hydrogen carbonate ions
Removing carbon dioxide by converting it into hydrogen carbonate ions maintains a steep concentration gradient for carbon dioxide to diffuse from respiring tissues into erythrocytes
Haemoglobonic acid
Haemoglobin acts as a buffer and prevents changes in the pH by accepting free hydrogen ions in a reversible reaction to form haemoglobonic acid
Cardiac muscle
Cardiac muscle is what the heart is made up of, and contracts and relaxes in a regular rhytm involuntarily
Coronary arteries
Coronary arteries supply the cardiac muscle with oxygenated blood to keep it contracting and relaxing all the time
Role of the inelastic pericadial membranes that surround the heart
The inelastic percadial membranes helps prevent the heart from over-distending (expand/enlarge) with blood
Why does the left side of the heart have more muscular walls than the right side of the heart?
The left side of the heart has to produce sufficient force to overcome the resistance of the aorta and move the blood under pressure to the whole of the body
Why is the foremen ovale open in the fetus before birth?
The foremen ovale is open in the fetus before birth as their lungs are not yet functioning, and so blood is not completely oxygenated, meaning the blood mixes freely in the heart
Atrial systole
Atrial systole:
-Both atria contract, increasing the blood pressure
-This causes the atrioventricular valves to open and the semilunar valves close
-When these valves open, blood is forced in to the ventricles
Ventricular systole
Ventricular systole:
-Blood pressure inceases in the ventricles as blood enters from the atria and through the atrioventricular valves
-As pressure is higher infront of the AV valves, they close, and the semilunar valves open
-Blood leaves through the semilunar valves and through either the aorta (left) or the pulmonary artery (right)
Diastole
In diastole, the atria and ventricles relax. The blood starts to fill the heart, and the volume/pressure of blood increases
How can we hear the sounds of the heart beating
Sounds of the heart beating is caused by the blood pressure closing the heart valves (lub-dub)
-Lub = blood forced against the av valves as the ventricles contract
-Dub = Backflow of blood closing the semilunar valves
Why is cardiac muscle myogenic?
Cardiac muscle is myogenic as it doesn’t require action of nerve cells and beats involuntarily
Action of the sino-atrial node (SAN)
The SAN sends a wave of depolarisation, causing the atria to contract and therefore initiating the heartbeat
Action of the atrio-ventricular node (AVN)
The AVN picks up the wave of depolarisation, imposing a slight delay before stimulating the bundle of His
Wave of electrical depolarisation in the heart
Wave of electrical depolarisation in the heart:
1) Wave of electrical depolarisation initiated by SAN, causes atria to contract
2) Wave picked up by AVN, imposing a slight delay before stimulating the bundle of His
3) Electrical activity passed to the apex of the purkyne fibres and triggers the ventricles to contract
Bundle of His
The bundle of His is a bundle of conducting tissue made up of purkyne fibres
Function of an ECG
ECG measures the electrical acitivty of the heart by measuring the tiny electrical differences in your skin
Tachycardia
Tachycardia - rapid heartbeat above 100bpm (often normal eg due to exercise)
Bradycardia
Bradycardia - heart rate slows down to below 60bpm (usually due to being fit, but can be severe and may require an artificial pacemaker)
Ectopic heartbeat
Ectopic heartbeat - extra heartbeats that are out of the normal rhythm
Atrial fibrillation
Atrial fibrillation - examples of arrhythmia - abnormal rhythm of the heart - rapid electrical impulses in atria, but they don’t contract properly so only some of the impulses are passed on to the ventricles, so the heart doesn’t pump effeciently
Hepatic portal vein
In the hepatic portal vein, blood does not go straight back to the heart, as it allows blood from gut to flow to liver
Myogenic contraction
Myogenic contraction: myocytes (muscle cells) in the heart has polarized charge across their membrane
-Reversing the charge (depolarizing) causes contraction
Cardiac output calculation
Cardiac output = stroke volume x heart rate
Varicose veins
Varicose veins: weakened vein wall causes valves to not close properly > backflow of blood > vein becomes enlarged and bumpy
How to measure heart beats on an ECG diagram
How to measure heart beats on an ECG diagram:
-One square = 0.2s
-Measure time between start of one P wave (of atrial systole) to the start of the next P wave. Divide 60 by this number.
P,Q,R,S,T waves on ECG
P wave = Atrial systole
QRS = Ventricular systole
T = diastole
Stroke volume
Stroke volume is the volume of blood pumped out of a ventricle in each contraction
-Measured in cm cubed
Cardiac output unit
Cardiac output = Cm cubed per min
Differences between the circulation systems of mammals and fish
Differences between the circulation systems of mammals and fish:
-Mammals: Systemic+Pulmonary circuit (double), blood is maintained at higher pressure, blood passes through one set of capillaries
-Fish: Single system, blood pressure is maintained at lower pressure, blood passes through to sets of capillaries
Difference between the structure of arteries, veins and capillaries
(note: include their functions in an exam question)
-Arteries: Lots of collagen for structural support, lots of smooth muscle that contracts and relaxes to control blood pressure
-Veins: More collagen than arteries to give structural support as they carry larger volume of blood, thicker lumen
-Capillaries: Lumen diameter slightly large than rbc to ensure they travel in single file, and to increase contact of rbc with capillary walls
Why do veins have a thicker lumen?
Veins have a thicker lumen to reduce resistance and friction, so to maintain a constant flow of blood to the heart
Why do arteries have a smaller lumen than veins?
Arteries have a smaller lumen to maintain their blood pressure (high)
Difference between the circulatory systems of amphibians (eg frogs) and humans
-Amphibians (eg frogs): Blood is mixed in the heart, single circulatory systems, less effective circulation as there is less oxygen for body cells
-Humans: Blood is separate in heart, double circulatory system, cells get more oxygen for cells, blood never mixes as it is separates in the lungs
Why does the oncotic pressure of the blood rely only on the concentration of plasma proteins?
Oncotic pressure of the blood relies only on the concentration of plasma proteins because:
-Large plasma proteins cannot pass through capillary wall
-Imbalance of large plasma proteins between blood and tissue fluid results in the oncotic pressure
Effect of reducing plasma albumin concentration
Reducing plasma albumin concentration will decrease the oncotic pressure which increases the net movement of fluid
What can cause red, swollen skin?
Red, swollen skin can be due to inflammation caused by the increased bloodflow from vasolidation, so that immune cells can go to infected tissue (red). More tissue fluid causes swelling (oedema).
What causes the blood to stop when someone is injured ie cut their hand?
Exposure of blood/platelets to collagen in damaged blood vessel causes clotting, which prevents bleeding and produces scabs
What can cause discomfort under your collarbone/armpit area when injured/infected?
Excess tissue fluid drains into lymph vessels , pathogens enter fluid - fluid is transported along lymph system to lymph nodes - activity of phagocytes + lymphocytes causes swelling of lymph nodes (discomfort in collarbone/armpitarea)
Similitaries between ultrafiltration of the kidneys and tissue fluid?
Similarities between ultrafiltration in the kidneys and tissue fluid:
-Small molecules filtered out blood
-Both occur in capillaries
-High hydrostatic pressure in both processes
Differences between ultrafiltration of the kidneys and tissue fluid
Differences between ultrafiltration of the kidneys and tissue fluid:
-In the kidneys, molecules are not reabsorbed by capillaries from urine (but will form lymph)
-In ultrafiltration, blood is filtered through three layers wheras in tissue fluid, blood is filtered thorugh one layer
-Knot of capillaries in kidneys, network of capillaries in formation of tissue fluid
Visibility of the structures in the heart when there are no atria (in dissection)
Visibility of the structures in the heart when there are no atria (in dissection):
- Not visible = AV valve, pulmonary vein, purkyne fibres, SA node, bundle of His
- Visible = Left ventricular walls, Semilunar valve, septum
Why is there a higher unloading of oxygen at respiring tissues, causing the curve on oxygen dissociation curves to shift to the right?
At respiring tissues > partial pressures of carbon dioxide are high > decreased oxygen affinity > therefore haemoglobin unloads more oxygen
Why does the haemoglobin of llamas load up on more oxygen?
Llamas - live at high altitutes where partial pressure of oxygen is low > so their haemoglobin has to have a high oxygen affinity to load up on oxygen
What is positive cooperativity / co-operative binding of haemoglobin?
Positive cooperativity = when one oxygen binds, the quaternary structure of haemoglobin molecules change -> increased affinity of haem groups for oxygen -> binding more molecules requires small increase in partial pressure
Animals that have open circulatory systems
Most invertebrates (except earthworms, octopuses and squids) have open circulatory systems
Effect of superventricular tachycardia (ventricle walls contracting twice after every atrial contraction)
less blood leaves the heart; ventricles do not have time to fill before contracting
Why erythrocytes can’t enter into capillaries?
Erythrocytes are too large to enter through capillary walls; gaps between endothelium cells too small
Health definition
Health = physical or mental state of an individual; absence of disease
How components of tobacco smoke can effect the cardiovascular systems of smokers
How components of tobacco smoke can effect the cardiovascular systems of smokers:
-Nicotine = increases stickiness of platelets = blood clot formation = release of adrenaline = constriction of arterioles = reduced blood flow
-Carbon monoxide = combines permanetly with haemoglobin (carboxyhaemoglobin) = reduced oxygen carrying capacity of blood
-Increased heart rate/blood pressure
-Damage to lining/endothelium
-CHD
Subunits that the protein of fetal haemoglobin is made up of
The protein in fetal haemoglobin is made up two of alpha subunits, and two gamma subunits rather than beta - the gamma subunits increase the haemoglobin’s affinity for oxygen
