Transport in animals Flashcards
haemocoel
the main body cavity found in most invertebrates that contains a circulatory fluid
What do transport systems have
- medium - to carry dissolved substances
- pump - move materials
- respiratory pigment eg haemoglobin (not insects) - to carry dissolved gases
- system of vessels with valves to ensure on way flow
What is an open circulatory system what organism has this
- blood does not move around the body in blood vessels
- cells are bathed by blood or a fluid called haemolymph in a fluid filled space around the organs called a haemocoel return slowly to the dorsal - tube shaped heart
- no need for a respiratory pigment as oxygen is supplied directly to tissues via the tracheal system
- insects
why are open circulatory systems often ineffecient
don’t control the distribution of respiratory gases
What is a closed circulatory system
- use blood vessels
What is an advantage to closed circulatory systems
- use blood vessels
- blood can be transported more quickly under higher pressure to all parts of the animal’s body
What are the two types of closed circulatory systems
- single
- double
What is a single circulatory system
- involves blood passing through the heart once during its passage around the body
What sort of circulatory system is found in fish
- single closed
- blood pumped to the gills and onto the body organs before returning to the heart
What sort of circulatory systen is found in an earthworm
- single closed
- five pairs of pseudohearts (thickened muscular blood vessels) pump blood from the dorsal vessel to the ventral vessel
What is a double circulatory system
- involves blood passing through the heart twice
What is the circulatory system found in mammals
- double closed
- pulmonary circulation supplies the lungs where blood is oxygenated
- systematic circulation supplies body with oxygenated blood
What are the advantages of a double circulatory system over single
- meets demand of mammals with high metabolic rates
- a higher blood pressure and faster circulation can be sustained in a systematic circulation
- oxygenated and deoxygenated blood are kept seperate which improves oxygen distribution
What is the function of arteries and describe the adaptations as well as change in pressure and rate of blood flow
- carry blood away fro the heart
- thick walls to resist high blood pressure
- elastic fibres stretch to allow the arteries to accommodate blood and the elastic recoil of the ffribres pushes blood along the artery
- the pressure in these arteries rythmically rise and fall corresponding to verntricular systol
- as blood flows along the artery friction with the vessel walls cause blood pressure and rate of blood flow to decrease
How are arterioles formed and what are the adaptations of an arteriole as well as change in pressure and rate of blood flow
- main arteries continually branch to form smaller arteries and eventually arterioles
- arterioles have a large total surface area and relativley narrow lumen causing further reduction in pressure and rate of blood flow
- smooth muscle tissue whcih widen or narrow the lumen to increase or decrease blood flow
What are the function of capillaries annd what are it’s adaptations as well as change in pressure and rate of blood flow
- million of capillarie to form dense networks in tissues
- have narrow lumer but there total cross sectional area is very large
- as blood flows throught the capillaries both blood pressure and rate of blood flow decreae
- due to the increase in total cross sectional area and frictional resistance of blood flowing along the blood vessels
- there function is to supply oxygen and nutrients and absrobe carbon dioxide and waste
What are venules describe it’s adaptations as well as change in pressure and rate of blood flow
- small veins that converge forming larger venules and eventually veins
- similar structure to veins and as they widern resistance to blood flow decreaes allowing blood rate of flow to increase again
What are the function of veins it’s adaptation as well as change in pressure and rate of blood flow
- they carry blood back to the heart
- semi lunar valves prevent backflow of blood ensuring blood travels in one direction only
- although pressure in veins is low blood is returned to the heart due to the effects of surroudning skeletal muscle contracting squeezing the vein reducing the volume increasing pressure inside the vein forces blood through the valves
Describe the blood flow through the heart
- blood enters the heart from the head and body via the vena cava in the right atrium
- the right atrium contracts (atrial systole) forcing blood through the right atrio ventricular valve into the right ventrile which is relaxed
- the right ventricle contracts (ventricular systole) forcing blood out of the heart through the right semi lunar valve to the lungs via the pulmonary artery
- oxygenated blood returns from the lungs to the heart via pulmonary vein and enters the left atrium when the left atrium is relaxed (total diastole)
- the left atrium contract forcing blood through the left atrio ventricular valve into the left ventricle which is relaxed
- the left ventricle contracts forcing blood out through the left semi lunar vavle into the aorta and then to the rest of the body
systole
contraction
What does the blood flow through the heart show
- describes one circuit blood takes during the cardiac cycle both atria contract simulataneeously followed by the contraction of both ventricles
diastole
relaxation
What are the function of valves
ensure blood flows in an unidirectional manner - prevent the backflow of blood
Describe the cardiac cycle
- left atrium contracts so volume of atrium decreases and pressure increases
- when blood pressure in left atrium exceeds that in left ventricle blood flows into the left ventricle
- the ventricle then contracts (ventricular systole) and pressure rises in the left ventricle as volume decreases
- as the ventricle contracts blood is pushed against the atrioventricular valves closing them and preventing vlood flow back to the atria
- when pressure in left ventricle exceeds that in the aorta the left semi lunar valves opens and blood flows out into the aorta
- left ventricle then relaxes (diastole) so it volume increases and pressure falls
- when pressure in ventricle dropve below that o the aorta blood tries to flow back into the ventricle from th aorta pushing against left semi lunar valve and closing it
- when pressure in left ventricle drops below that in left atrium the left atrio ventricular valve opens and the cycle begins again
- blood always flow from high pressure to low unless a valve prevents it
bundle of his
modified cardiac muscle fibre paing from the AVN to the base of the ventricle through the septum of the heart
purkinje fibres
network of fibre in the wall of the ventricles
What is the special feature of the heart
- myogenic
- heart beat is intiated within the cardiac muscle itself and is not dependednt upo external stimulation
Describe how atrial systole is bought about
- wave of excitation spreads out from the sinoatrial node across both atria
- both atria start contracting
- wave cannont spread to ventricle due to layer of connective tissue
- wave spreads via atrioventricular node (AVN) through the bundle of His to the apex of ventricle
Describe how ventricular systole is bought about
- bundle of his branches into purkinje fibres carrying the wave upwards though ventricle muscle causing it to contract
- ventricla contraction is therfore delayed and contracction is from base upwards
What does ECG stand for
electrocardiogram
What is the p wave
voltage change associate with contraction of atria
What is the QRS complex
depolarisaiton and contraction of ventricles
What is the T wave
repolarisation of ventricle muscles
What is the isoelectric line
filling time the gap beetween t and the next p wave
What does blood consist of
- plasma
- cells
- red blood cells -erythrocytes contain haemoglobin
- white cells and platelets
Describe the structure and adaptation of red blood cells and why it is useful in humans
- bioconcave shape
- increases the surface area or the absorption and release of oxugen and do not poses a nucleus
- they can carry more haemoglobin but limits they’re life so they have to be continually produced
What are the two types of white blood cells
- granulocytes - phagocytic
- lymphocytes - develop in cells that produce antibodies
What does plasma contain and it’s function
- plasma is 90% water and contains dissolved solutes eg glucose and amino acids, hormone and plasma proteins
- responsible for the distribution of heat and transport of carbon dioxide as hydrogencarbonate ions
- excretory products such as urea are also transported dissolved in the plasma
partial pressure
of a gas the pressure it would exert if it was the only gas present
How is oxygen transported
- haemoglobin binds to oxygen in the lungs and release it to the respiring tisues
- oxygen + haemogblobin <-> oxyhaemoglboin
- association and dissociation of oxygen with haemoglbin is influenced by a number of factor and is shown by a dissociation curve
Describe how oxygen binds to haemoglobin
- each molecule ca accomodate four molecules of oxygen (4O2) one attatched to each of the four haem groups
- as oxygen molecules bind the haemoglobin molecule changes slightly making it easier for the next one to bind - cooperative binding seen by the steep part of the curve
- the fourth and final oxygen molecule is more difficult to bind and requires a large increase in partial pressure of oxygen to accomplih this shown in the plateu on the graph fiving curve a sigmoid shape
affinity
the degree to whcih two molecules are attracted to each other
Describe wht the sigmodial curve for partial pressures of oxygen shows
- how haemoglobins affinity for oxygen changes with partial pressure
- at high partual pressures the affinity is high so oxyhaemoglobin does not eaily release it oxygen
- at low partial pressures oxygen is released rapidly to the respiring tissues where it is needed because haemoglobins affinity for oxygen is low
Describe how haemoglobin is adapted for low oxygen environments and give examples of animals and the environment
- low oxygen environments - high altituds of muddy burrow
- animals have adapted haemoglobin for having a higher affinity for oxygen than normal haemoglobin
- llamas and lugworm dissociation curves move to the left of the normal meaning that their heamoglobin is more saturated at the same partial pressure of oxygen than normal - more able to pick up oxygen
Describe how foetal haemoglobin is different to normal haemoglobin
- higher affinity for oxygen than normal and so is to the left of normal
- means able to absorb oxygen from the mothers blood via the placenta
What is the bohr effect
- the momevement off the oxygen dissociation curve to the right as the result of higher partial pressure of carbon dioxide
- haemoglonin shows reduced affinity for oxygen
When does the haemoglobin dissociation curve shift to the right and why
- when carbon dioxide concentrations in the blood rise during excercise
- as haemoglobins affinity for oxygen is reduced so more oxygen is released at the same partial pressure of oxygen
- this supplies oxygen more quickly to respiring tissues where it is needed and is called the bohr effect
What are the three ways carbon dioxide is carried
- dissolved in plasma
- as HCO3- ions in the plasma
- bound to haemoglobin as carboamino- haemoglbin
Describe how carbon dioxide is transported as hydrogen carbonate ions
- carbon dioxide diffuses into the red blood cell
- carbonic anhydrase catalyses the reaction between carbon dioxide and water forming carbonic acid
- carbon acid dissocites into HCo3- and H+ ions
- HCO£- diffuses out of the red blood cell
- Cl - ions diffuse into the cell to maintain the electrochemical neutrality this is called the chloride shift
- H+ ions combie with oxyhemoglobin forming haemoglobnic acid HHb
- oxygen diffuses out of the cell
Give a brief description of how tissue fluid is formed
- from the plasma found in the blood
- contain water, salts, glucose, amino acids and disolved oxygen and bathes the cells in the capillary bed
Describe how tissue fluid is formed
- hydrostatic pressure creeated by blood pressure at the arteriole end forces these materials out of the capillaries through the pores in their walls plasma poteins are too large to leave. the water potential of the blood is lower than that of the tissue fluid tending to draw water into the capillary and this decreases along the capillart as water leaves this is less than hydrostatic pressure so net movement is out of the capillaries
- most of the water is reabrobed by osmosi at the venule end of the capillary bed here omotic pressure created by water potential gradient exceeds hydrostatic pressure in capillaries so net movement of fluid is into the capillary carbon dioxide is reabsorbed by diffussion
- excess tissue fluid drains into the lymphatic system and returns to the venous system via the thoracic duct whcih empties into the left subclavian vein the neck
