Transport in Animals Flashcards
what substances are transported in animals?
blood, oxygen, R/WBC, glucose, CO2, hormones, vitamins and amino acids
what do transport systems consist of?
blood, heart, blood vessels
why do some animals not need a transport system?
diffusion- large surface area to volume ratio
what are the reasons for a transport system?
- need a supply of oxygen and glucose
- removes waste product
- diffusion is not fast enough for multicellular organisms
what are the three key factors for a transport system?
- size
- level of activity
- surface area to volume ratio
why is size relevant in relation to a transport system?
- several layers of cells prevent fast diffusion
- diffusion is not sufficient for needs - increased distance
- hormones/ enzymes made in one place, needed in another
- oxygen taken in one place and needed everywhere
- waste from cells to excretory organs
why is level of activity relevant in relation to a transport system?
- active animals require more oxygen for respiration
- must be delivered quickly if the organism is metabolically active
why is surface area to volume ratio relevant in relation to transport system?
- large multicellular organisms have a smaller surface area to volume ratio so surface area is not enough to absorb/ remove substances
- diffusion distance to inner cells has also increased as volume of an organism is larger
what are the components of a circulatory system?
- pump to move fluid
- circulatory fluid/ transport medium
- interconnecting vessels
what is a closed circulatory system?
- blood confined in blood vessels
- heart pumps blood under pressure into vessels which branches off and infiltrate organs before returning to the heart
what is an open circulatory system?
when there are very few vessels to contain the transport medium and is pumped straight from the heart into the body cavity of the animal
what is a double circulatory system?
- blood flows through the heart twice on one circuit of the body (vertebrates, echinoderms and squid)
- 2 circuits
- pulmonary circuit- carries deoxygenated blood to lungs to
collect oxygen and excrete CO2
- systematic circuit- carries oxygenated blood to cells
what are some examples of processes that supply things to single organism cells?
- diffusion
- osmosis
- active transport
- endocytosis
- exocytosis
why cant diffusion transport the substances into and out of the inner core of the body in bigger organisms?
the distances between the cells and the outside of the body gets greater as the organism increases in size so diffusion would be too slow and the organism would not survive
what features in common do most circulatory systems have?
- a liquid transport medium that circulates around the system (blood)
- vessels that carry the transport medium
- a pumping mechanism to move the fluid around the system
what is a mass transport system?
when substances are transported in a mass of fluid with a mechanism for moving the fluid around the body
what is a haemocoel?
the open body cavity that the transport medium is pumped into from the heart
what type of pressure is the transport medium under in the haemocoel?
low pressure
how does the transport medium return to the heart in an open circulatory system?
through an open ended vessel
where are open-ended circulatory systems usually found?
in invertebrate animals
what is insects blood called?
haemolymph
what does haemolymph not carry?
oxygen and carbon dioxide
what does haemolymph transport?
food, nitrogenous waste product and the cells involved in defence against disease
what is a closed circulatory system?
when the blood is enclosed in blood vessels and does not come into contact with the cells of the body
how do substances enter and leave the blood in a closed circulatory system?
by diffusion through the walls of the blood vessels
how can blood that is flowing to a particular tissue be adjusted?
by the widening or narrowing of blood vessels
what does blood pigment carry?
respiratory gases
what are the types of closed circulatory systems?
single and double closed circulatory system
where are single closed circulatory systems found?
a number of groups including fish and annelid worms
what is the path blood takes in a single closed circulatory system?
the blood flows through the heart and is pumped out to travel all round the body before returning to the heart
how many capillaries does blood pass through in a single closed circulatory system?
two sets
what occurs in the first set of capillaries in a single closed circulatory system?
it exchanges oxygen and carbon dioxide
what occurs in the second set of capillaries in a single closed circulatory system?
substances are exchanged between the blood and the cells
what happens as a result of blood passing through the two sets of capillaries in a single closed circulatory system?
the blood pressure in the system drops considerably so the blood returns to the heart quite slowly
what is the most important system in transporting substances around the body?
the double closed circulatory system
what are the two circulations the blood goes through in a double closed circulatory system?
- blood is pumped from the heart to the lungs to pick up oxygen and unload CO2, and then returns to the heart
- blood flows through the heart and is pumped out to travel all around the body before returning to the heart again
how many capillary networks does the blood pass through in each circuit in the double closed circulatory system?
one capillary network
what happens because of the blood only passing through one capillary network in the double closed circulatory system?
means a relatively high blood pressure and fast flow can be maintained
what are some examples of different components utilised in some blood vessels?
- elastin fibres
- smooth muscle
- collagen
how are elastin fibres utilised in blood vessels?
composed of elastin and can stretch and recoil, providing vessel walls with flexibility
how is smoot muscle utilised in blood vessels?
contracts and relaxes which changes the size of the lumens
how is collagen utilised in blood vessels?
provides structural support to maintain shape and volume of the vessel
which way do arteries carry bood?
away from the heart to the tissues of the body
what type of blood do arteries carry?
oxygenated blood, except in the pulmonary artery which carries deoxygenated blood from the heart to the lungs
do the arteries have high or low pressure
high
what do artery walls contain?
elastin fibres, smooth muscle and collagen
what do arterioles do?
link the arteries and capillaries
what happens when the smooth muscle in the arteriole contracts and what is the proper name for it ?
it constricts the vessel ad prevents blood flowing into a capillary bed which is called vasoconstriction
what are capillaries?
microscopic blood vessels that link the arterioles with the venules
what type of blood enters the capillaries from the arterioles?
oxygenated
what are some ways in which the capillary has adapted to its role?
- provide a large SA for diffusion
- walls are a single endothelial cell thick, giving a very thin layer of diffusion
- the total cross-sectional area of the capillaries is always greater than the arteriole supplying them so the rate of blood flow falls
which direction do veins carry blood?
away from the cells of the body towards the heart and carry deoxygenated blood, except the pulmonary vein
what does blood travel through to get from capillaries to large veins?
capillaries –> venules –> large veins
why do veins not have a pulse?
the surges from the heart pumping are lost as the blood passes through narrow capillaries
what kind of pressure do veins have?
very low
what do the walls of veins contain?
lots of collagen and relatively little elastin fibres
what do venules link?
capillaries with veins
what are some adaptions that allow blood to be pumped back to the heart against gravity in veins?
- most veins have one way valves at intervals which prevents the backflow of blood
- many bigger veins run in between big muscles so when the muscles contract, it squeezes the blood towards the heart
- breathing movements of chest act as a pump. the pressure changes and squeezing action move blood in the veins of the chest and abdomen towards the heart
what are the three transport mediums in a human?
- blood
- tissue fluid
- lymph
what does plasma carry?
dissolved glucose and amino acids, mineral ions, hormones, RBC’s, WBC’s, platelets and a large amount of plasma proteins, including albumin, fibrinogen and globulins
what is albumin important for in blood?
maintaining osmotic potential of blood
what is fibrinogen important for in blood?
for blood clotting
what are globulins involved in?
transport and the immune system
what do RBC’’s carry?
oxygen to the cells and also gives blood its red appearance
what are platelets?
fragments of large cells called megakaryocytes found in the bone marrow, and they are involved in the clotting mechanism of the blood
what does the blood transport?
- O2 to and CO2 from respiring cells
- digested food from the small intestines
- nitrogenous waste products from the cells to the excretory organs
- hormones
- food molecules from storage compounds to the cells that need them
- platelets to damaged areas
- cells and antibodies involved in the immune response
where can the dissolved plasma pass through?
the fenestrations in the capillary wall, with the exceptions of the large plasma proteins
how do plasma proteins have an osmotic effect?
they give the blood in the capillaries a relatively high solute potential compared to the surrounding fluid
what is oncotic pressure?
the tendency of water to move into the blood by osmosis
what does tissue fluid have the same composition as?
plasma, except the RBC’s and plasma proteins
what does lymph have a similar composition to?
plasma and tissue fluid but has less O2 and fewer nutrients
what else does lymph contain and where does it come from?
also contains fatty acids, which have been absorbed into the lymph from the villi of the small intestine
what do lymph capillaries join up to form?
larger vessels
where do lymphocytes build up and what do they do?
- build up in the lymph nodes when necessary and produce antibodies, which are then passed into the blood
- they also intercept bacteria and other debris from the lymph, which are ingested by phagocytes found in the nodes
what are some adaptations of erythrocytes?
- have a biconcave shape , which has a larger SA than a simple disc structure and so increases the SA available for gas exchange
- mature erythrocytes lose their nuclei, which maximises the amount of haemoglobin that fits into the cells
what is haemoglobin?
a very large globular conjugated protein made up of four peptide chains, each with an iron-containing haem prosthetic group
what is the rection for oxyhaemoglobin?
Hb + 4O2 <==> Hb(O2)4
which side does deoxygenated blood flow in the heart?
flows into the right side of the heart, which pumps it to the lungs
which side does oxygenated blood flow in the heart?
returns from the lungs to the left side of the heart, which pumps it to the body
what is the heart made of?
cardiac muscle, which contracts and relaxes in a regular rhythm
It does not get ________ or need to rest like a __________ muscle?
- fatigued
- skeletal
what do the coronary arteries supply the cardiac muscle with?
the oxygenated blood it needs to keep contracting and relaxing all the time
what is the heart surrounded by?
inelastic pericardial membranes, which help the heart from over-distending with blood
which side of the heart is the wall thicker and why?
- left
- the lungs are relatively close to the heart, so the right side has to pump blood a short distance, whereas the right side has to have enough force to overcome the resistance of the aorta and also pump blood all the way round the body
what is the cardiac cycle?
describes the events in a single heartbeat, which lasts about 8 seconds in a human adult
what happens in diastole?
- the heart relaxes
- the atria and then the ventricles fill with blood
- the volume and pressure of the blood in the heart build as the heart fills, but the pressure in the arteries is at a minimum
what happens in systole?
- the atria contracts, closely followed by the ventricles
- the pressure in the heart increases a lot and blood is forced out the right side of the heart to the lungs and from the left side of the heart to the body
- the volume and pressure of blood in the heart are low at the end of systole, and the blood pressure in the arteries is at a maximum
what makes the sound of a heartbeat?
- the first sound comes as the blood is forced against the atrio-ventricular valves as the ventricles contract
- the second sound comes as a backflow of blood closes the semi-lunar valves in the aorta and pulmonary artery as the ventricles relax
why are cardiac muscles myogenic?
it has its own intrinsic rhythm at around 80 bpm
what is the basic rhythm of the heart maintained by?
a wave of electrical excitation, rather like nerve impulses
where does a wave of electrical excitation begin and what does it cause?
begins in the pacemaker called the Sino-atrial node (SAN), causing the atria to contract and so initiating the heartbeat
what prevents the electrical excitation from passing directly into the ventricles?
a layer of non-conducting tissue
where is the electrical activity from the SAN picked up by?
the atrio-ventricular node (AVN)
what does the AVN do?
imposes a slight delay before stimulating the bundle of His, which penetrate through the septum between ventricles
what is the bundle of His?
a bundle of conducting tissues made up of fibres
what does the bundle of His split in to and what does it conduct?
splits into two branches and conducts the wave of excitation to the apex of the heart
what fibres spread out at the apex of the heart?
the Purkyne fibres spread through the walls of the ventricles on both sides
what does the spread of excitation trigger?
the contraction of the ventricles, starting at the apex
what does contraction starting at the apex allow?
allows more efficient emptying of the ventricles
what makes sure that the atria stops contracting before the ventricles start?
the way in which the wave of excitation spreads through the heart from the SAN with AVN delay
what is an electrocardiogram (ECG)?
the recording of the electrical activity of the heart
what does an ECG measure?
tiny electrical differences in your skin, which result from the electrical activity of the heart
how does the ECG pick up the tiny changes in the skin?
electrodes are stuck painlessly to clean skin to get the good contacts needed for reliable results
what are ECG’s used for?
to help diagnose heart problems
what occurs when a tachycardia ECG is shown?
when the heartbeat is very rapid, over 100bpm
when is a tachycardia heartbeat normal?
when you are exercising, have a fever, if you are scared or angry
what occurs when a bradycardia ECG is shown?
when the heartrate slows down to below 60 bpm
why do many people have bradycardia?
because they are physically fit- training makes the heart beat more slowly and efficiently
what might someone need if they have severe bradycardia and why do they need it?
may need an artificial pacemaker as it keeps the heart beating steadily
what occurs in a ectopic heartbeat?
extra heartbeats that are out of the normal rhythm
how often do most people have an ectopic heartbeat?
at least one per day
what is atrial fibrillation?
an example of arrhythmia, which means an abnormal rhythm of the heart
what happens in the heart when someone has atrial fibrillation
- rapid electrical impulses are generated in the atria
- they contract very fast, up to 400 times a minute
- however they don’t contract properly and only some of the impulses are passed on to the ventricles, which contract much less often
why is an oxygen dissociation curve important?
important for understanding how the blood carries and releases oxygen
what do oxygen dissociation curves show?
the affinity of haemoglobin for oxygen
why does a very small change in the partial pressure of oxygen in the surroundings make a significant difference to the saturation of the haemoglobin with oxygen?
because once the first molecules become attached, the change in the shape of the haemoglobin molecule means other oxygen molecules are added rapidly
why does the curve level out at the highest partial pressures of oxygen on an oxygen dissociation curve?
because all the haem groups are bound to oxygen and so the haemoglobin is saturated and cannot take up anymore
what is the Bohr effect?
when the partial pressure of carbon dioxide rises, therefore the haemoglobin gives up oxygen more easily
the Bohr effect is important in the body because as a result….?
- in active tissues with a high partial pressure of carbon dioxide, haemoglobin gives up its oxygen more easily
- in the lungs where the proportion of carbon dioxide in the air is relatively low, oxygen binds to the haemoglobin molecules easily
what are the ways CO2 is transported from tissues to the lungs?
- about 5% is carried dissolved in the plasma
- 10-20% is combined with the amino acid groups in the polypeptide chains of haemoglobin to form a compound called carbaminohaemoglobin
- 75-85% is converted into hydrogen carbonate ions in the cytoplasm of the RBC’s
