Transport in Animals

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What type of organisms have an open circulatory system?
most insects, some molluscs and arthropods
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How does oxygen diffuse into cells of organisms with an open circulatory system?
The blood bathes the tissues directly.
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What is insect blood called?
hemolymph
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Why is a double circulatory system able to supply a fast rate of delivery of oxygen and nutrients?
The blood gets repressurised at the heart so is pumped to the body cells at a higher pressure.
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Why do fish only need a single circulatory system?
1) their countercurrent gaseous exchange mechanism means they are able to take in lots of O2, their body weight is supported by the water, they don't maintain their body temp (reducing metabolic demands)
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What is the function of the tunica interna/ endothelium?
Reduces friction of the blood against the vessel wall
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What are feeling when we feel our pulse?
The flexing of the arterial wall, allowed by the tunica media/ smooth muscle and elastic tissue
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What are fenestrations?
Gaps between a single layer of epithelial cells.
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How does an arteriole differ from an artery?
They have less elastic tissue and more smooth muscle- to constrict blood flow to the capillaries
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What is the composition and function of the connective tissue/ tunica externa?
Consists mainly of collagen fibres which provide strength and durability
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In what ways do the structure of veins differ from arteries?
1) larger lumen 2) Thinner tunica media 3) thinner tunica externa
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Which two arteries carry deoxygenated blood?
the pulmonary artery and the umbilical chord artery
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what is the average size of the lumen in a capillary?
10 micrometers
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What is an aneurysm and what have they been linked to?
They are a bulge or weakness in a blood vessel and have been linked to the collagen: elastin ratio. high proportion of collagen compared to elastin the blood vessel is less elastic so is less able to withstand surges of blood in aorta
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why are muscles important in circulation?
When they contract they squeeze veins forcing blood towards the heart
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What percentage of your blood volume is in your veins at any one time?
60%
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What type of circulation is the left atrium involved in?
systematic circulation
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What is the function of the cross bridged fibres (myofibrils) found in cardiac muscle?
they help spread the stimulus around the heart and ensure that the muscles can produce a squeezing action rather than a simple reduction in length
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How do muscle cells achieve synchronised contraction?
They are separated by intercalated discs
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What happens during atrial systole?
the atria contract, the ventricles are relaxed the atrioventricular valves are pushed open and the semilunar valves are closed
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what happens during diastole?
Chambers are relaxed, the semi-lunar valves are pushed closed, the atrio-ventricular valves allow blood to trickle through into the ventricles but are not fully open
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where do the lub-dub sounds of a stethoscope come from?
1st) blood is forced against AV valves as ventricles contract, 2nd) comes as a backflow of blood closes the semilunar valves in the aorta and pulmonary artery as the ventricles relax
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What does myogenic mean?
that the rhythm is intrinsic and comes from the muscle tissue itself rather than from nerve tissue
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what is the function of the AV node.
It allows the wave of depolarisation to spread to the ventricles but it imposes a slight delay in order to ensure that the atria and ventricles do not contract simultaneously.
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where does contraction of the ventricles start and why is this important?
Contraction starts at the apex- this ensures efficient emptying of the ventricles. If they contracted from the top down blood would simply be pushed deeper into the ventricles
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What is an ectopic heart beat?
An extra heart beat that is out of the normal rhythm.
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what does an elevated ST segment indicate?
An impending myocardic infarction (heart attack)
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What is lymph?
A colourless/pale yellow fluid similar to tissue fluid but containing more lipids
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What is tissue fluid?
Blood plasma that has drained out of the capillaries, but without the plasma proteins e.g. albumin- too large to pass through capillary wall
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List three plasma proteins and there functions.
Albumin-important for maintaining osmotic potential in the blood, Fibrogen- important in blood clotting, Globulins-involved in transport and the immune system
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What is oncotic pressure and what is its value in humans?
The tendency of water to move into the blood in the capillaries from the surrounding tissues by osmosis. It is about -3.3kPa
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Filtration pressure=...
...hydrostatic pressure- oncotic pressure
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What is the hydrostatic pressure?
the pressure put on the arterioles and capillaries every time the heart contracts
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What is the partial pressure?
the relative pressure a gas contributes to a mixture of gases.
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What is haemoglobin made up of?
Four polypeptide chains (two alpha and two beta), each bound to one haem group
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Where is myoglobin found?, why?
Found in muscle cells where it acts as an oxygen reserve. It has a very high affinity for oxygen even at very low partial pressures so will only dissociate when oxygen levels are VERY low.
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where is foetal haemoglobin produced?
In the liver
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Why does haemoglobin's affinity for oxygen increase once one oxygen molecule has associated? What is this known as?
The haemoglobin undergoes a conformational change and the polypeptides become more loosely wound allowing O2 molecules to bind more easily. This is known as positive cooperativity.
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Hb+CO2=...
...carbamino haemoglobin
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Hb+ H+ions =...
haemoglobinic acid
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what happens to 85% of the CO2 that diffuses out of respiring tissues
It reacts with H20 in the red blood cell forming carbonic acid (H2CO3) catalysed by carbonic anhydrase. The carbonic acid then releases H+ ions leaving HCO3- ions which diffuse out of the cell
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What is the chloride shift?
The process of Cl- ions moving into the red blood cell to compensate for the HCO3- ions exiting the cell
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Where is the Sino-atrial node situated?
In the wall of the right atrium between the entires of the superior and inferior vena carvae
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What are 'waves of depolarisation'?
waves of electrical excitation.
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What is the bundle of his
The collective name for the left and right ventricular bundles. conducts depolarisation waves form the AV node to the septum
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What is the cardio acceleratory centre?
A continuation of the spinal chord within the skull forming the lowest part of the brainstem containing control centres for the heart and lungs. It increases cardiac output
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What are the papillary muscles?
Mucles on the inside of ventricle walls which attach to the cusps of the AV valves via the chrodae tenineae. They regulate the opening and closing of the valves and prevent them inverting during systole.
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What is the thickest layer of the artery wall? What is this layer made up of?
The tunica media. It is made up of smooth muscle and elastic tissue
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What is the function of the collagen fibres of the tunica Adventitia/ connective tissue?
to provide strength and durability
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Why is the connective tissue in veins much thinner than in arteries?
because the veins don't have to withstand a high pressure
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How does an arteriole differ from an artery?
Aterioles have more smooth muscle and less elastic tissue. This enables them to constrict and reduce the rate of blood flow through the capillaries.
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Why do capillaries form capillary beds?
they allow the blood vessels to be as close to the cells as possible to ensure efficient exchange of substances.
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What is the function of the Endothelium/ tunica intima?
to reduce friction of blood against the vessel wall.
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What is the relative thickness of the tunica intima in each blood vessel?
It is a similar thickness in both veins and arteries.
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Why is haemoglobin described as a conjugated protein?
Because it is a complex protein- it contains a non-prosthetic haeme group (an Fe2+ ion)
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What is the function of elastic tissue in the arteries?
It helps to even out fluctuations in blood pressure created by the heart.
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Each cardiac muscle cell has a nucleus and is divided into units called...?
Sacromeres
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How does haemolymph differ from human blood?
It doesn't carry CO2 or O2
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What types of organisms have a three chambered heart?
Amphibians, reptiles
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Why is a 3 chambered heart less efficient?
Because oxygenated and deoxygenated blood are mixed
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How does increasing the partial pressure of CO2 ensure a greater delivery of oxygen to exercising muscles?
More CO2 means more carbonic acid will form and hence more H+ions will be released. These combine to oxyhaemoglobin and reduce Hb's affinity for O2, meaning haemoglobin releases more O2
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Why is it important that the steepest part of an oxygen dissociation curve is between P(O2) 2 and 5 Kpa
The steepest part corresponds to where organs need most oxygen. A drop in oxygen partial pressure rapidly decreases the oxygen saturation releasing more oxygen to the tissues
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What is a conformational change and why is it important?
A conformational change is a slight change in the shape of a haemoglobin molecule. It is important as it changes the shape of the haemoglobin molecule increasing its affinity for oxygen.
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What effect does increased CO2 concentration, increased acidity, exercise and increased temperature have on the oxygen dissociation curve? why?
It shifts the curve to the right as these are all situations where oxygen demand increases
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Why is it important that foetal haemoglobin has a higher affinity for oxygen than maternal haemoglobin?
- must have a higher affinity for oxygen in order for the maternal haemoglobin to give up its oxygen. The higher affinity is essential for maintaining a diffusion gradient ensuring blood can travel across placenta+ foetus is able to respire
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What is hydrostatic pressure?
The pressure that a fluid exerts when pushing against the sides of a vessel
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What is the oncotic pressure?
The pressure created by the osmotic effects of the solutes. The tendency of of water to move into the blood in the capillaries from the surrounding fluid
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Other cards in this set

Card 2

Front

How does oxygen diffuse into cells of organisms with an open circulatory system?

Back

The blood bathes the tissues directly.

Card 3

Front

What is insect blood called?

Back

Preview of the front of card 3

Card 4

Front

Why is a double circulatory system able to supply a fast rate of delivery of oxygen and nutrients?

Back

Preview of the front of card 4

Card 5

Front

Why do fish only need a single circulatory system?

Back

Preview of the front of card 5
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