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Biology > Transport in animals > Flashcards

Transport in animals Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

why do multicellular organisms need a transport system?

A

big: they have a low SA:V
higher metabolic rate
active: large number of cells respiring very quickly- in need of rapid supply of glucose and oxygen
carbon dioxide also needs to be removed from cells quickly

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2
Q

what is a single circulatory system?

A

blood only passes through the heart once for each complete circuit of the body e.g. fish pumps blood to gills then through to the rest of the body

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3
Q

what is a double circulatory system?

A

blood passes through the heart twice for each complete circuit of the body- one sends blood to the lungs other sends blood to the rest of the body

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4
Q

what is a closed circulatory system?

A

the blood is enclosed inside blood vessels

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5
Q

what is an open circulatory system?

A

blood vessels all the time flows freely through the body cavity

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6
Q

how does the structure of arteries relate to its function?

A 
thick muscular and elastic tissue than veins - allowed to expand and recoil when the heart beats & maintains blood pressure 
smooth muscle (endothelium) is smooth- allows blood to flow easily over it and it's folded allowing arteries to expand to maintain the high pressure
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7
Q

how does the structure of arterioles relate to its function?

A

more smooth muscle than arteries:
contraction of this muscle layer (vasoconstriction) prevents blood flow into the capillaries
relaxation of this muscle layer (vasodilation) allows blood to flow into the capillaries than arteries because blood pressure is lower

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8
Q

how does the structure of capillaries relate to its function?

A

thin layer of cells (endothelium)- allows for efficient gas exchange
numerous and highly branched- glucose and oxygen can be exchanged
narrow diameter
narrow lumen
spaces between cells

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9
Q

how does the structure veins relate to its function?

A

have valves- prevents backflow as blood pressure is low
large lumen compared to arteries- a lot of blood in your veins
Thin- less elastic and muscular layers compared to arteries no need for thick water pressure is low

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10
Q

what is tissue fluid?

A

containing water glucose amino acid fatty acid ions and oxygen which bathes the tissue

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11
Q

how is tissue fluid formed?

A

capillaries have small gaps in the walls so that liquid and small molecules can be forced out
as blood enters the capillaries from arterioles, the smaller diameter results in high hydrostatic pressure so metabolic waste can be forced out (ultrafiltration)

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12
Q

how is tissue fluid reabsorbed?

A

large molecules remain in the capillaries and therefore creates a lower water potential
towards the venule end of the capillaries, the hydrostatic pressure is lowered due to the loss of liquid, but the water potential is very low
Water re-enters the capillaries by osmosis

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13
Q

what is lymph?

A

not all liquid all be reabsorbed by osmosis- the rest of tissue fluid is absorbed into the lymphatic system
it eventually drains back into the bloodstream near the heart

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14
Q

what are the heart valves and what do they do?

A

atrioventricular valve link the atria to the ventricles
semilunar valves link the ventricles to the pulmonary artery and aorta
they ALL stop blood flowing the wrong way- the valves only open one way
if there’s a higher blood pressure behind a valve it’s forced open
if pressure is higher in front of the valve it’s forced shut
flow of blood is unidirectional (one direction)

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15
Q

what happens during diastole in the cardiac cycle?

A

the atria and ventricular muscles are relaxed
the blood will enter the atria via the vena cava and pulmonary vein
the blood flowing into the atria increases the pressure within the atria

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16
Q

what happens during the atrial systole in the cardiac cycle?

A

the atria muscular walls contract, increasing the pressure further
this causes the atrioventricular valves to open and blood to flow into the ventricles

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17
Q

what happens during ventricular systole in the cardiac cycle?

A

the ventricle muscular walls contract, increasing the pressure beyond that of the atria
this causes the atrioventricular valve to close and the semi-lunar valves to open
the blood is pushed out of the ventricles into the arteries

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18
Q

what is the cardiac output and how do you calculate it?

A

the volume of the blood which leaves one ventricle in 1-minute
cardiac output = heart rate x stroke volume

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19
Q

define myogenic

A

can contract and relax without nervous or hormonal stimulation

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20
Q

what does the left ventricle do?

A

pumps blood to the body
needs to be at higher pressure to ensure blood reaches all cells
much thicker muscular wall to enable large contractions of the muscle to create higher pressure

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21
Q

what does the right ventricle do?

A

pump blood to the lungs
needs to be at lower pressure to prevent damage to capillaries in the lungs
blood flows slowly to allow time for gas exchange

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22
Q

what does the vena cava do?

A

carries deoxygenated blood from from the body into the right atrium

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23
Q

what does the pulmonary vein do?

A

carries oxygenated blood from the lungs to the left atrium

24
Q

what does the pulmonary artery do?

A

carries blood from the right ventricle to the lungs to become oxygenated

25
Q

what does the aorta do?

A

carries oxygenated blood from the left ventricle to the rest of the body

26
Q

what do coronary arteries do?

A

supply the cardiac muscle with oxygenated blood- they branch off from the aorta

27
Q

what is the sinoatrial node?

A

located in the right atrium and is known as the natural pacemaker
initiates electrical impulses to start atrial systole contracts

28
Q

what is the atrioventricular node?

A

located near the border of the right and left ventricle within the atria
responsible for passing the waves of electrical activity on to the bundle of His

29
Q

what is the bundle of His?

A

runs through the septum

transmits impulses from the AVN to the apex

30
Q

what are purkyne fibres?

A

located in the walls of the ventricles

carries the wave of electrical activity onto the muscular walls of right and left ventricle

31
Q

describe the steps in control of heart contractions

A

SAN will release a wave of depolarization across the atria causing it to contract
AVN will release another wave of depolarization when the first wave reaches it
there is a short delay before this happens, this allows enough time for atria to pump all the blood to the ventricles
a band of non-conducting collagen tissue prevents the waves of electrical activity from being passed directly from the atria to the ventricles
instead the bundle of His, running through the septum, can conduct and pass the wave of electrical activity down the septum and the purkyne fibres in the walls of the ventricles
the apex and then walls of the ventricles contract
the cells repolarises and cardiac muscle relaxes

32
Q

what are electrocardiographs used for?

A

a doctor can check someone’s heart function using ECGs
It records the electrical activity of the heart
the heart depolarizes when it contracts and re polarizers when it relaxes
an ECG records these changes in electrical charge using electrodes

33
Q

what are the different waves in ECGs and what do they mean?

A

P wave- is caused by a contraction of the atria
QRS complex- the main peak along with the dips at either side. caused by contraction of ventricles
T wave- is due to relaxation of ventricles
the height of the wave indicates how much electrical charge is passing through the heart
a bigger wave means more electrical charge

34
Q

what is tachycardia?

A

when the heartbeat is too fast- around 120 beats per minute

it’s ok at exercise but at rest it shows that the heart isn’t pumping blood efficiently

35
Q

what is bradycardia?

A

the heartbeat is too slow- 50 beats per minute

36
Q

what is an ectopic heartbeat?

A

an extra heartbeat that interrupts the regular rhythm
it can be caused by early contractions of the ventricles or the atria
occasional ectopic heartbeats in a healthy person don’t cause a problem

37
Q

what is fibrillation?

A

it is a really irregular heartbeat
the atria or ventricles completely lose their rhythm and stop contracting properly
it can result in anything from chest pain and fainting to lack of pulse and death

38
Q

what is the structure of haemoglobin?

A

large, conjugated, globular protein
has 4 subunits in its quaternary structure (2 alpha and 2 beta)
each subunit has one haem group (Fe) and each haem group binds to oxygen molecule

39
Q

how is oxyhaemoglobin formed?

A

in the lungs, oxygen joins to the iron in haemoglobin to form oxyhaemoglobin Hb(O2)4
this is a reversible reaction- near the body cells, oxygen leaves oxyhaemoglobin and it turns back to haemoglobin

40
Q

what is the equation for the association and dissociation of oxyhaemoglobin?

A

Hb + 4O2 ⇌ HbO8

41
Q

define affinity of haemoglobin for oxygen

A

the ability of haemoglobin to attract or bind to oxygen

42
Q

define saturation of haemoglobin with oxygen

A

when haemoglobin is holding the maximum amount of oxygen it can bind to

43
Q

define loading/association of haemoglobin

A

the binding of oxygen to haemoglobin

44
Q

define unloading/association of haemoglobin

A

when oxygen detaches or unbinds from haemoglobin

45
Q

how does oxygen show positive cooperativity?

A

binding of the first oxygen to the haem group changes the shape of the haemoglobin
this increases haemoglobin’s affinity for oxygen

46
Q

what is partial pressure of oxygen (PO2)?

A

it’s a measure of oxygen concentration
the greater the concentration of dissolved oxygen in cells, the higher the partial pressure
as CO2 increases, haemoglobin’s affinity for oxygen also increases

47
Q

when does oxygen load and unload onto haemoglobin?

A

oxygen is loaded in regions with a high partial pressure of oxygen (e.g. alveoli) and is unloaded in regions of low partial pressure of oxygen (e.g. respiring tissue)
this is shown on the oxyhemoglobin dissociation Curve

48
Q

how does saturation of haemoglobin affect the affinity?

A

when haemoglobin combines with the first O2 molecule, it’s shaped alters in a way that makes it easier for other molecules to join too
as haemoglobin starts to become saturated, it is harder for more oxygen molecules to join
as a result the curve is ‘s-shaped’

49
Q

why do adult and fetal haemoglobin have different affinities for oxygen?

A

fetus Hb and has a higher affinity for oxygen than adult haemoglobin
by the time the mother’s blood reaches the placenta, it’s oxygen saturation has decreased because some has been used up by the mother’s body
it has a low PO2 so adult oxyhaemoglobin will unload it’s oxygen
fetuses have to have a higher affinity for oxygen than adult haemoglobin at a lower partial pressure of oxygen.

50
Q

what is the partial pressure of carbon dioxide?

A

it is a measure of concentration of CO2 in a cell

51
Q

how does PCO2 affect the unloading of oxygen?

A

haemoglobin gives up it’s oxygen more readily at a higher PCO2
you get more oxygen to cells during activity
when cells respire, they produce carbon dioxide which raises the PCO2
this increases the rate of oxygen and loading
the dissociation curve shift to the right
saturation of blood with oxygen is lower for a given PCO2, meaning more oxygen is being released

52
Q

what is the Bohr effect?

A

when a high carbon dioxide concentration causes the oxyhaemoglobin curve to shift to the right
affinity for oxygen decreases because carbon dioxide changes the shape of haemoglobin slightly

53
Q

when would the curve shift to the left?

A

at a low partial pressure of carbon dioxide (alveoli)

curve shifts to the left, increased affinity and therefore loads more oxygen

54
Q

when would the curve shift to the right?

A

high partial pressure of carbon dioxide at respiring tissues
curve shift to the right, decreases the affinity and therefore unloads oxygen

55
Q

how does carbon dioxide get transported in the bloodstream?

A

cells respire which produces carbon dioxide
it reacts with water to form carbonic acid catalysed by the enzyme carbonic anhydrase
the rest of the CO2 bind directly to haemoglobin the carbonic acid dissociates to give H+ ions and hydrogen carbonate ions (HCO3-)
increase in H+ ions causes oxyhaemoglobin to unload its oxygen so that haemoglobin can take up H+ ions
this forms haemoglobinic acid
the HCO3- ions diffuse out of the RBC and are transported in the blood plasma

56
Q

what is the chloride shift?

A

to compensate for the loss of HCO3- ions from the red blood cells, chloride ions (Cl-) diffuse into the RBC
this is called the chloride shift- maintains the balance of charge between RBC and plasma
when blood reaches the lungs, the low PCO2 causes some of the HCO3- ions and H+ ions to recombine into CO2 in water
the CO2 then diffuses into the alveoli and is breathed out

Biology (13 decks)

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