3.1.2 Transport in animals Flashcards
1
Q
why is there a need for specialised transport systems in multicellular animals
A
- metabolic demands are high - need lots of O2 + food + waste removal
- small SA:V - diffusion distance larger + not sufficient
- size - large organisms have lager diffusion pathway, diffusion rate reduced + too slow to supply cells
2
Q
why are transport systems necessary
A
- supply oxygen + nutrients
- remove waste products
- temperature maintenance (mammals + birds)
- hormone circulation
3
Q
what are some features of a good circulatory system
A
- liquid transport medium circulating around the system (blood)
- contractile pumping mechanism to move fluid around system
- vessels to carry transport medium
- exchange surfaces to enable substances to enter/leave blood
4
Q
what is a mass transport system
A
- when substances are transported in a mass of fluid around the body
5
Q
what is mass flow
A
- the bulk transport of materials from one point to another as a result of pressure difference between two points
6
Q
describe the features of an open circulatory system
A
- few vessels to contain transport medium
- pumped straight from heart into the body cavity of animal (haemocoel)
> in haemocoel transport medium at low pressure - has direct contact with tissue and cells
> site of exchange between transport medium and cells - transport medium returns to heart through an open-ended vessel
7
Q
where are open circulatory systems mostly found
A
- in invertebrate animals
> mostly insects and molluscs
8
Q
describe the movement of transport medium in an insects open circulatory system
A
- haemolymph (blood) transports food, waste and cells involved in defence against disease
- haemolymph mixes with tissue fluid
- insects have tubular heart + blood travels there and is pumped at low pressure into haemocoel
9
Q
describe the features of a closed circulatory system
A
- blood enclosed in blood vessels
- heart pumps blood at high pressure + quick and returns back to heart
- blood travels ala around system when needed
10
Q
why can insects have open circulatory system but not animals
A
- insects have low metabolic activity + large SA:V ratio
> so lower rate of transportation is sufficient - humans require more pressure + high metabolic activity to require faster blood transportation
11
Q
how do muscles support transport in insects + humans
A
- in insects the muscles contract whilst flying to generate blood flow
- in humans, muscle contract to help blood be pushed up the veins
> heart contracts as well to help blood flow
12
Q
why don’t insects have lungs
A
- gases transported directly to tissues by system of tubes called trachea
13
Q
how does blood flow in single circulatory system
A
- blood flows through heart and pumped out to travel all around the body before returning to heart
14
Q
why is a single closed circulatory system less efficient
A
- blood passes through 2 sets of capillaries
> 1: exchange O2 and Co2
> 2: substances exchanged between blood and cells - blood pressure drops as result of travelling in 2 narrow vessels
> blood returns to heart slowly - good for less metabolically active animals
15
Q
how does blood flow in a double closed circulatory system
A
- blood pumped from heart to lungs (pick up O2 + drop CO2) + returns to heart
- blood flows through heart + pumped out all around the body
16
Q
what are the advantages of a double circulatory system
A
- high pressure of blood
- fast blood flow
- good for metabolically active organisms
17
Q
what is the function of elastic fibres in blood vessels
A
- composed of elastin
- can stretch and recoil, providing vessel wall with flexibility
18
Q
what is the function of smooth muscle in blood vessels
A
- contracts or relaxes which changes size of lumen
19
Q
what is the function of collagen in blood vessels
A
- provides structural support to maintain shape and volume of vessel
20
Q
describe features of arteries
A
- thick muscular and elastic walls
- thick outer layer of collagen
- small lumen
- have a pulse (blood vessel slightly swelling as blood travels through)
- high pressure
- smooth endothelium so blood flows smoothly
21
Q
describe the functions of arteries
A
- carry blood away from the heart
> oxygenated (except pulmonary)
22
Q
what is the function of elastic fibres in arteries
A
- enable them to withstand the force of blood pumped at high pressure
> allows for stretch and recoil - regulates fluctuations in blood flow
23
Q
what are arterioles + structure / function
A
- arterioles link arteries and capillaries
- have more smooth muscle + less elastin than arteries
> less pulse surge + constrict / dilate to control blood flow
24
Q
what is vasoconstriction
A
- smooth muscle in arteriole contracts
- this constricts the vessel and prevents blood flowing into capillary bed
25
what is vasodilation
- smooth muscle in arteriole relaxes
- blood flows through into the capillary bed
26
describe features of capillaries
- one cell thick
- very small lumen
- epithelial cell wall only
- large SA:V
- permeable walls
- large total cross-section area
27
why is the large total cross-sectional area for capillaries aa good feature
- rate of blood flow falls
> slow movement of blood through capillaries gives more time for exchange of materials by diffusion between blood and cells
28
why do rough epithelial cells in capillaries provide as a good feature
- friction
> slows blood down
29
describe features of veins
- thin collagen + elastin (strength)
- wide lumen
- low pressure
- no pulse
- valves
30
describe the functions of veins
- carry blood to the heart
> deoxygenated (except pulmonary)
31
what are venules + structure / function
- link capillaries with veins
- very thin walls + little smooth muscle
32
what are the 3 layers of the blood vessels
- tunica interna (endothelial cells)
- tunica media (smooth muscle)
- tunica externa (elastin and collagen)
33
what type of circulatory system does an insect have
- single open circulatory system
34
where is location of heart + no of chambers in insects
- found in dorsal vessel (backside of chest)
> many chambers
35
what makes blood flow around insects body
- peristaltic contraction of muscles of the heart
> pulsatile organs
> blood flow is sluggish
36
what type of circulatory system does a fish have
- single closed circulatory system
37
where is the location of the heart + no of chambers in a fish
- near gills
> 2 chambers
38
what makes blood flow around a fish body
- pressure
- contraction of ventricles takes blood to gills
- skeletal pump ensures continuous flow
> blood flow is sluggish
39
what type of circulatory system do mammals have
- double closed circulatory system
40
where is the location of heart + no of chambers in mammals
- near lungs
> 4 chambers
41
what makes blood flow around the mammalian body
- high pressure
- contraction of ventricles
- skeletal muscles
- valves prevent backflow
- respiratory pump
42
what does pulmonary reference to
- the lungs
43
what does coronary / cardiac reference to
- the heart
44
what does hepatic reference to
- the liver
45
what does renal reference to
- the kidneys
46
what type of muscle is the heart made up of + its significance
- cardiac muscle which is myogenic
> requires no nervous impulse from brain to contract so can create it's own electrical impulse (due to pacemaker cells) so can contract
47
why is backflow of blood bad
- reduced volume of blood travelling through arteries (reduced pressure)
- worse circulation of blood around body
- less oxygen sent to respiring tissues
> respiring tissues unable to function due to lack of aerobic respiration causing fatigue/weakness
48
what side of the heart does oxygenated/deoxygenated blood flow to
- deoxygenated blood flows to right side then lungs
- oxygenated blood flows to left side then body
49
what are the two types of valves in the heart and where are they found
- atrioventricular valves are found between atrium + ventricles
> bicuspid valve in left
> tricuspid in right
- semi-lunar valves found between arteries + ventricles
50
what is the role of coronary arteries in the heart
- supplies cardiac muscle with oxygenated blood it needs to keep contracting + relaxing all the time
51
what is the septum + function
- inner dividing wall of the heart
> prevents mixing of deoxygenated + oxygenated blood
52
what is the cardiac cycle
- the sequence of events in one heartbeat
53
name the 3 phases of the cardiac cycle
- diastole
- atrial systole
- ventricular systole
54
describe what happens in diastole
- heart relaxes (atria + ventricles)
- blood flows into atria from veins
- av + semi-lunar valves closes
- pressure in atria slowly increases
55
describe what happens in atrial systole
- pressure higher in atria than ventricles + pressure in atria increases
- atria contract (atrial wall contract)
- av valves open + sl close
- blood moves from atria to ventricles through av valves
56
describe what happens in ventricular systole
- pressure in ventricles increases
- ventricular walls contract
> this builds pressure up to the point the av valves close
- pressure eventually opens up sl valves
- blood moves out of ventricles into arteries through sl valves
57
what is the sound of a heartbeat described as
- lub-dub
> sound made by valves closing
58
how is the lub-dub heartbeat sound made
- lub: made by av valves closing as ventricles start to contract
- dub: made by sl valves closing as ventricles start to relax
59
what is stroke volume
- volume of blood pumped by heart in one cardiac cycle
> increases during excercise
60
what is cardiac output + how is it calculated
- Cardiac output is the volume of blood pumped in one minute
> CO = stroke volume x heart rate
> litres of blood per minute
61
What factors affect heart rate
- adrenaline
- movement of limbs
- levels of respiratory gases in blood
> high O2 = low heart rate
> high CO2 = high heart rate
- blood pressure - if too high then safety mechanism prevents further increase of heart rate
62
how does adrenaline increase heart rate
- adrenaline released into blood (adrenal glands)
- receptors in heart detect adrenaline
> causes pacemaker cells in heart to send impulses more often
> causes increased heart rate
63
describe how initiation and control of the cardiac cycle is achieved
- wave of electrical impulse sent out by sino-atrial node (in wall of right atrium) across both atria, causing them to contract (top to bottom)
- non-conductive tissue prevents excitation passing directly to ventricles
> allows atria time to complete contraction
- atrio-ventricular node picks up impulse
- impulse passed down specialised muscle fibres in septum called bundle of His
- bundle of His carries impulse to apex of ventricles but doesn't cause contractions
- impulse travels back up Purkyne fibres causing ventricles to contract (bottom to top), forcing blood out
64
what do Electrocardiograms (ECGs) do
- monitor the electrical activity of the heart
> measures the electrical differences in your skin which is caused by electrical activity of heart
> picked up through tiny painless electrodes in skin
65
what can an irregular shape of an ECG trace indicate
- problems such as:
> arrhythmia (irregular heartbeat)
> fibrillation (uncoordinated beat)
> heart attack
66
what is bradycardia
- slow heart rate
> too long between each normal heart beat
- common when fit + training
67
what is tachycardia
- fast heart beat
> not too long between each normal heart beat
- when frightened or angry
68
what is an ectopic heart beat
- extra heart beats that are out of the normal rhythm
69
what is atrial fibrillation
- abnormal irregular rhythm from atria
> atria contract too fast
70
what does blood consist of
- plasma (yellow liquid)
> contains dissolved components e.g. glucose, amino acids
- red blood cells
- white blood cells
- platelets (clotting mechanism)
71
what are some things blood transports
- O2 to and CO2 from respiring cells
- digested food from small intestine
- chemical messages (hormones)
- platelets to damaged areas
- cells and antibodies involved in immune response
72
what is tissue fluid
- tissue fluid is formed when blood moves through capillaries and plasma moves into surrounding tissues
> no large plasma proteins as they can't pass through endothelium
- consists of amino acids, glucose, salts, O2 etc
73
what is oncotic pressure
- oncotic pressure is caused by difference in water potential and is the tendency of water to move into the blood by osmosis
> pressure will be from an area of low solute conc to an area of high solute conc
74
what is hydrostatic pressure
- caused by blood moving through blood vessels
74
describe the movement of tissue fluid in capillary
- at arterial end there is higher hydrostatic pressure than oncotic pressure
> blood pressure high + low solute conc
- tissue fluid moves into tissues
- at venule end, the oncotic pressure is higher than hydrostatic pressure
> blood pressure low + solute conc high
- tissue fluid moves back into capillary
75
why does blood have higher hydrostatic pressure than tissue fluid
- blood is being pumped by the heart at high pressures
76
what is lymph
- 10% of tissue fluid enters lymph vessels
> lymph just like tissue fluid but less O2 + nutrients
77
how is lymph moved in the lymph vessels
- movement of muscles, valves and negative pressure in chest cause lymph to move
> moves very slowly towards heart
78
what are lymph nodes
- formed along lymphatic system
- contain lymphocytes that create white blood cells to fight against antigens
79
how does fluid leave lymph
- through subclavian veins found under collarbones
> milky in colour as it contains lipids
80
what are some adaptations of erythrocytes (red blood cells) in transportation of gases
- lacks nucleus: more space for Hb + more O2 loaded
- biconcave disc: large SA:V so faster exchange of gases
- Hb: carry O2
- diameter just fits capillary lumen: entire surface in contact with capillary wall so more area for exchange
81
what is haemoglobin made up of
- 4 haem groups + 4 polypeptide chains
> 2 alpha glucose + 2 beta pleated sheets
- can hold up to 4 O2 molecules
82
as the partial pressure of O2 is high what happens to saturation in hemoglobin
- at high partial pressures of O2 (and medium), haemoglobin is highly saturated
> it favours the loading of O2 in the lungs
83
as the partial pressure of O2 decreases what happens to saturation in haemoglobin
- small drop in O2 partial pressure leads to rapid decrease in % saturation of haemoglobin
> it favours the release of O2 in tissue cells
84
what is the affinity of haemoglobin to Oxygen like
- high affinity for O2 in environment (loading)
> unloads it easily to tissue cells where O2 levels are low
85
what are the formulas for haemoglobin loading and unloading oxygen
- loading: Hb + 4O2 ----> Hb(O2)4
- unloading: Hb(O2)4 ----> Hb + 4O2
86
what forms when haemoglobin binds to oxygen
- oxyhaemoglobin
87
why is the oxygen dissociation curve non-linear
- at medium partial pressures of O2, oxyhaemoglobin unloads very little oxygen until it reaches body tissue
88
why do some animals load at medium partial pressures of O2
- haemoglobin is adapted to become fully saturated at lower levels of O2
> e.g. if they live in environment with less oxygen
89
why do some animals unload at very little O2 partial pressures
- trying to conserve O2
90
humans load + unload at
- load very high O2 partial pressures
- unload at very low
91
small birds load + unload at
- load at very high O2 partial pressures
- unloads at medium partial pressures
> cells highly metabolically active so need O2 supplied more often + quicker
> for respiration
92
describe the differences between the dissociation curve between fetal + maternal haemoglobin
- fetal Hb loads at lower partial pressures (placenta has lower partial pressure O2)
- maternal loads in lungs at high partial pressures O2
> at placenta maternal unloads while fetal loads
93
what is function of myoglobin
- stores O2 in muscles + releases it when O2 partial pressure is very low
- acts as a reserve ad is usually loading O2 when at rest (whole Hb unloads)
94
describe the differences between the dissociation curves for myoglobin + haemoglobin
- haemoglobin has higher affinity than myoglobin at high partial pressures of O2 and so loads a lot of oxygen
- at medium partial pressures, myoglobin has higher affinity than haemoglobin so whilst Hb unloads, myoglobin loads
95
why can't Co2 be left to accumulate in the blood
- the acid from it can lead to fatal changes in pH
96
what are the 3 ways CO2 can be transported form the tissue to lungs
- dissolved in plasma (5%)
- combined with haemoglobin (10-20%)
> combines with amino groups to form carbaminohaemoglobin
- as hydrogen carbonate in cytoplasm of RBC (75-85%)
97
describe the steps in how haemoglobinic acid is made in the blood
1. cell respires to produce CO2 which moves out of body cell to RBC
2. CO2 combines with H2O to form H2CO3 (carbonic acid) - catalysed by carbonic anhydrase
3. Carbonic acid (weak) partially dissociates to form H+ and HCO3-
4. Oxyhaemoglobin unloads oxygen to get haemoglobin: Hb(O2)4 ---> Hb + 4O2
5. Hb combines with H+ to form haemoglobinic acid
98
describe what happens to the hydrogen carbonate (HCO3) in the tissues
- HCO3 moves out of RBC into plasma
- to counter act chloride ions move in (chloride shift)
- HCO3 combines with Na to form NaHCO3
99
describe what happens to hydrogen carbonate in lungs
- hydrogen carbonate moves back into RBC (Chloride moves out)
- react with H+ to form Carbonic acid
- carbonic acid broken down by carbonic anhydrase
> releases CO2
- CO2 diffuse out of RBC into lungs
100
why does Hb combines with H+
- H+ is an acid so can lower pH of blood cell
- Hb combines with H+ to create haemoglobinic acid
> acts as a pH buffer to prevent pH getting low
101
where does the oxygen go after oxyhaemoglobin unloads it to form haemoglobinic acid
- Oxygen goes to respiring tissues
> this is useful as it provides O2 to tissues that are producing more Co2 carrying out respiration
102
what happens to the dissociation curve as you increase CO2 levels
- curve shifts to the right
> haemoglobin has lower affinity to O2 as it unloads it for respiring tissue (aerobic respiration)
> more Hb needed for CO2 removal
103
what is the Bohr effect
- as partial pressures of CO2 rises, haemoglobin unloads oxygen more easily
104
Why is the Bohr effect important / benefits
- in active tissues with high partial pressures of CO2, haemoglobin unloads oxygen more readily
> releases more O2 for aerobic respiration
- in lungs where proportion of CO2 in air is relatively low, O2 binds to haemoglobin easily
