3.2 Flashcards
1
Q
what is a closed circulation system?
A
blood travels through blood vessels with the impetus being generated by a muscular pump or heart
2
Q
what is an open circulation system?
A
‘blood’ bathes all the cells and organs of the body
3
Q
what are the technical names for ‘blood’ and others in the process?
A
the blood called haemolymph and is in the body cavity called haemocoel
4
Q
what are facts about closed circulation?
A
delivers blood quickly to tissues under pressure
5
Q
what is single circulation?
A
blood passes through heart once in each circulation
6
Q
what is the heart like in a fish?
A
single circulation. heart has two chambers (atrium and ventricle)
7
Q
what is a disadvantage of single circulation?
A
blood loses pressure around the circuit resulting in slower circulation
8
Q
what is a double circulation system?
A
blood passes through the heart twice in one circulation of the system
9
Q
what is an advantage of a double circulation system?
A
blood is depressurised when it leaves the gas exchange surface giving a faster and more efficient circulation to the tissues
10
Q
what type of circulation system to insects have?
A
open
11
Q
what type of circulation system do earthworms have?
A
closed
12
Q
what type of circulation do mammals have?
A
closed, double
13
Q
why is blood returned to the heart in mammals?
A
blood pressure is reduced in capillaries of lungs and would be too low to reach whole body
14
Q
what is the route of blood in one circulation?
A
1- (superior or inferior) vena cava
2- right atrium
3- tricuspid valve
4- right ventricle
5- pulmonary artery
6- lungs
7- pulmonary vein
8- left atrium
9- bicuspid value
10- left ventricle
11- aorta
12- body
15
Q
what type of blood is on the right side of the heart?
A
deoxygenated
16
Q
what type of blood is on the left side of the heart?
A
oxygenated
17
Q
what are the stages in the cardiac cycle?
A
1- cardiac diastole
2- atrial systole, ventricular diastole
3- atrial diastole, ventricular systole
18
Q
what happens during cardiac diastole?
A
blood at low pressure flows into the atria which increases the pressure, some of blood flows through tri/bicuspid valves and into relaxed ventricles
19
Q
what happens in atrial systole and ventricular diastole?
A
when atria are full their walls contract cause blood to be pushed into ventricles, pressure in atria is increased when it contracts, pressure in ventricles increases as it fills with blood
20
Q
what happens during atrial diastole and ventricular systole?
A
after a short delay the ventricles contract from apex up which increases pressure, due to higher pressure in ventricles than atria the blood pushes back on valves causing them to shut, semi lunar valves open and blood leaves heart, ventricles relax and semi lunar valves shut (blood falls back down a bit due to gravity)
21
Q
what causes the sound of the heart beat?
A
valves closing
22
Q
what are periods of contracting called?
A
systole
23
Q
what are periods of relaxing called?
A
diastole
24
Q
what does one cardiac cycle consist of?
A
atria and ventricles contracting so that the blood that has entered the heart is pumped out
25
how many times a minute does the cardiac cycle occur?
60-80 times every minute
26
what is the structure of blood vessels?
tunica intima, tunica media, tunica externa
27
what is the tunica intima?
single layer of endothelium, smooth lining to reduce friction, some arteries are supported by elastin-rich collagen
28
what is the tunica media,?
contains elastic fibres and smooth muscle
29
how is a pulse felt?
in arteries as elastic fibres recoil and push blood through
30
what does contraction of the muscles do in blood vessels?
regulates blood flow and maintains blood pressure when transported further from heart
31
what is the tunica externa?
contains collagen fibres which resist over stretching
32
how big are arteries?
10mm
33
how big are capillaries?
0.2mm
34
how big are veins?
6mm
35
what is the function of arteries?
carry blood away from heart, thick muscular walls withstand bloods high pressure, branch into arterioles then into capillaries
36
what is the function of capillaries?
vast network that penetrates all tissues and organs, blood from capillaries collect into venues into veins
37
what is the function of veins?
transport blood from body to heart, larger lumen and thinner walls and lower flow rate and blood pressure, veins above heart move by gravity, moves through other veins by pressure from surrounding muscle, have semi-lunar valves to prevent backflow, faulty functioning can contribute to varicose veins and heart failure
38
why are there pores between cells in capillaries?
to be permeable to water and solutes for exchange between tissues and blood
39
why are there many capillaries in a capillary bed?
to decrease blood flow for more time for materials to exchange
40
what type of muscle is in the heart?
cardiac muscle
41
why is the heart myogenic?
its contracting is initiated from within the heart itself and not from nervous stimulation
42
where does the signal for the heart contracting come from?
sinoatrial node
43
describe how heartbeat is controlled
the sinoatrial node starts the wave of depolarisation which results in contraction of atria when the waves spread out over the walls. there is a band of fibres which have electrical resistance so the waves cant spread past here. the atrioventricular node is located in the septum and can conduct so it will pass on the wave of depolarisation after a short gap. the excitation passes down the Bundle of His and to the Purkinje in the inner ventricular septum. it passes to the apex of the heart then through ventricular walls leading to them contracting from the apex up to make sure blood is pushed up and out.
44
what is haemoglobin made of?
4 globular proteins and 1 iron ion in each globular protein
45
what is haemoglobin?
the molecule that allows erythrocytes to carry oxygen and has an affinity for oxygen
46
what does affinity for oxygen mean?
it can carry oxygen molecules
47
what is hameoglobin called when oxygenated?
oxyhaemoglobin
48
what are the adaptations of red blood cells?
biconcave shape to maximise surface area for gas exchange, small and flexible to pass through narrow capillaries, no nucleus for more room to carry respiratory gases, packed with haemoglobin
49
what is the word equation for the reversible reaction of oxygen and haemoglobin?
haemoglobin + oxygen <> oxyhaemoglobin
50
what is the shorthand for haemoglobin?
Hb
51
what is the equation for the reversible reaction between oxygen and haemoglobin?
Hb + 4O2 <> Hb.4O2
52
how is oxygen transported from lungs to respiring tissue?
in the lungs oxygen diffuses into blood plasma and then down a concentration gradient into the erythrocyte. oxygen binds to haemoglobin to maintain concentration gradient. oxygen binds to the Fe2+ group. in respiring tissue the oxygen dissociates from oxyhaemoglobin and then oxygen can diffuse out of erythrocyte and to respiring cells
53
what is 100% saturation?
the haemoglobin is carrying its maximum amount of oxygen
54
what are the units for saturation?
SaO2 %
55
what is the normal saturation of blood leaving the lungs?
95-99%
56
what is concentration of oxygen referred to as? + units
partial pressure for oxygen (pO2) which is measured in kPa
57
why is ventilation important?
to allow lung tissue to have a high pO2
58
what does high pO2 mean?
more oxygen is able to associate with haemoglobin molecules to be transported?
59
where is pO2 highest?
in the lungs
60
describe the oxygen dissociation curve
not directly proportional, s-shaped, very hard to reach 100% saturation
61
describe how it is hard for 100% saturation to occur
after the first oxygen molecule assocaites the haemoglobin conformation changes which makes it easier for the 2nd and 3rd to associate. the haemoglobin ahs become "full" so it is harder for the 4th oxygen molecule to associate (it has changed so much). therefor the curve plateaus before 100%
62
what is the process of oxygen joining haemoglobin called?
co-operative binding
63
what are the ways of carbon dioxide being transported?
dissolved in plasma (5%), associated with Hb to form carbamino-haemoglobin (10%), transported as hydrogen carbonate ions (85%)
64
what is the process of CO2 being transported as hydrogen carbonate ions?
1- CO2 diffuses into RBC
2- CO2 dissolves in water to form carbonic acid (carbonic anhydrase catalyst)
3- carbonic acid dissocaites into H+ and HCO3-
4- HCO3- diffuse out of erythrocyte into plasma via facilitated diffusion
5- to balance outflow of negative charge, Cl- diffuse into the cell to balance the charge (chloride shift)
6- H+ ions cause oxyhaemoglobin to dissocaite and combines with the haemoglobin to form haemoglobonic acid (HHb) which removes the H+ so the pH of the cell doesnt fall
7- oxygen diffuses out of cell into tissues
65
why does H+ cause oxyhaemoglobin to dissocaite?
haemoglobin has a higher affinity for H than O2
66
what happens to oxygen in a CO2 rich environment?
more oxygen dissociates from oxyhaemoglobin
67
what is the Bohr effect?
the oxygen dissocation curve shifting to the right
68
outline the effect of carbon dioxide on haemoglobins affinity for oxygen
at respiring tissues there are low oxygen levels and high carbon dioxide levels due to respiration. At high partial pressures of CO2 more CO2 is diffusing into the erythrocytes. So more carbonic acid is formed which dissociates into hydrogen carbonate ions and hydrogen ions. Hydrogen ions bind more readily to harmoglobin than oxygen. Therefore more oxygen is dissociated. At higher partial pressures of carbon dioxide haemoglobin has a lower affinity for oxygen
69
what is tissue fluid?
blood plasma without plasma proteins, forced through capillary walls to bathe cells and filling the spaces between them.
70
how is tissue fluid made? (leave capillary)
blood is under pressure from the heart which means there is high hydrostatic pressure at the arteriole end so liquid is pushed out of the capillary. Plasma has a low solute potential so water tends to be pulled back into the capillary by osmosis. higher hydrostatic pressure than solute potential so water and solutes are pushed out. Solutes (glucose and oxygen) are used in cell metabolism so there are low concentrations around the cell which favours diffusion from blood to tissue fluid.
71
how does tissue fluid re-enter the capillaries?
bloods hydrostatic pressure is lower as it has lost fluid and friction resists the flow. blood has a high solute potential as lots of water has diffused out. the osmotic force is greater than hydrostatic pressure so water passes into capillaries by osmosis. waste products diffuse into tissue fluid which are brough into blood.
about 10% of tissue fluid doesn't diffuse back into the capillaries and drains into the lymph capillaries. most lymph fluid returns to venous system through thoraric duct and empties into subclavian vein
72
what is the lymph?
fluid absorbed from between cells into lymph capillaries rather than back into capillaries
73
plasma:
1- site
2- associated cells
3- respiratory gases
4- nutrients
5- large protein molecules?
6- water potential
1- blood vessels
2- erythrocytes, granulocytes, lymphocytes
3- more O2, less CO2
4- more
5- yes
6- lower
74
tissue fluid
1- site
2- associated cells
3- respiratory gases
4- nutrients
5- large protein molecules?
6- water potential
1- surrounding body cells
2- granulocytes, lymphocytes
3- less O2, more CO2
4- fewer
5- no
6- higher
75
lymph
1- site
2- associated cells
3- respiratory gases
4- nutrients
5- large protein molecules?
6- water potential
1- lymph capillary vessels
2- granulocytes, lymphocytes
3- less O2 more CO2
4- fewer
5- no
6- higher
76
what does ECG stand for?
electrocardiogram
77
what is an electrocardiogram?
trace of voltage changes produced by the heart, detected by electrodes on the skin
78
what is the p wave?
first part of the trace and shows the voltage change generated by the sino-atrial node associated with the contraction of the atria. the atria have less muscle than ventricles so p waves are small.
79
what is the PR interval?
the time between the start of the p wave and the start of the QRS complex. it is the time taken for the excitation to spread from the atria to the ventricles through the atrio-ventricular node
80
what is the QRS complex?
shows the depolarisation and contraction of the ventricles. ventricles have more muscle than the atria so the amplitude is bigger than the p wave
81
what is the T wave?
it shows the repolarisation of the ventricular muscles
82
what is the ST segment?
it lasts from the end of the S wave to the beginning of the T wave
83
what is the line between T wave and P wave of the next cycle?
isoelectric line- baseline of the trace
84
what would a person with atrial fibrilation's trace show?
rapid heart rate and may lack a p wave
85
what would a person who has had a heart attack trace show?
may have a wide QRS complex
86
what would a person with enlarged ventricle trace show?
may have a QRS complex showing a greater voltage charge
87
what might show someone has blocked coronary arteries and atherosclerosis? (insufficient blood being delivered to heart)
changes in height of the ST segment and T waves
88
how do you calculate heart rate (bpm)?
60 / length of cardia cycle (s)
89
what is vascular tissue?
transports materials around the plant and comprises of the xylem and phloem in vascular bundle
90
what is the structure of the roots?
xylem is central and star shaped with phloem between groups of xylem cells. this arrangement resists vertical stress (pull) and anchors the plant in the soil
91
what is the structure of the stem?
vascular bundles are in a ring at the periphery with xylem towards the centre and phloem towards the outside. this gives flexible support and resists bending
92
what is the layers of the root? (out to in)
root hair cell, epidermis, cortex, endodermis, stele (pericycle, phloem, xylem)
93
what is the layers of the stem? (out to in)
epidermis, collenchyma, vascular bundle (fibres, phloem, xylem), cortex, medulla
94
what is the structure of a leaf?
vascular tissue is in the midrib and in a network of veins, giving flexible strength and resistance to tearing
95
what is the layers of a leaf? (out to in)
abaxial surface, collenchyma, edges: vascular bundle in leaf veins, middle : compacted parenchyma, vascular bundle in midrib (xylem on top, phloem below)
96
what is the thickest portion of the root?
cortex
97
where is the casparian strip?
endodermis
98
where does the water move when entering the xylem from the soil?
into the root hair cell in the epidermis then through the cortex, endodermis and pericycle before reaching the xylem
99
what is the apoplast pathway?
water moves in the cell walls, cellulose fibres in the cell wall are separated by spaces through which water moves
100
what is the symplast pathway?
water moves in cytoplasm and plasmodesmata, plasmodesmata are strands of cytoplasm through pits in the cell wall joining cells
101
what is the vacuolar pathway?
water moves from vacuole to vacuole
102
how does water move from the apoplast pathway into the xylem?
water can move through the apoplast pathway until it reaches the casparian strip which is made of suberin (hydrophobic). therefore the water has to move through the cell membrane into the cytoplasm and it moves along the symplast pathway to pass the casparian strip in the endodermis. then the water can either move back into the cell wall (apoplast pathway) or stay in the cytoplasm until it moves back into the cell wall to move into the xylem
103
how does water move from the root endodermis into the xylem?
1- increased hydrostatic pressure in root endodermal cells push water into the xylem. hydrostatic pressure is increased by active transport of ions into endodermal cells which reduces their water potential (more water moves in by osmosis), diversion of water to endodermal cells from the apoplast pathway
2- decreased water potential in the xylem so that it is lower than the endodermal cells. water potential is decreased by water being diverted to the endodermal cells by casparian strip, active transport of mineral ions from the endodermis and pericycle into the xylem
104
how are minerals taken into the cell?
active transport, move across the apoplast pathway in solution, diffuse in or be actively transported into xylem
105
what is the explanation for water moving up the xylem?
cohesion-tension theory
106
what is the cohesion-tension theory? (equation)
cohesion + adhesion + root pressure
107
what is cohesion?
attraction of water molecules for eachother, seen as hydrogen bonds, resulting from the dipole structure of the water molecule
108
what is adhesion?
attraction between water molecules and hydrophilic mol fuels in the cell walls of xylem
109
what is the cohesion-tension theory?
the theory of the mechanism by which water moves up the xylem, as a result of the cohesion and adhesion of water molecules and the tension in water column, all resulting from waters dipole structure
110
what is capillarity?
the movement of water up narrow tubes by capillary action
111
what is root pressure?
the upward force on water in roots, derived from osmotic movement of water into the root xylem
112
what is tension?
where the column of water is being pulled from above
113
how much water absorbed by the plant is lost?
99%
114
how is water lost?
continual evaporation
115
what is the process of continual evaporation known as?
transpiration
116
describe what happens to a plant if it loses too much water
the plant can’t regain its tutor so wilts and dies
117
how does temperature affect the rate of transpiration?
higher temperature means there is higher rate of transpiration due to lower atmospheric water potential
118
how does humidity affect the rate of transpiration?
higher humidity means there is a lower transpiration rate due to higher atmospheric water potential
119
how does wind affect the rate of transpiration?
higher wind speed means higher rate of transpiration due to water water vapour being blown faster
120
how does light intensity affect rate of transpiration?
the stomata are wider so higher light intensity means a higher rate of transpiration
121
what is the water availability and habitat conditions for mesophytes?
land plant, adequate water supply
122
how do mesophytes survive in unfavourable times of the year?
shed leaves before winter so don’t lose H2O by transpiration, aerial parts of non-woody plants die (underground organs survive), annual meosphytes= dormant seeds in winter = low metabolic rate
123
what is the water availability and habitat conditions for xerophytes?
land plant, water is scarce
124
describe the habitat of marram grass
no soil, rainwater drains away rapidly, high wind speeds, salt spray, lack of shade from sun
125
what is the water availability and habitat conditions for hydrophytes?
adapted to live in aquatic environments = lots of water
126
how are hydrophytes adapted to survive?
water is supportive so little or no ignited support tissues, little need for transport tissue, leaves have little or no cuticle as they don’t need to reduce H2O loss, stomata on upper side, large air spaces for buoyancy
127
what is translocation?
the transport of soluble organic molecules such as sucrose and amino acids in plants
128
how are products of photosynthesis transported?
translocated in the phloem from the site of photosynthesis (source) to all other parts of the plant (sinks) for growth and storage
129
what is phloem?
living tissue and consists of several types of cells including sieve tubes and companion cells
130
what is the structure of phloem?
sieve tube elements connected by sieve plates. companion cells on the rosie which are connected by plasmodesmata
131
explain the mass flow theory of translocation
1- sucrose moves from palisade cell to companion cell by facilitated diffusion
2- sucrose if moved from the companion cell to the phloem using ATP. sucrose is moved against the concentration gradient.
3- increased hydrostatic pressure in the phloem. water moves from xylem to phloem by osmosis
4- sucrose is actively transported out of the phloem
5- water from the phloem moves to the companion cell by osmosis. this reduces hydrostatic pressure in the phloem
6- some water is absorbed by the xylem
132
what experiments provide evidence for mass flow theory?
ringing, aphids, radioisotopes
133
what is the ringing experiment?
phloem is in the bark (outside) and xylem is in the actual stem. a ring of bark is removed. fluid accumulates above the ring leading it to swell. cells below the ring die as they don’t have sucrose for respiration.
134
what did the ringing experiment prove?
photosynthesis products are transported in the phloem
135
what is the aphids experiment?
aphids feed by putting mouthpiece into phloem. remove its body and leave the mouthpiece. sap leaks out of mouthpiece.
136
what does the aphids experiment prove?
the phloem moves under pressure. the sap is analysed and it shown to contain organic molecules
137
what is the radioisotope experiment?
plant is exposed to CO2 with C14 isotope only. the plant photosynthesises so its products contain only C14. A slice of stem is taken and put under X-Ray film which shows C14 is in the phloem
138
what did the radioisotope experiment prove?
photosynthesis products are transported in phloem
139
what type of cells is xylem made up of?
dead
140
what main cell types are in xylem?
vessels and tracheids
141
what are vessels (xylem)?
water-conducting structures in angiosperms comprising cells fused end to end making hollow tubes with thick lignified cell walls
142
what are tracheids (xylem)?
spindle shaped, water conducting cells in the xylem of ferns, conifers and angiosperms
143
what are xylem’s two functions?
transports water and dissolved minerals. providing mechanical strength and support
144
what is lignin?
hard, string and waterproof. Makes up xylem.
