3 - Exchange and Transport Sytems Flashcards
1
Q
What materials need to be exchanged
A
Oxygen , co2 ( respiratory gases)
Glucose, fatty acids, vitamins, minerals (nutrients)
Excretory products ( urea and co2)
Heat
2
Q
What 2 ways can substance exchange take place
A
Passively ( diffusion / osmosis )
Actively ( active transport)
3
Q
How do organisms evolve to meet the needs of SA:volume ration
A
Flattered shape so that no cell is ever to far away from the surface
Specialised exchange surface with larger areas to increases SA to volume ratio
4
Q
Simple diffusion of materials across the surface can only meet needs of……
A
Relatively inactive organisms
5
Q
Why are there Features of specialised exchange surface
A
To allow effective transfer of material across them by diffusion or activate transport
6
Q
What are the features of specialised exchange surfaces
A
Large SA to VOL ration to increase. The rate rate of exchange
Very thin so diffusion distance is show and therefore crosses the exchange surface rapidly
Particallly permeable to allow selected material to cross without obstruction
Movement of environment medium eg, air to maintain gradient
7
Q
How do you calculate rate of diffusion
A
Surface area x differnce in concentration
____________________________________________
Length of diffusion pathway
8
Q
Where are exchange surfaces located usually and why
A
Inside
As easily damaged
9
Q
Why do small organisms not need an exchange surface
A
Diffusion across their body surface is suffocating as the distances are short (less that 0.5mm)
Surface area is relatively large
10
Q
Area of circle formula
A
Pi r ^2
11
Q
Area of a square formula
A
B x h x l
12
Q
area of a sphere
A
4/3 pi r ^3
13
Q
Surface area of a sphere
A
4pi r ^2
14
Q
What do large organisms do to meet demands of O2 / minerals
A
A specialised exchange surface
15
Q
What 3 ways does gas exchange happen in insect s
A
1) along a diffusion gradient
2) muscle contraction
3) using water potentials
16
Q
How does gas exchange age in insects a long a diffusion gradient
A
conc of oxygen decreases along a tracheol
Causes diffusion gradient between atmosphereic O2 and cells
CO2 works in the opposite direction as cells respire
17
Q
Is diffusion quicker in air or water
A
Air
18
Q
How does gas exchange in insects
( contraction of muscle )
A
Mass transport
Contraction of muscles in an insect squeeze air in and out which speeds up exchange
19
Q
How does gas exchange in insects
( water potential)
A
The ends of the tradheoles are filled with water
During active periods, muscle cells around tracheoles carry out aerobic respiration
Produces lactate which us soluble thus lowers water potential of the muscle cells
Water therfore move into cells from the tracheoles by osmosis. The water in the end of the tracheoles decrease in volume thus increasing the amount of water which may fit in
20
Q
If you increase air into the tracheoles in an insect what does it lead to
A
Greater evaporation of water
21
Q
How can you reduce water loss from insects
A
Hairs whichh trap water
The spiricles close most of the time
22
Q
What are spiracles
A
Pores at the end of tracheoles om surface of insect
They can open and close by valves
23
Q
What can happen when spiracles are open
A
Water Vapor can evaporate so insects may have them closed
24
Q
Why do spiracles open periodically
A
To allow gas exchange
25
What are the similarities between stomata and spiricles
Open and close to reduce water loss
Positioned on the outside of the organism
26
Differences of spiracles and stomata
Spiracles have valves
Stomata have guard cells
27
Limitations of insects
Relies a lot on diffusion
Requiring a short diffusion pathway
The insect therefor has to be relative,y small
(Super hornets defy this)
28
what does photosynthesis use and release
Use co2
Release O2
29
What gases dowm respiration requires and which gas is released
Requires O2
Releases CO2
30
What reduces gas exchange with external air
In plants
At time gases for, one process can be used by the other
(respiration and photosynthesis)
31
Where does most of the O2 go from photosynthesis in plants and where does some go
Most diffuses out of lease but some used in respiration
32
Describe how gasses move out of leaves
Diffusion in the gaseous phase ( more rapid than in water )
No living cell is far from external air + therfore sources of O2 and CO2
short diffusion pathway, air spaces to provide very large Sa:V of loving tissues
33
Is there any specific transport system for gases in plants.
No there are just adaptations that cause raid diffusion
34
How does a leaf have a short diffusion pathway
As no cell is far away from the stomata
As airspace’s interconnect cells
35
Adaptations in plants for rapid diffusion
Shot diffuion pathway
Large SA od mesophyll cell for rapid diffusion
36
Where are the stomata located
Underside of leaves
37
What are stomata surrounded by
Guard cells
Which open and close the stomata pore
38
What do guard cells do
Control the rate of gaseous exchange and prevent loss of too much water by evaporation
39
What are the layers of a leaf blade
Waxy cuticle
Upper epidermis
Palisade layer }
Air spaces } spongy mesophyll
Lower epidermis }
40
What are phloem and xylem known as
Vascular bundle
41
What does the phloem transport
Sucrose + minerals
42
What does the xylem transport
Water + minerals
43
How many times denser us water than air and with what fraction of O2
1000 times denser with 1/30th the O2
44
How many time more viscous than air is water
100x
45
For fish Moving water in and out under water would use too much energy So what do they do
Only in one direction in counter current with bloof
Counter current flow maintains a favourable conc. gradient across the entire exchange surface
46
How do fish obtain the oxygen needed form the water
By the gills
As water flows of the bill surface respiratory gases are each edged between the blood and water
As % of dissolved oxygen in water is much less than air there are high rate of oxygen extraction form water
47
T or f
Fish have a closed circulatory system
Yes
48
What does it mean that fish have a closed circulatory system
The blood is entirely contained within the vessel
49
Do fish have a double circuit system
No single
50
What is a gill cover called
Operculum
51
What is inspiration
Mouth open
52
What is expiration in fish
Mouth closed
53
Describe fish gills
Many folded which are supported and kept apart for each other by the water
This gives them a high SA
54
How does gas exchange occur in fish
Diffusion vetween the water and blood across the gill memebrane and capillaries
The operculum permits exit of water and acts as a pump
55
Describe inspiration in fish
Oral valve opened
Mouth cavity expands taking in water through open mouth
Operculum is closed and moved outwards to assist water intake
56
Descirbe expiration in fish
Oral valve shirt s
Mouth cavity contracts forces water back across the gills
Operculum is open
57
What is rhe bony bar in fish called
Branchial arch
58
Describe how gas exchange rate in fish is optimised
A constant steam of oxygen rich water flows over the gill filaments in the opposite direction to the direction of blood flow through the gills. This is called counter current flow
Blood flowing through the fill capillaries Will encounter water of increase ot oxygen content , so the conc gradient for O2 across the grill is manintian across the entire distance of the hill lamella
59
What would happen if fish exchanged gas is parallel current flow
Wouldn’t achieve the same oxygen extraction r stem as conc across frill would quickly equalise
60
What vessel takes blood away form the bill
Efferent vessel
61
What vessel brings deoxygenated blood to the gill
Afferent vessel
62
What are gill plates
Folds in lamellase
Single cell layer
It’s the Exchange surface
63
What is the thickest part of the stomatal cell
Inner wall
64
What is the type of plant derived form a seed which contains two cotyledons
Dicotyledonous
65
What needs to be exchanged within the environment in an organism
Oxygen and nutrients
Waste products, co2 urea
Heat
66
How easy the exchange of substances depends on what
the organisms surface area to volume ratio
67
In single celled organisms how do substances exchange
And how fast
Can diffuse directly out of or into the cell across the cell surface membrane.
Diffusion rate is quick becuase of the small distance the substance have to travel
68
How does a single felled organism exchange surface and how fast
Diffuse directly across the cell surface membrane
Diffusion rate is quick becuase of the small distance
69
In multicellular animals why is diffusion across the outer membrane too slow
Some cells are deep within the body (there is a large distance between them and the outside environment)
Larger animals have a low surface area to volume ratio. It’s difficult to exchange enough substances to supply a large volume of animal through a relatively small outer surface
70
How do multicellular organism exchange substances
Exchange organs
Mass transport (eg, blood to carry glucose and O2, and I o ants water and solutes)
71
What 2 things does the rate of heat loss depend on
Shape and Size
72
Why does the rate of heat loss depend on surface area
Is an organism has a large volume it’s SA is relatively small, this makes it harder for it to lose heat from its body, if an organism is small is has a relatively large SA so heat is lost more easily. This means smaller organisms need a relatively high metabolic rate in order to generate enough heat to stay warm
73
How does shape effect rate of heat loss
Animals with a compact shape have a small surface area relative to their volume ratio - minimising heat loss form the surface
Animals weight less compact shape have a larger surface area relative to volume thus increases heat loss form the surface
Weather an animal is compact or not depends on the temp of the environment
74
Animals with hight surface area to volume ration tend to lose more water. How have some small desert mammals adapted
Kidney structure adaptations so they they produce less urine to compensate
75
To support their high metabolic rates what to small mammals livening in cold regions do
Need to eat large amounts of high energy food such as seeds or nuts
76
What adaptations do small mammals have when weather gets could
Thick layers of fur
or hibernate
77
How have larger organisms libing in hot regions adapted
Eg,
Elephants lathe flat ears to increase Sa to vol rayon
Hippos spend most day in water (behavioural adaptation)
78
What are Xerophytes
+ examples
Plants with are adapted to survive in very dry conditions
Marram grass / cacti
79
Feature or marram grass
Lives on Sandy ground where there is little water + may be very salty
Thick cuticle to reduce water loss
Stomata in pits
Pits surrounded by hairs, there trap layers of moisture outside stomata reducing diffusion gradient so less water is lost in transpiration
80
What are hinge cells
Allows leaf of marram grass to roll up when short of water so that stomata are not exposed to wind or dry air
81
What are some general features of xerophytes
Long shallow spread our roots
Swollen succulent stem
Leaves reduced to spikes
Round shape
Hairs on surface to reflect light
82
Why do xerophytes have long shallow spread out roots
Absorbs more water
83
Why do xerophytic plants have swollen succulent stem
To retain water
84
Why do xerophytic plants have leaves reduces to spikes
To reduce water loss ( as reducing SA to volume ration)
85
Why do xerophytic plants have leaves reduces to spikes
To reduce water loss ( as reducing SA to volume ration)
86
Why do xerophytic plants have round shape
Reduces SA to volume ratio
87
What do most exchange surfaces have in commmen
Large surface area
Thin
steep conc. gradient
88
Explain gass exchange in fish
Water, containing oxygen, enters the fish through its mouth and passes out through the gills.
2) Each gill is made of lots of thin plates called gill filaments,
which give a big surface area for exchange of gases.
3) The gill filaments are covered in lots of tiny structures called
lamella
(plural = lamellae)
lamellae, which increase the surface area even more.
4) The lamellae have lots of blood capillaries and a thin surface layer of cells to speed up diffusion.
5) blood flows through the lamellae in one direction and water flows in the opposite direction. This is called a counter current system. It maintains a large conc gradient between water and the blood. Thus conc of oxygen in the water is always high than in the blood so as much oxygen as possible diffuses form the water into the blood
89
Insects have microscopic air filled pipes called what?
Tracheae
90
Describe gas exchange in insects
Air moves into the tracheae through pores called spiracles
Oxygen travels down the conc gradient towards the cells
The tracheae branch off into smaller tracheoles which have thin permeable walls and go to individual cells. This means that oxygen diffuses directly into the respiring cells.
Carbon dioxide for the cells move down its own conc gradient gradient towards the spiracles to be released into the atmosphere
Insects use rhythmic abdominal movements to move air in and out of spiracles
91
What gases are needed in plants and why
CO2 FOR photosynthesis
o2 for respiration
92
What is the main gas exchange surface for dicotydonous plants
Mesophyll cells
93
What are th spores in the epidermis of the leaf called
Stomata
(Singular stoma )
94
How are you mesophyll cells adapted for their function
Larger SA
95
What controls the opening and closing of the stomata
Guard cells
96
How do insects minimise water loss
Close their spiracles using muscles
Also waterproof waxy cuticles all over their body and tiny hairs aorund their spiracles, both which reduce evaporation
97
How does water levels effect the opening or closing of stomata
Water enetrees the guar d cells making them turgid which opens the stomatal pore.
If a plant gets dehydrated the guard cells lose water and become flaccid which closes the pore
98
What are xerophytes
Plants adapted for life in warm dry windy habitats where water loss is a problem
99
What are some xerophytic adaptations
Stomata sunk in pits that trap moist air, reducing the concentration gradient of water between the leaf and the air. This reduces the amount of water diffusing out of the leaf and evaporating away.
• A layer of 'hairs' on the epidermis — again to trap moist air round the stomata.
• Curled leaves with the stomata inside, protecting them from wind (windy conditions increase the rate of diffusion and evaporation).
• Areduced number of stomata, so there are fewer places for water to escapes.
• Wary, waterproof cuticles on leaves and stems to reduce evaporation.
100
What must a gas exchange surface be like
Thin
Large SA
constantly ventilated
101
any factor that effects a gas exchange surface will effect what
Efficiency of gas exchange
102
Why do we need a breathing system
-all aerobic organisms require constant O2 to release ATP
- Build up of co2 - toxic to body (as acidic and can cause harm to enzyme action / organelles) - -volume O2 needed and vol ifCO2 removed is greater than that can be delt with by diffusion alone
- mammals also need to maintain body temp + have high metabolic c respiratory rates
103
Where are the lungs loacted in humans
In thorax protected by rib cage
104
Why can’t lungs exits outside the body
Air is not dense enough to support and protect the delicate structures
They would also dry out if outside the body
105
What is pulmonary ventilation
Total volume of air moved into the lung in one minute
106
Pulmonary ventilation calculation
Pulmonary ventilation = tidal volume X ventilation rate
107
What is tidal volume
Volume of air normally taken in at each breath when the body is at rest
108
What is tidal volume usually around
5dm-3
109
What is ventilation rate
The number of breaths taken in one muinet
110
What is ventilation rate normally
12-20 breaths in healthy adult
111
Units for ventilation rate
Dm3 min-1
112
Describe inspiration
The external intercostal muscles contract, while internal intercostal muscles relax
The ribs are pulled upwards and outwards, increasing the volume of the thorax
Diaphragm muscles contract, causing it to flattern, also increases the volume of the thorax
The increased volume of the thorax results in reduction of pressure in the lungs
Atmospheric pressure is now greater than pulmonary pressure, and so air s forced into the lungs
113
Describe expiration
The internal intercostal muscles contract, external intercostal muscles relax
Ribs move down and in, decreasing thorax volume
diaphragm muscles relax, returns to its upwardly domes position, decreasing volume of thorax
Decreased volume of thorax in cereals pressure in lungs
Pulmonary pressure is now greater that that of the atmosphere and so air is forced out of the lungs
114
Explain how air gets to the alveoli
as you breathe in air enters the trachea
The trachea splits into two bronchi - one bronchus leading to each lung
Each bronchioles then branched off into smaller tubes called bronchioles
The bronchioles end in small ‘air sacs’ called alveoli
115
What does ventilation consist of
Inspiration
Expiration
116
Is inspiration active or passive
Active
117
Is expirationactive or passive
Passive
118
Can expiration be forced
Yes
119
What happens during forced expiration
External intercostal muscles relax and inter costal muscles contract, pulling the rib cage further down and in
during this time , the movement of the two sets of intercostal muscles is said to be antagonistic
120
What is each alveolus made from
Single layer of thin , flat cells called alveolar epithelium
121
What are alveoli surrounded by
Network of capillaries
122
Descirbe gas exchange in the alveoli
O2 diffused out of the alveolu across the alveolar equilibrium m and into haemoglobin in the blood
Co2 diffuses into the alveoli from, the blood and is breathed out
123
Alveoli adaptation for gas exchange
Thin - short diffusion pathway
Large SA
Steel conc gradient - maintained by the flow of blood and ventilation
124
What is forced expiratory volume (FEV)
The maximum volume of air that can be breathed out in 1 second
125
What js forced vital capacity (FVC)
Maximum volume of air it is possible to breathe forcefully out of the lungs after a deep breath in
126
How can you figure out tidal volume, ventilation rate
Spirometer
127
How does TB effect the lungs
When someone becomes affected with tuberculosis bacteria, the immune system cells build a wall around the bacteria in the lungs. This form small, hard lumps known as tubercles
Infected tissue within the tubercles die and the gas is exchange surfaces damaged so tidlevolume is decreased
Reduce tide avoid means less can be inhaled at each breath so in order to take enough oxygen, they have to breathe faster so ventilation rate is increased .
Common symptoms therefore include persistent cough , coughing up blood and mucus, chest pains, shortness of breath and fatigue
128
How does fibrosis affect the lungs?
Fibrosis is the formation of scar tissue in the lungs. This can be result of infection exposure to a substance like asbestos or dust.
Scott tissue was thicker less elastic than normal lung tissue
Means lungs are less able to expand them so can’t hold as much air as normal so tidle volume is reduced There is a reduction in rate of gas exchange and diffusion slow across a thicker scarred membrane.
Symptoms include shortness of breath, dry cough, chest, pain, fatigue, and weakness
129
How does asthma affect the lungs?
Asthma is respiratory condition where airways become inflamed and irritated
During an asthma attack, the smooth muscle lining of the bronchioles contracts and a large amount of mucus is produced. This causes construction of the airways, making it difficult to breathe airflow in and out of the lungs is reduced so less oxygen enters the alveoli and moves into the blood reduced airflow means the forced expiratory volume is reduced Symptoms include wheezing, tight chest and shortness of breath
130
What is the effect of emphysema on the lungs
Emphysema is a lung disease caused by smoking and long-term exposure to air pollution. This causes inflammation, which tracks phagosites the area the phaosites producd anenzyme that breaks down the elastin, which is a protein found in the wars of the alveoli elastin is elastic. It helps alveoli to return to the normal shape after inhaling an exhaling Loss of elastin means I can’t recoil to as well. It was destruction of the alveoli wall which reduces the surface area of the alveoli so the rate of gas is exchanged decreases. The symptoms often include shortness of breathe and wheezing
131
What is the result of a reduction in gas exchange rate?
Less oxygen is able to diffuse into the bloodstream, the body cells receives less oxygen, and the rate of aerobic respiration is reduced. This means less energy is released, so the suffers often feel tired and weak.
132
Does correlation mean one thing causes another?
Not always
133
What should be the condition of your dissecting tools?
Clean, sharp and free from rust as blunt tools don’t cut as well and can be dangerous
134
In a lung dissection, how could you inflate the lungs?
Attach a piece of rubber tubing to the trachea and pump air into the lungs, using a foot or bicycle pump. Lungs will deflate by themselves because the last in the walls of the elastin in the walls of the alveoli
135
What is the trachea supported by?
C shaped rings of cartilage
136
How should you cut open the trachea in a lung dissection
Cartilage is tough you won’t open the trachea it’s best to cut it length way down the gap in the sea shaped rings use dissecting scissors or scalpels
137
How should you dissect a fish gill?
Place on a dissection tray,
gills are located on either side of a fish head, and they’re protected on each side by a bony flap called the operculum and supported by Gil arches
to remove the gillspush back to the operculum, use scissors to remove the gills . Cut each arch through the bone at the top and the bottom
138
How to carry out dissection on an insect
Fix insect dissecting board with pins to hold it in place,
Cut and remove a piece of exoskeleton from along the length of the insects abdomen. You can examine this trachea optical microscopes.
139
Ethical issues of dissecting animals
- morally wrong to kill animals just for dissections (however many dissections that are carried out in schools involve animals that have already been killed for meat)
- Concerns that animals used for dissection are not always raised in a humane way, (they may be subject to overcrowding, extremes or temps or lack of food or they may not be killed humanely)
- if animals are raised in school it’s important they are looked after properly and killed humanely to minimise suffering or distress
140
Features of the alveoli
- larger Sa to vol ratio
- movement of internal medium (eg, blood flow) maintain a diffusion gradient
- movement of environmental medium (air constantly moving in)
- very thin
-Partially permeable
141
Capillaries around the alveolu are ………, so what do red blood cells have to do
Thin
Squeeze through which increases the Sa of contact - they are also slowed so allows more time for diffusion
142
What % of oxygenated air is oxygen
21%
143
What % of oxygenated air is Co2
0.04%
144
What % of deoxygenated air is oxygen
16%
145
What % of deoxygenated air is co2
0.4%
146
What is digestion
The process by which larger molecules are hydrolysed by enzymes into small molecules which can be absorbed and assimulated
147
What does assimulated mean (digestion )
A part of the new composition
148
What does salivary amylase do
Hydrolysis alternate glycosidic bonds in starch to Disaccharide maltose in mouth
149
What maintains the PH in mouth and why
Minerals
For amylase optimum ( neutral)
150
why does no further breakdown happen in the stomach from amylase
Acidic conditions denature the amylase enzyme
151
Food in Small intestines - the remaining starch to maltose is broken down by what
pancreatic amylase hydrolase
152
What PH is the small intestines and how is it maintained
7-8
Bile
153
Maltose disaccharide is then hydrolysed into ……….. by ……….. in the ………..
Alpha glucose
Maltase
Ileum
154
How does maltase in the ileum work
Muscles in the intestine walls push food along ileum ( it’s epithelial lining produces the disaccharide maltose)
155
Is maltose secreted into the lumen of ileum
No
156
What is maltase a part of
The cell surface membrane of the epithelium cells of the ileum
157
What can maltase be described as
Maltase is membrane bound disaccharridase
158
Where is sucrase
Found in memebrane of the small intestines
159
Where is lactase found
Small intestine linning
160
What are proteins hydrolysed be
Peptidases
161
What do endopepridases hydrolyse
The peptide bond between amino acid in the centre of the molecule
162
What does exopeptidase hydrolyses
Terminal peptide bonds between amino acids at the end of each molecule , they release dipeptides and single amino acids
163
What does dipeptidase hydrolyse
The bond between 2 amino acids
164
Where are dipeptidase found
Part of the CSM of ilium epithelial cells
( they are membrane bound )
165
What hydrolysis lipids
Lipase
166
Where is lipase produced
Pancrease
167
What do lipase specifically hydrolyse to form what
Ester bonds found in triglycerides to form fatty acids and monoglycerides
168
What is a monoglyceride
Glycerol and 1 fatty acid
169
How does lipase work
fats and oils firstly split into tiny droplets called micelles by bile salts made in the liver (emulsification) this increases surface area so that the action of lipases is sped up
170
Why can’t large biological molecules cross cell membranes
And what does this mean
Too big
Can’t be absorbed form the gut into the blood
171
How can large molecules be broken down into smaller momlecukes
Hydrolysis reactions
172
What are hydrolysis reactions
Breaks bonds by adding water
173
Why are differnt enzymes needed to catalyse the breakdown of differnt food molecules
As enzymes only work with specific substrates
174
What is amylase
A digestive enzyme that catalyses the conversion of starch int the smaller sugar maltose
175
How does amylase digest starch
Hydrolysis of glycosidic bonds in starch
176
Where is amylase produced
Salivary glands
Pancrease (releases amylase Into small intestines)
177
What are membrane bound disaccharides and what do they do
Enzymes that are attached to the cell membrane of epithelial cells losing the ileum
Break down disaccharides into monosaccharides (involving hydrolysis of glycosidic bonds)
178
What enzyme breaks down maltose into what
Maltase
Glucose + glucose
179
What enzyme breaks down sucrose into what
Sucrase
Glucose + fructose
180
What enzyme breaks down lactose into what
Lactase
Glucose + galactose
181
How can monosaccharides be transported across the cell membrane of ileum epithelial cells via what
Transporter proteins
182
What does lipase catalyse the breakdown of into what
Lipids into monoglycerides and fatty acids
183
How does lipase work
Involves hydrolysis of ester bonds in lipids
184
Where are lipases made and where do they work
Pancrease
Small intestines
185
Where are bile salts produced and what do they do
Produced by liver and emulsify lipids
Causes the lipids to from small droplets
186
Why is bile salts important
Several small lipid droplets have a bigger surface area than a single large droplet
So the formation of small droplets greatly increases the surface area of lipid that’s available for lipases to work fro,
187
Once Lipid has been broken down, the moniglycerides and fatty acids stick with bile salts to from what
Tiny structures called micelles
188
What are protease?
Enzymes that catalyse the conversion of proteins into amino acids by hydrolysing the peptide bonds between amino acids
189
What is endopeptidase?
Ask to hydrolyse peptide bonds within a protein
190
Examples of endopeotidase
+ where they are synthesised + secreated
Trypsin
Chymotrtpsin
Pancrease - small intestines
Pepsin
Released into stomach by cells in stomach linning - only works in acidic conditions (hcl in stomach)
191
What is exopeptidases
Act to hydrolyse peptide bonds at the end of the protein molecule
They remove single amino acids from proteins
192
Examples of exopeptidase
Dipeptidases work specifically on depeptides
They act to separate rhe two amino acid that make up andipeptide by hydrolysing the peptide bond between them
Oftern loacted in CSM of epithelial cells in the small intestines
193
How is glucose absorbed in gut
By active transport with sodium ions via co transport proteins
194
How is galactose absorbed
Active transport with sodium ions via cotransporter proteins
195
How is fructose absorbed
Facilitated diffusion through a differnt transporter protein
196
What do micells help to move, monoglycerides and fatty acids towards? 
Epithelium,
197
Because micelles is constantly break up and reform they can release…………. Amd …………. Which allow them to be………
Monoglycerides
Fatty acids
Absorbed
198
Are whole micelles taken up across the epithelium
No
199
How are fatty acids and monoglycerides moved across epithelium cell membrane
They are lipid soluble so can diffusion directly
200
How are amino acids absorbed
Sodium ions are actively transported out of the epithelial cells into the ileum itself.
They then diffuse back into the cells through sodium-dependent transporter proteins in epithelial cell membranes, carrying the amino acid with them
201
What does RBC contain
Haemoglobin
202
What is haemoglobin
Large protein with a quaternary structure (4 polypeptide chains)
Each chain has a ham group which contains iron ion and gives it its red colour
203
What can haemoglobin bedescribed of having for oxygen
A high affinity for oxygen
204
How many O2 can each haemoglobin molecule carry
4
205
In the lungs, what joins to haemoglobin to form what
Oxygen
oxyhemoglobin
206
Is haemoglobin to oxyhemoglobin reversible
Yes
207
Is heamoglobin found in many differnt organisms
there are many chemically similar types of haemoglobin found in many differnt organisms , all of which carry out the same function
208
The partial pressure of oxygen (pO2) is a measure of what
Oxygen concentration
209
The greater the conc of dissolved oxygen in cells, the …….. the partial pressure
Higher
210
The partial pressure of carbon dioxide (pCO2) is a measure of what
The conc of CO2 in a cell
211
Haemoglobin affinity for oxygen varies depending on what
It’s partial pressure of oxygen
212
Oxygen loads onto haemoglobin to form oxyheamoglbin where there’s a ……
PO2
Oxyheamoglobun unloads its oxygen where there is a …….. pO2
High
Lower
213
Where does oxygen enter the blood capillaries
+ how
At the alveoli in the lungs
Alveoli have high pO2 so oxygen loads onto haemoglobin to from oxyhemoglobin
214
when a cell respires what happens to the pO2
It lowers
215
Where does red blood cells deliver oxyhemoglobin
To respiring tissue
216
What does a dissociation curve show
How saturated the haemoglobin is which oxygen at any partial pressure
217
What does 0% saturation on a dissociation curve mean
None of the haemoglobin molecules are carrying any molecules
218
What does 100% saturation on a dissociation curve mean
every haemoglobin molecule is carrying the maximum of 4 molecules of oxygen
219
Why is a dissociation curve s shaped
When haemoglobin combines with the first O2 molecule, its shape, alters in a way that makes it easier for other molecules to join two, but as the haemoglobin starts to become saturated it gets harder for more oxygen molecules to join as a result, the curve has a steep bit in the middle where it’s really easy for oxygen molecules to join the shallow bit each and is where it’s harder when the curves steep a small change inO2 cause a big change the amount of oxygen carried by the haemoglobin
220
haemoglobin gives up its oxygen more readily at .,…….. partial pressures of co2
Higher
221
When cells respire what do they produce and what does this raise
Co2
PCO2
222
what is rhe Bohr effect
When cells respire, they produce CO2, which raises the PCO2. This increases the rate of oxygen unloading( the rate of which Oxy haemoglobin disassociates to form oxygen and haemoglobin) so the dissociation curve shifts, right. the saturation of blood with oxygen is lower for the given PO2, meaning that more oxygen is being released
223
How organisms that live in environments with low concentration of oxygen adapted the haemoglobin to help survive in that particular environment
They have haemoglobin with a higher affinity oxygen than human haemoglobin, so their dissociation curves to the left of ours
224
How have organisms that are very active and a high, oxygen demand adapt the haemoglobin to help them to survive
Haemoglobin with a lower affinity for oxygen than human haemoglobin the curve is to the right of the human one
225
Haemoglobin + oxygen —> ?
What is special about this reaction
Oxyhaemoglobin
It’s reversible
226
Haemoglobin that bind readily with oxygen has what
A high affinity for oxygen
227
Describe the structure of haemoglobin
Globular protein
4 polypeptide chains
Each chain contains one haem (iron ) group
228
Hb + 4O2 —> ?
What is special about out this reaction
Hb(O2)4
It’s reversible
229
Secondary structure of haemoglobin
Coiled into alpha helix
230
Tertiary structure of haemoglobin
Folded into precise shape
231
Quaternary structure of haemoglobin
4 polypeptide chains are linked together to from an almost spherical molecule. Each polypeptide is associated with haemorrhaging group containing ferrous ion ( Fe 2+) . Each ion can bind with a single o2
232
How many oxygen can bind with one haemoglobin protien
4
233
Units of oxygen conc
Sa O2%
(Oxygen saturation - o2 bound to haemoglobin in blood)
234
For blood leaving the lungs what is the usual oxygen concentration
95 -99%
235
What is the PH like at gas exchange surfaces and why
higher due to low lever of acidic CO2 as it is constantly being removed
236
How does higher PH effect haemoglobin
Changes the shape into one that loads O2 readily amd increases the affinity of haemoglobin for O2, so it’s not released while being transported in blood to tissues
237
Why is there a lower PH at tissues
Co2 is being produced by respiring cells
Co2 lowers the PH
238
How does lower PH effect haemoglobin
Changed the shape of haemoglobin into one with a lower affinity for O2
239
Describe the effect of heamoglobin transporting oxygen when there is a higher rate of respiration
More Co2 produced
Lowwer PH
Greater haemoglobin shape change
More O2 unloaded
More O2 for respiration available
240
Adaptation of ileum to the function of absorbing products of digestion
Thin epithelium - once cell thick to increase diffusion rate
Microvilli increasss Sa for absorption
Lacteal
241
What is the lacteal
Tiny lymphatic vessel
242
What does the lacteal absorb
Fatty cards and glycerol
243
What do blood capillaries absorb
Glucose and amino acids
244
How does glucose and fructose and galactose and amino acids absorbed by ileum
Diffusion and co-transport
245
Absorption of triglycerides
• mono glycerices and fatty acids remain associated with bile salts after emulsification. Form miceues - tiny (4-7 m diamerer)
- as muscles contract and digestive procucus move through ileum the miceues come unto contact with epithelium cells linning the villi.
• here miceles break down releasing one monoglycendes and fatty acids
• as non-polas morecules oncy easy diffuse acoss the csm ento
Epithelial cells
• once inside epithelial cells, monoglycedes and fatty acids are transported to endoplasmic reticulum where they are recombined to form triglycerides
• This process starts in ER and continues un Golgi apparatus :
Triglycerides associated with cholesterol and upoproteins to form chylomicrons . special particles adapted for transport of lipids
Chlyomicrons move out of epithelium cells via excocytosis
They then reach lymphatic capillaries called lacteals (found in centre of each villus)
From the lacteal chylomicrons pass via lymphatic vessels, into the blood system. The triglycerides in the chylomicrons are hydrolysed by an enzyme in the endothelial cells or blood capillaries form where they diffuse into cells
246
Describe the route taken by the blood around the heart
Deoxygenated
Vena cava
Right atrium
Right ventricle
Pulmonary artery
Lungs
Oxygenated
Pulmonary vein
Left atrium
left ventricle
Aorta
247
Why do larger organisms need a transport system
They have a smaller surface area to volume ratio
So they can’t obtain all O2/glucose they need by diffusion
They need specialised circulator + gas exchange system
248
What 2 reasons increases need for a transport system
The lower SA to volume ration and the more active
249
Features of a transport system
Water liquid (blood) that readily dissolves substances and can be moved easily around
A closed system of branching vessels to distribute the transport medium to all parts of the organism
A mechanism for moving the transport medium
A mechanism to ensure flow is one direction + a awYbod controlling flow to meet demand
250
In mammals
They have a ……. Blood systems because
Closed
The blood is confined to vessels
251
What are the 3 types of vessels
Arteries
Veins
Capillaries
252
What vessel brings deoxygenated blood to the heart
Vena cava
253
What vessel brings deoxygenated blood to the lungs
Pulmonary artery
254
What vessel brings oxygenated bloof to the heart
Pulmonary vein
255
What vessel brings oxygenated blood away form the heart to the rest of the body
Aorta
256
What vessels are linked with the liver
Hepatic
257
Do (most of the time ) arteries have oxygenated or deoxygenated blood
Oxygenated
258
Do (most of the time ) veins have oxygenated or deoxygenated blood
- what is the exception
Deoxygenated
in the heart
259
What vessels are linked with the kidneys
Renal
260
What vessels are linked with the lower limbs
Iliac
261
Does haemoglobin change irs affinity for O2
Yes under differnt conditions
262
How does HB change its. Affinity fro O2
Chages shape in the presents of certain substances
Eg. CO2
263
How does co2 change HB affinity
Changes shape of HB
So HB combines more loosely to O2
This causes O2 to be released
264
Does a gas exchange surface or respiring tissue have …..
Have a high o2 conc
Gas exchange surface
265
Does a gas exchange surface or respiring tissue have …..
High co2 conc
Respiring tissues
266
Does a gas exchange surface or respiring tissue have …..
Low affinity of HB for O2
respiring tissues
267
Does a gas exchange surface or respiring tissue result in O2 being associated
Gas exchange
268
What is the degree of oxygenation of haemoglobin determined by
The partial pressure p(O2) in the surroundings
269
If P(o2) is lower
does HB carry low O2 or high O2
Low
270
Why does HB a have a reduced affinity for O2 in presents of Co2
And what is thus called
Co2 diffuses into blood to from carbonic acid
Which forms hydrogencarbonate ions that diffuse into plasma
Hydrogen ions remain in the RBC and are mopped up by HB to form haemoglobinic acid
The acid forces unloading of O2 and the **Bohr shift effect**
271
What way does the Bohr effect shift the curve
To the right
272
Why do animals with a larger Sa to vol ration shift the curve to the right
They loose heat quickly
So have a high metabolic rate to generate lots of heat
This shifts the O2 dissociation curve to the right
More O2 is neeed in respiring tissues, their Hb unloads it at a higher ppO2
273
Living in an environment with little oxygen requires a
haemoglobin that….
Readily combinds with o2
274
An organism with a high metabolic rate needs to
release
oxygen readily into the tissues.
275
Why do differnt haemoglobins have differnt oxygen affinit y
The shape of the molecule, haemoglobin
molecules have different sequences of amino
acids (different primary protein structure).
❑The shape of the haemoglobin molecules
determines their affinity for oxygen.
276
What are the 3 types of HB
Grabbers
Hoarders
Spenders
277
Give an example of a grabber Hb
And which way will the curve shift
animals that live at high altitude
To the right
278
Give an example of a hoarder Hb
And why
Lugworms are not very active, they spend most of
their time covered by seawater in their burrows.
▪ Oxygen diffuses into their blood from sea water
and haemoglobin transports it to tissues.
▪ When the tide goes out, the lugworm no longer
has oxygenated water to circulate and so it needs
to extract as much oxygen as possible from the
water left in the burrow which contains less and
less oxygen. It has haemoglobin with a high
affinity for oxygen – hoarders
279
Give an example of spenders HB
And why
Which way does the curve shift
birds / fish
Flying and swimming are energy demanding processes
They need more o2 for respiration and so their Hb dissociation curve shifts right so more O2 is releases in tissues at higher ppO2
280
What 3 ways is the flow of blood maintained
Pumping action of the heart
Contraction of skeletal muscles
Inspiratory movements
281
Describe the path of boood through the blood vessels form the heart
Arteries - Carry blood away form heart into…
Arterioles -
Capillaries
Venules
Veins
282
What are arterioles
Smaller arteries that control blood flow from artieries to capillaries
283
Learn layers of arteries, capillaries and veins form a diagram
284
What blood vessel has the widest lumen
Vein
285
Why do some blood vessels have ….
A tough outer layer
To Resists pressure changes form both sides
286
What are the tough outer layer of blood vessels made form
Connective tissues
287
Why do some blood vessels have ….
A muscle layer
To contract to control flow of blood
288
Why do some blood vessels have ….
Elastic layer
To maintain blood pressure by stretching and springing back
289
Why do some blood vessels have ….
Thin inner linning (endothelium)
Smooth to prevent friction
Thin to allow diffusion
290
Describe the layers of arteries
Thick muscle layer
Thick elastic layer
Overall large thickness
No valves
291
Why do arteries have….
A thick muscle layer
So can be constricted and dialated to control blood flow
292
Why do arteries have….
Thick elastic layer
Blood pressure needs to be kept High in arteries in order to reach extermeties of body
They are stretched at each beat of the heart
It recoils when it relaxes
293
Why do arteries have….
Overall large thickness
Stops the vessels bursting under pressure
294
Why do arteries have….
No valves
Blood is under constant high pressure and doesn’t flow backwards
295
What is the exception to arteries having no valves
The arteries leaving the heart
296
What are the layers of arterioles
Muscle layer thicker than arteri3s
Elastic layer thinner than arteries
297
Is the blood in the arterioles under higher or lower pressure than in the artery’s
Lower
298
Why do arterioles have….
Muscle layers thicker than arteries
Allows constriction of the lumen in order to control blood flow into capillaries
299
Why do arterioles have…
Elastic layer thinner than arteries
Blood pressure is lower
300
Is the blood in veins under high pressure
No
301
Describe the vein structure
Muscles relatively thin
Elastic layer relatively thin
Overall thickness small
Valves
302
Why do veins have…
Relatively thin muscles
Doesn’t control flow to the tissues
303
Why do veins have…
Relatively thin elastic layer
Low pressure will not cause them to burst
304
Why do veins have…
Overall small thickness
No need for thick walls as pressure is low
It also allows them to be easily flattened aiding flow of blood
305
Why do veins have…
Valves
Ensures blood doesn’t flow backwards
Body muscles contract
Veins compressed
Pressures blood within them
Forcing blood along vein
306
What is the function of capillaries
To exchange O2, CO2, glucose between blood and cells
307
Why is it an advantage for blood to move slowly in capillaries
Allows more time for exchange of materials
308
What is the structure of capillaries
Thin walls
Numerous + highly branched
Narrow
Narrow lumen
Pores in endothelium
309
Why do capillaries have…
Thin walls
So short diffusion pathway between blood and cells
310
Why is capillaries being numerous and highly branching an advantage
It creates a larger Sa
311
Why are capillaries narrow
Permeate tissue so that no cells far away form a capillary
And a narrow lumen - RBC squeeze flat against the side to bring them closer to the cell
312
Why do capillaries have…
Pores in endothelium
Allow WBCs to escape
313
What does blood transport
Respiratory gases
Products of digestion
Metabolic wastes
Hormones
314
What supplies blood to the heart
Coronary arteries
315
What is tissue fluid
The fluid that surrounds cells in tissues
316
What is tissue fluid made from,
Small molecules that leaves the blood plasma
Eg, o2, H2O and nutrients
317
Does tissue fluid contain RBC
No
318
Why Donets tissue fluid contain RBC
They are too large to be pushes through capillary walls
319
Cells take on ……. And …… from the tissue fluid and release……
Oxygen
Nutrients
Metabolic waster
320
Where in the capillaries do substances move out of the capillaries
And how
The capillary bed
By pressure filtration
321
What is pressure filtration
1) at the start of the capillary bed nearest the arteries, the hydrostatic pressure inside the capillaries is greater than tge hydrostatic pressure in the tissue fluid
2)This difference in hydrostatic pressure means an overall outward pressure forces fluid out of the capillaries and into the spaces around the cells, forming tissue fluid.
3) As fluid leaves, the hydrostatic pressure reduces in the capillaries
— so the hydrostatic pressure is much lower at the venule end of the capillary bed (the end that's nearest to the veins).
4) Due to the fluid loss, and an increasing concentration of plasma proteins (which don't leave the capillaries), the water potential at the venule end of the capillary bed is lower than the water potential in the tissue fluid.
5) this means that some water re-enters the capillaries form the tissue fluid at the venue end by osmosis
322
Where does and excess tissue fluid go
drain3d into the lymphatic system
Which transports this excess fluid from the tissues and puts it back into the circulatory system
323
Where is the heart loacted
Between lungs
Enclosed by pericardium
324
What is used to aid movement of heart.
pericardium fluid
325
What does rhe pericardium protect the heart from
Over expansion
326
What is the valve between the right atrium and right ventricle
The tricuspid valve
327
What is the valve between left atrium and left ventricle
Mitral valve
328
What is the valve between right ventricle and pulmonary artery
Pulmonary valve
329
What is the valave between aorta and left ventricle
Aorta valve
330
What are half of heart disease deaths from
Coronary heart disease
331
What does CHD effect
Coronary arteries
332
What do coronary arteries do
Supply the heart with glucose and oxygen
333
How can blood flow be impaired by CHD
By a build up of fatty deposits known as atheromas
334
If blood flow to heart muscle is interrupted it can lead to …..
Myocardial infarction
335
What is a myocardial infarction
Heart attack
336
What is an atheroma
Fatty deposits form within the wall of the artery
337
What are atheromas made of
Accumulations of wbc that have taken up low density lipoproteins
338
What can atheromas enlarge to form
Atheromatous plaques
339
What does atheromatous plaques cause
Bulge in the lumen
Takeing up room narrowing of arteries and blood flow is reduced
Leads to an increases risk of thrombosis or aneurism
340
How does an atheromas interrupt the smooth flow of blood
What does this cause
It creates a rough surface
Blood clot (thrombus)
341
What is a thrombus
Blood clot
342
What can a thrombus cause
May block the blood vessel
Rescuing supply of blood
Region deprived of blood oftern Dies as a result of
343
What is an embolism
A mobile clot
344
What causes a heart attack
Reduced supply of O2 to the muscles of the heart due to a blockage in the coronary arteries
If it occurs close to the junction in coronary artery and Aorta it will stop beating
345
What is an aneurysm
Artery walls bewecom weakens or damaged when elastic tissue is lost and hence swell
They may burst and cause internal bleeding
346
Heart disease Risk factors
Smoking
Blood cholesterol
Diet
347
How many times more likely are you to suffer from heart disease form smoking
2-6 times out of
348
What 2 factors increase risk of heart disease form smoking
Carbon monoxide
Nicotine
349
How can carbon monoxide lead to Heart disease
Combinds irreversible with heamoglobin to form carboxyheamoglobin which reduces oxygen carrying capacity og blood
The heart has to work harder to deliver the same amount of o2
High blood pressure increases risk of CHd and strokes
350
How does nicotine increase risk of heart disease
Stimulates adrenaline production which increases heart rate and raises blood pressure
Makes RBC more ‘sticky’ and leads to high risk thrombosis
351
What is cholesterol
An essential component of all cell membranes it is transported in plasma as spheres of lipoproteins
352
What are the 2 types of blood cholesterol
High density lipoproteins
Low density lipoproteins
353
What are high density lipoproteins
Removed chrolesterol from tissues and transports to liver for excretion
Helps protect against heart disease
354
What are low density lip proteins
Transports cholesterol form liver to tissues
Including artery walls which they infiltrated s
Leading to atheroma
355
How can diet increase risk of heart disease
High level of salts : raises blood pressure
High levels of saturated fats : increases low density lipoprotein
356
How can diet decrease risk of heart disease
Antioxidants (vitamin c)
Reduces risk of heart disease
Non-starch polysaccharides
357
Describe atria
have thin walls. They receive blood that is returning to the heart and force blood into the ventricles.
358
Describe ventricles
The ventricles have thicker walls than the atria. This is because they have to pump blood a further distance than the atria (out of the heart and to the rest of the body) and withstand higher pressures.
359
Pulmonary vein
Blood flows from…… to …….
Lungs
Left atrium
360
Aorta
Blood flows from
…… to …….
Left atrium
Body
361
Vena cava
Deoxygenated blood form body enters heart at….
Right atrium
362
Pulmonary artery
Blood flows from ,..,,.. to l…….
Right ventricle
Lungs
363
What do the truscupid and bicuspid valve do
) valves connect the atria to the ventricles. They stop blood flowing back into the atria when the ventricles contract a
364
Describe the route blood takes form left ventricles to left atrium
Left ventricle
Aorta
Body tissue
Vena cava
Right atrium
Right ventricle
Pulmonary artery
Lungs
Pulmonary vein
Left atrium
365
Describe double circulation system
Blood is pumped through heart twice when it makes a full circuit to ensure blood circulation isn’t to slow
366
What is the left side of the heart responsible for
pumping oxygenated blood out the body
367
What is the right side of the heart for
Pumps deoxygenated blood to lungs to become oxygenated
368
What is the Importance of the double circulation system in mammals
Maintained concentration gradient – this is due to oxygenated and deoxygenated blood not mixing.
Blood pressure to lungs is slower – to avoid damaging delicate tissues and increase time for gas exchange.
Blood pressure to body tissues is higher.
369
What are the plasma proteins
RBC
WBC
Platelets
370
What are the blood components
Plasma proteins
Ions
Digestion products
Hormones
371
What are the 3 body fluid types
Blood
Tissue fluid
Lymph
372
What is another word for interstitial fluid
Tissue fluid
373
What is ultra filtration
Filtration under pressure
374
What is tissue fluid
Water liquids bathes all cells of the body, which is formed from blood plasma
375
What does tissue fluid contain
Glusoce
Aa
Fatty acidic
Salts
Oxygen
Also recipes co2 and other waste materials from cells
376
What 2 things from tissue fluid
Hydrostatic pressure
osmosis
377
How does hydrostatic pressure form tissue fluid
Pressure of the blood form heart contractions forces fluid out of capillaries
Fluid moves out through gaps in the capillary walls
Some hydrostatic pressure form tissue fluid forces fluid back into capillaries - but net movement is only out
378
What moves when fluid is forced out of capillaries due to hydrostatic pressure
Dissolved gases and nutrients move with is
But larger plasma proteins and cells do not
379
How does osmosis contribute to formation of tissue fluid
A net movement of water from the capillaries due to hydrostatic forces
Fives them a more negative water potential
Water moves down the water potential gradient into the capillaries s
380
How is movement of fluid calculate
As a net figure of hydrostatic. Pressure and osmotic pressure
381
Hydrostatic pressure is much …..
At the arterial end of the capillaries then the venous end
So what does this mean for the net movement
Higher
Means the net movement is differnt at differnt ends of the capillary network
382
What is oedema
And what is it due to
Swelling
Due to a failure of lymphatic vessels
383
How does tissue fluid return to the circulator system
Blood at the venous end of the capillaries has a lower hydrostatic pressure than surrounding tissue fluid, hence some tissue fluid is forced back inside capillaries
The remainder drains into lymphatic vessels and is transported in the lymph until it drains back into the blood in subclavian veins
384
Symptoms of a myocardial infarction
Pain
Shortness of breath
Sweating
385
How long is the average cardiac cycle
0.8 seconds
386
Describe atrial systole
Cardiac muscles of atria contact
So volume of atria decrease
So blood pressure in atria increases
387
Describe ventricular systole
Cardiac muscles of ventricles now contact
Volume of ventricles start to decrease
Blood pressure in ventricles start to rise
When blood pressure increases above that it n atria the atrioventricular valves shut (audible lubb sound)
Blood pressure contains to rise as ventricular cardiac muscles continues to contact
Blood pressure now becomes greater in ventricles compared with arteries
Semilunar valves which have been shut until now open
Blood flows out of the heart into the aorta and pulmonary arteries
388
What are the 2 audible lubb dub sounds from in the cardiac cycle
Lubb - atrioventricular valves smal shut
Dub - semi lunar valves slam shut
389
What is atrial diastole
Occurs part way through ventricular systole
Atrial cardiac muscle relaxes
Pressure decreases and blood flows into atria from veins so volume increases
390
What is ventricular diastole
Cardia muscles of ventricles relax
Pressure in ventricles start to decrease and volume increases
When blood pressure drops below that in arteries, the semi lunar valves slam shut
On further relaxation, continued increase in volume and drip in pressure brings the blood pressure of the ventricles below that in the atria
Atrioventricular valaves now open and blood starts to flow into the ventricles form the relaxed but filling atria
391
Understand pressure changes in heart cycle - graph
.
392
Cardiac contraction is also called what
Systole
393
Cardiac relaxation is also called
Diastole
394
Define
Heart rate
Number of heartbeats per minute
395
Define
Stroke volume
Volume of blood ( cm ^3) pumped by heart in one beat
396
Define
Cardiac output
Stroke volume multiplied by the heart rate gives you amount of blood (cm3^3) pumped by heart in 1 min
397
Heart rate equation
#beats
________
Minute
398
Stroke volume calc
Blood (cm3)
—————
Beat
399
Cardiac output calc
Blood (cm3). #beats. Blood
——————- —————- = ———
Beat. Minuet. Minuet
400
What factors can change the cardiac output
Cardiovascular centre in brain
Hormones eg, adrenaline
Stretching of cardiac muscle
401
Where is blood pressure measured
In blood vessels barters
402
What is blood pressure determine by
Cardiac output and resistance of flow of blood in vessels
403
what is resistance to blood flow affected by
Diameter if boood vessels
Narrowwe vessels ( vasoconstriction)
Wider vessels ( vasodilation )
404
What factors effect bp
Cardiovascular centre
Smoking
Diet
Adrenaline
Increases blood viscosity
405
How does cardiovascular centre effect bp
Diameter of blood vessels controlled by
stimulation of sympathetic and parasympathetic
nerves
406
How does making effect blood pressure
Nicotine causes vasoconstriction
› Build up of fatty deposits in vessels
407
How does diet effect bp
High fat diet leads to build up of fatty deposits in
blood vessels
408
How does adrenaline effect bp
Causes selective Vadoconstriction and vasodilation
409
How does increase in blood viscosity effect bp
Excess water loss ( sweating / excessive ruination)
410
What is the control of heart beat cycle
1. SA node starts initial stimulation
2, a wave of excitation is started
3. The wave spreads across both atria
4. Atrial systole - blood I spushed into the ventricles
5. Excitation reaches the av node
6. The excitation reached the bottom of the bundle of his
7. Excitation passes along the purine fibres
8. The excitation moves up the sides of the ventricles
9.the ventricles contract in a wringing movement
10. Blood forces into arteries
11. The heart is relaxed
12. The atria refill with blood
13. The next cycle starts
411
What does xymes transport
Water + minerals
412
What does the phloem transport
Organic substances
Eg, sucrose
413
• Xylem & phloem tissues run close to each other to form……………(stem & leaves) or……….(roots)
Vascular bundle
Stele
414
In a leaf what is at the top of the vascular bundle
Xylem
415
In a leaf what is at the bottom of the vascular bundle
Phloem
416
Describe the fibres in the xylem tissue
Long cells with thickened cell walls for support
417
Describe the parenchyma in the xylem tissue
Cells with thin walls generally used as a storage
418
What are the elements of the xylem vessels
Dead cells (walls made of lignin, impermeable to water)
The end of the walls break down to form an uninterrupted
pathway for the water (xylem vessels)
Gaps in the walls called pits to allow movements between vessels
and/or living tissues nearby
419
What is transpiration
Plants take in water through their roots in the soil
And is lost through the leaves in the transpiration steam
420
Why do plants need to balence water loss and water uptake
Stomata open - more gas exchange but also more water loss
Stomata closed - less water loss but also less gas exchange
421
What does the rate of transpiration depend on
Temperature
Humidity
Air movement
Light
422
Water potential is always……… inside the moist
mesophyll than the atmosphere so transpiration occurs………..
Greater
All of the time
423
How does temp effect transpiration rate
As temp increases
Water molecules kinetic energy increase’s
So evaporation increases
424
How does humidity effect transpiration rate
Humidity decrease
Evaporation increases
425
How does air movement effect transpiration rate
Still air means saturation on the leaves increases
diffusion decrease
426
Why does light intensity effect rate of transpiration
As light intensity also affects the stomatal openinng
427
What are hydrophytes
Water plants
428
What are xerophytes
Plants living in very dry conditions
429
What are mesophytes
Plants living in normal conditions
430
How does water move upwards in plants
Concentration of water in the air is lower
than within the leaves
• Through the stomata, diffusion makes
water vapour move into the air.
• Water loss from the mesophyll cells lowers
their water potential, so the nearby xylem
vessel replace the lost water (diffusion)
• Water pressure in the xylem (in the leaf)
drops so water moves upwards from the
roots where there is higher pressure
431
What are the 3 water movement theories
Cohesion -tension
Root pressure
Capillarity
432
What is cohesion tension theory
Water in the xylem vessels is pulled (therefore
under tension) towards the leaves because of
the transpiration (transpiration pull).
Water molecules attract each other, because
they are dipoles. This provides cohesion
(stickiness) of the molecules, hence the
uninterrupted column of water.
433
What is the water movement theories for root pressure
In the roots, endodermis cells (around the
xylem vessels) actively transport mineral ions
into the xylem, reducing its water potential
water is drawn in hydrostatic pressure
increases water is pushed upwards
(mainly herbaceous plants)
434
What is the water movement theories - capillarity
Water molecules ‘climb up’ in narrow tubes (µm)
because they are attracted (adhesion) to polar
molecules of the tube.
The narrower the tube the higher the water
goes.
(mainly small plants)
435
Movement of water into / across roots
Water enters the plants through the root hairs (thin,
permeable, large surface area)...
...moving down a water potential gradient (by osmosis)
Why?
Because the vacuoles of root cells contain a strong
solution of dissolved substances, hence a lower water
potential than the soil
436
What are the possible water pathways through roots
Apoplast
between the root cells along the cell walls
Vacuolar
from vacuole to vacuole
Symplast
through the cell membranes , cytoplasm or
plasmodesmata (gaps in the cell walls)
437
As the water approaches the xylem, the
apoplast pathway is blocked by a layer of cells
(endodermis) surrounding the pericycle,……
So
Endodermis cells have thickened walls with
suberin (impermeable)
Suberin forms a band around these cells called
Casparian strip
The water is forced into the symplast pathway
and trough pits enters the Xylem
438
How are mineral ions taken up in p
Andy
Plants obtain the mineral from the soil (except
carnivorous plants and legumes)
• Nitrogen usually enters the plant as
nitrates/ammonium ions
• Ions move into the roots by diffusion (down the
concentration gradient) or active transport
• Ions move across the roots in solution in the water.
• At the endodermis these ions are actively
transported to by-pass the Casparian bands. Plants
can so be selective of the ion taken in
439
What does phloem tissue transport
And what is this called
substances made in
the leaves to all other parts of the plant. This
transport is called translocation
440
What does the phloem transport
Sucrose (soluble carbohydrates)
Amino acids
Hormones
Mineral
441
Translocation - transport of sucrose (sugar)
Mass Flow Hypothesis
1. Sucrose is manufactured in leaves from glucose made in photosynthesis
2. Sucrose is transported by facilitated diffusion into the companion cells
3. Hydrogen ions are actively transported from companion cells into phloem
along with sucrose.
4. This means the contents of the phloem now has a lower water potential than
the Xylem.
5. Water from the xylem moves by osmosis into the phloem creating a
hydrostatic pressure.
6. Respiring cells are using up sucrose which lowers their water potential.
7. Water then moves from the phloem into the xylem by osmosis.
8 The pressure is lowered in respiring cells
Sucrose moves from source to sink using the hydrostatic pressure gradient.
442
What is the mass flow hypothesis
Fluids can move freely in sieve tubes just
following the hydrostatic pressure gradient
Sucrose is actively loaded into the sieve tube
from the source cell (leaves or storage organ)
Water follows the sucrose (osmosis) so the
pressure in the sieve tube increases
A sink cell (respiring/storage tissue) unloads
the sucrose (+water because of the osmosis) so
the pressure in the sieve tube decreases
443
What are the 3 experiments to show phloem transports good substances
Using aphids
Ringing experiments
Radioactive tracers
444
experiments to show phloem
transport food substances
1. U s i n g A p h i d s
Aphid penetrates the stem into
the phloem using its mouthpart
c a l l e d stylet a n d s u c k s t h e
plant s a p
A feeding aphid can be
a n a e s t h e t i z e d a n d t h e stylet
c u t off
The phloem sap flows out
through the stylet a n d c a n b e
analysed. It is found to contain
s u g a r s a n d other organic
s u b s t a n c e s
445
experiments to show phloem
transport food substances - ringing experiments
In the ringing experiment, a ring of bark is scraped away that also
removes the phloem, exposing the xylem. Sugar then attempts to
move down the stem but is stopped by the ring. This is demonstrated
by a bulge of sugar forms above the ring, suggesting that sugar moves
down the stem in the phloem and water is transported by the xylem.
446
experiments to show phloem
transport food substances - radioactive tracers
These show the direction of
flow of sucrose, This
method uses radioactive
carbon dioxide (14C). This
radioactive carbon dioxide
is put in a bag over a leaf
and sealed. The carbon
dioxide gets converted into
glucose and an x-ray can
be taken that will show the
radioactive C in the phloem.
447
What is a photometer
A piece of apparatus used to estimate transpiration rates
Measure water uptake by a plant but assume the water uptake by plant is directly related to water loss by leaves
448
How can unused a potometer to estimate transpiration rate
1) cut a shoot underwater to prevent air from ene tearing the xylem, cut it ata slant to increases surface area available for water uptake
2)Assemble the potometer in water and insert the shoot underwater, so no air can enter.
Remove the apparatus from the water but keep the end of the capillary tube submerged in a beaker of water.
4) Check that the apparatus is watertight and airtight.
5) Dry the leaves, allow time for the shoot to acclimatise, and then shut the tap.
Remove the end of the capillary tube from the beaker of water until one air bubble has formed, then put the end of the tube back into the water.
6) remove the end of the capillary tube from the beaker of water until one air bubble has formed then put the tube back into the water
7) record starting position of air bubbles
8)start a stopwatch and record distance moved by bubble per unit time, the rate of air bubble movement is an estimate of transpiration rate
449
How can you dissect a plant
1)Use a scalpel (or razor blade) to cut a cross-section of the stem. Cut the sections as thinly as possible — thin sections are better for viewing under a microscope.
2) Use tweezers to gently place the cut sections in water until you come to use them. This stops them from drying out.
Transfer each section to a dish containing a stain, e.g. toluidine blue O (TBO), and leave for one minute. TBO stains the lignin in the walls of the xylém vessels blue-green.
This will let you see the position of the xylem vessels and examine their structure.
Rinse off the sections in water and mount each one onto a slide
450
What are sieve tube elements
Living cells that from the tube for transporting solutes, thus have no nucleus and few organelles
451
What is a companion cell
Carry out living functions for sieve cell
452
What are solutes sometimes called
Assimilates
453
What makes sure there is always a lower concentration at the sink of the source
Enzymes maintain a conc gradient at the source to the sink by chaining the solutes at the sink
454
Explain mass flow hypothesis
Active transport is used to actively load the solutes from companion cells into sieve tubes of the phloem at the source
This lowers the water potential inside the sieve tubes so water enters the tubes by osmosis from the Xylem and companion cells
This creates a high-pressure inside the tube at the source end of the phloem
At the sink, salutes are removed from thephloem to be used up this increases the water potential inside the sieve tube so water also leaves the tubes by osmosis
This lowers rhe pressure inside the sieve tubes
The result is a pressure gradient from the source end to the sink end
The gradient pushes solute along the sieve tube towards the sink
When they reach the sink for solute will be used up or stored
455
Give some against evidence for mass flow hypothesis
Sugar travels to many different sinks, not just to the one with She highest water potential, as the model would suggest.
The sieve plates would create a barrier to mass flow. A lot of pressure would be needed for the solutes to get through at a reasonable rate.
456
Explain how the translocation of solutes be demonstrated experimentally
Using C14
The Translocation of Solutes Can be Demonstrated Experimentally Translocation of solutes in plants can be modelled in an experiment using radioactive tracers.
1) This can be done by supplying part of a plant (often a leaf) with an organic substance that has a radioactive label. One example is carbon dioxide containing the radioactive isotope 14C. This radioactively-labelled COw can be supplied to a single leaf by being pumped into a container which completely surrounds the leal.
The radioactive carbon will then be incorporated into organic substances produced by the leaf (e.g. sugars produced by photosynthesis), which will be moved around the plant by translocation.
The movement of these substances can be tracked using a technique called
autoradiography. To reveal where the radioactive tracer has spread to in a plant, the plant is killed (e.g. by freezing it using liquid nitrogen) and then the whole plant (or sections of it) is placed on photographic film- the radioactive substance is present wherever the film turns black
The results demonstrate the translocation of substances from source to sink over time — for example, autoradiographs of plants
killed at different times show an overall movement of solutes (e.g. products of photosynthesis) from the leaves towards the roots.
457
What evidence support the mass flow hypothesis
• there is a pressure within sieve tubes, as shown by sap being released when they are cut.
• the concentration of sucrose is higher in leaves (source) than in roots (sink).
• downward flow in the phloem occurs in daylight, but ceases when leaves are shaded, or at night.
• increases in sucrose levels in the leaf are followed by similar increases in sucrose levels in the phloem a little later.
.metabolic poisons and/or lack of oxygen inhibit translocation of sucrose in the phioem.
- companion cells possess many mitrochondira and readily produce ATP
458
Evidence question the mass flow hypothesis
the function of the sieve plates is unclear, as they would seem to hinder mass flow it has been suggested that they may have a structural function, helping to prevent the tubes from bursting under pressure).
not all solutes move at the same speed - they should do so if movement is by mass flow.
sucrose is delivered at more or less the same rate to all regions, rather than going more quickly to the ones with the lowest sucrose concentration, which the mass flow theory would suggest.
