Michaelmas Flashcards
(204 cards)
1
Q
Define osmolarity
A
Number of osmoles of solute per litre of solution
2
Q
Define osmolality
A
Number of osmoles of solute per kg of solution
3
Q
Define osmole
A
Moles of osmotically active particles, effect osmosis
4
Q
Define osmotic pressure
A
Pressure required to stop movement of pure water into a solution
5
Q
Define water potential
A
Tendency for water to move from one are to another
6
Q
How does osmotic pressure and potential relate
A
High osmotic pressure means low water potential
7
Q
Define tonicity
A
Tendency to draw water in
8
Q
What is the pressure and potential of a hypotonic solution?
A
High water potential, low osmotic pressure
9
Q
Define physiology
A
branch of science that deals with function of living organisms and their systems and organs. First used by Jean Fernel
10
Q
What does autotrophic mean?
A
Can obtain carbon from inorganic compounds. Producing its own energy. E.g plants (via photosynthesis)
11
Q
Define homeostasis
A
maintenance of constant internal conditions and counter any deviation from the normal
12
Q
What variables are homeostatically regulated?
A
1) Temp
2)Osmotic pressure
3) Arterial BP
4) ECF volume
5) blood pH
6) Ion/ glucose concentrations
13
Q
What is a portal vein?
A
A vein that drains directly from one organ to another
14
Q
How is the pituitary gland controlled?
A
By hypothalamus. Hypothalamus releases hormones into anterior to control release of other hormones.
To posterior sends signals, as it is in direct contact
15
Q
What inhibits the sodium pump
A
Ouabain
16
Q
What is the Hodgkin cycle?
A
Cycle of the 3 stages of Na+ channel states, open, closed & inactive
17
Q
Define atrophy
A
The breakdown of muscle
18
Q
Define hypertrophy
A
The building of muscle
19
Q
What is myoglobin?
A
Protein that provides O2, found in striated muscles (myo)
20
Q
What is isotonic contraction?
A
Tension remains the same, so length of muscle changes
21
Q
What is isometric contraction?
A
When tension changes, however length of muscle doesn’t
22
Q
What are the 3 layers in blood vessels? From inside out
A
Tunica intima
Tunica Media
Tunica Adventitia
23
Q
What are the vessels that provide blood to vessel walls?
A
Vaso vasorum
24
Q
What are sphincters?
A
Circular muscles that open and close in passages to regulate movement of fluids. E.g. blood into dormant capillaries
25
What are local metabolites?
By-products of metabolism that cause vasodilation.
Aid the positive feedback loop
26
What are the names of the positive feedback loop in vessels associated with local metabolites?
Functional hyperaemia
Metabolic hyperaemia
Metabolic autoregulation
27
What does CKK do
Satiety signal released from stretching of the stomach. Signals fullness and stops eating.
28
What part of the brain controls feeding + Metabolism?
Hypothalamus, specifically the Arcuate nucleus
29
What kind of energy costs are involve in the acquisition of nutrients?
1) Foraging/ hunting
2) Enzyme production
3) Enzyme secretion
4) Absorption of nutrients
30
What is chyme?
Liquid slurry made in stomach released into the small intestine
31
What is the duodenum?
First part of the small intestine, mixes chyme, bile and pancreatic juices. It's connected to the stomach.
32
What and where are proteolytic enzymes released?
Enzymes that break down proteins,
many released in the stomach
33
What are the 4 compartments of a cow's stomach called?
Rumen, Reticulum, Omasum, Abomasum
34
Through which transporter are galactose and glucose moved through, into a cell?
SGLT1
35
Through which transporter is fructose moved through, into a cell?
GLUT5
36
Through which transporter are galactose, glucose and fructose moved through out of the cell?
GLUT2
37
How to calculate the respiratory quotient/ratio?
CO2 eliminated/ O2 consumed
38
Name 4 different mechanisms of carrying out gas exchange
1) Diffusion- unicellular
2) Alveoli- humans
3) Gills- fish
4) Tracheal system &spiracles- insects
39
What is Darcy's law?
rate of flow= change in pressure/ resistance
40
What are the 2 zones in the respiratory system?
Conducting and respiratory
41
What is the function of the conducting zone?
1) warm air
2) Filter out particulates
3) Phonation
4) Immune response
42
What are the 3 layers that make up the diffusion distance in humans?
1) alveolar epithelial
2) basement membrane
3) Capillary endothelium
43
Why is haemoglobin important?
Allows more O2 to be carried in blood
Acts as O2 sink
Maintaining diffusion gradient
44
What is the counter current flow?
When water and blood flow go in opposite directions, to maintain a diffusion gradient
45
Name 5 examples of ventilation
1) Cytoplasmic streaming
2) Insects- controlling spiracles
3) Gills- muscular contraction
4) Ram ventilation- swimming with mouth open
5) Breathing
46
What is the Functional residual capacity?
vol of air left after tidal exhalation ( ER+ RV)
47
What is inspiratory capacity?
Max volume breathed in from FRC, (TV+IR)
48
How do you calculate total ventilation rate?
Tidal Volume x Respiratory rate
49
What is dead space?
Part of the respiratory system where gas exchange doesn't occur
50
What is anatomic dead space?
The conducting airways, anatomically unable to carry out gas exchange
51
What is alveolar dead space?
Part of the alveoli which aren't perfused enough for gas exchange to occur
52
What is the A-a gradient?
gradient between theoretical and actual oxygen conc
53
What are nociceptors?
Receptors that detect signals from damaged tissues
54
Where are chemoreceptors located?
Peripheral and CNS, carotid body, aortic arch
55
What is hypercapnia?
High [CO2], caused by hypoventilation
56
What is an effective osmole?
can exert pressure and can't move through membrane
57
What is an ineffective osmole?
Doesn't exert pressure as it can move through the membrane
58
What is tonicity?
Tendency to bring water into itself
59
What is colloid osmotic pressure?
Pressure exerted by proteins and colloids in the solution
60
What is the difference in osmoregulation between marine invertebrates and vertebrates?
Invertebrates - bodily fluids similar to seawater
Vertebrates- bodily fluids very different to seawater
61
Name some examples of osmoregulatory organs
Skin
Kidney
Salt glands
Gills
62
How do marine mammals regulate water?
Use metabolic water
Their bodily fluid is hyposmotic to seawater so can't drink it
63
What is the structure of the urinary system?
Kidney
Ureter
Bladder
Urethra
64
What's the structure of the kidney like from outside to in?
Capsule, Cortex, Medulla (separated by renal columns)
65
What consists the renal tubules?
Nephron and collecting duct
66
What are the two types of nephrons and how are they different?
Cortical- more shallow
Juxtamedullary- loop of Henle found in inner medulla
67
Describe the blood supply into Bowman's Capsule.
Afferent arteriole in efferent arteriole out
68
What type of blood flow is present in kidneys?
Counter current
69
What is special about the blood supply to the cortex and the medulla in the kidney?
Independent of each other, so conc/dilute urine can be made
70
What are the 4 renal mechanisms?
Filtration
Tubular re-absorption
Tubular secretion
Urinary excretion
71
What are the particle sizes for ultrafiltration
Greater than 70,000 Da not filtered out
Less than 7,000 filtered out
72
What are the properties of the particles which regulate filtration?
Charge
Size
73
What are the 3 layers in the filtration barrier
Fenestrated capillary
Basement membrane
Podocyte
74
Why are proteins less likely to be filtered out?
Some are large
Exist as anions and the barrier has a fixed negative charge so repel proteins and don't allow them to be filtered out
75
How is the NET filtration pressure calculated?
hydrostatic + colloid pressure
76
Which pressure value is usually negligible in the kidney system?
Colloid pressure in Bowman's capsule, as not may colloids get through filtration
77
What does the glomerular filtration rate depend on?
Pressure
Permeability
Surface area
78
What is the avg filtration rate in humans?
125ml/min
79
What is the point of counter current multiplication?
Increase conc of solutes in medullary interstitial fluid
80
How much water and solute is absorbed in the proximal tubule?
65% of each
81
How much water and solute is absorbed in the loop of Henle?
10% water
25% of solute
causing uncoupling of the two
82
What is absorbed in the Distal convoluted tube and collecting duct?
More NaCl, little water
83
How is the cortical collecting duct permeability controlled?
ADH, controls water permeability
84
How is the medullary collecting duct permeability controlled?
ADH, controls urea permeability
85
How does urea move around, where does it diffuse in and out?
Out of inner medullary collecting duct
In thin descending limb
86
What is overall reabsorbed in the PCT and what compounds facilitate that movement?
Reabsorbed- Na+, Cl-, water
Helpers-
oxalic acid/oxalate (antiport)
amino acids (symport)
glucose (symport)
87
What are the transporters found in the thick ascending limb and where are they located?
Lumenal- NKCC2, K+ channel
Medullary Interstitium side-Na/K ATPase, K and Cl channels, K/Cl symport channel
88
What is the role of urea?
concentrating urine, to reduce water loss
By drawing water of thin descending limb
89
Why does urea not act as an effective osmole in the collecting duct?
The inner medullary collecting duct is highly permeable to it, so cannot exert an osmotic pressure
90
What does low [ADH] mean for urea?
More urea lost
91
How do cells of the medulla keep up with changes in volume?
Creating compatible solutes : sorbitol and betaine
92
What is the vasa recta?
Vessels that remove water and solute from medulla, without disrupting the osmotic gradient
93
How does the vasa recta remove water and solute without disrupting the gradient?
Counter current flow down and up the hairpin
Down, water out, solute in
Up water in, solute out
However equilibration is not complete, so removes some water and solute
94
What is the structure and half life of ADH?
Cyclic, with disulphide bridge, nonapeptide
Short half life (6-10min)
95
What does ADH do?
Osmoregulation
Vasoconstriction (known as vasopressin)
96
How is secretion of ADH control/ inhibited?
Reflexes in gut and liver
Osmoreceptors in hypothalamus
Arterial baroreceptors
Volume receptors in vessels
97
What are the 2 types of ADH receptors and where are they located?
V1= Vasoconstriction, in smooth vessels, low affinity to ADH
V2= osmoregulation, in kidney, high affinity to ADH
98
Where is ADH synthesised?
Magnocellular neurones in SON and PVN in hypothalamus
99
Where is ADH stored, ready for release?
Posterior pituitary gland, at the end of neurons in vesicles
100
How does ADH secretion occur?
Action potential travels down neuron
causes calcium-dependent exocytosis
101
How does ADH work on V2 receptors? And where are they located?
Binds to V2 (Gs-PCR)
activates adenylyl cyclase
cAMP made, activates PKA
PKA phosphorylates serine res 256 on AQP2
Vesicle fuse, AQP2 on membrane
Located in kidney
102
What is the water absorption rate limiting step?
Water absorption on luminal membrane
103
What is the mechanism of UREA permeability controlled by ADH?
Phosphorylation of urea transporter (UT)
Activates UT-A2 on thin descending limb
Promotes urea recycling
104
How do marine invertebrates osmoregulate?
They don't, isosmotic and same ionic composition as seawater
Examples: starfish, sea urchins
105
What is the hagfish a rare example of?
Marine vertebrate that is isosmotic with sea water, however ionic composition is different
106
How do marine elasmobranchs osmoregulate?
Salt secreting rectal gland
BF- isosmotic
Urine isosmotic to seawater
example: sharks
107
What transporters are present in salt glands of elasmobranchs?
NKCC1
Na/K ATPase
Cl- and K+ channels
108
What is the role of urea and TMAO in elasmobranchs?
Organic electrolytes that make up the difference required (gradient and charge?)
TMAO stops urea from denaturing proteins
109
How do marine teleost fish osmoregulate?
Gill
BF- hyposmotic
water lost across gills, replaces by drinking sea water
also have chloride cells secreting Cl-
110
Which type of marine animals drink seawater?
Marine teleost fish
marine birds
marine reptiles (turtles)
111
How do marine birds and reptiles osmoregulate?
Nasal salt gland
BF- hyposmotic
Drink seawater
hypertonic salt gland secretion
112
How do marine mammals osmoregulate?
Kindey
BF- hyposmotic
Survive off water from oxidative metabolism
113
How do freshwater teleost fish osmoregulate?
Gills also
BF- hyperosmotic
Don't drink water, water gain across gills
Urine hyposmotic
Have pavement and chloride cells
114
What is the role of pavement cells?
Active uptake from Na+ from freshwater
115
How does uptake of Na+ occur in pavement cells?
Na/ K ATPase creates conc gradient, drawing in Na+ from freshwater
Relative positive charge created by H+ ATPase to help movement
116
What happens when a migratory fish travels from freshwater to seawater?
Down regulation of H+ ATPase
Increase in no and activity of chloride cells
Increase in cortisol and growth hormone
117
What happens when a migratory fish travels from seawater to freshwater?
Up regulation of H+ ATPase
Decrease in no and activity of chloride cells
Increase in prolactin
118
How do amphibia osmoregulate?
Skin
BF- hyperosmotic
Gain water across skin
Lose salts across skin
119
How do birds osmoregulate?
Kidney, Cloaca
Kidney only able to produce slightly hyperosmotic to blood
120
How are mammalian and bird kidneys different to reptiles etc?
Contain a loop of Henle
121
How is the bird kidney different to a humans?
Not all nephrons in birds contain a loop of Henle
Overall a mix of mammalian -like and reptillian- like
122
How do insects osmoregulate?
Gut
Malpighian tubes
123
What are the transporters in malpighian tubes?
Na/K ATPase to remove K+ from haemocoel
H+ ATPase pumping H+ into lumen
NKCC2- removing Na, K 2Cl- from haemocoel
124
What are rectal pad cells?
Cells that reabsorb water by recycling ions in the rectal lumen
125
How do rectal pad cells help create dry excretion?
Increase in ion conc
Cause water to move through septate junction
Move down, ions recycled
126
How do mealworms create a concentrated excretion?
Counter current flow of fluid in malpighian tubule and rectal tubule, allowing further reabsorption
127
How is nitrogenous waste produced?
Amino acid catabolism
128
What are ammnotelic organism?
Organisms that secrete nitrogenous waste as ammonia (NH3), via gills as this requires lots of water
129
How is nitrogenous waster secreted in mammals and birds?
As urea, which also requires some water
130
What is the route for blood moving into the kidneys?
Renal artery->
Interlobar arteries->
Arcuate arteries->
Cortical radial arteries->
Afferent arterioles
131
What is the route for blood moving out of the kidneys?
Peritubular capillaries->
Cortical radial veins->
Arcuate veins->
Renal veins
132
How is the Nernst equation different to the Goldman- Hodgkin- Katz (GHK) equation?
Both calculate electrochemical potentials
GHK involves multiple ions
Nernst- to find equilibrium potential
GHK- find membrane potential
133
What is the absolute refractory period?
No matter how large the stimulus is, an action potential cannot be created
134
What is the relative refractory period?
Only a very large stimulus will cause the creation of an action potential
135
What kind of transmission is present for electrical synapses?
Gap junctions- Cells remain connected
Present in cardiac muscles
136
What kind of transmission is present for chemical synapses?
Vesicular transport- 'normal' synapse
137
What is the difference between ionotropic and metabotropic transmission?
Ionotropic- direct activation of channels by ions
Metabotropic- activation of channels, by secondary messengers e.g. neurotransmitters
138
What is temporal summation?
When there is a repeated stimulus over tiem
139
What is spatial summation?
When there are many stimulations at once, from different neurones
140
What route does the afferent and efferent neurone take? And what are their roles?
Afferent- to CNS - sensory
Efferent- from CNS - effect
141
What is the structure of the preganglionic neurone?
Myelinated
From CNS to ganglion
142
What is the structure of the post ganglionic neurone?
Unmyelinated
From ganglion to effector (muscle/ neurone)
143
What type of GPCRs are the 5 adrenergic receptors?
Alpha 1 = Gq
Apha 2 = Gi
Beta 1- 3 = Gs
144
Where are the 5 adrenergic receptors located?
Alpha 1- blood vessels
Alpha 2- presynaptic nerve terminals
Beta 1- Heart
Beta 2 - Lungs, smooth muscle
Beta 3- Adipose tissue
145
Which adrenergic receptors are stimulated by adrenaline and which by noradrenaline?
Adrenaline - 2 (alpha and beta)
Noradrenaline - 1 (alpha and beta)
146
What are the 6 functions of the respiratory system?
Gas exchange
Immune defense
Phonation
Acid base balance
Metabolism
Thermoregulation
147
What is nebulin?
Large protein that spans the length of the actin filament
Role is to set fibre length
148
What is titin?
Large protein
Functions as a spring
Gives muscles elastic properties
149
What makes up a motor unit?
Neurone
Muscle Cell
150
How can increased force be achieved in muscles?
Recruitment of more motor units
Asynchronous activation- some switched on and off
151
What are 2 examples of specialiased muscles?
1) Superfast twitch- generate high frequencies, high density SR, superfast myosin and SERCA pump
2) Insect Asynchronous muscle- Stretch of muscles lead to full force from muscle and creation of AP, stretching causes tropomyosin to move and expose receptors
152
What is atrophy?
Breakdown of muscle
153
What is hypertrophy?
Building of muscle
154
What are the differences between red and white muscle?
Red- more blood to it, fatigue resistant, aerobic respiration, lots of mitochondria
White- prone to fatigue, anaerobic respiration, more glycolytic enzymes
155
What is the difference between fast twitch and slow twitch muscle fibres?
Slow= Type I, postural muscles, lots of mitochondria, low Force/Area
Fast= Type II, flight muscles, high Force/area, Low fatigue resistance
156
What is the equation for work?
Force x Distance
157
What are the 3 sections in an ECG?
P wave- Atrial depolorisation
QRS wave- ventricular depolarisation
T wave- ventricular repolarisation
158
What is a phonocardiogram?
Records heart sounds are murmurs
'lub' AV valves close
'dub' SL valves close
159
What is the pathways of conduction in the heart, starting from the SAN?
SAN
AVN
Bundle of His
Purkinje fibres
160
What are muscarinic receptors?
GPCRs
Respond to acetylcholine
Located in the heart (SAN), vessels
M2 in heart- parasympathetic, decreases HR
161
What is Hypotension?
Low blood pressure
162
What is Hypertension?
High blood pressure
163
How is a sphygmomenometer used to measure blood pressure?
Listening for sounds of turbulent blood flow
Increase until quiet
Decrease until sound appears (Systolic)
Decrease until sound disappears (Diastolic)
164
What does systolic and diastolic mean?
Systolic- pressure when heart beats
Diastolic- Pressure when heart relaxes
165
Describe the cardiovascular response to exercise
1) Increase in cardiac output, HR and stroke volume
2) Increase in local perfusion (SA incr), recruit dormant capillaries
3) Local metabolites- Vasodilation, more O2, more respiration
166
What are the receptors for sweet, umami and bitter tastes?
T1R= nice
Umami - T1R1, T1R3
Sweet - T1R2, T1R3
T2R= bitter
167
What is the route of digestion in humans?
Mouth
Oesophagus
Stomach
Small intestine
Large intestine
Anus
168
What part of the hypothalamus signals hunger and what part signals fullness?
Lateral- HUNGER
Ventro-medial- FULL
169
What is bile?
Breakdown fat and neutralises acid
Produced in the liver, stored in gall bladder
170
What is the duodenum, jejunum and ileum?
Duodenum- first part of small intestine
Jejunum- middle part of intestine
Ileum- Last part of the small intestine
171
What does the hepatic system do?
The liver
Detoxifies blood
Stores glycogen
Secretes bile
172
How is mucin stored?
Stored in vesicles
Charge neutralised by Ca2+
When released, mucin forms bonds with water
Becomes mucus
173
What are the functions of saliva?
Lubrication
Initiate starch digestion
Neutralise acid
Immune response
Evaporation (heat loss)
174
What are the processes of mucus secretion?
1) Primary secretion- serous cells
- Isotonic with plasma
- permeable to water
2) Secondary modification- duct cells
- impermeable to water
- Retain Na+, swap for K+ using H+
175
What is the final concentration in the mucus dependent on?
Flow rate- how much time the duct cells have to modify the secretion
176
How are some animals able to digest chitin?
Have enzyme Chitinase
177
What are ways to digest cellulose?
Symbiotic relationship with organism that has cellulase
Fermentation of cellulose in the either foregut or hindgut
178
What are some examples of hindgut and foregut fermenters?
Foregut- monkeys, cows, sloths
Hindgut- horses, rabbits
179
What is the limitation of being a hindgut fermenter?
After fermentation in hindgut the food moves out
For foregut fermenters, the food is then passed through the digestive system
180
What are the 4 compartments of a cow's stomach? What are their roles?
Rumen- ferment
Reticulum- ferment
Omasum- pass food on
Obamasum- normal stomach, digest, secrete, absorb
181
What is the Renal Tubule structure?
1) Bowman's capsule
2) Proximal convoluted tubule
3) Descending thin limb
4) Loop of Henle
5) Ascending thin limb
6) Ascending thick limb
7) Distal convoluted tubule
8) Cortical collecting duct
9) Outer medullary collecting duct
10) Inner medullary collecting duct
182
Outline 3 difference and 3 similarities between the mammalian and insect respiratory system
Sim
- have adapted a large surface area
- can be bidirectional
- short diffusion distance
- take in O2 give out CO2
Diff
- insect can be unidirectional, contain many entrances and exits
- insects straight into cells, mammals into RBC
- mammals have nasal cavity to store water
183
How, when and from where is ADH released? What are the actions of ADH on the mammalian kidney?
Produced in hypothalamus
Released from posterior pituitary
Controlled by baroreceptors (BP and water content)
Increase the permeability to urea in the inner medullary collecting duct
More AQP2 to absorb more water
184
List 3 effects of sympathetic nerve stimulation on the cardiovascular system and a further 3 effects on thermoregulation
Cardio
- Increase HR, BP and cardiac output (beta-1)
- Vasoconstriction, Sympathetic tone created
- Stronger contractions, greater pressure
Thermo
- Increase sweating (sweat glands)
- Increase shivering
- Controlling vasoconstriction (sympathetic tone)
- cause piloerection
185
List TWO points of similarity and TWO points of difference relating to how a skeletal muscle fibre and an auditory hair cell in the mammalian inner ear become electrically excited, under normal circumstances (focus on those specific cells only, not any other cells that might be involved).
Sim
- both involve neurotransmitters
- both are depolarized when activated
- Depolarisation carried out by ion channels
Diff
- mechanical stimulation in auditory hair cells
- hair cells is for sensory, muscle fibre more of an effector
- hair cells lead to a more graded response
186
Given action potentials are all-or-none events, how is a graded force produced by a single motor unit?
Spatial and temporal summation
[Describe]
More AP leads to more Ca release
More Ca binds to troponin to allow formation of actin-myosin cross bridges
Allowing for stronger contractions of muscle
187
Explain how the autonomic nervous system contributes to the cardiovascular baroreflex response to a decrease in arterial blood pressure
Decrease in blood pressure detected by baroreceptors in arteries (carotid)
Response is vasoconstriction
Adrenergic receptors are located in smooth muscle (alpha 1)
Activated by noradrenaline from adrenal gland
Also heart can beat faster to increase pressure (beta 1)
188
Summarise the key features which distinguish C3, C4 and CAM pathways.
C3 uses Rubisco, C4 and CAM uses PEPC
C4 and CAM create a 4 carbon compound
CAM is temporally separated, however C4 is spatially separated
Structure of the leaf is different C4 has Kranz anatomy
189
Briefly describe three similarities and one difference between shoot and root apical meristems.
Sim
- Both contain rapidly dividing cells
- Cells can be undifferentiated stem cells
- Have a developmental role
Diff
- RAM has a root cap for protection
- Structure of zones is different
190
Outline the events that occur in plant non-host resistance.
Reinforcement of physical barriers, by lignin
SAR (systemic acquired resistance) SA released to warn other tissue
PAMP (pathogen associated molecular patterns)- released by pathogen
Can then trigger immunity (antimicrobial compounds)
191
Briefly compare the challenges posed by gravity to fluid transport in plants and animals and how these are overcome
Challenge is to move fluid against gravity
Also mammals to avoid blood pooling
Animals- higher blood pressure, from heart beating more, vessels constriction, Veins have valves to stop backflow
Plants- rely on transpiration and water cohesion,
narrow xylem vessels to maintain high pressure
192
Briefly explain how plants might signal and respond to salt stress
Signalled by Ca2+, ROS signalling
- storage in a vacuole
- storage in vacuole of dying leaves (sea arrowgrass)
- compatible solutes (mannitol and proline)
- inclusion, use the ion gradient for uptake of water combined with compatible solutes to prevent toxicity
193
Summarise the ways plants can increase their acquisition of nitrogen.
Form symbiotic relationships with mycorrhizal fungi
Increase surface area of roots
More NRT1.1 receptors to move in nitrate
Remobilize nitrogen from old sources to new leaves
194
Write brief notes on the similarities and differences between the interactions of plants with fungal biotrophs and with mycorrhizal fung
Biotrophs- not symbiotic could cause harm to plant, uses up nutrients but doesn't aid acquisition. may trigger defence response
Mycorrhizal- symbiotic relationship, mutually beneficial
Sim
- both form relationships with the roots, both exchange nutrients
195
Compare and contrast the properties of wood in conifers and angiosperms
conifers- softwood, tracheids, stronger more rigid, greater amount of lignin, greater porosity
Angiosperms- more flexible, hard wood, less lignin contain vessels elements
196
Compare and contrast the properties of wood and bone
Wood- cellulose, hemicellulose, lignin
Bone- collagen and hydroxyapatite
Properties- Wood is less flexible, strong in tension
Density- bone is denser
Same function- strength, stability
197
What are the advantages of using tendons instead of muscle?
Tendon, takes up less space
More efficient, stores more elastic energy
Useful for stability
Lower metabolic cost
198
Briefly explain how vertebrates transduce olfactory signals
Olfactory long receptors in nasal cavity
Triggers Golf (cAMP cascade)
opens cyclic nucleotide channels
Ca2+ and Na+ allowed in
Depolarisation
Straight to olfactory cortex
199
List the factors influencing flow through a cylindrical vessel. What would be the effect of halving vessel radius? Give one example from animals and one from plants of when flow- rate through such a vessel would be substantially reduced below normal.
halving would decrease the rate by 16fold
By Poiseuille's Law
Viscosity, radius, length of vessel
Plant- embolism
Animal- athersclerosis
200
How would you calculate the resilience of a biological material? Outline the experimental procedure you would use and how you would calculate resilience from the data obtained
Measure tensile or compressional strength
Plot a stress- strain curve
stress= force/ cross sectional area
Strain= deformation/ original length
Area underneath represent resilience
Resilience= ability to absorb and store elastic energy
201
List the main functions of: the glomerulus, the proximal tubule, the loop of Henle, the collecting duct and the vasa recta
Glomerulus- filtration, moves out water and solutes from the blood stream retains the large proteins in the blood
Proximal tubule- reabsorption, 65% of water and solutes is reabsorbed
Loop of Henle- counter current system to control and concentrate the uring, with the descending limb being permeable to water and ascending limb actively pumping out ions
Collecting duct- controls the conc of urine, permeability to water is controlled by ADH
Vasa Recta- blood vessels that remove solutes and water from the interstitial fluid, without changing the osmotic concentration in the counter current system
202
What pieces of evidence are there for the presences of miniature end plate potentials (mEPP)?
mEPP- small potentials caused by accidental exocytosis of vesicles
1) Curare- drug that binds to NAChRs so blocks ACh, changes in potential suggests that ACh is responsible
2) Electrophysiological readings- readings of EPP, shows a small hump of depolarisation, not caused by nerve stimulation
3) Vesicle release blockers- block the exocytosis of neurotransmitter, leading to lack of mEPP and EPP, suggesting that ACh has a role
4) Ca Channel blockers- stops the movement of Ca, which means exocytosis can't occur, again mEPP not created suggesting that it is formed by spontaneous release of neurotransmitter
203
List 3 advantages and 3 disadvantages of a cardiovascular system
Adv
- higher metabolic rate
- bulk flow of nutrients
- organisms can become larger
- regulation of blood flow
Disadv
- Reliance on heart and vessels
- higher metabolic cost (O2 required)
- higher pressures required (dangerous)
- more stress on vessels
204
Compare and contrast salivary secretion and sweat secretion
Sim
- both use Na/K ATPase to secrete ions
- both innervated by autonomic and are cholinergic
Diff
- sweat= sympathetic, salivary= parasympathetic
- sweat doesn't undergo a lot of secondary modification
- location of glands secreting is different
- trigger for secretion is different
