TMA Flashcards
1
Q
What is adaption?
A
A trait that enhances fitness and is a result of natural selection.
2
Q
Explanations for non-adaptive traits?
A
> Phylogenetic constraint (baggage). > Design constraints (limiting factors). > Sexual selection. > Neutral features. > Co-variation. > Exaptation. > Random genetic drift.
3
Q
What is a key Innovation?
A
A novel trait providing an evolutionary advantage.
4
Q
What is Adaptive radiation?
A
Explosion of speciation in a lineage linked to a key innovation.
5
Q
Describe biological evolution?
A
Descent with modification
6
Q
What is exaptation?
A
A feature having a function for which it was not originally adapted.
7
Q
What is Developmental Platicity?
A
Alterations of phenotypes during growth, due to environment (can enhance evolution).
8
Q
What are some of the archosaurian (dinos, birds, reptiles) adaptations as a result of a wider activity range?
A
> Erect posture. > 4-chambered heart. > Parasagittal gait. > Hingelike joints. > Endothermy.
9
Q
What is drag?
A
A force generated by a solid moving through a liquid.
10
Q
What is Cursorial?
A
Specialised for running.
11
Q
What is Scansorial?
A
Specialised for climbing.
12
Q
What is Fossorial?
A
Specialised for digging?
13
Q
What is Arboreal?
A
Specialised for tree locomotion
14
Q
What are the 2 different posture types?
A
> Sprawled.
> Erect/upright.
15
Q
What are the 3 main factors of motion?
A
POSITION, VELOCITY and ACCELERATION
16
Q
What must ‘Ground Reaction Forces’ equal?
A
Body weight
17
Q
What is the largest component associated with support of weight?
A
Vertical ground force
18
Q
What is optimisation?
A
The Idea of improving for a different lifestyle.
19
Q
What are the main features of early tetrapod locomotion?
A
> Sprawling posture. > Lateral bending of trunk. > Relatively massive distal limbs. > Same muscles for ventilation and trunk stabilization. > Limited endurance. > Limited aerobic scope.
20
Q
What are some morphological adaptations for endurance and speed?
A
> Upright posture. > Stable trunk. > Reduction in distal mass. > Elongated legs. > Elastic tendons.
21
Q
What are ungulates specialized for?
A
ENDURANCE and SPEED
22
Q
What are some adaptation for economy and speed?
A
> Elongation of distal limb. > Lightening of distal limb. > Reduction in number of bones. > Tendons act as pulleys and springs. > Saggital plane motion (forward) > Los of phalangees > ungilate.
23
Q
What is an ungilate?
A
A hoofed mammal.
24
Q
What are some physiological adaptations for endurance?
A
> High aerobic scope.
Temperature regulation.
Mitochondrial density in muscles.
Red blood cell volume.
25
What is plantrigrade motion?
Walking on soles of feet (human)
26
What is digitigrade motion?
Walking on toes or digits (dog)
27
What is ungiligrade?
Walking on hooves (horse)
28
What sort of interaction does terrestrial locomotions involve?
CYCLIC
29
What's Newton's 2nd Law?
Force = mass x acceleration
30
What's Newton's 3rd Law?
Every action has an equal and opposite reaction.
31
What does Inversley proportional mean?
When one value increases the other value decreases.
32
What is bernoulli's principle?
Faster Flow = Lower Pressure
33
What is the Coanda effect?
A moving stream of fluid in contact with a curved surface will tend to follow the curvature of the surface rather than continue travelling in a straight line.
34
What important feature do all wings have?
Sharp trailing edges.
35
What is the kutta condition?
When the airflow above and below the wing is going in the same direction.
36
Is the pressure Lower or Higher above an airfoil?
Lower
37
In order to increase lift, do you need a higher or lower wing area?
Higher
38
How does drag effect bird flight?
> When gliding drag is a hinderance as it reduces speed.
| > When flapping the angle of incident airflow is changed - drag is balanced.
39
Do birds have gaites?
No, flight is a spectrum.
40
When wing aspect ratio is high how does this effect drag?
Drag is reduced.
41
What kind of wings have high aspect ratio?
Long narrow wings.
42
How do wings generate lift (conventional)?
> Air is accelerated over the upper surface.
> Then over a sharp trailing edge.
> creating a bound vortex.
43
What are the unconventional ways of generating lift?
Using a sharp leading edge (at the expense of fuel economy)
44
What is parasite power?
The power required to overcome the drag of the body.
45
What kind of wings have low induced drag?
Long wings
46
What kind of wings have low profile drag?
Low area wings
47
What is classified as extreme gliding?
Gliding with wings with a higher aspect ratio than 50.
48
What's the point of a high aspect ratio?
Minimise angle and drag and maximise lift.
49
What is thermal soaring?
Soaring using rising air heated from the sun.
50
What is soaring?
Rising in the air without the use of flapping or engine power - using energy in the air.
51
What is gliding?
Flying without flapping or engine power.
52
What is dynamic soaring?
Using different air masses and velocities (wind) to gain hight.
53
What is slope soaring?
Using air running off slopes to gain lift.
54
What does flapping flight require?
> Ability to withstand high forces.
| > Lots of power - because of how active it is.
55
What is inertial power?
Tendancy of an object to keep moving in a straight line at a constant velocity.
56
What's the problem with slow flapping flight?
Extremely inefficient > compromised inertial power.
57
Name 7 different types of flight?
```
> Soaring
> Gliding
> Quartering
> Loitering
> Migrating
> Underwater
> Display
```
58
What's the name of the type of flight used for surveying the ground?
Quartering
59
What kind of flight has the purpose to stay up as long as possible?
Loitering Flight.
60
What features are usefull for maneuvering?
> Short wings
> Long tail
> Slow flight
61
Why do birds fly in a V-formation?
> Aerodynamic benefit.
| > Vision benefit.
62
Why do birds fly in flocks?
> Vigilance.
> Predator dilution.
> Crowd wisdom.
63
Why is aerodynamic theory developed for aircraft sometimes not usefull for understanding birds form and function?
> Birds flap.
| > Birds need to be able to perform many functions.
64
How are frogs modified for jumping?
> Increased spinal flexibility.
> Modified pelvic bones: elongated ileum (hinge), Appearance of urastyle, fusion of sacral bones.
> Elongation of hind limbs (bigger lever).
> Modifed muscles.
> Long, stretchy tendons.
65
How are frogs modifeid for landing?
> Pre-activated fore-limbmuscles.
> Abdominal ribs (absorb impact).
> Fused radius + ulna.
> Supra-scapula cartilage.
66
How much larger are landing forces compares to takeoff?
3 x larger
67
How are frogs modified for walking?
> Modified ileum- rotating pelvis.
> Bi-lateral co-contraction of leg muscles.
> Longer fore-limbs.
68
How are frogs modifed for swimming?
> Reduced for-limbs.
> Webbed feet.
> Small body area.
> Central Jet theory.
69
How are frogs modified for aquatic jumping?
Modified foot morphology - high surface area.
70
How can frogs increase their jump distance?
> Increasing force - increases acceleration.
| > Increasing speed - increases duration.
71
What are the 3 primary requirements for terrestrial legged locomotion?
> Move the centre of mass (COM).
> Support body weight against gravity.
> Move limbs into position for stance.
72
What is the largest force that acts on an animal during locomotion?
Vertical ground force.
73
What's the equation for vertical ground force?
vertical force = -mass x gravity
74
How can vertical ground force be minimized?
More limbs on the ground.
75
What must horizontal forces average to maintain a steady speed?
zero
76
What happens to peak forces when speed increases?
They increase.
77
What are the ground reaction forces experienced by a horse during walk, trot and canter?
> Walk - 1/2 body weight.
> Trot - 1 times body weight.
> Canter - up to 2.5 body weight.
78
When are injuries most likely?
At high speeds.
79
What is strength proportional to?
Cross sectional-area
80
What is loading proportional to?
Body mass and volume.
81
What happens to animals as they get larger if they don't change shape?
They get weaker.
82
Which increases fastest out of area and mass when size is increased?
Mass increases faster.
83
Name a benefit of large body size?
Excellent fuel economy.
84
Name a benefit of upright limb posture?
Decreases required muscle forces.
85
What must average vertical force support?
Body weight
86
What features minimise energy cost?
> Minimal horizontal forces.
> Pendulum mechanism during walking.
> Spring mechanism during running.
87
Name 2 Features of lizard locomotion?
Lateral body undulations .
| Sprawling posture.
88
Name a feature of lizard ventilation?
Exhalation powered by hypaxial muscles.
89
How do Lizards integrate Loc + Vent?
Same muscles used for both - Lizards cant run and breath.
| Limited endurance and aerobic scope.
90
What are the features developed by mammals and birds in order to avoid constraints on locomotion and ventilation?
> Upright posture.
> Saggital bending.
> Lateral stability - allawing muscled to function for ventilation.
> Diaphragmatic - don't have to use body wall muscles.
> Bipedal locomotion - reduced use of body wall.
> Locomotor-ventilatory coupling - rhythm of breathing during running.
91
What is locomotor-ventilatory coupling?
Integrating the 2 functions to achieve both effectively.
92
What is the visceral piston model?
Using the cranial movement of the guts during locomotion to aid exhalation.
93
Name 3 different ways animals exhale?
> Buccal pump mech (frogs).
> Using hypaxial muscles (lizards).
> Costal (rib-cage) breathing (mammals).
94
Why did loc + vent coupling develope?
```
> Help do work of breathing.
> Avoid muscle conflict.
> Mixing of air - improve gas diffusion.
> Pneumatic stabilisation.
> Accident of neurol feedback.
```
95
Does loc + vent work together in turtles?
No - turtles have mechanically independant systems.
96
Does loc + vent work together in humans?
Partly - humans have to coordinate breaths and steps.
97
How do you measure locomotor driven ventilation (LDV)?
By averaging ventilatory flow relative to the step cycle.
98
What is the main source of energy loss and horizontal forces during locomotion?
Collisions.
99
How can energy loss during collisions be minimised?
> Effective ankle push off.
| > Effective foot rolling.
100
Name some advantages for plantrigrade posture?
> Effective ankle push off.
> Effective foot rolling.
> Effective elastic energy cycling.
101
Name a disadvantage for plantrigrade posture?
Limits elongation and mass reduction of distal limbs.
102
Name some advantages for unguligrade posture?
Allows elongation and reduction of distal limb mass.
103
Name a disadvantage of unguligrade posture?
Limits foot rolling and ankle push off.
104
What is the positive and most energetically expensive form of muscle action?
Shortening.
105
What is the negative and most economic, most likely to cause muscle injury form of muscle action?
Lengthening.
106
What are the 3 types of muscle work?
> Shortening.
> Isometric.
> Lengthening.
107
What must happen to resist load?
Contraction.
108
What 2 pieces of information can be used to determine required muscle force?
> Ground forces.
| > Limb posture.
109
What does work equal?
Force x distance.
110
What kind of limbs make better levers?
Longer ones.
111
Does effective mechanical advatage increase or decrease with body size?
It increases with size.
112
How can you reduce muscle force?
developing a high mechanical advantage
113
What happens to posture as an animal gets bigger?
> More upright.
> Longer limbs.
> Straighter limbs.
114
Why must animals change posture and proportion as they get bigger?
Because area increases slower than mass - animals would become weak (strength = cross sectional area)
115
How is energy cost of locomtion measured?
Oxygen uptake.
116
Why do larger animals have a lower cost of transport?
Because they travel a greater distance per stride.
117
What is the metabolically "cheapest" form of exercise?
Swimming
118
What is mechanobiology?
How physical forces and tissue mechanics contribute to development.
119
What is the medullary cavity?
The cavity where bone marrow and trabeculae are found.
120
What does osteoid compose of?
> Type 1 collagen.
> Water.
> Proteoglycans.
121
What does the bone matrix compose of?
> Type 1 collagen.
> Water.
> Proteoglycans.
> Hydroxyapetite mineral.
122
What happens to a primary osteons?
> Increase outside diameter of diaphysis.
> By depositing subperiosteal bone.
> Leaving periosteal blood vessels buried inside osteonal tunnels.
123
What is an osteon?
Basic unit of compact bone.
124
What happens to a secondary osteon?
> Osteoclasts tunnel through bone.
> Followed by osteoblasts which fill in tunnel.
> New haversian canal containing blood vessel formed.
125
What is bone modelling?
Bone deposition with a net change in organ shape.
126
What is bone remodelling?
Bone resorption followed by deposition.
127
How is lamellar bone laid down?
In packets.
128
What is strength?
The stress which a material can bear without failing (measured in gigapascals GPa)
129
What is toughness?
The energy a material can bear without failing (measured in joules per unit)
130
Where is articular cartilage found?
On articulating surfaces of bone.
131
Where are the menisci found?
Tibia of knee joint.
132
What is the miniscus made from?
Fibrocartilage.
133
What is the function of cartilage?
```
> Reduces friction at joints (smooth surface).
> Movement.
> Support (maintains shape).
> Growth (longitudinal growth of bone).
> Load bearing.
```
134
Why is cartilage considered the simplest tissue?
> No blood vessels.
> No nerves.
> Only cells and extracellular matrix.
135
What is cartilage composed of?
> Chondrocytes.
| > EXTRACELLULAR matrix.
136
What is the extracellular matrix of cartilage composed of?
> Type 2 collagen.
> Water.
> Glycosaminoglycans.
> Proteoglycans.
137
What is type 2 collagen made from?
> Type 1 collagen.
| > Elastin.
138
What are the regions of a normal articulating surface?
> Bone/cartilage interface.
> Proliferating region.
> Articulating region.
> Articular surface.
139
What do chondrocytes descend from?
Mesynchymal cells.
140
What is the rate of cell division like for chondrocytes?
Very low.
141
Where do chondrocytes sit?
Within a lacunae.
142
What is the pericellular matrix?
Narrow tissue region surrounding chondrocytes in articular cartilage.
143
What's the function of the pericellular matrix?
Transducer of biochemical and biomechanical signal to the chondrocyte.
144
Describe the structure of type 1 collagen?
Fibrils form fibres.
145
Describe the structure of type 2 collagen?
Fibrils form meshwork.
146
Describe structure of type 3 collagen?
Fibrils form fibres.
147
Describe the structure of type 4 collagen?
Sheet-like network.
148
What is the tidemark of articular cartilage?
Line seperating calcified and non-calcified cartilage.
149
What is the function of proteoglycans within cartilage?
Absorbs and releases water when compressed - helps with shock absorption and articular functions.
150
What's the structure of a proteoglycan aggregate like?
> Core protein.
| > GlycosAminoGlycan (GAG) side chains.
151
What does the fibrous network of collagen provide in cartilage?
> Framework.
> Shape.
> Tensile strength.
152
What does the water within cartilage provide?
> Nutrition.
> Lubrication.
> Weight bearing capacity.
153
What do the proteoglycans within cartilage provide?
> Shock absorption.
| > Resistance to deformation.
154
What are the 3 main types of cartilage?
> Hyaline (including articular).
> Elastic.
> Fibrocartilage.
155
Where is hyaline cartilage found?
> In joints.
> Inside bone as a template for growth.
> In the embryonic skeleton.
156
Where is elastic cartilage found?
> Pinna of ear.
> Auditory canal.
> Larynx.
157
Where is fibrocartilage found?
> Intervertebral disks.
| > Meniscus.
158
Which type of cartilage is the toughest?
Fibrocartilage
159
What's the name of the cells in which all skeletal cells have derived?
Osteochondral progenitor.
160
When does skeletal growth occur?
> Fetal.
> Neonatal.
> Puberty.
161
What are the 3 germ layers?
> Ectoderm.
> Mesoderm.
> Endoderm.
162
Which layer forms the skeleton?
Mesoderm.
163
What cell lineage of the mesoderm did the cranofacial bones derive?
Neural Crest.
164
What cell lineage of the mesoderm did the axial skeleton derive?
Paraxial mesoderm.
165
What cell lineage of the mesoderm did the limb skeleton derive?
Lateral plate mesoderm.
166
What are the 2 ossification processes?
Intramembranous.
| Endochondral.
167
What happens during intramembranous ossification?
Formation of flat bones.
168
What happens during endochondral ossification?
Formation of long bones.
169
What is axial patterning?
Periodic organisation of the vertebral column into multiple vertebrae along the anterior-posterior (AP) axis.
170
What is a somite?
Divisions in the body of an embryo.
171
What does the vertebrate limb develope from?
Limb bud.
172
Describe the limb bud?
A small cluster of mesodermal cells, covered by an ectodermal cup.
173
When does limb formation develope in a chicken embryo?
At 3 days.
174
What happens if the transcription factor twist 1 (plays a role in thumb to fingers development) has a mutation?
Limb abnormalities.
175
What 3 genes play a role in limb development?
> Sonic hedghog (finger formation).
> Twist 1 (finger formation).
> Homeobox (limb dorsal identity).
176
What are the 2 regions where cartilage is not replaced by bone?
> End of epiphysis - joint cartilage.
| > Growth plate.
177
What are the chondrocyte zones?
> Zone of resting cartilage.
> Zone of proliferation.
> Zone of hypertrophy.
> Zone of calcification.
178
What happens to calcified cartilage?
It gets replaced by bone.
179
What 2 vitamins are important for bone growth?
Vitamin C - collagen synthesis.
| Vitamin D - calcium absorption.
180
What hormones are important for bone growth?
> Growth hormone.
> IGF-1.
> Thyroid hormones.
> Estrogen.
181
Why is estrogen important for bone growth?
It closes the growth plate (strengthens bones).
182
What does insefficient growth hormone cause?
Dwarfism.
183
What does excessive growth hormone cause?
Gigantism or acromegaly.
184
What factors increase bone growth?
> Mechanical forces.
> Androgens.
> Parathyroid hormone.
185
What factor decreases bone growth?
Estrogens.
186
What percentage of variation in peak bone mass is due to genetics?
60%
187
What percentage of variation in peak bone mass is due to enviromental factors?
40%
188
Why is it good for the skeleton to have a minimal mass?
For mobility.
189
Why is it good for the skeleton to have optimal strength?
For loading.
190
What are the 2 main processes of bone remodelling?
> Bone resorption.
| > Bone formation.
191
Describe the activity period of bone modelling?
Long time periods:
> Skeletal maturity - 18 years.
> Fracture healing - 1 year.
192
Describe the activity period of bone remodelling?
Short time period:
> Resorption - 3 weeks.
> Formation (deposition) - 13 weeks.
193
Why does bone remodelling happen?
> Release calcium from the skeleton.
> Generate optimum architecture.
> Maintenance - failure prevention.
> Repair micro damage.
194
What is asynchronus?
Not in sync.
195
How is remodelling asynchronus?
It takes place in numerous parts of the skeleton simultaneously.
196
What percentage of the adult skeleton is trabecular bone?
20%
197
What percentage of the adult skeleton is cortical bone?
80%
198
In which (trab or cort) bone does remodelling imbalances happen more frequently?
Trabecular.
199
What are the resorption/reformation zones?
> Resorption - osteoclast cutting tunnel.
> Reversal.
> Formation.
> Resting - osteoblasts finished forming bone.
200
What is mechanosensing?
Responding to mechanical stimuli - such as exercise.
201
What are the 2 specific sites in which bone remodelling targets?
> Sites of fatigue damage.
| > Sites where microcracks are affecting mechanosensing.
202
What happens to osteocytes when fatigue and microcracks happen?
Apoptosis.
203
Why are viable osteocytes necessary?
They prevent osteoclast activation and maintain bone mass.
204
What are inactive osteoblasts called?
Lining cells.
205
What directs bone remodelling?
Osteocytes.
206
How do osteoblasts know when to form new bone?
Apoptopic osteocytes send a signal containing location and size of damage to osteoblasts.
207
What is the 'bone remodelling compartment' ?
Specialized vascular structure including osteoclasts and osteoblasts.
208
What is the 'coupling mechanism' in bone cells?
Osteoclasts sending signals to lining cells
209
What are some features of the 'coupling signal' in bone cells?
> Bi-directional.
| > Stimulated by strain (osteoclasts in response to reduced strain) (Osteoblasts in response to increased strain).
210
What molecules used in the 'coupling signal' between osteoclasts and blasts?
Growth factors.
211
Give another name for osteoprogenitors?
Lining cells.
212
What does the reversal phase do?
It activates the osteoprogenitors.
213
What factors regulate bone remodelling?
> Hormones.
> Cytokines.
> Growth factors.
> Mechanical enviroment.
214
What does parathyroid hormone do?
Regulates calcium and phosphorus concentration in extracellular fluid.
215
What is required for normal matrix mineralisation?
Hormonally active vitamin D.
216
What is calcitonin?
An emergency hormone for osteoclast recruitment.
217
What are the primary effect of estrogen on bone maintenance?
> Promotes osteoclast apoptosis.
> Promotes osteoblast proliferation.
> Promotes osteoblast differentiation.
> Promotes mineralisation of matrix.
218
What happens when estrogen levels drop rapidly (postmenapause)?
Bone density decreases - osteoporosis can develope.
219
What is the major osteoblast stimulating cytokine?
RANK ligand.
220
What changes with age, lead to bone mass loss?
Decline in bone formation.
| Increase in the rate of remodelling.
221
What are the 3 types of muscle?
> Striated (Skeletal).
> Smooth.
> Cardiac.
222
What is a fascicle?
Muscle fibre bundle.
223
What is the perimysium?
Connective tissue between fascicles.
224
What is the epimysium?
Connective tissue on the outside of entire muscle.
225
What is the endomysium?
Connective tissue between individual muscle fibres.
226
Where are capillaries found in muscle?
In the connective tissue.
227
What are the structures within the muscle (largest to smallest)?
> Fascicle.
> Muscle fibre.
> Myofibril.
228
What is a sarcomere?
A structural unit of a myofibril in striated muscle, consisting of a dark band and pale band.
229
What is myosin?
A major contractile protein.
230
What is the structure of myosin like?
Contains:
> Head - consisting of 4 light protein chains.
> Tail - consisting of 2 heavey protein chains.
231
What does myosin do?
Interacts with actin to produce energy.
232
What does the enzyme Myosin ATPase do?
Hydrolyses ATP.
233
What is required for muscle contraction?
Calcium.
234
What is the saroplasmic reticulum?
Type of smooth endoplasmic reticulum that regulates calcium ion concentration in the cytoplasm of striated muscle cells.
235
What happens to calcium as a muscle contracts?
It is released from the saroplasmic reticulum.
236
What happens to calcium as a muscle relaxes?
It returns to the saroplasmic reticulum.
237
What is titin?
It is a highly elastic protein found in a sarcomere.
238
What must happen to proteins actin and myosin for them to contract?
They must interact.
239
What does acetyl choline esterase do?
It brakes down acetyl choline and prevents overstimulation.
240
How do fast muscle fibres appear?
Dark
241
How do slow muscle fibres appear?
Pale
242
What determines muscle fibre type?
Level of activity.
243
How do all muscle fibres in a motor unit contract?
SIMULTANEOUSLY
244
What is a satellite cell?
Precurser to skeletal muscle cells.
245
What do satellite cells do?
Repair.
246
Describe the structure of striated muscle?
Regular arrangement of fibres.
247
Describe the structure of smooth muscle?
Irregular arrangements of fibres.
248
What does troponin and tropomyosin do?
Inhibits actin.
249
What are nerve cells designed for?
To respond to stimuli and transmit information over long distances.
250
What are the 4 functions of neurons?
> Receive information.
> Process information.
> Propagate signal.
> Transmit signal.
251
What are the 3 diffent excitable cells?
> Neurons.
> Muscle cell.
> Endocrine cells.
252
What is an excitable cell?
A cell that can produces an action potential.
253
During resting potential which is more negatively charged inside or outside of cell?
Inside (-70)
254
How much of the body's energy do sodium potassium pumps use?
1/3
255
What is a myotome?
Part of a somite that developes into muscles.
256
What sort of cells align and fuse to make up a myotube?
Myoblasts.
257
What happens to the myotubes?
They gradually differentiate into muscle fibers.
258
What sort of nuclei does developing muscle have?
Central.
259
What sort of nuclei does mature muscle have?
Peripheral.
260
Why is nerve impulse essential for muscle?
It maintains structure and function.
261
What is atrophy?
Wasting away of tissue.
262
What is histochemistry?
Identification of chemical components in cells and tissues.
263
What are nerve cells designed for?
To respond to stimuli and transmit information over long distances.
264
What are the 4 functions of neurons?
> Receive information.
> Process information.
> Propagate signal.
> Transmit signal.
265
What are the 3 diffent excitable cells?
> Neurons.
> Muscle cell.
> Endocrine cells.
266
What is an excitable cell?
A cell that can produces an action potential.
267
During resting potential which is more negatively charged inside or outside of cell?
Inside (-70)
268
How much of the body's energy do sodium potassium pumps use?
1/3
269
Name some features of resting channels?
> Normally open.
> Not influenced by the potential across the membrane.
> Maintain the resting potential.
270
Name some features of gated channels?
> Closed when membrane is at rest.
> Recognise and select specific ions.
> They can open in response to specific signals.
271
Name 3 different type of gated channels?
> Voltage-gated.
> Ligand-gated.
> Mechanically gated.
272
What are the 2 different type of transmembrane potential?
> Local potential - short range
| > Action potential - long range electric signals are propagated along axons.
273
What are the sources of stimulation for local potentials?
> Mechanical - stimulation of gated ion channels (pressure).
| > Chemical - stimulation of ligand-gated ion channels (neurotransmitters)
274
How does depolarization happen?
Voltage-gated sodium channels open.
275
How does hyperpolarization happen?
Voltage-gated potassium and chloride channels open.
276
What are the 3 different types of initiation?
> Stimulation of sensory receptors.
> Synaptic activity (neurotransmitters).
> Spontaneous activity (cardiac).
277
What is the axon hillock?
Region between cell body and axon where many sodium channels are located.
278
What are the 2 different refractory periods?
> Absolute.
| > Relative.
279
What are the 2 types of propagation along an axon?
> Action potential conduction - unmyelinated axons.
| > Saltatory conduction - myelinated axons.
280
What feature of neural transmission ensures conduction only travels in one direction?
Membrane becomes refractory.
281
What are the 3 sites of termination of an action potential?
> Chemical synaps.
> Electrical synaps.
> Neuromuscular junctions.
282
What kicks off the transmission across a synaptic cleft?
Opening of voltage gated calcium channels.
283
What kind of contraction is seen in skeletal muscle?
Voluntary (controlled).
284
What kind of contraction is seen in smooth muscle?
> Involuntary.
| > Voluntary.
285
What kind of contraction is seen in cardiac muscle?
Involuntary.
286
What is the 'somatic nervous system'?
Nerves that serve the skeletal muscles and the exterior sense organs such as the skin.
287
What is a motor unit?
Group of muscle fibres all innervated by the same axon.
288
What is a neuromediator?
A molecule that transports information between neurons - acetylcholine.
289
What does cholinergic mean?
Synthesizes and releases acetylcholine.
290
What is a nicotinic receptor?
> Membrane-spanning protein.
| Formed by 5 protein sub-units.
291
What does a nicotinic receptor do?
> It is binded to by acetylcholine (ligand).
| > Acts as a ligand-gated cation channel for the movement of sodium and potassium.
292
What is the end plate potential?
A depolarizing synaptic potential caused by the influx of Na+ ions.
293
What is sarcolemmal action potential?
Action potential of a muscle.
294
Name 2 presynaptic toxins that prevent the release of acetyle choline?
> Botulinum.
| > Tetanus.
295
What compounds are irreversible antiacetylcholinesterases?
> Organophosphorus.
| > Sarin gas.
296
What are neuromuscular blockers that depolarize the motor end plate used for?
Muscle relaxants - used with anesthesia to produce paralysis.
297
What is Myathenia Gravis?
It is an autoimmune disease in which circulating antibodies block acetyl cholin receptors.
298
What is congenital myasthenia?
Inherited neuromuscular disorder caused by mutation in gene that encodes the muscle acetyl cholin receptor.
299
What is a monosynaptic reflex?
Neural transmission from a sensory neuron to motor neuron across a single synapse (such as knee jerk).
300
What is a polysynaptic reflex?
Neural transmission from a sensory neuron to motor neuron across multiple synapses.
301
What are the different sources of neural delay?
```
> Synaptic delay.
> Nerve conduction delay.
> Neuromuscular junction delay.
> Electromechanical delay.
> Force generation delay
```
302
What does delay limit?
Response time.
303
What is feedforward?
Patterning movement.
304
What is feedback?
Reflex movement.
305
Are larger animals use primarily feedforward or feedback mechanisms?
Feedforward.
306
What is the periosteal reaction?
Formation of new bone in response to injury.
307
What is aerobic scope?
Range of possible oxidative metabolism from rest to maximal exercise.
