Modle 3 - Support And Movement Flashcards
1
Q
Three types of muscle types?
A
Skeletal, Smooth and Cardiac
2
Q
What percentage of body mass does skeletal muscle take up?
A
40-50%
3
Q
What are the characteristics of skeletal muscle?
A
Long and striated with plenty of nuclei
4
Q
What attaches bone to muscle?
A
Tendons
5
Q
Why is a muscle striated in appearance?
A
It is the arrangement of the sarcomeres
6
Q
What part of the central nervous system controls skeletal muscle?
A
The somatic nervous sytem
7
Q
Where is smooth muscle found?
A
GI tract, blood vessels, lymphatic vessels, urinary bladder, reproductive organs/tracts, skin and eyes
8
Q
What does a cardiac muscle look like?
A
Striated, with similar contractile properties to skeletal muscle, but appears to branch (not parallel)
9
Q
What do muscle fibres interconnect at?
A
Intercalated disks
10
Q
Are cardiac muscles uni-nucleate?
A
yes
11
Q
How many muscles in human body?
A
Roughly 320 on either side
12
Q
Where is the Muscle-Tendon origin and insertion usually?
A
Origin is proximal, insertion is distal
13
Q
Four main functions of muscles?
A
Contractility, excitability, extensibility, elasticity
14
Q
What is excitability (muscle)
A
Ability to respond to appropriate stimuli
15
Q
What is extensibility (muscle)?
A
Ability to be stretches without damage
16
Q
What is elasticity (muscle)?
A
Ability to store some energy, recoil to the resting length
17
Q
What us contractility (muscle)?
A
Ability to shorten and thicken, and develop tension
18
Q
Where are the contractile filaments of a muscle that convert action potentials found?
A
Within the myofibrils
19
Q
When a muscle shortens, what happens to the filaments and z line? How about when it lengthens?
A
The muscle shortens asa result to the filaments overlapping more, pulling the z lines closer. When it lengthens, the filaments overlap less
20
Q
What anchors myosin to the z line?
A
Titin
21
Q
What does Titin contribute to in muscles?
A
Passive force
22
Q
Diameter of myosin and actin?
A
16nm and 8nm respectively
23
Q
Action of a muscle shortening at the myosin/actin sites is called:?
A
A power stroke
24
Q
Four main types of tissues within the body?
A
Epithelial, muscle, nervous and connective
25
Most common type of tissue in the body?
Connective
26
Define tissues
Groups of similar cells and their extracellular products, organised to perform a common function
27
Do muscle cells have an ECM?
Barely anymore, it is surrounded by connective tissue for the most part, which in turn has more a significant ECM
28
Order of connective tissue in a muscle cell?
Epimysium, Perimysium, Endomysium
29
What does epimysium do?
Fibrous tissue that surrounds skeletal muscle
30
What does perimysium do?
Groups muscle fibres into a fascicle
31
What does endomysium do?
Surrounds each muscle fibre
32
What does a motor unit consist of?
1 motor neuron, its motor axon and all of the uscle fibres it innervates
33
Three types of skeletal muscle fibres?
Type 1: Slow oxidative
Type 2a: Fast oxidative
Type 2b: Fast glycolytic
34
Myoglobin content of the three skeletal muscle fibres?
Type 1: (high) Red
Type 2a: (high) Red
Type 2b: (low) White
35
Mitochondria count in skeletal muscle fibres?
Type 1: Many
Type 2a: Many
Type 2b: Few
36
Rate of fatigue within muscle fibres?
Type 1: Slow
Type 2a: Intermediate
Type 2b: Fast
37
Major ATP sources in skeletal muscle fibres?
Type 1: Aerobic respiration
Type 2a: Aerobic respiration
Type 2b: Glycolysis
38
Where are most slow twitch fibres found in concentration?
Frontalis, Peroneus Longus (calf) and Biceps Femoris
39
What is a hydrostatic skeleton?
Fluid held under pressure (like in worms)
40
Four basic roles of our skeletal structure?
Support, protection, movement and metabolic functions
41
What percentage of the body’s calcium and phosphorus does the human body store in its bones?
99% of calcium and 85% of phosphorus
42
Two segment of adult skeleton?
Axial and Appendicular
43
What is the axial skeleton in relation to?
Head and trunk region
44
What is the appendicular skeleton?
In relation to limbs
append - to add something to the end
45
How many bones in adult skeleton?
206
46
How many bones in axial skeleton?
80
47
How many bones in the skull?
22
48
Name of bone in middle ear?
Ossicle
49
What s the bone that aids the tongue in movement?
Hyoid
50
How many bones in appendicular skeleton?
126
51
Four main anatomical planes?
Sagittal, parasagittal, coronal and transverse
52
Flexion and extension of the foot at the ankle is referred to as:
Dorsiflexion and plantarflexion
53
Three types of joints?
Fibrous, cartilaginous and synovial
54
What are fibrous joints?
Contain fibrous connective tissue and allow very little movement. *ie skull or ankle
55
What are cartilaginous joints?
Contain cartilage that cushions forces. Allows a little movement. *ie pelvic girdle, intervertebral discs
56
What are synovial joints?
Only joint that has a space (filled with fluid) that allows for greatest range of movement *ie knee, elbow
57
What connects bone to bone?
Cartilage and ligaments
58
Six types of joint movements?
```
Pivot joint
Hinge joint
Saddle join
Plane joint
Condyloid joint
Ball-and-socket joint
```
59
What joint is found between tarsal bones?
Plane joint
60
What joint is found between the trapezium carpal bone and 1st metacarpal bone?
Saddle joint
61
What joint is found in the hip?
Ball and socket
62
What joint is found in the elbow?
Hinge
63
What joint is found in the neck (c1 and c2)?
Pivot
64
What joint is found between the radius and carpal bones of the wrist?
Condyloid joint
65
Antagonist of masseter/temporalis?
Masseter/temporalis - jaw closer
Giastric - jaw opener
66
Antagonist of rectus abdominis?
Eractor spinae
67
Antagonist of tibialis anterior?
Soleus
68
What do synergist muscles do?
Help perform the same joint motion (as agonist muscles)
69
Four types of bone?
Long, short, flat and irregular
70
What type of bones are caprals and tarsals?
Short
71
What type of bone is the sesamoid bone?
short
72
What type of bone are ribcages?
flat
73
What bones produce blood?
Flatand irregular
74
What is the term for blood production?
Hematopoiesis
75
What type of bone is the pelvis?
Irregular
76
Percentage of bone that is collagen?
40%
77
Percentage of bone that is calcium and salts?
60%
78
What provides the hardness and rigidity of a bone?
The calcium and alts
79
What does collagen do to a bone?
Provides toughness and flexibility
80
Where is calcium and salts found in bone?
Between the collagen fibres
81
How is collegan fibre in bones in children presented?
They are randomly distributed compared to a mature bone
82
Four types of bone cells?
Osteoclasts, osteoblasts, osteocytes and osteogenic cells
83
What are osteoclasts? (Four main points)
Very large cell with many nuclei thought to:
1. Improve reabsorption efficiency
2. Breakdown one matrix
3. Destroy and reabsorb bone
4. Respond to mechanical stress
84
What are dig tunnels line with in bone?
With collagen by the Osteoblasts
85
What are osteoblasts? (4 points)
Located on the surface of the bone, they:
1. Line tunnels with collagen
2. Create bone matrix
3. Build bone
4. Differentiate into osteocytes when trapped in bone
86
What are osteocytes? (Four things)
Long cytoplasmic extensions that:
1. Maintain bone matrix
2. Hold bone together
3. Mineralise the bone matrix (calcium and salts)
4. Supply nutrients into the bone matrix
87
What are osteogenic cells?
Stem cells that develop into an osteoblast (to form bone) and then an osteocyte (to maintain bone)
88
What is the ECM composed of in tissues?
Proteins, salts, H2O and dissolved macromolecules
89
Two types of bone?
Traecular (spongy bone)
Compact (lamellar or cortical bone)
90
What is trabecular bone?
Greater surface area compared to compact bone
Promotes bone marrow to develop (produces red blood cels and lymphocytes, support the immune system).
Trabeculae form along lines of stess
91
What is compact bone?
Hard, dense bone
Support the body, stores calcium
Organised structure
92
How does a bone grow or remodel?
In response to the forces applied upon it
93
Where are long bones the thickest?
Along the shaft
94
How does handedness play a role in bone thickness?
Right or left hand that dominates tends to be thicker
95
Why is the shaft (long part) of the bone the thickest?
Bending stress is the greatest
96
Which bones are most likely to be at their thickest?
Where heavy, active muscles attach - where they are most likely to buckle
97
How many ossification centres in a foetus? (11 weeks prior to birth)
800
98
How many ossification centres in a neonate (new born)?
450
99
What ratio of skeleton is cartilaginous in neonates?
2/3rds
100
What percentage of skeleton in an adult is cartilaginous?
10%
101
What process does long bone develop through?
Endochondral ossification
102
What precedes bone formation?
Crtlagnoustissue
103
When can primary ossification centres be found?
8 weeks after fertilisation
104
When are secondary ossification centres found?
They are present after birth until growth stops
105
Stages of bone development
```
Resting cartilage
Cartilage proliferation
Cartilage maturation
Cartilage calcification
Ossification
```
106
What is the spongy bone?
Trabecular
107
What forms along lines of stress?
Trabeculae
108
What are the types of muscle fibre directions?
```
Circular
Convergent
Unipennate
Bipennate
Parallel-non-fusiform
Parallel-fusiform
Mutlipennate
```
109
What is the difference between parallel-fusiform and parallel-non-fusiform?
Parallel-fusiform gets bigger in the middle, whereas the non-fusiform doesn’t
110
What can circular muscles do?
Close an opening
111
What are long and short muscles good at?
Long muscles are better at controlling movement over joints that have a large range of motion.
Shorter, wider muscles are better at generating larger forces over a smaller range of motion
112
What is PCSA?
Physiological cross section area
113
What is the simple calculation for PCSA?
PCSA = Muscle Volume/Fibre Length
114
What is the greatest predictor of force capacity?
The muscles physiological cross sectional area
115
What is muscle force influenced by? (4)
Muscle architecture
Sarcomere length
Single motor unit
Type of contraction
116
Three components of Hill’s mechanical model of muscle-tendon unit?
Contractile Component (CC)
Series Elastic Component (SEC)
Parallel Elastic Component (PEC)
117
What composes the contractile component?
Muscle fibres, actin and myosin cross bridges
118
What composes the series elastic component?
Intracellular titin and tendons
119
What composes the parallel elastic component?
Connective tissues and passive cross bridge connections
120
What are the three types of connective tissues?
Epimysium, perimysium and endomysium
121
Optimal sarcomere operating length?
80-120% of resting length
122
What does elasticity refer to?
It describes the tendency of a material to revert to its previous shape after deformation;
123
What is the smallest functional unit in the musculoskeletal system?
The single motor unit
124
What is force altered by in muscle contractions?
The NUMBER and DISCHARGE RATE of motor units
125
What is force influenced by?
The number of different motor units that are discharging
126
What is used to record a myo-electric action potential?
A EMG
127
How many muscle fibres per motor unit in the eye?
6
128
How many muscle fibres per motor unit in the quadriceps?
Roughly 2000
129
What is the neuromuscular junction?
The connection between the nervous system and the muscle
130
Other words for a neuromuscular junction?
Motor point, motor end plate, synatic cleft and synaptic terminal
131
What neurotransmitter is released at the synaptic terminal?
Acetylcholine
132
How is a myoelectric action potential triggered at the synaptic terminal?
By aCh binding to proteins on muscle cell membrane (G-Protein response)
133
During a myoelectric action potential, where does the action potential sweep along into?
It sweeps along the mucle fibre into transverse (T) tubules
134
Where is Ca2+ released from in an action potential?
The SR (Sarcoplasmic reticulum)
135
What do calcium ions bind to in thin filament?
Troponin
136
What happens once calcium ions bind to troponin during an action potential?
Myosin-binding sites are exposed
137
What two processes slide thin filaments towards the centre of a sarcomere?
Cycles of myosin cross-bridge formation and breakdown
Coupled with ATP hydrolysis
138
What removes Cytosolic Ca^2+ after an action potential ends?
Cytosolic CA^2+is removed by active transport into SR via a Ca^2+ pump
139
What is the final step of a muscle contraction following an action potential?
Tropomyosin blockage of myosin-binding sites is restored, contraction ends, and muscle fibres relax
140
What does a surface electromyography record?
The myoelectrical action potentials that are running along the muslce fibresunder the electrodes
141
Six physiological factors that influence muscle force
1. Muscle physiological cross-sectional area
2. Pennation angle of muscle fibres
3. Sarcomere length
4. Type of contraction
5. Number
142
What is an atom?
Smallest unit of masure
143
What is a molecule?
Two or more atoms
144
What is a macromolecule?
More complex molecules (Protein, dNA) combining together to form organelles
145
Four types of tissues?
Epithelial
Nervous
Muscle
Connective
146
Wha is the study of tissues?
Histology
147
What percentage of body weight do nerves take??
~3%
148
What muscles move the food along the digestive tract?
Peristalsis
149
What characteristics define connective tissue?
Few cells + an extensive ECM
150
Where is fibrous connective tissue found?
In tendons ad ligaments
151
What is fibrous connective tissue? How is it structures?
Dense bundles of collagen fibres. Collagen generally lies in parallel.
152
What does fibrous connective tissue do?
Provides shock absorption
Limits range of motion
Transmits force from muscle to bone
153
What is cartilage? Where is it found?
Smooth elastic connective tissue.
Covers and protects the ends of long bones at the joints, but always found between the ribs, in the ear, nose etc
154
What are cartilage cells called?
Chondrocytes
155
What do chondrocytes secrete? What does this do?
They secrete collagen and other substances to make tissue strong and flexible
156
What happens to most cartilage during development and maturity?
It is replaced by bone
157
What type of tissue is bone?
Connective tissue
158
What cells deposit collagen?
Osteoblasts
159
What cells maintain the matrix with calcium and salts?
Osteocytes
160
What are osteons?
Concentric layers of the mineralised matrix around blood vessels in compact bone
161
What is the integumentary system?
Skin and its derivatives (hair, claws, skin glands)
162
What is peak height velocity?
The period where maximum rate of growth occurs during adolescence
163
what is the strongest indicator of risk of osteoporosis?
Bone acquisition during childhood and adolescence
164
How does bone develop in foetuses?
Cartilaginous tissue precedes bone formation
Primary ossification centres form ~8 weeks after fertilisation
165
What are the areas of a bone to start developing?
Primary ossification centres
166
Stages of bone development?
1. Cartilage cell increase in cell number and size
2. Tissue is calcified
3. Tissue is invaded by nutrients and osteoblasts
4. Osteoclasts remodel the internal structure
167
What is the outer layer of bone called?
Harder external cortex
168
What is the less dense internal region of bone?
Hollow structure
169
In regards to weight and strength, what is a bone?
Light and strong
170
How do bones develop?
Via endochondral ossification
171
When are secondary ossification centres present?
After birth until growth stops
172
Where can all stages of bone development be seen?
In a growth (epiphyseal) plate
173
Stages of development in an epiphyseal plate?
```
Resting cartilage
Cartilage proliferation
Cartilage maturation
Cartilage calcification
Ossification
```
174
What is a sign ossification has occured?
Osteoblasts forming bone
175
What is a sign cartilage calcification has occurred?
Extracellular matrix becomes calcified
176
What is a sign of cartilage maturation?
Hypertrophy
177
What is asign of cartilage proliferation?
Hyperplasia
178
Where are curved bones thickest?
Where they are most likely to buckle
179
Where are long bones thickest?
Midway down the shat
180
Where are bony projections found?
Where heavy, active muscles attach
181
Where do lines of stress form in the bone?
On the trabeculae
182
What happens to trabecular during decay?
A decrease in the number of traberculae (“small rods”)
183
How is a muscle fibre formed?
A fibre is made from a large number of fused embroyonic cells (myoblasts)
184
Why does a muscle have multiple nuclei?
For it is formed from multiple embryonic cells (myoblasts)
185
What are satellite cells?
Stem cells that can differentiate into myoblasts and sit within the endomysium
186
When do myoblasts fuse to other muscle cells?
During growth and repair throughout the life-span
187
What are satellite cells most important for during maturation?
Hypertrophy
188
What do myoblasts cells do in utero?
Elongate and aggregate into bundles. They fuse longitudinally and form the multinucleated fibres (myotubes)
189
When do myoblasts become striated in utero?
Striated by the 3rd month of development
190
How are myotubes formed?
By fusion of myoblasts
191
When do our muscles start producing force?
12 weeks1
192
Total weight of infant that is muscle?
~25%
193
Total weight of adult Male (20 yrs) that is muscle? What about female?
~40%, female roughly 30-35%
194
Contraction speed of slow oxidative muscle fibre?
Slow
195
Contraction speed of fast oxidative muscle fibre?
Fast
196
Contraction speed of fast glycolytic muscle fibre?
Fast
197
Major ATP source of slow oxidative muscle fibre?
Aerobic respiration
198
Major ATP source of fast oxidative muscle fibre?
Aerobic respiration
199
Major ATP source of fast glycolytic muscle fibre?
Glycolysis
200
Rate of fatigue of slow oxidative muscle fibre?
Slow
201
Rate of fatigue of fast oxidative muscle fibre?
Interediate
202
Rate of fatigue of fast glycolytic muscle fibre?
Fast
203
Mitochondria count of slow oxidative fibres?
Many
204
Mitochondria count of fast oxidative fibres?
Many
205
Mitochondria count of fast glycolytic fibres?
Few
206
Myoglobin content of slow oxidative fibres?
High (red muscle)
207
Myoglobin content of fast oxidative fibres?
High (red muscle)
208
Myoglobin content of fast glycolytic fibres?
Low (white muscle)
209
Can an ultrasound give information about fibre types?
No
210
Two types of input to motorneuron in the spinal cord?
Excitatory and inhibitory inputs
211
Where do excitatory and inhibitory inputs generate?
Excitatory and inhibitory post synaptic potentials (EPSP and IPSP’s)
212
Motor areas of the brain?
Brain stem and cerebellum
213
What does the brain stem for for motor control?
Basic movement and posture
214
What does the cerebellum for for motor control?
Refining information
215
What does the spinal cord do in regards to motor control?
Reflex activity (involuntary movement)
216
Steps of using ATP during skeletal muscle contraction?
1. Contraction begins when ATP is hydrolosyed to create ADP and an inorganic phosphate
2. This energy allows the myosin head to extend and attach to a binding site on the actin forming a cross bridge
3. Allowing the power stroke. Pulling of actin across myosin. Shortening the sacromere
4. ADP and inorganic phosphate are released during power stroke
5. Myosin remains attached to actin (in a lo energy state until a new ATP molecule binds
217
What are the three types of connective tissue?
Collagenous fibres
Reticular fibres
Elastic fibres
218
What do collagenous fibres do?
Provide strength and flexibility
219
What do reticular fibres do?
Join connective tissue to adjacent tissues
220
What do elastic fibres do?
Make tissue elastic
221
When you pinch the skin on the back of your hand, how do the three connective tissues work together?
The collagenous and reticular fibres prevent the skin from being pulled far from the bone, while the elastic fibres restore it back to its place.
222
What is the most widesead connective tissue in the vertebrate body?
Loose connective tissue
223
What does loose connective tissue do? Where is it found?
Binds epithelia to underlying tissues and holds organs in place. Found in the skin and throughout the body
224
Where does loose connective tissue get its name from?
The loose weave of its fibres
225
What is fibrous connective tissue? Where is it found?
Tissue dense with collagenous fibres. Found in tendons and ligaments.
226
What connects bone to bone?
Ligaments
227
What connects muscles to bone?
Tendons
228
What repeating units form the concrete structure of bone?
Osteons
229
What is the energy storage cell?
Adipose
230
What does cartilage consist of?
Collagenous fibres embedded in a rubbery protein-carbohydrate complex
231
In cartilage, what is the rubbery protein-carbohydrate complex called?
The chondroitin sulphate
232
What cells are found in a chondroitin sulphate?
Chondrocytes
233
What do chondrocytes do?
Secrete the collagen and chondroitin sulphate, which together make a strong yet flexible supportive material.
234
What cell shape are smooth muscle?
Striated and spindle shaped
235
What muscle types are voluntary and involuntary?
Muscle = V
Smooth Muscle = IV
Cardiac Muscle = IV
236
How does cardiac muscles connect? What does this achieve?
Via intercalated disks, which relay signals from cell to cell and help synchronise heart contractions
237
What do glial cells do?
Help nourish, insulate and replenish neurons. In some cases modulate neuron functioning.
238
What junctions are found between nerves?
Gap junctions
239
What do neurotrasmitters package into at the presynaptic neuron?
Synaptic vessicles
240
What is the distance of the synaptic cleft typically?
50nm
241
What is a ligan-gated ion channel also called?
Ionotrpic receptor
242
What can a hypolarisation that occurs at the postsynaptic membrane result in? Why?
A inhibitory postsnaptic potential, because it moves the membrane potential further from theshold
243
What occurs when two ESPS signals happen in rapid summation?
Temporal summation
244
What occurs when two different sources of postsynaptic neurons occur simultaneously?
Spatial summation
245
In G-protein responses, what does the neurotrasmitter bind to?
A metabotropic receptor
246
What enzyme terminates acetylcholine?
Acetylcholinesterase
247
What is the effect of acetylcholine in the heart? Why does this occur?
Inhibitory rather than excitatory. In the heart, acetylcholine released by neurons activates a signal transduction pathway.
The G proteins in the pathway inhibit adenylyl cyclase and open potassium channels in the muscle cell membrane. Both effects reduce the rate at which the heart pumps.
248
Two major classes of aetylcholine receptors?
One is a ligand-gated ion channel, other is ionotropic found in the CNS and PNS
249
Most common neurotrasmitter in the CNS of vertebrates?
Glutamate
250
Difference between vertebrates and invertebrates at the neuromuscular junction?
Invertebrates use glatamate instead of acetylcholine
251
What is the neurotransmitter at most inhibitory synapses in the brain?
Gama-aminobutyric acid (GABA)
252
What does binding of GABA to receptors in postsynaptic cells result in?
Permeability to Cl-, resulting in an IPSP
253
What does vallium bind to?
A GABA receptor in the brain (causing IPSP)
254
What does nicotine bind to?
A ionotropic receptor that acetylcholine binds to, resulting in physiological and psychological stimulaton
255
Five types of neurotransmitters?
```
Acetylecoline
Amino acids
Biogenic Amines
Neuropeptides
Gases
```
256
Most diverse group of neurotransmitters?
Neuropeptides
257
What type of neurotransmitter is nonadreneline?
A biogenic amine
258
What do depression drugs usually focus on? (What type of neurotransmitter?)
Increasing brain concentrations of biogenic amines
259
How does prozac work?
It enhances the effect of serotonin by inhibiting its reuptake after release
260
How does botox work?
By blocking transmission at synapses (inhibiting acetylcholine) of particular face muscles
261
What are neuropeptides?
Relatively short chains of amino acids that serve as neurotransmitters and operate via metabotropic receptors
262
Key neurotransmitter of pain? What type os neurotransmitter is it?
Substance P - a neuropeptide
263
What decrease pain reception?
Endorphins
264
In addition to decreasing pain, what do endorphins do?>
Reduce urine output, decrease respiration, produce euphoria and stimualte good emotions
265
How do opiates work?
By binding to same receptors as endorphins
266
How do males become erect?
By release of nitric oxide into tissue of penis
267
How does viagra work?
By inhibiting an enzyme that terminates the action of nitric oxide
268
How is nitric acid stored? (As a neurotransmitter)
It’s not stored, but synthesised on demand
269
Can CO work as a neurotransmitter? How?
In the brain, CO regulates the release of hypothalamic hormones. In the PNS, it acts as an inhibitory neurotransmitter that hyperpolarises the plasma membrane of intestinal smooth muscle cells.
270
If you were to inhibit acetylcholinesterase, what would happen to the EPSP produced by acetylcholine?
They would remain for longer since the neurotransmitter would remain longer in the synaptic cleft
271
Three membrane activites that occur both in fertilisation of an eff and in neutrotransmission across a synapse?
Membrane depolarisation
Exocytosis
Membrane fusion
272
Major component of thin filaments? What type of protein is it?
Globular protein actin
273
What type of molecules make up thick filaments?
Myosin molecules
274
What gives skeletal muscle its striated appearance?
The borders of the sarcomeree line up in adjacent myofibrils, forming a pattern of light and dark band (striatations) visible with a light microscope
275
What does calcium bind to in the sacromere?
Troponin
276
What does tropomyosin do to myosin?
Blocks the myosin head
277
How does calcium move tropomoyosin out of the way?
By binding to troponin and it then moves tropomyosin out of the way
278
How does tropomyosin disconnect from myosin?
Low calcium makes troponin go back to its standard configuration and makes tropomyosin block the myosin head once again
279
Difference between afferent and efferent?
Afferent takes information to the cns
Efferent is the effector (to the muscles)
280
In the animal cell, what part of cytoskeleton does not contribute to motility?
Out of microtubules, intermediate filaments and microfilaments, intermediate filaments (fibrous proteins) play no part
281
Percentage of body weight that is bone?
15%
282
Difference between compact and cancellous bone?
Compact bones are made of osteons while spongy bones are made of trabeculae.
Compact bones are tough and heavy while spongy bones are light.
Compact bones fill the outer layer of most of the bones while spongy bones fill the inner layer of the bones
