Modle 3 - Support And Movement Flashcards
Three types of muscle types?
Skeletal, Smooth and Cardiac
What percentage of body mass does skeletal muscle take up?
40-50%
What are the characteristics of skeletal muscle?
Long and striated with plenty of nuclei
What attaches bone to muscle?
Tendons
Why is a muscle striated in appearance?
It is the arrangement of the sarcomeres
What part of the central nervous system controls skeletal muscle?
The somatic nervous sytem
Where is smooth muscle found?
GI tract, blood vessels, lymphatic vessels, urinary bladder, reproductive organs/tracts, skin and eyes
What does a cardiac muscle look like?
Striated, with similar contractile properties to skeletal muscle, but appears to branch (not parallel)
What do muscle fibres interconnect at?
Intercalated disks
Are cardiac muscles uni-nucleate?
yes
How many muscles in human body?
Roughly 320 on either side
Where is the Muscle-Tendon origin and insertion usually?
Origin is proximal, insertion is distal
Four main functions of muscles?
Contractility, excitability, extensibility, elasticity
What is excitability (muscle)
Ability to respond to appropriate stimuli
What is extensibility (muscle)?
Ability to be stretches without damage
What is elasticity (muscle)?
Ability to store some energy, recoil to the resting length
What us contractility (muscle)?
Ability to shorten and thicken, and develop tension
Where are the contractile filaments of a muscle that convert action potentials found?
Within the myofibrils
When a muscle shortens, what happens to the filaments and z line? How about when it lengthens?
The muscle shortens asa result to the filaments overlapping more, pulling the z lines closer. When it lengthens, the filaments overlap less
What anchors myosin to the z line?
Titin
What does Titin contribute to in muscles?
Passive force
Diameter of myosin and actin?
16nm and 8nm respectively
Action of a muscle shortening at the myosin/actin sites is called:?
A power stroke
Four main types of tissues within the body?
Epithelial, muscle, nervous and connective
Most common type of tissue in the body?
Connective
Define tissues
Groups of similar cells and their extracellular products, organised to perform a common function
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
Order of connective tissue in a muscle cell?
Epimysium, Perimysium, Endomysium
What does epimysium do?
Fibrous tissue that surrounds skeletal muscle
What does perimysium do?
Groups muscle fibres into a fascicle
What does endomysium do?
Surrounds each muscle fibre
What does a motor unit consist of?
1 motor neuron, its motor axon and all of the uscle fibres it innervates
Three types of skeletal muscle fibres?
Type 1: Slow oxidative
Type 2a: Fast oxidative
Type 2b: Fast glycolytic
Myoglobin content of the three skeletal muscle fibres?
Type 1: (high) Red
Type 2a: (high) Red
Type 2b: (low) White
Mitochondria count in skeletal muscle fibres?
Type 1: Many
Type 2a: Many
Type 2b: Few
Rate of fatigue within muscle fibres?
Type 1: Slow
Type 2a: Intermediate
Type 2b: Fast
Major ATP sources in skeletal muscle fibres?
Type 1: Aerobic respiration
Type 2a: Aerobic respiration
Type 2b: Glycolysis
Where are most slow twitch fibres found in concentration?
Frontalis, Peroneus Longus (calf) and Biceps Femoris
What is a hydrostatic skeleton?
Fluid held under pressure (like in worms)
Four basic roles of our skeletal structure?
Support, protection, movement and metabolic functions
What percentage of the body’s calcium and phosphorus does the human body store in its bones?
99% of calcium and 85% of phosphorus
Two segment of adult skeleton?
Axial and Appendicular
What is the axial skeleton in relation to?
Head and trunk region
What is the appendicular skeleton?
In relation to limbs
append - to add something to the end
How many bones in adult skeleton?
206
How many bones in axial skeleton?
80
How many bones in the skull?
22
Name of bone in middle ear?
Ossicle
What s the bone that aids the tongue in movement?
Hyoid
How many bones in appendicular skeleton?
126
Four main anatomical planes?
Sagittal, parasagittal, coronal and transverse
Flexion and extension of the foot at the ankle is referred to as:
Dorsiflexion and plantarflexion
Three types of joints?
Fibrous, cartilaginous and synovial
What are fibrous joints?
Contain fibrous connective tissue and allow very little movement. *ie skull or ankle
What are cartilaginous joints?
Contain cartilage that cushions forces. Allows a little movement. *ie pelvic girdle, intervertebral discs
What are synovial joints?
Only joint that has a space (filled with fluid) that allows for greatest range of movement *ie knee, elbow
What connects bone to bone?
Cartilage and ligaments
Six types of joint movements?
Pivot joint Hinge joint Saddle join Plane joint Condyloid joint Ball-and-socket joint
What joint is found between tarsal bones?
Plane joint
What joint is found between the trapezium carpal bone and 1st metacarpal bone?
Saddle joint
What joint is found in the hip?
Ball and socket
What joint is found in the elbow?
Hinge
What joint is found in the neck (c1 and c2)?
Pivot
What joint is found between the radius and carpal bones of the wrist?
Condyloid joint
Antagonist of masseter/temporalis?
Masseter/temporalis - jaw closer
Giastric - jaw opener
Antagonist of rectus abdominis?
Eractor spinae
Antagonist of tibialis anterior?
Soleus
What do synergist muscles do?
Help perform the same joint motion (as agonist muscles)
Four types of bone?
Long, short, flat and irregular
What type of bones are caprals and tarsals?
Short
What type of bone is the sesamoid bone?
short
What type of bone are ribcages?
flat
What bones produce blood?
Flatand irregular
What is the term for blood production?
Hematopoiesis
What type of bone is the pelvis?
Irregular
Percentage of bone that is collagen?
40%
Percentage of bone that is calcium and salts?
60%
What provides the hardness and rigidity of a bone?
The calcium and alts
What does collagen do to a bone?
Provides toughness and flexibility
Where is calcium and salts found in bone?
Between the collagen fibres
How is collegan fibre in bones in children presented?
They are randomly distributed compared to a mature bone
Four types of bone cells?
Osteoclasts, osteoblasts, osteocytes and osteogenic cells
What are osteoclasts? (Four main points)
Very large cell with many nuclei thought to:
- Improve reabsorption efficiency
- Breakdown one matrix
- Destroy and reabsorb bone
- Respond to mechanical stress
What are dig tunnels line with in bone?
With collagen by the Osteoblasts
What are osteoblasts? (4 points)
Located on the surface of the bone, they:
- Line tunnels with collagen
- Create bone matrix
- Build bone
- Differentiate into osteocytes when trapped in bone
What are osteocytes? (Four things)
Long cytoplasmic extensions that:
- Maintain bone matrix
- Hold bone together
- Mineralise the bone matrix (calcium and salts)
- Supply nutrients into the bone matrix
What are osteogenic cells?
Stem cells that develop into an osteoblast (to form bone) and then an osteocyte (to maintain bone)
What is the ECM composed of in tissues?
Proteins, salts, H2O and dissolved macromolecules
Two types of bone?
Traecular (spongy bone)
Compact (lamellar or cortical bone)
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
What is compact bone?
Hard, dense bone
Support the body, stores calcium
Organised structure
How does a bone grow or remodel?
In response to the forces applied upon it
Where are long bones the thickest?
Along the shaft
How does handedness play a role in bone thickness?
Right or left hand that dominates tends to be thicker
Why is the shaft (long part) of the bone the thickest?
Bending stress is the greatest
Which bones are most likely to be at their thickest?
Where heavy, active muscles attach - where they are most likely to buckle
How many ossification centres in a foetus? (11 weeks prior to birth)
800
How many ossification centres in a neonate (new born)?
450
What ratio of skeleton is cartilaginous in neonates?
2/3rds
What percentage of skeleton in an adult is cartilaginous?
10%
What process does long bone develop through?
Endochondral ossification
What precedes bone formation?
Crtlagnoustissue
When can primary ossification centres be found?
8 weeks after fertilisation
When are secondary ossification centres found?
They are present after birth until growth stops
Stages of bone development
Resting cartilage Cartilage proliferation Cartilage maturation Cartilage calcification Ossification
What is the spongy bone?
Trabecular
What forms along lines of stress?
Trabeculae
What are the types of muscle fibre directions?
Circular Convergent Unipennate Bipennate Parallel-non-fusiform Parallel-fusiform Mutlipennate
What is the difference between parallel-fusiform and parallel-non-fusiform?
Parallel-fusiform gets bigger in the middle, whereas the non-fusiform doesn’t
What can circular muscles do?
Close an opening
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
What is PCSA?
Physiological cross section area
What is the simple calculation for PCSA?
PCSA = Muscle Volume/Fibre Length
What is the greatest predictor of force capacity?
The muscles physiological cross sectional area
What is muscle force influenced by? (4)
Muscle architecture
Sarcomere length
Single motor unit
Type of contraction
Three components of Hill’s mechanical model of muscle-tendon unit?
Contractile Component (CC)
Series Elastic Component (SEC)
Parallel Elastic Component (PEC)
What composes the contractile component?
Muscle fibres, actin and myosin cross bridges
What composes the series elastic component?
Intracellular titin and tendons
What composes the parallel elastic component?
Connective tissues and passive cross bridge connections
What are the three types of connective tissues?
Epimysium, perimysium and endomysium
Optimal sarcomere operating length?
80-120% of resting length
What does elasticity refer to?
It describes the tendency of a material to revert to its previous shape after deformation;
What is the smallest functional unit in the musculoskeletal system?
The single motor unit
What is force altered by in muscle contractions?
The NUMBER and DISCHARGE RATE of motor units
What is force influenced by?
The number of different motor units that are discharging
What is used to record a myo-electric action potential?
A EMG
How many muscle fibres per motor unit in the eye?
6
How many muscle fibres per motor unit in the quadriceps?
Roughly 2000
What is the neuromuscular junction?
The connection between the nervous system and the muscle
Other words for a neuromuscular junction?
Motor point, motor end plate, synatic cleft and synaptic terminal
What neurotransmitter is released at the synaptic terminal?
Acetylcholine
How is a myoelectric action potential triggered at the synaptic terminal?
By aCh binding to proteins on muscle cell membrane (G-Protein response)
During a myoelectric action potential, where does the action potential sweep along into?
It sweeps along the mucle fibre into transverse (T) tubules
Where is Ca2+ released from in an action potential?
The SR (Sarcoplasmic reticulum)
What do calcium ions bind to in thin filament?
Troponin
What happens once calcium ions bind to troponin during an action potential?
Myosin-binding sites are exposed
What two processes slide thin filaments towards the centre of a sarcomere?
Cycles of myosin cross-bridge formation and breakdown
Coupled with ATP hydrolysis
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
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
What does a surface electromyography record?
The myoelectrical action potentials that are running along the muslce fibresunder the electrodes
Six physiological factors that influence muscle force
- Muscle physiological cross-sectional area
- Pennation angle of muscle fibres
- Sarcomere length
- Type of contraction
- Number
What is an atom?
Smallest unit of masure
What is a molecule?
Two or more atoms
What is a macromolecule?
More complex molecules (Protein, dNA) combining together to form organelles
Four types of tissues?
Epithelial
Nervous
Muscle
Connective
Wha is the study of tissues?
Histology
What percentage of body weight do nerves take??
~3%
What muscles move the food along the digestive tract?
Peristalsis
What characteristics define connective tissue?
Few cells + an extensive ECM
Where is fibrous connective tissue found?
In tendons ad ligaments
What is fibrous connective tissue? How is it structures?
Dense bundles of collagen fibres. Collagen generally lies in parallel.
What does fibrous connective tissue do?
Provides shock absorption
Limits range of motion
Transmits force from muscle to bone
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
What are cartilage cells called?
Chondrocytes
What do chondrocytes secrete? What does this do?
They secrete collagen and other substances to make tissue strong and flexible
What happens to most cartilage during development and maturity?
It is replaced by bone
What type of tissue is bone?
Connective tissue
What cells deposit collagen?
Osteoblasts
What cells maintain the matrix with calcium and salts?
Osteocytes
What are osteons?
Concentric layers of the mineralised matrix around blood vessels in compact bone
What is the integumentary system?
Skin and its derivatives (hair, claws, skin glands)
What is peak height velocity?
The period where maximum rate of growth occurs during adolescence
what is the strongest indicator of risk of osteoporosis?
Bone acquisition during childhood and adolescence
How does bone develop in foetuses?
Cartilaginous tissue precedes bone formation
Primary ossification centres form ~8 weeks after fertilisation
What are the areas of a bone to start developing?
Primary ossification centres
Stages of bone development?
- Cartilage cell increase in cell number and size
- Tissue is calcified
- Tissue is invaded by nutrients and osteoblasts
- Osteoclasts remodel the internal structure
What is the outer layer of bone called?
Harder external cortex
What is the less dense internal region of bone?
Hollow structure
In regards to weight and strength, what is a bone?
Light and strong
How do bones develop?
Via endochondral ossification
When are secondary ossification centres present?
After birth until growth stops
Where can all stages of bone development be seen?
In a growth (epiphyseal) plate
Stages of development in an epiphyseal plate?
Resting cartilage Cartilage proliferation Cartilage maturation Cartilage calcification Ossification
What is a sign ossification has occured?
Osteoblasts forming bone
What is a sign cartilage calcification has occurred?
Extracellular matrix becomes calcified
What is a sign of cartilage maturation?
Hypertrophy
What is asign of cartilage proliferation?
Hyperplasia
Where are curved bones thickest?
Where they are most likely to buckle
Where are long bones thickest?
Midway down the shat
Where are bony projections found?
Where heavy, active muscles attach
Where do lines of stress form in the bone?
On the trabeculae
What happens to trabecular during decay?
A decrease in the number of traberculae (“small rods”)
How is a muscle fibre formed?
A fibre is made from a large number of fused embroyonic cells (myoblasts)
Why does a muscle have multiple nuclei?
For it is formed from multiple embryonic cells (myoblasts)
What are satellite cells?
Stem cells that can differentiate into myoblasts and sit within the endomysium
When do myoblasts fuse to other muscle cells?
During growth and repair throughout the life-span
What are satellite cells most important for during maturation?
Hypertrophy
What do myoblasts cells do in utero?
Elongate and aggregate into bundles. They fuse longitudinally and form the multinucleated fibres (myotubes)
When do myoblasts become striated in utero?
Striated by the 3rd month of development
How are myotubes formed?
By fusion of myoblasts
When do our muscles start producing force?
12 weeks1
Total weight of infant that is muscle?
~25%
Total weight of adult Male (20 yrs) that is muscle? What about female?
~40%, female roughly 30-35%
Contraction speed of slow oxidative muscle fibre?
Slow
Contraction speed of fast oxidative muscle fibre?
Fast
Contraction speed of fast glycolytic muscle fibre?
Fast
Major ATP source of slow oxidative muscle fibre?
Aerobic respiration
Major ATP source of fast oxidative muscle fibre?
Aerobic respiration
Major ATP source of fast glycolytic muscle fibre?
Glycolysis
Rate of fatigue of slow oxidative muscle fibre?
Slow
Rate of fatigue of fast oxidative muscle fibre?
Interediate
Rate of fatigue of fast glycolytic muscle fibre?
Fast
Mitochondria count of slow oxidative fibres?
Many
Mitochondria count of fast oxidative fibres?
Many
Mitochondria count of fast glycolytic fibres?
Few
Myoglobin content of slow oxidative fibres?
High (red muscle)
Myoglobin content of fast oxidative fibres?
High (red muscle)
Myoglobin content of fast glycolytic fibres?
Low (white muscle)
Can an ultrasound give information about fibre types?
No
Two types of input to motorneuron in the spinal cord?
Excitatory and inhibitory inputs
Where do excitatory and inhibitory inputs generate?
Excitatory and inhibitory post synaptic potentials (EPSP and IPSP’s)
Motor areas of the brain?
Brain stem and cerebellum
What does the brain stem for for motor control?
Basic movement and posture
What does the cerebellum for for motor control?
Refining information
What does the spinal cord do in regards to motor control?
Reflex activity (involuntary movement)
Steps of using ATP during skeletal muscle contraction?
- Contraction begins when ATP is hydrolosyed to create ADP and an inorganic phosphate
- This energy allows the myosin head to extend and attach to a binding site on the actin forming a cross bridge
- Allowing the power stroke. Pulling of actin across myosin. Shortening the sacromere
- ADP and inorganic phosphate are released during power stroke
- Myosin remains attached to actin (in a lo energy state until a new ATP molecule binds
What are the three types of connective tissue?
Collagenous fibres
Reticular fibres
Elastic fibres
What do collagenous fibres do?
Provide strength and flexibility
What do reticular fibres do?
Join connective tissue to adjacent tissues
What do elastic fibres do?
Make tissue elastic
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.
What is the most widesead connective tissue in the vertebrate body?
Loose connective tissue
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
Where does loose connective tissue get its name from?
The loose weave of its fibres
What is fibrous connective tissue? Where is it found?
Tissue dense with collagenous fibres. Found in tendons and ligaments.
What connects bone to bone?
Ligaments
What connects muscles to bone?
Tendons
What repeating units form the concrete structure of bone?
Osteons
What is the energy storage cell?
Adipose
What does cartilage consist of?
Collagenous fibres embedded in a rubbery protein-carbohydrate complex
In cartilage, what is the rubbery protein-carbohydrate complex called?
The chondroitin sulphate
What cells are found in a chondroitin sulphate?
Chondrocytes
What do chondrocytes do?
Secrete the collagen and chondroitin sulphate, which together make a strong yet flexible supportive material.
What cell shape are smooth muscle?
Striated and spindle shaped
What muscle types are voluntary and involuntary?
Muscle = V
Smooth Muscle = IV
Cardiac Muscle = IV
How does cardiac muscles connect? What does this achieve?
Via intercalated disks, which relay signals from cell to cell and help synchronise heart contractions
What do glial cells do?
Help nourish, insulate and replenish neurons. In some cases modulate neuron functioning.
What junctions are found between nerves?
Gap junctions
What do neurotrasmitters package into at the presynaptic neuron?
Synaptic vessicles
What is the distance of the synaptic cleft typically?
50nm
What is a ligan-gated ion channel also called?
Ionotrpic receptor
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
What occurs when two ESPS signals happen in rapid summation?
Temporal summation
What occurs when two different sources of postsynaptic neurons occur simultaneously?
Spatial summation
In G-protein responses, what does the neurotrasmitter bind to?
A metabotropic receptor
What enzyme terminates acetylcholine?
Acetylcholinesterase
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.
Two major classes of aetylcholine receptors?
One is a ligand-gated ion channel, other is ionotropic found in the CNS and PNS
Most common neurotrasmitter in the CNS of vertebrates?
Glutamate
Difference between vertebrates and invertebrates at the neuromuscular junction?
Invertebrates use glatamate instead of acetylcholine
What is the neurotransmitter at most inhibitory synapses in the brain?
Gama-aminobutyric acid (GABA)
What does binding of GABA to receptors in postsynaptic cells result in?
Permeability to Cl-, resulting in an IPSP
What does vallium bind to?
A GABA receptor in the brain (causing IPSP)
What does nicotine bind to?
A ionotropic receptor that acetylcholine binds to, resulting in physiological and psychological stimulaton
Five types of neurotransmitters?
Acetylecoline Amino acids Biogenic Amines Neuropeptides Gases
Most diverse group of neurotransmitters?
Neuropeptides
What type of neurotransmitter is nonadreneline?
A biogenic amine
What do depression drugs usually focus on? (What type of neurotransmitter?)
Increasing brain concentrations of biogenic amines
How does prozac work?
It enhances the effect of serotonin by inhibiting its reuptake after release
How does botox work?
By blocking transmission at synapses (inhibiting acetylcholine) of particular face muscles
What are neuropeptides?
Relatively short chains of amino acids that serve as neurotransmitters and operate via metabotropic receptors
Key neurotransmitter of pain? What type os neurotransmitter is it?
Substance P - a neuropeptide
What decrease pain reception?
Endorphins
In addition to decreasing pain, what do endorphins do?>
Reduce urine output, decrease respiration, produce euphoria and stimualte good emotions
How do opiates work?
By binding to same receptors as endorphins
How do males become erect?
By release of nitric oxide into tissue of penis
How does viagra work?
By inhibiting an enzyme that terminates the action of nitric oxide
How is nitric acid stored? (As a neurotransmitter)
It’s not stored, but synthesised on demand
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.
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
Three membrane activites that occur both in fertilisation of an eff and in neutrotransmission across a synapse?
Membrane depolarisation
Exocytosis
Membrane fusion
Major component of thin filaments? What type of protein is it?
Globular protein actin
What type of molecules make up thick filaments?
Myosin molecules
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
What does calcium bind to in the sacromere?
Troponin
What does tropomyosin do to myosin?
Blocks the myosin head
How does calcium move tropomoyosin out of the way?
By binding to troponin and it then moves tropomyosin out of the way
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
Difference between afferent and efferent?
Afferent takes information to the cns
Efferent is the effector (to the muscles)
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
Percentage of body weight that is bone?
15%
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