Musco Flashcards
Describe how individual bones are classified.
Long
short
flat
irregular
what is the long bone comprised of
epiphysis - end of bone
diaphysis - shaft
metaphysis - growth plate fuses
describe the biomechanical aspects (what pressure can be placed ) of a long bone
compresion tension shear torsion compression and tension (bend)
describe the gross anatomical features of skeletal muscle.
- Belly: also called the head. Enveloped in a connective tissue sheath.
- Tendon: dense regular fibrous connective tissue
- Origin: proximal attachment
- Insertion: Distal attachment
classify skeletal muscle based on the orientation of its fibres
Pennate (feathering):
Unipennate: (e.g flexor digitorum profundus) Bipennate: (e.g infraspinatus)
Multipennate: (e.g subscapularis)
Strap: (e.g omotransversarius)
- Fusiform: (e.g biceps brachii)
- Circular: (e.g orbicularis oris)
- Sphincter: (e.g anus)
what is Concentric contraction:
Muscle shortens, bones become closer together
what is Eccentric contraction
Muscle elongates under tension
what is Isometric contraction
Both sides contracting with no change in length
Agonist or prime mover muscle what does it do
Making movement
what is Antagonist muscle
muscle that allows action to happen
Synergists muscle does what ?
Muscles that work together (e.g bicep and triceps)
Fibrous connective tissue
- name the types of fibres and the primary cell
(proper)- fibroblasts are the primary cell type
- dense regular
- dense irregular
- loose superficial
- specialised connective tissue
What is made from dense regular tissue
tendons, ligaments and aponeuroses (tendon sheets)
What is made from dense irregular tissue
deep fascia, joint capsules, tendon sheaths, dermis
what is made from loose superficial tissue
superficial fascia, around blood vessels, within organs to provide structure
what is specialised connective tissue
- Bone
- Cartilage
- Adipose
what is the mechanical role of connective tissue
resist stresses/ forces upon body (compression, tension, torsion, shear, bending)
what is the structural role of connective tissue
Originate from the mesenchymal cells of the embryo which are derived from mesoderm
• Composed of cells, ECM, and ground substance
what is ground substance and whats its purpose
- Binds ECM components and cells together
- Medium for nutrient and waste diffusion
- Composed of glycosaminoglycans (GAGs), proteoglycans, glycoproteins, water.
what is elastin and whats its purpose
- Protein with elastic properties which allow stretch and recoil to original position -Elastic fibres have cross links
- Found in arteries, lungs, elastic cartilage, some ligaments/ tendons, dermis of skin
what is collagen and whats its purpose
- Arranged in fibres composed of smaller subunits called fibrils
- Fibrils are composed of collagen molecules which are a triple helix of alpha chains
what does tendons and ligaments contain that give it the ability to resist tension
collagen
what is the primary cell type of cartilage
Chondrocyte
what are the types of cartilage and their purpose
hyaline
- joint surfaces to reduce friction
- fetal bones and trachea
articular
- within joints
- avascular allowing it to pass nutrients and blood through synovial fluid
fibrocartilage
- intervertebral discs
elastic
- ears
Describe synovial membrane structure and function
- Clear viscous fluid – honey like if colour and consistency
- Modified transudate from plasma
- Rich in proteoglycans and hyaluronic acid
- Function is lubrication, shock absorption and nourishment of the chondrocytes of articular cartilage
what is the synovium
- Joint capsule is outer layer (connective tissue)
- High blood supply- plasma is filtered and the modified transudate is passed into the joint cavity.
- 2 types of synoviocytes: one produces the transudate and looks like a fibroblast and the other is like a tissue macrophage
Describe the structure and functions of yellow adipose tissue
Functions: Insulation, energy source during starvation, padding of vital structures (i.e shock absorption)
- Found under skin, in diaphysis of adult bones, amongst connective tissue, in digital and metacarpal/ tarsal pads
- adipocyte is the primary cell type -appear which histologically
Describe the structure and functions of brown adipose tissue
Functions: heat production in hibernation and newborns -Abundant mitochondria and small lipid droplets within cells
what are the functions of bone
- Mechanical
- Protection of vital organs
- Calcium reservoir
- Bone marrow for production of blood cells
what are the three types of cells are found in bones and what do they do
- Osteoblasts: Bone producing cells
- Osteocytes: Mature osteoblasts which maintain bone matrix
- Osteoclasts: Bone degrading cells
describe compact bone
found in diaphysis high strength bone is arranged in lamelle centre of lamelle = osteon centre of lamella contains haversarian canal
describe spongey bone
found in epiphysis
decreases weight of bone
red bone marrow in trabeculae
provides resistance to compression
what are the two lining layers of compact bone
periosteum - outer surface
endosteum - inner surface
what is the process of Intramembranous ossification
- Occurs in flat bones
- Connective tissue precursor becomes mineralised
- Mineralised bone matrix is deposited into connective tissue model
- Osteoblasts in the periosteum produce matrix- first osteoid, then hydroxyapatite -Organised into thin compact bone cortex surrounding spongy bone
- Growth is appositional to increase size during maturation of animal
describe the process of Endochondral ossification
- Cartilage precursors of bones
- Long bones, short bones, vertebrae, ribs
- Hyaline cartilage bone model is gradually replaced by mineralised bone matrix -Cartilage model starts to become mineralised at the primary ossification centre (centre of the bone), secondary ossification centres then develop in the epiphyses
- Long bones have a physis at each end between the epiphysis and metaphysis. This physeal cartilage allows long bones to increase in length in growing animals
what direction does Endochondral ossification cause bone to grow in
length ways
what direction does inter membranous ossification cause bone to grown in
increases in width
how is bone remodelled
Spongy bone has greatest capacity for remodelling
Wolff’s Law: Bone responds to the stresses placed upon it due to changes in function/ use
how does bone heal
Periosteal osteoblasts deposit new bone over fractured site
-For bone healing to occur there must be gap bridging, dequate blood supply, no movement, no infection, weight bearing.
what is a synarthrosis joint and how can it move
immoveable joint
fibrous joint
what is a amphiarthrosis joint and how can it move
slight moveable joint
cartilaginous joint
what is a diarthrosis joint and how can it move
unrestricted movement
synovial, articular
what are the two tissue types in the CNS
Grey matter= Areas of nerve cell bodies (nuclei of neurons) White matter= Regions of neuron axons only
what are the brains components and functions
input and output to the body
-Voluntary movement
-Sensory stimuli: vision, hearing
-Involuntary functions: heart rate, gut functions
Brain neurons connect to the spinal cord to send messages to the body via nerves.
• Cerebrum: Interpretation of vision and sound, decision making, initiation of movement, memory.
• Cerebellum: co-ordination of movement
• Brainstem: Monitoring of visceral functions
what is the function of the spinal cord
-Neurons and their axons are found in the
spinal cord -Transfer messages to and from the brain
what is the role of the PNS
-Peripheral nerves connect the spinal cord to the body -Nerves carry information to and from the body
what is the function of a neuron
-Changes in intracellular K and Na ion concentrations along axon causes depolarisation called action potentials
what is an action potential
-Neurotransmitter chemical release at synapse to next neuron
describe and afferent nerve
Afferent (incoming) neurons
-sensory nerves carry messages back to the spinal cord and then to brain -pain, temperature, position, pressure
describe an efferent nerve
Efferent (outgoing) neurons
Somatic efferent ‘motor neurons’: to skeletal muscle
Autonomic efferent neurons: to cardiorespiratory, gastrointestinal, urogenital
what are the two divisions of the autonomic nervous system
Sympathetic nervous system
Parasympathetic nervous system
what is the response of the Parasympathetic nervous system
Rest and digest response
-Increases gut smooth muscle and glandular function, increases blood flow to gut, lowers heart rate and blood pressure
what is the response of the Sympathetic nervous system
Fight or flight response
-Increase heart rate, dilate airways, increases blood pressure, increases blood flow to muscles, adrenaline release
describe the classification and function of skeletal muscle
striated
voluntary
function = movement and heat production
describe the classification and function of cardiac muscle
striates
involuntary
function = pump blood
describe the classification and function of smooth muscle
non striated
involuntary
function = movement and organ size
explain the structure of skeletal muscle
- long bundles of cylindrical muscle fibres
- groups of fibres are bindle together to form fascicle
- connective tissue surround the outside of the the bundles
name the 3 connective tissue layer in skeletal muscle fibre and what they hold together
individual fibres (endomysium), fascicles (Perimysium) whole muscles (Epimysium).
what are myofibrils
each muscle fibre is divided into myofibril
myofilaments, consisting of contractile proteins.
-Myofilaments are arranges into repeating units (Sarcomeres)
myofibrils are composed of ….
thick (myosin) and thin (actin) filaments
what is the role of the sarcomere
functional unit of the contractile process
what is the interaction of actin and myosin
interaction between the myosin globular heads is regulated by proteins tropomyosin and troponin
why is titin useful
Elastic and helps sarcomeres spring back when stretched Nebulin: inelastic, stabilises actin
explain the sliding filament theory
- When a muscle fibre contracts the thick and thin filaments do not shorten but slide over one another.
- Cross bridges are formed by the thick filaments attaching to the thin filaments and pulling them towards the centre of the sarcomere
what is the 2 role of ATP in the cross bridge cycle
- Energy source: ATP hydrolysis provides the energy for cross-bridge movement- enables myosin head to become cocked.
- Allosteric regulator: Binding of ATP to myosin breaks the link between actin and myosin. This allows the cycle to be repeated
what is the role of calcium in the cross bridge cycle
-When calcium binds to troponin its conformation is altered causing tropomyosin to change position and expose the binding site for myosin
-Calcium is a key factor in control of contraction
ca is released from the tubules over the sarcoplasmic reticulum
name the two regulatory proteins in the cross bridge cycle
troponin & tropomyosin
what is the role of troponin & tropomyosin in the cross bridge cycle
In resting muscle, binding sites for myosin are masked by tropomyosin.
calcium binds to troponin its conformation is altered causing tropomyosin to change position and expose the binding site for myosin
what is excitation coupling
- Excitation coupling describes the relationship between depolarisation and contraction. -Action potentials triggers muscle contractions
- Excitation at the motor end plate initiates propagation of an action potential down the sarcomere and T-tubular system, triggering the release of calcium into the sarcoplasm from the terminal cisternae of the sarcoplasmic reticulum.
define motor unit
Motor neuron + muscle fibre it innervates
how many muscle fibres are innervated by a motor neurone
Each skeletal muscle fibre is innervated by a motor neuron
how is an action potential generated in skeletal muscle
- Binding of acetylcholine results in opening of sodium channelsàdepolarisation of motor end plate
- Depolarisation of motor endplate results in depolarisation of adjacent regions of the membrane through activation of voltage gated sodium channels which allows rapid influx of sodium.
- Sodium channels are rapidly inactivated and the cell repolarises towards the resting membrane potential.
- repolarisation is prompted by opening of additional potassium channels.
- Arrival of AP in skeletal muscle causes release of calcium from SR which intitates contraction
what occurs when the action potential arrives at the motor end plate
- Arrival of Ap causes acetylcholine to be released from vesicles
- Ach binds to nicotinic receptors in the endplate and causes opening of ion channels in the posy synaptic membrane
- Ap is transmitted down T tubules and causes calcium release from SR
what occurs during ,muscle contraction
- When AP is terminates, release of calcium ceases. -Calcium is pumped back into SR
- ATP is required to pump calcium back into SR
how many cervical bones are in the vertebral column
Cervical: 7 common to all mammals
how many Thoracic bones are in the vertebral column of the horse and dog
Thoracic: 13 in dog, 18 in horse
how many lumbar bones are in the vertebral column of the horse and dog
Lumbar: 7 in dog, 6 in horses
how many sacral bones are in the vertebral column of the horse and dog
Sacral: 3 fused vertebrae in dogs, 5 in horse
how many caudal bones are in the vertebral column of the horse and dog
Caudal: about 20 in dogs and horse
what does the intervebral disc have that allows it to act in the way to does
- Fibrocartilaginous
- Acts as shock absorbers
- Cartilaginous joint
- Annulus fibrosus (tough outer fibrous connective tissue)
Describe the atlantoaxial joint.
Pivot joint (rotates) Synovial
what do short ligaments do
connect adjacent vertebrae
what do long ligaments do
pass over several vertebrae
what is isometric contraction and explain sarcomeres response
same length contraction
Sarcomeres shorten slightly and elastic components stretch
what is isotonic concentric contraction and explain sarcomeres response
sotonic concentric contraction:
-Muscle shortens while the load remains constant
Sarcomeres shorten significantly and elastic elements stretch
what is isotonic eccentric contraction and explain the sarcomere response
Isotonic eccentric contraction:
- Load exceeds muscle tension
- Load pulls muscle to a longer length
- Sarcomeres are lengthening while generating force
what is a muscle twitch
mechanical response of a muscle to a single action potential.
what are the three phases of a muscle twitch
latent period,
contraction phase,
relaxation phase.
what does the frequency of an action potential do to a muscles fibre
determines the force developed by a muscle fibre
what does low frequency stimulation do to a muscle fibre
allows muscle fibres to relax completely before the next contraction.
what is summation
further stimulus is applied before the muscle has completely relaxed, causing the muscle to unfused tenanus
what does high frequency stimulation of a muscle fibre result in
tetanus
what does sarcomere length (muscle length) do to force of contraction
Maximum tension is achieved when muscle is set at lengths near its normal relaxed length
what are the two way force of contraction is regulated
- Increasing frequency of stimulation (only increases 3-5x)
2. Increasing the number of motor units activated (recruitment)
what is motor unit recruitment how does it impact on muscle contraction
Increasing recruitment of further motor units will increase the velocity of the movement
how does work relate to distance
Work= Force (N) x Distance (m)
what is work
the amount of work a muscle can do depends on its volume
what does muscle force depend on
- Muscle force depends on cross-sectional area
- Length of muscle does not contribute to force but is important in determining the amount of work done.
what pathway create ATP of muscle contraction
mitochondrion
- Fatty acid synthesis
- pryruvate from glucose
cytosol
- glucose from glycogen store
how does anaerobic catabolism supply muscles with energy
Anaerobic phosphorylation of ADP using high energy phosphate stores in muscle
what is is used to make energy in anaerobic glycolysis
-Pyruvate converted to lactate
explain the benefits of anaerobic glycolysis
- Anaerobic energy production is fast but inefficient -Useful when energy is needed quickly
- Leads to significant depletion of muscle glycogen stores
how does aerobic energy supply the body with ATP
. Aerobic (oxidative) phosphorylation of ADP using CHO stores
- Glycolysis
- TCA cycle
- Electron Transport Chain
how much ATP is yielded from aerobic metabolism
Complete aerobic metabolism of glycogen yields 37-39 molecules of ATP Complete aerobic metabolism of glucose yields 36-38 ATP
explain the beta oxidation of fatty acids
- Fat is energy dense and yields more ATP than the same mass of CHO -Requires more oxygen
- Slower energy release
what is the benefit of protein for energy metabolism
- Provides energy is cases of extreme exhaustion, starvation or disease.
- Amino acids are deaminated, enter the urea cycle and eventually metabolised to enter the TCA cycle at various points
what is energy partitioning
Energy supply during exercise is not derived from one source. There is an integration of aerobic and anaerobic pathways
what do type 1 muscle fibre do
slow contraction
- endurance
what do type 2a muscle fibre do
fast contracting
- endurance and stamina
what do type 2b muscle fibre do
fast contracting
- sprinting and strength
explain muscle fibre recruitment
- ensure smooth locomotion
- dependant on gait, speed, workload, duration
as speed nd power increase more type 2 fibres are recruited
how are cardiac muscle fibres arranged
Striated due to the way myofibrils are organised into sarcomeres
what is the benefit of increased mitochondria in cardiac muscle fibres
Rich in mitochondria (aerobic metabolism provide ATP)
what are the two types of cellist skeletal muscle fibres
Contractile (action potential is needed)
• Autorhythmic (pacemaker) = spontaneously depolarise cause and AP which
simulates a heart beat and sets the rate
why are AP so long in cardiac muscle fibres
leaky sodium channels
• Ap and contraction are similar in length
• This ensures coordinated relaxation and refilling between beats
• Summation (joining of stimulus to produce a stronger contraction) cannot occur in
cardiac muscle
what is the difference in smooth muscle arrangement
Actin and myosin (diagonal bundles) but not organised into sarcomeres
• No striations
what are the two types of smooth muscle and what do they do
Visceral
- connected via gap junction
- hormonal control (stretch sensitive)
- GI tract
multi unit
- synaptic connections (not gap junctions)
- contract independently
- autonomic nerve control
- hormone control (not stretch sensitive)
how are contractions initiated in smooth muscle
- cross bridge cycle
- lower frequency of of the cycle but longer lasting
- irregular arrangement of myofibrils = max force
what is excitation coupling
-No troponin thus binding sites for myosin are not masked
Activations come from Ca2+ to a calcium modulated protein (calmodulin) = regulation
• This is activated and binds to enzyme myosin light chain kinase thus activating it
• This the hydrolyses ATP and phosphorylates proteins
