week 9 - muscel and movement

Describe bipedal and quadrupedal?

• Bipedal - 2 feet, usually upright body posture

• Quadrupedal - 4 feet, usually horizontal posture

• Some can be both such as quokkas and wallabies - but describe using predominant movement

Describe superior and inferior?

• Superior - towards head, upper part of body, above another

• Inferior - towards feet, lower part of the body, below another

Describe anterior, posterior, dorsal and ventral in humans?

• Anterior - towards front of body

• Posterior - towards back of body

• Dorsal - towards back or upper surface of body

• Ventral - towards belly of lower surface

Describe anterior, posterior, dorsal and ventral in animals?

• Anterior - towards the head

• Posterior - towards the tail

• Dorsal - towards the back or upper surface of body

• Drowsed the belly or lower surface

Describe superficial and deep?

• Superficial - closer to the body

• Deep - farther from the body surface

Describe proximal and distal?

• Proximal - closer to the point if attachment

• Distal - farther from the point of attachment

Describe medial and lateral?

• Medial - closer to the midline of the body

• Farther from the midline of the body

What are the 3 skeleton types?

• Hydrostatic skeleton

• Exoskeleton

• Endoskeleton

Describe the defining features, advantages, disadvantages and examples of hydrostatic skeleton?

• Flexible closed compartments contain fluid

• Contraction of muscles change shape, producing movement

• Advantages, flexible skeleton, energy efficient

• Disadvantages, least protection, requires moist environment, limits body size

• Examples - flatworms

Describe the defining features, advantages, disadvantages and examples of exoskeleton?

• Found outside the body

• Made of calcium carbonate

• Advantages - protection from predators, prevents water loss

• Disadvantages - limits growth, Skelton must shed, demand for minerals

• Examples - arthropods

Describe the defining features, advantages, disadvantages and examples of endoskeleton?

• Hard skeleton contained inside soft tissue

• Made of bone

• Advantages - support large body size, no shedding, support range of movement

• Disadvantages - sift tissue exposed, demand for minerals

• Examples, vertebrates

Describe implications of skeleton growth type?

• hydrostatic skeletons or endoskeletons grow continuously as skeletal elements are internal

• Exoskeleton grow through process of moulting

• External skeleton is shed, and replaced by larger one - as rigid exoskeleton cannot grow continuously

What are the useful materials in building organism?

• Calcium carbonate

• Calcium phosphate

• Cartilage

• Chitlin

• Collagen

• Keratin

Describe calcium carbonate?

• Forms exoskeletons for marine invertebrates

Describe calcium phosphate?

• gives vertebrates bones and teeth - hardness, compressive strength

Describe cartilage?

• Flexible connective tissue that supports joints

Describe chitlin?

• Main component of arthropod exoskeleton

Describe collagen?

• Fibrous protein that provides flexibility, tensile strength and resistance to stretching in connective tissue

Describe keratin?

• Structural protein that forms hairs, nails, claws

Describe bone structure and bone density in flying birds?

• Required for little body mass when flying

• Bones are pneumatic, filled with air, bone density is reduced while maintaining strength

Describe bone structures and density of diving birds?

• Required to dive and overcome buoyancy

• Less pneumatic and more dense

• Increased bone density mean less buoyancy

Describe bone density for aquatic mammals?

• Grazing mammal - needs to remain submerged - increased bone density

• Fast swimming mammal - needs to swim fast in the water - reduced bone density - less mass helps swim faster

Describe organisations of muscles from largest to smallest?

• Muscle fibres

• Myofibril

• Sarcomere - Thin (actin) and thick (myosin) filaments

Describe how muscle contraction works?

• At rest, actin and myosin partially overlap

• During contraction, myosin forms cross bridge, and pulls actin filaments towards M line

Describe structure of thick filament?

• Head and tail

• Head has actin binding site and ATP binding site

Describe structure of thin filament?

• Troponin

• Actin

• Tropomyosin

Describe on a molecular level how muscles contract?

• Myosin head bound to ATP in low energy configuration

• ATP hydrolyses to ADP and phosphate - cocks myosin head to high energy configuration preparing for power stroke

• Powered myosin attaches to binding site, this forms bridge between thick and thin

• ADP and phosphate released, myosin head snaps back to low configuration state pulling action, this is power stroke

• Cycle resets

Describe excitation contraction coupling?

• Process of electric signals triggering the release of calcium ions, producing muscle contraction

Describe the process of excitation contraction coupling?

• Action potential arrives at synaptic terminal of neuromuscular junction. Ach released from terminal to cleft

• Ach binds to receptors, opening ion channels which allow sodium in, depolarises cell

• Depolarisation causes action potentials which travel down infoldings (T tubules)

• Calcium ions are released into sarcoplasmic reticulum

• Cross bridge formation creates power stroke

• Calcium ions recycled back into sarcoplasmic reticulum

Describe how muscles generate contractions of different strengths?

• Muscles recruit motor units

• Small motor unit - less muscle fibres - small movement

• Large motor unit - more muscle fibres - powerful movement

Describe hennemns size principle?

• Motor units recruited from smallest to largest

• When greater force is needed, more motor units recruited simultaneously

Describe tetanus?

• When action potentials arrive at high frequencies to sustain a contraction

Describe locomotive of hydrostatic skeleton with simple muscles?

• Implications - pressurised body fluid acts as skeleton, no joints or tendons

• Consequence- movement limited from side to side

Describe locomotive of hydrostatic skeleton with complex muscles?

• Implications - Pressurised fluid works both circular and longitudinal muscle, still not tendons or joints

• Consequences - More versatile movement

Describe locomotive of exoskeleton?

• Implications - external skeleton allows for articulated joints

• Consequences - allows for rapid and powerful movements, walking, jumping, flying

Describe locomotive of endoskeleton?

• Implication - Internal skeleton allows for moveable joints and tendons

• Consequence - wide range for powerful movements

Describe fibrous joints?

• Bones connected directly by dense fibrous tissue

• Little to no movement

• Skull sutures

Describe cartilaginous joints?

• Bones connected by cartilage with no joint cavity

• Slight movement, more than fibrous joints

• Growth plates

Describe synovial joints?

• Bones separated by fluid filled joint cavity

• Greatest range of motion

• Knee, hip, shoulder

Describe slow twitch muscle fibres?

• Contract slowly but resist fatigue

• Rely on aerobic respiration

• Suited for endurance locomotive

Describe fast twitch muscle fibres?

• Contract quickly but fatigue fast

• Rely on anaerobic respiration

• Suited for burst performance

Describe the process of knee jerk reflex?

• Tap of patellar tendon below knee stretches quadriceps muscle

• Muscle spindles inside quadriceps send action potentials along sensory neuron to spinal cord

• Sensory neuron stimulates motor neuron to quadriceps through Interneuron, inhibiting the hamstring

• Hamstring muscles relax while quadriceps contract