Muscles Flashcards
What are the 3 types of muscles and functions?
Cardiac=Heart, Doesn’t fatigue easily and is involuntary
Smooth(striated)=Walls of hollow organs, Stretches/maintains prolonged tension and is involuntary
(40%) Skeletal (striated)=Attached to skeleton by tendons (bundles of collagen), Voluntary control and requires nerve stimulation
How do muscles normally work together?
They usually work in antagonistic pairs
Flexor contracts = limb bends e.g. bicep contracts, tricep relaxes so decreases joint’s interior angle
Extensor contracts =limb straightens e.g. tricep contracts, bicep relaxes so increases joint’s interior angle
What are;
Flexor and Extensor
Abductor and Adductor
Levator and Depressor
Supinator and Pronator
Rotator (or circumduction)
Sphincter
Flexor/Extensor=makes angle of two parts more acute versus more obtuse
Abductor/Adductor= e.g In the hip your abductor moves legs away (sideways) from the midline and your adductor moves legs back and towards the midline.
Levator/Depressor: Levator=supporting and raising the pelvic visceral structures.
The depressor anguli oris muscle (triangularis muscle) is a facial muscle. It is associated with frowning, moves a structure above and below a horizontal midline.
Supinator v Pronator: pronation refers to an inward rolling of the foot, supination is an outward rolling that causes the foot to rise above the ground as you walk.
Rotator (or circumduction): rotates a ball and socket joint on its axis
Sphincter: A ring-shaped muscle that relaxes or tightens to open or close a passage or opening in the body. Examples are the anal sphincter
What is the structure of muscles?
Myoblast cells –>myotubes –>Fibres (1 foot long, 10-100 micron diameter) –>Fibres arranged into myofibrils
*Myofibrils contain two types of filament
-Thin are made of the protein: actin
-Thick are made of the protein: myosin
Overlapping filaments = “Sarcomere”= The functional unit of muscle fibre
Describe myosin and actin
*Myosin=heads and tails (H zone is the tails)
*Each head has an actin-binding site
*Each head has an ATP-binding site
Actin= covered by tropomyosin which prevents myosin from binding
Explain sliding filament theory
Calcium binds to troponin which causes a conformational (shape) change and moves tropomyosin out of the way so the myosin head can bind.
ATP binds to myosin and then there’s a conformational change.
myosin then unbinds
ATP hydrolysed to ADP = energy released so cocks myosin head which then binds to a new actin myosin binding site this process causes a powerstroke
What is the force produced by a muscle determined by?
*The number of cross bridges in a particular cross section (i.e. in parallel). More fibres in parallel as a larger cross-section area means more force.
*A higher Actin/Myosin (A/M) ratio
*A pennate arrangement of fibres
What is the speed of muscle contraction determined ?
*The number of cross bridges rowing simultaneously in series
*Having shorter sarcomeres
*Having longer fibres
Explain in more depth the 3 types of muscles
*slow oxidative fibres= Red, “Slow twitch”(aerobic)
*Fast oxidative fibres “fast twitch” (aerobic)
*Fast glycolytic fibres=White, “Fast twitch” (anaerobic)
Explain the differences between sustained ATP muscle use and powerful quick muscle use using;
Contraction speed =Slow twitch, Fast twitch
ATP synthesis pathway = Oxidative, Glycolytic
Colour (from myoglobin) =Red White
Myoglobin content
Mitochondrial content
Glycolysis enzymes
Sarcomere length
A/M ratio
Fibre diameter
Sarcoplasmic reticulum
*Sustained Efficient ATP use;
Myoglobin content=high
Mitochondrial content= high
Glycolysis enzymes= low
Sarcomere length= long
A/M ratio= high
Fibre diameter= low
Sarcoplasmic reticulum= poorly developed
*Powerful Fatigues quickly;
Myoglobin content= low
Mitochondrial content= low
Glycolysis enzymes= high
Sarcomere length= short
A/M ratio= low
Fibre diameter= high
Sarcoplasmic reticulum= well developed
Explain what white and red muscles do and what animals may have which?
White
Plaice, Pike, Chicken, Rabbit, Large Cats
*Ambush predators & their prey= Fast, but fatigue quickly
Red
Mackerel, Trout, Mallard, Kestrel, Hare, Dog, Wolf
*Endurance predators, migrants= Slow and sustained force
Bioenergetics of locomotion
what are the three forces acting on animals?
*Inertia (tendency to stay in one –static or mobile – state)
*Friction (drag, counteracted with thrust)
*Gravity (counteracted with lift and buoyancy)
surface area and mass would affect each of these
What is Passive locomotion?
Adaptations to use environment for locomotion
Don’t control their direction
Benefit= no energy input
Cost= no control
Explain how certain fish reduce energy loss in locomotion of fluids
Movement in water
*Neutral buoyancy (Static lift cancels out gravity = inertia in the vertical plane) e.g Sharks have a liver filled with low density squalene oil.
Primitive fish (e.g. eels): Physostomatous swim bladder
which is connected to gut, regulate by surface gulping or secretion.
Teleost fish: Physoclistus swim bladder (air controls buoyancy)
Gut connection lost; regulate by secretion
*benefit: minimal energetic cost
cost: risks of fast vertical movement
Explain the physoclistus swim bladder
Skeletal muscle that contracts/expands with ambient pressure Smooth muscle so few capillaries & lined with impermeable guanine crystals.
Counter-current exchange; hairpin loop increases blood gas concentration entering the gland
Longer loop in deep than shallow water fish
Explain other forms in which fish may reduce energy costs in locomotion of fluids?
Movement in water
Fusiform shape
-Laminar flow reduces drag
-Energy saved from thrust.
What is Reynold’s number?
Reynold’s number = speed of propulsion x length/viscosity
Low = flow dominated by laminar flow
High = turbulence from variation in fluid speed and direction
How do small medium and large animals prevent energy waste due to unsteady flow of water
S.A ~ drag, Mass ~ velocity
small and large organisms maximise thrust and use a steady pace to minimise energy waste
Medium size organisms= have unsteady flow propulsion mechanisms that use these flows, e.g. shrimp jet propulsion
Locomotion in the air
How to save energy?
*Minimise weight
*Pneumatized bones (Counteracts gravity)
*Low wing aspect ratio: ratio of (span) to area
*Low wing loading: ratio of weight to span
Increases lift and reduces energy costs
What is isotonic contraction and isometric contraction?
*Isotonic contraction= involves shortening of the muscle to cause movement about a joint (i.e. extensive actin/myosin sliding)
*Isometric contraction= involves resisting an external load without shortening of the muscle (i.e. virtually no actin/myosin sliding)so increases tension in tendons
therefore isometric is more efficient than isotonic
Explain the difference in muscles between flapping and gliding birds?
Flapping flight in birds have wing muscle fibres with short sarcomeres, fast-twitch (white) muscle and contract isotonically but they consumes 7 x Basal Metabolic Rate
Gliding flight in birds: wing muscle fibres have long sarcomeres, slow-twitch (red) muscle and contract isometrically and consumes 2 x BMR.
Why don’t all birds glide then?
Harder to maneuverability, less speed and more difficult to land.
Locomotion on land
*Some (less) friction, no need for buoyancy but each step must overcome inertia.
*store elastic potential energy to help overcome inertia.
