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
