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[h] IB DP Biology HL B3.3 Muscle and motility Flashcards
[q] identify the correct definition of the term ‘sessile’
[a] animals that are permanently fixed to a particular place.
[q] identify which of the following is a method used by some bacteria to locomote.
[a] rotation of the flagella.
[q] determine which of the following is true of movement.
I. it is the change in position or location of the body or parts of the body of an organism relative to its surroundings
II. it is always voluntary
III. it can occur in response to internal or external stimuli
IV. only motile organisms move
[a] I and III only.
[q] identify which of the following statements is true of antagonistic muscles:
I. when one muscle in an antagonistic pair contracts, the other relaxes.
II. all muscles have an antagonistic pair.
III. the biceps and triceps are an example of an antagonistic muscle pair.
IV. antagonistic muscles work together to create movement in opposite directions.
[a] I, III and IV only.
[q] determine which of the following changes occur to the structure of a sarcomere when it contracts.
I. Z discs move closer together.
II. H bands increase in length.
III. I bands increase in length.
IV. a band decreases in length.
[a] I only.
[q] identify which of the following are correct functions of skeletons.
I. protect internal organs.
II. provide anchorage points for muscles.
III. contract to allow movement.
IV. act as levers.
[a] I, II and IV only.
[q] determine which of the following statements describes an abduction movement.
I. bending the elbow to touch the shoulder with the hand.
II. raising the arms out to the sides away from the body.
III. pushing the knees together.
IV. straightening a bent leg.
[a] II only.
[q] the diagram shows some structures in the thorax.
identify the labels on the diagram.
[a] I – clavicle
II – ribs
III – external intercostals
IV internal intercostals
[q] determine which of the following statements describes the orientation of the internal and external intercostal muscles.
I. the external intercostal muscles are closer to the surface of the body and run in a downwards and forward direction towards the center of the chest.
II. the external intercostal muscles are deeper than the internal intercostal muscles and run in an upwards and forwards direction towards the center of the chest.
III. the internal intercostal muscles run in a downwards and forward direction towards the center of the chest.
IV. the internal intercostal muscles run in an upward and forward direction towards the center of the chest.
[a] I and IV only
[q] identify which of the following would be classified as a marine mammal.
[a] seal.
[q] identify which of the following are reasons an animal would migrate.
I. move to warmer climates.
II. move to breeding or nesting grounds.
III. move to feeding grounds.
IV. to explore new territories.
[a] I, II and III only.
[q] determine which of the following are features of marine mammals.
I. give birth to live young and nurse their young with milk.
III. hairless for all stages of their life.
IV. breathe through lungs.
[q] identify which of the following adaptations allow marine mammals to stay underwater for extended periods of time.
[a] larger lungs relative to their body size.
[q] which section of the diagram represents myosin filaments alone (where there is no actin overlap)?
[a] IV
[q] which of the following is not a function of the chitinous exoskeleton of arthropods?
[a] deterring predator attack.
[q] what is the sliding filament model of muscle contraction?
[a] a model that explains how filaments within muscle fibers slide past each other to produce movement.
[q] state the name of this type of neuron
[a] motor neuron.
[q] a patient is diagnosed with dupuytren’s contracture, which is a thickening of the tissue layer beneath the skin in the hands and wrist.
what is a test that a doctor might carry out to determine if their ability to move their wrist joints are deteriorating over time?
[a] range of motion test with a goniometer.
[q] which of the following are not characteristics of synovial joints?
[a] absence of cartilage which helps reduce friction and wear.
[q] what structure within muscle tissue is surrounded by a membrane and is multinucleate?
[a] muscle fibre.
[q] what are the two main protein filaments involved in the sliding filament model of muscle contraction?
[a] myosin and actin.
[q] which of the following is not an outcome of skeletal muscle contraction?
[a] myosin filaments slide over the Z-line.
[q] which of the following is an example of a hinge joint?
[a] knee joint.
[q] which of the following statements is correct about antagonistic pairs of muscles?
[a] when the flexor muscle contracts, the limb bends at the joint.
[q] what is the role of titin in muscle relaxation?
[a] titin helps to reset the position of the myosin and actin filaments to their original positions after contraction.
[q] during skeletal muscle contraction, calcium ions are released.
what is the role of calcium ions in muscle contraction?
[a] binding to troponin which causes tropomyosin to move .
[q] what adaptations allow sea anemones to move even though they are sessile organisms?
[a] the ability to contract and expand their bodies rapidly.
[q] Motile Species
[a] Species that are free moving and have the ability to escape predation.
[q] sessile species
[a] These are species that do not move; usually organisms attached to something.
[a] muscle fiber.
[q] Structure of striated muscle cells
[a] Consist of many tubular myofibrils, divided into sections called sarcomeres.
[q] sarcolem
[a] plasma membrane of a muscle fiber.
[q] sarcoplastic reticulum
[a] a specialized type of smooth ER that regulates the calcium ion concentration in the cytoplasm of striated muscle cells.
[q] Sarcoplasm
[a] cytoplasm of a muscle cell.
[q] sarcomere
[a] a structural unit of a myofibril in striated muscle, consisting of a dark band and the nearer half of each adjacent pale band.
[q] before muscle contraction
[a] Neuron action potential reaches the neuromuscular junction/synapse. Release acetylcholine, which attaches to receptor molecules on the cell membrane. This opens the cell’s sodium channels, and the sodium ions move in, generating muscle action potential.
[q] start of contraction
[a] Muscle .potential causes a release of calcium ions from SR into the sarcoplasm. Ca binds to troponin which displaces the tropomyosin on the actin filaments. The myosin binding sites are exposed.
[a] Calcium is pumped back into SR. Troponin gets attached to tropomyosin and covers the myosin binding sites. ATP to myosin, and myosin heads are detached from actin.
[q] antagonist muscle
[a] The muscle opposite the agonist, which must relax and lengthen during contraction of the agonist.
[q] Titin
[a] A series elastic component protein responsible for allowing the sarcomere to stretch and recoil.
[q] motor unit in skeletal muscle
[a] all the muscle fibers controlled by a single motor neuron.
[q] endoskeleton
[a] muscles attached bone to another bone.
[q] exoskeleton
[a] muscles attached to the insides of exoskeleton.
[q] tendons
[a] Connect muscle to bone.
[q] ligaments
[a] Hold joints in place (Connect bone to bone).
[q] synovial joints contain
[q] joint capsule of synovial joint
[a] fibrous membrane that encloses and entire joint.
[q] hinge joint
[a]
[q] planar joint
[a]
[q] saddle joint
[a]
[q] pivot joint
[a]
[q] adaptations for swimming in marine animals
[a] streamlined body, flippers, flukes, dorsal fin, no body hair, blubber, airways that allow periodic breathing.
[q] reasons for locomotion
[a] foraging for food, escaping danger, searching for a mate, migration.
[q] Adaptations for movement as a universal feature of living organisms
[a] Students should understand how a sarcomere contracts by the sliding of actin and myosin filaments.
[q] Role of the protein titin and antagonistic muscles in muscle relaxation
[a] The immense protein titin helps sarcomeres to recoil after stretching and also prevents overstretching.
Antagonistic muscles are needed because muscle tissue can only exert force when it contracts.
[q] Structure and function of motor units in skeletal muscle
[a] Include the motor neuron, muscle fibres and the neuromuscular junctions that connect them.
[q] Roles of skeletons as anchorage for muscles and as levers
[a] Students should appreciate that arthropods have exoskeletons and vertebrates have endoskeletons.
[q] Movement at a synovial joint
[a] Include the roles of bones, cartilage, synovial fluid, ligaments, muscles and tendons. Use the human hip joint as an example. Students are not name the femur and pelvis.
[q] Range of motion of a joint
[a] Application of skills: Students should compare the range of motion of a joint in a number of dimensions. Students should measure joint angles using computer analysis of images or a goniometer.
[q] Internal and external intercostal muscles as an example of antagonistic muscle action to facilitate internal body movements
[a] Students should appreciate that the different orientations of muscle fibres in the internal and external layers of intercostal muscles mean that they move the ribcage in opposite directions and that, when one of these layers contracts, it stretches the other, storing potential energy in the sarcomere protein titin.
[q] Reasons for locomotion
[a] Include foraging for food, escaping from danger, searching for a mate and migration, with at least one example of each.
[q] Adaptations for swimming in marine mammals
[a] Include streamlining, adaptation of limbs to form flippers and of the tail to form a fluke with up-and-down movement, and changes to the airways to allow periodic breathing between dives.
[q] B3.3.1—Adaptations for movement as a universal feature of living organisms
Students should explore the concept of movement by considering a range of organisms including one motile and one sessile species.
[a] Movement is a function of life.
Mobility is the ability of an organism to locomote and move from one location to another.
Motility is a characteristic of all organisms whereby they independently move using metabolic energy. (i.e. peristalsis and segmentation in the digestive tract are forms of motility in humans)
Sessility refers to a trait by which an organism is fixed in its location and unable to move. (i.e. plants are sessile since they are fixed in the ground but are motile due to their tropisms) All organisms are motile, but not all are mobile.
[q] B3.3.9—Reasons for locomotion
Include foraging for food, escaping from danger, searching for a mate and migration, with at least one example of each.
[a] • Foraging for food: bees fly to search for nectar, predators move to catch prey.
• Escaping from danger: prey (like rabbits) move to escape danger.
• Mate searching: to avoid inbreeding, animals travel to search for mates.
• Migration: birds migrate during colder seasons.
[q] B3.3.10—Adaptations for swimming in marine mammals
Include streamlining, adaptation of limbs to form flippers and of the tail to form a fluke with upand-down movement, and changes to the airways to allow periodic breathing between dives.
[a] • Streamlining: marine animals are shaped to minimize water resistance by reducing drag and friction through smooth + hairless skin and tapering towards the rear.
• Adapted limbs: marine limbs form flippers to allow for steering, and their fluked tails with up-anddown movement provides increased thrust.
• Airways: the mouth and lungs are not connected (like in humans), and the blowhole enables them to breathe.
[q] B3.3.4—Structure and function of motor units in skeletal muscle
Include the motor neuron, muscle fibres and the neuromuscular junctions that connect them.
[a] Muscles are composed of muscle fibers, which are made of myofibrils.
A neuromuscular junction is a synapse connecting the axon terminal of a motor neuron and the sarcolemma of a muscle fiber using acetylcholine (Ach) as the neurotransmitter in order to pass the electrical signal to the muscle and cause contraction. Transmitting the action potential to the muscle causes Ca2+ ions to be released from the sarcoplasmic reticulum, initiating muscle contraction.
[q] B3.3.2—Sliding filament model of muscle contraction
Students should understand how a sarcomere contracts by the sliding of actin and myosin filaments.
[a] Sarcomeres are the functional unit of muscles.
Muscle contraction is the shortening of muscle fibers, which involves crossbridge cycle:
• Ca2+ ions bind to troponin to change the conformation of tropomyosin in order to expose and uncover the myosin binding-sites on the actin filaments
• The myosin head needs to power up before binding to actin, so ATP hydrolysis occurs to produce ADP + Pi, which releases some energy that is used by myosin to move its head backwards into a high energy state (it becomes “cocked”)
• With now enough energy, myosin attaches to actin, triggering the release of the stored energy in myosin and prompting ADP and Pi to detach from myosin. This causes the myosin head to bend, which slides the actin towards the H-zone (this is called the power stroke)
• Myosin remains attached to actin until a new ATP molecule binds to it, dismantling the cross-bridge between myosin and actin
• ATP is hydrolyzed to ADP + Pi, returning myosin back to its “cocked” position, repeating the cycle
[q] B3.3.2—Sliding filament model of muscle contraction
Students should understand how a sarcomere contracts by the sliding of actin and myosin filaments.
[a]
[q] B3.3.3—Role of the protein titin and antagonistic muscles in muscle relaxation
The immense protein titin helps sarcomeres to recoil after stretching and also prevents overstretching. Antagonistic muscles are needed because muscle tissue can only exert force when it contracts.
[a] Titin is the largest known polypeptide and has several functions:
• Connects the myosin filaments with the Z-line and ensures they are fixed in the correct place
• Elastic and stores potential energy useful during recoil after contraction
• Prevents overstretching of sarcomere
Since muscles can only pull and not push, when a muscle contracts the other relaxes (they act as antagonistic pairs) in order to ensure controlled force and movement. Antagonism is not an intrinsic property of a specific muscle; it depends on which muscle is currently contracting.
[q] B3.3.5—Roles of skeletons as anchorage for muscles and as levers
Students should appreciate that arthropods have exoskeletons and vertebrates have endoskeletons.
[a] Arthropods (i.e. spiders and crabs) have exoskeletons and vertebrates have endoskeletons. Joints act as fulcrums, bones as levers, and muscles exert force to produce a bone movement whose range of motion depends on the type of joint.
[q] B3.3.6—Movement at a synovial joint
Include the roles of bones, cartilage, synovial fluid, ligaments, muscles and tendons. Use the human hip joint as an example. Students are not required to name muscles and ligaments, but they should be able to name the femur and pelvis.
[a]
Figure 3: hip joint anatomy (Gordon Betts)
• Bones: act as levers and their shape (multiaxial ball-and-socket) determines range of motion.
• Cartilage: reduce friction between bones and absorbs shock.
• Synovial fluid: reduces friction and lubricates.
• Ligaments: collagen-rich to help prevent dislocations and damage from abnormal movements.
• Tendons: attach bone to muscle and provide tensile strength.
• Muscles: provide the force that causes movement.
[q] B3.3.7—Range of motion of a joint
Application of skills: Students should compare the range of motion of a joint in a number of dimensions. Students should measure joint angles using computer analysis of images or a goniometer.
[a] The range of motion of a joint is determined by its structure, and can be measured using computer analysis of images or a goniometer.
[q] B3.3.8—Internal and external intercostal muscles as an example of antagonistic muscle action to facilitate internal body movements
Students should appreciate that the different orientations of muscle fibres in the internal and external layers of intercostal muscles mean that they move the ribcage in opposite directions and that, when one of these layers contracts, it stretches the other, storing potential energy in the sarcomere protein titin.
[a]
When internal intercostal muscles contract, external intercostals relax and the ribcage moves inwards and downwards.
When external intercostal muscles contract, internal intercostals relax and the ribcage moves outwards and upwards.
In either case, the relaxed intercostal (stretched by the contracted one) stores potential energy through titin
[x] Exit text
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