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DAT > SNS Biology - Muscles and Locomotion > Flashcards

SNS Biology - Muscles and Locomotion Flashcards

1
Q

Locomotion

Unicellular

A
  • Protozoans and algae - cilia or flagella
  • Amoebae - pseudopodia
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2
Q

Cilia and Flagella

A
  • Same structure for all eukaryotic cells
  • Consist of cylindrical stalk of 11 microtubules - 9 paired around circumference, 2 single microtubules in the centre
  • Flagella acheive movement via power stroke - thrusting movement generated by sliding action of microtubules
  • Return of cilia or flagella to starting position called the recovery stroke
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3
Q

Pseudopodia

A

Forward extension of the cell membrane, allowing the cell to move

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4
Q

Locomotion

Invertebrates

A
  1. Hydrostatic Skeletons:

Flatworms

Segmented worms (annelids)

  1. Exoskeleton
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5
Q

Locomotion

Invertebrates

Hydrostatic Skeletons

Flatworms

A
  • Muscles arranged in circular and longitudinal layers.
  • Contract against the resistance of incompressible fluid within the tissues (the hydrostatic skeleton)
  • Contraction of the circular layer causes incompressible fluid to flow longitudinally lengthening the animal
  • Contraction of the longitudinal layer shortens the animal
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6
Q

Locomotion

Invertebrates

Hydrostatic Skeletons

Annelids

A
  • Same as for flatworms
  • ach segment can expand or contract independently
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7
Q

Locomotion

Exoskeleton

A
  • Found principally in arthropods (eg insects)
  • Insect exoskeletons composed of chitin
  • All exoskeletons composed of noncellular material secreted by the epidermis
  • Limit growth, must be shed periodically and new skeleton deposited to permit growth
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8
Q

Vertebrate Skeleton

Cartilage

A
  • Connective tissue
  • Softer and more flexible than bone
  • Retained in adults where firmness and flexibility are necessary, for example the external ear, nose, laryngeal and tracheal walls, skeletal joints
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9
Q

Vertebrate Skeleton

Bone

A
  • Mineralised connective tissue
  • Has ability to withstand stress and provide body support
  • Two types:
  1. Compact - dense. Deposted in osteons or Haversian systems (structural units) consisting of a central Haversian canal surrounded by concentric circles of bony matrix (calcium phosphate) called lamellae
  2. Spongy - much less dense. Consists of interconnecting lattice of trabeculae (bony spicules). Cavities between them are filled with yellow and/or red bone marrow. Yellow marrow is inactive and infilrated by adipose tissue. Red marrow is involved in blood cell formation
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10
Q

Vertebrate Skeleton

Bone

Osteocytes

A

Two types

  1. Osteoblasts - synthesise and secrete organic constituents of bone matrix. Once surrounded by bone matrix mature into osteocytes
  2. Osteoclasts - large, multinucleated cells. Involved in bone resorption
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11
Q

Vertebrate Skeleton

Bone

Formation

A
  1. Endochondral Ossification - eg long bones
  2. Intermembraneous - mesenchymal (undifferentiated) connective tissue transformed into bone
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12
Q

Vertebrate Skeleton

Bone

  1. Axial Skeleton
  2. Appendicular Skeleton
A
  1. Basic framework of body. Consists of vertebral column, skull, rib cage. Point of attachment for the appendicular skeleton
  2. Includes bones of appendages and pectoral and pelvic girdles
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13
Q

Vertebrate Skeleton

Bone

  1. Ligaments
  2. Tendons
A
  1. Bone to bone connectors
  2. Attach muscle to bone and bend the skeleton at moveable joints
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14
Q

Muscle

Innervation

  1. Skeletal Muscle
  2. Cardial Muscle
  3. Smooth Muscle
A
  1. Somatic nervous system
  2. Autonomic nervous system
  3. Autonomic Nervous system
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15
Q

Muscle

Appearance

  1. Skeletal
  2. Cardiac
  3. Smooth
A
  1. Multinucleated, striated, formed from the fusion of several mononucleated embryonic cells, abundant mitochondria
  2. Single central nucleus, lack striations
  3. Striated, one or two centrally located nuclei
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16
Q

Vertebrate Skeleton

Muscle

Skeletal

Structure

A
  • Muscle fibres composed of sarcolemma and parallel bundles of myofibrils, each surrounded by sarcoplasmic reticulum
  • Sarcolemma is connected to T-tubules which provide channels for ion flow throughout the muscle fibres and can propagate the AP
17
Q

Vertebrate Skeleton

Muscle

Skeletal

Structure

Sarcoplasmic Reticulum

A
  • Modified endoplasmic reticulum
  • Envelops myofibrils, stores Ca2+
18
Q

Vertebrate Skeleton

Muscle

Skeletal

Structure

  1. Sarcoplasm
  2. Sarcolemma
A
  1. Cytoplasm of a muscle fibre
  2. Muscle fibre cell membrane. Capable of propagating an AP. COntains T-tubules
19
Q

Vertebrate Skeleton

Muscle

Skeletal

Structure

The Sarcomere

A

Composed of thin and thick filaments composed of actin and myosin filaments respectively

  1. Z lines define border of a single sarcomere and anchor the thin filaments
  2. M line runs down the centre of the sarcomere
  3. I band is region containing thin filaments only
  4. H zone is the region containing thick filaments only
  5. A band spans entire length of the thick filaments and includes regions in which overlap with thin filaments

During contraction A band isn’t reduced in size, H and I are

20
Q

Vertebrate Skeleton

Muscle

Skeletal

Contraction

A
  • Stimulated by somatic NS via motor neurons
  • NT released from presynaptic boutons at NMJ and stimulate postsynaptic receptors
  • If sufficient stimulation, permeability of sarcolemma altered, AP generated
  • AP is conducted along the sarcolemma and T-system into the interior of the muscle fibre
  • Causes release of Ca2+ from the sarcoplasmic reticulum into the sarcoplasm
  • Ca2+ bind to tropomyosin allowing actin and myosin to slide past each other and the sarcomere to contract
21
Q

Vertebrate Skeleton

Muscle

Skeletal

Simple Twitch

A
  • Response of a single muscle fibre to a brief supra-threshold stimulus
  • Consists of
  1. Latent period - time between stimulation and onset of contraction. AP spreads along the sarcolemma, Ca2+ released into sarcoplasm
  2. Contraction period
  3. Relaxation period - muscle briefly unresponsive to stimuli (absolute refractory period)
22
Q

Vertebrate Skeleton

Muscle

Skeletal

Summation

A
  • When muscle fibres exposed to a very frequent stimulus, muscle cannot fully relax
  • Contractions begin to combine - temporal summation
  • Become stronger and more prolonged
23
Q

Vertebrate Skeleton

Muscle

Skeletal

Tetanus

A
  • Continuous contractions of muscle fibres upon high frequency stimulation
  • Stronger than simple twitch of a single fibre
  • If maintained, muscle will eventually fatigue and contraction will weaken
24
Q

Vertebrate Skeleton

Muscle

Skeletal

Tonus

A
  • State of partial contraction
  • Muscles never completely relaxed and maintain partially contracted state
25
Q

Vertebrate Skeleton

Muscle

Cardiac

A
  • Possess characteristics of both smooth and skeletal muscle fibres
  • As for skeletal muscle, actin and myosine filaments arranged into sarcomeres, giving striated appearance
  • Controlled primarily for ANS
26
Q

Vertebrate Skeleton

Muscle

Smooth

A
  • Rensponisble for involuntary muscle contraction
  • Innervated by ANS
  • Found in GI tract, bladder, uterus and BV walls for example
  • Lacks striations
27
Q

Vertebrate Skeleton

Muscle

Energy Reserves

A
  1. Creatine Phosphate - in vertebrates and some invertebrates, energy can be temporarily stored in this high-energy compound
  2. Arginine Phosphate - similar to above. Utilised by invertebrates
  3. Myoglobin - haemoglobin-like protein. Has high O2 affinity and maintains supply in muscles. Can subsequently be used to generate ATP via cellular respiration

DAT (53 decks)

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