SNS Biology - Muscles and Locomotion Flashcards
1
Q
Locomotion
Unicellular
A
- Protozoans and algae - cilia or flagella
- Amoebae - pseudopodia
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
3
Q
Pseudopodia
A
Forward extension of the cell membrane, allowing the cell to move
4
Q
Locomotion
Invertebrates
A
- Hydrostatic Skeletons:
Flatworms
Segmented worms (annelids)
- Exoskeleton
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
6
Q
Locomotion
Invertebrates
Hydrostatic Skeletons
Annelids
A
- Same as for flatworms
- ach segment can expand or contract independently
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
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
9
Q
Vertebrate Skeleton
Bone
A
- Mineralised connective tissue
- Has ability to withstand stress and provide body support
- Two types:
- 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
- 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
10
Q
Vertebrate Skeleton
Bone
Osteocytes
A
Two types
- Osteoblasts - synthesise and secrete organic constituents of bone matrix. Once surrounded by bone matrix mature into osteocytes
- Osteoclasts - large, multinucleated cells. Involved in bone resorption
11
Q
Vertebrate Skeleton
Bone
Formation
A
- Endochondral Ossification - eg long bones
- Intermembraneous - mesenchymal (undifferentiated) connective tissue transformed into bone
12
Q
Vertebrate Skeleton
Bone
- Axial Skeleton
- Appendicular Skeleton
A
- Basic framework of body. Consists of vertebral column, skull, rib cage. Point of attachment for the appendicular skeleton
- Includes bones of appendages and pectoral and pelvic girdles
13
Q
Vertebrate Skeleton
Bone
- Ligaments
- Tendons
A
- Bone to bone connectors
- Attach muscle to bone and bend the skeleton at moveable joints
14
Q
Muscle
Innervation
- Skeletal Muscle
- Cardial Muscle
- Smooth Muscle
A
- Somatic nervous system
- Autonomic nervous system
- Autonomic Nervous system
15
Q
Muscle
Appearance
- Skeletal
- Cardiac
- Smooth
A
- Multinucleated, striated, formed from the fusion of several mononucleated embryonic cells, abundant mitochondria
- Single central nucleus, lack striations
- Striated, one or two centrally located nuclei
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
- Sarcoplasm
- Sarcolemma
A
- Cytoplasm of a muscle fibre
- 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
- Z lines define border of a single sarcomere and anchor the thin filaments
- M line runs down the centre of the sarcomere
- I band is region containing thin filaments only
- H zone is the region containing thick filaments only
- 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
- Latent period - time between stimulation and onset of contraction. AP spreads along the sarcolemma, Ca2+ released into sarcoplasm
- Contraction period
- 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
- Creatine Phosphate - in vertebrates and some invertebrates, energy can be temporarily stored in this high-energy compound
- Arginine Phosphate - similar to above. Utilised by invertebrates
- Myoglobin - haemoglobin-like protein. Has high O2 affinity and maintains supply in muscles. Can subsequently be used to generate ATP via cellular respiration
