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Biol 101 > Lecture 14 > Flashcards

Lecture 14 Flashcards

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1
Q

Pariapulid worms (3)

A

marine, known since Cambrian period, found in BC

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2
Q

What is Nematomorpha? (4)

A

parasitic larvae, can reach 2 m long, adults are free-living, horsehair worms

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3
Q

Loricifera (3)

A

very small, live in marine sediments, found in 1980s

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4
Q

Tradigrades

A

“water bear”, survive in extreme temperature

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5
Q

Onychophora

A

“velvet worm”, paralyze the prey

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6
Q

Arthropods are the most diverse eukaryotic group (4)

A
  1. Beetles
  2. Crustaceans
  3. Spiders
  4. insects
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7
Q

Diversity Examples - Arthropods (5)

A
  1. Myriapodes
  2. Scorpian
  3. Sea spider
  4. Amphipode
  5. Scolopendra
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8
Q

Insects - Dysticus

A

predaceous diving beetle, adult collect air under wings and use this to breathe underwater

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9
Q

Honey bees

A

highly complex social life - worker bees dance to communicate

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10
Q

Characteristics - Arthropods (4)

A
  1. largest eukaryotic group
  2. very abundant
  3. Grouped segments
  4. Jointed appendages for specialized function (rigid exoskeleton)
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11
Q

Tagmata

A

grouped segments, specialized body region

ex. Cephalothorax and abdomen (crayfish)

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12
Q 
Rigid exoskeleton (6) 
(made of? secreted by? covers? alive? process?)
A
  • grow by moulting
  • non-living
  • secreted by epidermis
  • covers all external surfaces, digestive tract & trachea
  • composed of layers
  • Chitin, protein + CaCO3
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13
Q

Discontinous growth

A

mass grows continuously but size grows in stepwise

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14
Q

Types of Skeleton (3) Examples within each one

A
  1. Hydrostatic skeleton (ex. cnidarian, worms, shell-less mollusks)
  2. Exoskeleton (Ex. shelled mollusks, arthropods)
  3. Endoskeleton (Ex. Echinoderms, vertebrates)
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15
Q

Skeleton muscles - Arthropods (3)

A

muscles within appendage

  • need a resistor to act against (like a skeleton)
  • are often found in antagonist pair, act in opposite direction, muscle can only pull not push
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16
Q

What is muscle organ and muscle fibre?

A

muscle organ: muscle tissues and connective tissue

A muscle fibre is a multinucleated cells that contain many myofibrils

17
Q

Myofibrils (muscle)

A
  • composed of protein bundles
    (actin - thin, myosin thick)
  • myofibrils make up the sacromere
18
Q

Sarcomere

A

contractile unit of muscle fibres

19
Q

Motor neuron

A
  • motor neuron spikes drive muscle contractions at neuromuscular junction
20
Q

What is neuromuscular junction?

A
  • synapse between the motor neuron and the muscle fibre
21
Q

What happens when spike reaches neuromuscular junction?

A
  1. Action potential reaches synapse (neuromuscular junction) Voltage-gated Ca+++ channels open and Ca++ flow into presynaptic terminal
  2. Increased concentration of Ca++ leads to the fusion of synaptic vesicles containing neurotransmitter with presynaptic membrane (neurotransmitter at neuromuscular junction is acetylcholine)
    Transmitter reaches receptor proteins on postsynaptic membrane via diffusion
    These receptors are ligand-gated ion channels (their ligands is acetylcholine): some Na+ flows into muscle cell, depolarizing it
  3. Voltage-gated Na+ channels open and action potential is generated in muscle cell membrane, travels into depth of muscle fiber via T-tubules
    Acetylcholine is broken down to acetic acid and choline by enzymes acetylcholine-esterase; components taken back up into presynaptic terminal for re-use
22
Q

Contraction of sarcomere

A

caused by sliding of thick filament (myosin) with thin filaments (actin)

23
Q

Low (Ca+++)

A

= myosin head cannot bind to actin filaments

- Tropomyosin and Troponin work together to block the myosin binding sites on actin

24
Q

High (Ca+++)

A

= myosin binding sites of actin become exposed

- when a calcium ion binds to troponin, the troponin-tropomyosin complex moves, exposing myosin binding sites

25
Q

Muscle action

A
  • When the muscle is relaxed, myosin is not binded to actin
  • when muscle is in action, myosin can now bind to actin - actin and myosin become more overlapped
  • A single spike in a motor neuron causes a single excitatory postsynpatic potential (EDSP) spikes in the associated muscle fibers, followed by a single twitch
  • During contraction, length of actin and myosin does not change, the amount of overlapping does
26
Q

How does an entire muscle contract?

A

Force generated by entire muscle depends on

  • Number of motor units (aka motor neuron + associated muscle fibres) activated
  • frequency at which motor units are firing
27
Q

Motor units in vertebrates

A

For vertebrate skeletal muscle, each muscle fiber is innervated by a single motor neuron, but each motor neuron innervates many muscle fibers

28
Q

Types of Muscles

A

Skeletal muscle
Cardiac muscles
Smooth muscle

29
Q

Skeletal muscle

A
  • striated
  • multinucleated
  • cylindrical
  • attached to bone via tendon
30
Q

Cardiac muscles

A
  • striated
  • branched in shape, allows it to within high pressure
  • Gap junctions btwn cells allow synchronized contraction
  • smaller than skeleton muscle cells, have only one nucleus
31
Q

Smooth muscle

A
  • blood vessel, digestive tract
  • actin and myosin is not regularly arranged, so does not appear striated
  • long, spindle shape with a single nucleus
32
Q

Muscle Summary

A
  • Movement is based on antagonistic muscle groups that act on a skeleton.
  • Muscle tissue is composed of several muscle fibres, that are composed of myofibrils, composed of successions of sarcomeres.
  • Muscle contraction happens when myosin proteins move down the length of actin fibres.
  • Calcium ions play an essential role in muscle contraction, by making the actin in thin filament available for binding by myosin.
  • In animals with exoskeletons or endoskeletons, muscle are usually arranged in opposing pairs of flexors and extensors.

Biol 101 (17 decks)

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