BIO 212 Exam 3

• Types of animal movement

  • Movement of one part of the animal relative to another part
  • Movement of the entire animal relative to its environment (locomotion)
• What is the function of the skeletal system?

  • Protection from physical and biologic intrusions
  • Maintain body posture
  • Transfer muscle forces to other parts of the body and the environment
• Hydrostatic skeleton

  Invertebrates; extensible body wall in fluid tension
• Earthworm movement

  1. Circumferential muscles contract to decrease diameter and increase length

  2. Longitudinal muscles contract to increase diameter and decrease length
• Exoskeleton

  • An exterior skeleton that encloses and protects the body
  • Made up of proteins and chitin (insects)
  • Made up of calcium carbonate (crustaceans)
  • Disadvantages: Limited muscle size and movement, growth requires molting (soft parts are vulnerable)
• Endoskeleton

  • Vertebrates
  • Made of bone, cartilage, and ligaments
  • Composed of rigid levers separated by joints
• Cartilage

  Vertebrate connective tissue that cushions interacting bone surfaces
• Vertebrate movement

  1. Skeletons move by a change in joint angles promoted by the action of antagonistic muscle groups

  2. Flexors pull bones closer together, decreasing joint angles

  3. Extensors increase the angle of a joint, straightening it out
• Muscle fiber

  Long, slender cells that make up muscle tissue
• Sarcomere

  • Made of several proteins organized as filaments
  • Actin composes thin filaments
  • Myosin composes thick filaments
  • Organized as: Full Length of Myosin = A Band, Myosin, No Actin = H zone, Actin, No Myosin = I band, Z-line / Z-disc – anchoring point for actin filaments, M-line – anchoring point for myosin filaments
• Muscle contraction

  1. Filaments slide past each another

  2. Sarcomere shortens with no change in lengths of the thin or thick filaments
• At rest, the myosin cannot bind the actin
• Muscle relaxation

  1. When neurons stop producing action potentials

  2. Acetylcholine broken down by ACHE (AcetylCHoline Esterase)

  3. Ca2+ is actively transported back into sarcoplasmic reticulum
• Ligament

  Vertebrate connective tissue that binds bones to other bones
• Tendon

  Vertebrate connective tissue that attaches skeletal muscle to bone
• Bone diagram

  A) Osteon

  B) Canaliculi

  C) Haversian Canal

  D) Lamellae

  E) Lacunae

  F) Osteocyte

  G) Osteoclast

  H) Osteoblast

  I) Canaliculae

  J) Lamellae

  
• Muscle components

  A) Muscles

  B) Muscle Tissue

  C) Bundle of muscle fibers

  D) cells

  E) Muscle fiber

  F) cell

  G) myofibrils

  H) Myofibril

  I) sarcomeres

  J) Sarcomere

  
• Sarcomere diagram

  A) actin

  B) myosin

  C) Z disk

  
• Muscle contraction

  1. Tropomyosin and troponin block myosin binding sites on actin
  2. Calcium ion binds to troponin, causes complex to move and expose myosin binding sites
  3. ATP binds to myosin head
  4. ATP hydrolized, myosin head grabs new actin subunit
  5. Phosphate released, moves thin actin filament, ADP released
• Taxis


  The movement towards or away from a stimulus
• Types of taxis

  • Chemotaxis (chemical stimulus)
  • Phototaxis (light)
• Stimuli can be classified as

  • Attractants (positive taxis)
  • Repellents (negative taxis)
• How bacteria perform taxis

  1. Run (flagella spinning in a coordinated way, moving in a straight line)

  2. Tumble (flagella spinning in a way that makes the bacteria "spin" in place, changing direction)
• When bacteria want to get somewhere (positive taxis)

  They make long runs and don't tumble very often
• When bacteria are trying to get away from something

  They perform shorter runs and frequent tumbles
• Flagellar motor

  Can rotate in two directions: counterclockwise (smooth run) and clockwise (tumble)
• Tumbles almost always lead to a change in direction
• What can plants sense

  • Light
  • Gravity
  • Pressure
  • Damage
  • Certain airborne molecules ("smell")
  • Nutrients in soil ("taste")
• How signal reception in plants works

  1. Signal receptor proteins change shape in response to an environmental stimulus

  2. This initiates the production of a plant hormone

  3. The hormone is transported to the target cells

  4. The hormone causes a physiological response

  5. The hormone only elicits a response if the cell has an appropriate receptor

  6. Hormone receptors initiate an intracellular signal in a process called signal transduction

  7. A cellular response is executed (activation of membrane transport proteins for change in ion flow, changes in gene expression - transcription or translation)
• Transduction

  The conversion of an external stimulus to an internal signal in the form of action potentials along sensory neurons
• Transmission

  The transmission of the signal to the central nervous system (CNS), different types of sensory information are transmitted to different parts of the CNS.
• Transduction often involves ion channels

  1. Receiving a stimulus initiates ion flow into the sensory cells

  2. If threshold is reached, an action potential is initiated

  3. The action potential is sent to CNS

  5. All action potentials are the same, but each type of sensory neuron sends its signal to a different portion of the brain
• What do hair cells do in the mammalian ear?

  Hair cells specialize in detecting vibrations
• How sound waves are collected and transmitted to the cochlea

  1. The outer ear collects pressure waves and funnels them into the ear canal, where they strike the tympanic membrane

  2. The tympanic membrane vibrates with the same frequency as the sound waves and passes the vibrations to middle ear bones

  3. The vibrations are passed malleus to incus to stapes, which vibrates against the oval window

  4. The oval window generates waves in the fluid inside the cochlea
• How the cochlea detects sound

  1. Waves move the basilar membrane, which pushes the hair cells against the tectorial membrane, causing them to bend

  2. Potassium channels open, potassium flows into the hair cell

  3. Depolarization triggers inflow of calcium ions

  4. Neurotransmitters are released and trigger action potentials in the sensory neuron
• How are different sounds and frequencies distinguished?

  The basilar membrane varies in stiffness; sounds of different frequencies cause the membrane to vibrate most in specific locations.
• Types of photoreceptors

  • Rods (sensitive to dim light but not to color)
  • Cones (stimulated by different wavelengths of light (colors))
• Rhodopsin

  A molecule made of retinal (pigment) and opsin (a protein), found in large quantities in the membrane-rich disks of rods and cones
• How is light sensed in the mammalian eye?

  1. Photoreceptors are NOT receiving light stimulus, neurotransmitters continuously released

  2. cGMP gated Na channels remain open (Na in), allow membrane depolarization. Retina and opsin change shape.

  4. cGMP is converted into GMP, cGMP gated sodium channels close

  5. Membrane is hyperpolarized and neurotransmitters are no longer released. Decrease indicates light absorption, new action potentials.
• Che mechanism - no stimulant

  A) inactive

  B) active

  C) phosphorylated

  D) more

  E) CheY-P

  F) CheY

  G) Tumbles