Blog

A dissection in the aorta involves which layer?

The sarcomere represents the minimal amount of structure necessary to carry out muscle contraction and is referred to as the _______ of skeletal muscle.

The muscle contraction and relaxation caused by a single stimulus is referred to as a ________.

In which skeletal muscle phenomenon would you expect to find an optimal length?

Please put answer in the space provided. 1.  In the figure on the right, identify what is found at the tip of the arrowhead (shown in blue). __________ 2.  In the figure on the left, what is the structure on the far left of the diagram that is shown ascending? ___________ Don’t forget to take Lab Quiz 4 – Muscle tomorrow, March 25th, which is located in a separate part of the Module.  You will not be taking the Quiz today as previously mentioned in an Announcement on Sunday.    

One of the figures presented to you showed the effect of increasing weight on the amplitude of the finger twitch.  How can you describe the shape of that curve? ______

The __________ are responsible for producing the fluid that lubricates the urethra prior to ejaculation. 

Based on what you know about the likely content(s) of the contraceptive birth control pill, briefly explain how it regulates ovulation (or lack thereof) by a negative feedback process.

Using the letters corresponding to the stages in the physiology of muscle contraction, write the events of muscle contraction in chronological order in the space provided. Note:  The first step begins somewhere in the neuron as I want to determine if you still understand some of the steps that take place in the neuron from previous notes.     a. Attachment of another ATP allows the cross bridge to detach from the actin and repeat the cycle over  again as long as Ca2+ remains attached to troponin.    b. Voltage-gated Ca2+ channels open in pre-synaptic terminal and Ca2+ enters cell.    c. Ca2+ attaches to troponin, causing a conformational change in its structure.     d. Action potentials in the T tubule stimulate the release of Ca2+ from the terminal cisternae.    e. ACh diffuses across cleft and binds to ACh receptors.     f. Action potentials stop being produced, SR accumulates calcium and the troponin-tropomyosin complex moves again to its inhibitory position.    g. Binding of ACh to receptors opens up ion channels on muscle cell membrane that causes EPP’s and a      depolarization of the muscle.    h. Myosin cross-bridges bind ATP, attach to actin, and undergo a power stroke.      i. Action potentials are conducted in a motor neuron and arrive at the terminal of the axon.     j. Shape change in troponin causes tropomyosin to shift position in the actin filament, thus exposing binding sites for the myosin cross-bridges.    k. T tubules conduct action potentials deep into the muscle fiber.    l. Ca2+ entry causes the release of ACh at the neuromuscular junction.  m. Action potentials are conducted across the muscle cell membrane.

Conversion of the “indifferent” gonad into a testis depends on the presence of the _________.