Timothy De Guzman
Amy Guavain
March 28, 2012
Lab
1. What components of the nervous system are involved in physical sensation? How does
sensory impulse move throughout the body?
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The Peripheral Nervous System (PNS) is involved with physical sensation. The PNS has
two divisions, the sensory division and the motor division. Sensory Division is mostly
involved with physical sensation for it consists of afferent nerve fibers that run through
the body and into the spine. It conveys impulses from sensory receptors located
throughout the body.
Sensory impulse travels by first being stimulated by a receptor in the skin in which goes
to the sensory neurons that travels through the afferent fibers then goes to the spinal cord
and then finally to the brain.
2. What components of the nervous system are involved in skeletal muscle movement? How
does motor impulse move throughout the body? What is a “motor unit”?
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The motor division or efferent division of the PNS is involved in skeletal muscle
movement. The impulse the motor division receives from the Central Nervous System
transmits the information it receives to contract muscles and secretes glands.
 Motor impulses travels through the body by the efferent nerve fibers. When the brain
processed the right response it send an impulse through the efferent nerve fibers.
 A motor unit is a motor neuron and all the muscle fibers it’s connected to. When motor
neuron transmits an electrical impulse all the muscle fibers it connects contract.
3. What movements are involved in the action of standing up? What muscles need to contract to
perform these actions?
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The muscles that contracts in order to perform the actions are Quadriceps, Hamstrings,
the glute group ( gluteus maximus, minimus and medius) gastrocnemius, plantaris,
soleus, and the tibialis anterior. Quadriceps extends the legs and the hamstrings extends
your hips when you stand. The gluteus maximus is a major extensor of the thigh
straightens your hips when you stand. Gastrocnemuis, plantaris and soleus stabilizes the
lower leg when standing up. The tibialis anterior also functions as a stabilizer of the
lower leg when standing up.
4. What are the different levels of organization of a muscle down to myofilaments? What is a
“sacromere” and how are its proteins organized?
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Muscle, fasicle, muscle fiber, myofibril, myofilament
A Sacromere is the smallest contractile unit of muscle, it extends from one Z disc to the
next. The sacromere has two important proteins one is myosin and it forms the thick
filament. The myosin binds actin and ATP which is the needed for muscle movement.
The other protein is called actin, the actin form the thin filament it appers to be formed by
two intertwined actin filaments that look like a twisted double strand of pearls.
5. Starting from the release of acetylcholine by the motor neuron, what are the steps in muscle
contraction? How is contraction ended?
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First of all for skeletal muscle fiber to contract they need to be stimulated by nerve
ending must extend an action potential along its sarcolemma.