Timothy De Guzman

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?

·  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”?

·  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?

·  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?

·  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.