Question

Motor nerve impulses pass from a neuron to a muscle cell ________.   

		carried by neurotransmitters
		across neuromuscular junctions
		across a synapse
		using acetylcholine
		all of the choices

Sarcomeres contain thin filaments of ________ and thick filaments of ________.  

		fast fibers, slow fibers
		actin, myosin
		hemoglobin, myoglobin
		troponin, tropomyosin
		creatine, adenosine

The muscular system consists of all the following EXCEPT

		sarcomeres
		myofillaments
		tendons
		Voluntary striated skeletal muscle fibers
		Voluntary smooth muscle cells
		Involuntary striated cardiac muscle fibers

Skeletal muscle contractions are controlled by___ that stimulate or inhibit contraction of sarcomeres.

		neuroglia
		motor neurons
		mitochondria
		myoglobins

Answer 1

Q1.All of these

During a Muscle Contraction-

Motor neurons carry Impulse ,Which reach the Axon terminal (Pre synaptic Membrane)---There is opening of Voltage gated Ca2+ channels---Influx of ca2+,This Causes binding of Synaptic vesicels that contain neurotransmitter like Acetyl choline,to the pre synaptic membrane,Fuses with it--Release Neurotransmitter(Acetyl choline) to Synaptic cleft,Binds to Acetyl choline receptors in the muscle sarcolemma(Post synaptic membrane),causes influx of Na+---Resting membrane potential become less negative---Opening of Voltage gated sodium Channels [when Potential reaches thredhold potential for Na+ channel]--Depolarisation in the sarcolemma---ca2+ release from Sarcoplasmic reticulum---Muscle contraction.

The junction between presynaptic and post synaptic membrane is called Synapse.

Since here a motor neuron is connecting nerve impulse to muscle it is also called Neuromuscular junction

Q2.Option 2-Actin & Myosin.

The contractile proteins in Skeletal muscles are Actin ,in the thin filaments & Myosin in the Thick Filaments.

Troponin and Tropomyosin are regulatory proteins in muscle contraction,associated with Actin filament.

Q3.Option 5-Voluntary smooth muscles.

Muscle involves Skeletal muscles,Cardiac muscles and Smooth muscles,Of which Cardiac muscles and Smooth muscles are involuntary(Not under Voluntary Control) but Skeletal muscles are under Voluntary control.

Tendons attaches skeletal system to muscular system by connecting Muscles to Joints.

Sarcomere is the contractile unit of a muscle fibre.

Myofilaments are filaments in the muscle formed by Actin or Myosin

Q4.Motor neurons.

Skeletal muscle contraction are controlled by motor neurons,that Carry impulse from CNS to Muscle through a neuromuscular Junction (Synapse).

Motor Neurons Can be Excitatory or Inhibitory.When Excitatory it causes wave of depolarisation in the sarcolemma which causes calcium release from Sarcoplasmic reticulum---which eventually leads to Muscle contraction.

But Motor neurons can sometime be Inhibitory to Muscle contraction,which makes the muscle to relax