02.03.2022-QUIZ 2- BIO 445
Name: Shivam Kumar
Roll No. : 20191128
1. The four distinct phases of the step cycle in cats and humans are :
→ Generating an action potential in the sarcolemma
→ Form a cross-bridge and release a neurotransmitter (Acetylcholine) and calcium ions
in the sarcoplasm.
→ Pulls the attached actin filaments towards the centre of "A" band
→ Remove the masking of active sites for myosin.
The rhythmic alternating contractions of the flexor and extensor muscles of the cat’s leg
will still have smooth movements in all joints, but the amplitude is decreased. The
differences in timing between the hip on the one hand and the knee-ankle on the other
remain, and the support phase may still contain a clear yield phase (flexion) followed
by an extension. In the yield phase occurring after the dorsal root damage, the
contracting extensor muscles must lengthen due to the load on the limb without any
reflex interaction.
2. CPG or Central Pattern Generator is a half-centre organization of flexor and extensor
interneurons.
3. Central pattern generators (CPGs) are biological neural circuits that produce rhythmic
outputs rhythmic input is absent.
An example of one central pattern generator is a multifunctional network of the
Mollusk Tritonia diomedea.
Function: CPG helps in the tightly-coupled patterning of neural activity that drives
rhythmic and stereotyped motor behaviours like walking, swimming, breathing or
chewing.
4. The lamprey central pattern generator (CPG) for locomotion consists of a collection of
neurons in the spinal cord which is responsible for producing the rhythmic neural
activity used for swimming. Mechanoreceptors in the margin of the spinal cord, detect
the bending of the body and provide the necessary sensory feedback for the CPG. Thus,
these mechanoreceptors are essential for the CPG’s ability to respond to perturbations.
5. The sensory information that is used to regulate locomotion is vision, hearing and
touch.
6. Electrical stimulation of MLR in the brain stem of a cat on a treadmill induces controlled
locomotion on a treadmill. But when we increase the intensity of MLR stimulation
violent postures and movements is observed which eventually leads to displacement of
the recording electrode.