1.) Physical sensation is a complicated process that involves many parts of the nervous system.
Physical sensations are registered by sensory receptors located in multiple parts of the body.
These sensory receptors send the information they collect in the form of nerve impulses (also
called action potentials) via the nervous system’s ascending (or afferent) tracts which travel
through the cells of the spinal cord and to the brain. The effector for sensory neurons receiving
the physical stimulus would be the structure that responds to it such as a gland that is then
triggered to secrete a hormone.
2.) The pathway of a sensory impulse is as follows: the sensory receptor receives information
via some type of stimulation. That information moves through an afferent neuron and its
ganglion (also known as the dorsal root) and to the spinal cord. From there it travels through an
ascending tract to the brain via a chain of neurons. Each of these neurons has dendrites, cell
bodies, and axons. The impulse is received first by the channels located on the dendrites which
direct the impulse to the cell body. The cell body through electrical graded potential activates
action potential once the trigger threshold is reached. When this occurs the action potential may
travel down the axon towards the synaptic bulb. Within the bulb synaptic vesicles containing
chemical messengers called neurotransmitters move into the synaptic cleft which is in a gap
between the end of one neuron and the beginning of another. Once neurotransmitters are in this
gap they bind to associated ion channels which then stimulates the next neuron to produce
another signal and travel through the nervous system further.
3.) Skeletal muscle movement is mainly controlled by motor neurons. Skeletal muscle
movement is a voluntary process meaning that an individual consciously decides to engage in
its function. The brain sends an impulse through descending (efferent) tracts in the nervous
system through the spinal cord and spinal nerves to the effectors, which in this case is the
skeletal muscles themselves. These tracts are sometimes also referred to as ventral roots and
do not pass through a cell ganglion unlike ascending tracts. However the ascending and
descending are similar in that they are both made up of a chain of neurons that each have a
dendrites, cell body, and axon that use graded and action potentials to allow the information to
travel through the pathways with the help of neurotransmitters. Motor units are made up of
mortar neurons and the muscle fibers it innervates, in other words a motor neuron and the
muscle fiber that it is responsible for sending impulses to.
4.) Standing up is much more complicated than one may think as it requires both leg muscles
but trunk and abdominal muscles as well. Some of the actions that may be required to stand up
(depending on starting position are trunk flexion, abdominal compression, vertebral column
flexion, thigh flexion, extension, adduction, and abduction, knee flexion and extension. Some of
the major muscles that can accommodate these actions respectively are the Rectus Abdominis,
the External Oblique, the Internal Oblique, the Transverse Abdominis, the Psoas Major, the
Iliacus, the Gluteus Maximus, the Piriformis, the Tensor Fasciae Latae, the Adductor Longus,
the Adductor Magnus, the Gracilis, the Sartorius, the Quadriceps Femoris, the Hamstrings, and
the Gastrocnemius.
Physical sensations are registered by sensory receptors located in multiple parts of the body.
These sensory receptors send the information they collect in the form of nerve impulses (also
called action potentials) via the nervous system’s ascending (or afferent) tracts which travel
through the cells of the spinal cord and to the brain. The effector for sensory neurons receiving
the physical stimulus would be the structure that responds to it such as a gland that is then
triggered to secrete a hormone.
2.) The pathway of a sensory impulse is as follows: the sensory receptor receives information
via some type of stimulation. That information moves through an afferent neuron and its
ganglion (also known as the dorsal root) and to the spinal cord. From there it travels through an
ascending tract to the brain via a chain of neurons. Each of these neurons has dendrites, cell
bodies, and axons. The impulse is received first by the channels located on the dendrites which
direct the impulse to the cell body. The cell body through electrical graded potential activates
action potential once the trigger threshold is reached. When this occurs the action potential may
travel down the axon towards the synaptic bulb. Within the bulb synaptic vesicles containing
chemical messengers called neurotransmitters move into the synaptic cleft which is in a gap
between the end of one neuron and the beginning of another. Once neurotransmitters are in this
gap they bind to associated ion channels which then stimulates the next neuron to produce
another signal and travel through the nervous system further.
3.) Skeletal muscle movement is mainly controlled by motor neurons. Skeletal muscle
movement is a voluntary process meaning that an individual consciously decides to engage in
its function. The brain sends an impulse through descending (efferent) tracts in the nervous
system through the spinal cord and spinal nerves to the effectors, which in this case is the
skeletal muscles themselves. These tracts are sometimes also referred to as ventral roots and
do not pass through a cell ganglion unlike ascending tracts. However the ascending and
descending are similar in that they are both made up of a chain of neurons that each have a
dendrites, cell body, and axon that use graded and action potentials to allow the information to
travel through the pathways with the help of neurotransmitters. Motor units are made up of
mortar neurons and the muscle fibers it innervates, in other words a motor neuron and the
muscle fiber that it is responsible for sending impulses to.
4.) Standing up is much more complicated than one may think as it requires both leg muscles
but trunk and abdominal muscles as well. Some of the actions that may be required to stand up
(depending on starting position are trunk flexion, abdominal compression, vertebral column
flexion, thigh flexion, extension, adduction, and abduction, knee flexion and extension. Some of
the major muscles that can accommodate these actions respectively are the Rectus Abdominis,
the External Oblique, the Internal Oblique, the Transverse Abdominis, the Psoas Major, the
Iliacus, the Gluteus Maximus, the Piriformis, the Tensor Fasciae Latae, the Adductor Longus,
the Adductor Magnus, the Gracilis, the Sartorius, the Quadriceps Femoris, the Hamstrings, and
the Gastrocnemius.
