Comparing Latency Periods And Amplitude Periods

* A stretch reflex is a contraction of a muscle when an attached tendon is pulled. Stretch reflexes are important in maintaining proper posture. Stretch reflexes are used to determine which areas of the body the central nervous system are not responding to. For example, if you tap your knee to check for reflex and the leg doesn’t move, you then know that the peripheral nerves that lead to the knee are nonresponsive and/or the brain is not receiving a signal from that particular area.

The spinal cord is the final common pathway from the brain to the muscles. It controls all the sensory inputs received from different locations throughout the body. The spinal cord also controls voluntary muscle responses. Some elementary reflexes are local to the spinal cord, but voluntary muscle

The nervous system is responsible for registering extrinsic and intrinsic factors and communicating them with the entirety of the body. Dendrites acquire these signals from other neurons and then the signal is transmitted through the cell body and down the axon. Graded potentials create an electrical charge that eventually leads to threshold being met and action potentials being generated. These action potentials send the signals down the axon. Signals will sometimes struggle to hike up stream due to threshold recently being met. This absolute refractory state inhibits signals from traveling up the axon unless myelin is present to increase signaling. It takes longer to conduct a signal down an un-myelinated axon because voltage-gated ion channels

What levels of spinal nerves would need to be intact in order for Matt to still have a patellar (knee-jerk) reflex? Explain the mechanism of the patellar reflex. Include the muscles and nerves involved. What would an absence of a patellar reflex or diminished patellar reflex entail? What is the clinical term for the absence/decrease of this reflex? What

Lightly myelinated Aδ fibers and unmyelinated C fibers have thinner axons and a higher threshold of activation. Nociceptors of Aδ fibers can be either mechanosensitive or thermosensitive. Polymodal nociceptors (of C fibers), may respond to both mechanical and thermal stimuli, as well as chemicals [261-263]. When nociceptors are activated, the fibers transmit action potentials along the axon to the spinal cord [264, 265]. The spinal cord mediates sensory and motor communication between the periphery and the brain, and is organized into four regions; cervical, thoracic, lumbar, and sacral. The gray matter contains cell bodies of neurons and glia and is divided into the dorsal horn, intermediate column, lateral horn, and ventral horn. The dorsal horn is comprised of sensory nuclei that receive and process incoming sensory information [266], and like the rest of the spinal gray matter, is organized histologically into parallel laminae based on the size and density of neurons [267]. In general, laminae I to IV are involved in exteroceptive sensation whereas laminae V and VI are involved in proprioceptive sensations [263]. Nociceptors terminate in the dorsal horn laminae in a

Review Sheet Results 1. Describe how increasing the stimulus frequency affected the force developed by the isolated whole skeletal muscle in this activity. How well did the results compare with your prediction? Your answer: When the stimulus frequency was at the lowest the force was at its lowest level out of all of the experiments. As the stimulus frequency was increased to 130, s/s the force increased slightly but fused tetanus developed at the higher frequency. When the stimulus frequency was increased to the amounts of 146-150 s/s, the force reached a plateau and maximal tetanic tension occurred, where no further increases in force occur from additional stimulus frequency. 2. Indicate what type of force was developed by the isolated skeletal muscle in this activity at the following stimulus frequencies: at 50 stimuli/sec, at 140 stimuli/sec, and above 146 stimuli/sec. Your answer: At 50- Unfused

Facilitation occurs when postsynaptic potentials evoked by a stimulus are increased when that stimulus closely follows a pervious stimulus. Five stimulus pulses were given at decreasing interpulse intervals. The data for this experimenet displays that when the interpulse interval changes from 10msec to 8 msec, the number of pulses needed to reach the maximum MAP increases rather than the expexted outcome. This is most likely due to movement of the muscle in the chamber, causing the recordings to be reading different areas of the muscle. Different neuromuscular junctions in the muscle require different amounts of Ach in order for muscle action potentials to reach threshold.

A three-neuron reflex arc consists of a receptor, a sensory (afferent) neuron, and a motor (efferent) neuron. The reflex arc is designed to help keep the body safe, and is the mechanism that permits immediate responses to danger related stimuli. A conduction pathway of a reflex arc consists of the motor neuron innervation of the peripheral nervous system, and at least one association neuron from the central nervous system. After the conduction pathway, an impulse follows. The reflex arc is composed of a sensory receptor, sensory nerve, integrating center, motor nerve, and effector organ.

Every minute of the day, there are billions of sensory information that neurons collect and translate into action potentials and neurotransmitters. Depending on the stimulus, the action potential could change in amplitude, frequency, and velocity. This phenomenon is an allusion to what I have done in lab. Increasing the stimulus would increase amplitude, frequency, and decrease the time duration. A classic example that is related to the experiment I have performed is pinching the skin. When we were all little kids, pinching was a generic behavior done when someone made us angry. However, pinching is pertinent to the electric stimulus that was used on the earthworm's nerve cord. When someone gets pinched, stretch receptors detect this information

Reflexes are the infant’s most obvious organized patterns of behavior. A reflex is an unlearned, involuntary, automatic response to a particular form of stimulation. A wide variety of reflexes are seen in infants during the last four months of prenatal life and the first four months after birth. Reflexes also occur subcortically, which means “below the level of cortex of the brain.” (282 MD) Reflexive movements are therefore without direct involvement of the higher brain centers. Reflexes are an important role to infants, they are used for protection, nutrition, survival and development of voluntary movement. Reflexes are an interesting subject that I learned in my motor development class this semester as well as in this lifespan development class. I found it fascinating that we as humans use reflexes to survive and eventually they help us learn to function.

It gives motor supply to both supra and infraspinatus muscles (9,10). In this study we will highlight various pulse sequences for selective nerve visualization as well as their functional evaluation. We aimed at studying the different patterns of muscle denervation in addition to their relation to the shape and SI of the related nerves. Finally correlation between the signal changes in different types of nerve injuries and the findings of the nerve conduction study as well as the patient’s clinical history will also be discussed.

Question 2.) When you step on a tack it stimulates an automatic response in the body called the reflex arc. These reflexes arise in the spinal cord without the help of the brain. The pain would first be detected in the foot by a sensory neuron with sends a message to the spinal cord. A sensory neuron is a neuron that carries a messages from the senses to the central nervous system. Once the message is in the spinal cord is synapses with a connector neuron. A connector neuron links two neurons together. This connector neuron then activates a motor neuron which is a neuron that carries messages from the central nervous system to the muscles and glands. Then the message reaches the effector neurons in the muscle fibers, and effector neurons are neurons capable of producing a response. The muscle cells then contract causing you to pull your foot away from the tack.

The compound action potential adds up all the action potentials that each individual neuron experiences in the sciatic nerve. Different stimulus amplitudes cause different neurons to fire an action potential; this is due to the fact that each neuron has a different threshold potential, or the minimum voltage the neuron needs to fire an action potential. The individual neuron action potential is an ‘all-or-nothing’ event, but the CAP, as a summation of different individual neurons, is not. The CAP amplitude will increase with larger stimulus potentials because more neurons with higher individual thresholds will be recruited. For this frog sciatic nerve, there are three fiber types, A, B, and C. A fibers are further divided, in the order of decreasing diameter, into α, β, γ, and δ fibers. There is an inverse relationship between the diameter of the nerve fiber and the threshold potential: the larger the diameter, the lower the threshold. Thus, as the largest fibers, the Aα neurons will be the first to be stimulated at a low stimulus potential, and the Aδ neuron fibers will be the last to be recruited. Because the sciatic nerve is mostly composed of A fibers, the recruitment of A-subtype nerve fibers are more readily distinguishable from the data. The minimum potential required to stimulate the Aα fibers was between 75 mV and 80 mV. Once the stimulus potential reached 90 mV, Aβ neurons were recruited and contributed to the increase in amplitude of the CAP. At a stimulus

There are two groups of reflexes in the human body, with two ways to categorize each of them. Reflexes can either be inborn and connected through the nervous system, or they can be learned through practice. Another way to explain a reflexive category would be autonomic reflexes or somatic reflexes. Autonomic reflexes are those which are unaware to us and act on visceral organs of the body, whereas somatic reflexes involve skeletal muscle stimulation. Both types of reflexes are put into effect via the nervous system. (1)

Reaction time is the time between the presentation of a stimulus and the initiation of the muscular response to that stimulus ( the free dictionary [26/07/14].The purpose of this test was to identify what happens to reaction times as different independent variables are applied. The nervous system helps all parts of the body to communicate with each other, it is responsible for making sure all of the body’s parts coordinate properly. The nervous system is the centre of all the body’s activity (better health channel [26/07/14]). The brain and spinal cord make up the central nervous system and all the other nerves in the body part of the peripheral nervous system. Inside nerves lie neurons, neurons are found in the brain, spinal cord and the peripheral nerves (PubMed Health [26/07/14]). They are also known as nerve cells. These neurons have the same structure as plant and animal cells (differencebetween.net [27/07/14]). Neurons are made up of a cell body, dendrites, a nucleus, an axon and a myelin sheath (the nervous system [27/07/14]). The myelin sheath surrounds the nerve fibre of axon and protects the body from the electrical charge that nerves have (GCSE Bite size [27/07/14]). There are two types of neurons: sensory neurons and motor neurons. Sensory neurons send signals to the brain and spinal