neurophysiology concepts and hw

What is functional synergism? How has this been demonstrated through the admission of drugs and Heart rate?

Functional synergism is when an organ is dual innervated like the heart, so the parasympathetic and sympathetic system work together to produce an effort. At rest for heart rate the parasympathetic system is more dominate than the sympathetic but the sympathetic is still activated. This is demonstrated through the admission of drugs when someone is given atropine their parasympathetic system is inhibited raising HR, and then later adding propanol, which inhibits their sympathetic system, with the atropine, both systems are blocked. This leaving only the intrinsic heart rate, thus proving that both systems contributing to heart rate because if the sympathetic wasn’t activated then their would be no reaction.

List the possible motor functions played by the pyramidal, extrapyramidal tract, and the cerebellum. Include function, origin, and if it cross overs, and 2 components for cerebellum.

Pyramidal (corticospinal) track: function is more fine motor control like movement of the eyes, its voluntary origin is the motor cortex crosses over in the lower medulla so it affects the opposite side of the body and ends on the alpha motor neurons in the spinal cord.

Extrapyramidal (brain stem) tract: function is to help maintain balance, posture, and coordinate large muscle groups. It originates in the brain stem and includes the recticulospinal, vestibulospinal, and tectospinal. Cross overs does not occur so it effects the same side of the body.

The cerebellum: function is to coordinate movements and helps with learning new motor control but does not initiate movements. The 2 components are the cortex which sends an output to the deep nuclei (the 2nd component) which sends an output to the cerebellum.

What is a motor unit and what are the 3 primary sources of input to alpha motor neurons?

A motor unit is a motor neuron and all the muscle fibers it innervates. The 3 primary sources of input are the dorsal ganglion root that sends sensory inputs of the muscle spindle, signals from motor neurons in the brain primarily from the cerebral cortex’s gyrus, and finally the inhibitory or excitatory signal from interneurons in the spinal cord (the largest input).

What neural adaptations might explain the early increase in strength with resistance training, and where might these adaptations occur within the nervous system?

An early increase in strength is mainly due to neural adaptations instead of hypertrophy. Some of the adaptations are an increase in recruitment because the more signals sent the more activation of motor neurons, increase in rate coding because there is less inhibition from the spinal cord, and an improvement in the efficiency of the alpha motor neurons by lowering the threshold needed for action potential to occur. All of these adaptations can occur in the brain, spinal cord through interneuron activity, and the motor unit itself.

What are muscle spindles and what do they detect? What about GTO?

Muscle spindles are specialized receptors located within the intrafusal fibers of the muscles. They detect the amount and rate of lengthening of the muscles, which is then sent to the CNS to help regulate movement.

GTO are tension sensors located in the tendons near the muscle-tendon junction. They detect the amount of force/ tension that is being produced by the muscle. If the tension becomes too large, the GTO then starts to send inhibitory signals to the alpha motor neuron so the muscle relaxes and prevents injury.

Discuss muscle contraction from the neuron to the release of Ca at the SR.

To begin a motor neurons action potential travels down the axon to the nerve terminal. This causes the release of ACh which then binds to the nicotinic receptors on the end plate creating an end plate potential (EPP). When the EPP depolarizes the surrounding membrane another action potential is triggered. The action potential then travels down the t-tubules opening the voltages gated Ca+ channels releasing Ca+ from the SR.

ACh is the neurotransmitter for

Preganglioninc sympathetic neurons and motor neurons

Which of the following occurs as a result of tapping one’s patellar tendon

Both alpha motor neurons stimulate contraction of extrafusal fibers in extensor muscles and alpha motor neurons that innervate ipsilateral flexor muscles are inhibited

The cerebellum

Both it’s important for coordinating body movement and has a cortex

Golgi tendon organs

Both are located in the tendons joining the muscle and bone and monitor the strength of muscle contractions

The corticospinal pathways

Are descending motor pathways

Exocytosis of neurotransmitters into the synaptic cleft is trigger by an influx of ______ in response to the arrival of an action potential in the axon terminal

Ca2+

Which of the following characteristic is not attributed to the sympathetic division of the ANS?

Preganglionic neurons tend to be long, with the ganglion located in or near the effector target tissues

The portion of the peripheral nervous system that is composed of verve fibers that innervate skeletal muscle is the

Somatic motor nervous system

The central nervous system include the

Brain and spinal cord

Intrafusal muscle fibers

Are found in muscle spindles