Molecular component for muscle withdrawal

The central nervous system starts the sub-atomic compression of muscles. The motor neuron in the spinal cord’s ventral horn is enacted, starting an upward activity potential that is passed on to the motor end plates of the fibres of the muscle. The activity potential at that point discharges parcels of acetylcholine to the muscle strands synaptic clefts causing electrical resting potential then navigates into the muscle filaments. The spreading of acetylcholine prompts sarcoplasmic reticulum production of calcium particles. The produced calcium particles prompts Troponin and tropomyosin developments in the thin fibers subsequently empowering the molecule heads of myosin to get through the thin fibers henceforth the main impetus for the constriction of muscles.

B. What happens during rigor mortis that results in all skeletal muscles contracting after death?

The cross bridging of actin and myosin in the muscle fibers with the help of calcium ions leads to the contraction of muscles. The cell membranes of muscles become more permeable to calcium ions after death hence causing continued contraction. TP is used to relax the muscles in a normal living organism and it requires respiration in order to be functional. However, after death, the ATP do not last long hence causing a semi permanent contraction resulting in al the skeletal muscles contracting.

2.

A) A table to compare fast-twitch to slow-twitch muscle fibers

B) Differences noted on the table based on the different physiology of these muscles fibers.

The slow-twitched muscles have significantly increased amounts of mitochondria compared to the fast-twitched muscles since they use so much energy. In the same regard, their high consumption of energy requires them to have increases oxygen requirement to facilitate respiration and reduce the rate of fatigue compared to the fast-twitch muscles. Slow-twitch muscles are commonly found in Endotherms due to the high-energy capacity requirements compared to their ectotherm counterparts.

3.

A) Steps involved in the conduction of information along one neuron

Conduction of information begins from the action potential formation. The depolarization of the cell membranes pas the threshold of excitation leads to the opening of ion channels hence the formation of action potential.

The sodium ions channel closes and the potassium ion channels are opened hence the hyper polarization of the cell membranes as the potassium ions leaves the cell membrane.

The action potential then travels down the axon and this follows the depolarization and repolarization of the axon’s membrane. The movement of information in the neuron is enhanced by Nodes of Ranvier that contain potassium and sodium ion channels, which allows the action potential to quickly travel and relay information down the axon from one node to the next in the neurons.

B) How do vertebrates increase the speed of their nerve transmissions?

Vertebrates have the capacity to change their membrane potential since their membranes are electrically excitable, forming the basis for nerve impulses. The sodium and potassium channels of the cell of vertebrates are voltage gated hence can open and close depending on the voltage of the crossing the cell membranes allowing them to increases the speed of their nerve transmission.

4.

A) Components of the synapse that can be modulated to either increase or decrease responsiveness

1. Presynaptic ending; contains packets of chemical neurotransmitters released on the arrival of impulse from the nerve.
2. Synaptic cleft; a short gap between the nerve cells
3. Postsynaptic ending; have specialized receptors that accept neurotransmitters in a lock and key manner.

B) How they can be modulated to produce different effects on cells (for example, the effect that each drug has on the function of the synapse).

Pilocarpine acts as an acetylcholine agonist. On the muscarinic receptors of the synapse between the post-ganglionic fibers and the effector organs, this drug mimics the action of acetylcholine.

Some drugs such as atracurium acts as antagonists of acetylcholine. They block the nicotinic receptors that are present in the junctions of neuromuscular. At this point, such drugs compete with the acetylcholine hence paralysis of the muscles.

Nicotine affects the neurons by increasing the number of synaptic vesicles released.

Drugs such as alcohol alters the membranes of the neurons receptors, ions channels and enzymes. It also directly binds to the receptors of the serotonin, acetylcholine, glutamate and gamma aminobutyric acid.

C) Different potential targets for pharmaceutical and psychoactive drugs to act on the synapse.

• Acetylcholine – control muscles and regulates memory through the many neurons in the brain.
• GABA (gamma-aminobutyric acid) – brains major inhibitory neurotransmitter
• Serotonin – involved in functions such as mood, appetite, and sensory reception

5.If action potentials are all-or-nothing, then

A) Function of graded excitatory and inhibitory postsynaptic potentials

Graded excitatory postsynaptic potentials makes the potentials of the cell membranes to be more positive hence enabling the postsynaptic cell to have more chances of producing an action potential.

Graded inhibitory postsynaptic potentials makes the cell membranes to be more negative hence reducing the chances of the action potential.

B) How is the intensity of the stimulus coded into action potentials

The code for the strength of stimulus is not amplitude modulated. Therefore, when a greater strength of stimulus is applied on the neuron, it produces action potential that is identical and this is produced more frequently per second hence the intensity of the stimulus code is frequently modulated.

6. 6 types of stimuli that animals can detect and provide a brief description of how the sensory receptor works to convert the stimulus into a nerve impulse

1. Light is a stimulus that is detected and transmitted by the photoreceptors in the eyes.
2. Sound is a stimulus that is detected and transmitted by the vibration receptors in the ears.
3. Touch, pain, temperature and pressure are detected and transmitted into nerve impulse by deferent receptors in the skin
4. Taste is a stimulus that is detected and transmitted into a nerve impulse by the tongue receptors.
5. Position of the body is transmitted into a nerve impulse by receptors in the ears.
6. Smell is transmitted into nerve impulses by the nose receptors.

Works Cited

Adds, Philip J, and Somayyeh Shahsavari. The Musculoskeletal System. New York: Informa Healthcare, 2012. Print.

Bradley, P B, and B N. Dhawan. Drugs and Central Synaptic Transmission. London: Macmillan, 1976. Print.

Taylor-Butler, Christine. The Nervous System. New York: Children's Press, 2008. Print.