Compendium Review Ch.13

Table of contents:
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
Neuron
Axon
Myelin Sheath
Sensory neuron
Motor neuron
Resting potential
Action potential
Synapse


The central nervous system and the peripheral nervous system are a combination of two systems which together receive information from the body, take the data and integrate into the spin or brain for analyzing the data, and then provide output in the form of either organ reaction or muscle contraction.


Central Nervous System (CNS):

Spinal Cord: The spinal cord provides a connection between the brain and the peripheral nerves.

Brain: The brain is divided into two hemispheres with some connected tissues in between them. The brain is responsible for reasoning, memory, language, and speech, as well as all upper level cognitive processing. Each hemisphere has four lobes for brain functions, frontal, parietal, occipital, and temporal.

The Diencephalon: The important task of keeping the body regulated and maintaining homeostasis is controlled by the hypothalamus.

The Cerebellum: The cerebellum takes in information from the senses and cerebral cortex to determine the position of the bodies limbs. After processing the information the cerebellum sends signals to the skeletal system for movement.

The Brain Stem: The brain stems primary function is to use the medulla oblongata and regulate breathing and the heartbeat.


Peripheral Nervous System (PNS): The peripheral nervous system is responsible for taking impulses from nerves and transmitting them to the brain and spinal cord. The PNS is composed entirely of nerves and ganglia. The PNS is made of two other systems the somatic system and the autonomic system.

Somatic System: Consists of functions that we control consciously or can occur by natural reflex which we still have some cognitive control over. The somatic system consists of the skin, skeletal muscles and tendons which can be controlled by reflex (automatic) or voluntary where the brain process information in the cerebral cortex.

Autonomic System: This system consists of the functions which are involuntary and are done automatically by processing in the brain. These functions include the organs and there processes and are based on cellular processing and impulses. Breathing and the heart pumping blood are good examples of autonomic functions. Within this system there are two other division the sympathetic division which has body responses in times of stress and the parasympathetic division which has reactions in times of relaxation.


Neuron: Neurons provide the path for nerve impulses to travel threw the body to the spinal cord or brain. Neurons uses axon as the pathway for transmitting the nerve signal, and dendrites which receive signals from other neurons or sensory receptors.

Axon: The axon is the part of a neuron which the nerve impulse travels along. The axon can extend from the nerve or neuron the entire length of the body and connect to the spinal cord.
Myelin Sheath: Protects the axon by insulating portions of the axon. The Myelin also allows the nerve signal to travel along the axon quicker by jumping over portions of where the myelin sheath is covered.

Sensory neuron: Are neurons that develop as you are very young and will stay with you for your entire life. The sensory neuron is dedicated to receiving nerve signals and transmitting them to the spinal cord.

Motor neuron: Are dedicated to taking instructions from the brain and spinal cord to a muscle or limb allowing the muscle to contract and perform human functions.

Resting Potential : When the axon does not have a nerve signal traveling threw it there is a negative charge of -65 mV inside the axon. Inside the axon there is a greater concentration of potassium ions (k+) then outside. Outside the axon there is a greater concentration of sodium ions (Na-) then on the inside this creates a negative charge when no signal is traveling threw. The amount of sodium and potassium ions inside and outside of the axon is controlled by gates which allows one or the other of the two ions to move in an out (sodium-potassium pump). The membrane of the axon is also permeable to potassium ions allowing them to move easily back into the axon.

Action Potential: When a nerve signal is traveling threw an axon as it approaches then next portion of the axon the sodium-potassium pump activates and pushes out sodium ions and takes in potassium ions to have a net positive charge of +40 mV inside the axon membrane. This process allows the signal to travel along the axon at 1/1000 of a second. After the signal has passed through that portion of the axon it depolarizes and goes back to the resting potential. When we talk about the negative and positive charges of the axon there is no middle voltage potential either the axon is a resting or action potential. Depending on how strong the nerve impulse is will tell how many impulses travel in rapid succession (frequency).

Synapse: The synapse is the function which allows the signal from the sending neuron to transmit its data to the receiving neuron threw the synaptic cleft. This process uses synaptic vesicles to enclose the neurotransmitter cross the synaptic cleft and pass threw the receiving neurons neurotransmitter receptor.