12: THE NERVOUS SYSTEM Flashcards
How many systems is the nervous system made from
2
The central nervous system
The peripheral nervous system
What is the CNS (central nervous system)
- the main control centre of the body where all information sent from other systems in the body is collected and analysed in prep for a response
what is the peripheral nervous system responsible for
responsible for nerve processes that branch out from the spinal cord and connect with receptors in muscles, glands, blood vessels and organs
what is the somatic nervous system
- part of peripheral nervous system. responsible for all voluntary actions (contracting muscles)
- concerned with the changes in the external environment
- senses movement, touch, pain, skin temp etc
- under conscious coontrol
what is the autonomic system
- part of the peripheral nervous system.
- responsible for involuntary actions (no control) such as digestion, hormonal status, controls cardiac and smooth muscles
- concerned with changes in the internal environment
- not under conscious control
what is the sympathetic system
part of the autonomic system of the peripheral nervous system. the accelerator that speeds everything up eg. if in danger, heart rate goes up)
- fight or flight
what is the parasympathetic system
- acts as the breaks. cool down after work out - reduces heart rate etc
- responsible for decreasing activity and more active during times of relaxation and calm
What are messages or impulses that pass through the nervous system transmitted by?
Nerve cells aka neurons (functional units/information messengers)
What are neurons/nerve cells made up of
- Nucleus
- Main cell body
- Dendrites
- Axon
- Node of ranvier
- Myelin sheath
- Axon terminals
What is the main cell body responsible for
Directing information
What are dendrites responsible for
transmitting information towards the cell body
What is the axon responsible for
transmitting information away from the cell body
What extends from the main cell body
Nerve fibres
the conduction of information along nerves requires the involvement of what
neurotransmitter chemicals produced by nerve cells that allow nerve signals to jump from one cell to the next
What is motor unit recruitment?
Motor unit recruitment refers to the activation of motor units in a muscle.
What is the size principle?
The size principle states that smaller motor units are recruited first, followed by larger ones as the intensity of the contraction increases.
What is the relationship between the rate of motor unit recruitment and the quality of movement?
The rate at which motor units are recruited affects the quality of movement. Slow and controlled movements require a lower rate of motor unit recruitment and are effective for improving stability and control. Fast and explosive movements require a higher rate of motor unit recruitment and are effective for improving power and speed.
Which type of muscle fiber is recruited first and what type of activity is it used for?
Type I (slow-twitch) muscle fibers are recruited first and are used for low-intensity, endurance activities.
Which type of muscle fiber is recruited for high-intensity, explosive activities?
Type II (fast-twitch) muscle fibers are recruited for high-intensity, explosive activities.
what is the all-or-none principle
when a motor unit receives a stimulus of sufficient intensity to bring forth a response, all the muscle fibres within the unit will contract at the same time, and to the maximum possible extent.
What is the neuromuscular connection?
The neuromuscular connection refers to the communication between the nervous system and the muscles it innervates.
What are the effects of exercise on neuromuscular connections?
Exercise can improve the neuromuscular connection by strengthening the synapses between motor neurons and muscle fibers, enhancing motor unit recruitment, and improving coordination.
How does exercise enhance motor unit recruitment?
Exercise can enhance motor unit recruitment by increasing the number of motor units activated during a contraction, improving the synchronization of motor unit firing, and increasing the rate of motor unit recruitment.
What is the relationship between exercise and motor skills?
Exercise can improve motor skills by enhancing neuromuscular connections, improving muscle strength and endurance, increasing coordination, and enhancing proprioception.
what is the function of the nervous system
- the body’s electrical communication system
- monitors change in the internal and external environment
- messages received as a result of these changes needs to be interpreted so the correct response can be made
what is sensory input
monitoring events and changes inside and outside of the body
what is motor output
response to the incoming data
what is the CNS made up of
brain and spinal cord
what is the role of the brain in the CNS
interpreting data and messages recieved
what is the role of the spinal cord in the CNS
responsible for the transfer of messaged in and out of the CNS
what is the peripheral nervous system made of
all the nerves that carry sensory information from the body to the CNS (afferent nerves) and the motor nerves that carry responses to the muscles and organs (efferent nerves)
what are afferent nerves
incoming information about internal or external environmental changes
what are efferent nerves
outgoing information about a response
how do sympathetic nerves work
by releasing a chemical known as a neurotransmitter from the nerve ending to bring about an associated response
what are the effects of the parasympathetic system
- decreased heart rate
- decreased breathing rate
- vasodilation of arteries/arterioles to decrease blood pressure
what are sensory receptors
detect changes in the internal and external environment
what are sensors for changes in the external environment
sight
hearing
touch
smell
taste
pain (somatic)
what are chemoreceptors
detect changes in levels of chemicals such as co2 for respiration and calcium for muscle function
what are thermoreceptors
present in all tissue to detect temperature changes
what are baroreceptors
found mainly in the walls of the arteries to detect changes in blood pressure
what are proprioceptors
found in muscles and tendons to detect changes in body position
how do proprioceptors work in individual muscles
individual muscles have specialised sensory receptors that continually monitor the degree of stretch of tension and relay that info back to the spinal cord and brain
how do proprioceptors work in all the muscles in the body
info coming from all the muscles in the body are coordinated to give the brain an accurate and precise picture of the spatial arrangement of the body
how do proprioceptors work in the brain
the brain, via the spinal cord, sends messages to the muscles to either relax or contract so that correct body position can occur
what are muscle spindles
Almost every muscle contains muscle spindles. These delicate sensory receptors inform the central nervous system (CNS) about changes in the length of individual muscles and the speed of stretching.
what is the reflex arc of muscles being contracted
- the muscle is initially stretched
- afferent signals are sent to the spinal cord
- the signal is interpreted
- efferent motor nerves stimulate the muscle to contract
what is plyometric exercise
power training that combines speed and strength. based on the understanding that concentric muscular contraction is much stronger if it is immediately followed by an eccentric contraction of the same muscle - any movement when a rapid deceleration of the body is followed by a rapid acceleration in the opposite direction
what are the phases of plyometric training
- Pre-stretch or eccentric muscle action. elastic energy is created and stored
- Amortisation phase - short period of time between the end of the pre-stretch and the start of the concentric muscle action (the shorter this phase is, the more powerful the subsequent muscle contraction will be)
- The actual muscle contraction
what are golgi tendon organs
responsible for detecting excessive muscle tension or contraction
work in the opposite way to the muscle spindles
what do golgi tendon organs do
they protect the tendons through a mechanism called the golgi tendon organ reflex. if the muscle contraction is too strong, it puts the muscle tendon at risk of tearing. The GTO detect and monitor the degree of force exerted against the tendon by a contracting muscle. The GTO fire off inhibitory signals via interneurons of the CNA which stops the transmission of motor signals and therefor stops the contraction
what are neurons
an electrically excitable cell that processes and transmits info by electrical and chemical signalling
what is the cell body
contains nucleus which contains the DNA of the cell and regulates cell activity
what are dendrites
tree-like extensions that receive information from other neurons and send those messages to the cell body
what is the axon
elongated fibre that transmits information away from the cell body to the axon terminal
what is the node of ranvier
allows nutrients and waste products to enter/leave the cell. allows nerve impulses to move along the neuron through the process of depolarisation and repolarisation of the nerve membrane.
what is myelin sheath
a fatty sheath that covers the axon, acting as an insulator so that electrical messages can be sent quickly and easily
what is the axon terminals
aka synaptic terminals. containing hundreds of sacs containing different chemicals called neurotransmitters
what is a nerve impulse
an electrical signal that travels along the axon of a neuron
What is the role of neurons in transmitting nerve impulses?
Neurons are specialized cells that transmit nerve impulses. They receive signals from other neurons or sensory receptors, process the information, and transmit it to other neurons or target cells.
What is the resting membrane potential of a neuron?
The resting membrane potential of a neuron is the electrical charge difference across its cell membrane when it is not transmitting a nerve impulse.
What is an action potential?
An action potential is a rapid and brief change in the electrical potential of a neuron’s membrane. It is the basis for transmitting nerve impulses.
What is depolarization?
Depolarization refers to the shift in the electrical charge across a neuron’s membrane toward a more positive value. It is an essential step in generating an action potential.
What is repolarization?
Repolarization is the process in which the electrical charge of a neuron’s membrane is restored to its resting state after depolarization. It involves the movement of ions across the membrane.
What is the role of sodium and potassium ions in generating an action potential?
Sodium ions (Na+) and potassium ions (K+) play crucial roles in generating an action potential. During depolarization, sodium ions rush into the neuron, causing a rapid rise in membrane potential. During repolarization, potassium ions move out of the neuron, restoring the resting membrane potential.
What is the all-or-none principle in relation to action potentials?
The all-or-none principle states that once a stimulus reaches a threshold level, the neuron will fire an action potential with a consistent magnitude and duration. If the stimulus is below the threshold, no action potential will occur.
what is a synapse
the point at which a neuron impulse is transmitted across the gap (between one nerve cell and the next)
how do nerve impulses cross the synapse
electrical impulses must be converted into chemical form. vesicles containing neurotransmitters move into the synapse where they release the neurotransmitters. These are repackaged in a form that can be carried across a gap. Receptor cells on the next neuron are activated to receive and convert the chemical neutransmitters to an electrical impulse.
What is firing threshold?
Firing threshold is the minimum level of depolarization that a neuron must reach in order to generate an action potential.
How does the firing threshold differ in fast twitch motor units compared to slow twitch motor units?
The firing threshold of fast twitch motor units is generally higher than that of slow twitch motor units. They require a stronger depolarization to reach the firing threshold and initiate an action potential
What is the significance of a higher firing threshold in fast twitch motor units?
The higher firing threshold in fast twitch motor units allows them to be selectively recruited for more forceful and explosive movements. These motor units are typically activated when greater force production is needed, such as during activities like sprinting or weightlifting.
How does motor unit recruitment occur?
Motor unit recruitment occurs in a hierarchical manner based on the size and type of motor units. Smaller, low-threshold motor units are recruited first, followed by larger, high-threshold motor units as the demand for force increases.
What is the size principle in motor unit recruitment?
The size principle states that motor units are recruited in order of their size, from smallest to largest. Smaller motor units with lower force-generating capacity are recruited first, and larger motor units with higher force-generating capacity are recruited later.
what are some adaptations of the nervous system with regular training
- development of new and strengthening of existing neural connections
- increased speed and frequency of nerve impulses to stimulate stronger muscle contractions
- improved synchronisation of motor recruitment to achieve muscle contractions
- better muscular coordination to improve application of force
- better muscular coordination to improve application of force
- common movement patterns become automatic
- improved balance due to improved motor recruitment patterns
- improved spatial awareness due to improved neutral connections
- improved speed due to increased frequency and strength of nervous impulses
- improved agility due to improved speed and frequency of signal and neural connections
