HMS: Nervous System Flashcards
Nervous System
A network of nerves made up of neurons that transmits information w/in the body.
Neuron
A cell that is the functional unit of the nervous system.
Dendrites
Part of the neuron that receives info from other neurons or the environment.
Axon
Part of the neuron that is the pathway for messages (electrical impulses/ action potentials) to be sent to other neurons, muscles, and glands.
Neurolemma
Part of the neuron that is the outermost layer of nerve fiber in the PNS. It serves a protective function. Myelin Sheath lies beneath.
Synaptic Terminals
Part of the neuron that is a junction where messages (electric impulses/ action potentials/chemical) are transferred from one neuron to another, and to non-neuronal cells like those in muscles & glands.
Action Potential
An electro-chemical wave that travels along the axon, provoking a release of neurotransmitter molecules.
Effector Sites
Muscles, glands, and organs that receive messages from the CNS.
Electrolyte
Electrically charged minerals & water that facilitate the transmission of nerve impulses throughout the body. Four primary: sodium, potassium, magnesium & water.
CNS
Brain & Spinal cord responsible for coordinating the activity of all the parts of the body.
PNS
The network of nerves that connect the CNS to the rest of the body and the environment. The PNS allows the CNS to receive sensory input and send a response.
Number of CNS nerves
12 cranial nerves & (31 pair of spinal nerves belong to PNS)
Afferent pathway
PNS sends up sensory information to the CNS
PNS Spinal Nerves, number and loc.
Cervical (c1-c7)
Thoracic (t1-t-12)
Lumbar (l1-l5)
Sacral (s1-s5)
Coccygeal (1)
Efferent Pathway
Also known as motor pathway, it is the way the CNS sends messages down through the rest of the body.
Interneurons
Located only w/i the CNS, they transmit impulses between afferent & efferent neurons.
Sensory Receptors
Structures located throughout the body that convert environmental stimuli into sensory information, send this information via the afferent pathway to the CNS, which uses this information to form a response. Types include!: mechano, noci, photo & chemo.
Mechanoreceptors
Sensory receptors that respond to mechanical forces (touch/ pressure).
Nociceptors
Sensory receptors that respond to pain.
Chemoceptors
Sensory receptors that respond to chemical interaction (smell/ taste).
Photoceptors
Sensory receptors that respond to light (vision).
Somatic Nervous System
Consists of nerves that serve the outer areas of the body & skeletal muscles that is largely responsible for voluntary control of movement.
PNS Classification Tree
PNS consists of two major divisions:
Sensory Nerves (afferent) &
Motor Nerves (efferent)
within Motor Nerves:
Somatic & Autonomic Nervous Systems
the Autonomic Nervous System is divided into:
Sympathetic & Parasympathetic Sys.
Autonomic Nervous System
Supplies neural input to organs that govern the involuntary processes of the body (blood circ., digestion, etc.)
Sympathetic Nervous System
Responsible to increase neural activity and signals endocrine organs to release hormones like adrenaline to increase heart rate, breathing and alertness in anticipation of heightened activity. Fight or Flight.
Parasympathetic Nervous System
Responsible to to decrease neural activity by suspending the release of excitatory hormones, putting the body in a more relaxed state. Rest & Digest.
Primary functions of Nervous System
Provide Sensory, Integrative & Motor function.
Muscle Spindles
Mechanoreceptors within muscles that run PARALLEL to the muscle fibers and are sensitive to changes in muscle LENGTH & rate of change.
Stretch Reflex
When a muscle is stretched the mechanoreceptor muscle spindles are also stretched and report the length and rate of stretch to the CNS, causing the CNS to send a message ordering the muscle to contract in order to prevent excessive lengthening/ injury.
Golgi Tendon organ
Mechanoreceptors located at the point where skeletal muscles insert into the tendons that are sensitive to change in muscular TENSION & the rate of tension change. Activation causes muscle to relax to prevent excessive stress/ injury.
Joint Receptors
Mechanoreceptors in and around joint capsules that respond to pressure, acceleration & deceleration of the joint. Will signal extreme joint positions and initiate an automatic inhibitory response to surrounding muscle if too much stress is placed on that joint.
Neuroplasticity & Neurocircuitry
The concept that the brain will continue to change & grow by reforming neural pathways through lifespan.
Neurocircuitry is the interconnection of neurons in the brain & spinal cord.
Stages in Motor Skill Development
Stage 1: Cognitive. Know goals of the skill & dev. movement strategies, but can only inconsistently perform.
Stage 2: Associative. Practice refines skill, performed w/ less error.
Stage 3: Autonomous. Mastered & can independently modify the skill.
