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What do General Somatic efferent fibers do?
Carry motor impulses away from CNS to skeletal muscle and stimulates them to contract
What do general visceral efferent fibers do?
Carry motor impulses away from CNS to various smooth muscles and glands associated with internal organs, causing certain muscles to contract or glands to secrete
What do General Somatic afferent fibers do?
Carry sensory impulses toward the CNS from receptors in the skin and skeletal muscles
What do General Visceral afferent fibers do?
Carry sensory impulses toward the CNS from blood vessels and internal organs
What do special somatic efferent fibers do?
Carry motor impulses away from the brain to the muscles used in chewing, swallowing, speaking and forming facial expressions
What do special somatic afferent fibers do?
Carry sensory impulses toward the brain from the receptors of sight, hearing and equilibrium
What do special visceral afferent fibers do?
Carry sensory impulses toward the brain from the olfactory and taste receptors
- Respond to changes in the concentration of chemical substances
- Smell & Taste
- Respond to tissue damage
- Triggering factors include exposure to excess mechanical, electrical, thermal or chemical energy
Sensitive to temperature changes
Describe mechanoreceptors, identify the 3 types & their functions
- Sense mechanical forces by detecting changes that deform the receptor
- Proprioceptors – changes in tensions of muscles & tendons
- Baroreceptors (pressoreceptors) – blood vessels detect changes in BP
- Stretch Receptors – lungs sense degree of inflation
- Found in eyes
- Respond to light energy of sufficient intensity
- Associated with changes at the body surface
- (Touch, Temperature, Pressure & Pain)
- type of sensory nerve ending
Describe interoceptors (visceroreceptors)
- Associated with changes in viscera
- Type of sensory nerve ending
- Associated with changes in muscles and tendons and in body position
- type of sensory nerve ending
Describe free nerve endings
- Consist of terminal branches of sensory nerve fibers lying freely in the innervated tissue
- Appear to mediate thermal, painful and itching sensations
- Unencapsulated exteroreceptor
Describe Meissner's (Tactile) Corpuscles
- Abundant in the hairless portions of the skin (lips, fingertips, palms, soles, nipples and external genital organs)
- Great sensitivity to touch and are thought to be responsible for fine or discriminative touch
- Encapsulated exteroreceptor
Describe Pacinian corpuscles
- Common in deeper dermal tissue of the hands, feet, penis, clitoris, urethra, breasts and also in tendons and ligaments
- Detect heavier pressure and stretch and also vibration in tissues
- Encapsulated exteroreceptor
Describe muscle spindles (a type of proprioceptor)
- Respond to muscle stretch (stretch receptor)
- Located in skeletal muscles near their junctions with tendons
- Detect changes in muscle length
- Important in the control of muscle tone, movement & kinesthesia
Describe golgi tendon organs (type of proprioceptor)
- Found in tendons close to their attachments to muscle
- Detect changes in muscle tension
- Helps maintain posture and protects muscle attachments from being pulled away from theirinsertions by excessive tension
Define sensory adaptation
Ability to ignore unimportant stimuli
Define neuromuscular junction
Site where an axon and muscle fiber meet
Increasing muscle tension by increasing the number of muscle fibers contracting
Define twitch (fasciculation)
Rapid contraction and relaxation of a muscle
Define staircase effect (treppe)
The gradual increase in muscular contraction following rapidly repeated stimulation
Smooth, sustained contraction of skeletal muscle resulting from a rapid series of nerve impulses
Define sustained contraction
A continuous firing of action potentials
Define radial nerve compression
Compression in the spiral groove (post.upper half) of the humerus
Define Chronic entrapment of the Ulnar nerve
Entrapment of the ulnar nerve at the elbow
Compression of what nerve results in carpal tunnel syndrome
Describe the sequence of nerve involvement which takes place in a reflex arc
- Sensory (afferent) neuron
- Interneuron (Link)
- Motor (efferent) neuron
Describe the monosynaptic reflex
- Reflex that uses only two neurons (1 synapse)
- Sensory (afferent) neuron communicating directly with a motor (efferent) neuron
- Ex: Knee-jerk reflex, stretch reflex or deep tendon reflex
Describe the polysynaptic reflex
- Reflex mediated by more than two neurons (many synapses)
- More complete reflex arc
- Ex: Withdrawal reflex, flexor reflex, crossed extensor reflex
What does the CNS consist of?
Brain and spinal cord
What does the PNS consist of?
Spinal nerves and Cranial nerves
What are the functions of the nervous system
sensory, motor & integrative
Structural & functional unit of the nervous system
Supporting or accessory cell in the nervous system
What does the axon do?
Carries impulses away from cell body
What does the dendrite do?
Carries impulses toward cell body
Describe somatic nervous system
Voluntary & supplies skeletal muscle
Describe autonomic nervous system
Visceral, involuntary & supplies smooth & cardiac muscle & glands
Myelin is produced by what?
- CNS: oligodendrocytes
- PNS: Schwann cells
Connects neurons to blood vessels
- produces myelin in CNS
- one cell can myelinate many axons
membrane is electrically charged
Membrane potential is more negative
membrane potential is less negative
Describe electrical conduction
Lets nerve impulses travel rapidly within a neuron and Gives the nervous system therapid-response capability
Describe chemical transmission
Takes place in the synapses between neurons, enabling nerve impulses to be transmitted from one neuron to the next and gives the brain the flexibility that is required for learning
Describe EPSP (excitatory post-synaptic potential)
- Depolarizes membrane of postsynaptic neuron
- Action potential of postsynaptic neuron becomes more likely
Describe IPSP (Inhibitory PostSynaptic Potential)
- Hyperpolarizes membrane of postsynaptic neuron
- Action potential of postsynaptic neuron becomes less likely
Describe Synaptic transmission
- Neurotransmitters are released when the impulse reaches the synaptic knob
- When the action potential passes over the surface of a synaptic knob, the contents of the vesicles (neurotransmitters) are released in response to the presence of calcium ions
Describe the longitudinal fissure
Separates right & left cerebral hemispheres
Describe the Transverse Fissure
Seperates cerebrum from cerebellum
bumps or convolutions of brain
grooves between gyri
Describe the corpus collosum
Connects the cerebral hemispheres at the midline
What does the brainstem consist of
What is the sensory function of the parietal lobe
interprets sensation on the skin
What is the sensory function of the temporal lobe
What is the sensory function of the occipital lobe?
What is the motor function of the frontal lobe?
-of Broca's area?
-of the Frontal eye field?
- Control voluntary muscles
- controls muscles involved in speech
- control voluntary movement of eyes and eyelids
What are the functions of the associated areas of the:
- Concentrating, planning on complex problem solving
- Understanding speech & Choosing words to express thought
- Interprets complex sensory experiences & Stores memories of visual scenes, music & complex patterns
- Analyze and combine visual images with other sensory experiences
What does the Epithalamus consist of, and what are the functions of these structures?
- Pineal Gland – most notable component
- – Endocrine gland
- – Synthesizes melatonin
- -Controls the “sleep-wake” cycle (circadian rhythm)
- -Helps regulate the onset of puberty
- Habenular nuclei
- -Connected with the Limbic system
What are the functions of the Thalamus?
- Main sensory relay center for nervous system
- Gateway for sensory impulses heading to cerebral cortex
- Receives all sensory impulses (except smell)
What are the functions of the hypothalamus?
- Maintains homeostasis by regulating visceral activities
- Links nervous system to endocrine system
What are the functions of the spinal cord?
- Center of Spinal Reflexes
- Conduit for nerve impulses to and from the brain
Where are the cell bodies for sensory pathways located?
Cell bodies are in the dorsal root ganglion
Where are the cell bodies for motor pathways located?
Cell bodies are located in the ventral horn of the spinal cord