PNS anatomy
Which side of the spinal cord is responsible for sending motor commands?
Ventral
Nocioreceptors: sense pain, extreme heat, located in skin, visceral organs,
Thermoreceptors: sense temperature, typically in skin
Chemoreceptors: sense chemicals, tounge, nose, blood chemistry
Photoreceptors: sense light energy, retina
Mechanoreceptors: sense tactile touch, pressure, vibration, mainly in skin
Proprioceptors: sense body positon, movement and stretch of muscles, associated with muscles
What is the origins of the sympathetic and parasympathetic systems?
Sympathetic- Thoracolumbar
Parasympathetic- Craniosacral
Which receptors bind ACh?
Nicotonic
Between what sections are lateral horns located and what do they do?
T1-L2; it is the main center for the sympathetic division of the autonomic nervous system. Made up of cell bodies
What fiber type is located in the ventral horns?
Interneurons and somatic motor neurons
What is Hiltons law?
Any nerve that supplies a joint and muscle also innervates the muscles that Move that joint as well as the skin covering that joint.
How are the sympathetic and parasympathetic pre and postganglionic axons different?
Sympathetic: Short pre, Long post
Parasympathetic: Long pre, Short post
Which receptors can have either a excitatory or inhibitory effect?
Muscarinic
What is referred pain?
What structure is responsible for anchoring the spinal cord to the coccyx
Filum Terminale
Describe the steps of a reflex arc
1. A stimulus activates a sensory receptor
2. Sensory neuron relays signals to Cns
3. Information from the signal is processed in the integration center by interneurons
4. Motor neuron relays signals from the Cns to an effector
5. Effector responds to signal from the motor neuron
Where do most of the parasympathetic fibers originate from?
Vagus nerve
What structure is “the boss” of the ANS?
Hypothalamus
What is the name for fast adapting receptors and slow adapting receptors? Where are they present?
Tonic- Slow; Pain receptors, proprioceptors
Phasic- Quick; Touch, smell
What is a dermatome?
An area of skin supplied by a spinal nerve. The only spinal nerve that does not participate is C1.
Describe the 3 levels of sensory integration systems.
Circuit level: processing in ascending pathways
Perceptual levels: Processing in cortical sensory areas
Where are the ganglia for Sympathetic and Parasympathetic located?
Sympathetic: Near spinal cord
Parasympathetic: In or near organ
What are neurons that synthesize and release ACh termed? What are neurons that synthesize and release NE termed?
Ach- Cholinergic
Ne- adrenergic
Which system uses gray and white rami communicantes?
Sympathetic
How many pairs of spinal nerves do we have and name how many belong to each section?
31 pairs.
Cervical 8
Thoracic 12
Lumbar 5
Sacral 5
Coccygeal 1
Describe the causes and general purposes of the reflexes.
Stretch reflex: occurs when a muscle stretch’s too far, maintains posture. Initiated by muscle spindle proprioceptor
Tendon reflex: prevents tensing or contracting excessively, causes muscle relaxing. initiated by tendon organ proprioceptor.
Withdrawal Reflex: withdraws body away from pain, initiated by nocioreceptors detecting Pain
Crossed Extensor Reflex: Associated with withdrawal reflex, occurs in the other limb that is not experiencing the withdrawl reflex. Maintains balance and prevents falls.
What are the 3 types of ganglia associated with the autonomic nervous system?
Terminal ganglia: Parasympathetic. Within walls of organ or close to organ
Sympathetic trunk ganglia: sympathetic. Paired, beside spinal cord
Collateral ganglia: sympatheti. Anterior to spinal cord
what is the most common alpha receptor and what is its general effect?
Alpha 1, generally excitatory, Vascoconstion, increases sweat, goosebumps, contracts iris (Dilates pupil)
Which adrenergic receptor specifically increases heart rate?
Beta 1