Lecture 20 PNS and ANS

Describe the role of sensory receptors in the ascending tracts and describe the types of sensory receptors important to sensation such as free nerve endings, Pacinian corpuscle, Meissner’s corpuscle, and muscle spindles. (13.1)

• Free Nerve Endings- Respond to mechanical simulation

• Pacinian Corpuscles- Respond to pressure and vibratory stimuli 

• Meissner's Corpuscles- Responding to touch and light touch

Muscle Spindles- Responding to stretch and position changes

Map how information travels from the peripheral nervous system into the central (think, dorsal root ganglion, dorsal gray matter, ascending white matter, brain, descending gray matter, ventral horn gray matter, ventral motor root ganglion). (13.2)

• 1. Dorsal root ganglion- sensory neurons transmit information from the skin and other receptors to the spinal cord 

• 2. Spinal cord- axons from the dorsal root ganglion enter the spinal cord where they synapse with second order neurons in the dorsal horn

• 3. Ascending Pathways- these pathways carry sensory information to the brain with the spinothalamic tract and dorsal column-medical lemniscal pathway being major components 

• 4. Thalamus- information from the spinal cord synapses with third order neurons in the thalamus, which then sends signals to the cerebral cortex

• 1. Cerebral Cortex- Finally the information reaches the cerebral cortex where it is processed and integrated into conscious awareness

What are the 4 different nerve plexuses 

• Cervical 

• Brachial

• Sacral

• Lumbar

Where is the general location of the cervical nerve plexuses?

Posterior triangle of the neck 

Where is the general location of the brachial nerve plexuses?

Neck and upper chest

Where is the general location of the sacral nerve plexuses?

Posterior pelvic wall 

Where is the general location of the lumbar nerve plexuses?

Lower back

What are the 4 most important cranial nerves

• Optic nerve- Ability to see 

• Oculomotor nerve- ability to move and blink your eyes

• Trochlear nerve- ability to move yours eyes up and down or back and fort

• Abduceans nerve- ability to move your eyes

What is the general location of the Optic nerve?

Back of the eye 

What is the general location of the Oculomotor nerve?

Midbrain

What is the general location of the Trochlear nerve?

Midbrain

What is the general location of the Abduceans nerve?

Brainstem

What is the special senses group for the optic nerve?

CN II

What is the CN II function?

It sends visual information from the retina to the brain 

What is the special senses group for the oculomotor nerve?

CN III

What is the CN III function?

Controls eye movement and pupil dilation allow for voluntary eye movement 

What is the special senses group for the trochlear nerve?

CN IV

What is the CN IV function?

Controls eye movement towards the nose or away from it 

What is the special senses group for the abduceans nerve?

CN VI

What is the CN VI function?

Controls eye movement from left to right

What is the autonomic nervous system?

Regulates involuntary bodily functions (like heart rate, digestion, and respiratory rate) without conscious control 

What is the peripheral nervous system?

Facilitating communication between the brain and the rest of the body

Compare the somatic and autonomic nervous systems relative to effector organs, efferent pathways, and neurotransmitters released. (14.1)

• The somatic nervous system-

  • Controls voluntary muscle movement and sensory information relay to CNS

  • It consist of motor neurons that send signals to skeletal muscle releasing acetylcholine at the neuromuscular junction 

• Autonomic nervous system

  •  Manages involuntary functions, controlling organs like the heart and glands with pathways involving preganglionic and postganglionic neurons 

  • It releases norepinephrine or epinephrine at the effector organ which influences processes like heart rate and digestion.

• Both systems work together to maintain homeostasis and response to stress or rest.

What is the somatic nervous system?

Controls voluntary movements and processes external stimuli

What are the functions of the parasympathetic division?

• Slowing heart rate

• Stimulation digestion 

• Promoting salivation and lacrimation

• Constricting pupils

• Facilitating urination and defecation

• Regulating sexual function

• Countering stress responses

What are the functions of the Sympathetic division?

• “Fight or flight”

• Increase heart rate

• Dilating pupils

• Inhibiting digestion

• Mobilize the body's resources for immediate action