Intergrative mechanism pt 2 autonomic NS

Question 1

Learning objectives

Answer 1

•explain in principle how neuronal control occurs
•compare and contrast neuronal and chemical signaling and understand that these control mechanism interact
(pt 1)

• understand the basic functions of the peripheral and central nervous systems
• describe the basic organisationof the autonomic nervous system in relation to parasympathetic and sympathetic nervous activity
• understand the concept of autonomic reflex arcs
• describe and understand the effects of autonomic nervous system activity on organs and organ systems; example: control of heart rate
• refer to the roles of the brainstem in autonomic nervous system coordination;example: the baroreflex

Question 2

What are the 2 components of the nervous system?

Answer 2

• The central nervous system (CNS) –composed of the brain and spinal cord
• The peripheral nervous system (PNS) –composed of all nerves that sense & communicate data to/from the CNS

Question 3

What is the role of the CNS?

Answer 3

Organises, integrates and processes sensory information to produce an appropriate motor response or output

Components: 1. the brain(main data handling centre of the body) consists of
•the cerebrum (regulates higher-level functioning such as thought, emotion, memory)
•the cerebellum(maintains coordination)•the brain stem (includes the midbrain, pons& medulla & controls lower-level (basic) functioning such as breathing, swallowing, heart rate, BP

)2. the spinal cord (information super highway)
•connects the body’s main receptors to the brain
•serves as a conduit for sensory input & motor output

Question 4

What is the role of the PNS?

Answer 4

• Connects the CNS to organs, limbs and skin
• Carries sensory and motor information to and from the CNS
• Allows the brain and spinal cord to receive and send information to other areas of the body
• Regulates involuntary body functions like heartbeat and breathing

Question 5

What is the hierarchy of the NS?

Answer 5

NS> CNS/ PNS

PNS> ANS (communicates w/ internal organs and glands), Som. NS (comm. w sensory organs and voluntary muscle)

ANS> 1. sympathetic division ( arousing) and 2. parasympathetic division ( calming) - Ach in preganglionic p/s neurons
Noradrenaline/ Ach in postganglionic neurons
(Enteric Nervous System (controls the function of the gastrointestinal tract), is sometimes considered part of the ANS and sometimes considered independently)

Som. NS> Sensory ( afferent nervous system, sensory input), Motor (efferent nervous system, motor output)

Question 6

What is the role of the Somatic NS?

Answer 6

• Controls reflex and voluntary actions
• Afferent fibres/nerves carry sensory signals to the CNS for processing
• Efferent fibres carry instructions from the CNS back through the somatic system
• Instructions are sent to the neuromuscular junction for motor output

Question 7

Compare and contrast the somatic and autonomic efferent reflex arc pathways

Answer 7

AE- spinal cord > autonomic presynaptic axon ( myelinated) ( central neuron synapses with ganglionic neuron) > autonomic postsynaptic axon (unmyelinated)> target effector smooth muscle: AXON DOES NOT NECESSARILY SYNAPSE ( POSTGANGLIONIC VARICOSITY)

SE- spinal cord> somatic motor neuron (myelinated) (central fibre projects to target effector) > target effector skeletal muscle ( axon ends at synaptic terminal)

Question 8

What are the roles of the sympathetic NS?

Answer 8

Sympathetic‘fight or flight’

• Increases heart rate
• Bronchodilation
• Increases gut motility & secretion
• Increases heart contractility
• Bladder contraction

Question 9

What are the roles of the parasympathetic NS?

Answer 9

Parasympathetic‘rest and digest’

• Decreases heart rate
• Bronchoconstriction
• Glucose mobilization
• Decreases gut motility & secretion
• Bladder relaxation

Question 10

What is the role of the brainstem in autonomic NS coordination?

Answer 10

Example- Baroflex