Intergrative mechanism pt 2 autonomic NS

• 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

• 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

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

• 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

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)

• 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

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)

Sympathetic‘fight or flight’ • Increases heart rate • Bronchodilation • Increases gut motility & secretion • Increases heart contractility • Bladder contraction

Parasympathetic‘rest and digest’ • Decreases heart rate • Bronchoconstriction • Glucose mobilization • Decreases gut motility & secretion • Bladder relaxation

Example- Baroflex