Chapter 11 efferent division Autonomic

Autonomic Nervous System

involuntary system: controls smooth, cardiac, and many glands

Somatic motor nerves

voluntary system

sympathetic

dominate during stressful or exercise situations

parasympathetic

dominate at rest or sleep

What do hypothalamic pons and medulla control

monitor parameters like osmolarity, body temp, blood pressure, and breathing

Cerebral cortex and limbic system control

send commands to control centers

spinal cord controls

mediates some ANS reflexes without brain input

ex: urination, defecation, and arousal

Antagonistic effects

opposite effects

EX: SNS increases HR and PNS decreases HR

Preganglionic neurons origin

CNS and project to autonomic ganglions

Postganglionic neurons origin

originate in the ganglion and project to the target tissue

ANS ganglion act as

integrating center

Sympathetic pathway origin

thoracic and lumbar regions of spinal cord

parasympathetic pathway origin

brain stem and sacral regions of spinal cord the

Sympathetic: Location of ganglia

close to spinal cord

parasympathetic: location of ganglion

close to target tissue

Sympathetic length of preganglionic and postganglionic cells

short preganglionic and long postganglionic

Parasympathetic length of preganglionic and postganglionic cells

long preganglionic and short postganglionic

Adrenergic receptors

only located on tissues

bind to NE or EPi

can be beta or alpha

Cholinergic receptor

bind Ach

nicotinic on ganglia

muscarinic on tissue

PNS Pathway preganglionic NT and receptors

preganglionic neurons release acetylcholine onto nicotinic cholinergic receptor

PNS pathway postganglionic NT and Receptor

postganglionic neurons release acetylcholine onto muscarinic cholinergic receptor

SNS pathway preganglionic NT and receptors

preganglionic neurons release acetylcholine onto nicotinic cholinergic receptor

SNS pathway postganglionic NT and Receptor

postganglionic neurons release norepinephrine onto the adrenergic receptors alpha and beta

Neuroeffector junctions

the synapse between postganglionic autonomic neurons and non-neural target cell

Varicosities

ANS postganglionic axons are modified into a series of swollen bulbs that release neurotransmitters

Advantage of varicosities

one neuron affects more cells with one command causing a widespread response

Synthesis release and removal of ANS neurotransmitters

1. NE is sythesised in varicosity

2. depolarization of varicosity opens calcium channel

3. calcium influx triggers vesicle release

4. NE bonds receptoR AND TRIGGERS RESPONSE

   1. NE is removed from synapse

Alpha receptor specificity

NE> EPi

beta receptor specificity

B1: NE=Epi

B2: Epi>NE

Cholinergic receptor subtypes

nicotinic receptor

muscarinic

Adrenal cortex

is a true endocrine gland

Adrenal medulla

is a modified sympathetic ganglion

secretes epinephrine into the bloodstream influences B1 receptors in the heart