ch14

autonomic nervous system

regulates internal organs through homeostasis and endocrine system

• directed by hypothalamus

• two neurons from CNS to effector

sympathetic system

associated with fight-or-flight response, usage of energy

• mobilize body during activity

• release norepinephrine

• physical activity or emotion

parasympathetic system

associated with rest and digestion, conservation of energy

• maintenance functions

• released ach

autonomic reflex arc

1. cell body (ganglion)

2. preganglionic myelinated cell

3. release ach

4. postganglionic non myelinated cell

5. norepinephrine/ach

6. target organ

7. stimulatory

preganglionic neuron

cell body located n CNS, myelinated

postganglionic neuron

cell body located outside of CNS

cholinergic

receptors that bind to ach

nicotinic receptor

bind to ach, stimulatory effect on the target cell

muscarinic receptor

bind to ach, either inhibitory/excitatory depending on receptor type of target organ

adrenergic

divided into alpha (a1, a2) and beta (b1, b2, b3) receptors

• effect depends on combination of receptors, availability, and dominance

autonomic tone

each system favors either sympathetic or parasympathetic resting state

• balance of homeostasis attributed to antagonistic relationship

eye

P: constricts pupil

S: dilates pupil

glands

P: stimulates secretion
S: restricts secretion

arrector pili

P: n/a
S: stimulates contraction (goose bumps)

heart

P: decrease rate
S: increase rate

urinary bladder

P: contracts wall (promotes urination)
S: relaxes wall (inhibits urination)

lungs

P: constricts bronchioles
S: dilates bronchioles

digestive tract organs

P: increase motility to move food
S: decrease activity

liver

P: increase glucose uptake (decrease glucose levels)
S: release glucose to blood (increase levels)

blood vessels

P: n/a
S: constricts, increase pressure

medial forebrain bundle

frontal, occipital, spinal cord

dorsal longitudinal fasciculus

midbrain, pons, medulla oblongata