Chapter 22 Flashcards
What does the Autonomic Nervous System do?
-regulates the involuntary effectors
What are the functions of the ANS?
- heart beat regulation
- smooth muscle contraction
- glandular secretion
- metabolism regulation
- maintain homeostasis
What are the divisions of the ANS?
- sympathetic
- parasympathetic
- enteric
What does the enteric system do?
- intestinal nervous system
- controls visceral effectors in the gut wall
When does the sympathetic nervous system become dominant?
-when fight or flight is activated
What does the Sympathetic NS do?
- produce more energy
- dilate pupils
- increase heart rate and oxygen levels
- divert blood to muscles
- glycogenolysis
- lipolysis
- stimulates the adrenal gland which releases epinephrine which prolongs the effect
When is the parasympathetic nervous system dominant?
-normally
What does the PSNS do?
- conserve and restore body energy
- increase digestive and urinary function
- decreased heart rate and bronchoconstriction
- decrease functions that support activity
What is the general organization of the ANS? Which neurons are myelinated or unmyelinated?
- autonomic nerves (efferent)
- ganglia (cell bodies in the PNS)
- plexuses
- preganglionic neurons are myelinated
- postganlionic neurons are unmyelinated
What is the difference between the structure of the somatic motor pathway and the autonomic nervous system pathway?
- SMP: one efferent nerve; innervates skeletal muscle; uses acetylcholine
- ANSP: two efferent nerves; innervates involuntary activity; uses acetylcholine or norepinephrine
Where are the cell bodies of the preganglionic neurons located? Sympathetic
-lateral horns of the spinal cord
Where are the paravertebral and prevertebral ganglia located? Sympathetic
- paravertebral: around blood vessels; C2 to coccyx
- prevertebral: lie between paravertebral ganglia and target organ
Once the impulse is in the sympathetic chain, where can it go? Sympathetic
- synapse with a sympathetic postganglionic neuron
- go up or down then number 1
- travel to prevertebral ganglia
- travel to adrenal gland
What are splanchnic nerves? Sympathetic
-contribute to innervation of organs
What is unique about the adrenal gland? Sympathetic
- releases hormones into bloodstream
- enhances and prolongs the effects of sympathetic stimulation
What do the postganglionic nerves do? Sympathetic
-send impulses to the effector
Which neurons are long and which are short? Sympathetic
- postganglionic neurons are long
- preganglionic neurons are short
Where are the cell bodies of the preganglionic neurons located? Parasympathetic
-in brainstem and sacral spinal cord
Which cranial nerves carry parasympathetic innervation?
- oculomotor
- facial
- glossopharyngeal
- vagus
Where are the ganglia located? Parasympathetic
-near or embedded in their effectors
What do the postganglionic nerves then do? Parasympathetic
-receive the impulse and send their axons to the effector
Which neurons are long and which are short? Why? Parasympathetic
- preganglionic neurons are long
- postganglionic neurons are short
What is a cholinergic receptor? Releases?
-a receptor that releases acetylcholine
What is an adrenergic receptor? Releases?
-releases norepinephrine
What neurons are cholinergic? Adrenergic?
- Cholinergic: S. preganglionic, S. postganglionic if sweat glands, both PS
- Adrenergic: only S. postganglionic
What do cholinergic receptors bind?
- bind acetylcholine
- neurons release; receptors bind
What types of cholinergic receptors are there? Location?
- nicotinic: in dendrites of postg. neurons; in adrenal medulla
- muscarinic: in PS effectors (involuntary); in plasma membrane of sweat glands of SNS
What types of adrenergic receptors are there? Location? Function?
- Alpha: vasoconstriction of GI tract vessels, pupil dilation, increased sweating
- Beta: vasodilation of skeletal muscle vessels, increased force and rate of contraction of heart, bronchodilation
- on effectors!!
What releases epinephrine? What does it do?
- adrenal gland
- enhances and prolongs sympathetic stimulation (fight or flight)
What are beta blockers? When is it used?
- block norepinephrine binding to beta receptors
- used to lower high blood pressure
What regulates the systems?
-hypothalamus
What is an agonist?
-mimics the neurotransmitter
What is an antagonist?
-blocks the neurotransmitter
