Exam 1 – Dr. Archer Flashcards
What does the autonomic nervous system contain?
Central and peripheral nervous system
What is the ANS?
Involuntary motor system for internal organs, heart, blood vessels, and secretory glands
What do motor neurons in the ANS do?
Connect the CNS to the target organ
Where are the higher centers located in the CNS?
Hypothalamus
Midbrain
Pons
Medulla
What is the hypothalamus?
The primary integrating center of the ANS
What does ANS control operate through?
CNS
Visceral reflexes
How many chains are there in the ANS?
2
Where is the 1st neuron?
CNS
Where is the 2nd neuron?
Within a ganglion (outside of CNS)
Where is the cell body of the preganglionic axon located?
Brain stem or spinal cord
Describe the axon of the visceral motor neuron
Thinly myelinated
Projects to an autonomic ganglia
Where is the cell body of the postganglionic neuron located?
Within the autonomic ganglia with an unmyelinated axon projecting to visual effector cell
What is the ANS divided into?
Sympathetic and parasympathetic
What are similarities between the sympathetic and parasympathetic systems?
Both are efferent systems
Both involve regulation of the “internal” environment generally outside of our conscious control
Both involve 2 neurons that synapse in a peripheral ganglion
Innervate glands, smooth muscle, cardiac muscle
What is the location of the sympathetic nervous system?
Thoraco-lumbar
Where are the preganglionic neuron cell bodies housed?
The lateral horn of the T1-L2 regions of the spinal cord
Where are the right and left sympathetic trunks located?
Immediately lateral to the vertebral column
What is the sympathetic trunk composed of?
Bundles of axon
Ganglia
Short pre-ganglionic fibers and long post-ganglionic fibers
What is does the sympathetic trunk ganglia house?
Sympathetic ganglionic neuron cell bodies
What is the adrenal medulla innervated by?
The sympathetic nervous system
What is the adrenal medulla considered?
A modified sympathetic ganglion
What does the stimulation of the adrenal medulla cause?
The release of norepinephrine and epinephrine
What does the adrenal medulla reinforce?
Activity of the sympathetic nervous system
What is the parasympathetic nervous system also known as?
Carniosacral division
Where are the visceral motor neurons of the parasympathetic nervous system located?
In discrete brain stem nuclei and in sacral segments 2-4
What do the oculomotor nerve fibers go to?
Pupillary sphincters and ciliary muscle
What do the facial nerve fibers go to?
Nasal, lacrimal, and submandibular gland
What do the glossopharyngeal nerve fibers go to?
Parotid gland
What do the vagus nerve motor inputs go to?
Visceral organs
What do the sacral segment fibers go to?
Descending colon, rectum, bladder, and genitalia
What is the vagus nerve the major source of?
Parasympathetic stimulation for the thoracic and most abdominal organs
What are the ganglionic neurons in the parasympathetic division?
Terminal ganglia
Intramural ganglia
Where are terminal ganglia located?
Close to the target organ
Where are intramural ganglia located?
Within the wall of the target organ
What are autonomic reflexes similar to?
Spinal reflexes
What do autonomic reflexes do?
Help maintain homeostasis through the involuntary activity of autonomic reflexes or visceral reflexes
What do autonomic reflexes consist of?
Smooth muscle contractions
Cardiac muscle contractions
Secretion by glands that are mediated by autonomic reflex arcs in response to a specific stimulus
What is Autonomic function influenced by?
The cerebrum, hypothalamus, brainstem, and spinal cord
What does sensory processing in the thalamus directly affect?
The hypothalamus
What does the hypothalamus contain?
Nuclei that control visceral functions in both divisions of the ANS
What does the hypothalamus communicate with?
Other CNS regions, including the cerebral cortex, thalamus, brain stem, cerebellum, and spinal cord
What do the brainstem nuclei mediate?
Major ANS reflex/control centers:
Arterial blood pressure
Heart rate
Respiratory rate
How are certain process (such as defecation and urination) processed and controlled?
At the level of the spinal cord without the involvement of the brain
What can consciously inhibit reflex activities like urination?
Cerebrum
What do ANS neurotransmitter do?
Stimulate activity in some tissues while inhibiting activity in others
What do responses from neurotransmitters depend on?
Specialization of the tissue cells, containing one or more membrane receptors
What are the 2 main neurotransmitters?
Acetylcholine
Norepinephrine
What receptor utilizes acetylcholine?
Cholinergic receptors
What are the 2 types of cholinergic receptors?
Nicotinic receptors
Muscarinic receptors
Where are nicotinic receptors?
On the cell bodies in all autonomic ganglia
Where is Ach released from that binds with nicotinic receptors?
All sympathetic and parasympathetic preganglionic fibers
Where are muscarinic receptors found?
On effector cell membranes (smooth muscle, cardiac muscle, and glands)
Where is Ach released from that binds with muscarinic receptors?
Parasympathetic postganglionic receptors
After Ach interacts with its receptors, what happens?
Ach is split by acetylcholinesterase
What do adrenergic receptors respond to?
Epinephrine (Epi) and norepinephrine (NE)
What are the different types of adrenergic receptors?
α, β1, β2
What does NE excite?
α receptors
What does Epi excite?
Both types of receptors (α and β) with equal affinities
How are adrenergic receptors distributed?
Distinctly among the effector organs and can be excitatory or inhibitory
Where are α receptors located?
Blood vessels
Eye
Where are β1 receptors located?
Heart
Where are β2 receptors located?
Bronchioles
Blood vessels to the heart and skeletal muscles
Smooth muscle walls of the digestive and urinary systems
What is the sympathetic nervous system responsible for?
Fight or flight
Preparing the body for emergencies
What are examples of mass sympathetic discharge from the sympathetic nervous system?
Increase in arterial pressure Increase in heart rate and contractility Increase in blood flow to muscles Increase in blood glucose Increase in metabolic rate Increase in muscle strength Increase in mental activity
What does the sympathetic nervous system prepare the body for?
Vigorous activity needed to deal with a life-threatening situation
What does the activation of beta 1 cause?
An increase in heart rate and contractility
What does the activation of beta 2 cause?
Bronchial dilation and dilation of blood vessels in skeletal muscles
What are the functions of alpha receptors?
Vasoconstriction Iris dilation Intestinal relation Intestinal sphincter contraction Pilomotor contraction Bladder sphincter contraction Inhibits neurotransmitter release
What are the function of beta receptors?
Vasodilation Cardioacceleration Increased myocardial strength Intestinal relaxation Uterus relaxation Bronchodilation Calorigenesis Glycogenolysis Lipolysis Bladder wall relaxation Thermogenesis
What does the adrenal medulla do?
Release of Epi and NE
What are the percentages of Epi and NE released by the adrenal medulla?
80% Epi
20% NE
What is the parasympathetic nervous system responsible for?
Rest and digest
Conserves energy and replenishes nutrient stores
What does the parasympathetic nervous system promote?
Digestion of food
Storage of energy
Elimination of wastes
Homeostasis
What does the parasympathetic nervous system usually cause?
Specific localized response
Is there mass discharge with the parasympathetic nervous system?
No
What are the muscarinic receptor effects in cardiac muscle?
Decreases heart rate and strength of contraction
What are the muscarinic receptor effects in the digestive system?
Increase digestive activity including secretions and peristalsis
What are the muscarinic receptor effects in digestion?
Increases flow of blood to liver, pancreas, and digestive organs by vasodilation of appropriate vessels
What are the muscarinic receptor effects in the eye?
Causes constriction of Iris
