Ch. 16 Flashcards
The autonomic nervous system (ANS) maintains homeostasis of the body by regulating many involuntary activities including…
Heart rate, breathing rate, body temp, digestive processes and urinary functions
The somatic motor system regulates activites of the skeletal muscle and the ANS regulates the activity of all other effectors such as..
Smooth muscle, cardiac muscle and glands
The ANS is divided into what 3 divisions?
Sympathetic division
Parasympathetic division
Enteric nervous system
The enteric nervous system consists of
nervous tissue of the digestive tract
Sympathetic divison is often referred to as _______ because____________?
Fight or flight
bc it has more influence on effectors inder conditions of increased physical activity or stress
Maximum expendure of energy / best use possible
The parasympathetic division is often referred to as________ because _____________?
Rest and digest divison
Has more influence under conditons of rest
Motor neurons that innervate skeletal muscles are called Somatic motor neurons. Motor neurons that innervate smooth muscle, cardiac muscle and glands are called
autonomic motor neurons and are part of ANS
The ANS has 2 neurons in a series extending between CSN and the innervated organs, What are the 2 neurons called?
Preganglionic neuron and Postganglionic neuron
The preganglionic neuron cell body is located where?
In the CNS within either brainstem or lateral gray horn and axons extend to autonomic ganglion outside of the CNS
The postganglion neuron synapses with preganglion neuron where?
Autonomic ganglia where the postganglion neuroncell bodies are located the axons exend to teh effector organs and synapse with their target tissues
The postganglion neuron synapses with preganglion neuron where?
Autonomic ganglia where the postganglion neuroncell bodies are located the axons exend to teh effector organs and synapse with their target tissues
The axons of all somatic motor neurons are myelinated. What are the axons of ANS?
Preganglion nuerons are myelinated
Postganglion neurons are unmyelinated
Many movements of somaic nervous system are volunatary, ANS is?
Involuntarily controlled
The effect on somaic motor neurons on skeletal muscles are always excitatory, the effect on autonomic motor neurons is?
Either excitatiry or inhibitory
The major neurotransmitter in somatic motor system is acetylcholine (ACH) the major neurotransmitter in ANS is?
ACH
Epinephrine (E)
Norepinephrine (NE)
Somatic always uses ACH what does the autonomic system use?
Preganglionic neuron uses ACH
Postganglionic neuron uses either ACH or norephinephrine
Sympathetic divison
Aka Thoracolumnar divison
Where are cell bodies located and why is it called Thoracolumnar divison?
Cell bodies of sympathetic preganglion neurons are in the lateral horns of spinal cord gray matter between T1 and L2
What are the 2 types of sympathic ganglia?
Sympathetic chain ganglia and collateral ganglia
Sympathetic chain ganlgia
Aka Paravertebral ganglia
Located along left and right sides of vertebral column. Connected to each other forming a chain
As a result of fusion during fetal development there are usually how many pairs of ganglia …
3 pair’s of cervical ganglia
11 pairs of thoracic ganglia
4 pairs of lumbar ganglia
4 pairs of sacral ganglia
Collateral ganglia
Aka prevertebral ganglia
unpairs ganglia located in abdominopelivc cavity.
*Anterior to vertebral column
What are the 4 potential pathways of axons that exit the sympathetic chain ganglion?
- Spinal nerves
- Sympathetic nerves
- Splanchnic
- Innervation to the adrenal gland
What is the pathway of axons that exit sympathetic chain ganglia to spinal nerves?
- Exit lateral gray horn and out ventral root through white ramus communicans
- Synpase with postganglionic neuron in sympathic chain ganglion
*They can synapse at same leve or inferiorly or superiorly
- Axons of postganglion neurons pass through the gray ramus communicans and reenter a spinal nerve
- Project through spinal nerve to skin and blood vessels of skeletal muscles
What is the pathway of axons that exit sympathetic chain ganglia to Sympathetic nerves?
- Exit lateral gray horn and out ventral root through white ramus communicans
- Synpase with postganglionic neuron in sympathic chain ganglion
*They can synapse at same leve or inferiorly or superiorly
- Postganglionic axons leaving the sympathetic chain ganglion form sympathetic nerves, which supply organs in thoracic cavity, such as heart
What is the pathway of axons that exit sympathetic chain ganglia to Splanchnic nerves?
- Exit lateral gray horn and out ventral root through white ramus communicans, enter sympathetic chain ganglia and, without synapsing exit at same or different level to form splanchnic nerves.
- They enter the collateral ganglion where they synpase with postganglionic neurons
- Then extend o the effectors of abdominopelvic cavity
Splanchnic nerves are composed of __________sympathetic nerves are composed of __________
Preganglionic axons
Postganglionic axons
What is the pathway of axons that exit sympathetic chain ganglia to innervation of adrenal gland?
The innervation of adrenal gland is through a splanchnic nerve.
- Exit lateral gray horn and out ventral root through white ramus communicans pass through sympathetic chain ganglion and collateral ganglion
- Synpase with cells in the medulla of adrenal gland
- Cause release of either epinephrine or norepinephrine which circulate in blood and affect all tissues having receptors to which they can bind.
*General response is to prepare an individual for physical activity
Adrenal medulla
inner portion of the adrenal gland and consists of specialized cells dervied from neural crest cells during embryonic development
*Neural crest cells are the same cells that give rise to the postganglionic cells of ANS
Adrenal medullary cells are
Round and have no axons or dendrites and are divided into 2 groups
80% secrete epinephrine aka adrenaline
20% secrete norepinehrin aka noradrenaline
Parasympathetic division
aka craniosacral division
Cell bodies are located in either within cranial nerve nuclei in brainstem or within lateral parts of gray matter in sacral region of spinal cord from S2-S4
Axons from the parasympathetic preganglionic neurons from the brain are cranial nerves?
III, VII, IX, X
The axons associated with the sacral region are?
Pelvic splanchnic nerves
The axons of parasympathetic preganglionic neurons course through cranial nerves or pelvic splanchnic nerves to
termianl gangla where they synapse with postganglionic neurons then to the effectors
*The terminal ganglia are either near or embedded within the walls of the organs innervated by parasympathetic organs
Autonomic nerve plexuses
complex interconnected neural networks formed by neurons of the sympathetic and parasympathetic diviisons
Axons of sensory neurons also contribute
Autonomic nerve plexuses are typically named according to the organs they supply or blood vessels along which they are found
What are the major ways sympathetic postganglion axons reach effectors?
- Spinal nerves
- Head and neck nerve plexuses
- Thoracic nerve plexuses
- Abdominopelvic nerve plexuses
Cardiac plexus
Regulating the heart
Pulmonary plexus
regulating the lungs
What are the 4 abdominopelvic nerve plexus?
Celiac plesus - innervates diaphram, stomach, spleen, liver, gallbladder, adrenal glands, kidneys, testes and ovaries
Superior mesenteric plexus - innervates pancreas, small intestine, ascending colon and transverse colon
Inferior mesenteric plexus - innervates transverse colon to the rectum
Superior and inferior hypogastric plexus innervates descending colon to recum, urinary bladder and reproductive organs in pelvis
The major means by which parasympathetic postganglionic axons reach effectors are?
Cranial nerves innervating head and neck
The vagus nerve and thoracic nerve plexus
Abdominal nerve plexus
Pelvic splanchnic nerves and pelvic nerve plexus
What are the 3 pairs of cranial nerves that have parasympathetic preganglionic axons that extend to terminal ganglia in the head and postganglionic neurons innervate the nearby structures?
- Oculomotor nerve through ciliary ganglion, innervates ciliary muscles and iris of eye
- Facial nerve through pterygopalatine ganglion innervates lacrimal gland the mucosal glands of nasal cavity and palate. Facial nerve through the submandibular ganglion, also innervates the submandibular and sublingual salivary glands
- Glossopharyngeal nerve, through otic ganglion, innervates the parotid salivary gland
Where are the sensory neurons in autonomic nerve plexuses located?
Cell bodies aare found in dorsal root ganglia of spinal nerves and in the cranial nerve sensory ganglia
The enteric nervous system consists of nerve plexuses with the?
Wall of digestive tract
The enteric nervous system plexuses have contributions from what 3 sources?
- Sensory neurons that connect digestive tract to CNS
- ANS motor neurons that connect the CNS to the digestive tract
- Enteric neurons, which are confined to the enteric plexuses
What are the 3 major types of enteric neurons
- Enteric sensory neurons - detect changes in chemical composition of the contents of digestive tract or dectect stretch of digestive tract
- Enteric motor neurons - stimulate or inhibit smooth muscle contraction and gland secretion
- Enteric interneurons - connect enteric sensory and motor neurons to each other
Dual innervation
The ANS innervates most organs by both sympathetic and parasympathetic neurons
Examples of both: Gastrointestincal tract, heart, urinary bladder, and reproductive tract
What are the typical responses produced by the sympathetic division during excersice ?
- Increased heart rate and force of contraction increase blood pressure and movement of blood
- Vasodialation of blood vessels in skeletal and cardiac muscle - O2 and nutrients are used and waste products are produced
- Vasocontriction occurs in blood vessels of tissues not involved in excersice
- Dilation of air passageways
- Increased breakdown of stored energy sources (glycogen to glucose)
- Body temp increases generating heat
- Activities of non essential organs decrease. Ex. digesting food decreases
Increased activity of parasympathetic division during rest includes?
- Regulates digestion by stimulating secretion of glands, promoting mixing of food and moving through digestive tract
- Controls defecation and urination
- Lowers heart rate and lowers blood pressure
- Contricts air passageways
Sympathetic and parasympathetic neurons secrete one of 2 neurotransmitters?
Acetylcholine or norepineohrine
If a neuron secretes acetlychloine it is called?
Cholinergic neuron
*All preganglionic neurons of the sympathetic and parasympathetic divisions are cholinergic
*All postganglionic neurons of the parasympathetic divisons are also cholinergic
*A few postganglionic neurons that innervate thermoregulatory swea glands are cholinergic
If a neuron secretes norepinephrine it is called?
adrenergic neuron
*Most all postganglionic neurons fo the sympathetic division are adrenergic
What are the substances other than regular neurotransmitters that have been extracted from ANS neurons?
Nitric oxide, fatty acids, monoamines
Agonist
bind to specific receptors and activate them
Antagonists
bind to specific receptors and prevent them from being activated
Cholinergic receptors are classified as?
- Nicotinic receptors
- Muscarinic receptors
Adrenergic receptors
to which norepinephrine or epinephrine binds.
Located in plasma membrane of effectors innervated by sympathetic division
Adrenergic receptors are subdivided into what 2 categories?
Alpha (a) receptors
Beta (b) receptors
Adrenergic receptors can be stimulated in what 2 ways?
- By the nervous system
- by epinephrine and norepinephrine released from adrenal gland
Auonomic reflexes involve
Adjustments to cardiac muscle, smooth muscle, and glandular tissues in response to stimuli
Involved sensory receptors, interneurons, motor neurons and effector cells
Barorecptors
(stretch receptors) in the walls of large arteries near heart detect changes in blood pressure
The hypothalamus is in overall control of ANS. for the most part, Stimulation of the posterior hypothalamus produces _________ where stimulation of the anterior hypothalamus produces __________ responses
Sympthetic responses
Parasymapthetic responses
Local reflex of enteric nervous system
does not involve CNS but produces an involuntary unconscious, stereotypical response to a stimulus
Hirschsprung disease
caused by ineffective parasympathetic stimulation of the colon
Visceral effectors do not need _____ to function
ANS - only to adjust activity to chaning needs
Autonomic tone
normal background rate of activity that represents a balance of the 2 systems according to the bodys changing needs
Parasympathetic tone
Maintains smooth muscle tone in intestines and holds resting HR down to 70-80BPM
Sympathetic tone
Keeps most BV partially constricted to maintain BP. Excites the heart but inhibits digestive and urinary functions (Parasympathetic is opposite)
What is the big parasympathetic nerve/reflex?
Vagus nerve - lowers heart rate
What is the sympathetic reflex/nerve?
Cardiac accelerator - increases heart rate
What are examples of parasympthatetic nerves?
Things that have to do with
Gastric and intestinal
Defecation/urination
Swallowing
Coughing
baroreceptor
What are examples of sympthatetic nerves?
Cardioacceleratory
Vasomotor