comparison of somatic and autonomic nervous systems

what neurotransmitter do somatic motor neurons release

acetylcholine

what regulates visceral activities of ANS

autonomic motor neurons increase (exciting) or decrease(inhibiting) ongoing activities in their effector tissues (cardiac muscle, smooth muscle, glands)

motor neuron pathway of autonomic nervous system

consist of two motor neurons in series; one following the other. -the first neuron( preganglionic neuron) has its cell body in the CNS; its myelinated axon extends from the CNS to an autonomic ganglion. -the cell body of the second(postganglionic neuron) is also in that same autonomic ganglion; its unmyelinated axons extends directly from the ganglion to the effector(smooth muscle, cardiac muscle, or gland) -some autonomic pathways have different aspects

What neurotransmitter(s) do autonomic motor neurons release

either Acetylcholine or norepinephrine

third division of ANS

enteric nervous system

function of enteric motor neurons

govern contraction of GI tract smooth muscle and secretion of GI tract glands

function of enteric interneurons

integrate information from the sensory neurons and provide input to motor neurons

biggest difference between ANS and SNS

involvement of conscious control

function of enteric sensory neurons

monitor chemical changes within the GI tract as well as the stretching of its walls

dual innervation

most organs receive nerves from both divisions of the ANS

what does voluntary control of movement involve

motor areas of the cerebral cortex that activate somatic motor neurons

Examples of how tissues innervated by the ANS function to some extent even if their nerve supply is damaged

- the heart continues to beat when it is removed for transplantation into another person -smooth muscle in the lining of the GI tract contracts rhythmically on its own - and glands produce some secretions

How are interoceptors different from other sensory signals

- they are not consciously perceived most of the time, although intense activation of interoceptors may produce conscious sensations .

examples of how the ANS operates without conscious control

- you probably cannot voluntarily slow down your heart rate; instead your heart rate is subconsciously regulated -it is for this reason that autonomic responses are the basis for lie detector tests

what structures of the brain provide regulation for ANS reflexes

- centers in the hypothalamus and brain stem

sympathetic nervous system

- promotes "fight or flight" : prepares body for emergency situations -stimulates the organ to increase activity(excitation) -neurons of this system increase heart rate

visceral effectors of ANS

-cardiac muscle, smooth muscle, glands -they are usually associated with viscera(internal organs)

What are some examples of autonomic motor responses

-changes in diameter of the pupils -dilation and constriction of blood vessels -adjustment of the rate and force of the heartbeat

examples of interoceptors

-chemoreceptors that monitor blood CO2 level -mechanoreceptors that detect the degree of stretch in the walls of organs or blood vessels.

enteric nervous system

-consists of millions of neurons in plexuses that extend most of the length of the GI tract -involuntary - neurons of ENS can function autonomously , but can also be regulated by the other divisions of the ANS -contain sensory neurons, interneurons , and motor neurons

somatic nervous system

-consists of somatic motor neurons :innervate skeletal muscles -include sensory and motor neurons -usually operates under voluntary(conscious) control, but not always under voluntary control -can receive sensory input from sensory neurons that convey information for somatic senses (tactile,thermal,pain, and proprioceptive senses; or the special senses( sight, hearing, taste, smell, and equilibrium) -All these sensations normally are consciously perceived

parasympathetic nervous system

-enhances "rest and digest" activities: conserve and restore body energy during times of rest or digesting a meal. -decreases the organ's activity(inhibition) -slow down heart rate

somatic motor neurons

-innervate the skeletal muscles of the body -when a somatic neuron stimulates a skeletal muscle, it contracts; excitation -release only acetylcholine -somatic motor neurons that innervate skeletal muscles involved in posture, balance, breathing, and somatic reflexes (such as the flexor reflex) are involuntarily controlled by integrating centers in the brainstem and spinal cord. -if respiratory motor neurons become inactive, breathing stops. -somatic motor neurons cause the appropriate skeletal muscles of the body to contract in response to sensory information - voluntary control activated by motor areas of the cerebral cortex

what does involuntary control of the somatic neurons involve

-involuntarily controlled by integrating centers in the brainstem and spinal cord somatic motor neurons that innervate skeletal muscles involved in posture, balance, breathing, and somatic reflexes (flexor reflex)

Two examples of perceived visceral sensations in the interoceptors

-pain sensations from damaged viscera and angina pectoris (chest pain) from inadequate blood flow to the heart -signals from the somatic senses and special senses, acting via the limbic system, also influence responses of autonomic motor neurons . Ex: seeing a bike about to hit you , hearing squealing brakes of a nearby car, or being grabbed by an attacker would all increase the rate and force of your heartbeat

Autonomic nervous system

-regulates cardiac muscle, smooth muscle, and glands -consists of autonomic motor neurons that regulate visceral activities by either increasing (exciting) or decreasing(inhibiting) ongoing activities in their effector tissues(cardiac muscle, smooth muscle, and glands) -receive sensory input from sensory neurons associated with interoceptors -usually operates without conscious control , though centers in the hypothalamus and brain stem provide regulation for ANS reflexes -once thought to be self governing -often function to a certain extent even if their nerve supply is damaged -has two main divisions ; each division contains 2 motor neurons -has a third division

What are the 2 divisions of the motor division of the PNS

-somatic nervous system (SNS) -autonomic nervous system (ANS)

Two main divisions of the ANS

-sympathetic nervous system -parasympathetic nervous system

ganglion

a collection of neuronal cell bodies in the PNS

Biofeedback

a technique in which an individual is provided with information regarding an autonomic responses such as heart rate, blood pressure, or skin temperature. various electronic monitoring devices provide visual or auditory signals about the autonomic responses . by concentrating on positive thoughts, individuals learn to alter autonomic responses. For example, biofeedback has been used to decrease heart rate and blood pressure and increase skin temperature in order to decrease the severity of migraine headaches

what do chromaffin cells secrete

neurotransmitters epinephrine and norepinephrine (NE)

how does the ANS receive sensory input

sensory input from sensory neurons associated with interoceptors.

where does the somatic nervous system receive sensory input from

sensory neurons that convey information for somatic senses(tactile, thermal,pain, and proprioceptive sensations) -special senses(sight, hearing, taste, smell, and equilibrium)

interoceptors

sensory receptors located in blood vessels, visceral organs, muscles, and the nervous system that monitors conditions in the internal environment

motor neuron pathway of somatic nervous system

the axon of a single, myelinated somatic motor neuron extends from the CNS all the way to the skeletal muscle fibers in its motor neuron

alternative motor pathways in some autonomic pathways

the first motor neuron extends to specialized cells called chromaffin cells in the adrenal medullae (inner portion of the adrenal glands) rather than autonomic ganglion