Chapter 15: The Autonomic Nervous System
Describe the actions of somatic motor neurons on skeletal muscles.
-One lower motor neuron from CNS -Cell body of lower motor neuron lies in brainstem or spinal cord, exists in CNS to skeletal muscles -extends from CNS to skeletal muscles -myelinated axons snd thicker in diameter -releases Ach
List the organs served by the sympathetic trunk (chain) ganglia and splanic nerves
-eye -blood vessels and sweat glands of head -salivary glands -heart/its blood vessels -lung -liver and gallbladder -stomach -spleen -adrenal medulla -kidney -pancreas -large/small intestine -rectum -urinary bladder -male and female reproductive organs -skin, and blood vessels
Identify the neurotransmitters and hormones that bind to adrenergic and cholinergic receptors.
Adrenergic -Ne and epinephrine Cholingeric -Ach - Include all sympathetic and parasympathetic preganglionic neuron, all parasympathetic ganglionic neurons, and specific sympathetic ganglionic neurons that innervate sweat glands of the skin
Describe the major responses of the body to stimulation by the sympathetic and parasympathetic divisions of the Autonomic Nervous System.
Autonomic Tone -Balance between parasympathetic and sympathetic activity; regulated by hypothalamus Sympathetic Responses: -During physical or emotional stress; supports vigorous physical activity and rapid ATP production; reduces body functions that store energy - Fight or flight response-Activation of sympathetic nervous system and release of hormones by adrenal medullae causes physiological response Parasympathetic Responses -Rest-and-digest; support body functions that conserve energy during times of rest and recovery; stimulate digestive glands and smooth muscle in GI tract to stimulate digestion and absorption; reduces activities involving physical activity.
Identify the components of an autonomic reflex.
CNIII (oculomtor) -contracts sphincter pupillae muscle of iris to make pupil constrict, -contracts smooth muscle of ciliary body to make lens of eye more spherical (for near vision) CN VII (facial) -increases secretion of lacrimal gland in eye -increases secretions of the submandibular and sublingual salivary glands CN IX (glossopharyngeal) -increases secretion of parotid salivary gland CN X (vagus) -innervates smooth muscle and glands of thoracic and most abdominal organs and cardiac muscle of the heart.
Identify the location of cholinergic and adrenergic neurons.
Cholinergic -Nicotinic- all postganglionic neurons in the ANS, adrenal medulla, and NMJ +excitatory EPSP -Muscarinic- all effectors of parapymathetic target organs -limited to symathetic target organs that have muscarinic receptors +generally excitatory except cardiac muscle pacemaker cells Adrenergic receptors - a1- blood vessels (skin, GI tract, kidneys), arrector pili, uterus, ureters, internal urethral sphincter, dilator puillae msucle of eye +causes contraction of most smooth muscle -a2- CNS (decrease NE release), pancreas (inhibits insulin release), and GI sphincters(cause contraction) -b1- heart (increases heart rate and force of contraction), and kidney (stimulates release of renin to increase blood pressure) -b2- Coronary arteries, liver, skeletal muscle, bronchioles, uterus, and GI tract +causes smooth muscle relation and vasodilation -b3- adipose connective tissue (stimulates lipolysis), and urinary bladder (relaxes detrusor muscle)
Explain the differences in mylenation and length between preganglionic and postganglionic neurons of the autonomic nervous system.
Parasympathetic division -extend from brainstem and sacral region -little branhing (less than 4) -long preganglionic axon -short postganglionic Sympathetic division -extend from thoracic and lumbar region -many branches -short preganglionic -long postganglionic
Describe the different mechanisms the autonomic motor system uses on effectors such as glands, cardiac muscle, and smooth muscle.
Parasympathetic division -local -regulates either one or only a few structures at the same time sympathetic - mass activation-significant neuronal divergence and facilitates the action of many structures simultaneously
Compare the anatomical components of the autonomic nervous system.
Parasympathetic division -maintains homeostasis when at rest ("rest and digest") -conserve energy and replenish nutrients Sympathetic -maintains homeostasis during exercise, energy, or stress ("fight or flight") -release if nutrients from storage (glucose)
Describe preganglionic and postganglionic neurons of the autonomic nervous system.
Preganglionic neurons -have myelinated axons -small in diameter -release Ach to excite the second neuron Postganglionic neurons -unmyelinated axons -smaller in diameter -releases either Ach or NE
Compare the structural and functional differences between the somatic and autonomic parts of the nervous system
Somatic -special senses, skin, and proprioceptors -effector is skeletal muscle fibers -regions of control: cerebrum, thalamus, cerebellum, brainstem, and spinal cord -one lower motor neuron -myelinated -releases Ach -excitation -voluntary movement Autonomic -visceral senses -effector is cardiac muscle, smooth muscle, and glands -regions of control: hypothalamus, brainstem, and spinal cord -2 lower motor neurons: preganglionic and ganglionic -releases ACh or NE -excitiation and inhibition -parasymathetic division and sympathetic division of ganglia -regulates bodily functions such as the heart rate, digestion, respiratory rate, puppillary response, urination, and sexual arousal
Give an example of antagonistic effects of the ANS.
Sympathetic division induces dilation of the pupil while the parasympathetic division induces the pupil to constrict. The sympathetic division speeds up heart rate while the parasympathetic division slows it down.
Explain why the sympathetic division is called the thoracolumbar division.
The cell bodies are located in the lateral horns of the T1-L2 spinal cord segments
Explain the relationship between the hypothalamus and the ANS.
The hypothalamus is the integration and command center It contains nuclei that control visceral functions in both divisions of the ANS and communicates with other CNS regions It is the central brain structure involved in emotions and physiological processes, which are regulated through the ANS
Define autonomic tone.
The parasympathetic and sympathetic division both continuously release neurotransmitters to regulate specific target organs for either sustained stimulus or inhibition
Explain why the sympathetic division produces simultaneous effects throughout the body, in contrast to parasympathetic effects, which typically are localized to specific organs.
mass activation -why they have many branches -activated when adrenal glands are stimulated, causing a release of NE and epinephrine -when stressed,its necessary to coordinate rapid changed in activity with numerous structures at once
