Chapter 16: Autonomic Nervous System
Identify the divisions of the Autonomic Nervous System (ANS)
- Enteric Nervous System - Sympathetic - Parasympathetic
Which are parasympathetic effects on the reproductive system?
- Penile or clitoral engorgement - Stimulation of glandular secretion in the male reproductive tract
Name the locations of the nicotinic receptors
- Postganglionic neurons in the autonomic ganglia - Skeletal muscle cells
Which are sympathetic effects on the urinary system?
- Reduced urine output by the kidneys - Contraction of the internal urethral sphincter
Which are parasympathetic effects on the urinary system?
- Relaxation of the internal urethral sphincter - Contraction of the urinary bladder wall
The peripheral nervous system (PNS) is composed of what types of neurons?
- Sensory neurons - Motor neurons
Which are sympathetic effects on the reproductive system?
- Smooth muscle role in orgasm - Labor contractions of the uterus
Identify the nerves that transmit sympathetic information
- Spinal nerves T1 - T12 - Spinal nerves L1 - L2
Which are associated with the parasympathetic division of the autonomic nervous system?
- Urination - Digestion - Defecation
Describe a nerve plexus
A complex, interconnected neural network formed by neurons of the sympathetic and parasympathetic divisions
What is a preganglionic neuron?
A neuron that extends from the spinal cord or brainstem to a ganglion
Which nervous system division is usually under involuntary control?
Autonomic
What is the effect of parasympathetic stimulation on the heart?
Decreases heart rate
Name the effector site for the enteric nervous system (ENS)
Digestive tract
Identify the location of muscarinic receptors
Effector cells of postganglionic neurons
True or false: All neurotransmitters result in excitatory stimulation when they bind to target receptors
False: Depending on the cell type, the response is excitatory or inhibitory.
True or False: Parasympathetic nerve signals will pass via the spinal nerves to reach the neck.
False: Parasympathetic nerve signals to the neck travel with cranial nerves, not spinal nerves.
True or false: It is physiologically impossible for a target tissue to be stimulated by both the sympathetic and parasympathetic nervous systems
False: Tissues do respond differently to simulation from these systems. However, the results are not always opposite
What is the effect of parasympathetic stimulation of muscarinic receptors in the stomach?
Increases muscle contraction
Name the peripheral nervous system component responsible for the transmission of action potentials from the CNS to the periphery
Motor neurons
Which part of the nervous system carries information to and from the CNS and various regions of the body?
Peripheral nervous system
Name the division of the ANS containing preganglionic neurons synapses with many postganglionic neurons and which typically has greater stimulatory effects
Sympathetic
What convention is used to name autonomic nerve plexuses?
They are named for the associated organs.
Describe a postganglionic neuron.
They are unmyelinated and extend from the autonomic ganglion to the target cells
Agonists bind to specific receptors and _____ them, whereas antagonists bind to specific receptors and _____ them.
activate, inactivate
Drugs that bind to specific receptors and activate them are called ______, whereas drugs that prevent activation are called ______
agonists, antagonists
The combined effects of the parasympathetic and sympathetic divisions on a target
are not always opposite in their effects
Homeostasis is maintained primarily by the
autonomic nervous system
Autonomic nerve plexuses found supplying the heart would be called
cardiac plexuses
Name the location of the receptors for acetylcholine and norepinephrine
cell membrane
If a sympathetic nerve secretes acetylcholine, the neuron is called a(n) _____ neuron
cholinergic
The division of the autonomic nervous system that is only associated with the walls of the digestive tract is the
enteric nervous system
Adrenal medulla cells are divided into two groups, those that secrete ___________ and those that secrete __________
epinephrine, norepinephrine
The sympathetic division shunts blood and nutrients to structures that are active and away from non-essential organs. This is sometimes called the ______
fight-or-flight response
The adrenal medulla is the ______ portion of the adrenal gland
inner
The primary function of the ANS is to ______
maintain homeostasis
Action potentials are carried from the central nervous system (CNS) to the periphery by ______ neurons, while ______ neurons carry action potentials from the periphery to the CNS
motor, sensory
Effector cells that respond to acetycholine released from postganglionic neurons possess ______ receptors on their cell membranes.
muscarinic
Cholinergic receptors located in the membrane of all postganglionic neurons in the autonomic ganglia and in the membranes of skeletal muscle cells are
nicotinic
A sudden increase in blood pressure initiates a ______ reflex that ______ the cardiac muscle cells
parasympathetic, inhibits
The rate of smooth muscle contraction in the digestive organs is increased when the neurotransmitters of the ______ division of the autonomic nervous system bind to _____ receptors.
parasympathetic, muscarinic
Parasympathetic nerve signals will pass via the ______ to reach the large intestine
pelvic splanchnic nerves
A complex, interconnected neural network formed by neurons of the sympathetic and parasympathetic division is called a nerve
plexus
Receptors for acetylcholine and norepinephrine receptors are located in the
postsynaptic membrane
The autonomic nervous system uses _____ to help maintain homeostasis in the absence of CNS input
reflexes
The pelvic splanchnic nerves are formed by preganglionic parasympathetic fibers from the ______ region of the spinal cord
sacral
For the somatic motor nervous system, _________ motor neurons carry impulses from the CNS to effectors (skeletal muscles). In the autonomic nervous system, _____________ (number) autonomic neurons carry signals from central nervous system to the effectors
somatic, two
Depending on the body location, the parasympathetic division of autonomic nervous system is
stimulatory or inhibitory
A sudden decrease in blood pressure initiates a _____ reflex that ______ the heart.
sympathetic/excites
How many neurons form the autonomic nervous system pathways?
two