Motor division of the peripheral nervous system

what is the alternative name for the visceral motor division of the peripheral nervous system?

autonomic system

which branch of the autonomic system is dominant most of the time

parasympathetic branch

which branch of the autonomic system is dominant in stressful situations and exercise

sympathetic branch

what is the sympathetic response of the pupil

it dilates via binding to alpha adrenergic receptors

what is the sympathetic response of the salivary glands

secretion of mucus and enzymes via binding to alpha and beta 2 adrenergic receptors

what is the sympathetic response of the heart

increased heart rate (norepinephrine binds to beta receptors on the heart) and force of ventricle contraction (norepinephrine binds to beta receptors on the heart)

what is the sympathetic response of the arterioles and veins

vasodilation of coronary vessels and skeletal muscles (epinephrine binds to beta receptors on skeletal muscles/coronary vessels) and vasoconstriction of peripheral vessels (epinephrine binds to alpha receptors on peripheral vessels)

what is the sympathetic response of the lungs

bronchioles dilate and increased breath rate via hormonal epinephrine binding to beta 2 adrenergic receptors

what is the sympathetic response of the digestive tract

decreases motility and secretion/slowing of peristalsis in muscles in the digestive tract (epinephrine binds to alpha receptors on smooth muscle)

what is the sympathetic response of the exocrine pancreas

decreases enzyme secretion via binding to alpha adrenergic receptors

what is the sympathetic response of the endocrine pancreas

inhibits insulin secretion via binding to alpha adrenergic receptors

what is the sympathetic response of the adrenal medulla

secretes catecholamines

what is the sympathetic response of the kidneys

increases renin secretion via binding to beta 1 adrenergic receptors

what is the sympathetic response of the urinary bladder

urinary retention via binding to alpha and beta 2 adrenergic receptors

what is the sympathetic response of adipose tissue

fat breakdown via binding to beta adrenergic receptors

what is the sympathetic response of sweat glands

localized sweating via binding to alpha adrenergic receptors

what is the sympathetic response of male and sex organs

ejaculation for males via binding to alpha adrenergic receptors

what is the sympathetic response of the uterus

depends on stage of the cycle but is done via binding to alpha and beta 2 adrenergic receptors

what is the sympathetic response of lymphoid tissue

generally inhibitory via binding to alpha and beta 2 adrenergic receptors

what receptors are all parasympathetic responses mediated by

muscarinic receptors

what is the parasympathetic response of the pupil

constriction

what is the parasympathetic response of the salivary glands

watery secretion

what is the parasympathetic response of the heart

decrease in heart rate

what is the parasympathetic response of the lungs

bronchioles constrict

what is the parasympathetic response of the digestive tract

increased motility and secretion

what is the parasympathetic response of the exocrine pancreas

increased enzyme secretion

what is the parasympathetic response of the endocrine pancreas

stimulates insulin secretion

what is the parasympathetic response of the urinary bladder

release of urine

what is the parasympathetic response of the male and female sex organs

erection

what is the parasympathetic response of the uterus

depends on the stage of the cycle

as the body prepares to fight/flee or starts exercising, what happens?

• increased heart rate

• increased force of ventricular contraction

• vasodilation of coronary blood vessels and skeletal muscle blood vessels

• vasoconstriction of peripheral blood vessels

• increased release of glucose from the liver and adipose cells (epinephrine)

• smooth muscle relaxation of the gastrointestinal tract

• blood is diverted from the gastrointestinal tract to skeletal muscles

what is massive sympathetic discharge

a process mediated through the hypothalamus which is a total body response to crisis (most sympathetic responses are not the full response of a fight or flight reflex)

what are the regulated variables

• temperature

• pH

• ions (calcium, potassium, sodium, chloride, HCO3-)

how does the process of homeostasis work

what the monitored regulated variables within the body move out of proper range, chemical and electrical messages move through a series of steps to signal an effector tissue to perform an action which brings the regulated variable(s) back into range through a system called the physiologic control system

general steps of the physiologic control system

1. stimulus

2. sensor/integrating center

3. efferent pathway

4. effector

5. tissue response

6. systemic response

7. negative feedback

physiologic control system steps for low calcium in the blood

1. low calcium in the blood

2. parathyroid cell detects this

3. parathyroid hormone is released by the parathyroid cell

4. parathyroid hormone travels through the blood and binds to bone and kidneys

5. parathyroid hormone triggers osteoclasts in bone to release calcium from matrix, increased reabsorption of calcium from renal tubular fluid, and the production of calcitrol from the kidneys which leads to an increase in absorption of calcium from the small intestine

6. bone resorption, kidney resorption, and intestinal resorption all increase calcium levels in the blood

7. the parathyroid cell detects this increase in calcium levels in the blood and stops producing parathyroid hormone

physiologic control system for bowel movements

1. pain from gas or feces in large intestine

2. stretch of large intestine activates nociceptors which generate action potentials

3. action potentials travel via visceral sensory nerves

4. action potentials travel through ascending pathways up the spinal cord

5. action potentials reach the postcentral gyrus (primary sensory cortex)

6. pain is perceived

7. action potentials travel to medulla oblongata where parasympathetic system is activated

8. action potentials are sent through visceral motor nerves

9. smooth muscle contraction of the large intestine

10. response (expel gas or feces)

where does sensory information from somatic and visceral receptors go

medulla oblongata, pons, and hypothalamus of the brainstem (parts of the brain that regulate blood pressure, temperature, and water balance)

what does the motor output from the hypothalamus and other parts of the brainstem create

creates autonomic responses, endocrine responses, and behavioral response

what can sensory information integrated in the cerebral cortex and limbic system create

it can create emotions that influence autonomic output such as blushing, fainting at the sight of a hypodermic needle, and butterflies in the stomach

what kind of control are most internal organs under

antagonistic control

what does it mean if something is under antagonistic control

• one autonomic branch of the organ is excitatory and the other branch is inhibitory

• for example, heart rate is regulated by adjusting the relative proportion of sympathetic and parasympathetic control

• sympathetic innervation to the heart increases heart rate and parasympathetic stimulation decreases heart rate

what are the exceptions to antagonistic control

• smooth muscle in most blood vessels and sweat glands are innervated only by the sympathetic branch

• autonomic branches can work cooperatively

• for example, blood flow for penile erection is controlled by the parasympathetic branch, muscle contraction for sperm ejaculation is caused by the sympathetic branch

what two neurons do all autonomic pathways consist of

• a preganglionic neuron (first neuron) which originates in the central nervous system and terminates at an autonomic ganglion outside the CNS

• the preganglionic neuron then synapses with a postganglionic neuron (second neuron) in the pathway

what are the anatomical differences between the sympathetic and parasympathetic branches

• where the pathways originate in the central nervous system

• the location of the autonomic ganglia

where do most sympathetic pathways originate

the thoracic and lumbar regions of the spinal cord

where are sympathetic ganglia found

they are found in a chain that runs close to the spinal column or along the descending aorta

how are sympathetic pathways characterized

they are characterized by short preganglionic neurons and long postganglionic neurons

where do most parasympathetic pathways originate

they originate in the brain stem and their axons leave the brain as cranial nerves

where do a minority of parasympathetic pathways originate

other parasympathetic pathways originate in the sacral region

where are parasympathetic ganglia located

they are located on or near their target organs

how are parasympathetic pathways characterized

they are characterized by preganglionic neurons with long axons and postganglionic neurons with short axons

where parasympathetic innervation primarily go

it goes primarily to the head, neck, and internal organs

what is the major parasympathetic tract

the vagus nerve (CN X) which contains about 75% of all parasympathetic fibers

what neurons/fibers does vagus nerve carry

it carries sensory neurons from the internal organs and parasympathetic fibers to the internal organs

what is divergence regarding nerve signals

• on average, one preganglionic neuron entering a ganglion synapses with eight or nine postganglionic neurons

• each postganglionic neuron may innervate a different target tissue

• therefore, a single signal from the CNS can affect a large number of target cells simultaneously

what do all autonomic preganglionic neurons release

they all release acetylcholine onto cholinergic nicotinic receptors

what do most postganglionic sympathetic neurons secrete

most secrete norepinephrine onto adrenergic receptors

what do most postganglionic parasympathetic neurons secrete

most secrete acetylcholine onto cholinergic muscarinic receptors

what are the neurocrines

neurotransmitters, neuromodulators, and neurohormones

what are the seven classes of neurotransmitters

• acetylcholine

• amines

• amino acids

• peptides

• purines

• gases

• lipids

what are catecholamines

• they are neurotransmitters formed from tyrosine (amines class)

• includes norepinephrine, epinephrine, dopmaine

what are cholinergic neurons/receptors

they are neurons that secrete acetylcholine and receptors that bind acetylcholine

location they are found, which division of nervous system they are found in, and what kind of receptors they are - acetylcholine - cholinergic nicotinic receptors

• part of acetylcholine class

• they are chemically (ligand) gated receptors

• found in skeletal muscles

• found in the autonomic division of the peripheral nervous system and in the CNS

location they are found, which division of nervous system they are found in, and what kind of receptors they are - acetylcholine - cholinergic muscarinic receptors

• part of acetylcholine class

• they are G protein linked receptors

• found in cardiac and smooth muscle and exocrine and endocrine glands

• found in the CNS

what are adrenergic neurons/receptors

• neurons that secrete norepinephrine or epinephrine and receptors that bind to norepinephrine or epinephrine are called adrenergic

• adrenergic receptors are divided into alpha and beta

• part of the amines class

location they are found, which division of nervous system they are found in, and what kind of receptors they are - norepinephrine receptors

• part of amines class

• they are G protein linked receptors

• found in cardiac and smooth muscles and exocrine and endocrine glands

• found in the CNS

what are the chemicals of the amino acids class

• glutamate

• aspartate

• gamma-aminobutyric acid (GABA)

what is a glutamate receptor called and how does glutamate act in the body

• main excitatory neurotransmitter in the CNS

• acts also as a neuromodulator

• glutaminergic ionotropic receptor or glutaminergic metabotropic receptor

• 3 kinds

how does aspartate act in the body

• it is an excitatory neurotransmitter in the CNS

• part of amino acids class

location they are found, which division of nervous system they are found in, and what kind of receptors they are - gamma-aminobutyric acid (GABA) receptors

• part of amino acids class

• GABA receptor

• chemically (ligand) gated receptor

• found in the CNS

• it is an inhibitory neurotransmitter

location they are found, which division of nervous system they are found in, and what kind of receptors they are - dopamine receptors

• part of the amines class

• called dopamine receptors

• G protein linked receptors

• found in the CNS

location they are found, which division of nervous system they are found in, and what kind of receptors they are - serotonin receptors

• part of the amines class

• called serotonergic receptors

• they are chemically (ligand) gated receptors and G protein linked receptors

• found in the CNS

location they are found, which division of nervous system they are found in, and what kind of receptors they are - histamine receptors

• part of the amines class

• called histamine receptors

• G protein linked receptors

• found in the CNS

location they are found, which division of nervous system they are found in, and what kind of receptors they are - glutamate - glutaminergic ionotropic receptors

• part of amino acids class

• either AMPA or NMDA

• both are chemically (ligand) gated receptors

• both are found in the CNS

location they are found, which division of nervous system they are found in, and what kind of receptors they are - glutamate - glutaminergic metabotropic receptors

• part of amino acids class

• G protein linked receptor

• found in the CNS

location they are found, which division of nervous system they are found in, and what kind of receptors they are - glycine receptors

• part of amino acids class

• called glycine receptors

• chemically (ligand) gated receptors

• found in the CNS

location they are found, which division of nervous system they are found in, and what kind of receptors they are - adenosine receptors

• part of purines class

• adenosine is the chemical

• called purine receptor

• G protein linked receptor

• found in the CNS

location they are found, which division of nervous system they are found in, and what kind of receptors they are - nitric oxide receptors

• part of gases class

• no specific receptor

• doesn’t have a type of receptor or location

how does the neurotransmitter receptor sometimes determine the response of the target tissue in some autonomic pathways

• most blood vessels contain one type of adrenergic receptor (alpha) that causes smooth muscle contraction (vasoconstriction)

• some vessels contain a different type of adrenergic receptor (beta) that causes smooth muscle relaxation (vasodilation)

• both receptors are activated by catecholamines

• in this case, the receptor rather than the chemical signal determines the response

what is a neuroeffector junction

synapse between a postganglionic autonomic neuron and its target cell

what are target tissues of a neuroeffector junction

• smooth muscle

• cardiac muscle

• exocrine and endocrine glands

• CNS

what are varicosities

• they are a string of swollen areas at the distal end of autonomic axons

• they lie across the surface of the target tissue and contain vesicles filled with neurotransmitters

• underlying membrane does not contain neurotransmitter receptors

where are neurotransmitters released

• they are released into the interstitial fluid to diffuse to wherever the receptors are

• receptors are often quite a distance from the site of release

what can release of an autonomic neurotransmitter from a single postganglionic neuron affect

it can affect a large area of target tissue

where does neurotransmitter synthesis occur and how are they stored

• synthesis occurs in the axon varicosities

• neurotransmitters are then packaged into synaptic vesicles for storage

what are the typical autonomic neurotransmitters and what are they synthesized by

typical autonomic neurotransmitters are acetylcholine and norepinephrine which are both synthesized by cytoplasmic enzymes

steps in neurotransmitter release for norepinephrine

1. action potential arrives at the varicosity

2. depolarization opens voltage-gated Ca2+ channels

3. Ca2+ entry triggers exocytosis of synaptic vesicles

4. NE binds to adrenergic receptor on target

5. receptor activation ceases when NE diffuses away from the synapse

6. NE is transported back into the axon

7. NE can be taken back into synaptic vesicles for re-release

8. NE is metabolized by monoamine oxidase (MAO)

release of neurotransmitters - what triggers the release of calcium

voltage-gated calcium channels open when an action potential arrives at a varicosity

release of neurotransmitters - what does calcium do after calcium channels open

calcium enters the neuron and bonds with regulatory proteins

release of neurotransmitters - what is triggered when calcium bonds with regulatory proteins

neurotransmitter vesicles moves to the perimeter of the cell and empty their contents into the synaptic cleft via exocytosis

release of neurotransmitters - what do neurotransmitters do after exocytosis releases them into the synaptic cleft

neurotransmitters diffuse through the interstitial fluid until they encounter a receptor on an effector cell or drift away from the synapse

what effect does the concentration of neurotransmitter in the synaptic cleft have on its target tissue

the more neurotransmitter that is present, the longer or stronger the response is

what influences the concentration of neurotransmitter in a synapse

concentration of neurotransmitter in a synapse is influenced by its rate of breakdown (termination) or removal

release of neurotransmitters - what causes target tissue receptor activation to end

target tissue receptor activation ends when norepinephrine (neurotransmitter) diffuses away from the synapse

release of neurotransmitters - what can happen to neurotransmitters after they diffuse away from the synapse

• norepinephrine (neurotransmitters) can be transported back into the varicosity and moved into synaptic vesicles for re-release

• norepinephrine is metabolized by monoamine oxidase (MAO)

what is each adrenal made of

each adrenal gland is two glands of different embryological origin fused during development

outer portion of an adrenal gland - what’s it called

the outer portion is called the adrenal cortex and is a true endocrine gland

outer portion of an adrenal gland - what does it do

it secretes steroid hormones - aldosterone, cortisol. and androgens

inner portion of an adrenal gland - what is it called

the inner portion is called the adrenal medulla and is a neurosecretory structure