Physiology Exam 2

What is the autonomic nervous system composed of?

sympathetic nervous system (fight or flight) and parasympathetic nervous system (control your body while times of rest)

What does the autonomic system innervate?

Visceral organs (smooth muscles those internal organs such as the intestines), glands, and blood vessels

The ANS has afferent and efferent pathways. The efferent fibers stem from where end end up where?

Have their cell bodies in the spinal cord, and they reach the sympathetic ganglia (collection of neuronal bodies found in the voluntary and autonomic branches of the PNS) on both sides of the vertebral column (is what encloses the spinal cord)

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\-The parasympathetic efferent reach their ganglia at or near the organs.

What is the function of the autonomic nervous system?

Functions as most part at the subconscious level (so involuntary functions in the body b/c this level is concerning with the mind not being fully aware of an action)

What is the function of sympathetic system of the ANS

prepares and mobilizes (organize) the body in emergency cases. (so this occurs during exercise or fear

Sympathetic stimulation in the ANS leads to

\-Think that you are being stimulated

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\-Increased heart rate

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\-constriction of the arterioles of the skin and intestines. (But in the skeletal muscles the arteries will dilate) . this will cause a raise to your blood pressure (is your arteries are getting smaller that means more there is more blood in the tube and the pressure goes up in the tube)

\-Dilation of the pupils

\-Sphincters close (this is a ring of muscles surrounding and serving to guard or close an opening or tube, such as the anus or opening the stomach)

What is the function of the parasympathetic system in the ANS

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Conserves and stores energy (example of this is during sleep

Parasympathetic stimulation in the ANNS leads to what?

Think about your body being relaxed

\-Decrease in heart rate

\-Pupils constrict (get smaller)

\-increased peristalsis (the involuntary constriction and relaxation of muscles of the intestine or another canal to allow contents like food or poop to move forward)

\-Increased glandular activity (gland)

\-Sphincters open (you have an anal spincter and a pyloric sphincter in your stomach)

\-bladder wall is contracted

Explain the organization of the ANS

1\.) Synapses b/w neurons are made in the autonomic ganglia. Parasympathetic ganglia are located near the effector organs (b/c the PNS goes all the way down to the organs). While the sympathetic ganglia are located in or near the paraventricular chain (PVN in our brain tis the important autonomic control centers in our brain)

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2\.) Preganglionic neurons have their cell bodies in the CNS and synapse in autonomic nervous system.

\-preganglionic neurons of the sympathetic nervous system originate in spinal cord \n segments T1-L3, or the thoracolumbar region.

\-Preganglionic neurons of the parasympathetic nervous system originate in the nuclei of \n cranial nerves and in spinal cord segments S2-S4, or the craniosacral region.

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3\.) Postganglionic neurons of both divisions have their cell bodies in the autonomic ganglia and synapse on effector organs (such as the heart, blood vessels and sweat glands)

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4\.) Adrenal medulla (inner part of the adrenal gland, which is a small organ on the top of each kidney) is a specialized ganglion of the sympathetic nervous system.

\-Preganglionic fibers synapse directly on chromaffin cells in the adrenal medulla

\-The chromaffin cells secrete epinephrine (80%) and norepinephrine (20%) into the circulation

What is pheochromocytoma?

Is a tumor of the adrenal medulla that secretes excess amount of catecholamines and with increased excretion of 3-methoxy-4- \n hydroxymandelic acid (VMA).

The origin of the efferent sympathetic outflow in the ANS starts where?

* Cell bodies lie on the lateral horn of the T1-L2/3 spinal cord (thoraco-lumbar)

What is the origin of the efferent parasympathetic outflow?

CN III, CN VII, CNIX and CN X \n and S1, S2, S3 (pelvic splanchnic nerve) (the cranio-sacral)

What are the receptors of the sympathetic system

Adrenergic receptors (help trigger the fight or flight response) These receptors include 3 subtypes of receptors each having its own receptors

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Alpha receptors: alpha-1 and alpha-2

Beta receptors: Beta-1 and Beta-2

Dopamine Receptors: D1 and D2

What are the receptors in the parasympathetic system?

Cholinergic receptors which include two subtypes

\-Nicotinic receptors

\-Muscarinic Receptors

Adrenergic neurons release what neurotransmitter in the ANS?

norepinephrine as the neurotransmitter

What neurotransmitters do cholinergic neurons release in in the ANS (they can actually do this in the PNS or CNS)

Acetylcholine as the neurotransmitter

Peptidergic neurons in the ANS (specifically in the PNS) release which neurotransmitter?

Peptides such as vasoactive inhibitory peptides and something called substance **P**

Where are the Alpha 1 receptors located?

on the vascular smooth muscle of the skin and splanchnic regions, the gastrointestinal (GI) and bladder sphincters, and the radial muscle of the iris. So they function as producing excitation by contracting, and constricting

Alpha 1 receptors are activated by which neurotransmitter?

\-Norepinephrine, released from adrenergic neurons, present in high enough concentration it will activates these receptors.

\-These receptors are equally sensitive to norepinephrine and epinephrine

What is the mechanism of action of Alpha 1 receptors?

\-G protein alpha stimulator → activates Phospholipase C → causes the formation of 1,4,5-triphosphate (IP3)→ this causes the increase of intracellular Ca2+

Where is alpha 2 receptors located?

\-In the presynaptic nerve terminals, platelets, Fat cells, and the walls of the GI tract. These will thus, produce inhibition through relaxation and dilation.

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What is the mechanism of action of the alpha 2 receptors

\-G protein alpha inhibitor→ causes the inhibition of adenylate cyclase→ causes the decrease of cyclic adenosine monophosphate (CAMP)

Where are the Beta 1 receptors located

In the sinoatrial node (SA), atrioventricular node (AV) , and ventricular muscle of the heart.

\-So this produces excitation (so it will increase heart rate, increased conduction velocity, increased contractility)

What neurotransmitters activate beta 1 receptors?

norepinephrine and epinephrine

\-These receptors are more sensitive than alpha 1 receptors

What is the mechanism of action of Beta 1 receptors?

activation G protein alpha stimulator→ leads to activation of adenylate cyclase → leads to increase in cAMP

Where a Beta 2 receptors located?

On vascular smooth muscle of skeletal muscle, bronchial smooth muscle, and in the walls of the GI tract and bladder.

\-This thus, produces relaxation examples of this is dilation of vascular smooth muscle, dilation of bronchioles, and relaxation of bladder wall

What neurotransmitter will activate beta 2 receptors?

They are more sensitive to activation with epinephrine than norepinephrine.

\-So they are more sensitive to epinephrine than alpha 1 receptors.

What is the mechanism of action of beta 2 receptors?

Same as beta 1 receptors

activation G protein alpha stimulator→ leads to activation of adenylate cyclase → leads to increase in cAMP

Where are nicotinic receptors located?

In the autonomic ganglia of the sympathetic and parasympathetic nervous systems, at the neuromuscular junction , and the adrenal medulla.

\-The produce excitation

What neurotransmitters activate them?

Ach and Nicotine.

What blocks nicotinic receptors?

ganglionic blockers in the autonomic ganglia, but not at the neuromuscular junction

What is the mechanism of action of nicotinic receptors?

Ach binds to alpha subunits of the nicotinic Ach receptor→ the nicotinic Ach receptors are also ion channels for Na+ and K+

Muscarinic Receptors are located where?

In the heart, smooth muscle, and glands

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\-They are inhibitory in the heart, so they decrease heart rate, decreased conduction velocity in the AV node.

\-They are excitatory in smooth muscle and glands, so they increase GI motility, increases secretion.

What neurotransmitters activate muscarinic receptors and what blocks they receptors

\-Activated: By Ach and muscarine

\-Blocked: by atropine

What is the mechanism of action of the muscarinic receptors

In the SA node of the heart there is an inhibition of adenylate cyclase → this leads to the opening of K+ channels, slowing of the rate of spontaneous phase 4 depolarization→ decreased heart rate

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\-In the smooth muscle and glands there is a formation of IP3 and increase in intracellular Ca2+

Hypothalamus

\-this is the temperature of the regulation center

\-Thirst and food regulation centers

Midbrain

Micturition center (urinations control center)

Pons

Pneumotaxic center

(regulation of the respiratory rate.

Medulla

\-Vasomotor center (constriction or dilation of blood vessels)

\-Respiratory center

\-Swallowing, coughing, and vomiting center

Neurotransmitters in the preganglionic ANS

Ach

Neurotransmitters in the postganglionic Parasympathetic and sympathetic ANS

Parasympathetic: Ach \n Sympathatic: \n Norepinephrine (NA)

α-1: (postsynaptic) location and action

Located on Vascular smooth muscle contraction \n Pupillary smooth M & pilomotor smooth M

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Action

contraction in mydriasis (dilation of pupils) and erects hair.

α-2: (mostly presynaptic)

Location:

On Adrenergic and cholinergic nerve terminals

Fat cells

platelets

Some Smooth Muscle (presynaptic inhibition and parasympathetic)

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Action:

Inhibits transmitter release

\-Inhibits lipolysis (breakdown of fats)

\-Stimulates aggregation (formation of large clusters of biomolecules)

\-contraction

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B1 recetpors location and action

\-Location is the heart

\-Action stimulates rate and force

B-2 receptors

\-In vascular, bronchial (smooth m) , GI tract, liver pancreatic B cells

Action: Stimulates glycogenolysis (biochemical pathway in which glycogen breaks down into glucose-1-phosphate and glucose.)

and stimulates insulin release

Muscarinic:

in Glands +ve effect, heart –ve effect, \n smooth muscle (except vascular smooth muscle) +ve effect like peristalsis \n Mechanism of action: increased intracellular calcium

Nicotinic

At the neuromuscular junction \n Produce excitation (opening of Na-K channels, depolarization)

Pupil

α2-receptor: Dilatation

Para: Constriction

Ciliary Muscle

Sym: B-rec accommodation

Para Constriction

Lacrimal Gland

Sym: Decreased Secretion

Para: Increased secreation

Submandibular

Sym: α-receptor: Activates viscous

Para: activates secretion of watery \n secretion saliva \n

Parotid

Sym: Vasoconstrictor

Para: Activates secretion of watery saliva

Sublingual

Sym: Decreased secretion

Para: Increased secretion

Coronary Arties of the heart

Sym: β1-rec: +ve Chronotropic, β1-rec: +ve Dromotropic, vasodilatation

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Para: -ve Chronotropic, -ve Dromotropic, vasoconstriction

Bronchi (muscle)

Sym: β2-receptor: Dilatation

para: Constrictor

Vessels of the lung

Sym: Constrictor

Para: Dilation

Glands of the lung

Sym: Decreases constriction

Para: Increases secretion

Gi Tract: Peristalsis (tonus)

sym: β2-receptor: Relaxation

Para: Activation

Gi tract sphincters

Sym: α1-receptor: Constriction

Para: Relaxation

Glands of the GI tract

Sym: Decrease secretion

Para: Increase secretion

Liver

Sym: β-rec: Gluconeogenesis (organisms produce sugars)

para: Glycogenesis (the formation of glycogen from sugar)

Insulin of the pancreas

Sym:

alpha receptor: inhibits its secretion

Bets receptor: Activities its secretion

Exocrine of the pancreas

alpha receptor: Inhibits secretion

Para: Activates secretion

Adrenal medulla

Sympathetic \n \n \n Activates secretion \n

Urinary Bladder Sphincter Muscle

Sphincter Muscle

Sym: Alpha- receptor contraction

para: relaxation

Detrusor M in the urinary bladder

Sym: Beta-receptor: relaxation

Para: Contraction

Uterus of a pregnant female

sym : alpa 1 receptor: contraction

Uterus of a non-pregnant

sym: B2 relaxation

Genitals

Sym: Ejaculation (emission)

Para: Erection (vasodilation)

What are sensory systems?

\-are specialized epithelial cells or neurons that transduce environmental signals into neuronal signals. The environmental signals that can be detected include mechanical force, light, sounds, chemicals, and temp

What are 4 types of sensory transducers

Mechanoreceptors

Photoreceptors

chemoreceptors

Extreme of temp and pain

Mechanoreceptors

respond to mechanical stimulus \n -Pacinian corpuscles \n -joint receptors \n -Stretch receptors in muscle \n -Hair cells in auditory and vestibular systems \n -Baroreceptors in carotid sinus

Photoreceptors

Rods and cones of the retina \n

Chemoreceptors

\-Olfactory receptors \n -Taste receptors \n -Osmoreceptors \n -Carotid body O2 receptors

Extremes of temperature and pain

nociceptors

What are 5 types of fiber types and conduction velocity

A-alpha

A-beta

A-gamma

A-delta

B

C

Fiber types and conduction velocity \n -A-alpha

large alpha-motoneurons \n Conduction velocity: fastest

Fiber types and conduction velocity \n -A-beta

Touch, pressure \n Conduction velocity: Medium

Fiber types and conduction velocity \n -A-gamma

gamma-motoneurons to muscle spindles (intrafusal fibers) \n Conduction velocity: Medium

Fiber types and conduction velocity \n -A-delta

Touch, pressure, temperature, and pain \n Conduction velocity: Medium

Fiber types and conduction velocity \n -B

preganglionic autonomic fibers \n Conduction velocity: Medium

Fiber types and conduction velocity \n -C

Slow pain, postganglionic autonomic fibers \n Conduction velocity: Slowest

What is the receptive field

is an area of the body that, when stimulated, changes the firing rate of a sensory \n neuron. If the firing rate of the sensory neuron is increased, the receptive field is \n excitatory. If the firing rate of the sensory neuron is \*decreased, the receptive field is \n inhibitory.

Steps in sensory transduction

a. Stimulus arrives at the sensory receptor.( ex: photon of light on the retina, a molecule of \n NaCl on the tongue).

\n B. Ion channels are opened in the sensory receptor, allowing current to flow. \n Usually the current is inward, which is depolarization of the receptor. \n C. The change in membrane potential produced by the stimulus is the receptor \n potential, or generator potential.

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Slow adaptation (tonic) of sensory receptors

receptors (muscle spindle, pressure, slow pain) \n -respond repetitively to a prolonged stimulus.

Rapid adaptation (phasic) of sensory receptors

receptors (pacinian corpucle, light touch) \n -show a decline in action potential frequency with time in response to a constant \n stimulus.

Sensory pathways from the \n sensory receptor to the \n cerebral cortex \n A. Sensory receptors

are activated by environmental \n stilmuli. \n -may be specialized epithelial cells \n (taste receptors, auditory hair cell). \n -may be primary afferent neurons \n (olfactory chemoreceptors). \n -transduce the stimulus into \n electrical energy ( receptor \n potential).

Sensory pathways from the \n sensory receptor to the \n cerebral cortex

First order neurons

are the primary afferent neurons \n that receive the transduced signal \n and send the information to the \n CNS. Cell bodies of the primary \n afferent neurons are in dorsal root \n or spinal cord ganglia.

Sensory pathways from the sensory \n receptor to the cerebral cortex \n (Continued) \n C. Second-order neurons

\-are located in the spinal cord or brain stem. \n -receive information from one or more \n primary afferent neurons in relay nuclei and \n transmit it to the thalamus. \n -Axons of second-order neurons usually \n cross the midline in a relay nucleus in the \n spinal cord before they ascend to the \n thalamus. Therefore, sensory information \n originating on one side of the body ascends \n to the contralateral thalamus.

Sensory pathways from the sensory \n receptor to the cerebral cortex \n Third order neurons

\-are located in the relay nuclei of the \n thalamus. From there, encoded sensory \n information ascends to the cerebral cortex.

Sensory pathways from the sensory \n receptor to the cerebral cortex \n (Continued)

Fourth order neurons

\-are located in the appropriate sensory area \n of the cerebral cortex. \n The information received results in a \n conscious perception of the stimulus.

Somatosensory system

The somatosensory system processes information about touch, pain and \n temperature.

Somatosensory pathways

1. Dorsal column system
2. Anterolateral system

Type of somatosensory receptors

1. Mechanoreceptors (for touch)
2. Thermoreceptors (temperature)
3. nociceptors (pain)

Pathways in the somatosensory system \n Dorsal column system

\-processes sensations of fine touch, pressure, two-point discrimination, \n vibration. \n Course: primary afferent neurons have cell bodies in the dorsal root. Their \n axons ascend ipsilaterally to the nucleus gracilis and nucleus cuneatus of \n the medulla. \n From the medulla the second-order neurons cross the midline and ascend \n to the contralateral thalamus, where they synapse on third-order neurons. \n Third-order neurons ascend to the somatosensory cortex, where they \n synapse on fourth-order neurons.

Pathways in the somatosensory system \n Anterolateral system

processes sensations of temperature, pain, and light touch. \n -consists primarily of group of fibers, which enter the spinal cord and \n terminate in the dorsal horn. \n -second-order neurons cross the midline to the anterolateral quadrant of \n the spinal cord and second to the contralateral thalamus, where they \n synapse on third-order neurons. \n -Third-order neurons ascend to the somatosensory cortex, where they \n synapse on fourth-order neurons.

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Thalamus

\-Information from different parts of the body is arranged somatotopically. \n \* Destruction of the thalamic nuclei results in loss of sensation on the contralateral \n side of the body.

Pain

\-is associated with the detection and perception of noxious stimuli (nociception). \n -The receptors for pain are free nerve endings in the skin, muscle, and viscera. \n -Neurotransmitters for nociceptors include substance P. Inhibition of the release of \n substance P is the basis of pain relief by opioids.

What are the fibers for Fast pain

carried by group A-delta fibers. It has a rapid onset and offset, and is \n localized.

Fibers for slow pain

is carried by C fibers. It is characterized as aching, burning, or throbbing \n that is poorly localized.