A&p Chapter 15 Autonomic Nervous System & Visceral Reflexes

Front 1

What types of processes does the autonomic nervous system (ANS) regulate?

Back 1

*unconscious processes that maintain

homeostasis like BP, body temp, and respiratory airflow

Front 2

What is the ANS?

Back 2

Autonomic Nervous System: a set of motor neuron pathways from the CNS that innervate smooth and cardiac muscle and glands

*sometimes called visceral motor system

Front 3

What types of sensations initiate visceral reflexes?

Back 3

*internal stimuli: stretch, blood, chemicals

*afferent connected to interneurons in CNS

*efferent carry motor signals to effectors

*effectors are glands, smooth and cardiac muscle

Front 4

What are baroreceptors?

Back 4

Arterial stretch receptors

Front 5

What cranial nerve sends signals to the brainstem from the baroreceptors?

Back 5

Afferent neuron in the glossopharyngeal nerve carries the signal to the medulla in the CNS (brainstem)

Front 6

What cranial nerve sends efferent signals to the heart to reduce heart rate?

Back 6

Vagus nerve (efferent) signals travel to the heart and can slow the heart to reduce BP

Front 7

What are the two divisions of the ANS?

Back 7

Sympathetic and parasympathetic

Front 8

What is the basic function of the sympathetic

division?

Back 8

*prepared body physical activity (fight or flight)

*increases heart rate

*BP

*pulmonary air flow

*BG levels

*blood flow to cardiac and skeletal muscle

Front 9

What is the basic function of the

parasympathetic division?

Back 9

Calms many body functions and assists in bodily maintenance (rest and digest), digestion, and was elimination

Front 10

What is meant by autonomic tone?

Back 10

It is the background rate of activity in the ANS. It is the balance between sympathetic and parasympathetic tone.

Front 11

What does the sympathetic tone do?

Back 11

It keeps most blood vessels partially constricted and thus maintains blood pressure. The loss of it can cause a rapid drop in BP--person could go into shock.

Front 12

What does the parasympathetic tone do?

Back 12

Involves the vagus nerves. If they are cut, the heart would beat at its own rate of about 100 beats/min.

Front 13

Where are the sympathetic ganglia located?

Back 13

In the paravertebral chain (prevertebral)

Front 14

What neurotransmitter is used in the sympathetic ganglia? Pre and post?

Back 14

Preganglionic neurons: cholinergic (ACh)

Postganglionic neurons: adrenergic (epinephrine or norepinephrine)

Front 15

What type of receptor is in the sympathetic ganglia?

Back 15

Nicotinic Acetylcholine (ACh)

Front 16

Where do the cell bodies of preganglionic sympathetic axons reside?

Back 16

In the lateral horns of the spinal cord from T1 to L2

Front 17

When sympathetic axons enter the sympathetic chain, where do they go from there?

Back 17

*ascend in the chain and synapse more superior ganglia

*descend in the chain and snaps in more caudal ganglia

*pass through the chain, don't synapse, go to pre-vertebral ganglion

*synapse in the ganglion at the same spinal level from which they arose

Front 18

What is neuronal divergence?

Back 18

It is present in the sympathetic system. Each pre-ganglionic cell branches and synapses on multiple post-ganglionic cells and produces widespread effects on multiple organs.

Front 19

What do cells of the adrenal medulla release when stimulated?

Back 19

Neurotransmitters into the blood called catecholamines (85% epinephrine, 15% norepinephrine, with a trace of dopamine)

Front 20

What are splanchnic nerves?

Back 20

Effectors in the abdominal cavity are innervated by sympathetic fibers in splanchnic nerves. (celiac, superior, and inferior mesenteric ganglion)

Front 21

What are some characteristics of nicotinic receptors?

Back 21

*cholinergic receptors--activated by ACh and nicotine

*located in all autonomic ganglia, adrenal medulla, and at NMJ

Front 22

What is the mechanism of action of nicotinic receptors?

Back 22

ACh binds to alpha subunits of the nicotinic ACh receptor and ion channels for Na and K. They are excitatory when ACh binding occurs. Curare binds selectively to nicotinic receptors

Front 23

What are some characteristics of muscarinic receptors?

Back 23

*located on all heart, smooth muscle, and glands (except vascular smooth)

*inhibitory in the heart--decreases heart rate, conduction velocity (inhibition of adenylate cyclase which opens K channels)

*excitatory in smooth muscle and glands--it increases GI motility and increases secretion (formation of IP3, inositol triphosphate, and increase of Ca2+)

Front 24

What are muscarinic receptors blocked by?

Back 24

atropine

Front 25

What are the five major subclasses of muscarinic receptors?

Back 25

M1, M4, and M5=CNS

M2=heart, inhibitory receptor, acts by reducing cyclic AMP

M3=glands and smooth muscle, excitatory receptor, increases calcium

Front 26

What neurotransmitter stimulates sweat glands?

Back 26

Acetylcholine

Front 27

What is the neurotransmitter most typically used by post-ganglionic sympathetic axons as they stimulate target tissues?

Back 27

In sympathetic: adrenergic (ephinephrine or norepinephrine)

In parasympathetic: cholinergic (ACh)

Front 28

What cranial nerves have parasympathetic axons associated with them?

Back 28

*Vagus nerve (10)

*Facial nerve (7)

*Oculomotor nerve (3)

*Glossopharyngeal nerve (9)

Front 29

Which cranial nerves serve the head?

Back 29

3, 7, and 9

Oculomotor, facial, and glossopharyngeal

Front 30

Which cranial nerves serve the thorax and abdomen?

Back 30

10

Vagus nerve

Front 31

Which autonomic ganglia are in or near the target tissue in the parasympathetic?

Back 31

in or near target organs (long pre-ganglionic, short post-ganglionic fibers)

Front 32

What is the ciliary ganglion cranial nerve associated with and what is its function?

Back 32

This is the oculomotor nerve (3), it sends pre-ganglionic axons to the cilliary ganglion (ACh), post-ganglionic is stimulated by ACh and thus stimulates the pupillary constrictor and the cillary muscle which thickens the lens for near vision

Front 33

What is the otic ganglion cranial nerve associated with and what is its function?

Back 33

This is the glossopharyngeal nerve (9), it sends axons to the otic ganglion (ACh) which sends post-ganglionic axons to the parotid salivary gland

Front 34

What is the pterygopalatine or sphenopalatine cranial nerve associated with and what is its function?

Back 34

It is the facial nerve (7) which sends axons to the pterypalatine ganglion (ACh) which sends post-ganglionic axons to lacrimal glands (tears) and nasal glands (mucus)

It also sends axons to the submandibular ganglion (ACh) which sends post-ganglionic axons to the sublingual and submandibular salivary glands

Front 35

What is the enteric nervous system?

Back 35

It is the nervous system of the digestive tract. Has 100 million neurons in the walls of the tract and has its own reflex arcs that regulate motility of esophagus, stomach, and intestines, and secretion of digestive enzymes and acid

Front 36

What is Hirschsprung disease?

Back 36

Hereditary defect causing absence of enteric nervous system, no innervation in sigmoid colon and rectum, constricts permanently and won't allow passage of feces which impacts above constriction (megacolon is possible or colonic gangrene), perforation of bowel, and peritonitis, and is evident in newborns who fail to have their first bowel movement

Front 37

What is mega colon?

Back 37

A massive dilation of bowel accompanied by abdominal distension and chronic constipation

Front 38

What is colonic gangrene?

Back 38

It is gangrenous bowel. Life threatening condition in which parts of the intestine (bowel) lose their blood supply and die.

Front 39

What is peritonitis?

Back 39

Inflammation of the membrane lining the abdominal wall and covering the abdominal organs

Front 40

What are the 2 enzymes that breakdown norepinephrine?

Back 40

Monamine oxidase (MAO)

Catechol-O-Methyltransferase (COMT)

Front 41

Where are alpha 1 adrenergic receptors found?

Back 41

There are 4 types that all function by second messengers. They are found on vascular smooth muscle of the skin, viscera, GI, bladder sphincters, and radial muscle of iris

Front 42

What is the mechanism of action for the second messengers in alpha 1 adrenergic receptors? What drug is an agonist for these receptors?

Back 42

They produce excitation by contraction or constriction. Inositol triphosphate (IP3) and increase in intracellular Ca2+ concentration. Phenylephrine is an agonic sympathomimetic used as decongestant.

Front 43

Where are alpha 2 adrenergic receptors found?

Back 43

They are found on platelets, fat cells, and walls of GI tract

Front 44

What do alpha 2 adrenergic receptors have for mechanism of action/second messenger? What drug is an agonist/antagonist for these?

Back 44

Produces inhibition by relaxation or dilation. It inhibits adenylate cyclase and decreases cAMP. Clonidine is an agonist and yohimbine is an antagonist.

Front 45

Where are beta 1 adrenergic receptors found?

Back 45

They are found in the SA (sinus) node, AV (atrioventricular) node, and ventricular muscle of the heart

Front 46

What is beta 1 adrenergic receptors mechanism of action? What drug is an antagonist for these?

Back 46

It produces excitation by increasing heart rate, conduction velocity, and increase contractility. It activates adenylate cyclase and production of cAMP. Propranolol is an antagonist (beta blocker).

Front 47

Where are beta 2 adrenergic receptors found?

Back 47

They are found in vascular smooth muscle, skeletal muscles, bronchial smooth muscle, and smooth muscle in GI tract wall, and bladder

Front 48

What are beta 2 adrenergic receptors mechanism of action/second messenger? What drug is an agonist/antagonist?

Back 48

It produces relaxation by dilating vascular smooth muscle, dilation of bronchioles, and relaxation of bladder wall. It activates adenylate cyclase and produces cAMP. Propranolol is an antagonist and albuterol is an agonist.

Front 49

What is the mechanism of action of nicotinic cholinergic receptors?

Back 49

ACh binds to alpha subunits of the nicotinic ACh receptors which are also ion channels for NA and K

Front 50

To what does curare bind?

Back 50

It is selective to nicotinic receptors

Front 51

What is the mechanism by which inhibitory muscarinic receptors function?

Back 51

(in the heart) inhibit adenylate cyclase which leads to the opening of K channels and slows spontaneous depolarization

Front 52

What is the mechanism by which excitatory muscarinic receptors function?

Back 52

(in smooth muscle and glands) formation of inositol triphosphate (IP3) and increase in intracellular calcium

Front 53

Which subclass of muscarinic receptor is most found in the heart?

Back 53

M2--inhibitory receptor acts by reducing cAMP

Front 54

Which subclass of muscarinic receptor is found in the glands and smooth muscle?

Back 54

M3--excitatory receptor acts by increasing Ca2+

Front 55

What is dual innervation?

Back 55

Most viscera receive fibers from both parasympathetic and sympathetic divisions. Both divisions don't normally innervate an organ equally.

Front 56

What are antagonistic effects of dual innervation?

Back 56

They oppose each other. Can be exerted through dual innervation of same effector. Heart rate decreases by parasympathetic and increases by sympathetic. Sympathetic inhibits digestion while parasympathetic stimulates it

Front 57

What are cooperative effects in dual innervation?

Back 57

Seen when 2 divisions act on different effectors to produce a unified effect. Salivation: parasympathetic increases salivary serous cell secretion while sympathetic increases salivary mucous cell secretion

Front 58

What effectors receive only one sympathetic?

Back 58

Adrenal medulla, arrector pilli muscles, sweat glands, some blood vessels

Front 59

Increase in firing frequency causes?

Back 59

Vasoconstriction of blood vessels and increased blood pressure

Front 60

Decrease in firing frequency causes?

Back 60

vasodilation of blood vessels and decreased blood pressure

Front 61

Can sympathetic tone shift blood flow from one organ to another?

Back 61

Yes--its stimulation increases blood to skeletal and cardiac muscles. it can reduce blood to skin in times of emergency, stress, or exercise. It is temporary. Digestion, nutrient absorption, and urine formation can wait, so it constricts arteries in the GI tract and kidneys

Front 62

Function of hypothalamus

Back 62

hunger, thirst, thermoregulation, emotions, and sexuality

Front 63

What happens in the midbrain, pons, and medulla oblongata?

Back 63

cardiac and vasomotor control, salivation, swallowing, sweating, bladder control, and pupillary changes

Front 64

What reflexes does the spinal cord control?

Back 64

Defecation and micturition reflexes. Can be inhibited by the brain consciously.

Front 65

What are sympathomimetics and give a drug example?

Back 65

They enhance sympathetic activity by stimulating receptors or increase norepinephrine release. Phenylephrine--cold remedy--stimulates alpha 1 receptors and dilates bronchioles and constricts nasal blood vessels

Front 66

What are sympatholytics and give a drug example?

Back 66

They suppress sympathetic activity by blocking receptors or inhibiting norepinephrine release. Propranolol is a beta blocker that reduces hypertension by blocking receptors

Front 67

What are parasympathomimetrics and give a drug example?

Back 67

They enhance parasympathetic activity. Pilocarpine relieves glaucoma by contracting iris sphincter (miosis)

Front 68

What are parasympatholytics?

Back 68

They suppress parasympathetic activity. Atropine blocks muscarinic receptors

Front 69

Describe the fight or flight response.

Back 69

*increased arterial pressure, heart rate, contractility, blood flow to skeletal muscle, cellular metabolism, glycolysis, blood glucose, pupil diameter, and lens flattening.

*decreased blood flow to GI tract

Front 70

Describe the rest and digest response.

Back 70

*miosis--pupil constriction

*bronchoconstriction

*lacrimation--tearing

*urination

*erection

*salivation, GI secretions, motility

*defecation