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Flashcards in ANS Deck (19):
1

Review the definition of the ANS and compare it to the rest of the nervous system.

ANS - portion of the nervous system that is motor to smooth muscle, cardiac muscle, and glands

- functional entity rather than anatomic one and includes parts of CNS and PNS

2

Explain the functional value of the "two neuron chain."

1. Preganglionic Neurons can synapse with multiple Postganglionic fibers creating a "multiplication" effect.
- rapid spread with little imput
- ANS can operate at a subconscious level

2. Exitation Inhibition
- postganglionic neurons must be stimulated to a certain level by excitatory preganglionic impulses before they will fire an impulse (we get close to threshold)
- neuron can get close to firing

3

State the ANS (involuntary) effectors and state their locations.

1. Smooth Muscle Tissue - found in walls of visceral body organs, walls of blood vessels, base of hair follicles, and iris and ciliary body of eye

2. Cardiac Muscle Tissue - found in heart and aorta and pulmonary trunk

3. Glandular Epithelium - found in exocrine and endocrine glands

4

Differentiate the two divisions of the ANS using anatomic, functional, and pharmacologic criteria.

Anatomic Differences

(locations of pre/post ganglionic neurons and distribution of effectors)

Location of preganglionic neuron cell bodies:

-Sympathetic: T1 - L2 segments of spinal cord (lateral gray column)

-Parasympathetic: Brain and sacral part of spinal cord


Location of postganglionic neuron cell bodies:

-Sympathetic: sympathetic trunk ganglia, prevertebral ganglia, terminal ganglia

-Parasympathetic: Autonomic ganglia of CN 3,7,9,10 and terminal ganglia


Distribution of effectors:

-Sympathetic: throughout body

-Parasympathetic: head, neck, thorax, and abdomen (no limbs)

5

Differentiate the two divisions of the ANS using anatomic, functional, and pharmacologic criteria.

Pharmacologic Differences

(neurotransmitters)

Neurotransmitter secreted by preganglionic neurons:

Sympathetic: Acetylcholine (Ach)
Parasympathetic: Acetylcholine (Ach)

Neurotransmitter secreted by post ganglionic neurons:

Sympathetic: Norepinephrine (NE)
Parasympathetic: Acetylcholine (Ach)

6

Differentiate the two divisions of the ANS using anatomic, functional, and pharmacologic criteria.

Functional Differences

(changes in body induced by effector organs)

Changes in the body induces by effector organs:

Sympathetic: fight/flight
Parasympathetic: Homeostasis

7

List some effectors that are stimulated only by the sympathetic part of the ANS.

- sweat glands
- smooth muscle in most vessel walls
- pupillary dilator muscle
- arrector pili muscles at the base of hair follicles
- adrenal medulla

8

List some effectors that are stimulated only by the parasympathetic part of the ANS.

- ciliary muscle of the eye
- pupillary sphincter muscle

9

Outline the structure of the sympathetic part of the ANS and state the effect of its stimulation on common ANS effectors.

1. Preganglionic Neurons in lateral gray horns of spinal cord segments T1-L2

2. Ganglia Near Spinal Cord - preganglionic fibers release Ach, stimulating postganglionic neurons

3. Target Organs - most postganglionic fibers release NE at synapse with effector

4. Creates a fight or flight response

10

Explain why the sympathetic pathways to peripheral effectors usually involves synapses in the sympathetic trunk ganglia. State where synapses occur in sympathetic pathways to central effectors.

1. ????

2. Synapses in sympathetic pathways to central effectors (cardiac, smooth m.t., and glandular epithelium in visceral organs) don't synapse in the sympathetic trunk ganglion. They continue to other peripheral named ganglia:

- CELIAC
- SUPERIOR MESENTERIC
- INFERIOR MESENTERIC

then they synapse onto their postganglionic neurons which are usually through blood vessels to their various central organs

11

List the cranial nerves that carry parasympathetic preganglionic fibers.

CN 3,7,9,10

1. Oculomotor n.
2. Facial n.
3. Glossopharyngeal n.
4. Vagus n.

12

Outline the structures of the parasympathetic part of the ANS and state the effect of its stimulation on common ANS effectors.

Oculomotor N.

1. Oculomotor N.
- ciliary ganglion
effectors: ciliary muscle, pupillary sphincter muscle
= constriction of pupil and change in thickness of lens

13

Outline the structures of the parasympathetic part of the ANS and state the effect of its stimulation on common ANS effectors.

Facial N.

1. Facial N.
- pterygopalatine and submandibular ganglia

effectors: nasal glands, lacrimal glands, salivary glands

= salivation, lacrimation, and secretion

14

Outline the structures of the parasympathetic part of the ANS and state the effect of its stimulation on common ANS effectors.

Glossopharyngeal N.

1. Glossopharyngeal N.
- otic ganglion

effectors: parotid gland

= salivation

15

Outline the structures of the parasympathetic part of the ANS and state the effect of its stimulation on common ANS effectors.

Vagus N.

1. Vagus N.

- terminal ganglia

effectors: visceral organs within neck, thoracic cavity, and abdominal cavity

= decrease heart rate, stimulate peristalsis in alimentary canal and ureters, cause bronchoconstriction, and stimulate secretion by glands

16

Outline the structures of the parasympathetic part of the ANS and state the effect of its stimulation on common ANS effectors.

Pelvic Nerves (in sacral part of spinal cord)

Pelvic Nerves
- Terminal Ganglia

effectors: visceral organs in inferior portion of abdominal cavity

= contraction in wall of urinary bladder, peristaltic waves and various sexual responses

17

Outline the structures of the parasympathetic part of the ANS and state the effect of its stimulation on common ANS effectors.

LOOK AT CHART ON P. 390

18

Name the higher centers which control ANS output.

Medulla Oblongata
- motor output to:
. cardiovascular system
. respiratory system
. digestive system
. urinary system
. reproductive system

Hypothalamus

Fornix

Limbic System (group of nuclei and fiber tracts around the brainstem that includes hypothalamus, fornix, and several other structures)

19

Define sympathomimetic and parasympathomimetic.

Sympathomimetic: drugs that cause a sympathetic fight or flight response (or prevent a parasympathetic response) in the body

ex) eyedrops that cause the eye to dilate, or using an inhaler to dilate the bronchioles

Parasympathomimetic: drugs that cause a parasympathetic reaction/response in the body